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Critical components for HVDC transmission systems are polymer insulators, which have stricter requirements that are more difficult to achieve compared to those of HVAC insulators. In this study, we investigated the optimal design of HVDC polymer insulators by using a DC electric field analysis and experiments. The physical properties of the polymer specimens were analyzed to develop an optimal HVDC polymer material, and four polymer specimens were prepared for DC breakdown experiments. Single and reverse polarity breakdown tests were conducted to analyze the effect of temperature on the breakdown strength of the polymer. In addition, electric fields were analyzed via simulations, in which a small-scale polymer insulator model was applied to prevent dielectric breakdown due to electric field concentration, with four DC operating conditions taken into consideration. The experimental results show that the electrical breakdown strength and the electric field distribution exhibit significant differences in relation to different DC polarity transition procedures.

Multiple valve unit (MVU), which converts AC to DC and DC to AC, is one of the key elements of high voltage DC (HVDC) transmission. Therefore, the insulation design of MVU against overvoltage should be considered for the stable and reliable operation of HVDC transmission system. Especially, the air clearance of MVU should be calculated based the switching impulse, since it is fatal to MVU in terms of electrical insulation. However, the previous studies were limited to wave front, and the air clearance of the switching impulse is specified only for an ultra-high voltage (UHV) above 750 kV. As a result, it is difficult to calculate the air clearance of MVU which must endure for a switching impulse under 750 kV. In addition, when the switching impulse introduced while the MVU is in normal operation, it is superimposed to DC and creates the most severe situation, but the studies on such subjects are also insufficient. Therefore, as a fundamental step to calculate the air clearance of MVU, the dielectric characteristics of switching impulse and DC superimposed switching impulse in air have been investigated. The experiments on switching impulse showed that the critical flashover voltage was varied according to the curvature of electrode in the gap distance, up to eight times of the electrode radius. However, beyond that gap distance, the critical flashover voltage became similar, regardless of the radius of electrodes. In case of the superimposed experiment, it was performed according to DC pre-stress level and the polarities of switching impulse. The results were most severe when the positive switching impulse was superimposed on the positive DC, and the peak voltage at which flashover occurs was independent of DC pre-stress.

In the design of DC superconducting cables, the electrical insulation design is a critical factor in the cable's performance and reliability. To evaluate the insulation design of DC superconducting cables, DC electric field analysis and experimental verifications should be performed. Wrapped polypropylene laminated paper (PPLP) tape has generally been used to insulate superconducting cable. During the wrapping process, butt gaps are inevitably introduced, and these are filled with liquid nitrogen (LN2) during normal operating conditions. Therefore, the insulation characteristics of the resulting combination of PPLP and liquid insulation should be carefully verified. The objective of this work was to determine the DC electric field transitions when a butt gap is present in a LN2/PPLP composite insulation system. DC electric field distribution and transition were simulated by using COMSOL Multiphysics® software. Also, to verify the characteristics of DC electric field transitions, two kinds of breakdown tests were performed: a ramp voltage breakdown test and a step voltage breakdown test. In both the experimental and analytical works, it was observed that the electric field distributions were totally different while the DC field transition. And, due to the different distributions of electric field, the breakdown characteristics of LN2/PPLP composite insulation systems could be altered.

Background/Aims: To evaluate the efficacy and safety of a controlled release, once-daily formulation of mosapride (UI05MSP015CT) in patients with functional dyspepsia (FD). Methods: Patients with FD were randomly assigned (1:1) to receive either UI05MSP015CT (15 mg once a day, study group) or mosapride (5 mg three times a day, control group) and corresponding placebo for 4 weeks. The primary endpoint was a change in the gastrointestinal symptom score (GIS) evaluated at enrollment and after 4 weeks. Secondary endpoints were changes in the Nepean Dyspepsia Index-Korean version (NDI-K), rate of satisfactory symptom relief, and rate of adverse events. Results: A total of 138 patients were enrolled (female, 73.9%; mean age, 44.0±15.4 years). After excluding patients who violated the study protocol, 59 and 58 patients from the study and control groups, respectively, were included in the per-protocol analysis. No difference was observed in drug compliance between the control and study groups (97.07%±4.52% vs 96.85%±6.05%, p=0.870). Changes in GIS scores were -9.69±6.44 and -10.01±5.92 in the study and control groups. The mean difference in GIS change between groups was 0.33 (95% confidence interval, -1.75 to 2.41), demonstrating non-inferiority of UI- 05MSP015CT (p=0.755). The rate of satisfactory symptom relief was not different between the study and control groups (39.0% vs 56.9%, p=0.053). No differences in change in NDI-K score (14.3 vs 16.9, p=0.263) or rates of adverse events (12.9% vs. 4.4%, p=0.062) were observed between the study and control groups. Conclusions: Once-daily mosapride is not inferior to conventional mosapride in efficacy and is safe in patients with FD. (Gut Liver 2018;12:516-522)

Due to fewer risk of commutation failures, harmonic occurrences and reactive power consumptions, Voltage Source Converter (VSC) based HVDC system is known as the optimum solution of HVDC power system for the future power grid. However, the absence of suitable fault protection devices for HVDC system hinders the efficient VSC-HVDC power grid design. In order to enhance the reliability of the VSC-HVDC power grid against the fault current problems, the application of resistive Superconducting Fault Current Limiters (SFCLs) could be considered. Also, SFCLs could be applied to the VSC-HVDC system with integrated AC Power Systems in order to enhance the transient response and the robustness of the system. In this paper, in order to evaluate the role of SFCLs in VSC-HVDC systems and to determine the suitable position of SFCLs in VSC-HVDC power systems integrated with AC power System, a simulation model based on Korea Jeju-Haenam HVDC power system was designed in Matlab Simulink/SimPowerSystems. This designed model was composed of VSC-HVDC system connected with an AC microgrid. Utilizing the designed VSC-HVDC systems, the feasible locations of resistive SFCLs were evaluated when DC line-to-line, DC line-to-ground and three phase AC faults were occurred. Consequently, it was found that the simulation model was effective to evaluate the positive effects of resistive SFCLs for the effective suppression of fault currents in VSC-HVDC systems as well as in integrated AC Systems. Finally, the optimum locations of SFCLs in VSC-HVDC transmission systems were suggested based on the simulation results.

Adenocarcinoma accounts for most of the malignant tumors which originate from the colon, whereas the adenosquamous carcinoma is rather rare, totaling to about 0.06% of all colon cancers. Herein, we present a case of adenosquamous carcinoma of the transverse colon with hepatic metastasis. The patient is a 72-year-old woman who is presented with a chief of lower abdominal pains. Her colonoscopy has indicated an ulcerofungating mass about 4 cm × 3 cm in size in the distal transverse colon, and the biopsy confirmed her diagnosis of adenosquamous carcinoma. An abdominopelvic computed tomography shows an circumferential enhancing mass on her distal transverse colon with three hepatic metastatic nodules. Transverse colectomy and hepatectomy are later being performed.

High temperature superconducting (HTS) cable has been paid much attention due to its high efficiency and high current transportation capability, and it is also regarded as eco-friendly power cable for the next generation. Especially for DC HTS cable, it has more sustainable and stable properties compared to AC HTS cable due to the absence of AC loss in DC HTS cable. Recently, DC HTS cable has been investigated competitively all over the world, and one of the key components of DC HTS cable to be developed is a cable joint box considering HVDC environment. In order to achieve the optimum insulation design of the joint box, analysis of DC electric field distribution of the joint box is a fundamental process to develop DC HTS cable. Generally, AC electric field distribution depends on relative permittivity of dielectric materials but in case of DC, electrical conductivity of dielectric material is a dominant factor which determines electric field distribution. In this study, in order to evaluate DC electric field characteristics of the joint box for DC HTS cable, polypropylene laminated paper (PPLP) specimen has been prepared and its DC electric field distribution was analyzed based on the measurement of electrical conductivity of PPLP in liquid nitrogen (LN 2 ). Electrical conductivity of PPLP in LN 2 has not been reported yet but it should be measured for DC electric field analysis. The experimental works for measuring electrical conductivity of PPLP in LN 2 were presented in this paper. Based on the experimental works, DC electric field distribution of PPLP specimen was fully analyzed considering the steady state and the transient state of DC. Consequently, it was possible to determine the electric field distribution characteristics considering different DC applying stages including DC switching on, DC switching off and polarity reversal conditions.

—Superconducting equipment has been actively investigated for securing the environment and energy technology (ET) in various parts of the world. Despite these movements, a high voltage cryogenic bushing, which plays an important role of interconnection between the electric power systems and superconducting devices, has not been fully developed due to severe insulation requirements. gas A insulated cryogenic bushing has been investigated as one of our projects since 2010. a basic step to obtain the design As parameters for cryogenic bushing, we focused on the surface flashover characteristics of glass fiber reinforced plastic (FRP) in several insulation gases. the danger of reduction of the dielectric performanceFor the surface flashover tests, several insulation gases including SF6, CF 4 and N 2 gas were prepared. Various length of FRP specimens were fabricated in order to obtain the data for fundamentalcreepage distance of FRP. The first specimen group was from 2 mm to 10 mm with 2 mm intervals and the second specimen group was from 20 mm to 100 mm with 20 mm intervals. And the gas pressure was varied from 1 bar to 4 bar. n AC Aovervoltage test and a lightning impulse test were performed. Then the experimental results of surface flashover were obtained and analyzedBased on these results, it would be . possible to design the optimum creepagedistance of FRP in a cryogenic bushing.

Partial discharge (PD) measurement is one of the effective diagnostic techniques to predict abnormal high voltage dielectric insulation conditions of the electric equipments. PD diagnostic techniques were also could be utilized to evaluate the conditions of cryogenic dielectric insulation media of high temperature superconducting electric equipment in liquid nitrogen. Generally, liquid nitrogen at 77 K is used as cryogenic and dielectric media for high temperature superconducting devices for high voltage electric power systems. But due to generation of bubbles during quench conditions which cause harmful effect on the properties of liquid nitrogen insulation, sub-cooled nitrogen under 77 K was also employed to suppress bubble formation. In this work, investigation of PD characteristics of sub-cooled liquid nitrogen was conducted in order to clarify the relation between PD inception and the temperature of liquid nitrogen. It was observed that measured PDIV (PD inception voltage) shows little differences according to the sub-cooled temperature of liquid nitrogen, but the magnitude and total numbers of PD has been slightly decreased according the decrease of cooled temperature of liquid nitrogen. From experimental results, it was deduced that the sub-cooled liquid nitrogen from 68 K to 77 K, could be applicable without any considerations of the variation of PDIV.

DC fault current limitation in DC distribution network is one of the critical issues which need to be taken care of before they can be practically implemented. High temperature superconductors could be efficiently installed to cope with the problem of DC fault currents. In this paper, a generalized DC high temperature superconducting fault current limiter (SFCL) is modeled by integrating Simulink and SimPowerSystem blocks. This model is designed for limiting DC fault currents in low voltage DC distribution networks. A DC microgrid having a low voltage DC distribution network, an integrated photovoltaic plant and domestic customer load is modeled. Transient analysis of the DC microgrid is performed by generating fault and measuring DC fault currents at critical points. The designed DC SFCL is placed at different strategic locations in DC microgrid and fault current limitation performance of DC SFCL in DC microgrid has been analyzed. Moreover, the affects of rapid impedance changing in the distribution network due to the fault followed by DC SFCL activation is investigated. Finally, the best suitable position and affects of DC SFCL in a DC microgrid along with suggestions for implementation have been proposed.

Superconducting electric equipments have a lot of advantages over the conventional devices such as improvements in overall efficiency, size reduction, high current carrying capability, and also environment-friendly products. Owing to these advantages, many research institutes have been tried to develop commercial superconducting devices, which could be applicable to the high voltage and high current electric networks. But up to now, most of the research works to develop commercial products were delayed because it was not easy to acquire reliable high voltage insulation properties and optimum insulation design skills considering extremely low temperature environments. Furthermore, it was difficult to determine optimum high voltage insulation level due to the lack of high voltage cryogenic dielectric test facilities. Thus, in order to establish the cryogenic dielectric technology regarding insulating design, cryogenic dielectric test skills, and to implement more reliable high voltage superconducting devices, high voltage cryogenic dielectric test facilities should be prepared for extra high voltage superconducting electric equipments. Recently, cryogenic dielectric test facilities were installed including 3 m long 2 m wide cryostat system with bushing, and 1.6 MVA lightening impulse generators, 400 kVA AC overvoltage test system in Korea. In this paper, design and installation of high voltage cryogenic dielectric test system including very big size FRP cryostat and high voltage bushing were minutely introduced. And some test results to develop high voltage bushings for liquid nitrogen cryostat in order to implement extra high voltage level bushings were illustrated. These test facilities will be fully utilized for the optimization of insulation design for extra high voltage superconducting electric equipments.

One of the most important topics regarding the application of superconducting fault current limiters (SFCL) for upcoming smart grid is related to its possible effect on the reduction of abnormal fault current and the suitable location in the micro grids. Due to the grid connection of the micro grids with the current power grids, excessive fault current is a serious problem to be solved for successful implementation of micro grids. However, a shortage of research concerning the location of SFCL in micro grid is felt. In this work, a resistive type SFCL model was implemented by integrating Simulink and SimPowerSystem blocks in Matlab. The designed SFCL model could be easily utilized for determining an impedance level of SFCL according to the fault-current-limitation requirements of various kinds of the smart grid system. In addition, typical smart grid model including generation, transmission and distribution network with dispersed energy resource was modeled to determine the location and the performance of the SFCL. As for a dispersed energy resource, 10 MVA wind farm was considered for the simulation. Three phase faults have been simulated at different locations in smart grid and the effect of the SFCL and its location on the wind farm fault current was evaluated. Consequently, the optimum arrangement of the SFCL location in Smart Grid with renewable resources has been proposed and its remarkable performance has been suggested.

High voltage cryogenic insulation issues need to be addressed in order to promote the commercialization of high temperature superconducting (HTS) equipment. One of the critical components for superconducting devices is the bushing whose role is to safely supply high current to the device. Due to a steep temperature gradient, commercial bushings which have been insulated with SF6 gas could not be directly applied to cryogenic equipment due to liquefaction of SF6 in the cryogenic environment; therefore, alternative suitable structure and insulation methods should be developed. As a fundamental step in the development of the optimum bushings for HTS devices, the breakdown characteristics of liquid nitrogen mixed with liquefied insulating gases such as N2, SF6 and CF4 have been investigated. In particular, we noted the insulation characteristics of CF4 gas whose liquefication temperature is much higher than SF6 gas. Thus, in order to investigate the possibility of substituting CF4 gas for SF6 gas for the bushings of HTS electrical equipment, impulse tests, AC withstanding voltage tests, and partial discharge (PD) tests have been performed. As a result of these tests, it was shown that mixtures of liquefied insulating gases have a much higher breakdown voltage compared to pure liquid nitrogen. Especially in a cryogenic environment, the usage of SF6 gas should be evaluated due to freezing effects. On the other hand, CF4 gas has shown excellent insulation properties even in a cryogenic environment and could be utilized as an insulation gas for high voltage bushings of HTS electrical equipment.

We report a rare case of a gastric plasmacytoma treated with endoscopic resection and oral thalidomide therapy. A 70-year-old man was admitted to our hospital with indigestion. He had no specific medical history and unremarkable laboratory results. Gastroendoscopic findings revealed a focal, erythematous, flat elevated lesion in the anterior wall of the stomach antrum. A biopsy revealed atypical lymphocytes. Endoscopic submucosal dissection (ESD) with an insulation-tipped knife was performed 45 days after diagnosis. Radiological and hematological evaluations, including a bone marrow biopsy, were performed and showed no involvement of other organs. The patient was diagnosed with extramedullary gastric plasmacytoma. Follow-up gastroendoscopy was performed three times during a 2-year period and showed nonspecific ESD scarring. The patient's condition was found to be stable.

Dry-air has been regarded as an attractive insulating medium which could substitute SF6 gas in high voltage electric equipment. Thus, some manufactures announced that they succeeded in developing medium-voltage switchgear only insulated by dry-air. And their final target is to develop extra high voltage level dry-air insulated switchgear. In order to enhance insulation performance of dry-air, it was generally accepted that the control of moisture content in dry-air is critical factor to determine the performance of dry-air But, there are only a few fundamental research works regarding the insulation characteristics affected by the ratio of moisture content in dry-air. In this paper, we'd like to determine the relation between moisture content in dry-air and breakdown characteristics of dry-air. Humidity of dry-air has been successfully controlled by means of water injection in the test chamber. And then AC withstand test and lightning impulse breakdown test were performed using sphere to plane electrode air-gap configurations. From the test results, it was revealed that the AC and impulse breakdown voltage of dry-air was not seriously affected by different humidity condition ranging from 300 PPM to 1,500 PPM humidity in dry-air.

Aortoenteric fistula (AEF) developed after treatment for an abdominal aortic aneurysm (AAA) is a rare but usually fatal complication. We report a rare case of AEF bleeding after endovascular stent grafting for AAA which was managed angiographically. An 81-year-old man presented with hematochezia and acute abdominal pain for 1 day ago. Four years ago, an aortic stent was implanted in the infrarenal aorta for AAA. Endoscopies were performed to evaluate the hematochezia. Evidence of gastrointestinal bleeding was observed, but a clear bleeding point was not detected on upper endoscopy and colonoscopy. Contrast-enhanced computed tomography performed subsequently showed that the bleeding point was located in the fourth portion of the duodenum as an AEF caused by an inflammatory process in the stent-graft. Intra-arterial angiography showed a massive contrast leakage into the bowel via a small fistula from around the aortic stent graft site. Embolization was successfully performed by injecting a mixture of glue and lipiodol into the AEF tract. The patient was discharged with no evidence of gastrointestinal bleeding after the embolization.

Dry-air is recognized as an attractive insulating medium for substituting SF 6 gas in high voltage devices. Recently, Japanese manufacture announced that 72.5 kV has been successfully developed using dry-air as a main insulating medium. However, only a few fundamental research works of dry-air have been reported compared to those of SF 6 . In this paper, two kinds of experiments were conducted to clarify the breakdown characteristics of dry-air. First, the effect of humidity on the breakdown characteristics of dry-air was deeply investigated. And secondly, the effect of electrode roughness on the breakdown voltage of dry-air has been investigated. In order to make artificial specific humidity of dry-air, the experiment chamber has been controlled in vacuum condition under 0.2 Torr and some water was injected before filling the dry-air. Dry-air used for the experiments was composed of about 21% Oxygen and 79% nitrogen and its humidity was controlled of ‒85°C dewpoint temperature. Water could be successfully vaporized in dry-air, and then AC withstand test and lightning impulse breakdown test were performed using sphere to plane electrode airgap configurations. Next, similar breakdown tests were performed considering polished condition, and artificially made surface roughness with 16 μm and 25 μm on the high voltage electrode respectively. From the test results, it was shown that impulse breakdown voltages were slightly decreased with increasing electrode roughness. However, AC withstand voltages did not show any remarkable difference regarding surface roughness, and it was revealed that the breakdown voltage of dry-air was not affected by different humidity condition ranging from 300 PPM to 1,500 PPM humidity in dry-air. AC withstand voltage and negative impulse voltage in this humidity range did not show noticeable difference.

Since the discovery of high-temperature superconductor (HTS), liquid nitrogen(LN 2 ) has not been only utilized as a coolant of superconducting electric equipment but also as an insulation material in cryogenic environment due to its dielectric performance. It also has a lot of advantages over other cryogenic liquid such as less expense and harmless substance, thus it has been widely used in the development of superconducting devices. Up to now, a lot of research works dealing with the breakdown characteristics of LN 2 for distribution-class superconducting devices have been presented worldwide but, few research works about breakdown characteristics of liquid nitrogen in extra high voltage class have been reported due to the limitation of cryogenic test facilities in extra high voltage (EHV) class. In order to study the cryogenic EHV insulation technologies, we have built the cryogenic dielectric test facilities including a fiber reinforced plastic (FRP) big cryostat with cryogenic bushing, a 400 kV AC overvoltage and a 1.6 MV lightning impulse test systems. Using these facilities, we focused on the breakdown characteristics of liquid nitrogen in EHV level which is rather different comparing to the distribution level. With real scale big cryostat, AC overvoltage test and impulse tests have been performed. From the test results, the breakdown characteristics of liquid nitrogen in EHV were suggested. And these test results could be used as basic insulation design data to develop transmission-class superconducting electric equipment.

Conventional protection devices installed for the protection of excessive fault current in the electric power system have a certain response time delay resulting in power system to pass initial peaks of fault current. Superconducting Fault Current Limiter (SFCL) is a novel technology which has negligible power loss and capability to quench initial fault currents instantly and it also could be utilized to cope with excessive fault current problems in upcoming microgrids. This paper presents feasibility analysis results of positioning of the SFCL and its effects on reducing fault current in microgrids. The detailed power system having AC and low voltage DC microgrids consist of integrated wind and photovoltaic farms integrated with a traditional power system is modeled. Transient analyses for the microgrids were performed for the worst case faults with SFCL installed at key locations of the microgrids. It has been observed that SFCL should not be installed directly at the substation or the branch network feeders. This placement of SFCL results in abnormal fault current contribution from the DG sources. The strategic location of SFCL in power grid which limits all fault currents and has no negative effect on the DG sources is found to be in front of the point of integration of the DG sources with the microgrid.

HVDC technology has been widely used for the bulk power transmission due to its advantages over the conventional HVAC such as higher efficiency with larger current carrying capability and lower electrical losses for long-distance transmission. In this regards, many research institutes have put their intensive efforts to commercialize relevant components in order to realize better HVDC transmission system. One of the critical components for HVDC transmission systems is HVDC polymer insulators which shows rather severe requirements compared to HVAC ones. It has been perceived uneasy to achieve relevant insulation properties with proper design of power apparatus under HVDC. Especially, there is few research works presented concerning the insulation properties of insulator which is a fundamental power component in HVDC system. In this work, dielectric insulation characteristics of various silicone composites have been experimentally investigated under DC stress, of which the results could supply essential base for developing HVDC polymer insulator. For this purpose, polymer composite samples have been prepared in different ways by mixing silicone and ATH respectively and then have been under DC stress to evaluate breakdown characteristics. For the comparison both in DC and AC environment, withstand voltage test and surface discharge test under AC were also performed.

AIM: To investigate the correlation between the changes of pancreatic enzyme, the biochemical markers and the clinical results according to the Balthazar computer tomography (CT) grade. METHODS: Between July 2004 and July 2005, we reviewed the charts of 119 patients who were admitted to our hospital with acute pancreatitis. RESULTS: Eighty-three patients (69.7%) were male, and the mean age of the patients was 57 ± 15.7 years. The biliary pancreatitis patients had an older mean age. Forty-nine patients (41.1%) had biliary pancreatitis and forty-six (38.6%) had alcoholic pancreatitis. Group 3 patients had a longer duration of pain (2.51 ± 1.16 vs 3.17 ± 1.30 vs 6.56 ± 6.13, P < 0.001), a longer period of fasting (7.49 ± 4.65 vs 10.65 ± 5.54 vs 21.88 ± 13.81, P < 0.001) and a longer hospital stay (9.17 ± 5.34 vs 14.63 ± 8.65 vs 24.47 ± 15.52, P < 0.001) than the other groups. On the univariate analysis, the factors that affected the radiological grade were the leukocyte count at admission (P = 0.048), the hemoglobin (P = 0.016) and total bilirubin concentrations (P = 0.023), serum lipase (P = 0.009), the APACH II scores at admission (P = 0.017), the APACH II scores after 24 h (P = 0.031), the C-reactive protein (CRP) titer (P = 0.0001) and the follow up CRP titer (P = 0.003). But the CRP level (P = 0.001) and follow up CRP titer (P = 0.004) were only correlated with the radiological grade on multivariate analysis. According to the ROC curve, when we set the CRP cut off value at 83 mg/L, the likelihood ratio for a positive test was 3.84 and the likelihood ratio for a negative test was 0.26 in group 3. CONCLUSION: In conclusion, our study suggests that the CRP with the radiological severity may be used to estimate the severity of acute pancreatitis.

Amiodarone chlorhydrate is a diiodated benzofuran derivative, and it is used to treat cardiac rhythm abnormalities. Hepatotoxicity is a relatively uncommon side effect of amiodarone, and symptomatic hepatic dysfunction occurs in fewer than 1% of the patients taking amiodarone. Cirrhosis is a rare complication that's been confirmed in 12 cases. Peripheral neuropathy occurs in 10% of patients taking aminodarone. We report here on an unusual case of amiodarone-induced hepatotoxicity and peripheral neurotoxicity. A 75 year old man with normal liver function was given amiodarone for treating his atrial fibrillation and heart failure. He developed nausea, vomiting, muscle weakness and wasting after 17.8 months therapy with amiodarone (400 mg orally once per day). Liver biopsy showed the presence of foam cells in the hepatic sinusoids and Mallory bodies in the periportal hepatocytes on light microscopy. Sural nerve biopsy showed demyelination, and nerve conduction studies showed mixed sensorimotor polyneuropathy. These observations show the necessity of monitoring the hepatic function and conducting neurologic examination of the patients treated with amiodarone.

The purpose of this study was to investigate the efficacy and safety of 'docetaxel-5-FU-cisplatin' combination chemotherapy as a first-line treatment in patients with metastatic or recurrent gastric cancer.We investigated a total of 51 patients who were diagnosed as pathologically proven gastric cancer and received 'docetaxel-5-FU-cisplatin' combination chemotherapy between March 2001 and March 2006. All the cases were surgically unresectable because they were either metastatic or recurred gastric cancer. We studied these cases retrospectively on the basis of medical records. The administered doses of decetaxel was 75 mg/m2 and cisplatin 60 mg/m2 on day 1, 5-FU 750 mg/m2 over 24 hrs on day 1 to day 5, every 4 weeks.Among the 51 patients, 21 patients had Eastern Cooperative Oncology Group (ECOG) performance status (PS) 0, 27 patients had PS 1, 3 patients had PS 2. For response rates, 7 (13.7%) achieved complete response, 17 (33.3%) partial response, 12 (23.5%) stable disease, and 15 (29.4%) progressive disease, respectively. The overall response rate was 47.1%. The median time to progression was 6.7 months (2-34 months). Median overall survival was 14.6 months (2.7-62.5 months). Median disease free survival was 9.5 months (4.2-21.9 months). National Cancer Institute-common toxicity criteria (NCI-CTC) grade 4 leukopenia occurred in 10 cases (per 229 cycles). Grade 4 neutropenia occurred in 51 cases, grade 4 thrombocytopenia in 2 cases. Grade 1 mucositis occurred in 32 cases, grade 1 myalgia in 6 cases.'docetaxel-5-FU-cisplatin' combination chemotherapy is an active and tolerable regimen as a first-line treatment in patients with metastatic or recurred gastric cancer.

Due to ac loss in superconducting materials, high cryogenic costs are inevitable when superconducting devices are operated in ac power networks. Thus, dc electric power networks would be regarded as a better choice for the operation of superconducting devices. In order to develop superconducting devices for a dc network, the dc insulation characteristics, which are much different from the ac insulation characteristics, should be clarified. In this paper, in order to investigate the dc insulation characteristics of polypropylene laminated paper (PPLP), which is generally used for dc superconducting cable, a dc breakdown test and a dc electric field analysis were performed. For the dc breakdown test, specimens with three layers of PPLP with one butt gap were fabricated. In order to reveal the breakdown characteristic of PPLP, a dc electric fields calculation in the media at the moment of breakdown was performed considering capacitive and resistive field distributions. Consequently, the capacitive electric field and resistive electric field distributions were determined using dc field analysis techniques and it was found that the butt gap edge is affected enough by the high field strength to cause the breakdown. Furthermore, it was deduced that the butt gap edge acted as a triple-junction point which causes the breakdown.

Conventional high-voltage bushings, which adopt SF6 gas as an insulation media, cannot be directly applied in cryogenic environment due to the liquefaction of SF6 gas. In our previous study, it was shown that SF6 gas could not be used as an insulation gas in cryogenic environment, but instead, CF4 gas has shown excellent insulation properties with little liquefaction phenomena, and have a possibility to be applied for the insulation gas for high-voltage bushings in cryogenic environment. However, in order to apply CF4 gas for cryogenic bushing, it should be determined whether CF4 gas can maintain its insulation characteristics in long-term operation. In order to reveal the long-term insulation properties of various gases, which have a possibility to be applied in high-voltage bushings in cryogenic environment, the long-term breakdown characteristics of CF4 gas, SF6 gas, N2 gas, and dry-air were compared over time in a cryogenic environment. For an experiment, a high-vacuum cryostat and a cryo-cooler were prepared to prevent the evaporation of liquid nitrogen for long-term duration. An fiberglass reinforced plastics bushing was installed on the cryostat to apply high voltage up to 60 kV. A rod to plane electrode was set in a cryostat to determine the breakdown voltage of insulating gases. The lightning impulse and ac overvoltage tests have been performed and the test results were analyzed. From the test, the reduction of breakdown voltage of CF4 gas were observed as time passed by, and it was more severe in SF6 . However, stable breakdown characteristic have been shown with N2 gas. Therefore, increasing the pressure of N2 would be a viable option for increasing the breakdown voltage in a cryogenic environment.

In a smart grid, various kinds of distributed generation (DG) sources could be connected into the main power grid in order to enhance the reliability of the power system. The combination of ac and dc distribution grid are also considered for the efficient connection of renewable power resources. In this case, one of the critical problems due to these integrations is the excessive increase in the fault current because of the presence of DG within the smart grid. In order to protect the smart grid from increasing fault current, a superconducting fault current limiter (SFCL) could be applied, which has negligible power loss and capability to limit initial fault currents effectively. This paper presents feasibility analysis results of the positioning of the SFCL and its effects on reducing fault current in a smart grid having ac and dc microgrid. The detailed power system was implemented with a microgrid having wind farm and low voltage dc grid connected with a photovoltaic farm. Transient analyses were performed for the worst case faults with the different SFCL arrangements. The strategic location of SFCL in the power grid, which could limit fault currents and has no negative effect on the DG sources, was found to be the connection point of integration of the each DG sources in the ac and dc microgrid.

Background/aims Gastric lymphoepithelioma-like carcinoma (LLC) is a rare cancer that presents with a unique histologic pattern that is characterized by poorly differentiated malignant cells infiltrating the background stroma along with massive lymphocyte infiltration. Many studies have shown that gastric LLC is associated with better prognosis than other gastric malignancies. However, the reason for better prognosis has not been clarified and the underlying mechanism remains to be elucidated. Therefore, we attempted to determine the clinical characteristics of gastric LLC and identify its prognostic factors related to improved survival. Methods A total of 18 patients were diagnosed with gastric LLC after resection from 2005 to 2012 at Department of Gastroenterology in Chungnam National University Hospital. The data of these patients were compared with 36 age- and sex-match-ed patients with poorly differentiated gastric adenocarcinoma who also underwent resection during the same study period. Results Postoperative recurrence or metastasis tended to occur less frequent in gastric LLC than in poorly-differentiated gastric adenocarcinoma. Among prognostic factors, only the number of lymph node metastases showed significant difference, with gastric LLC being associated with a smaller number of lymph node metastases. Regarding the disease free and overall survival rate, both were higher for gastric LLC than for poorly-differentiated gastric adenocarcinoma, albeit not statistically significant (p=0.089 and p=0.159, respectively). Conclusions Poorly differentiated gastric adenocarcinoma was associated with a higher number of lymph node metastases at diagnosis than gastric LCC. Other potential factors affecting prognosis were not significantly different between the two cancer types.

Recently, various high temperature superconducting (HTS) power applications have been developed and prepared for field tests and commercial applications. Comparing to conventional power applications, it could offer several advantages such as reduced size and weight, high efficiency, decreased losses, no oil, nonflammable and decrease of CO2 emissions. Besides overload operation is possible with no loss of lifetime. For HTS power applications in low temperature and high voltage environments, partial discharge (PD) measurements in cryogenic dielectric materials of HTS power applications are very important because PD was regarded as primary source for ageing and breakdown of cryogenic materials. One of the diagnostic methods for safety of the power components, the detection of PD taking place inside the apparatus has been widely investigated. The first method, phase resolved partial discharge (PRPD) Analysis was developed in the early 1970s taking the phase information of the applied AC voltage into account. We also proposed a pattern analysis method named chaotic analysis of PD(CAPD) for PDs occurred in liquid nitrogen, considering three normalized parameters obtained from the values between two consecutive PD pulses: amplitude difference (Pt), occurring time difference (Tt) and correlation between Tt and Pt. This pattern analysis method can identify the type of defects by means of PD pattern classification without employing the phase information of the applied voltage signal. For the experimental investigation, three artificial defects have been fabricated considering possible defects formed during the manufacturing process of HTS power applications: turn to turn insulation, floating particle and protrusion. And PD signals originated from these artificial defects are measured and analyzed by means of CAPD. Throughout this work, it seems that the correlation between the consecutive PD pulses, depending on the nature PDs, could be clarified by CAPD.

One of the critical matters yet to be solved for commercial applications of extra high voltage superconducting devices is the optimum design and development of high voltage cryogenic bushings which could withstand both severe insulation requirements and a steep temperature gradient due to the cryogenic environment. Neither conventional extra high voltage bushings insulated by SF6 gas nor composite materials are directly applicable to cryogenic bushings due to an extremely low temperature environment. In order to obtain suitable dielectric performance of bushings in the cryogenic environment, we focused on an alternative insulation gas instead of SF6 such as CF4, which shows excellent dielectric performance under extremely low temperatures, and also on the optimum design of cryogenic bushings, which have a longer creepage distance compared to conventional bushings. In this paper, design factors of cryogenic bushings were discussed, and test results of 60 and 100 kV extra high voltage prototype bushings were discussed in detail. Consequently, it was possible to obtain satisfactory results to verify the insulation level of newly designed extra high voltage cryogenic prototype bushings for superconducting electric power applications.

Due to the existence of AC loss in superconducting materials when an alternating voltage is applied, high cryogenic costs are inevitable to operate superconducting devices in AC networks. Therefore applications of superconducting devices in DC electric power networks could be regarded as the optimum choice for superconducting devices, because superconductors show exactly zero resistance to a DC source. Recently, DC superconducting devices such as DC cables have received noticeable attention as DC power transmission lines. In order to develop DC superconducting devices, the DC insulation characteristics in cryogenic liquids should be clarified. However, up to now, limited research has been reported in this field. In this paper, to clarify the different breakdown characteristics of DC and AC applications, various kinds of cryogenic dielectric sheets including Kraft, Kapton (polyimide) and Nomex (polyamide) papers have been prepared. Furthermore, a penetrating breakdown test for three kinds of sheets and turn-to-turn breakdown tests have been performed in liquid nitrogen (LN2). Consequently, it was found that the prepared sheets have shown 1.7-2.7 times higher dielectric strength than those of AC. Moreover, the Nomex and Kraft sheets have shown a remarkable increase in their dielectric strength in liquid nitrogen compared to air. However, the dielectric strength of the Kapton sheet did not show a remarkable increase in liquid nitrogen. From the turn-to-turn breakdown test, it was proved that the dielectric strength has been linearly increased according to the wrapping number of the sheets and that the DC breakdown voltage was 1.1-2.5 times higher than AC.

High temperature superconducting devices utilize liquid nitrogen (LN2) both for cryogenic liquids and insulating media. Regarding the insulating performance of LN2, it shows excellent characteristics comparable to insulating oil which is widely used for conventional electric equipment. But, detailed complex insulating structure in LN2 composed of cryogenic liquids, solid insulating material and conductor material has not been fully considered yet. In order to commercialize superconducting devices, insulating characteristics of LN2 should be analysed and confirmed to the level of insulating oil. In this work, we focused on the breakdown characteristics of LN2 especially for different electrode materials. Aluminum, Stainless steel, and Copper electrode systems were fabricated and tested in LN2 to verify uniform and non-uniform characteristics of LN2 according to the electrode materials. AC withstand voltage test and lightning impulse test has been performed. From the test results, it was revealed that the breakdown voltages were significantly changed according to the electrode materials. Especially for Stainless steel, it shows prominent enhancement of breakdown voltage compared to copper and aluminum electrode in LN2. Consequently, it was deduced that optimum choice of conductor materials in LN2 is another critical factor to determine complex insulating performance of superconducting devices.

Mantle cell lymphoma has a broad spectrum of endoscopic presentations, such as thick, rigid folds that are indispensible on air insufflation, superficial confluent ulceration, or a polypoidal mass protruding into the lumen. The exact diagnosis is difficult to make because the lesion is in the submucosal layer and inaccessible by biopsy. Lesions will often exfoliate necrotic cells which make interpretation difficult, or they may be too small in number and size and thus indistinguishable from anaplastic carcinoma. We report a case of mantle cell lymphoma with diffuse wall thickening of the whole stomach in a 51-year-old man. The series of endoscopic findings in this case support the role of differential diagnosis of linitis plasica type of advanced gastric cancer with mantle cell lymphoma. (Korean J Helicobacter Up Gastrointest Res 2012;12:42-46)

Department of Internal Medicine, Seoul National University Bundang Hospital, Seongnam, Department of Internal Medicine, Korea University College of Medicine, Seoul, Department of Internal Medicine, Catholic University of Korea College of Medicine, Seoul, Department of Health Promotion Center, Seoul St. Mary's Hospital, Seoul, Department of Internal Medicine, Ewha Womans University School of Medicine, Seoul, Department of Internal Medicine, Soonchunhyang University College of Medicine, Cheonan, Department of Internal Medicine, Hallym University College of Medicine, Seoul, Department of Internal Medicine, Chonnam National University School of Medicine, Gwangju, Department of Internal Medicine, Kyungpook National University School of Medicine, Daegu, Department of Internal Medicine, Chungnam National University School of Medicine, Daejeon, Department of Internal Medicine, Digestive Digestive Research Institute, Wonkwang University College of Medicine, Iksan, Department of Internal Medicine, Inje University College of Medicine, Busan, Department of Internal Medicine, Yonsei University Wonju College of Medicine, Wonju, Department of Internal Medicine, Gachon University Gil Medical Center, Incheon, Chungbuk National University College of Medicine, Cheongju, Department of Internal Medicine, Gangneung Asan Hospital, Gangneung, Cancer Prevention Center, Korean National Cancer Center, Ilsan, Department of Internal Medicine, Kwangju Christian Hospital, Gwangju, Department of Internal Medicine, Eulji University College of Medicine, Daejeon, Department of Internal Medicine, Kyung Hee University College of Medicine, Seoul, Department of Internal Medicine, SMG-SNU Boramae Medical Center, Seoul, Department

Sungkook Kim, Jae Kyu Seong, Geom Seog Seo, Sam-Ryong Jee, Jeong Seop Moon, Mee-Yon Cho, Jae Woo Kim, Moon Gi Chung, Seon Mee Park, Byung Kyu Nah, Su Youn Nam, Kang Seok Seo, Byung Sung Ko, Yun-Ju Jo, Jae-Young Jang, Byeong Gwan Kim, Ji Won Kim, Kyung Sik Park, Hyun-Shin Park, Young Sun Kim, Seon Hee Lim, Chung Hyeon Kim, Min Jung Park, Jeong Yoon Yim, Kyung Ran Cho, Donghee Kim, Seun Ja Park, Geun Am Song, Hyun Jin Kim, Sang Wook Kim, Eui Hyeog Im, Kyoung Soo Lee, Dong Hyo Hyun, Hyun Young Kim, Sun-Mi Kim, Jeong Eun Shin, Chan-Guk Park, Chang-Hun Yang, Soo-Heon Park, Hyun Chae Jung, In-Sik Chung

Gastroduodenal fistula or double pylorus is a very rare condition. It is a fistulous communication between gastric antrum and duodenal bulb. It can be either congenital or acquired. In most cases it is thought to be a complication of gastric ulcer. We recently experienced a case of gastroduodenal fistula in 70 year-old man presenting as epigastric pain. He was diagnosed with non ST elevation myocardial infarction previously, and was taking aspirin. Gastroduodenal communication was revealed by endoscopy. We report a case of gastroduodenal fistula that developed in man who was taking aspirin, with review of the literature. (Korean J Helicobacter Up Gastrointest Res 2012; 12:195-197)

Anaplastic carcinoma of the pancreas is an extremely rare but aggressive, rapidly progressive tumor. It often presents with invasion of adjacent organs and distant metastases. Most cases are inoperable and confirmed by autopsy. A correct diagnosis of stomach invasion by anaplastic carcinoma of the pancreas is important due to the risk of bleeding, perforation by rapid tumor growth, and a poor prognosis. However, an accurate diagnosis is difficult as a result of the various clinical presentations, symptoms, and radiological findings. We herein report a case of anaplastic carcinoma of the pancreas in a 78-year-old woman who presented with stomach invasion mimicking a gastrointestinal stromal tumor. (Korean J Med 2012;83:226-231)

To investigate how many discrepancies occur in patients before and after endoscopic treatment of referred adenoma and the reason for these results.We retrospectively reviewed data from 554 cases of 534 patients who were referred from primary care centres for adenoma treatment and treated for endoscopic mucosal resection (EMR) or endoscopic submucosal dissection (ESD) at Chungnam National University Hospital, from July 2006 to June 2009. Re-endoscopy was examined in 142 cases and biopsy was performed in 108 cases prior to treatment. Three endoscopists (1, 2 and 3) performed all EMRs or ESDs and three pathologists (1, 2 and 3) diagnosed most of the cases. Transfer notes, medical records and endoscopic pictures of these cases were retrospectively reviewed and analyzed.Adenocarcinoma was 72 (13.0%) cases in total 554 cases after endoscopic treatment of referred adenoma. When the grade of dysplasia was high (55.0%), biopsy number was more than three (22.7%), size was no smaller than 2.0 cm (23.2%), morphologic type was depressed (35.8%) or yamada type IV (100%), and color was red (30.9%) or mixed-or-undetermined (25.0%), it had much more malignancy rate than the others (P0.05). All 18 cases diagnosed as adenocarcinoma in the re-endoscopic forceps biopsy were performed by endoscopist 1. There were different malignancy rates according to the pathologist (P = 0.027).High grade dysplasia is the most important factor for predicting malignancy as a final pathologic diagnosis before treating the referred gastric adenoma. This discrepancy can occur mainly through inappropriately selecting a biopsy site where cancer cells do not exist, but it also depends on the pathologist to some extent.