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Background: Accumulation of cholesterol and depletion of calcium induce hepatic injury through the endoplasmic reticulum (ER) stress response. ER stress regulates the calcium imbalance between the ER and mitochondria. Previously, we reported that phosphatase of regenerating liver-1 (PRL-1)-overexpressing placenta-derived mesenchymal stem cells (PD-MSCsPRL-1) promoted liver regeneration through mitochondrial dynamics in a cirrhotic rat model. However, whether PRL-1 is involved in ER stress-dependent calcium is unclear. So, we demonstrated that PD-MSCsPRL-1 improves hepatic functions by regulating ER stress and calcium channels in a rat model of bile duct ligation (BDL). Methods: Liver cirrhosis was induced in Sprague-Dawley (SD) rats using surgically induced BDL for 10 days. PD-MSCs and PD-MSCsPRL-1 (2x106 cells) were intravenously administered to animals, and their therapeutic effects were analyzed. WB-F344 cells exposed to thapsigargin (TG) were cocultured with PD-MSCs or PD-MSCsPRL-1. Results: ER stress markers (e.g., eIF2α, ATF4, and CHOP) were increased in the non-transplantation group (NTx) compared with the control group. PD-MSCsPRL-1 significantly decreased ER stress markers compared to NTx and induced dynamic changes in calcium channel markers (e.g., SERCA2b, IP3R, MCU, and VDAC1) (*pPRL-1 decreased cytosolic CaM expression and cytosolic and mitochondrial Ca2+ concentrations; however, the ER Ca2+ concentration was increased compared to that in PD-MSCs (*pConclusions: These findings suggest that PD-MSCsPRL-1 improved hepatic functions through calcium changes and attenuated ER stress in a BDL-injured rat model. Therefore, these results provide useful data for the development of next-generation MSC-based stem cell therapy for regenerative medicine in chronic liver disease.

In this work, copper indium gallium selenide (Cu(In,Ga)Se2; CIGS) absorbers were grown on polyimide (PI)/molybdenum substrates by a three-stage co-evaporation process at various temperatures, film formation was systemically studied using various advanced characterization methods such as transmission electron microscopy, micro-Raman spectroscopy, Kelvin probe force microscopy, and atom probe tomography. The CIGS films on PI were found to exhibit considerable physical and electrical variations with respect to the process temperature of three-stage co-evaporation. In particular, when the process temperature reached 400 °C, the CIGS absorber on PI began to exhibit controlled microstructure and intergrain properties. By adjusting the microstructure and intergrain properties of the absorber films by means of the process temperature of three-stage co-evaporation, flexible CIGS solar cells on PI with an efficiency of 16.7% (with anti-refection coating) were achieved.

Antiangiogenic therapies targeting vascular endothelial growth factor (VEGF)-A have been commonly used in clinics to treat cancers over the past decade. However, their clinical efficacy has been limited, with drawbacks including the acquisition of resistance and activation of compensatory pathways resulting from elevated circulating VEGF-B and placental growth factor (PlGF) levels. Thus, we developed a novel VEGF-Trap, KP-VR2, which can neutralize VEGF-A, VEGF-B, and PlGF to mediate these problems. KP-VR2 consists of two consecutive second Ig-like domains (D2s) of VEGF receptor 1 (VEGFR-1) fused to human IgG1 Fc. KP-VR2 showed more potent decoy activity than the current VEGF-Trap against VEGF and PlGF. Most importantly, two consecutive D2s of VEGFR-1 can generate two putative binding sites, resulting in a significant improvement in binding capacity. These advances resulted in stronger antitumor efficacy in implanted tumor models than aflibercept and bevacizumab. Overall, the results of this study highlight KP-VR2 as a promising therapeutic candidate for further clinical drug development.

AIM The purpose of the present study was to evaluate and compare clinical outcomes in patients aged >65 years and

As the number of services that use spectrum such as IoT and commercial drones are increasing rapidly every year, it has become very important to efficiently allocate the spectrum resources. Advanced countries are shifting towards open spectrum system which provides the suitable environment for using radio wave and pursue new technological service innovation. Global companies such as Amazon, DHL, and Google are already investing a lot of resources into the commercial drone technology and made significant contributions. Korea’s commercial drone industry, on the other hand, had limited growth because commercial drones are strictly regulated. In this respect, the purpose of this paper is to derive a policy measure for open spectrum to foster the Korean commercial drone industry. The research was conducted as follows: (i) Literature review of open spectrum and commercial drone industry and (ii) Expert interview on key issues. Following implications have been drawn from case studies in other countries and the expert interview: (i) Establishing data-based open spectrum management system, (ii) Designing a plan to develop new service using spectrum in middle and long term, (iii) Selecting spectrum band width exclusive for open spectrum and drone for international compatibility (iv) The need for a unified agency which can manage and regulate drone industry. These results imply that in order to foster the commercial drone industry, it needs a collaboration with the field of spectrum, and an international standard. The contribution of this study is to provide a strategic guideline for the countries that are in the early stage of developing commercial drone industry, and establish policy and legal guidelines to help foster commercial drone industry.

Both the thymus (T) and bone (B) are necessary hematopoietic niches in adult humans. We previously showed that co-transplantation of human fetal T and B tissues into neonatal immunodeficient NOD/SCID IL2Rγ(null) (NSG, N) mice facilitated hematopoiesis. However, transplantation into neonatal mice resulted in high frequency of early death, making it unrealistic for repetitive experiments. In this study, young adult N mice were pre-engrafted with T and B, T alone, B alone or no tissues. The animals were irradiated and injected with autologous fetal liver (FL)-derived CD34(+) cells (34). The resultant mice were TB34N, T34N, B34N and 34N, respectively, and challenged with T cell dependent antigens (Ags). The humanized TB34N mice showed best performance of these mouse models in many aspects resembling the adult human Ag-experienced spleen. The TB34N mice exhibited better hematopoietic reconstitution; balanced development of T- and B-cell, and common progenitor cells; follicular lymphoid structures with a functional germinal center (GC) enriched with follicular dendritic cells (FDCs) and plasma cells (PCs); secretion of hIgG in the sera in response to Ags at comparable levels to those of human; derivations of hIgG mAb-secreting hybridoma clones. Collectively, the humanized TB34N mice could develop an adaptive immunity that was capable of producing Ag-specific hIgG at a significant level via class switching. This unprecedented TB34N platform in humanized mice would be useful in dissecting human immunity, for generating human Abs and clinical applications.

The Jeju-Korea power system is a small-sized network with a system demand ranging from a autumn minimum of 350MW to a summer peak of 716MW. Because Jeju island is well exposed to north-east winds with high speed, applications to connect to Jeju power system are flooded. Considering physical/environmental constraints, Jeju Self-governing Province has also target for the wind power capacity of 1,350MW by 2020. It amounts to two or three times of Jeju average-demand power and wind power limit capacity announced by Korea Power Exchange (KPX) company. Wind farm connection agreements will be signed to maximize utilization of wind resource. In spite of submarine cable HVDC connected to Korea mainland, Jeju power system is independently operated by frequency and reserve control. This study reevaluates wind power limit based on the KPX criteria from 2016 to 2020. First of all wind power generation limit are affected by off-peak demand in Jeju power system. Also the possibility capacity rate of charging wind power output is evaluated by using energy storage system (ESS). As a result, in case of using 110MWh ESS, wind power limit increases 33~55MW(30~50% of ESS), wind power constraint energy decreases from 68,539MWh to 50,301MWh and wind farm capacity factor increases from 25.9 to 26.1% in 2020.

In this paper, the shape accuracy of the stamped hat-type product is quantified and analyzed with ultra high strength steel (UHSS) sheets. The shape of the hat-type product is designed in order to simplify the geometry of the side sill and the stamping methodology is proposed in order to verify the effect of the stamping procedure on the springback amount. Experiments and finite element analyses are conducted with four kinds of the forming sequences. The springback amounts are measured and compared according to the forming procedure with the embossing shape. Experimental result in company with analysis one illustrate that the springback amount is reduced with embossing in the padding operation. They also fully demonstrates the proposed forming procedure and the analysis method can be effectively applied to the process design for producing parts with ultra high strength steel.

In this paper, a frontal crash analysis is carried out with a full vehicle model in order to investigate the influence of stamping effects of auto-body members on the crash characteristics of the vehicle. Stamping effects are considered for load carrying members such as the front side member and the rear lower. From the analysis result considering stamping effects, it is conformed that stamping history has to be considered for longitudinal members simultaneously that transfer the impact load under the frontal impact. Comparison of simulation result with experimental one also shows that the prediction accuracy of the crash analysis is remarkably improved.

Database for the information of the shape accuracy is constructed with the finite element stamping analysis of the center pillar member. Analyses are carried out in order to investigate the effect of tool compensation on the product quality previously performed by an expert in the press shop. The compensation procedure is provided with three sequences for improving shape accuracy of the member by reducing the amount of springback. The analysis result shows that shape inaccuracy in the product is caused by sagging and twisting phenomena from displacement of the section part due to excessive amount of springback. From the database with springback analyses, design modification guidelines are proposed for improving the shape accuracy. The guideline is directly applied to a member with the similar shape and the sound product is obtained successfully reducing the amount of springback.

About supply and demand to see that you need to match, the limitations of wind power capacity is low demand and the commitment of the general generator will exist between the minimum generation. if the turbine`s output can be controlled, The limitation of wind power capacity will be adopted based on instant power generation. Namely, The minimum limits of wind power generation based load operation by calculating the amount that is higher than if the output should be restricted to highest operation. in this paper, we committed to the demand for low enough that the combination of the general generator of wind power capacity to accommodate the operation of determining whether the limit is intended to. For this, power system analysis program PSS/E was used, Jeju system by implementing the model simulations were performed.

The superior shoulder suspensory complex (SSSC) is an extremely important structure composed of a ring of bone and soft tissues at the superior aspect of the shoulder. Double disruption leads to instability of the construct and usually requires operative treatment. Triple disruption of the SSSC is extremely rare and is encountered in high-energy trauma cases often in association with other injuries. The authors experienced a case of triple disruption involving the acromion, coracoid process, and acromioclavicular separation. This type of SSSC disruption is unlikely to have been caused by a single impact and is rather caused by multiple impacts during one traumatic event.

The wind energy is one of the most prospective resources in renewable energy. However, the WTGS shouldn`t be installed indiscriminately because the power system can be negatively influenced by a variable and uncertain nature of the wind energy. It is the reason why it has to be limited to install the WTGS thoughtlessly mentioned above that support the importance of the maximum penetration limit of wind power. It may required that power system operators suggests a new way of power system operation as percentage of the WTGS increase in the existing power system. The wind power is fixed in a limited area, so using rate of the wind power will be increased by installing additional WTGS. In this paper, we have studied on economic evaluation of the wind capacity increased by restricting the output of the WTGS as the way to increase the wind capacity.

Background: Active range of motion deficit is one of the alleged negative influencing factors of rotator cuff repair. Recently, with the popularity of reverse total shoulder arthroplasty (RTSA), there is a tendency toward performing RTSA in cases of nonarthritic large-to-massive tears with pseudoparalysis.Hypothesis: Rotator cuff repair in patients with active motion deficit may yield inferior outcome.Study Design: Cohort study; Level of evidence, 3.Methods: Among 195 complete repairs of large-to-massive rotator cuff tears, 35 patients experienced painful pseudoparalysis preoperatively. Propensity score matching (1-to-1) was performed between pseudoparalytic and nonpseudoparalytic groups. Finally, 29 patients in each group were matched using the following variables: age, gender, dominance, onset period, aggravation period, number of tendons involved, retraction, operation method (arthroscopic or mini-open), rows of repair (single or double), number of anchors, and fatty degeneration of the supraspinatus, infraspinatus, and subscapularis. At least 1 year after surgery (mean, 30.5 months), range of motion, visual analog scale for pain and satisfaction, Constant score, Simple Shoulder Test, American Shoulder and Elbow Surgeons (ASES) score, and University of California, Los Angeles shoulder rating scale (UCLA score) were evaluated. Healing of repaired cuffs was evaluated by computed tomography arthrography.Results: Range of motion was improved in both groups after rotator cuff repair. Active forward elevation had significantly improved postoperatively in the pseudoparalytic group ( P < .001). All functional outcome scores improved at the final follow-up visit compared with preoperative values (all P < .05). Preoperative Constant, ASES, and UCLA scores were significantly inferior in the pseudoparalytic group, but all except the Constant score showed no differences between the 2 groups at the final follow-up ( P = .04). Postoperatively, 7 patients (24.1%) in the pseudoparalytic and 1 (3.4%) in the nonpseudoparalytic group showed pseudoparalysis ( P = .03). Among 37 patients who underwent postoperative computed tomography arthrography, cuff healing was achieved in 6 of 18 (33.3%) in the pseudoparalytic and 9 of 19 (47.4%) in the nonpseudoparalytic group ( P = .385).Conclusion: Recovery from pseudoparalysis after rotator cuff repair was evident in a large portion of the study group, and postoperative function and cuff healing were not different according to the presence of pseudoparalysis. Considering possible complications and longevity of RTSA, rotator cuff repair should be the first-line treatment option for large-to-massive tears.

The power quality of wind energy becomes more and more important in connecting wind-farms to the grid, especially weak grid. This paper presents the simulation of a wind farm of a permanent magnet synchronous generator (PMSG) and a doubly fed induction generator (DFIG). Flicker mitigation is performed by using PMSG as a static synchronous compensator (STATCOM) to regulate the voltage at the point of common coupling (PCC). A benefit of the measure is that integrating two function of to control the active power flow and to reduce the voltage flicker in a wind farm. Simulation results show that controlling PMSG is an effective and economic measure in reducing the flicker during continuous operation of grid connected wind turbines regardless of short circuit capacity ratio, turbulence intensity and grid impedance angle.

： In this paper, using the periodic ground structure (PGS), highly miniaturized branch-line coupler and impedance transformer were realized on Si radio frequency integrated circuit (RFIC). The branch-line couple exhibited good RF performance from 41.75 to 50 GHz, and its size was 0.46x0.55 mm 2 , which is 37 % of conventional one. The impedance transformer exhibited good RF performance from 1 to 40GHz, and its size was 0.01 mm 2 , which is 6.99 % of conventional one. Key words ：Periodic ground structure, RFIC, Branch-line coupler, impedance transformer †교신저자(한국해양대학교 전파공학과, yunyoung @ hhu.ac.kr, Tel:051-410-4426)* 한국해양대학교 전파공학과 1. 서 론 최근 실리콘 반도체 공정기술의 발달에 의해 CMOS의 고주파 성능이 향상됨에 따라, 마이크로파 및 밀리미터파 영역에까지 CMOS의 응용이 가능하게 되었고 [1]-[3] , 이에 따라 고주파용 RFIC (radio frequency integrated circuit) 와 베이스 밴드부의 chip set이 하나의 실리콘 기판상에 집적된 SoC (system on chip)용 단말기의 개발이 가능하게 되었다. 그러나 이러한 실리콘 반도체 기술의 발전에도 불구하고, 아직까지도 결합기 및 분배기, 필터등의 대부분의 RF 수동소자들은 큰 점유면적으로 인해 실리콘 IC 내부에 집적되지 못하고 있으며, 실리콘 IC 외부의 프린트 기판 상에 설계 및 제작되고 있는 실정이다

In this study, using a periodical ground structure(PGS) on GaAs monolithic microwave integrated circuit(MMIC), transmission line with a high isolation characteristic was developed for application to compact signal/bias lines of highly integrated MMIC. And the origin of the high isolation characteristic was theoretically investigated. The high isolation characteristic was originated from a resonance between adjacent microstrip lines employing PGS. With only a spacing of , the coupled microstrip line employing PGS showed an isolation value of -47 dB at 60 GHz. The frequency range for high isolation was easily controlled by changing the PGS structure. Above results indicate that microstrip lines employing PGS are very useful for application to compact signal/bias lines of highly integrated MMIC requiring a high isolation characteristics between lines. In addition, equivalent circuit employing closed-form equation for the coupled line with PGS was also extracted.

Embedded system technology can improve electrical performance and reduce assembly cost compared with those discrete component technologies. In this paper, simulation and characterization of embedded capacitors will be presented. The embedded capacitors were simulated and characterized employing eight layered printed circuit boards. Fabrication process of multilayer embedded capacitors will be presented. Theoretical considerations regarding the embedded capacitors have been paid to understand the frequency dependent impedance behavior. Frequency dependent impedances, capacitances, and quality-factors of fabricated embedded capacitors were investigated. As a result, parasitic inductance was developed mainly through via holes and it has almost same value regardless of different capacitances. Frequency dependent capacitance values of fabricated embedded capacitors were well matched with those of simulated embedded capacitors. Temperature dependent capacitance and loss tangent of fabricated embedded capacitor were presented.

Tool design is carried out for a press forming of a tubular axle in the rear suspension assembly based on the result of the finite element analysis. The analysis incorporates a three-dimensional elasto-plastic finite element method with the explicit time integration scheme by using LS-DYNA3D. The analysis simulates the two-stage stamping process and it fully evaluates the deformation mechanism by forming and springback. With the trial tool shape, simulation is performed in order to investigate failure by wrinkling, shape inaccuracy and the local deformation. This paper identifies such unfavourable mechanism in the tubular press forming and proposes a new tool design with a guideline for modification in the design of the process and sequential tool shapes. The finite element analysis result with the improved tool design confirms that the proposed design not only reduces the possibility of failure, but also improves the quality of a formed product.

In this paper, an optimum design is carried out with finite element analysis to determine process parameters which reduce the amount of springback and improve shape accuracy of a deep drawn product with the channel shape. Without springback simulation usually performed with an implicit solving scheme, the study uses the amount of stress deviation through the sheet thickness direction in the deep drawn product as an indicator of springback. The simulation incorporates the explicit elasto-plastic finite element method for calculation of the final shape and the stress deviation of the final product. The optimization method adopts the response surface methodology in order to seek the optimum condition of process parameters such as the blank holding force and the draw-bead force. The present optimization scheme is applied to the design of the variable blank holding force in the U-draw bending process and the application is further extended to the design of draw-bead force in a front side member formed with advanced high-strength steel (AHSS) sheets made of DP600. Results demonstrate that the optimum design of process parameters decreases the stress deviation throughout the thickness of the sheet and reduces the amount of springback of the channel shaped part. The present analysis provides a guideline in the tool design stage for controlling the evolution of springback based on the finite element simulation of complicated parts.

Objectives The epidermal growth factor receptor (EGFR) abnormalities including amplification, mutation, and overexpression are frequent in non-small cell lung cancer (NSCLC). We investigated in vitro and in vivo antitumor activity of ER2, a novel human anti-EGFR monoclonal antibody, in NSCLC. Methods A panel of NSCLC cell lines (A549, H460, H322, H358, H1299, HCC827, PC9, H1975, and PC9-GR) was used to evaluate in vitro antitumor activity of ER2 and cetuximab. The inhibitory effects of ER2 and cetuximab on downstream signaling were assessed by western blot. Secreted VEGF was measured by Human VEGF Quantikine ELISA kit. Antitumor effects of ER2 and cetuximab as single agents and in combination with cisplatin were evaluated in H322, HCC827 and A549 xenograft models. Results ER2 efficiently inhibits EGFR and its downstream signaling molecules including Akt and Erk1/2 in NSCLC cell lines with wild-type or mutant EGFR. ER2 inhibited cell viability of H322, HCC827 and A549 cells in a dose-dependent manner by inducing cell cycle arrest and apoptosis. Also, ER2 suppressed EGF-stimulated VEGF production as efficiently as cetuximab in H322, HCC827 and A549 cells. Moreover, ER2 alone and in combination with cisplatin showed a significant anti-tumor efficacy in xenograft mouse models. Conclusion Taken together, ER2 has significant anti-tumor activity in in vitro and in vivo NSCLC models, suggesting a rationale for clinical development of ER2 in NSCLC.

Generation of electricity using wind power has received considerable attention worldwide in recent years. In order to investigate the impacts of the integration of wind farm into utilities' network, various studies have been investigated. One such impact is related to the Critical Clearing Time (CCT) of wind power generation system. This paper reports investigation into the factors that influence the transient behavior of the wind power generation system following network fault conditions. It is shown that CCT can be affected by various factors contributed by the network. Such factors include capacity of wind power, power factor, the length of the interfacing line, etc. This investigation is conducted on a simulated grid-connected wind farm using Digsilent Power Factory.

This paper presents the simulation modeling and analysis of variable wind speed turbine system(VWTS) using the doubly fed induction generator(DFIG) connected the back to back converter system in the rotor side. In the simulation, using the model system which has the 660[kW] rated power, blade control and the dual converter system are modeled for verifying the control characteristics. The VWTS is controlled by the optimal pitch angle for maximum output power under the rated wind speed, and for the rated output power over the rated wind speed. And also power factor is controlled by the reactive power. To verify the effectiveness of the proposed method, simulation results are compared with the actual data from the V47 VWTS located in Hangwon wind farm in Jeju-Do. According to the comparison of these results, this method shows excellent performance.

A design sensitivity analysis scheme is proposed for an elasto-plastic finite element analysis with explicit time integration using a direct differentiation method (DDM). The direct differentiation scheme proposed deals with large deformation, an elasto-plastic constitutive relation considering the planar anisotropy, shell elements with reduced integration and complicated contact between the sheet and the dies. The design sensitivities with respect to the process parameter are calculated with direct analytical differentiation of the governing equation. The present DDM result is compared with the result obtained from a finite difference method (FDM) in sheet metal forming processes such as a cylindrical cup drawing process and a U draw-bending process for the verification of its reliability, accuracy and versatility. DDM results show good agreement with FDM results. Results fully demonstrate that sensitivity calculation with FDM is sometimes very dangerous since it could lead to a fatal pitfall and selection of the sensitivity scheme should be carefully done for specific problems. The analysis shows that the sensitivity of state variables provides useful information not only for the strain control but also for the inspection of defect initiation such as fracture or wrinkle. The result demonstrates that the sensitivity calculation scheme proposed is applicable to analysis and design of complicated sheet metal forming.

Process optimization is carried out to determine process parameters which satisfy the given design requirement and constraint conditions in sheet metal forming processes. Sensitivity -based-approach is utilized for the optimum searching of process parameters in sheet metal forming precesses. The scheme incorporates an elasto-plastic finite element method with shell elements . Sensitivities of state variables are calculated from the direct differentiation of the governing equation for the finite element analysis. The algorithm developed is applied to design of the variablc blank holding force in deep drawing processes. Results show that determination of process parameters is well performed to control the major strain for preventing fracture by tearing or to decrease the amount of springback for improving the shape accuracy. Results demonstrate that design of process parameters with the present approach is applicable to real sheet metal forming processes

Design sensitivity analysis scheme is proposed in an elasto -plastic finite element method with explicit time integration using a direct differentiation method. The direct differentiation is concerned with large deformation, the elasto-plastic constitutive relation, shell elements with reduced integration and the contact scheme. The design sensitivities with respect to the process parameter are calculated with the direct analytical differentiation of the governing equation. The sensitivity results obtained from the present theory are compared with that obtained by the finite difference method in a class of sheet metal forming problems such as hemi-spherical stretching and cylindrical cup deep-drawing. The result shows good agreement with the finite difference method and demonstrates that the preposed sensitivity calculation scheme is a pplicable in the complicated sheet metal forming analysis and design.Ā

Optimum tool design is carried out fur a multi-stage rectangular cup deep-drawing and ironing process with the large aspect ratio. Finite element simulation is carried out to investigate deformation mechanisms with the initial design made by an expert. The analysis considers the deep drawing process with ironing for the thickness control in the cup wall. The analysis reveals that the difference of the drawing ratio within the cross section and the irregular contact condition produce non-uniform metal flow to cause wrinkling and severe extension. For remedy, the modification guideline is proposed in the design of the tool and the process. Analysis results confirm that the modified tool design not only improves the quality of a deep-drawn product but also reduces the possibility of failure. The numerical result shows fair coincidence with the experimental one. After tryouts of the tool shape, the rectangular cup has been produced in the transfer press.

Tool design is carried out for a multi-stage deep drawing and ironing process of a rectangular cup with the large aspect ratio using the result of the finite element analysis. The analysis incorporates three-dimensional continuum elements for an elasto-plastic finite element method with the explicit time integration scheme using LS-DYNA3D. The analysis simulates the five-stage deep drawing and ironing process with the thickness control of the cup wall. Simulation is performed in order to investigate the failure by tearing during the forming process at the initial state of tool design. The analysis reveals that the difference of the drawing ratio within the cross section induces non-uniform metal flow which causes severe local extension. The irregular contact condition between the blank and the die also induces non-uniform metal flow which causes local wrinkling. This paper identifies such unfavorable mechanism in the rectangular cup drawing with ironing and proposes a new tool design with the guideline for modification in the design of the process and the sequential tool shape. The finite element analysis result with the improved tool design confirms that the proposed design not only reduces the possibility of failure but also improves the quality of a deep-drawn product. The numerical result shows fair coincidence with the experimental result.

Finite element analysis of multi-stage deep drawing processes is carried out for the process design of rectangular cup drawing with a large aspect ratio. The analysis incorporates shell elements for an elasto-plastic finite element method with an explicit time integration scheme using LS-DYNA3D. Simulation is performed for thorough investigation of failures such as tearing and wrinkling during the forming process. The analysis reveals that the difference of the drawing ratio within the cross-section produces non-uniform metal flow to cause wrinkling and severe extension. The irregular contact condition between the blank and the die also induces non-uniform metal flow. This paper identifies such an unfavorable mechanism in rectangular cup drawing and proposes a modification guideline in the design of the process and the tool shape. The analysis result confirms that the modified design not only improves the quality of a deep-drawn product but also reduces the possibility of failure.

An inverse finite element approach for multi-stage deep-drawing processes is introduced for robust capability to determine the optimum blank shape from the desired final shape and to obtain the thickness strain distribution in the final shape with a small amount of computing time and effort. A direct numerical analysis of multi-stage deep-drawing processes is extremely difficult to carry out because of its complexities and convergence problems as well as tremendous computing time. The analysis of elliptical or rectangular cup drawing with large aspect ratio is likewise very difficult with respect to the design process parameters including the intermediate die profiles. In order to overcome the difficulties, an inverse scheme is proposed in the present analysis and design. The multi-stage inverse analysis deals with the convergence among intermediate shapes and the corresponding sliding constraint surfaces. In this paper, finite element inverse analysis is applied to multi-stage deep-drawing processes in order to calculate the thickness strain distribution in each intermediate shape and to design the intermediate die shapes. The original design has been modified to enhance the discrepancy in the thickness strain distribution for each intermediate shape.

The paper is concerned with evaluation of stress components in elasto-plastic bending for each increment step in finite element analysis using a four-node isoparameteric quadrilateral element. It demonstrates the effect of the integration scheme on the accuracy of a solution with stress evaluation. It is noted that conventional integration schemes cause inaccurate evaluation and oscillatory behaviour of stress components while a reduced integration scheme with hourglass control yields accurate evaluation. As a benchmark problem, elasto-plastic bending is investigated for calculation of the stress and strain. The results fully demonstrate that finite element simulation in the usual way is sometimes very dangerous since it could lead to a fatal pitfall and the selection of the integration scheme should be carefully done for specific problems.

A subcarrier and bit allocation period (SBAP) is proposed based on the mobile speed for OFDM systems. It is assumed that users have different SBAPs according to their mobile speeds. The overhead is considered while transmitting the subcarrier and bit assignment information (SBAI). The optimum SBAP of each user is determined such that the overall throughput including SBAI can be maximized. Simulation results show that the proposed scheme outperforms other schemes. It is also demonstrated that the proposed scheme is insensitive to an error in the estimation of mobile speeds

This paper concerns the optimum condition of finite elements in simulation of elasto-plastic bending. The effect of the integration scheme and the number of finite element layers on calculation of the stress and the strain is thoroughly investigated and some remedies are suggested. As a benchmark problem, an elasto-plastic bending problem is studied for the calculation of the stress and the strain. The calculation directly estimates stress and strain distribution along the thickness direction and shows the oscillatory behavior ol the stress and the incompatible behavior of the strain. The results tully demonstrate that the finite: element simulation in the usual way is sometimes very dangerous since it could lead to a fatal pitfall. This study proposes the optimum condition of finite elements especially in simulation of elasto-plastic bending with a proper integration scheme.

This paper shows how the capacity credit of wind power in Korea-Jeju. As more wind capacity is added in the nation, the question of wind's capacity credit(effective of capacity or capacity value) is raised. This paper introduces methodologies for Korea-Jeju, and it provides seasonal rates of the capacity credit of wind power plant. So, this paper provides a good reference to establish the Korea power supply master plan.

This paper investigates the variations of wind power in Korea-Jeju and discusses the amount of reserve needed to handle unpredicted short-term variations. Construction of wind power plant has been rapidly increased since Korea-Jeju is known as the most suitable for wind power plants in Korea. But implementing wind power generation inevitably introduces new challenges due to its intermittent nature. In the paper, it is introduced the present and prospect of wind plant construction in Jeju. And it provides an indication of the variability of wind power plant and discussed the reserve of conventional power station for wind power fluctuation in Korea-Jeju power system. So, this paper proposes the way of secure operating in Korea-Jeju power network.

This paper presents the power quality analysis of Jeju island power system connected with wind farms during HVDC system overhaul period on the wind power fluctuation. It is for indicating the influence of wind farm operation in steady and transient state in Jeju island power system. For the computer simulation, three kinds of main item are modeled, which are several wind farms, thermal power plants and Jeju power loads. To analyze the influence of the wind power generation to the Jeju power system on the diverse power penetration, two kinds of simulations are carried out by using the PSCAD/EMTDC program. One is the steady state operation when several wind farms in Jeju island are disconnected from the Jeju power grid instantaneously. With the comparison of these results, it is useful for analyzing the power quality of Jeju power system for penetrating the wind farms to the power grid without any harmful effect.

In this paper, the influence of the stamping effect is investigated in the performance analysis of a side structure. The analysis covers the performance evaluation such as crashworthiness and NVH. Stamping analyses are carried out for a center pillar, and then, numerical simulations are carried out in order to identify the stamping effect on the crashworthiness and the natural frequency. The result shows that the analysis considering the forming history leads to a different result from that without considering the stamping effect, which demonstrates that the design of auto-body should be carried out considering the stamping history for accurate assessment of various performances.

A 24 GHz low-noise amplifier (LNA) and mixer for automotive radar applications was designed using a standard 0.13-mum CMOS technology. For mixer, single balanced resistive mixer was employed to suppress LO leakage signal on RF port. At 24 GHz, the mixer showed a conversion loss of -5.5 dB, an LO leakage suppression of -56.2 dBc on RF port, and 3rd input intercept point of 12 dBm. To achieve sufficient gain, this LNA is composed of three cascaded common-source stages. Source degeneration inductor was used to achieve low noise, and gate resistive matching was used to increase stability. The LNA showed a gain of 15.3 dB and a noise figure of 4.49 dB at 24 GHz, and it showed unconditional stability.

This paper presents the modeling and power quality analysis of Jeju island power system connected with wind farm, current source type HVDC system, and thermal power plant. It is for indicating the influence of wind farm operation in steady and transient state in Jeju island power system. For the computer simulation, four kinds of main items are modeled, which are 83 (MW) wind farm, 300 (MW) HVDC system, thermal power plant, and Jeju power load. To analyze the influence of the wind power generation to the Jeju power system, two kinds of simulations are carried out by using the PSCAD/EMTDC program. One is the steady state operation under the different wind speeds, and the other is the transient state operation when all of wind farms in Jeju island are disconnected from the Jeju power grid instantaneously due to the over wind speed than the rated value. These comparative studies are useful to analyze the influence of wind farms on the Jeju island power system stability.

This paper presents the modeling of Jeju island power grid system connected with wind farm, current source type HVDC system, and thermal power plant using PSCAD/EMTDC. It is for analyzing the characteristics of thermal power plant, HVDC system and wind farm operation in steady and transient state. For the computer simulation, four kinds of main items are modeled, which are 83(MW) wind farm, 300(MW) HVDC system, thermal power plant and Jeju power grid load. To analyze the influence of the wind power generation in Jeju power grid system, two kinds of simulations are carried out. One is the steady state operation under the variable wind speed, and the other is the transient state operation when all of wind farms in Jeju island are disconnected from the Jeju power grid instantaneously due to the over rated wind speed. With the simulation results, it is useful to analyze the operating characteristics of power thermal plant, HVDC system, and wind farms on Jeju island power grid system, and the system stabilities.

This paper investigates the impact that arises when integrating wind power in Korea-Jeju power system and discusses the interconnection consideration in future network. Penetration of wind power in the present power system of Jeju island has a little influence on the operation and control of the grid to which the wind parks are connected. The interconnection of wind energy system to the system brings challenges of its own, especially the future network of Jeju island. These challenges include power quality, active and reactive power flow, network stability, service stabilization, etc.