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The deep mesa process for pixel isolation with ICP-RIE (Inductively Coupled Plasma – Reactive Ion Etching) was studied to develop InAs/GaSb type-Ⅱ superlattice (T2SL) LWIR photodetector with nBn structure. To reduce the lateral diffusion current component of the dark current components, it is essential to accomplish a proper deep dry etching process that can completely isolate absorption layer. In this work, ICP-RIE dry etching was studied to implement the smooth, vertical and isolated pixels. By increasing substrate temperature and adjusting the ratio of Ar in BCl3/Ar gas, it was found that the etch rate was largely increased and mesa shpae has become perpendicular and smooth. It was also found that dark current density was increased as the surface roughness increased. For the best sufrgace roughness, the dark current density of 15 μm pitch device fabricated exhibited 4.92x10-6 A/cm2 at and applied bias of -0.1 V and a temperature of 80 K.

High operating temperature(HOT) is the key for low size, weight and power(SWaP) detector development and SWaP detector is the key for modern weapon system such as unmanned aerial vehicle(UAV) and man portable system. The low dark current that determines the operating temperature can be achieved by adopting InAs/InAsSb type-II superlattice(T2SL) absorber and nBn structure. In this work, HOT mid-wavelength infrared(MWIR) detector with InAs/InAsSb T2SL absorber and AlAsSb barrier was developed. The AlAsSb barrier shows excellent lattice match with GaSb substrate. Only the dry etch for pixel reticulation was applied to fabricate the device. At 80 K, dark current density is 2e-9 A/cm2 at the bias -0.2 V and, at 130 K, 2e-7 A/cm2 at the bias -0.1 V. The quantum efficiency was measured for both front side illumination and back side illumination. The back side illumination offers higher quantum efficiency than the front side illumination. The average quantum efficiency is about 50 % for front side illumination with 3 μm absorber. The 640 x 512 VGA format focal plane array(FPA) with 15 μm pitch was fabricated to study the temperature dependency of electro-optical characteristics. It was found that mean noise equivalent temperature difference(NETD) below 150 K is 15 mK, which is limited by the well capacitance. As the temperature increases NETD increases proportional to the dark current.

We report our recent work on the fabrication of type-II superlattice (T2SL) LWIR nBn photodetectors. It is well known that the dangling bonds or the oxidized element on the etched mesa sidewall increase a dark current. Therefore, the passivation and treatment process for the mesa surface is the key for detector performance. In this work, we present an in-situ surface plasma treatment after the dry-etch process for the pixel isolation. To investigate the effects of the plasma treatment for the various gases (CHF3, H2, and H2/Ar), the optical and electrical analysis were performed. The results show that H2/Ar plasma treatment was effective for removing Sb-oxides at dry-etched surface. The fabricated devices which was measured at -0.1 V and 80 K shows the dark current density of -3.9 ｘ 10-6 A/cm-2 .

In this work, the resistance switching characteristics of Al-doped HfO2 thin films were investigated with by systematically varying the Al concentration and analyzing of the microstructure and the chemical bonding states. TiN/Al-doped HfO2/Pt metal-insulator-metal stacks were fabricated with various Al concentrations of up to 16.8% by using reactive DC magnetron co-sputtering. X-ray diffraction and transmission electron microscopy measurement showed that HfO2 doped with more than 10.4% Al had an amorphous structure, while HfO2 doped with Al of less than 5.6% had a crystalline structure. X-ray photoelectron spectroscopy (XPS) showed that the concentration of non-lattice oxygen in Aldoped HfO2 films increased with increasing Al up to 5.6% and was saturated for Al concentrations above 5.6%. TiN/Al-doped HfO2/Pt stacks showed typical bipolar resistance switching characteristics. HfO2 doped with Al = 5.6% showed the smallest grains and the smallest uniformity in the forming electric field and the SET/RESET resistance distribution. We conclude that the grain boundaries play a more important role than point defects such as non-lattice oxygen in the resistance switching.

Computational fluid dynamics (CFD) is nowadays a powerful and reliable tool for simulating different flow processes and temperature. CFD is used to analyze the various pot geometries and operative variables in 55% Al-Zn pot of CGL. In this research, different strip velocities were assumed and then shown the flow pattern in the pot that was similar in the different strip velocities. Temperature distribution in the pot depended on inductors and inlet strip temperature at the steady condition. Generation of dross particles and transport models were considered to describe dross particles evolution inside the pot. In order to observe dross influence by scrap location, dross particles were generated upon the sink roll. Floating time of dross particles is different by scraper locations above the sink roll.

The characteristics of resistive switching of TiN/HfO2/Ti/HfO2/Pt/Ti stacks on SiO2/Si substrates were investigated and compared to TiN/HfO2/Pt/Ti stacks in order to study Ti interlayer effects on resistive switching. The Ti interlayers were deposited in situ during the reactive sputtering of HfO2 films. The current–voltage measurements showed that the Ti interlayers enhanced the memory window but reduced the endurance of SET/RESET operations. The energy filtered images by TEM showed asymmetric oxygen accumulation at the Ti/HfO x interfaces. Subsequent heat treatment improved the endurance of SET/RESET operation of TiN/HfO2/Ti/HfO2/Pt/Ti stacks.

Chitinase (EC 3.2.1.14) was isolated from the culture filtrate of Streptomyces sp. M-20 and purified by ammonium sulfate precipitation, DEAE-cellulose ion-exchange chromatography, and Sephadex G-100 gel filtration. No exochitinase activity was found in the culture filtrate. The molecular mass of the purified chitinase was 20 kDa, estimated by a sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and was confirmed by activity staining with Calcofluor White M2R. Chitinase was optimally active at pH of 5.0 and at 30 degrees C. The enzyme was stable from pH 4 to 8, and up to 40 degrees C. Among the metals and inhibitors that were tested, the Hg(+), Hg(2+), and p-chloromercuribenzoic acid completely inhibited the enzyme activity. The chitinase activity was high on colloidal chitin, chitotriose, and chitooligosaccharide. The purified chitinase showed antifungal activity against Botrytis cinerea, and lysozyme activity against the cell wall of Botrytis cinerea.

This paper proposes a design method of the position, velocity, and current controller for a hall sensored BLDC motor using TMS320F2812, a velocity estimation algorithm using a hall sensor, and a robust controller design method for an actuator system with uncertainties. The actuator for missiles requires high precision, fast response, and smaller size. The controller of the actuator should also satisfy these requirements. Although the analog controller provide precise control and fast response, the implementation of control algorithm and the modification of controller design are not easy. However, the digital controller solves these difficulties of the analog controller, since it implement the control algorithm as software. Moreover, it is easy to simulate under MATLAB/SIMULINK with the digital controller, which makes the digital controller more preferred.

We have observed net electron transport at zero bias, induced by surface acoustic wave (SAW), through a double-walled carbon nanotube on top of a GaAs substrate. As gate voltage varied, the SAW-induced current showed quasiperiodic oscillations ranging from positive to negative values. Such zero-bias oscillations were found to be closely related with the Coulomb oscillation at finite bias. SAW-induced ratchet pumping could explain our observations.

Occupational lung disease comprises a wide variety of disorders caused by the inhalation or ingestion of dust particles or noxious chemicals. These disorders include pneumoconiosis, asbestos-related pleural and parenchymal disease, chemical pneumonitis, occupational infection, hypersensitivity pneumonitis, and organic dust toxic syndrome. Most of these disorders produce diffuse lung disease. Although many of the disorders can be detected at chest radiography, high-resolution computed tomography (CT) has been shown to be superior to chest radiography in depicting parenchymal, airway, and pleural abnormalities. Some occupational lung diseases have characteristic radiologic features suggesting the correct diagnosis, whereas in others, a combination of clinical features, related occupational history, radiologic findings, and literature supporting an association between the exposure and the disease process is required for diagnosis. With advances in chest radiology, including high-resolution CT, radiologists play a key role in the clinical evaluation of occupational lung diseases and should continue their involvement in the diagnosis and treatment of these diseases.

Purpose: To assess the usefulness of three-dimensional CT portography using a standardized maximum intensity projection (MIP) technique for the evaluation of portosystemic collaterals in cirrhotic patients. Materials and Methods: In 25 cirrhotic patients with portosystemic collaterals, three-phase CT using a multidetector-row helical CT scanner was performed to evaluate liver disease. Late arterial-phase images were transferred to an Advantage Windows 3.1 workstation (Gener Electric). Axial images were reconstructed by means of three-dimensional CT portography, using both a standardized and a non-standardized MIP technique, and the respective reconstruction times were determined. Three-imensional CT portography with the standardized technique involved eight planes, namely the spleno-portal confluence axis (coronal, lordotic coronal, lordotic coronal RAO 30 degree, and lordotic coronal LAO 30 degree), the left renal vein axis (lordotic coronal), and axial MIP images (lower esophagus level, gastric fundus level and splenic hilum). The eight MIP images obtained in each case were interpreted by two radiologists, who reached a consensus in their evaluation. The portosystemic collaterals evaluated were as follows: left gastric vein dilatation; esophageal, paraesophageal, gastric, and splenic varix; paraumbilical vein dilatation; gastro-renal, spleno-renal, and gastrospleno-renal shunt; mesenteric, retroperitoneal, and omental collaterals. Results: The average reconstruction time using the non-standardized MIP technique was 11 minutes 23 seconds, and with the standardized technique, the time was 6 minutes 5 seconds. Three-dimensional CT portography with the standardized technique demonstrated left gastric vein dilatation (n=25), esophageal varix (n=18), paraesophageal varix (n=13), gastric varix (n=4), splenic varix (n=4), paraumbilical vein dilatation (n=4), gastro-renal shunt (n=3), spleno-renal shunt (n=3), and gastro-spleno-renal shunt (n=1). Using three-dimensional CT portography and the non-standardized MIP technique, the portosystemic collaterals demonstrated were similar to those demonstrated using the standardized technique. Additionally, howerer, the former revealed features not revealed by the latter, namely splenic varix (n=1), mesenteric collaterals (n=4), retroperitoneal collaterals (n=3), and omental collaterals (n=2). Conclusion: In patients with liver desease, three-dimensional CT portography using a standardized of MIP technique helps evaluate portosystemic collaterals, reduces interobserver bias, and saves reconstruction time.

Purpose: To evaluate the clinical usefulness of 3D volume-rendering (VR) CT laryngography during quiet breathing, Valsalva, and modified Valsalva maneuvers, in those with laryngeal and pyriform sinus lesions. Materials and Methods: Twenty-seven patients with various laryngeal and hypopharyngeal lesions were examined by means of four-channel multidetector-row helical CT (LightSpeed QX/i; GE Medical Systems, Milwaukee, Wis., U.S.A.) during quiet breathing, Valsalva, and modified Valsalva maneuvers. The protocol included 1.25-mm slice thickness, 3.75-mm rotation, 1.25 mm interval, and a pitch ratio of 3:1. Using an Advantage Windows 3.1 workstation (GE Medical Systems), 3D VR was generated in regions of interest, including all structures with a CT attenuation of between -1022 and -125 HU. Visual assessment of the findings of 3D CT laryngography, including the images obtained during the three different breathing maneuvers, were analyzed by three radiologists, who reached a consensus. These results were then compared with the findings of axial CT. The lesions discovered, in descending order of frequency, included laryngeal cancer (n=12), pyriform sinus cancer with an intact apex (n=6), pyriform sinus cancer with apex involvement (n=6), laryngeal papilloma (n=2), and hypopharyngeal obstruction with (n=1) and without (n=2) associated vocal cord palsy. In each case, the findings were confirmed by surgical biopsy, direct laryngoscopy, or CT. Results: 3D CT laryngography using the VR technique can supplement the information provided by axial images, and in the assessment of subglottic invasion and pyriform sinus apical invasion, its findings are consistent. In many of our cases, its use during quiet breathing was able to determine whether or not glottic cancer involved subglottic invasion. In laryngeal cancer cases, furthormore, modified Valasalva can be used to clarify the condition of the pyriform sinus apex. Dynamic-phase 3D CT laryngography can be used to elucidate the condition of a patient with vocal cord palsy. Conclusion: 3D CT laryngography is a new method for the visual diagnosis of vocal cord and laryngeal cancer. When employed after dynamic diagnosis, it is useful for the evaluation of subglottic extension, pyriform sinus apical invasion and vocal cord palsy, important indicators in the staging of cancer.

Background and Objectives:Aggressive antithrombotic therapy and transfemoral primary intervention during acute myocardial infarction (AMI) restricts the patient’s movement and may increase the risk of access site bleeding complications, and lengthen the duration of movement restriction and hospital stay. Transradial approach provides less bleeding complications and early ambulation. The purpose of this study is to know whether transradial primary intervention is safe and feasible in the patients with AMI. Materials and Method:From April 1998 to December 1998, transradial primary interventions were performed in the consecutive 28 patients (24 male, 57±7 years) by two experienced operators. The results were compared to the results of 44 (15 patients during same period, 29 during previous year) transfemoral primary interventions. Results:1) The success rates of transradial primary interventions was 93% (26/28) and comparable to 95% (42/44) of transfemoral primary interventions. 2) In transradial group, the time from the arrival of catheterization laboratory to arterial access and to reperfusion, the time from the arrival of emergency room to reperfusion were 8.1±3.4 minutes, 22.0± 5.3 minutes, and 71.7±9.2 minutes, respectively and comparable to 9.0±3.1 minutes, 21.7±5.3 minutes, and 68.9±8.1 minutes of transfemoral group, respectively. 3) The complications of the procedure were treated successfully during transradial interventions. 4) In transradial group, puncture site bleeding complications were absent though heparin was continued and mild ambulation was possible early after the procedure. The hospital stay of transradial group was 5.3±1.3 days and shorter than 7.7±4.2 days of transfemoral group. Conclusion: In the low risk patients with AMI, transradial primary intervention might be safe and feasible with acceptable time delay by the experienced operators. It might be effective to reduce access site bleeding complications and to initiate early ambulation, resulting in the shortened hospital stay. (Korean Circulation J 1999;29(2):153-160)