• JSTS:Journal of Semiconductor Technology and Science
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• v.3 no.1
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• pp.13-20
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• 2003

Both MgO and $Sc_2O_3$ are shown to provide low interface state densities (in the $10^{11}{\;}eV^{-1}{\;}cm{\;}^{-2}$ range)on n-and p-GaN, making them useful for gate dielectrics for metal-oxide semiconductor(MOS) devices and also as surface passivation layers to mitigate current collapse in GaN/AlGaN high electron mobility transistors(HEMTs).Clear evidence of inversion has been demonstrated in gate-controlled MOS p-GaN diodes using both types of oxide. Charge pumping measurements on diodes undergoing a high temperature implant activation anneal show a total surface state density of $~3{\;}{\times}{\;}10^{12}{\;}cm^{-2}$. On HEMT structures, both oxides provide effective passivation of surface states and these devices show improved output power. The MgO/GaN structures are also found to be quite radiation-resistant, making them attractive for satellite and terrestrial communication systems requiring a high tolerance to high energy(40MeV) protons.

• BMB Reports
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• v.47 no.5
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• pp.286-291
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• 2014

Inoculation of mice with the murine NFSA cell line caused the formation of large tumors with necrotic tumor cores. FACS analysis revealed accumulations of $CD11b^+$ cells in the tumors. Microarray analysis indicated that the NFSA cells expressed a high level of the pro-inflammatory factor interleukin-18 (il-18), which is known to play a critical role in macrophages. However, little is known about the physiological function of IL-18-stimulated macrophages. Here, we provide direct evidence that IL-18 enhances the phagocytosis of RAW264 cells and peritoneal macrophages, accompanied by the increased expression of tumor necrosis factor (tnf-${\alpha}$), interleukin-6 (il-6) and inducible nitric oxide synthase (Nos2). IL-18-stimulated RAW264 cells showed an enhanced cytotoxicity to endothelial F-2 cells via direct cell-to-cell interaction and the secretion of soluble mediators. Taken together, our results demonstrate that tumor-derived IL-18 plays an important role in the phagocytosis of macrophages and that IL-18-stimulated macrophages may damage tumor endothelial cells.

• Journal of Korea Foundry Society
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• v.17 no.2
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• pp.170-179
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• 1997

A noble technique has been developed for fabricating in situ formed $TiC_p/Al$ composites. In this process, fairly stable TiC particles were in situ synthesized in liquid aluminum by the interfacial reaction between an Al-Ti melt and SiC, which is a comparatively unstable carbide from the view-point of thermodynamics. It is possible in the present process to generate TiC particles of nearly 1 ${\mu}m$ in diameter, even utilizing SiC of 14 ${\mu}m$ as raw material. However, the dispersion behavior of TiC particles in the matrix depends on the size of the raw material SiC. Decomposing finer SiC makes the dispersion of TiC particles more uniform and the mechanical properties of composites are improved accordingly. The structure of in situ composites and their mechanical properties are affected by the fabrication temperature and the stirring time. It has been found that the most suitable condition for fabrication should be applied depending on the size of the raw material, even if the same kinds of carbide are used. Furthermore, although Al-Ti-Si system intermetallic compounds are detected in a $TiC_p/Al-Si$ composite which is fabricated by conventional melt-stirrng method, these compounds can not be observed in a $TiC_p/Al-Si$ composite made by this in situ production method. Hence the mechanical properties of the in situ $TiC_p/Al-Si$ composite are superior to those of the conventional $TiC_p/Al-Si$ composites.

• Korean Journal of Ecology and Environment
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• v.38 no.4 s.114
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• pp.439-444
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• 2005

The environmental quality of the middle-reach of the Yahagi River has deteriorated in recent years. The nutrient dynamics within the reach were investigated to explain the changes. Seasonal pattern of $NO_3\;^--N$ concentration tended to stay low from April or May through July or August and then increased till winter or early spring, although there were peaks during high flow periods in mid-September, 2000 and late-August, 2001. No clear seasonal changes were observed in $PO_4\;^{3-}-P$ concentration. In the bimonthly records from 1980-2002, the DIN concentrations on January and March were higher than other months whereas the average daily flows on January and March were lower than they were in other months. The mean DIN concentration showed a high negative correlation with the median of average daily flow. In the past 50 years, the average concentration of DIN (excluding nitrite) was 0.21 mg $L^{-1}$ in 1952-1953. The concentration was about twice this high around 1980, and it is about three times this high at present. On the other hand, the average concentration of $PO_4\;^{3-}-P$ was below the limit of detection in 1952-53. However, it increased to almost 0.03 mg $L^{-1}$ around 1980, then decreased to approximately 0.016mg $L^{-1}$ at present. Our results suggest that the increasing DIN concentration is one of the causes of environmental change in the Yahagi River. We conclude that controlling the DIN concentration is essential for improving the river environment.

• The Bulletin of The Korean Astronomical Society
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• v.35 no.1
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• pp.48.2-48.2
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• 2010

Korean-Japanese Planet Search Program has been carried out since 2005 to search for planets around intermediate-mass giant stars (1.5-5.0 solar masses) by an international collaboration between Korean and Japanese researchers. In this program, we have been carrying out a precise radial velocity survey of about 190 G-type giant stars (6.21.9 solar masses) giant stars. These results extend the planet mass distribution of massive intermediate-mass stars to higher and lower mass region, and may further constrain substellar system formation mechanisms. We report the recent results and current status of Korean-Japanese Planet Search Program.

• Journal of the KSME
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• v.44 no.1
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• pp.27-27
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• 2004

미국 국방부 소속 육군차량사업부(National A Automotive Center)는 대체에너지를 이용한 군용 차량 개발을 위해 Michigan 주 Rochester Hills에 위치한 E Energy Conversion Devices(ECD) 사와 일부 기술 개발 에 대한 기술 제휴를 한다고 발표했다. 국방부는 태양전 지와 수소를 연료로 사용하는 대체에너지 차량을 개발하 기 위해 ECD에 1단계 연구에 필요한 연구비를 지원했다. 이번 연구에는 연료전지를사용한차량개발을위해 5 500,$\omega$0달러가 투자되는데, Texaco Ovollic Hydrogen S Systems(TOHC)의 고체 휴대용 수소 연료와 채충천 (refueling) 시스탬이 주요 개발 목표로 설정됐다. ECD의 역할은 최근 개발된 Toyota Prius에 시범 적으로 장착된 저압 고체형 수소 저장 시스템의 기술을 군용 차량에 알맞게 전환시키는 것이다. TOHC와 ECD가 개발한 고체형 수소 보관 시스댐은 고압을 요구하는 연료전지 차량의 수소 저 장 시스템이 갖고 있는 많은 문제점들을 해결할 수 있을 것으로 기대되는 연료전지를 이용한 엔진 개발 중 최신 기술이다. 특히 전투 상황에서 차량이 폭발하기 쉬운 수소 저장 탱크를 장착한 채 전 장으로간다는 것은적에게 노출 될 경우자살과마찬가지인 치명적인 피해를 입을수 있다. 이 프로젝트의 개요를 살펴보면, 수소 저장 시스템은 적어도 약 lOkg의 수소를 적은 용적 내에 낮은 압력에서 안전하게 고체 상태로 저장할 수 있다. 이 고체 저장 용기는 하루에 두 번 1.7kg의 수소를 10분 이내에 재급유할 수 있다. 수소는대부분고압가스형태나저온액체 형태로보관된다. 기체나액체 형태의 수소는 연료전 지에 사용되기에는 적합하지 않은 점이 많다. Ovonie 수소 저장 방법은 수소를 저압 고체 형태 ( (metal hydride)로 보관하는 방법으로, 고압 기체나 저온 액체가 갖고 있는 많은 문제점들을 해결 할수있다. 그림을 참조하면 고체 형태의 수소 보관 방법이 다른 보관 방법에 비교해 단위 체적당 최고 6배 많은수소질량을보관할수 있다. 이 고체 형태의 보관방법은수소가적절한합금과평형 압력 이 상의 환경에 놓일 경우 합금에 홉착되는 현상을 이용하고 있다. 수소를 흡수한 합금은 새로운 특성 을 가진 metal hydride로 변하게 된다. 이 과정 에서 열이 부산물로 발생한다. 반대로 수소를 metal hydride로부터 분리시키기 위해서는 합금을 가열해야 한다.

• International Journal of Automotive Technology
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• v.4 no.2
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• pp.65-75
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• 2003

A HEV evaluation program, funded by ADEME, was carried out by a group of Laboratories of different specialties in order to evaluate and compare consumption, emission and component technologies of the three first HEVs put on the market (Toyota Prius, Nissan Tino and Honda Insight). This paper presents the results obtained until now. These results show good consumption and emission performance of the tested vehicles compared to conventional ones. The energy management seems to be globally the same for the three vehicles excepting for cold stans where the Insight allows a very earlier stop of the engine compared to the Tino and especially to the Prius. A mapping of the engine consumption of the Prius and the Insight was performed in order to furnish data for the simulation models. The Permanent Magnet motors of the Prius and Tino have different number of pair poles and then different emf at a given speed. The low emf values of the Prius allow operation at high speed with less field weakening control than for the Tino. The inverters of the Prius and the Tino, controlled by a PWM at respectively 5 kHz and 7 kHz switching frequency, are made of IGBTs with high commutation performances.

• Transactions of the Korean Society of Automotive Engineers
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• v.19 no.3
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• pp.73-82
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• 2011

Most of countries start to restrict the emission gases of vehicles especially CO2 because of the global warming. Many vehicle companies including Toyota have launched various HEVs to satisfy the restriction laws and to improve the vehicle's efficiency. However, development for heavy-duty hybrid system is not plentiful rather than the passenger car. In this study, we choose the optimal size of engine, motor and battery for heavy-duty hybrid systems using dynamic programming. Also we analyze the correlation of the system's cost and efficiency because the added cost of vehicle to make the hybrid system is very important factor for the manufacturing companies. Finally, this study suggests a method to choose the appropriate system components size considering its performance and the cost. With this method, it is possible to select the component size for various systems.

• Journal of Korea Technology Innovation Society
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• v.14 no.1
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• pp.85-108
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• 2011

Under Ford system, corporations sought to maximize the economies of scale by raising the production efficiency. It aims to lower the production cost by increasing the quantity of output. But in the era of market flux and uncertainty, however, such strategies can no longer be sustained. Replacing the structures of Ford system, Toyota was able to accelerate the pace of process innovation and product innovation. Related to this innovation is JIT, new model development, modularization. The firm's reliance on flexible production technology provides opportunities to expand her production basis to foreign countries successfully. The main objective of this paper is to explore the contribution of process innovation to profit-capital ratio. The model is estimated using a time-series data of 18 years from 1990 to 2007 of auto production industry in korea. An Implication of this estimation shows that process innovation explains a significant portion of profit-capital ratio.

• Journal of Gastric Cancer
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• v.22 no.1
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• pp.56-66
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• 2022

Purpose: Nutritional problems after gastrectomy affect continuation of postoperative chemotherapy. There have been no studies limited to total gastrectomy, which is particularly prone to nutritional problems. In this study, we aimed to investigate the factors that predict the continuation of postoperative chemotherapy. Materials and Methods: We included 101 patients who underwent curative total gastrectomy and postoperative chemotherapy at Hiroshima Memorial Hospital. The effects of 37 factors, including perioperative inflammatory, nutritional, and tumor status, on the persistence of postoperative chemotherapy were analyzed. Results: In univariate analysis of preoperative factors, age, carbohydrate antigen 19-9, platelet-to-neutrophil ratio, Onodera's prognostic nutritional index (PNI), controlling nutritional status score, and nutritional risk screening (NRS-2002) score were significantly associated with the duration of postoperative chemotherapy. In multivariate analysis of preoperative factors, age (≥74 years) was an independent factor for a shorter duration of postoperative chemotherapy (hazard ratio [HR], 5.24; 95% confidence interval [CI], 2.19-12.96; P<0.01). In univariate analysis of factors before postoperative chemotherapy, intraoperative blood loss, perioperative weight loss rate, postoperative performance status, PNI, albumin-to-bilirubin index, and NRS-2002 score were significantly associated with the duration of postoperative chemotherapy. In multivariate analysis of factors before postoperative therapy, age (≥74 years) (HR, 5.75; 95% CI, 1.90-19.49; P<0.01) and PNI (<39) (HR, 3.29; 95% CI, 1.26-8.56; P=0.02) were independent factors for a shorter duration of postoperative chemotherapy. Conclusions: Age and PNI are useful predictors of postoperative chemotherapy intolerance after total gastrectomy and may determine the treatment strategy and timing of chemotherapy initiation.