• 반도체디스플레이기술학회지
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• 제22권3호
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• pp.155-160
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• 2023

The potential performance benefits of Silicon Carbide(SiC) MOSFETs in high power, high frequency power switching applications have been well established over the past 20 years. In the past few years, SiC MOSFET offerings have been announced by suppliers as die, discrete, module and system level products. In high-voltage SiC vertical devices, major design concerns is the edge termination and cell pitch design Field Limiting Rings(FLR) based structures are commonly used in the edge termination approaches. This study presents a comprehensive analysis of the impact of variation of FLR and JFET region on the performance of a 3.3 kV SiC MOSFET during. The improvement in MOSFET reverse bias by optimizing the field ring design and its influence on the nominal operating performance is evaluated. And, manufacturability of the optimization of the JFET region of the SiC MOSFET was also examined by investigating full-map electrical characteristics.

• 대기
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• 제21권4호
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• pp.415-427
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• 2011

In this study, the impacts of land surface conditions, land cover (LC) map and leaf area index (LAI), on the short-range weather forecast over the East-Asian region were examined using Unified Model (UM) coupled with the MOSES 2.2 (Met-Office Surface Exchange Scheme). Four types of experiments were performed at 12-km horizontal resolution with 38 vertical layers for two months, July and August 2009 through consecutive reruns of 72-hour every 12 hours, 00 and 12 UTC. The control experiment (CTRL) uses the original IGBP (International Geosphere-Biosphere Programme) LC map and old MODIS (MODerate resolution Imaging Spectroradiometer) LAI, the new LAI experiment (NLAI) uses improved monthly MODIS LAI. The new LC experiment (NLCE) uses KLC_v2 (Kongju National Univ. land cover), and the new land surface experiment (NLSE) uses KLC_v2 and new LAI. The reduced albedo and increased roughness length over southern part of China caused by the increased broadleaf fraction resulted in increase of land surface temperature (LST), air temperature, and sensible heat flux (SHF). Whereas, the LST and SHF over south-eastern part of Russia is decreased by the decreased needleleaf fraction and increased albedo. The changed wind speed induced by the LC and LAI changes also contribute the LST distribution through the change of vertical mixing and advection. The improvement of LC and LAI data clearly reduced the systematic underestimation of air temperature over South Korea. Whereas, the impacts of LC and LAI conditions on the simulation skills of precipitation are not systematic. In general, the impacts of LC changes on the short range forecast are more significant than that of LAI changes.

• The Korean Journal of Physiology and Pharmacology
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• 제3권4호
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• pp.383-391
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• 1999

This study was carried out to determine whether the effects of an ${\alpha}_2-adrenoceptor$ agonist, clonidine, on mean arterial pressure (MAP) and heart rate (HR) are influenced by mild hypothermia. Experiments were performed in respiration-controlled and spontaneously breathing pentobarbital-anesthetized rats. Rectal temperature was maintained at $37.5{\pm}0.3^{circ}C$ for normothermic groups or at $35.2{\pm}0.3^{circ}C$ for mild hypothermic groups. Intravenous injection of clonidine (1 and 2 ${\mu}g/kg)$ produced depressor and bradycardic responses in spontaneously breathing rats under both normothermic and mild hypothermic condition: a decrease in MAP was not altered but bradycardic response was significantly augmented in the mild hypothermic group as compared with the normothermic group. Under the respiration-controlled condition, the hypotensive effect of clonidine $(2\;{\mu}g/kg)$ was reduced, whereas the bradycardic effect was increased in mild hypothermic rats as compared with normothermic rats. Both hypotensive and bradycardic effects of clondine $(2\;{\mu}g/kg)$ were blocked by pretreatment with an ${\alpha}_2-adrenoceptor$ antagonist, yohimbine (0.5 mg/kg), in both thermal conditions. Yohimbine (0.5 mg/kg, i.v.) alone produced signifcantly an increase in heart rate in the mild hypothermic group than in the normothermic group. Pretreatment with a muscarinic receptor antagonist, atropine methylnitrate (1 mg/kg, i.v.), attenuated the bradycardic effect of clonidine in the mild hypothermic group but not in the normothermic group. These results suggest that clonidine- induced bradycardia is amplified by mild hypothermia probably through an increased parasympathetic activity.

• Journal of Information Processing Systems
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• 제7권2호
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• pp.221-240
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• 2011

Vehicular networks are a promising application of mobile ad hoc networks. In this paper, we introduce an efficient broadcast technique, called CB-S (Cell Broadcast for Streets), for vehicular networks with occlusions such as skyscrapers. In this environment, the road network is fragmented into cells such that nodes in a cell can communicate with any node within a two cell distance. Each mobile node is equipped with a GPS (Global Positioning System) unit and a map of the cells. The cell map has information about the cells including their identifier and the coordinates of the upper-right and lower-left corner of each cell. CB-S has the following desirable property. Broadcast of a message is performed by rebroadcasting the message from every other cell in the terrain. This characteristic allows CB-S to achieve an efficient performance. Our simulation results indicate that messages always reach all nodes in the wireless network. This perfect coverage is achieved with minimal overhead. That is, CB-S uses a low number of nodes to disseminate the data packets as quickly as probabilistically possible. This efficiency gives it the advantage of low delay. To show these benefits, we give simulations results to compare CB-S with four other broadcast techniques. In practice, CB-S can be used for information dissemination, or to reduce the high cost of destination discovery in routing protocols. By also specify the radius of affected zone, CB-S is also more efficient when broadcast to a subset of the nodes is desirable.

• 대한안전경영과학회지
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• 제14권4호
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• pp.229-238
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• 2012

Within last 10 years, internet has become a daily activity, and humankind had to face the Data Deluge, a dramatic increase of digital data (Economist 2012). Due to exponential increase in amount of digital data, large scale data has become a big issue and hence the term 'big data' appeared. There is no official agreement in quantitative and detailed definition of the 'big data', but the meaning is expanding to its value and efficacy. Big data not only has the standardized personal information (internal) like customer information, but also has complex data of external, atypical, social, and real time data. Big data's technology has the concept that covers wide range technology, including 'data achievement, save/manage, analysis, and application'. To define the connected technology of 'big data', there are Big Table, Cassandra, Hadoop, MapReduce, Hbase, and NoSQL, and for the sub-techniques, Text Mining, Opinion Mining, Social Network Analysis, Cluster Analysis are gaining attention. The three features that 'bid data' needs to have is about creating large amounts of individual elements (high-resolution) to variety of high-frequency data. Big data has three defining features of volume, variety, and velocity, which is called the '3V'. There is increase in complexity as the 4th feature, and as all 4features are satisfied, it becomes more suitable to a 'big data'. In this study, we have looked at various reasons why companies need to impose 'big data', ways of application, and advanced cases of domestic and foreign applications. To correspond effectively to 'big data' revolution, paradigm shift in areas of data production, distribution, and consumption is needed, and insight of unfolding and preparing future business by considering the unpredictable market of technology, industry environment, and flow of social demand is desperately needed.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제17권2호
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• pp.435-449
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• 2023

The state-of-the-art video-based point cloud compression(V-PCC) has a high efficiency of compressing 3D point cloud by projecting points onto 2D images. These images are then padded and compressed by High-Efficiency Video Coding(HEVC). Pixels in padded 2D images are classified into three groups including origin pixels, padded pixels and unoccupied pixels. Origin pixels are generated from projection of 3D point cloud. Padded pixels and unoccupied pixels are generated by copying values from origin pixels during image padding. For padded pixels, they are reconstructed to 3D space during geometry reconstruction as well as origin pixels. For unoccupied pixels, they are not reconstructed. The rate distortion optimization(RDO) used in HEVC is mainly aimed at keeping the balance between video distortion and video bitrates. However, traditional RDO is unreliable for padded pixels and unoccupied pixels, which leads to significant waste of bits in geometry reconstruction. In this paper, we propose a new RDO scheme which takes 3D-Distortion into account instead of traditional video distortion for padded pixels and unoccupied pixels. Firstly, these pixels are classified based on the occupancy map. Secondly, different strategies are applied to these pixels to calculate their 3D-Distortions. Finally, the obtained 3D-Distortions replace the sum square error(SSE) during the full RDO process in intra prediction and inter prediction. The proposed method is applied to geometry frames. Experimental results show that the proposed algorithm achieves an average of 31.41% and 6.14% bitrate saving for D1 metric in Random Access setting and All Intra setting on geometry videos compared with V-PCC anchor.

• 환경정책연구
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• 제6권3호
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• pp.115-145
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• 2007

기존 국토환경성평가지도는 1:25,000 축척을 기본으로 하고 있어 전국 또는 광역 차원의 환경성 평가, 개발 가능지 분석, 거시적인 지역의 확인 및 중첩분석에 용이하다. 그러나 향후 국토통합정보시스템 연동 및 국소 지역 차원의 개발계획수립부문에서의 활용도를 높이기 위하여, 대축척 국토환경성평가지도의 구축이 요구된다. 본 연구의 목적은 기 구축되어 활용되고 있는 소축척(1:25,000 축척) 국토환경성평가지도의 동일 방법론 및 기본 주제도를 활용하여 대축척(1:5,000 축척) 국토환경성평가지도를 재구축하고, 자료형태를 벡터 형태 및 필지단위로 재평가하여 그 결과를 동일 연구지역의 소축척 국토환경성평가 지도와 비교 분석하는 데 있다. 또한 대축척 국토환경성평가지도를 동일한 지역 및 분석 단위를 가지는 토지적성평가와 비교하여 등급별 분포를 비교 분석 하였으며 이를 통하여 대축척 국토환경성평가지도 구축을 위한 기초정보를 분석하고 선행사항 도출 및 향후 활용방안을 제시하였다. 연구결과, 기 구축된 연구지역의 소축척 국토환경성평가지도 등급별 면적 비율은 1등급 23.3%, 2등급 29.4%, 3등급 23.9% 4등급 11.7%, 5등급 11.8%를 보이고 있다. 신규 구축된 연구지역의 대축척 국토환경성평가지도 등급별 면적 비율은 1등급 29.3%, 2등급 21.7%, 3등급 17.2%, 4등급 7.1%, 5등급 24.7%로 나타났으며 유사한 결과를 보이고 있음을 확인하였다. 또한 토지적성평가와의 일치도 비교분석 결과에서는 1등급 33.05%, 2등급 12.92%, 3등급 15.05%, 4등급 36.93%, 5등급 53.28%가 일치하는 것으로 나타났다. 대축척 국토환경성평가지도를 구축하기 위해서는 기존의 소축척에서 사용되던 주제도들이 우선적으로 1:5,000 축척으로 구축, 지적 기반의 필지단위로 변경 및 세분류 토지피복도 구축 등의 선행사항이 수행되어야 한다. 또한 대축척 국토환경성평가지도의 구축을 보다 효율적으로 수행하기 위해서 기존 주제도의 활용 구분 및 토지적성평가와의 연계를 제안하였다. 본 연구는 대축척 국토환경성평가지도를 처음으로 구축한 사례이며, 이러한 결과 및 경험을 바탕으로 실제 전국단위 대축척 구축과정에서의 선행사항 및 효율적인 구축방안을 모색하였다. 그러나 본 연구에서 도출된 구축방안이 대축척 국토환경성평가지도를 구축하는 모든 현황 및 과정을 반영하였다고는 볼 수 없다. 따라서 향후에 본 연구에서 도출된 결과를 실제 구축과정에 적용하기 위해서는 대축척 구축에 대한 체계적인 범주화 작업 및 세부 작업지침 등을 포함한 보다 본격적인 논의가 필요하다.

• 한국생물정보학회:학술대회논문집
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• 한국생물정보시스템생물학회 2004년도 The 3rd Annual Conference for The Korean Society for Bioinformatics Association of Asian Societies for Bioinformatics 2004 Symposium
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• pp.131-137
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• 2004

DNA 단계에서의 유전자의 증폭과 소실은 종양의 발생과 진행에 중요한 역할을 한다. 유전자의 변화를 관찰하기 위해서 Comparative Genomic Hybridization(CGH) 기술이 많이 이용되어져 왔다. 최근에는 이러한 CGH 기술을 응용하여 cDNA microarray 를 이용한 고밀도 CGH(Microarray-CGH) 기술이 보고 되고 있다. Microarray-CGH 에서 유전자별 변화 정도를 유전자의 log-비의 값의 변화 정도와 염색체 위치 정보를 이용하여 DNA 단계에서의 유전자의 변화 정도를 확인 할 수 있다. 또한 동일한 유전자의 칩을 사용하여 RNA단계에서의 발현 양상과 직접 비교할 수 있는 장점이 있다. 현재 microarray 분석법은 많이 개발되고 실용화 되고 있으나 Microarray-CGH 분석을 위한 프로그램들은 아직 초보 단계며, 생물학자들이 사용하기 힘들고, 프로그램에 분석 자료를 적용하기 어려운 경향이 있다. 위와 같은 단점을 보완하기 위해서 개발된 CAMVS(V1.0) 프로그램은 S-plus(2000)을 기반으로 개발하였고, 복잡한 분석보다는 모든 결과들을 이미지화 할 수 있으며 파일로 결과를 쉽게 확인할 수 있도록 디자인하였다. CAMVS(V1.0)는 전체 염색체를 각 실험별로 비교 분석하는 부분, 특정 염색체를 특정 실험별로 비교 분석하는 부분과 실험간의 차이를 통계적으로 비교 분석하는 3 가지 카테고리로 구성되어 있다. 쉬운 알고리즘과 사용의 편리함, 분석결과의 다양한 그래픽, 새로운 알고리즘 추가의 용이성 등이 CAMVS(V1.0)가 가지고 있는 장점이며, Microarray-CGH를 분석하는데 아주 유용한 분석 도구이다.

• 한국지리정보학회지
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• 제24권1호
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• pp.112-125
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• 2021

해양공간계획은 해양을 체계적이고 합리적으로 관리하기 위해 9가지 용도구역으로 지정한다. 그 중 하나가 어업활동의 보호와 육성을 비롯한 수산물의 지속 가능한 생산을 위해 필요한 어업활동 보호구역이다. 본 연구는 V-Pass 자료를 활용하여 어업활동 지도를 제작하고 어업활동 밀집 공간을 도출함으로써 어업활동보호구역 지정에 필요한 요소 중 하나인 어업활동 공간을 정량적으로 파악하고자 한다. 이를 위해 V-Pass 자료를 정적 정보와 동적 정보가 결합된 데이터셋 구축, 어선 속도 계산, 어업활동 지점 추출, 비어업활동 공간 내의 자료 제거와 같은 전처리를 수행하였다. 최종적으로 선별된 V-Pass 점 자료를 이용하여 커널밀도추정으로 어업활동 지도를 제작하고 어업활동이 밀집된 공간을 분석하였다. 또한 어선의 업종과 계절에 따라 어업활동의 공간분포는 차이가 있음을 확인하였다. 본 연구를 통해 수행한 대용량 V-Pass 자료의 전처리 기법과 어업활동의 공간밀도 분석 방법은 향후 어업활동에 대한 공간특성평가 연구에 기여할 것으로 기대된다.

• 한국연소학회:학술대회논문집
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• 한국연소학회 2014년도 제49회 KOSCO SYMPOSIUM 초록집
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• pp.379-381
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• 2014

Influence of fuel concentration gradient was investigated near flame extinction limit in buoyancy-suppressed non-premixed counterflow flame with triple co-flow burner. The use of He curtain flow produced a microgravity level of $10^{-2}-10^{-3}g$ in He-diluted non-premixed counter triple co-flow flame experiments. Flame stability map was presented based on flame extinction and oscillation near extinction limit. The stability map via critical diluent mole fraction with global strain rate was represented by varying outer and inner He-diluted mole fractions. The flame extinction modes could be classified into five: an extinction through the shrinkage of the outmost edge flame forward the flame center with and without self-excitation, respectively ((I) and (II)), an extinction via the rapid expansion of a flame hole while the outmost edge flame is stationary (III), both the outermost and the center edge flames oscillate, and then a donut shaped flame is formed or the flame is entirely extinguished (IV), a shrinkage of the outermost edge flame without self-excitation followed by shrinking or sustain the inner flame (V).