4H-SiC Schottky Barrier Diode Using Double-Field-Plate Technique

김태완,심슬기,조두형,김광수,Kim, Taewan,Sim, Seulgi,Cho, Dooyoung,Kim, Kwangsoo The Institute of Electronics and Information Engin 2016 전자공학회논문지 Vol.53 No.7

탄화규소(Silicon Carbide)는 와이드 밴드 갭 물질로써 실리콘(Si)에 비해 고전력, 고주파, 고온 소자용 반도체 물질로서 각광받고 있다. 탄화규소를 이용하여 만든 반도체 소자 중 특히 쇼트키 배리어 다이오드는 현재 가장 많이 사용되는 전력반도체 소자로써 스위칭 속도가 매우 빠르고 낮은 온저항 특성을 가지는 소자이다. 하지만 컨텍 엣지에서의 전계집중으로 인해 항복전압이 낮아지는 단점이 있다. 이를 해결하기 위해 다양한 엣지 터미네이션 기술이 제안되고 있는데, 본 논문에서는 최적의 항복전압을 갖기 위한 이중 필드 플레이트(Double Field Plate) 소자 구조를 제안하였다. 측정결과 제작한 소자는 온저항을 유지한 채 38% 향상된 항복전압을 나타내었다. 제안한 소자 특성 검증을 위해 소자를 설계 및 제작한 후 전기적 특성을 측정하였으며, 이중 필드 플레이트 구조는 길이와 두께가 서로 다른 필드 플레이트를 겹쳐 올림으로써 구현하였다. Silicon carbide (SiC) has received significant attention over the past decade because of its high-voltage, high-frequency and high-thermal reliability in devices compared to silicon. Especially, a SiC Schottky barrier diode (SBD) is most often used in low-voltage switching and low on-resistance power applications. However, electric field crowding at the contact edge of SBDs induces early breakdown and limits their performance. To overcome this problem, several edge termination techniques have been proposed. This paper proposes an improvement in the breakdown voltage using a double-field-plate structure in SiC SBDs, and we design, simulate, fabricate, and characterize the proposed structure. The measurement results of the proposed structure, demonstrate that the breakdown voltage can be improved by 38% while maintaining its forward characteristics without any change in the size of the anode contact junction region.

중층 종합병원 건물의 내진성능평가

김태완,추유림,김승래,Kim, Taewan,Chu, Yurim,Kim, Seung Rae 한국지진공학회 2017 한국지진공학회논문집 Vol.21 No.5

The building which are essential for disaster recovery is classified as a special seismic use group. Especially, achievement of seismic performance is very important for the hospital, so the hospital should be able to maintain its function during and right after an earthquake without significant damage on both structural and non-structural elements. Therefore, this study aimed at checking the seismic performance of a hospital building, but which was limited to structural elements. For the goal, a plan with a configuration of general hospitals in Korea was selected and designed by two different seismic-force-resisting systems. In analytical modeling, the shear behavior of the wall was represented by three inelastic properties as well as elastic. Nonlinear dynamic analyses were conducted to evaluate the performance of structural members. The result showed that the performance of shear walls in the hospital buildings was not satisfied regardless of the seismic-force-resisting systems, while the demands on the beams and columns did not exceed the capacities. This is the result of only considering the shear of the wall as the force-controlled action. When the shear of the wall was modeled as inelastic, the walls were yielded in shear, and as the result, the demands for frames were increased. However, the increase did not exceed the capacities of the frames members. Consequently, since the performance of walls is significant to determine the seismic performance of a hospital building, it will be essential to establish a definite method of modeling shear behavior of walls and judging their performance.

기존 저층 필로티 건물의 스펙트럼 변위 기반 손상도 기준 개선

김태완,Kim, Taewan 한국지진공학회 2021 한국지진공학회논문집 Vol.25 No.5

The Ministry of the Interior and Safety in Korea developed seismic fragility function for various building types in 2009. Damage states for most building types were determined by structural analyses of sample models and foreign references because actual cases damaged by earthquakes rarely exist in Korea. Low-rise, piloti-type buildings showed severe damage by brittle failure in columns due to insufficient stirrup details in the 2017 Pohang earthquake. Therefore, it is necessary to improve damage state criteria for piloti-type buildings by consulting actual outcomes from the earthquake. An analytical approach was conducted by developing analysis models of sample buildings reflecting insufficient stirrup details of columns to accomplish the purpose. The result showed that current spectral displacements of damage states for piloti-type buildings might be too large to estimate actual fragility. When the brittle behavior observed in the earthquake is reflected in the analysis model, one-fourth through one-sixth of current spectral displacements of damage states may be appropriate for existing low-rise, piloti-type buildings.

피로인산 전해질에서 양극산화를 통한 알루미늄 3104 합금 나노섬유 산화물 형성

김태완,이기영,Kim, Taewan,Lee, Kiyoung 한국전기화학회 2021 한국전기화학회지 Vol.24 No.1

본 연구에서는 산업에서 많이 이용되는 알루미늄 3104H18 금속을 양극산화하여 다공성 나노구조 및 나노섬유 구조의 알루미늄 산화막을 형성하였다. 양극산화를 위한 전해질은 피로인산(H4P2O7)과 증류수를 혼합하여 사용하였다. 양극산화 진행 시 전해질의 농도, 온도, 인가전압과 같은 다양한 변수를 통해 다공성 알루미늄 산화막과 나노섬유 구조를 형성할 수 있었다. 나노섬유 구조를 형성하기 위해서는 피로인산 전해질 농도가 75 wt%, 인가전압이 30 V, 20℃의 양극산화 온도가 최적 조건임을 밝혀냈다. 인가전압이 40 V 이상이 되었을 때는 산화물의 용출속도의 증가 또는 높아진 전압으로 인한 채널벽의 두께증가로 인하여 다공성 나노구조의 형태가 나타난다는 것을 확인했다. 본 연구를 통하여 전해질의 농도, 인가전압 및 온도에 따른 산화물의 형성 및 용해반응이 평형을 이루었을 때 가장 나노섬유가 잘 형성된 알루미늄 산화막을 형성할 수 있음을 밝혔다. In this study, we investigated the formation of the metal oxide nanostructure by anodization of aluminum 3104H18 alloy. The anodization was performed in pyrophosphoric acid (H4P2O7) electrolyte. By the control of anodization condition such as concentration of electrolyte, anodization temperature and applied voltage, nanoporous or nanofiber structures were obtained. The optimal anodization condition to form nanofiber structures are 75 wt% of H4P2O7 at 30 V and 20℃. When anodization was performed at over 40 V, nanoporous structures were formed due to accelerated dissolution reaction rate of nanofiber structures or increasing thickness of channel wall.

노동시장 임금격차가 소득분배 및 빈곤에 주는 영향

김태완(Kim, Taewan),이주미(Lee, Jumi) 충북대학교 생활과학연구소 2020 생활과학연구논총 Vol.24 No.1

In this article, we analyzed the relation among wage gap, income distribution, and poverty in the labor market using the Korean welfare panel survey. According to the results of the analysis, the wage gap between men and women is decreasing as a result of cross-analysis, but the difference in education level, company size, and wage difference between regular and non-regular workers is increasing. In the case of a workplace with less than five people, the poverty experience rate is high. Dynamically, the proportion of both men and women who are self-employed with lower than middle school education has experienced a significant increase in long-term or repeated poverty. According to the company size, long-term poverty rate was 14.9% for men and 16.6% for women when the strength of the workplace was less than 5 for both men and women, and it was analyzed to be more vulnerable to poverty than other groups. Further, it was analyzed that a small business or small company was highly likely to experience poverty repeatedly. This result was the same even based on the income quintile. To improve the distribution due to the wage gap in the labor market, the same wage system for the same labor needs to be established. To reduce the difference in wages by company size, the government needs to develop policies and support to reduce the expenditure of workers in small businesses.

유엔해양법협약 레짐과 동아시아 갈등

김태완(Kim, Taewan) 동아시아국제정치학회 2007 국제정치연구 Vol.10 No.1

고주기 피로 모델을 이용한 접촉 피로 수명에 관한 연구

김태완(Taewan Kim),이상돈(Sangdon Lee),조용주(Yongjoo Cho) 한국자동차공학회 2004 한국자동차공학회 지부 학술대회 논문집 Vol.- No.-

In this study, using high cycle fatigue(HCF) criteria, the simulation of rolling contact fatigue is conducted under elliptical contact. The HCF criteria fall into three categories: the critical plane approach, the stress invariant approach and the approach based on the mesoscopic scale. The accurate calculation of contact stresses and subsurface stresses is essential to the prediction of crack initiation life. Contact stresses are obtained by contact analysis of a semi-infinite solid based on the use of influence functions and the subsurface stress field is obtained using rectangular patch solutions. The simulation results show that the critical load is decreasing rapidly and the site of crack initiation also moves rapidly to the surface from the subsurface when the friction coefficient exceeds a specific value for all of three fatigue criteria.

건설기계 자율주행을 위한 Vortex Studio 시뮬레이션 환경 구축 및 경로 추종 평가

김태완(Taewan Kim),김승희(Seunghee Kim),강연식(Yeonsik Kang) 한국자동차공학회 2023 한국자동차공학회 학술대회 및 전시회 Vol.2023 No.11

19대 총선 집합자료를 이용한 당선 가능성 예측과 투표율의 상관관계 분석

김태완(Taewan Kim) 21세기정치학회 2012 21세기 정치학회보 Vol.22 No.3

This study analyzes the correlation between voting participation and voter's prediction on the availability with aggregate-level data on the 19th Korean general election. To test the hypothesis based on the Voting Efficacy Model, set several variables and choose the 'Multi-party Margin(MPM) Index' as the tool of measuring the effect of competition. The result of this analysis shows the MPM adjusted by HHI is strong variable to measure degree of competition of the Korean district system. And it also shows the close competition between candidates has the positive correlation with voter turnout and improves voter's individual voting efficacy.

시민의 비선거적 정치참여에 대한 영향요인 분석

김태완(Taewan Kim) 21세기정치학회 2015 21세기 정치학회보 Vol.25 No.4

The purpose of this study is to find the influencing factors on the non-electoral participation which is essential for the maintenance and development of democracy. It assumed the theoretic causal relationship among factors dealt with in previous studies, and tried structural equation modeling analysis to verify this. As a result, the structure which non-electoral participation of citizens was determined in accordance with the assessment of the economic situation was observed. The structure which the more positive the assessment of the economic situation was, the higher interests about community and politics were, and the more actively citizens participated in the non-electoral political behaviors was observed. In addition, the more young citizens were, the more actively participated in them. The level of non-electoral participation were very low. To overcome this realities, it may be necessary to increase social spending to overcome income inequality and unemployment. It may need the activation of local politics, local press’s effort to develop local issue and to form regional opinion. And it may be necessary to find alternatives that make post democratization generation to maintain and develop their indigenous participatory culture through their unique information delivery and communication.