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AlGaN/GaN HEMT의 분극 현상에 대한 3D 시뮬레이션
정강민(Kang Min Jung),김재무(Jae Moo Kim),김희동(Hee Dong Kim),김동호(Dong Ho Kim),김태근(Tae Geun Kim) 大韓電子工學會 2010 電子工學會論文誌-SD (Semiconductor and devices) Vol.47 No.10
본 논문에서는 AlGaN/GaN HEMT의 분극에 의한 전기적인 특성과 구조적인 특성에 대해서 분석하였다. 몰 분율, AlGaN barrier 층의 두께의 물리적인 변화에 따라서 이차원 전자가스 채널의 농도 변화가 이루어지는 것을 바탕으로 DC 특성 및 분극을 고려한 최적화된 구조에 대해서 시뮬레이션을 진행하였다. AlGaN의 몰 분율이 0.3 몰에서 0.4 몰로 증가할수록 분극에 의한 bound sheet charge가 16 % 증가하며 그에 따라서 Id-Vd 특성 역시 37% 증가하게 된다. 또한 AlGaN 층의 두께가 17 ㎚에서 38 ㎚로 증가할수록 Id-Vd의 특성이 증가하다가 임계두께인 39 ㎚에 이르게 되면 AlGaN층의 relaxation에 의해서 급격하게 특성이 나빠지는 것을 알 수 있다. In this paper, we investigated the polarization effects on the electrical and structural characteristics of AlGaN/GaN HEMT. Both the Al mole-fraction and the barrier thickness of AlGaN, which determine the profiles of a two-dimensional electron gas, were simulated to obtain the optimum HEMT structure affecting the polarization effect. As a results, we found that the amount of bound sheet charges was increased by 16% and the maximum drain current density (ID,max) was increased by more than 37%, while Al mole fractions are changed from 0.3 to 0.4. We also observed a 37 % improvement in maximum drain current density (I<SUB>D</SUB>,max) by increasing AlGaN layer thickness from 17 to 38 ㎚. However when AlGaN layer thickness reached the critical thickness, DC characteristics were dramatically lowered due to 'bulk' relaxation in AlGaN layer.
TPL을 이용한 일단위 실거래 가격지수 산정방법에 관한 연구
류강민(Kang-Min Ryu),한제선(Je-Sun Han),정상준(Sang-Jun Jung),이창무(Chang-Moo Lee) 한국주택학회 2017 주택연구 Vol.25 No.2
2009년 국내에 아파트 실거래가 지수가 공표된 이후, 2016년에는 연립다세대 실거래가 지수가 추가로 공개되었다. 이들 지수의 특징 중 하나는 국내에서 표준화되어 대량 으로 공급된 공동주택을 대상으로 하여 거래쌍을 구성하기 쉽고, 개별특성 또한 파악하기 쉬워 지수를 산정하기에 용이하다는 것이다. 그러나 단독다가구 주택은 표준화되어 공급되지 않아 개별특성을 파악하기가 쉽지 않다. 또한 국내의 경우 아파트 위주로 공급되기 때문에 지수를 만들기 위한 표본이 상당히 부족한 실정이다. 또한 주택가격지수와 연관된 이슈 중의 하나는 주택가격지수가 주식과 같은 금융상품의 기초자산으로 역할을 할 수 있느냐는 것이다. 그러나 주택가격지수가 코스피 지수와 같이 금융상품의 기초자산이 되기 위해서는 투자자나 헷지를 원하는 시장참여자가 시장 변화에 민감하게 대처할 수 있도록 일별 지수가 산정되어야 한다. 그러나 지금까지의 주택가격지수는 자료의 한계로 인해 월별로만 산정되고 있다. 본 연구는 이러한 한계를 극복하고자 자료에 한계가 있을 때 지수를 산정할 수 있고, 일별로도 중위수를 이용하여 지수를 산정할 수 있는 방법인 Radar Logic사의 TPL 방법을 제시하고자 한다. Since the apartment sales price index using repeated sale data was introduced in 2009, the multi-family house price index was released in 2016. The two-type houses have good characteristics for making indices. For example they have lots of transaction data and lots of stock with standardized type for quality control. However, detached houses in Korea are not supplied in a standardized form and it is difficult to identify individual housing characteristics. Apart from this there is a lack of transaction data to generate sale price index of a detached house since the domestic housing market has been dominated by apartment. The other issue associated with the housing price index is whether the price index could reflect an underlying demand of financial asset such as a stock market. In order to estimate an underlying asset of capital market like the KOSPI index, a daily index should be considered so that the property investors who desire to hedge their investment can timely respond on the market change. Unfortunately, the house price index has been calculated in a monthly base due to a lack of transaction data. This study proposes the ‘TPL method’ of Radar Logic company, which calculates indices even when data exists in a small number and produces the index on a daily basis.
트렌치 구조의 소스와 드레인 구조를 갖는 AlGaN/GaN HEMT의 DC 출력특성 전산모사
정강민,이영수,김수진,김동호,김재무,최홍구,한철구,김태근,Jung, Kang-Min,Lee, Young-Soo,Kim, Su-Jin,Kim, Dong-Ho,Kim, Jae-Moo,Choi, Hong-Goo,Hahn, Cheol-Koo,Kim, Tae-Geun 한국전기전자재료학회 2008 전기전자재료학회논문지 Vol.21 No.10
We present simulation results on DC characteristics of AlGaN/GaN HEMTs having trench shaped source/drain Ohmic electrodes. In order to reduce the contact resistance in the source and drain region of the conventional AlGaN/GaN HEMTs and thereby to increase their DC output power, we applied narrow-shaped-trench electrode schemes whose size varies from $0.5{\mu}m$ to $1{\mu}m$ to the standard AlGaN/GaN HEMT structure. As a result, we found that the drain current was increased by 13 % at the same gate bias condition and the transconductance (gm) was improved by 11 % for the proposed AlGaN/GaN HEMT, compared with those of the conventional AlGaN/GaN HEMTs.
계단형 게이트 구조를 이용한 AlGN/GaN HEMT의 전류-전압특성 분석
김동호(Dong Ho Kim),정강민(Kang Min Jung),김태근(Tae Geun Kim) 大韓電子工學會 2010 電子工學會論文誌-SD (Semiconductor and devices) Vol.47 No.6
본 논문에서는 고출력 · 고이득 특성을 갖는 고전자이동도 트랜지스터 (high-electron mobility transistor, HEMT)를 구현하기 위하여 계단형 구조의 게이트 전극을 갖는 AlGaN/GaN HEMT를 제안하였고, 소자의 DC 특성의 향상 가능성을 확인하기 위하여 단일 게이트 전극을 갖는 HEMT 및 field-plate 구조의 게이트 전극을 갖는 HEMT 소자와의 특성을 비교 분석하였다. 상용 시뮬레이터를 통해 시뮬레이션 결과, 본 연구에서 제안한 계단형 구조의 게이트 전극을 갖는 AlGaN/GaN HEMT는 드레인 전압의 인가 시, 소자의 내부에서 발생하는 전계가 단일 게이트 전극을 갖는 HEMT에 비해 약 70% 정도 감소하는 특성을 갖는 것을 확인하였고, 전달이득 (transconductance, g<SUB>m</SUB>) 특성 역시 단일 게이트 전극구조의 HEMT나 field-plate 구조를 삽입한 HEMT에 비해 약 11.4% 정도 향상된 우수한 DC 특성을 갖는 것을 확인하였다. We present simulation results on DC characteristics of AlGaN/GaN HEMT having stair-type gate electrodes, in comparison with those of the conventional single gate AlGaN/GaN HEMTs and field-plate enhanced AlGaN/GaN HEMTs. In order to reduce the internal electric field near the gate electrode of conventional HEMT and thereby to increase their DC characteristics, we applied three-layered stacking electrode schemes to the standard AlGaN/GaN HEMT structure. As a result, we found that the internal electric field was decreased by 70% at the same drain bias condition and the transconductance (gm) was improved by 11.4% for the proposed stair-type gate AlGaN/GaN HEMT, compared with those of the conventional single gate and field-plate enhanced AlGaN/GaN HEMTs.
사다리꼴 게이트 구조를 갖는 고내압 AlGaN/GaN HEMT
김재무(Jae-Moo Kim),김수진(Su-Jin Kim),김동호(Dong-Ho Kim),정강민(Kang-Min Jung),최홍구(Hong Goo Choi),한철구(Cheol-Koo Hahn),김태근(Tae-Geun Kim) 대한전자공학회 2009 電子工學會論文誌-SD (Semiconductor and devices) Vol.46 No.4
본 논문에서는 항복 전압 특성을 향상시키기 위한 사다리꼴 게이트 구조의 AlGaN/GaN HEMT구조를 제안하였으며 그 실현 가능성을 2차원 소자 시뮬레이터를 통해 조사하였다. 사다리꼴 게이트 구조의 사용으로 드레인 방향의 게이트 모서리 부근에서 나타나는 전계의 집중을 효과적으로 분산되는 것이 시뮬레이션 결과에서 확인 되었다. 제안된 사다리꼴 게이트 AlGaN/GaN HEMT 소자 구조에서 2DEG 채널을 따라 형성되는 전계의 피크값은 4.8 MV/㎝ 에서 3.5 MV/㎝ 로 기존 구조의 AlGaN/GaN HEMT에 비해 30 % 가량 감소하였으며, 그 결과로 인해 항복 전압은 49 V 에서 69 V 로 40 % 가량 증가하였다. We propose a trapezoidal gate AlGaN/GaN high electron mobility transistor (HEMT) to improve the breakdown voltage characteristics and its feasibility is investigated by two-dimensional device simulations. The use of a trapezoidal gate structure appears to be quite effective in dispersing the electric fields concentrated near the gate edge on the drain side from the simulation result. We find that a peak value of the electric field along the 2-DEG channel is reduced by 30 %, from 4.8 to 3.5 MV/㎝, and thereby, the breakdown voltage (Vbr) of the proposed AlGaN/GaN HEMT is increased by about 40 %, from 49 to 69 V, compared to those of the standard AlGaN/GaN HEMT.
성인 상부위장관 질환군에서의 H . pylori 검출에 이용되는 검사법의 상호비교
한길성(Gil Sung Han),서대규(Dae Gyu Seo),신왕식(Wang Sik Shin),정재군(Jae Gun Jung),손호상(Ho Sang Shon),최정윤(Jung Yoon Choe),안기성(Ki Sung Ahn),배정동(Jung Dong Bae),박재복(Jae Bok Park),강민모(Min Mo Kang) 대한소화기학회 1996 대한소화기학회지 Vol.28 No.1
N/A Background/Aims: For the evaluation of recent reports that H. pylori infection plays a causative ro1e in the pathogenesis of upper gastrointestinal diseases, we studied the relationship between the presence of H. pylori infection in patient and asymptomatic volunteer groups, using histologic demonstration of the bacteria, CLO test, and serum H. pylori antibody titer. Calculation of sensitivity, specificity, and predictive value of CLO test and antibody detection rate in relation to histologic demonstration were also performed. Methods: We evaluated the detection rate of H. pylori infection by direct demonstration with special stain, CLO test, and IgG antibody titer by EIA method in 80 symptomatiq patients who were categorized by endoscopic findings into 24 patients with chronic gastritis, 22 patients with gastric ulcer, 20 patients with duodenal ulcer, 14 patients with gastric cancer, and 20 asymptomatic volunteers. Four or more biopsy specimens of gastric and duodenal mucosa were taken from each of the total 100 cases with gastrofibroscopy and then blood samples were also taken. Results: In sections stained by Warthin-Starry method, H. pylori was found 62.5% in the 80 patients group and 30.0% in the 20 asymptomatic volunteers group. The prevalence of H. pylori was the highest in gastric cancer group(71.4%). The prevalence of H. pylori in the patients with peptic ulcer and gastric cancer was significantly higher than the asymptomatic volunteer group(p0.05). Positive CLO test in the patient group was 77.5% and 35.0% in the 20 asymptomatic volunteers group. The positive rate was the highest in gastric cancer group. The positive rate of the CLO test in patients with peptic ulcer and gastric cancer groups was significantly higher than the asymptomatic volunteer group(p0.05). The positive rate of IgG antibody test in the patient group was 82.5% and 45% in the 20 asymptomatic volunteer group. The rate of positivity was the highest in duodenal ulcer group. The positive rate of the serum IgG antibody test in all patient groups was significantly higher than asymptomatic volunteer group(p 0.05). Sensitivity and specificity of CLO test and IgG antibody test in relation to direct H. pylori smear was 94.6%, 76.7%, 96.4%, and 53.47o respectively. Conclusions: The positive rate of the H. pylori infection in patients with peptic ulcer and gastric cancer groups was significantly elevated compared with control and chronic gastritis groups for each of the 3 tests. For clinical purpose, CLO test can be used as a single guide for the treatment of H. pylori infection for its rapidity and efficacy. (Korean J Gastroenterol 1996;28: 19 - 27)
정강민,정현 成均館大學校 科學技術硏究所 1997 論文集 Vol.48 No.1
In this paper, we introduce a new method of replacing multipliers by adders(subtractors). By using the new MNSAO method, we could reduce the number of adders by an average of 1 or 2 per tab compared to the widely used CSD method in reducing the size of the digital filter. Also by replacing multipliers by adders(subtractors) we could reduce the delay time caused by the multiplier. In the current trend of fast and small size digital circuits, the new MNSAO method can provide us a new way of designing small and fast digital filters.