표면 도핑 기법을 사용한 SOI RESURF LDMOSFET의 항복전압 및 온-저항 특성 분석

김형우,김상철,방욱,강인호,김기현,김남균,Kim Hyoung-Woo,Kim Sang-Cheol,Bahng Wook,Kang In-Ho,Kim Kl-Hyun,Kim Nam-Kyun 한국전기전자재료학회 2006 전기전자재료학회논문지 Vol.19 No.1

In this paper, breakdown voltage and on-resistance characteristics of the surface doped SOI RESURF LDMOSFET were investigated as a function of surface doping depth. In order to verify the variation of characteristics, two-dimensional device simulation was carried out. Breakdown voltage of the proposed structure is varied from $73 {\~}138V$ while surface doping depth varied from $0.5{\~}2.0{\mu}m$. And on-resistance is decreased from $0.18{\~}0.143{\Omega}/cm^2$ while surface doping depth increased from $0.5 {\~}2.0{\mu}m$. Maximum breakdown voltage of the proposed structure is 138 V at $1.5{\mu}m$ depth of surface doping, yielding $22.1\%$ of improvement of breakdown voltage in comparison with that of the conventional SOI RESURF LDMOSFET with same epi-layer concentration. On-resistance characteristic is also improved about $21.7\%$.

박막증착시 티타늄 표면의 마손저항도와 세포독성에 관한 연구

김형우,김창회,김영수,Kim Hyung-Woo,Kim Chang-Whe,Kim Yung-Soo 대한치과보철학회 2001 대한치과보철학회지 Vol.39 No.1

Titanium is widely used in dentistry for its low density, high strength, fatigue resistance, corrosion resistance, and biocompatibility. But it has a tendency of surface damage under circumstance of friction and impact for its low hardness of the surface. Coating is one of methods fir increasing surface hardness. Its effect is to improve surface physical characteristics without change of titanium. Diamond-like carbon and titanium nitride are known for its high hardness of the surface. So that this study was aimed at the wear test and the cytotoxicity test of the commercially pure titanium and Ti-6Al-4V alloy which were deposited by diamond-like carbon film or titanium nitride film to acertain improvement of the surface hardness and the biocompatibility. A disk (25mm diameter, 2mm thickness) was made of commercially pure titanium and Ti-6Al-4V alloy and these substrates were deposited by diamond-like carbon film or titanium nitride film. Diamond-like carbon film was deposited by the method of radiofrequency plasma assisted chemical vapor deposition and titanium nitride film was deposited by the method of reactive arc ion plating. Then these substrates were tested about wear characteristics by the pin-on-disk type wear tester in which ruby ball was used as a wear causer under the load of 32N, The fracture cycles were measured by rotating the substrates until their films were fractured. The wear volume was measured after 150 cycles and 3,000 cycles using surface profiler. The cytotoxicity test was peformed by the method of the MTT assay. The results were as follows : 1. In the results of the wear volume test, commercially pure titanium and titanium alloy which were coated by diamond-like carbon film or titanium nitride aim had higher resistance against wear than the substrates which were not coated by any films (P<0.05). 2. In the results of the fracture cycle test and the wear volume test, diamond-like carbon film had higher resistance against wear than titanium nitride film (P<0.05). 3. In both coatings of diamond-like carbon aim and titanium nitride film, Ti-6Al-4V alloy had higher resistance against wear than commercially pure titanium (P<0.05) 4. In the results of the cytotoxicity test, diamond-like carbon film and titanium nitride film had little cytotoxicity as like commercially pure titanium or Ti-6Al-4V alloy (P>0.05).

에피층 농도 변화에 따른 Multi-RESURF SOI LDMOSFET의 전기적 특성 분석

김형우,서길수,방욱,김기현,김남균,Kim, Hyoung-Woo,Seo, Kil-Soo,Bahng, Wook,Kim, Ki-Hyun,Kim, Nam-Kyun 한국전기전자재료학회 2006 전기전자재료학회논문지 Vol.19 No.9

In this paper, we analyzed the breakdown voltage and on-resistance of the multi-RESURF SOI LDMOSFET as a function of epi-layer concentration. P-/n-epi layer thickness and doping concentration of the proposed structure are varied from $2{\sim}5{\mu}m\;and\;1\{times}10^{15}/cm^{3}^{\sim}9\{times}10^{15}/cm^{3}$ to find optimum breakdown voltage and on-resistance of the proposed structure. The maximum breakdown voltage of the proposed structure is $224\;V\;at\;R_{on}=0.2{\Omega}-mon^{2}\;with\;P_{epi}=3\{times}10^{15}/cm^{3},\;N_{epi}=7\{times}10^{15}/cm^{3}\;and\;L_{epi}=10{\mu}m$. Characteristics of the device are verified by two-dimensional process simulator ATHENA and device simulator ATLAS.

총의치 환자의 만족도에 대한 연구

김형우,김정희,김영수,Kim, Hyung-Woo,Kim, Chang-Whe,Kim, Yung-Soo 대한치과보철학회 1995 대한치과보철학회지 Vol.33 No.3

A success of complete denture prosthesis can be determined by the satisfaction degree of the dentist and the patient. There are many factors influencing on the satisfaction of the complete denture patients. The purpose of this study is to analyze the correlation between the masticatory satisfaction and clinical evaluation, and the speech satisfaction and clinical evaluation in complete denture patients. 79 patients(total 119 complete dentures) were examined in this study who were treated in Seoul National University Dental Hospital. Through clinical evaluation, 2 examiners evaluated sex, age, edentulous period, the years of having used present complete denture, the number of the previous dentures, the state of the opposite arch, retention, stability, support, occlusion, vertical dimension of the complete denture and the condition of the residual alveolar ridge. Through questionnaires concerned with mastication and speech, examiners evaluate the satisfaction degree of the patients. This study led to the conclusion that : 1. The satisfaction degree of the mastication was lower in older patients(p<0.001) and in patients whose present complete denture period was shorter(p<0.05). The satisfaction degree of the mastication in male was higher than in female patients(p<0.01). 2. The satisfaction degree of the mastication was high when the retention of the complete denture was good(p<0.05), and when the condition of the residual alveolar ridge was good(p<0.05). 3. The satisfacion degree of the speech was high when the retention of the complete denture was good(p<0.01). 4. The satisfaction degree of the mastication was higher in patients with upper and lower complete denture than in patients with single complete denture whose oppsite arch was unilateral partial denture(p<0.05).

시론: 건축학(5년제)과 건축사 자격제도의 정립

김형우,Kim, Hyung-Woo 대한건축사협회 2011 建築士 Vol.2011 No.1

사무소 건축계획의 분석

김형우,Kim, Hyeong-U 대한건축사협회 1980 建築士 Vol.1980 No.1

실리콘 웨이퍼 상에 제작된 미소 유로에서의 유동특성

김형우,원찬식,정시영,허남건,Kim, Hyeong-U,Won, Chan-Sik,Jeong, Si-Yeong,Heo, Nam-Geon 대한기계학회 2001 大韓機械學會論文集B Vol.25 No.12

Recent developments in microfluidic devices based on microelectromechanical systems (MEMS) technique find many practical applications, which include electronic chip cooling devices, power MEMS devices, micro sensors, and bio-medical devices among others. For the design of such micro devices, flows characteristics inside a microchannel have to be clarified which exhibit somewhat different characteristics compared to conventional flows in a macrochannel. In the present study microchannels of various hydraulic diameters are fabricated on a silicon wafer to study the pressure drop characteristics. The effect of abrupt contraction and expansion is also studied. It is found from the results that the friction factor in a straight microchannel is about 15% higher than that in a conventional macrochannel, and the loss coefficients in abrupt expansion and contraction are about 10% higher than that obtained through conventional flow analysis.

희귀 사건 로지스틱 회귀분석을 위한 편의 수정 방법 비교 연구

김형우,고태석,박노욱,이우주,Kim, Hyungwoo,Ko, Taeseok,Park, No-Wook,Lee, Woojoo 한국통계학회 2014 응용통계연구 Vol.27 No.2

본 연구에서는 로지스틱 회귀 모형을 이용하여 보은 지방의 산사태 자료를 분석하였다. 5000 지역의 관측치 가운데 단 9개만이 산사태 발생 지역이므로 이 자료는 희귀 사건 자료로 간주될 수 있다. 로지스틱 회귀 분석 모형이 희귀사건 자료에 적용될 때 주요 이슈는 회귀 계수 추정치에 심각한 편의 문제가 생길 수 있다는 것이다. 기존에 두 가지의 편의 수정 방법이 제안되었는데, 본 논문에서는 시뮬레이션을 통해 정량적으로 비교 연구를 진행하였다. Firth(1993)의 방식이 다른 방법에 비해 우수한 성능을 보였으며, 이항 희귀 사건을 분석하는 데 있어서 매우 안정된 결과를 보여주었다. We analyzed binary landslide data from the Boeun area with logistic regression. Since the number of landslide occurrences is only 9 out of 5000 observations, this can be regarded as a rare event data. The main issue of logistic regression with the rare event data is a serious bias problem in regression coefficient estimates. Two bias correction methods were proposed before and we quantitatively compared them via simulation. Firth (1993)'s approach outperformed and provided the most stable results for analyzing the rare-event binary data.

하악지에서의 하치조신경관 주행에 대한 Conebeam CT를 이용한 연구

김형우,권경환,민승기,오승환,지영덕,고세욱,이재환,온병훈,Kim, Hyong-Woo,Kwon, Kyung-Hwan,Min, Seung-Ki,Oh, Seung-Hwan,Chee, Young-Deok,Koh, Se-Wook,Lee, Jae-Hwan,Ohn, Byung-Hun 대한악안면성형재건외과학회 2009 Maxillofacial Plastic Reconstructive Surgery Vol.31 No.5

Objectives: This study was performed to evaluate course of the inferior alveolar canal in the mandibular ramus and to find safety zone when ramal bone is harvested. Patients and Methods: From January, 2009 to February, 2009, the 20 patients who visited in the Department of Oral and Maxillofacial Surgery, Sanbon Dental Hospital. Wonkwang University and the Conebeam CT was taken of various chief complaints, were selected. The patients who had left and right mandibular first molar and incisor missing, jaw fracture and bone pathology were excluded. The R point was defined as the point which occlusal plane was crossed to the mandibular anterior ramus(external oblique ridge). In the cross-sectional coronal and axial views, the inferior alveolar canal position to the R point, buccal bone width(BW), alveolar crest distance(ACD), distance from alveolar crest to occlusal plane(COD) and inferior alveolar canal to sagittal plane(CS) were measured and horizontal distance(HD), vertical distance(VD) and nearest distance(ND) were measured. Results: The inferior alveolar canal is located $6.19{\pm}1.21\;mm$ from the R point. Horizontal distance from the R point were $13.07{\pm}2.45\;mm$, vertical distance from the R point were $14.24{\pm}2.41\;mm$ and nearest distance from the R point were $10.12{\pm}1.76\;mm$. The course of the inferior alveolar canal was positioned within $0.61{\pm}0.68\;mm$. The distance from external buccal bone to the inferior alveolar canal was increased from the R point anteriorly. Conclusions: It is considered that the mandibular ramus from the R point to 10 mm anteriorly can be harvested safely at ramal bone grafting.

비터비 복호기를 이용한 OFDM-WLAN의 채널등화 및 샘플링 클럭추적

김형우,임채현,한동석,Kim Hyungwoo,Lim Chaehyun,Han Dongseog 대한전자공학회 2005 電子工學會論文誌-TC (Telecommunications) Vol.42 No.5

OFDM(orthogonal frequency division multiplexing) 변조를 이용한 WLAN(wireless local area network) 시스템은 고속 무선 데이터 통신을 위한 대표적 수단으로 전송률의 향상을 위해 활발히 연구되고 있다. 본 논문에서는 WLAN의 정확한 채널 등화와 샘플링 클럭 추적을 위하여 비터비 복호기 출력을 이용한 등화 및 샘플링 클럭 추적 알고리듬을 제안한다. 이 알고리듬은 파일럿 신호를 이용하여 대략의 클럭 주파수 복원과 채널등화를 수행한 후 비터비 복호기의 출력을 다시 부호화하여 등화 및 샘플링 클럭의 추적에 이용하는 알고리듬이다. 제안한 알고리듬의 우수성을 ETSI WLAN 채널 환경에서 컴퓨터 모의실험을 통하여 보였다. IEEE 802.11a is a standard for the high-speed wireless local area network (WLAN), supporting from 6 up to 54 Mbps in a 5 GHz band. We propose a channel equalization algerian and a sampling clock recovery algorithm by utilizing the Viterbi decoder output of the IEEE 802.11a WLAN standard. The proposed channel equalizer adaptively compensates channel variations. The proposed system uses re-encoded Viterbi decoder outputs as reference symbols for the adaptation of the channel equalizer. It also extracts sampling phase information with the Viterbi decoder outputs for fine adjustment of the sampling clock. The proposed sampling clock recovery and equalizer are more robust to noise and frequency selective fading environments than conventional systems using only four pilot samples.