Mixed-mode 시뮬레이션을 이용한 SiC DMOSFETs의 스위칭 특성 분석

강민석,최창용,방욱,김상철,김남균,구상모,Kang, Min-Seok,Choi, Chang-Yong,Bang, Wook,Kim, Sang-Chul,Kim, Nam-Kyun,Koo, Sang-Mo 한국전기전자재료학회 2009 전기전자재료학회논문지 Vol.22 No.9

SiC power device possesses attractive features, such as high breakdown voltage, high-speed switching capability, and high temperature operation. In general, device design has a significant effect on the switching characteristics, In this paper, we demonstrated that the switching performance of DMOSFETs are dependent on the with Channel length ($L_{channel}$) and Current Spreading Layer thickness ($T_{CSL}$) by using 2-D Mixed-mode simulations. The 4H-SiC DMOSFETs with a JFET region designed to block 800 V were optimized for minimum loss by adjusting the parameters of the JFET region, CSL, and epilayer. It is found that improvement of switching speed in 4H-SiC DMOSFETs is essential to reduce the gate-source capacitance and channel resistance. Therefore, accurate modeling of the operating conditions are essential for the optimizatin of superior switching performance.

혈관용해 레이저를 이용한 후두미세수술 최신 지견

강민석,임재열,Kang, Min Seok,Lim, Jae-Yol 대한후두음성언어의학회 2021 대한후두음성언어의학회지 Vol.32 No.2

There are several lasers available for office-based or suspension microlaryngoscopy laser procedures in the treatment of laryngeal diseases. Each has advantages and disadvantages given the depth of penetration per unit of power, absorption in water, spectral absorption characteristics, mode of delivery, safety, and cost. It is important to note that while the proper selection of indication of treatment based on a laser wavelength is critical, of equal importance is selecting the appropriate power setting, focal length (or spot size), and time of exposure. The photoangiolytic lasers precisely target hemoglobin within the microcirculation of the highly vascularized tissue and may have better hemostatic effects and preservation of surrounding normal tissue than the CO₂ laser. Although the choice of laser is purely theoretical and cannot be accurately concluded which parameters of laser (wattage and pulse width) were best to use, photoangiolytic laser surgery is safe and effective for specific laryngeal lesions. In this review, indications for photoangiolytic laser procedures for various laryngeal diseases, laser settings and surgical techniques for specific laryngeal lesions including sulcus vocalis, laryngeal dysplasia, and recurrent respiratory papillomatosis will be introduced. Pros and cons of in-office laser surgery using photoangiolytic laser and flexible CO₂ laser will also be addressed.

SF₆/O₂ 혼합가스에 의한 실리콘 웨이퍼의 표면 텍스쳐링 특성

강민석,주성재,구상모,Kang, Min-Seok,Joo, Sung-Jae,Koo, Sang-Mo 한국전기전자재료학회 2012 전기전자재료학회논문지 Vol.25 No.5

The optical losses associated with the reflectance of incident radiation are among the most important factors limiting the efficiency of a solar cell. Therefore, photovoltaic cells normally require special surface structures or materials, which can reduce reflectance. In this study, nano-scale textured structures with anti-reflection properties were successfully formed on silicon. The surface of sicon wafer was etched by the inductively coupled plasma process using the gaseous mixture of $SF_6+O_2$. We demonstrate that the reflection characteristic has significantly reduced by ~0% compared with the flat surface. As a result, the power efficiency $P_{max}$ of the nano-scale textured silicon solar cell were enhanced up to 20%, which can be ascribed primarily to the improved light trapping in the proposed nano-scale texturing.

4H-SiC DMOSFETs의 계면 전하 밀도에 따른 스위칭 특성 분석

강민석,문경숙,구상모,Kang, Min-Seok,Moon, Kyoung-Sook,Koo, Sang-Mo 한국전기전자재료학회 2010 전기전자재료학회논문지 Vol.23 No.6

SiC power device possesses attractive features, such as high breakdown voltage, high-speed switching capability, and high temperature operation. In general, device design has a significant effect on the switching characteristics. In this work, we report the effect of the interface states ($Q_f$) on the transient characteristics of SiC DMOSFETs. The key design parameters for SiC DMOSFETs have been optimized by using a physics-based two-dimensional (2-D) mixed device and circuit simulator by Silvaco Inc. When the $SiO_2$/SiC interface charge decreases, power losses and switching time also decrease, primarily due to the lowered channel mobilities. High density interface states can result in increased carrier trapping, or more recombination centers or scattering sites. Therefore, the quality of $SiO_2$/SiC interfaces has a important effect on both the static and transient properties of SiC MOSFET devices.

환경경영이 경영성과에 미치는 영향에 관한 연구

강민석,최현석,박병춘,Kang, Min-Seok,Choi, Hyun-Seok,Park, Byung-Chun 한국데이터정보과학회 2011 한국데이터정보과학회지 Vol.22 No.3

본 연구는 공분산 구조방정식 분석기법을 이용하여 환경경영전략, 환경경영시스템, 환경경영활동, 환경경영성과 간의 구조 관계와 상호 영향의 정도를 실증적 자료를 통해 규명하는 데 목적이 있다. 특히 환경경영전략 유형에 따라 이들 요소들 간의 구조 및 영향이 어떻게 달라지는지 규명하는데 연구의 초점을 둔다. 적극형 환경전략유형의 경우 환경경영시스템, 환경경영활동, 환경경영성과 모두에 정 (+)의 유의한 영향을 주었다. 그러나 소극형 환경전략유형의 경우 환경경영시스템, 환경경영활동에는 유의한 영향을 주었으나, 환경경영성과에는 유의한 영향을 미치지 못하였다. This study is to empirically investigate structural relations and the degree of effects among environmental strategy, environmental management system, environmental activities, and firm performance by using structural equation modelling. In particular, we focus on examining how the structure and the effect vary according to the type of environmental strategies. In this study, environmental strategies are classified as "passive type" and "active type" by the cluster analysis, which are used for developing two different research models. For firms employing active environmental strategy, the environmental strategy has a positive effect on all of environmental management system, environmental activities, and firm performance. For firms employing passive environmental strategy, the environmental strategy has a positive effect on both of environmental management system and environmental activities, while it does not have a statistically significant effect on firm performance. The study empirically supports that the active environmental management will result in a positive firm performance.

IEEE 802.160에서 상향링크 VoIP 스케줄링 알고리즘 방식 연구

강민석,장재신,Kang, Min-Seok,Jang, Jae-Shin 한국시뮬레이션학회 2006 한국시뮬레이션학회 논문지 Vol.15 No.3

이동통신이 생활화됨에 따라 유선망에서 사용하고 있는 초고속 인터넷을 무선망에서도 사용하고자 하는 욕구가 증가하게 되었으며 기존 WLAN(Wireless Local Area Network)시스템에서 커버리지 제한 문제와 단말의 이동성을 제공해주지 못하는 단점을 보안하고, 이동통신 시스템에서 고가의 통신요금 문제를 해결하기 위해 WMAN(Wireless Metropolitan Area Network) 표준이 새롭게 등장하였다. IEEE 802.16 계열의 WMAN 표준은 다양한 PHY 계층(SC, SCa, OFDM OFDMA)을 수용할 수 있는 MAC 표준과 단말의 이동성을 지원해주는 MAC 표준을 규정하고 있어서 차기 무선 인터넷에서 중요한 위치를 차지 할 것으로 보인다. 본 논문에서는 VoIP 서비스를 IEEE 802.16d에서 규정하고 있는 4가지 서비스 중 UGS 서비스 형태로 효과적으로 스케줄링 할 수 있는 상향링크 ON/OFF Grant 알고리즘을 제안하고 제안된 알고리즘이 규격에서 정의하는 기존의 방식과 참고문헌의 방식을 이용하여 서비스하는 것보다 VoIP 사용자의 평균 지연시간과 상향링크 자원 활용 측면에서 우수함을 NS-2 시뮬레이션을 통해 제시한다. With the growth of the internet, the number of wireless internet users has increased continuously up to date. However, mobile communications could not support high speed transmission rate with cheap communication fee and wireless LAN has problems in providing terminal mobility and wide area connectivity, respectively. So the WMAN standard has been newly designed to make up for these limits. The initial 802.16 specification effectively offers a solution for providing fixed users with high speed wireless communication but it does not offer terminal mobility. So the 802.16d and 802.16e have been developed as the next generation solution that can support various PHY layer (SC, SCa, OFDM, OFDMA) and offer the terminal mobility. In this paper, we propose an effective uplink scheduling algorithm for VoIP with using UGS, and we show that our proposed algorithm is superior in view of average delay and management of uplink bandwidth to conventional rtPS algorithm and the scheme in reference, with using NS-2 network simulator.

제조 추출물의 혈전 용해 활성에 대한 실험적 연구

강민석,김신,초재승,김효수,김일환,박혜선,서은희,임치혜,Kang, Min-Seok,Kim, Shin,Cho, Jae-Seung,Kim, Hyo-Soo,Kim, Il-Hwan,Park, Hye-Sun,Seo, Eun-Hee,Yim, Chi-Hye 사상체질의학회 2007 사상체질의학회지 Vol.19 No.1

1. Objectives This study was performed to find the activities and characteristics of purified thrombolytic enzymes from Holotrichia extracts. 2. Methods In the first time, a coarse enzyme fluid was made by using the freedried Holotrichia extracts. After manufacturing total soluble proteins and purifing enzymes, it was evauluated the activities and characteristics of this enzyme's dissolving capability to fibrin and thrombus. This study was taken using azocasein assay, fibrin-plate method, native-PAGE and fibrin zymography. 3. Results A soluble proteins were efficiently extracted form freezedried Holotrichia extracts. And, this purified enzyme had a ten times fibrinolytic capability compare with ustulation Holotrichia sample. In native PAGE and fibrin zymography, Holotrichia extracts showed the respectable fibrinolytic activity. Also, It had higher thrombolytic activities compared with general thrombolytic enzyme 'plasmin'. In experiment of various protease inhibitors of the purified enzyme from Holotrichia extracts on the azocaseinolytic activity, the enzyme was strongly inhibited by EDTA ${\cdot}$ EGTA, and weakly by APMSF ${\cdot}$ PMSF ${\cdot}$ TPCK. 4. Conclusion Holotrichia extracts has the thrombolytic activities, and it will operate directly th fibrin-clot and thrombus.

IPA방법에 의한 사이버대학 운영에 대한 중도탈락자의 인식 및 재학생 중도탈락 방지를 위한 개선사항의 우선순의 규명

강민석 ( Min Seok Kang ) 한국교육정보미디어학회(구 한국교육정보방송학회) 2010 교육정보미디어연구 Vol.16 No.4

본 연구는 IPA 방법을 활용하여 사이버대학 중도탈락자가 인식하고 있는 사이버대학 운영에 대한 중도탈락자들의 인식 현황을 파악하고, 중도탈락 방지를 위해 필요한 학교 운영의 개선 사항의 우선순위를 규명하는 것을 목적으로 하였다. 이 연구의 목적을 실현하기 위해 A 사이버대학 총 360명의 학생을 대상으로 전화 설문을 실시하였다. 360명의 자료는 SPSS 12.0 프로그램을 활용하여 분석되었다. 중도탈락자들이 인식하고 있는 중요도와 만족도의 차이를 분석하기 위해 대응표본 t-검정(paired t-test)을 실시하였으며, 중도탈락 방지를 위한 개선 사항을 탐색하기 위해 중요도-만족도 분석(Importance-Performance Analysis: IPA)을 실시하였다. 분석 결과, 사이버대학 운영에 대하여 중도탈락자가 중요하게 생각하고 있는 것에 비해 실제 만족도가 유의미하게 낮은 것으로 나타났다. IPA 를 통해 개선 영역은 지속적 유지영역, 시급 개선 영역, 점진 개선 영역, 잠재적 기회 영역으로 분류되었으며, ‘교수-학습 상호작용’ 영역이 시급 개선 영역으로 나타났다. 아울러 구체적인 개선사항으로 ‘다전공을 위한 학과의 다양성’, ‘온라인 학습자-교수자 상호작용’, ‘오프라인 면대면 상호작용’, ‘학사관련 상담 및 안내의 충실성’, ‘지도교수의 충분한 상담’에 대한 개선이 시급한 것으로 나타났다. 이 연구는 사이버대학 중도탈락자들의 인식 현황을 도출하고, 중도탈락 방지를 위한 개선방안의 우선순위를 실증적으로 도출하였다는 의의가 있다. The purpose of the study is to identify perception of dropout students though Importance-Performance analysis regarding cyber Universities`management, and explore improvement proposals for prevention of dropou using Importance-Performance Analysis(IPA). 360 students in A Cyber University answered the questions on the phone. The data were analyzed by SPSS 12.0. In order to analyze difference between importance and performance which dropout students perceived, paired t-test was conducted. Moreover, to investigate improvement proposals for prevention of dropout, Importance-Performance Analysis(IPA) was conducted. As the result of analysis, performance is significantly lower than Importance which students perceived regarding cyber Universities` management. In addition, domain of improvement is classified as 4 domains - domain of sustaining maintenance, urgent improvement, progressive improvement and potential opportunity. In particular, domain of instruction-learning interaction was included in domain of urgent improvement. Specifically, the following are variables of urgent improvement, various field of study, learner-instructor interaction in online environment, face to face interaction in offline environment, counsel and guide regarding academic affair and consult of advisor. Some further research questions were suggested.

휴대인터넷에서 효과적인 VoIP 스케쥴링 알고리즘 방식 연구

강민석(Min-Seok Kang),장재신(Jaeshin Jang) 한국통신학회 2006 한국통신학회 학술대회논문집 Vol.2006 No.7

사이버대학 e-러닝환경에서 학업성취도에 영향을 미치는 학습 참여 변인 규명

강민석 ( Min-seok Kang ),김진일 ( Jin-il Kim ),박인우 ( Inn-woo Park ) 한국인터넷정보학회 2009 인터넷정보학회논문지 Vol.10 No.5

본 연구의 목적은 사이버대학 e-러닝 환경에서 학업성취도에 영향을 미치는 학습 참여 변인을 규명하는 것이다. 이에 사이버대학 e-러닝 수업에 참여한 학습자를 대상으로, e-러닝 학습 참여 변인과 학업성취도와의 상관관계를 분석하고, 어떤 학습참여 변인이 학업성취도에 영향을 미치는 지, 학습자 배경(성별, 연령별, 학년별)에 따라 학업성취도에 영향을 미치는 학습 참여 변인은 무엇인지를 다중회귀분석을 통해 규명한다. 연구 결과, 학습 참여 변인 중 출석률과 토론게시판 게시 횟수가 학업성취도와 높은 상관관계에 있었으나, 누적학습시간은 상대적으로 낮은 상관관계를 보였다. 학업성취도에 영향을 미치는 학습참여 변인으로는 출석률, 토론 게시판 게시 횟수, 강의실 접속 순으로 규명되었다. 학습자 배경별로는 학업성취도에 영향을 미치는 학습참여 변인간의 차이가 있는 것으로 나타났다. 본 연구결과를 토대로 사이버대학 e-러닝 환경에서 학습자의 학업성취도를 제고하기 위해 학습 참여 변인과 관련하여 고려해야 할 사항을 제언한다. The purpose of this study is to examine the variables related to the students` e-learning participation that have an effect on learning achievement in e-learning environment of cyber universities. Based on the related research, the followings are derive. First, students` attendance and participation in discussion showed higher correlation with the learning achievement than other participation variables. However, the total studying time in online classes showed lower correlation with the learning achievement. Second, the variables that have an effect on the learning achievement were in the order of students` attendance, participation in discussion, access frequency to online classes, learning progress and number of data uploads. Third, by the learners` background, the difference among the variables that have an effect on learning achievement were found. Based on the results above, this study suggests considerations about participation variables to enhance the learning achievement in cyber universities.