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4H-SiC Trench MOSFET 응용을 위한Ar Reshape 공정 최적화
성민제,강민재,김홍기,김성준,이정윤,이원범,이남석,신훈규 한국전기전자학회 2018 전기전자학회논문지 Vol.22 No.4
For 4H-SiC trench MOSFET which can reduce on-resistance and switching losses compared to 4H-SiC planar MOSFET,the optimization study for decrease of sub-trench was carried out. In order to decrease sub-trench, Ar reshape process wasused and trench shapes were observed as a function of temperature and process time. As a result, it was confirmed that theprocess conditions for 1500℃ and 20 min were most effective for the suitable trench profiles. In addition, dry/wet oxidationwas performed at the Ar reshaped-samples to observe the oxidation thickness with different crystal orientations. 본 논문에서는 planar MOSFET 대비 on 저항 감소 및 스위칭 속도 개선의 장점이 있는 4H-SiC trench MOSFET응용을위하여 trench MOSFET 중요 이슈 중 하나인 sub-trench의 개선연구를 수행하였다. sub-trench의 제거를 위하여 Arreshape 공정을 수행하였고, 온도와 공정시간을 변화해가며 trench 형태의 변화를 관찰하였다. 그 결과 1500℃, 20분 조건에서 가장 적절한 sub-trench 완화를 확인하였다. 또한 Ar reshape 공정 이후 건식/습식 산화공정을 진행하여 결정방향에 따른산화막 두께변화에 대해 확인하였다
계층적 베이지안 혼합 효과 모델을 사용한 비동차 마코프 체인의 분석
성민제,Sung, Minje 한국통계학회 2014 응용통계연구 Vol.27 No.2
본 연구에서는 비동차 마코프 체인에서 개체들의 전이 행태를 분석하기 위한 계층적 베이지안 방법론을 사용하여 혼합 효과 모델을 소개 하였다. 모델의 모수들에 대한 사후분포가 분석적으로 구해질 수 없는 형태를 가지기 때문에 깁스(Gibbs) 샘플링 시뮬레이션 방법을 사용하여 조건부 사후확률로부터 샘플이 추출되었고, 실제 자료분석을 예를 사용하였다. The present study used a hierarchical Bayesian approach was used to develop a mixed effect model to describe the transitional behavior of subjects in time nonhomogeneous Markov chains. The posterior distributions of model parameters were not in analytically tractable forms; subsequently, a Gibbs sampling method was used to draw samples from full conditional posterior distributions. The proposed model was implemented with real data.
환원된 그래핀 산화물을 보호 층으로 적용한 4H-SiC 표면 거칠기 향상 연구
성민제,김성준,김홍기,강민재,이남석,신훈규 한국전기전자학회 2018 전기전자학회논문지 Vol.22 No.4
We investigated the improvement of surface roughness and states after high temperature annealing usingreduced-graphene oxide (r-GO) capping layer on ion-implanted 4H-SiC epitaxial layer. The specification of the 4H-SiCwafer grown on n-type 4o off-axis 4H-SiC was 10 μm-thick and n-type epitaxial layer with a dose of 1.73 × 1015 cm-2. The n+ region were formed by multiple nitrogen ion-implantations and r-GO capping layer was produced by spraycoating method. AFM measurements revealed that RMS value of the sample capped with r-GO was tenfold decreasecompared to the sample without r-GO capping. The improvement of surface states was also verified by the improvementof leakage current level. 본 연구에서는 이온주입 된 4H-탄화규소(SiC) 에피 층 위에 환원된 그래핀 산화물 (r-GO)을 보호 층으로 적용하여 고온열처리 공정 중 발생하는 표면 거칠기 악화를 개선하였다. 실험에 사용 된 4H-SiC 에피 층은 4° off-axis n-형 4H-SiC 기판위에 10 μm 두께로 성장되었다. n+-형 4H-SiC 층을 제공하기 위해 1.73 × 1015 cm-2 농도의 질소를 고온·고에너지 이온주입공정으로 주입하였고, 보호 층으로 사용한 r-GO는 스프레이 코팅 방식으로 4H-SiC 층 위에 형성하였다. r-GO를 보호 층으로 적용 한 결과, 적용하지 않은 시료에 비해 고온 열처리 후 표면 거칠기 (RMS)가 10배 개선되었으며, 전기적 측정으로 추출한 누설 전류를 통해 표면 거칠기 개선으로 표면 상태가 완화되었음을 확인하였다
성민제,Tae Seop Lim,Mi Young Jeon,Hye Won Lee,Beom Kyung Kim,Do Young Kim,Sang Hoon Ahn,Kwang-Hyub Han,Jun Yong Park,Seung Up Kim 거트앤리버 소화기연관학회협의회 2020 Gut and Liver Vol.14 No.5
Background/Aims: Sarcopenia is associated with liver fibrosis in patients with nonalcoholic fatty liver disease and chronic hepatitis B. We investigated the association between sarcopenia and hepatic fibrotic burden in patients with type 2 diabetes mellitus (T2DM). Methods: Patients with T2DM who had received a comprehensive medical health checkup were recruited. Muscle mass was assessed using computed tomography. Fibrotic burden was assessed using the fibrosis-4 index (FIB-4). The study population was divided by quartile stratification of the lumbar skeletal muscle index (LSMI). Results: Among 309 patients with T2DM, 75 (24.3%) had sarcopenia. These patients were significantly older and had higher FIB-4, whereas they had significantly lower body mass index (BMI) and LSMI than patients without sarcopenia (all p<0.05). The LSMI showed a significant negative correlation with the FIB-4 when analyzed in terms of quartile stratification (p=0.003). Multivariate analysis showed that female sex and higher BMI were independently associated with a reduced risk of sarcopenia (odds ratio [OR], 0.388; 95% confidence interval [CI], 0.199 to 0.755 and OR, 0.704; 95% CI, 0.618 to 0.801; all p<0.05), whereas a higher FIB- 4 was independently associated with an increased risk of sarcopenia (OR, 1.817; 95% CI, 1.180 to 2.797; p=0.007). Among patients with a BMI <25 kg/m2 (n=165), those with sarcopenia (n=54, 32.7%) had a significantly higher FIB-4 than those without (n=111, 67.3%; 1.66 vs 1.38, p=0.004). Conclusions: Sarcopenia is independently associated with fibrotic burden in patients with T2DM. Further studies should investigate whether the improvement of sarcopenia can ameliorate liver fibrosis in patients with T2DM.
성민제 한국경영과학회 2006 Management Science and Financial Engineering Vol.12 No.2
We use the hierarchical Bayesian approach to describe the transition probabilities of a binary non-homogeneous Markov chain. The Markov chain is used for describing the transition behavior of emotionally disturbed children in a treatment program. The effects of covariates on transition probabilities are assessed using a logit link function. To describe the time evolution of transition probabilities, we consider two modeling strategies. The first strategy is based on the concept of exchangeability, whereas the second one is based on a first order Markov property. The deviance information criterion (DIC) measure is used to compare models with two different time dependent structures. The inferences are made using the Markov chain Monte Carlo technique. The developed methodology is applied to some real data.
성민제,조성빈 한국경영과학회 2006 Management Science and Financial Engineering Vol.12 No.1
This study proposes a Bayesian dynamic model in a hierarchical way to assess the time-varying effect of risk factors on the likelihood of corporate bankruptcy. For the longitudinal data, we aim to describe dynamically evolving effects of covariates more articulately compared to the Generalized Estimating Equation approach. In the analysis, it is shown that the proposed model outperforms in terms of sensitivity and specificity. Besides, the usefulness of this study can be found from the flexibility in describing the dependence structure among time specific parameters and suitability for assessing the time effect of risk factors.
성민제 대한소화기암연구학회 2023 Journal of Digestive Cancer Research (JDCR) Vol.11 No.3
Pancreatic cancer is one of the most aggressive cancers, and it is expected to become the second-leading cause of cancer-related death in the United States by 2030. Its 5-year survival rate is <10% and approximately 15% of cases are eligible for surgical treatment during diagnosis. Furthermore, the risk of recurrence within 1 year postoperative is as high as 50%. Therefore, chemotherapy plays a crucial role in pancreatic cancer treatment. Survival rates are speculated to have improved since the introduction of FOLFIRINOX and gemcitabine/nab-paclitaxel combination therapy for metastatic pancreatic cancer in the 2010s. Additionally, the implementation of both neoadjuvant and adjuvant treatments in resectable and borderline resectable pancreatic cancer caused better outcomes compared to upfront surgery. Recently, not only have these medications advanced in development, but so have PARP inhibitors and KRAS inhibitors, contributing to the treatment landscape. This study aimed to explore the latest insights into chemotherapy for pancreatic cancer.