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See-saw Type RF MEMS Switch with Narrow Gap Vertical Comb
Sungchan Kang,Sungsoo Moon,Hyeon Cheol Kim,Kukjin Chun 대한전자공학회 2007 Journal of semiconductor technology and science Vol.7 No.3
This paper presents the see-saw type RF MEMS switch based on a single crystalline silicon structure with narrow gap vertical comb. Low actuation voltage and high isolation are key features to be solved in electrostatic RF MEMS switch design. Since these parameters in conventional parallel plate RF MEMS switch designs are in trade-off relationship, both requirements cannot be met simultaneously. In the vertical comb design, however, the actuation voltage is independent of the vertical separation distance between the contact electrodes. Therefore, the large separation gap between contact electrodes is implemented to achieve high isolation. We have designed and fabricated RF MEMS switch which has 46dB isolation at 5㎓, 0.9㏈ insertion loss at 5㎓ and 40V actuation voltage.
Comb drive를 이용한 SPDT RF MEMS 스위치에 관한 연구
강성찬(Sungchan Kang),김현철(Hyeon Cheol Kim),전국진(Kukjin Chun) 대한전자공학회 2007 대한전자공학회 학술대회 Vol.2007 No.11
This paper present a single pole double throw (SPDT) RF MEMS switch with fine gap combs. We fabricated SPDT RF MEMS switch using fine gap combs on single crystal silicon to improve RF characteristic and reliability. As a result, fabricated switch showed insertion loss less than 0.26 ㏈, return loss greater than 25 ㏈, isolation greater than 39㏈ at 6㎓, and low actuation voltage at 15V.
Comb drive를 이용한 RF MEMS 스위치에 관한 연구
강성찬(Sungchan Kang),김현철(Hyeon Cheol Kim),전국진(Kukjin Chun) 대한전자공학회 2008 電子工學會論文誌-SD (Semiconductor and devices) Vol.45 No.4
본 논문에서는 comb drive를 이용하여 수평 방향 저항 접촉 방식의 RF MEMS 스위치 개발을 소개한다. 무선통신 트랜시버에서 사용되는 FEM에서 사용될 수 있는 높은 안전성과 좋은 RF 특성을 가지는 스위치의 개발을 목표로 한다. 따라서 작은 삽입손실 특성을 가지기 위해 comb drive를 이용하여 큰 접촉 힘을 발생시키고, 큰 격리도 특성을 가지기 위해 스위치 off 상태에서 작은 정전용량을 갖도록 한다. 그리고 단결정 실리콘을 스위치의 구조물로 사용함으로써 기계적인 안전성을 갖도록 한다. 개발된 RF MEMS 스위치는 26 V의 동작 전압을 가지며, 2 ㎓에서 0.44 ㏈ 이하의 삽입손실과 60 ㏈ 이상의 격리도 특성을 가진다. This paper presents a lateral resistive contact RF MEMS switch using comb drive. Our goal was to fabricate the RF MEMS switch with high reliability and good RF characteristics for front end module in wireless transceiver system. Therefore, comb drive is used for large contact force in order to achieve low insertion loss and small off-state capacitance in order to achieve high isolation. The single crystalline silicon is used for mechanical reliability. As a result, the developed switch showed insertion loss less than 0.44 ㏈ at 2 ㎓, isolation greater than 60 ㏈, and low actuation voltage at 26 V.
Eun Jee Chang,Sanggu Kang,Sungchan Kang,Su Jin Kang 대한예방의학회 2023 예방의학회지 Vol.56 No.1
Objectives: Previous studies have reported that people with disabilities are more likely to be impoverished and affected by excessive medical costs than people without disabilities. Public transfer income (PTI) reduces financial strain in low-income households. This study examined the impact of PTI on catastrophic health expenditures (CHE), focusing on low-income households and households with Medical Aid beneficiaries that contained people with disabilities. Methods: We constructed a panel dataset by extracting data on registered households with disabilities from the Korea Welfare Panel Study 2012-2019. We then used a generalized estimating equation model to estimate the impacts of PTI on CHE. A subgroup analysis was carried out to assess the moderating effects of family income levels and health insurance types. Results: As PTI increased, the odds ratio (OR) of CHE in households that contained people with disabilities decreased significantly (OR, 0.92; 95% confidence interval [CI], 0.89 to 0.94; p<0.001). In particular, PTI effectively reduced the likelihood of CHE for low-income households (OR, 0.85; 95% CI, 0.81 to 0.89; p<0.001) and those who received medical benefits (OR, 0.78; 95% CI, 0.68 to 0.89; p<0.001). Conclusions: This study highlights the positive effect of PTI on decreasing CHE. Household income and the health insurance type were significant effect modifiers, but economic barriers seemed to persist among low-income households with non-Medical Aid beneficiaries. Federal policies or programs should consider increasing the total amount of PTI targeting low-income households with disabilities that are not covered by the Medical Aid program.
증발하는 물방울의 계면활성제에 의한 열모세관 유동 억제
윤성찬(Sungchan Yun),김태권(Tae Kwon Kim),임희창(Hee Chang Lim),강관형(Kwan Hyoung Kang),임근배(Geunbae Lim) 대한기계학회 2013 大韓機械學會論文集B Vol.37 No.7
본 논문은 비이온의 계면 활성제에 의해 증발하는 물방울의 열모세관 유동(마랑고니 유동)이 억제되는 것을 실험적으로 검증한다. 물방울이 소수성 표면 위에서 증발할 때, 액적 내부의 마랑고니 유동을 관찰하였고, 계면 활성제 농도에 따라 이 유동이 억제되는 것을 조사하였다. 초기 계면 활성제 농도가 증가하면, 마랑고니 유동의 속도와 수명이 감소한다. 이 결과는 계면 활성제에 의해 액적계면에서 점착 경계 조건이 성립됨을 보여주는데, 이것은 계면 점착 현상과 관련된 기존의 모델에 기초하여 설명되었다. 또한 액적의 초기 계면 활성제 농도가 임계 농도 이하일 때, 증발 초기 접촉선 비고정 현상을 발견했는데, 이것은 마랑고니 유동이 접촉각의 이력 현상을 감소시키기 때문이다. The suppression of a thermocapillary flow (Marangoni flow) by a nonionic surfactant is experimentally investigated for evaporating pure water droplets on hydrophobic substrates. The experiment shows that as the initial concentration of the surfactant increases, the velocity and lifetime of the flow monotonically decrease. The result confirms the no-slip boundary condition at a liquid-air interface, which is explained on the basis of the previous model regarding the effect of surfactants on the no-slip condition. Interestingly, at an initial concentration much less than a critical value, it is found that depinning of the contact line occurs during the early stage of evaporation, which is ascribed to a reduction in the contact angle hysteresis owing to the presence of the Marangoni flow.
그래프 모델과 중심성 분석을 이용한 당뇨환자의 처방 및 검사결과의 상관관계 분석
유강민(Kang Min Yoo),박성찬(Sungchan Park),이수진(Su-jin Rhee),유경상(Kyung-Sang Yu),이상구(Sang-goo Lee) 한국정보과학회 2015 정보과학회 컴퓨팅의 실제 논문지 Vol.21 No.7
본 논문은 11,938명의 당뇨환자 의료데이터를 그래프 모델로 변환하고 중심성 분석 기법으로 처방과 검사결과 간 상관관계를 추출해내는 과정에 대해 다루고 있다. 관계형 데이터베이스로 저장되어있는 데이터를 RDB2Graph 프레임워크를 사용하여 유의미한 그래프로 변환하였다, 변환된 그래프에 Personalized PageRank를 적용하여 처방과 검사 간 상관관계를 분석했다. 사용된 그래프 모델에는 환자 별 의료기록 모델과 의료 기록의 시간적 간격을 고려한 모델이 있다. 분석 결과 기존의 의학적 지식에 부합하는 상관관계를 다수 발견할 수 있었으며, 본 논문에서는 발견한 상관관계 중 주요 사례를 소개하여 본 분석방법의 유효함을 보인다. This paper presents the results and the process of extracting correlations between events of prescriptions and examinations using graph-modeling and node centrality measures on a medical dataset of 11,938 patients with diabetes mellitus. As the data is stored in relational form, RDB2Graph framework was used to construct effective graph models from the data. Personalized PageRank was applied to analyze correlation between prescriptions and examinations of the patients. Two graph models were constructed: one that models medical events by each patient and another that considers the time gap between medical events. The results of the correlation analysis confirm current medical knowledge. The paper demonstrates some of the note-worthy findings to show the effectiveness of the method used in the current analysis.
마이크로 채널에서의 기울어진 그루브 주변의 작은 레이놀즈 수 유동 패턴 : 그루브 깊이 효과와 효율적인 슬립 모델의 유효성
윤성찬(Sungchan Yun),강관형(Kwan Hyoung Kang) 한국가시화정보학회 2010 한국가시화정보학회 학술발표대회 논문집 Vol.2010 No.11
A pressure driven flow over grooves generates a transverse velocity component to the principal direction of flow. For simplicity of analysis, an effective slip velocity is applied to represent the transverse velocity developed by slanted grooves. However, since the slip model is based on a periodically placed infinite length of linear grooves, the validity of model is limited. In this work, we investigated flow patterns over grooves numerically, and the results are verified experimentally. Based on the numerical results, we determined the range of depth and width of the grooves in which the effective slip model can be applied.
Electrorefining Characteristics of Uranium by Using a Graphite Cathode
Youngho Kang,JongHyeon Lee,Sungchan Hwang,JoonBo Shim,EungHo Kim 한국방사성폐기물학회 2007 방사성폐기물학회지 Vol.5 No.1
흑연음극을 이용하여 LiCl-KCl공융염내에서 금속우라늄의 전해정련을 수행하였다. Uraniurn-Graphite Intercalation Compound(U-GIC)의 형성에 의하여 우라늄 전착물의 sell-scraping이 일어나며 전해정련에서 stripping과정을 생략함으로서 전해효율을 높일 수 있다. 우라늄 전착물내의 희토류 원소 오염은 무시할 만 하였으나 약 300ppm정도의 탄소가 오염되어 있는 것으로 관찰되었다. 탄소 오염은 이트륨을 이용한 정제공정 등을 거칠 경우 제거 가능하리라 사료된다. 회수된 우라늄 전착물의 조직 특성을 분석하였으며, 스틸 음극에 의해 회수된 전착물과 비교하였다. 이 결과는 초기 실험결과 이며 보다 심층적 연구를 통하여 사용 후 금속핵연료의 전해정련 개념을 개선시킬 수 있을 것으로 판단된다. Electrorefining experiments were successfully carried out in LiCl-KCl eutectic molten salt with a graphite cathode. It was found that the formation of Uranium-Graphite intercalation compound(U-GIC) helped the self-scraping mechanism of the uranium dendrite and the efficiency of the electrorefiner increased due to an elimination of the stripping step. The contaminations of the uranium deposit by rare earth elements was negligible while about 300 ppm of carbon was observed. The carbon contamination is believed to be eliminated by further purification by yttrium reaction. The morphology characteristics of the recovered U deposit was compared to that of steel cathode. These are only qualitative preliminary experimental results, but we believe that further research on this type of activity change the direction of the electrorefining research on spent nuclear fuel.