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2P-24 Analysis of surface wrinkling on multiple stacked metal/polymeric layer via free energy
유성수,유필진 한국공업화학회 2017 한국공업화학회 연구논문 초록집 Vol.2017 No.1
Surface wrinkling can be occurred when compressive stress in the film exceeds the critical stress, and there have been a number of researches on instability of wrinkling. Since most of electronic devices in nanoscale possess sequentially stacked layer structure, instability of surface wrinkling on multilayer can be significant tool for fabrication of electronic device. However, most of researches focus on wrinkling on bilayer, not for the wrinkling on multilayer. Therefore, instability of wrinkling on multilayer has been less investigated. In this research, we designed models for free energy analysis that can analyze multilayer wrinkling, and derived relationship between measurable parameter such as wavelength of wrinkled surface, elastic modulus, poisson’s ratio and thickness. In addition we introduced metrology that can overcome the limitation of conventional metrology based on bilayer wrinkling s application of this instability of multilayer wrinkling.
Frequency Stability Enhancement of Power System using BESS
유성수,곽은섭,문채주 한국전자통신학회 2022 한국전자통신학회 논문지 Vol.17 No.4
Korea has the characteristics of traditional power system such as large-scale power generation and large-scale power transmission systems, including 20 GW large-scale power generation complexes in several regions with unit generator capacity exceeding 1.4 GW, 2−3 ultra-high-voltage transmission lines that transport power from large-scale power generation complexes, and 6 ultra-high-voltage transmission lines that transport power from non-metropolitan areas to the metropolitan area. Due to the characteristics of the power system, the penetration level for renewable energy is low, but due to frequency stability issue, some generators are reducing the output of generators. In the future, the issue of maintaining the stability of the power system is expected to emerge as the most important issue in accordance with the policy of expanding renewable energy. When non-inertial inverter-based renewable energy, such as solar and wind power, surges rapidly, the means to improve the power system stability in an independent system is to install a natural inertial resource synchronous condenser (SC) and a virtual inertial resource BESS in the system. In this study, we analyzed the effect of renewable energy on power system stability and the BESS effect to maintain the minimum frequency through a power system simulation. It was confirmed that the BESS effect according to the power generation constraint capacity reached a maximum of 122.81%. BESS is very slow in response time compared to natural inertia, so it is very important to operate the BESS combined with the synchronous condenser as a controller for improving transient stability.
유성수,권현희,박경찬,윤현대,이지현,손호상 대한당뇨병학회 2002 임상당뇨병 Vol.3 No.3
저자들은 전신 쇠약감을 주소로 내원 한 환자에서 흑색극세포증과 당뇨병성 케톤산혈증이 동반된 1예를 경험하였기에 이를 문헌 고찰과 함께 보고한다. Acanthosis nigricans is a skin lesion characterized by localized areas of brown hyperpigmented and velvety hyperplastic skin. Typically, it is found at body folds such as the neck and axilla. This condition is frequently accompanied by insulin resistance, hyperinsulinemia and obesity or it may be a signal of underlying malignant disorder, such as gastric cancer. Although diabetic ketoacidosis may develop in patients with type 2 diabetes when they experience severe metabolic stress, it usually occurs only in individuals whose circulating insulin is virtually absent. Because acanthosis nigricans is seen in insulin-resistant states or hyperinsulinemic states, patients with acanthosis nigricans are not likely to develop diabetic ketoacidosis. Because of the unexpected occurrence of diabetic ketoacidosis in association with acanthosis nigricans, we report this case.
유성수,김은영,천종운,서창진,조자경,하형근,정진태,권중구,이창형,김호각 대한소화기내시경학회 2005 Clinical Endoscopy Vol.30 No.5
Background/Aims: Endoscopic retrograde cholangiopancreatography (ERCP) is the gold standard for diagnosis and treatment of common bile duct stones (CBDS). However it is associated with some complications. Endoscopic ultrasonography (EUS) is an efficient diagnostic tool for CBDS with better accuracy than ultrasonography (USG) or computed tomography (CT) and lower complication rate than ERCP. We evaluated the diagnostic usefulness of EUS in suspicious CBDS. Methods: From Oct. 2001 to Mar. 2004, 84 patients with the suspicion of CBDS, without definite evidence on CT and/or USG were evaluated with EUS. The reports were reviewed retrospectively. Results: Patients were 38 males, 46 females with mean age of 56 years old. CBDS were found in 25 (29.8%) patients. In the diagnosis of CBDS undetected in CT and/or USG, EUS gave 96% sensitivity, 96.6% specificity, 92.3% positive predictive value and 98.3% negative predictive value. When CBDS were found in EUS, the average sizes of CBD and CBDS were 8.8 mm (4∼16.7) and 6.4 mm (3.3∼9.1) respectively. Diagnostic ERCP was avoided in 54 (64.3%). EUS provided additional diagnosis such as gallbladder stones, gallbladder cancer, ampullary cancer and adenoma. No complication was associated with EUS. Conclusions: EUS is reasonably safe and accurate procedure in detecting CBDS. EUS may possibly replace diagnostic ERCP in CBDS. 목적: 총담관결석의 진단에 있어서 내시경적역행성담췌관조영술(endoscopic retrograde cholangiopancreatography, ERCP)은 높은 정확도를 보이며 치료적 시술을 병행할 수 있는 장점이 있지만, 침습적인 시술로 합병증이 동반될 수 있고 시술이 실패할 수도 있다. 내시경초음파검사(endoscopic ultrasonography, EUS)는 총담관결석의 진단에 복부초음파검사(abdominal ultrasonography, USG)나 복부전산화단층촬영(abdominal computed tomography, CT)보다 높은 정확도를 보이고, ERCP보다 덜 침습적이며 합병증이 적다. 본 연구는 총담관결석이 의심되는 환자에서 EUS의 유용성을 알아보고자 하였다. 대상 및 방법: 2001년 10월부터 2004년 3월까지 대구가톨릭대학병원에서 총담관결석이 의심되어 USG나 CT를 실시하였으나 총담관결석 유무를 정확히 확인할 수 없어서, EUS가 추가적으로 실시되었던 84명의 환자를 대상으로 후향적 조사를 실시하였다. 결과: 대상환자는 남자 38명, 여자 46명, 평균 연령 56세(22~81)였다. 그 중 25명(29.8%)에서 총담관결석이 진단되었다. USG나 CT에 보이지 않는 총담관결석의 진단에서 EUS는 민감도 96%, 특이도 96.6%, 양성예측도 92.3%, 음성예측도 98.3%를 보였다. 총담관결석이 보인 경우, EUS로 측정한 총담관의 평균크기는 8.8 mm (4~16.7), 총담관결석의 평균크기는 6.4 mm (3.3~9.1)였다. EUS로 진단적 ERCP를 피할 수 있었던 경우는 54예(64.3%)였다. 또한 EUS로 담낭결석, 담낭암, 팽대부선종, 팽대부암 등의 추가진단을 얻을 수 있었다. 전 예에서 시술과 관련된 합병증은 없었다. 결론: 총담관결석의 진단에 EUS는 높은 정확도를 보이는 안전하고 유용한 검사이며, 진단적 ERCP를 대체할 수 있을 것으로 생각한다.