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EDLC와 Backup power controller를 이용한 PLC 데이터 백업 시스템 구현
김석연(Seok-Yeon Kim),남제우(Jae-Woo Nam),강지웅(Ji-Woong Kang) 대한전자공학회 2021 대한전자공학회 학술대회 Vol.2021 No.6
In general, industrial control devices, including PLCs, the data need to be maintained for subsequent work that changes from time to time such as production history or status of production facilities even if when it is turned off. PLC is an equipment that can be programmed according to the user"s needs, and as the industrial environment becomes increasingly complex and high-speed, a situation where a larger amount of data backup is required may occur. Memory for data backup includes Flash-based memory, MRAM, FRAM, etc., which are nonvolatile memory, and battery backup SRAM is also widely used. However, since Flash-based memory takes a long time to read/write data, it is difficult to access it from time to time. In addition, MRAM, FRAM, and SRAM are expensive and occupy a lot of space on the PCB because they have low density compared to memory capacity. To solve this problem, a method was implemented that operation data for backup is in DRAM during operation and transfer it to the Flash-based memory when the power is turned off. After the power is turned off, it is necessary to maintain the power for a period of time to transfer the DRAM data to the flash-based memory. To this end, the EDLC(Electric double layer capacitor) and LTC3351[1], a backup power controller of Analog Device, are used.
한국인에서의 Paraoxonase Gene Polymorphism 과 관동맥 질환과의 관계
유경훈(Kyong Hoon You),김석연(Seok Yeon Kim),김효수(Hyo Soo Kim),손대원(Dae Won Sohn),오병희(Byung Hee Oh),이명묵(Myoung Mook Lee),박영배(Young Bae Park),최윤식(Yun Shik Choi),이영우(Young Woo Lee) 대한내과학회 1998 대한내과학회지 Vol.55 No.6
Objectives: Paraoxonase is a high density lipoprotein (HDL)-associated enzyme, which has been implicated in preventing low density lipoprotein-cholesterol (LDL-C) from oxidation. The human paraoxonase gene is codominantly expressed as allele A and B. The A allele codes for glutamine(A subtype) and the B allele for arginine(B subtype) at codon 192 of the paraoxonase enzyme. This genetic polymorphism divides the enzyme into high and low activity form It has been believed that this difference of specific activity might change the metabolism of cholesterol and the prevalence of coronary artery disease. The present study investigated the association among the paraoxonase gene polymorphism and the level of plasma lipoprotein and coronary artery disease. Methods: The 416 subjects who have undergone coronary angiography in SNUH were recruited. 7he patients(n=251) had >50% stenosis of at least one of the major coronary arteries. To identify the genotype of paraoxonase, we amplified the target region in the paraoxonase gene by PCR(polymerase chain reaction) and electrophoresed the products. Results: There was no difference between the two groups in the allele frequency (A: B = 0.41: 0.59 in patients, A: B = 0.37: 0.63 in controls; p=0.21) or in the genotype frequency (AA:AB:HB= 45:116:90 in patients, AA:AB:BB=22:77:66 in controls; p=0.41). There was no association of the paraoxonase genotype with serum lipoprotein level and acute coronary syndrome in this study. The B allele was not an independent risk factor for coronary artery disease in this study. Conclusion: The paraoxonase gene 192 polymorphism was not an independent risk factor for coronary artery disease in this study.
1 kW급 스털링엔진 고온 열교환기의 Fin 형상 개선 효과 분석
안준(Joon Ahn),김석연(Seok Yeon Kim) 대한기계학회 2017 大韓機械學會論文集B Vol.41 No.8
본 연구에서는 1 kW급 가정용 열병합 시스템의 원동기로 설계된 스털링 엔진의 고온 열교환기에 대하여 Fin 길이, 간격, 각도 등을 조정한 새로운 형상 및 기존 형상에 대하여 수치해석을 수행하여 형상 개선에 따른 성능 향상을 확인하였다. 형상을 개선하는 과정에서 고려하지 않았던 공기예열기를 포함하여 수치해석을 수행한 결과 실린더 헤드 부분에서 음의 열유속이 발생하는 현상이 관찰되었다. 배가스 온도 및 연소실 벽면 온도를 분석하여 이 현상을 규명하였다. 다음으로 이상적인 사이클을 가정하여 형상 개선에 의한 열전달량 증가가 열역학적 사이클 및 시스템 성능에 미치는 영향을 예측하였다. In this research, numerical analysis was carried out on novel and existing fins, adjusted in terms of factors such as length, spacing, and angle, of a high-temperature heat exchanger for a 1 kW class Stirling engine, designed as a prime mover for a domestic cogeneration system. The performance improvement as a result of shape optimization was confirmed with numerical analysis by including the air preheater, which was not considered during optimization. However, a negative heat flux was observed in the cylinder head portion. This phenomenon was clarified by analyzing the exhaust gas and wall surface temperature of the combustion chamber. Furthermore, assuming an ideal cycle, the effects of heat transfer enhancement on the thermodynamic cycle and system performance were predicted.
고콜레스테롤혈증 치료에서 심바스타틴 10mg 과 20mg 사용시의 효능 및 안전성 비교 연구
이재건(Jae Gun Lee),김화민(Hwa Min Kim),이현희(Hyun Hee Lee),최혜진(Hae Jin Choi),박창하(Chang Ha Park),서명덕(Myung Deok Seo),정재천(Jae Cheon Jeong),조한균(Han Kyun Cho),최성식(Sung Sik Choi),이지현(Ji Hyun Lee),김석연(Seok Yeon Ki 대한내과학회 2002 대한내과학회지 Vol.63 No.1
Background: Elevated serum cholesterol level is a major risk factor for cardiovascular morbidity and mortality. Simvastatin is effective for treating hypercholesterolemia. The aim of the study was to evaluate efficacy and safety of 6-month therapy with simvastatin with relatively low dose, 10 mg and 20 mg/day. Methods: One hundred six patients with hyperlipidemia (triglycerides<400 mg/dL and low- density lipoprotein (LDL) cholesterol>130 mg/dL) were randomized to receive either simvastatin 10 mg/day (n=43) or 20 mg/day (n=63). Efficacy was determined by measuring changes from baseline in lipid parameters including LDL cholesterol, total cholesterol, triglycerides and high-density lipoprotein (HDL) cholesterol. Results: Of the one hundred six patients randomized to treatment, forty patients were men and sixty-six patients were women. Fifty-five percent of patients had hypertension, nine percent coronary artery disease and thirteen percent type 2 diabetes mellitus. Mean baseline lipid concentrations were 258 (total cholesterol), 201 (triglycerides), 50 (HDL) and 167 mg/dL (LDL). Both 10 mg and 20 mg of simvastatin produced statistically significant improvements in all measured serum lipid parameters (p<0.001). Compared with 10 mg of simvastatin, 20 mg of simvastatin produced significantly greater (p<0.001) reductions from baseline LDL cholesterol (34.9 mg/dL vs 20.8 mg/dL). But 10 mg of simvastatin was more effective than 20 mg of simvastatin at reducing triglycerides level (42.7 mg/dL vs 22.3 mg/dL). There was no significant difference in both doses at improving total cholesterol and HDL cholesterol level. Percentage of patients at goal LDL as recommended by NCEP guideline (ATP III) were 81% and 80% for patients in low risk but 35% and 50% for patients in coronary heart disease and its risk equivalents, taking 10 mg and 20 mg/day respectively. Both doses were well tolerated. Only 3 patients (4.8%) in the 20 mg group and one patient (2.3%) in the 10 mg group experienced mild adverse events. Most patients contacted by telephone wanted to take 10 mg of simvastatin. Conclusion: In patients with hypercholesterolemia in Korea, both doses (10 mg, 20 mg) of simvastatin were effective in improving serum lipid parameters and well-tolerated. We recommend, considering patients' preference, that 10 mg of simvastatin be intial dosage and in patients with coronary heart disease, higher doses than 20 mg should be prescribed to allow most patients to reach their NCEP target levels.(Korean J Med 63:46-53, 2002)