• 대한전기학회논문지:전력기술부문A
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• 제48권5호
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• pp.622-628
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• 1999

This paper presented to design a robust turbo-generator control system using {{{{ { H}_{$\infty$ } }}}} control synthesis for improving small-signal stability. Application study of{{{{ { H}_{$\infty$ } }}}} control synthesis is more appropriate in this system since a turbo-generator system is usually operated under circumstance of unmeasurable modelling uncertainty and external disturbance. The{{{{ { H}_{$\infty$ } }}}} control theory was briefly reviewed for good understanding and the reasonable approach. The design results are simulated for a case study and to check the system performance in comparison with currently operating Lead/Lag filtered PSS performance.

• 대한전기학회논문지:시스템및제어부문D
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• 제50권10호
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• pp.464-472
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• 2001

This study uses distributed parameter systems as the spatial discretization technique, modelling in lumped parameter systems, and applies fast WALSH transform and the Picard's iteration method to high order partial differential equations and matrix partial differential equations. This thesis presents a new algorithm which usefully exercises the optimal control in the distributed parameter systems. In exercising optimal control of distributed parameter systems, excellent consequences are found without using the existing decentralized control or hierarchical control method. This study will help apply to linear time-varying systems and non-linear systems. Further research on algorithm will be required to solve the problems of convergence in case of numerous applicable intervals.

• 조명전기설비학회논문지
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• 제16권3호
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• pp.101-109
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• 2002

원자력발전소 제어계통중 운전 정지에 많은 영향을 주고 제어하기 가장 까다로운 중기발생기 수위 제어는 특히 기동시 및 저 출력시에 자동제어는 물론 수동제어도 매우 어려운 상태이다. 중기발생시 수위특성을 분석하여 안정성이 보장된 증기발생기 수위 제어 계통의 제어방법을 개선하여 제어 성능과 신뢰도를 향상시킬 수 있는 알고리즘을 개발하고 디지털 제어 시스템으로 구현하여 실제 발전소에 설치 적용하였다.

• 한국건축시공학회지
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• 제5권4호
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• pp.153-164
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• 2005

This study aims at establishing JIT production management system to enable manage the resources input into from procurement through construction based on correct identification of the process, an analysis on the amount of input materials and information sharing. This study has focused on the process control and working process of rebar work in domestic apartment house construction where the overall scope of Process from the planning phase to the construction phase has been analyzed in this study. Also construction phase was selected for the application of a sample case. A basic model for JIT production was generated with these processes. Furthermore A questionnaire and the on-site survey with process, checklist and control data were prepared and performed for the application of JIT production management model into rebar work. The governing scopes of JIT production management system include process management, material management, yard loading and moving management and inventory control, and the operation of each control item

• 대한기계학회논문집B
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• 제21권2호
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• pp.316-328
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• 1997

There were appreciable progresses on the study of shock wave / boundary layer interaction control in the transonic flow without nonequilibrium condensation. But in general, the actual flows associated with those of the airfoil of high speed flight body, the cascade of steam turbine and so on accompany the nonequilibrium condensation, and under a certain circumstance condensation shock wave occurs. Condensation shock wave / boundary layer interaction control is quite different from that of case without condensation, because the droplets generated by the result of nonequilibrium condensation may clog the holes of the porous wall for passive control and the flow interaction mechanism between the droplets and the porous system is concerned in the flow with nonequilibrium condensation. In these connections, it is necessary to study the condensation shock wave / boundary layer interaction control by passive cavity in the flow accompanying nonequilibrium condensation with condensation shock wave. In the present study, experiments were made on a roof mounted half circular arc in an indraft type supersonic wind tunnel to evaluate the effects of the porosity, the porous wall area and the depth of cavity on the pressure distribution around condensation shock wave. It was found that the porosity of 12% which was larger than the case of without nonequilibrium condensation produced the largest reduction of pressure fluctuations in the vicinity of condensation shock wave. The results also showed that wider porous area, deeper cavity for the same porosity of 12% are more favourable "passive" effect than the cases of its opposite. opposite.

• Journal of Preventive Medicine and Public Health
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• 제36권1호
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• pp.47-53
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• 2003

Objectives : I used a case-crossover design to investigate the association between air pollution, and hospital admissions for asthmatic children under the age of 15 years in Seoul, Korea Methods : I estimated the changes in the levels of hospitalization risk from theinterquartile (IQR) increase in each pollutant concentrations, using conditional logistic regression analyses, with controls for weather information. Results : Using bidirectional control sampling, the results from a conditional logistic regression model, with controls for weather conditions, showed the estimated relative risk of hospitalization for asthma among children to be 1.04 (95% confidence interval (CI), 1.01-1.08) for particulate matter with an aerodynamic diameter less than or equal to 10m (IQR=40.4ug/m3); 1.05 (95% CI, 1.00- 1.09) for nitrogen dioxide (IQR=14.6ppb): 1.02 (95% CI,0.97-1.06) for sulfur dioxide (IQR=4.4ppb): 1.03 (95% CI, 0.99-1.08) for ozone (IQR=21.7ppb): and 1.03 (95% CI, 0.99-1.08) for carbon monoxide f10R=1.0ppm). Conclusions : This empirical analysis indicates the bidirectional control sampling methods, by design, would successfully control the confounding factors due to the long-term time trends of air pollution. These findings also support the hypothesis that air pollution at levels below the current ambient air quality standards of Korea is harmful to sensitive subjects, such as asthmatic children.

• Journal of Nutrition and Health
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• 제36권6호
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• pp.613-621
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• 2003

The purpose of this study was to investigate the association between dietary quality and the risk of coronary heart disease (CBD) among Korean men by a case-control study. Methods: The cases were 108 male patients with a first acute myocardial infarction or a new diagnosis of angina pectoris who were admitted to a university teaching hospital in Seoul. Controls were 142 age-matched patients admitted to the departments of ophthalmology and orthopedic surgery at the same hospital. Dietary information was assessed by a nutritionist using a semiquantitative food frequency questionnaire (FFQ), and dietary quality index (DQI) scores were calculated. Results: The intakes of total fat and cholesterol and body mass index (BMI) in cases were significantly higher than those in controls. The mean DQI scores were 8.6 for the cases and 9.4 for the controls. A higher DQI, which was indicative of a better quality diet, was inversely associated with the risk of CHD when comparing the highest to lowest quatiles, but borderline significant (odd ratios 0.60, 95% confidence interval 0.25-1.39, P for trend ＝ 0.05). Conclusions: Our findings suggest that better dietary quality may reduce the risk of CHD among Korean men.

• Asian Pacific Journal of Cancer Prevention
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• 제16권6호
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• pp.2347-2350
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• 2015

Childhood acute lymphoblastic leukemia (ALL) is one of the most common hematologic malignancies, accounting for one fourth of all childhood cancer cases. Exposure to environmental factors around the time of conception or pregnancy can increase the risk of ALL in the offspring.This study aimed to evaluted the role of prenatal and postnatal exposure to high voltage power lines on the incidence of childhood ALL.This cross-sectional case control study was carried out on 22 cases and 100 controls who were born and lived in low socioeconomic families in Isfahan and hospitalized for therapeutic purposes in different hospitals from 2013-2014.With regard to the underlying risk factors, familial history and parental factors were noted but in this age, socioeonomic and zonal matched case control study, prenatal and childhood exposure to high voltage power lines was considered as the most important environmental risk factors of ALL (p=0.006, OR=3.651, CI 95%, 1.692-7.878). As the population was of low socioeconomic background, use of mobiles, computers and microwave was negligible. Moreover prenatal and postnatal exposure to indoor electrically charged objects was not determined to be a significant environmental factor. Thus, pre and post natal exposure to high voltage power lines and living in pollutant regions as well as familial influence could be described as risk factors of ALL for the first time in a low socioeconomic status Iranian population.

• 응용통계연구
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• 제18권2호
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• pp.297-310
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• 2005

본 연구에서는 강화연구(서일, 2004)를 통해 수집된 277명의 환자-대조군 자료와 40개의 가계 자료를 이용하여 ACE(angiotensin-I converting enzyme) 유전자 내에 있는 4개의 단일염기다형성(single nucleotide polymorphism; SNP)으로 이루어진 일배체형(haplotype)과 고혈압의 관련성을 알아보고자 한다. 이를 위해 일배체형에 기초한 환자-대조군의 우도비 검정과 가계 자료의 TDT(transmission/disequilibrium test) 연구를 수행하고자 한다. 또한 이 일배체형을 동정(identification)할 수 있는 tag-SNPs에 기초하여 동일한 연구를 하고자 하며, Seltman 등(2003)이 제안한 분기도(cladogram) 분석 방법을 써서 일배체형의 진화 과정에서 가깝게 위치하고 질병 발생 위험이 비슷한 클레이드(clade)를 찾아내고 이 클레이드와 고혈압의 연관성을 살펴보고자 한다.

• Asian Pacific Journal of Cancer Prevention
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• 제16권9호
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• pp.3685-3690
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• 2015

Background: Low-dose oral contraceptives (OC) were approved by the Japanese Ministry of Health, Labor and Welfare in 1999, yet despite their contraceptive and non-contraceptive health benefits, only 5% of the target population use them. Fear of increased cancer risk, particularly breast cancer, is one reason for this. Due to low OC uptake and low screening participation, a paucity of data is available on the risk of OC use and breast cancer in Japanese women. The present study investigated OC use and breast cancer risk, as well as menstrual, reproductive and family factors. Materials and Methods: This was a clinic-based case-control study of women aged 20-69yrs who had undergone breast screening between January 2007 and December 2013 in central Tokyo. In all, 28.8% of the participants had experience with OC use. Cases were 155 women with a pathologically confirmed diagnosis of breast cancer. Controls were the remaining 12,333 women. Results: Increased age was a significant risk factor for breast cancer (p<0.001). A lower risk was found in premenopausal women presently taking OC compared to never users (OR 0.45; 95% CI 0.22-0.90) after adjusting for age, parity and breast feeding, and a family history of breast cancer. Conclusions: Increased age rather than OC use had a greater effect on breast cancer risk. This risk may be decreased in premenopausal women with OC use, but further long-term prospective studies are necessary.