• 한국정보통신학회논문지
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• 제7권7호
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• pp.1520-1526
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• 2003

본 논문에서는 마이크로프로세서를 이용하여 소비전력 모니터링이 가능한 100[W]급 직류입력/교류출력변환 인버터를 설계하였다. 또한 입출력 제어와 소비전력정보 모니터링을 외부환경에 적응적으로 대응하기 위해 퍼지추론 시스템을 설계하였다. 추론결과를 PIC16C711 프로세서에서 처리함으로서 입력전압의 변화와 소자의 온도특성 등에 적응적인 인버터 설계가 가능함을 보였다. 제작된 시스템을 이용하여 효율실험 및 부하실험을 수행하였고 오차는 2% 이내임을 확인하였다.

• 토지주택연구
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• 제11권1호
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• pp.95-101
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• 2020

In the past few decades, the global population growth and rapid economic development have resulted in significant increases in building energy consumption. To reduce greenhouse-gas emissions and building energy consumption, building materials and energy technologies must be optimized. Building retrofitting is a more efficient method than reconstruction to improve the building energy performance. In order to improve the energy performance of existing buildings, this study proposed energy-efficiency retrofit plans and derived cost-effective retrofit plan. The energy efficient retrofit method is achieved through the packaging of energy technology and the energy and cost reduction effect of the energy efficiency retrofit package are analyzed. As a result of the study, the energy-efficiency retrofit package showed an energy reduction effect of up to 60% or more and a construction cost reduction of about 30%. This study argues that optimal energy and construction cost reduction of existing buildings are possible through the packaging of energy efficiency technology.

• Journal of Electrochemical Science and Technology
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• 제12권2호
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• pp.266-271
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• 2021

A commercial PbO₂ electrode was adopted as the anode for the electrochemical degradation of the real textile effluent with the initial COD of 56.0 mg L^-1 and the stainless steel plate as the cathode. The effect of the initial pH, the electrolyte flow rate and the cell voltage on the COD, the current efficiency and the energy consumption were investigated without the addition of NaCl or Na₂SO₄. The experimental results illustrated that the PbO₂ electrode can reduce the COD of the textile effluent from 56.0 mg L^-1 to 26.0 mg L^-1 with the current efficiency of 86.1% and the energy consumption of 17.5 kWh kg^-1 (per kilogram of degraded COD) under the optimal operating conditions. Therefore PbO₂ electrode as the anode was promising to further electrochemically degrade the real textile effluent.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권10호
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• pp.4738-4753
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• 2018

Efficient rendezvous node selection and routing algorithm (RNSRA) for wireless sensor networks with mobile sink that visits rendezvous node to gather data from sensor nodes is proposed. In order to plan an optimal moving tour for mobile sink and avoid energy hole problem, we develop the RNSRA to find optimal rendezvous nodes (RN) for the mobile sink to visit. The RNSRA can select the set of RNs to act as store points for the mobile sink, and search for the optimal multi-hop path between source nodes and rendezvous node, so that the rendezvous node could gather information from sensor nodes periodically. Fitness function with several factors is calculated to find suitable RNs from sensor nodes, and the artificial bee colony optimization algorithm (ABC) is used to optimize the selection of optimal multi-hop path, in order to forward data to the nearest RN. Therefore the energy consumption of sensor nodes is minimized and balanced. Our method is validated by extensive simulations and illustrates the novel capability for maintaining the network robustness against sink moving problem, the results show that the RNSRA could reduce energy consumption by 6% and increase network lifetime by 5% as comparing with several existing algorithms.

• Nuclear Engineering and Technology
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• 제27권5호
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• pp.721-729
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• 1995

000년부터 2030년까지의 한국 원전연료주기의 최적전략을 도출하기 위하여 선형계획법을 사용하였다. 최적화를 위한 결정 인자로서는 원전연료 주기비용, 요소비용의 불확실성, 우라늄 소요량을 사용하였다. 위의 인자들을 동시에 고려하기 위하여 각각에 대한 만족도 중 최소값을 최대화하는 퍼지 의사결정기법을 이용하였다. 사용 후 원전 연료에 대한 가능한 선택대안으로는 직접처분, DUPIC, 재처리를 가정하였다. 한국의 원전연료주기 전략은 2010년경부터 재처리를 시작하여 그 처리용량을 2025년경에는 800톤까지 점차로 늘려 나가고, DUPIC 처리를 2025년경부터 시작하는 것이 최적인 것으로 나타났다. 요소비용의 불확실성과 우라늄 소요량을 고려함으로써 단순히 비용만을 고려한 경우보다 총비용은5.4%증가하나, 요소비용 불확실성은 7.1%, 우라늄 소요량은 6. d1％ 감소하는 것으로 나타났다.

• Journal of Preventive Medicine and Public Health
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• 제43권6호
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• pp.486-495
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• 2010

Objectives: The effect of meat consumption on cardiometabolic risk has been continuously studied, but their associations are not conclusive. The aim of this study is to examine the association between the consumption of meat or red meat and carotid intima-media thickness (IMT) in healthy Korean adults. Methods: This study evaluated 2374 community-dwelling adults (933 men and 1441 women) who were free of cardiovascular disease or cancer, living in a rural area in Korea. Total meat and red meat intakes were assessed with a validated 103 item-food frequency questionnaire. Carotid IMT was evaluated ultrasonographically, IMTmax was defined as the highest value among IMT of bilateral common carotid arteries. Results: After adjustment for potential confounding factors, the mean IMTmax tended to increase in higher meat consumption groups in both men and women with metabolic syndrome (p for trend= 0.027 and 0.049, respectively), but not in participants without metabolic syndrome. Frequent meat consumption (${\geq}5$ servings/week) was significantly associated with higher IMTmax in men with metabolic syndrome (by 0.08 mm, p=0.015). Whereas, the association was not significant in women (by 0.05 mm, p=0.115). Similar but attenuated findings were shown with red meat intake. Conclusions: Our findings suggest that a higher meat consumption may be associated with a higher carotid IMT in Korean adults with metabolic syndrome. The frequent meat consumption (${\geq}5$ servings/week), compared with the others, was associated with a higher carotid IMTmax only in men with metabolic syndrome. Further research is required to explore optimal meat consumption in people with specific medical conditions.

• Journal of Electrochemical Science and Technology
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• 제10권2호
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• pp.115-122
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• 2019

In order to improve the current efficiency and reduce the energy consumption in the electrosynthesis of ammonium persulfate, electrolytic properties of a perfluorosulfonic cation exchange membrane named PGN membrane and the $Al_2O_3$ ceramic membrane in the electrosynthesis of ammonium persulfate were studied and compared in a pilot electrolytic cell using a welded platinum titanium as the anode and a Pb-Sb alloy as the cathode. The effect of cell voltage, electrolyte flow rate and electrolysis time of the electrolytes on the current efficiency and the energy consumption were studied. The results indicated that the PGN membrane could improve current efficiency to 95.12% and reduce energy consumption to $1110kWh\;t^{-1}$ (energy consumption per ton of the ammonium persulfate generated) under the optimal operating conditions and the highest current efficiency of the $Al_2O_3$ ceramic membrane was 72.61% with its lowest energy consumption of $1779kWh\;t^{-1}$. Among 5 times of the electrolysis of the electrolytes, the lowest current efficiency of the PGN membrane was 85.25% with the highest energy consumption of $1244kWh\;t^{-1}$ while the lowest current efficiency of the $Al_2O_3$ ceramic membrane was 67.44% with the highest energy consumption of $1915kWh\;t^{-1}$, which suggested the PGN membrane could be used in the 5-stage electrolytic cell for the industrially continuous electrosynthesis of ammonium persulfate. Therefore the PGN membrane can be efficient to improve the current efficiency and reduce the energy consumption and can be applied in the industrial electrosynthesis of ammonium persulfate.

• 한국안전학회지
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• 제30권3호
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• pp.13-19
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• 2015

Railway vehicle equipment goes back again to the state just before when failure by the repair. In repairable system, we are interested in the failure interval. As such, a statistical model of the point process, NHPP power law is often used for the reliability analysis of a repairable system. In order to derive a quantitative reliability value of repairable system, we analyze the failure data of the air brake system of the train line 7. The quantitative value is the failure intensity function that was modified, converted into a cost-rate function. Finally we studied the optimal number and optimal interval in which the costs to a minimum consumption point as cost-rate function. The minimum cost point was 194,613 (won/day) during the total life cycle of the braking system, then the optimal interval were 2,251days and the number of optimal preventive maintenance were 7 times. Additionally, we were compared to the cost of a currently fixed interval(4Y) and the optimum interval then the optimal interval is 3,853(won/day) consuming smaller. In addition, judging from the total life, "fixed interval" is smaller than 1,157 days as "optimal interval".

• 충청수학회지
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• 제27권1호
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• pp.145-149
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• 2014

I consider the optimal consumption and portfolio selection problem with nonnegative wealth constraints using the dynamic programming approach. I use the constant relative risk aversion (CRRA) utility function and disutility to derive the closed-form solutions.

• 대한물리치료과학회지
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• 제15권1호
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• pp.21-28
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• 2008

The purposes of this study are to quantify energy expenditure by measuring oxygen consumption while performing occupational therapy activities most commonly used for adult hemiplegia patients, to recommend a optimal dosage of exercise by comparing energy expenditure according to the recovery stage, and to suggest a precaution in the treatment of patients with cardiac disorders. According to Brunnstrom recovery stages in hand function, subjects were allocated to group I(3rd and 4th Brunnstrom recovery stages) and group II(5th and 6th Brunnstrom recovery stages). Outcome measures included oxygen consumption, energy expenditure rate, and heart rate during each activity and in recovery period after the activity. Occupational activities including sanding activity, putty activity, and skateboard activity were carried out for all patients. In sanding and putty activities, there were significant differences of oxygen consumption and energy expenditure during the activity between groupⅠandⅡ(p<0.05), but there were not significant differences of oxygen consumption, energy expenditure and heart rate in the recovery period(p>0.05). In skateboard activity, there were no significant differences in oxygen consumption, energy expenditure and heart rates between the two groups during the activity and in the recovery period(p>0.05). The findings indicates that cardiovascular demands for basic activities usually peformed for a treatment may be depended on the physical recovery of patients with hemiplegia. Therefore, therapeutic activities for patients should be selected with the great care.