• Journal of Power Electronics
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• 제7권4호
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• pp.301-309
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• 2007

The flyback converter is one of the most attractive isolated converters in small power applications because of its simple structure. However, it suffers from high device stress, large transformer size, and high voltage stress across its switch and diode. To solve these problems a new cost-effective PWM single-switch isolated converter is proposed. The proposed converter has no output filter inductor, reduced voltage stress on the secondary devices, and reduced transformer size. Moreover, the switch turn-off loss is reduced and no dissipative snubber across the secondary diode is required. Therefore, it features a simple structure, a low cost, and high efficiency. The operational principle and characteristics of the proposed converter are presented and compared with the flyback converter and then verified experimentally.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 하계학술대회 논문집
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• pp.289-292
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• 2007

The flyback converter is one of the most attractive isolated converters in small power applications because of its simple structure. However, it suffers from high device stress, large transformer size, and high voltage stress across switch and diode. To solve these problems a new cost-effective PWM single-switch isolated converter is proposed. The proposed converter has no output filter inductor, reduced voltage stress on the secondary devices, and reduced transformer size. Moreover, the switch turnoff loss is reduced and no dissipative snubber across the secondary diode is required. Therefore, it features a simple structure, low cost, and high efficiency. The operational principle and characteristics of proposed converter are presented compared with flyback converter and verified experimentally.

• 오토저널
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• 제14권6호
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• pp.113-126
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• 1992

Recently the multi-kind, small-amount manufacturing system has been replacing the mass manufacturing system, and domestic machining inustry also is eager to absorb the new technology because of its high productivity and cost reduction. The optimization of the cutting condition has been a vital problem in the machining industry, which would help increase the productivity and raise the international competitiveness. It is intended in this study to investigate the machining costs per unit time which is essential to the analysis of the optimal cutting condition, to computer the cutting speed that lead to the minimum machining costs and the maximum production to suggest the cutting speed range that enables efficient speed cutting, and to review the machining economy in relation to cutting depth and feed. Also considered are the optimal cutting speed and prodution rated in rrelation with feed. It is found that the minimum-cost cutting speed increases and the efficient cutting speed range is reduced as machining cost per unit time increases since the cutting speed for maximum production remains almost constant. The machining cost is also lowered and the production rate increases as the feed increases, and the feed should be selected to satisfy the required surface roughness. The machining cost and production rate are hardly affected by the cutting depth if the cutting speed stays below 100m/min, however, they are subject to change at larger cutting depth and the high-efficient speed range also is restricted. It can be established an adaptive optimal cutting conditions can be established in workshop by the auto-selection progam for optimal operation. It is expected that this method for choosing the optimal cutting conditions might contribute to the improvement of the productivity and reduced the cost. It is highly recommended to prepare the optimal cutting conditionthus obtained for future use in the programing of G-function of CNC machines. If proper programs that automatically select the optimal cutting conditions should be developed, it would be helpful to the works being done in the machine shops and would result in noticeable production raise and cost reduction.

• 한국의료질향상학회지
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• 제6권1_2호
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• pp.150-160
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• 1999

Background : Because hospitals had to faced with financial hardship, we have to have more effective hospital management. In this study, we tried to improve job performance and to reduce cost maintaining safety in fields of patients care. Methods : Central Supply Room(CSR) staffs taught strategy of material cost reduction to middle level managers and staffs 14 times. All staffs and voluntary service workers, working in 33 nursing units, participated in this activity. We developed questionnaire to check the degree of participate in cost reduction activity and job performance in CSR, and quality improvement in the wards. Two hundred questionnaires were distributed and 197 returned. Results : Because CSR staffs developed new items and every item was managed at each department, stocks of each department were reduced. Overall, by comparing before and after cost reduction activity, almost 1.2 billion won reduced for one year. Staffs' loyalty and spirits of cost reduction were improved by changing clothes and duty environment. Furthermore, these activity improved patients' satisfaction. Conclusion : We suggest that CSR activity in a university hospital contributes to improve job performance and to reduce cost without any problem in patient care.

• 한국건축시공학회지
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• 제13권4호
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• pp.321-332
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• 2013

건축물의 생애주기비용은 시행과정 전 단계에서 상호 연관되어 비용이 발생하며 각 단계마다 서로 간에 영향력이 존재한다. 하지만 건축 프로젝트의 각 단계별 CBS가 서로 상이하여 합리적인 공사비를 산정하는데 문제점이 발생한다. 따라서 본 연구에서는 기존에 연구되었던 LCCBS를 바탕으로 건축 프로젝트 각 단계 간에 경계조건을 분석하였다. 또한 분석된 경계조건을 바탕으로 분절요인을 분석하고 이에 따른 연계방안을 모색하였다. 연계방안의 유효성 검증을 위해 실제 건축프로젝트를 바탕으로 사례적용을 실시하였다. 분석결과 누락되는 항목이 97.2%이상을 개선하였고 평균 6시간 빠르게 업무를 수행할 수 있음을 확인할 수 있었다. 향후, LCC 시스템에 적용함으로써 LCC의 효율적인 산정 및 LCC 절감을 계획할 수 있을 것으로 사료다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1992년도 가을 학술발표회 논문집
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• pp.191-195
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• 1992

Optimization of the RC pile cap for high rise apartment building has been performed with the aim of the cost minimization. The principle of divided parameters has been used. As a result the cost has been reduced by 25percentage.

• Journal of Advanced Marine Engineering and Technology
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• 제40권4호
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• pp.342-347
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• 2016

본 논문에서는 실습선과 함정의 광원으로 80 % 이상을 차지하는 백열등 및 형광등기구를 대체하기 위한 선박용 LED 등기구의 경제성 분석에 관하여 기술하였다. 소비전력, 초기투자비용, 유지비용 및 유류비에 대한 절감률을 분석하였고, 탄소배출량과 손익분기점을 산출하였다. 실습선의 초기투자비용은 3.8배 상승하였지만, 5년간 유지비용은 51 % 절감되었다. 40 %, 50 % 및 60 %의 점등률에 따른 손익분기점은 각각 11개월, 9개월 및 7개월로 산출하였다. 함정의 초기 투자비용은 3.5배 상승하였지만, 5년간 유지비용은 55 % 절감되었다. 40 %, 50 % 및 60 %의 점등률에 따른 손익분기점은 각각 15개월, 12개월 및 10개월로 산출하였다. 또한 실습선과 함정의 탄소배출량은 각각 69 % 및 65 % 절감되었다. 이러한 결과를 통하여 실습선과 함정에 LED 등기구를 적용한다면, 50 % 이상의 유지비용 절약과 60 % 이상의 소비전력, 유류비 절감 및 탄소배출량이 감소될 것으로 판단된다.

• Journal of Electrical Engineering and Technology
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• 제10권3호
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• pp.1015-1024
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• 2015

This paper introduces a low cost, high efficiency, high performance three-phase unified power quality conditioner (UPQC) by using four-switch three-phase inverters (FSTPIs) and an extra capacitor in the shunt active power filter (APF) side of the UPQC. In the proposed UPQC, both shunt and series APFs are developed by using FSTPIs so that the number of switching devices is reduced from twelve to eight devices. In addition, by inserting an additional capacitor in series with the shunt APF, the DC-link voltage in the proposed UPQC can also be greatly reduced. As a result, the system cost and power loss of the proposed UPQC is significantly minimized thanks to the use of a smaller number of power switches with a lower rating voltage without degrading the compensation performance of the UPQC. Design of passive components for the proposed UPQC to achieve a good performance is presented in detail. In addition, comparisons on power loss, overall system efficiency, compensation performance between the proposed UPQC and the traditional one are also determined in this paper. Simulation and experimental studies are performed to verify the validity of the proposed topology.

• 상하수도학회지
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• 제27권1호
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• pp.129-138
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• 2013

Water interruption is often caused by a rupture in the branch-like singular pipeline. This will cause critical complaints from household and may decrease public service quality. As an alternative of singular pipeline, additional parallel pipeline could be installed for sustainable water supply. This system is called double pipeline system and able to be utilized for water transmission line between treatment plant and distribution reservoir. Construction of double pipeline was thought to increase capital cost, which can be an issue to waterworks authorities. Reducing capital cost was possible by means of installing connectors between two parallel pipelines because of reduced diameter of each pipe. To obtain optimal design condition for connectors, it was necessary to compare water pressure according to accident location, to investigate flow according to connection pipe spacing, connection pipe diameter, and aging of pipe. Reliable and economical connection layouts were determined based on these results. The cost estimation for each design condition was carried out. Cost was approximately reduced by 20 ~ 30 % compared to the double pipeline without connections. In addition to this, connection between double pipelines could expect extra benefits for maintenance since the pipe could be repaired and rehabilitated without interruption.

• 수산해양기술연구
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• 제48권4호
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• pp.346-351
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• 2012

The fuel cost of fishing lights for squid jigging fishing vessels takes about 30% of total fishing costs and over 65% of total fuel costs, which indicates the necessity of development of cost-reducing and high efficient fishing light system. This study aimed to analyze the economic effectiveness of LED fishing light systems in combination with metal halide lamp for the squid jigging fishery. Analytical results showed that the level of fishing profits of vessels using LED lights could be different with those of vessels using metal halide lights. That is, when a fuel cost could be reduced by 30%, fishing profits of vessels using LED lights might be the same as those of vessels using metal halide lights, and fishing profits of vessels using LED lights could be higher than those of vessels using metal halide lights when a fuel cost could be reduced by 50%.