• 산업경영시스템학회지
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• 제36권1호
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• pp.17-23
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• 2013

This study analyzed the efficiencies of Korean fisheries cooperative's 97 operation offices in the capital and surrounding area. We used the DEA model for checking the technical and scale efficiencies in the financial business of them. We divided the business into two parts, the productivity (efficiency for increasing deposit and loan) and profitability (efficiency for increasing the profit and reducing the risk from the loan). The results show that the additional profitability increase is very difficult because most of the offices have full technical efficiency for profitability. But additional analysis based on Slack-based Measure (SBM) DEA model shows that Kyung-Gi region can increase the profitability. SBM model analysis also gives us the possibility that customized policy can apply to each offices considering each factors affecting the productivity and profitability.

• 반도체디스플레이기술학회지
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• 제20권4호
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• pp.108-113
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• 2021

In this paper, a totem pole PFC was structured in two methods with FET and diode for low-speed switch while GaN FET was used for high-speed switch. Internal power loss, power conversion efficiency and steady-state characteristics of the two methods were compared in the totem pole bridgeless PFC circuit which is widely applied in large-capacity and high-efficiency switching rectifier of 500W or more. In order to compare and confirm the steady-state characteristics under equal conditions, a 2kW class totem pole bridgeless PFC was constructed and the experimental results were analyzed. From the experimental results, it was confirmed that the low-speed switch operation has a large difference in efficiency due to the internal conduction loss of the low-speed switch at a low input voltage. Especially, input power factor and load characteristic showed no difference regardless of the low-speed switch operation.

• 유통과학연구
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• 제15권11호
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• pp.59-72
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• 2017

Purpose - This paper evaluated the efficiency performance of the three major maritime transport markets and examined the determinants of the performance. The firms' revenue fluctuates with the changes of the economic cycle; hence it is important for them to set up business strategies to improve efficiencies. A lack of efficiency measurements for shipping firms leads to a significant gap in determining their overall performance. Research design, data, and methodology - Each of DEA scores was adopted for the evaluation and panel regression was used to examine the impact of determinants on the performance. The analysis included 50 shipping firms from three maritime transport markets as follows; 15 firms of container liners, 18 firms of bulk carrier and 17 firms of tanker carriers, and its period was from 2010 to 2016. Results - In the CCR model, container liners were the highest, tanker carriers were the second, and bulk carriers were the lowest in operation efficiency and financial efficiency. By region, operation efficiency and financial efficiency was high in the order of America, Asia, and Europe. Conclusions - This study suggests business strategies for maritime transport companies based on the analytical results of determinants of operational and financial efficiency.

• 한국산업정보학회:학술대회논문집
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• 한국산업정보학회 2008년도 추계 공동 국제학술대회
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• pp.316-321
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• 2008

In the present emerging global economy, as the focus is shifted from manufacturing to service sector, the efficiency of service operations is crucial for the county's sustainable growth and development. As one of the fastest growing service sector industries in South Korea, the call center has become an inevitable part of customer service for most companies. Despite of the strategic importance of the call center, there has been no empirical study on the efficiency of call center service operations in the literature. The main purpose of this study is to evaluate the technical efficiency of call center services so as to not only identify the current status of call center service operations, but also suggest ways to improve service operations efficiency. For this purpose, we apply a non-parametric efficiency measurement method, DEA (Data Envelopment Analysis), to domestic call centers in order to compare their relative efficiency. Based on DEA evaluations, we provided specific directions for the inefficient call centers to possibly improve their operation efficiencies. It is expected that the measurement methods suggested in this study can be applied to various issues such as service KS certification, service operations management, and the productivity analysis of service personnel.

• 대한기계학회논문집B
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• 제36권8호
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• pp.797-802
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• 2012

본 연구에서는 두 대의 히트펌프를 이용하여 $60^{\circ}C$의 난방 공급을 하는 경우에 대하여, 병렬운전을 할 경우의 성능과 직렬운전을 할 경우의 성능을 서로 비교함으로써, 직렬운전에 의한 성능 향상 가능성을 연구하였다. 두 경우의 성능을 공정하게 비교하기 위하여, 히트펌프를 구성하는 열교환기의 전열면적을 고정하였으며, 부하측 및 열원측의 입구 유량 및 온도 조건을 고정하였다. 또한, 보다 현실적인 결과를 위하여 열교환기 내 열전달 및 압력강하 특성을 고려하였다. 시뮬레이션 결과, 직렬운전 시스템의 난방성능계수가 병렬운전 시스템의 난방성능계수에 비해 본 연구의 시뮬레이션 조건 하에서 약 5% 향상 될 수 있음을 관찰하였다.

• 한국항해항만학회지
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• 제31권7호
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• pp.605-611
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• 2007

In order to become a mega hub port, major ports all over the world are making every effort to enhance their productivity through efficiency of internal operation. Accordingly, in order to enhance the competitiveness of a container terminal, an automated container terminal is considered as the best alternative. An automated container terminal is using such automated handling equipment as AGV(Automated Guided Vehicles) and ATC(Automated Transfer Crane). The efficient equipment operation plays a critical role in enhancing the productivity of an automated container terminal. In an automated container terminal, the most important equipments are AGV and ATC. Each block of containers with a vertical layout is generally operating two ATCs. The two ATCs can be crossed or not at each block. In the case of operating crossover ATC, it has an advantage of high flexibility that ATC work is possible at both TP(Transfer Point) of each block. But it has also a disadvantage that the yard has to be operated at a low storage level of containers in the terminal yard. Recently, for automated container terminals, which are being prepared for opening in Korea, they plan to use uncrossed twin ATC in order to make the storage level of their yards high at a low cost. Therefore, studies have to be made in order to increase the efficiency of twin ATC system based on the flexibility that the crossover ATC system has. This research aims to suggest an operation strategy to improve efficiency of twin ATC at each storage block in a yard.

• 사물인터넷융복합논문지
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• 제8권5호
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• pp.27-31
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• 2022

최근에 많은 글로벌 기업들이 글로벌 공급망 구축과 구축된 글로벌 공급망을 기반으로 공유경제를 실현하기 위한 노력을 수행하고 있다. 공유경제를 실현하기 위한 다양한 방법이 있으나 그 중에서도 공유물류시스템를 통한 기업의 공유경제 특히 물류효율화 추진에 많은 노력을 수행하고 있다. 기업의 공유경제를 실현하기 위해서 기업에서는 ICT 기반의 공유물류시스템 적용방안 모색이 요구되고 있다. 이에 본 연구는 물류기업체에서 ICT 기반의 공유경제의 효율을 높이기 위한 물류기업체의 물류효율화 방안을 제시하였다. 이를 위해서 ICT 기반의 공유물류시스템 적용을 위해 국내 공유물류시스템 현황 및 운영에 관해 제시하고, 공유경제 활성화에 따른 공유물류기반 운영 플랫폼 및 ICT 연계를 통한 공유물류서비스 기대효과를 제시하였다. ICT 기반의 공유물류의 효율성 방안 제시를 통한 글로벌 공급망에서 요구되는 다양한 요구를 만족할 수 있을 것으로 판단된다.

• 한국항공운항학회지
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• 제31권1호
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• pp.79-91
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• 2023

In response to the recent surge in aviation demand, major airports and aviation authorities continue to make efforts to formulate arrival and approach procedures that take into account efficient aircraft separation, noise and environmental issues of carbon (CO2) emissions. In order to ensure efficient traffic control and environmental issues, as a result, a new concept Trombone, Point Merge, etc. have been introduced and widely used in the domestic airspace. However, these new concept procedures which do not properly reflect the characteristics of the aircraft operation performance and the FMS vertical descent guidance hinder flight efficiency as well as bring in turn negative factors such as level-off flight and the use of drag device at the busiest phase of the flight descent operation, like the Continuous Descent Operation (CDO). Accordingly, throughout modification the current Standard Terminal Arrival Route (STAR) and Instrument Approach Procedure(IAP) that reflect the aircraft descent performance and the FMS guidance, the flight operation safety and efficiency is expected to be improved eventually. We herewith analyze and propose the way of improving flight efficiency in the arrival operation procedure by supplementary modification which consequently contribute to the aviation industry international competitiveness.

• 상하수도학회지
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• 제32권5호
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• pp.421-434
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• 2018

Water supply/intake pumps operation use 70~80% of power costs in water treatment plants. In the water treatment plant, seasonal and hourly differential electricity rates are applied, so proper pump scheduling can yield power cost savings. Accordingly, the purpose of this study was to develop an optimal water supply pump scheduling scheme. An optimal operation method of water supply pumps by using genetic algorithm was developed. Also, a method to minimize power cost for water supply pump operation based on pump performance derived from the thermodynamic pump efficiency measurement method was proposed. Water level constraints to provide sufficient disinfection performance in a clearwell and reservoirs were calibrated. In addition, continuous operation time constraints were calibrated to prevent frequent pump switching. As a result of optimization, savings ratios during 7 days in winter and summer were 4.5% and 5.1%, respectively. In this study, the method for optimal water pump operation was developed to secure disinfection performance in the clearwell and to save power cost. It is expected that it will be used as a more advanced optimal water pump operation method through further studies such as water demand forecasting and efficiency according to pump combination.

• 전기전자학회논문지
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• 제23권2호
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• pp.675-680
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• 2019

석탄화력발전소는 저부하에서 효율 향상을 위해 변압운전으로, 고부하에서는 정압으로 운전하는 복합변압운전 방식으로 운전하고 있으며, 복합변압운전에는 2밸브 및 3밸브 전개모드로 구분되어 운영되고 있다. 각 발전소는 제작사 권고에 따라 터빈제어밸브 모드를 선택하여 운전하고 있으나 최적의 변압운전 부하범위로 운전되고 있지 않고, 각 발전소별 부하범위 또한 상이하게 구성 되어있다. 최적의 변압운전 부하범위로 설정되지 않으면 터빈밸브 교축 손실 발생에 따른 고압터빈 내부효율 저하가 발생되어 플랜트 효율이 저하된다. 이러한 문제점을 개선하기 위해 본 논문에서는 터빈제어밸브 모드별 최적의 변압운전 부하 범위를 개선하기 위해 각 부하별 열 성능 분석 방법을 통해 최적의 부하범위를 선정하고자 한다.