• 대한전기학회:학술대회논문집
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• 대한전기학회 2015년도 제46회 하계학술대회
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• pp.335-336
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• 2015

Voltage collapse is one of the main threats in power system operation and it is a result of a very low voltage profile in one or multiple areas in the power system network. Hence, the need for proper coordination among transmission and generator operators to maintain voltage stability if of paramount importance. In this paper, the different voltage and reactive power operating guidelines and criteria of various electric reliability councils, coordinating councils, transmission system operators and other electric utilities are discussed. Among these are NERC, ENTSO-E, WECC, PJM and ERCOT. A comprehensive comparison is also made to the existing Korean power system voltage reliability guidelines. Furthermore, this paper presents a set of voltage and reactive power guidelines that can help in determining voltage limits that can improve the reliability of the Korean power system operation.

• 전력전자학회논문지
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• 제23권4호
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• pp.265-272
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• 2018

This paper proposes a new control method for the supercapacitor (SC) to compensate the pulsed load and to enhance the power quality of the DC microgrid. By coordinating the operating frequency, the SC is controlled to handle the surge current, while the low-frequency current component is dealt with by the remaining sources in the system. The operation mode of the SC unit is automatically changed based on the state of charge and DC bus voltage level. Meanwhile, the mismatch in the power demand is covered by the SC unit by regulating the DC bus voltage level. The effectiveness of the proposed method is verified experimentally by the prototype with two distributed generators and one SC unit.

• 대한산업공학회지
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• 제21권1호
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• pp.137-151
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• 1995

A difficult problem in operating Flexible Manufacturing Systems (FMS) is to control the system in real-time by coordinating heterogeneous machines and integrating distributed information. The objective of the paper is to present the models and methodologies useful to resolve the difficult problem. The detailed objectives can be described in three folds. First, a hierarchical Colored and Timed Petri-Net (CTPN) is designed to control an FMS in real-time. The concerned FMS consists of a loading station, several machining cells, a material handling system, and an unloading station. Timed-transitions are used to represent the timed-events such as AGV movements between stations and cells, part machining activities in the cells. Signal places are also used to represent communication status between the host and the cell controllers. To resolve the event conflicts and scheduling problems, dispatching rules are introduced and applied. Second, an implementation methodology used to monitor and diagnose the errors occurring on the machines during system operation is proposed. Third, a Petri-Net simulator is developed to experiment with the designed control logic.

• 수산해양교육연구
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• 제16권1호
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• pp.124-141
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• 2004

This study focuses on the off-shore trawl fishery, specifically on its restructuring and new regulations governing its operation since the 1990s. This fishery has an important role in terms of fishing capacity and production amount and is dependent on close diplomatic relations with adjacent fishing countries. The off-shore trawl fishery has been shrinking since the 1990s. In addition to a decrease in stock and an increase in imports, there are vessel buyback programs and a decrease in fishing grounds related to a tri-lateral agreement among Korea, China and Japan which have sped up the shrinking of the fishery. In this processing, costs exceed the increase of revenue. Excess investments in fishing gear and salary for crews have lowered profits in this fishery. Considering the above, the off-shore otter trawl fishery should stop increases in production and restructure the fishery by coordinating fishing gear restrictions and fishing areas, and down-sizing management capacity.

• Journal of Power Electronics
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• 제13권1호
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• pp.51-58
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• 2013

This paper proposes the power conversion mechanism of a bailer-charge-transfer zero-current-switching (CT-ZCS) circuit. The operation modes are analyzed and researched using state trajectory equations. The topology of CT-ZCS based on soft-switching inverters offers some merits such as: tracking the input reference signal dynamically, bearing load shock and short circuit, multiplying inverter N+1 redundancy parallel, coordinating power balance for easy control, and soft-switching commutation for high efficiency and large capacity. These advantages are distinctive from conventional inverter topologies and are especially demanded in AC drives: new energy generation and grid, distributed generation systems, switching power amplifier, active power filter, and reactive power compensation and so on. Prototype is manufactured and experiment results show the feasibility and dynamic voltage-tracking characteristics of the topology.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.1340-1345
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• 2009

Ministry of Land, Transportation and Maritime Affairs has implemented Construction CALS project for improving informationization level of construction industry and for making construction production system efficient. Although an importance of evaluation on level and performance of construction informationziation projects has been emerged, Construction CALS hasn't been evaluated so far. In this study, the performance indicators of construction CALS as the most important base in creating a performance management system were deduced. For this aim, this study reviewed the former researches on system construction for managing performance, analyzed current status of Construction CALS, arranged the relationship between upper strategies and ISP, developed pools of performance indicators, and this study followed IT BSC methodology. As a result, this study developed performance indicators of Construction CALS through four strategies such as globalization and activation of Construction CALS standards, research & development for reaching to international level in construction informationization technology, stabilization of system operation and distribution by publicizing Construction CALS and improving its functions, and policy implementation for managing and coordinating Construction CALS projects. These indicators will be applied to build a system of performance management.

• 대한간호학회지
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• 제36권6호
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• pp.942-949
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• 2006

Purpose: This study was to investigate the knowledge and learning needs of chemotherapy in gynecological cancer patients. Method: The subjects consisted of 103 gynecological cancer patients receiving chemotherapy from April 2005 to August 2005. Data was collected using a questionnaire about knowledge and learning needs of chemotherapy. The data was analyzed by t-test, ANOVA, Scheffe test, and Pearson's correlation coefficient using SAS. Result: Average scores of knowledge and learning needs of general treatment and care were 2.74, and 3.30 respectively. Average score of knowledge and learning needs of chemotherapy were 2.54 and 3.23 respectively. Learning needs of general treatment and care and of chemotherapy were significantly different in relation to marital status, educational level, family support, the operation, and the amount of chemotherapy received. Items with the highest level of learning needs were the symptoms of recurring illness of general treatment, and minimizing side effects of chemotherapy. There were a negative correlation between knowledge and learning needs on general treatment and a positive correlation between knowledge and learning needs on chemothearpy but there were not significant statistically. Conclusion: The level of learning needs related to cancer treatment was high, whereas, that of knowledge was low. Therefore, when designing an educational program for gynecological cancer patients, understanding of learning needs is necessary. Also, consideration of a patient's characteristics, and a systematic and detailed educational program should be provided.

• 한국경영과학회지
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• 제35권1호
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• pp.83-95
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• 2010

This paper considers a firm that operates make-to-stock and make-to-order facilities in successive stages. The make-to-stock facility produces components which are consumed by the external market demand as well as the internal make-to-order operation. The make-to-order facility processes customer orders with the option of acceptance or rejection. In this paper, we address the problem of coordinating how to allocate the capacity of the make-to-stock facility to internal and external demands and how to control incoming customer orders at the make-to-order facility so as to maximize the firm's profit subject to the system costs. To deal with this issue, we formulate the problem as a Markov decision process and characterize the structure of the optimal inventory allocation and customer order control. In a numerical experiment, we compare the performance of the optimal policy to the heuristic with static inventory allocation and admission control under different operating conditions of the system.

• 한국가금학회지
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• 제12권2호
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• pp.119-126
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• 1985

The purpose of the study is to review the evolutional process of the U.S. broiler industry into the integrated production and marketing systems and to examine the factors influenced such a structural change over the Past half a century. The study is also carried out under the consideration that the experience gained by the integrated U.S. broiler industry could be utilized in applying the system to any non-integrated broiler industries like one in Korea. The U.S. broiler industry has been prevailed in the typical independent operation of all stages, from factor supply through growing to dressing and marketing until such time as growers began to suffer from financial difficulties right after the end of the World Wat II due mainly to lowered price of broilers stemmed from whopping decrease of the demand, which eventually reflected to the allied agribusiness sectors. The feed business field was the first reactor to this situation so that a kind of measures was taken to cope with the problems faced in such a way to provide extended credit on feeds first and help obtain chicks or sell broilers later. This trend has been practiced for broiler related agribusiness through late 1940's to work together with growers by coordinating its function between two or more stages involved in broiler production and marketing process as a means of spreading risk and sharing profit between stages Participated. The integrated system and contract farming thus became Popular across the country through mid 1950's.

• 한국비블리아학회지
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• 제33권4호
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• pp.115-137
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• 2022

본 연구는 중등 학교도서관 북큐레이션 사례 조사와 담당자의 북큐레이션에 대한 인식 분석을 통해 중등 학교도서관 북큐레이션 활성화 방안을 제시하는 데 목적이 있다. 문헌조사와 함께, 인천광역시교육청 중등 학교 중 상시 운영이 이루어지는 전수 192개 학교도서관 담당자를 대상으로 설문조사, 인천 중등 사서교사 4명과 문헌정보학과 교수 1명을 대상으로 인터뷰, 학교도서관 방문 관찰을 병행하였다. 이를 통해 북큐레이션 활성화 방안으로 학교도서관 담당자의 증원, 교과교사와의 협력과 정보 공유, 북큐레이션 운영을 위한 매뉴얼 확립, 주제 선정 사례집 출판을 제안하였다.