• Journal of Electrical Engineering and Technology
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• 제12권2호
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• pp.502-512
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• 2017

The presence of DGs in power system networks tends to negatively affect the protective relays coordination. The proposed method introduces an approach to minimize the numbers of relays that acquire new settings on contrary to their original settings (case without DG), to achieve relays coordination in case of adding DG, since relays coordination with minimum number of relays of re-adjusted settings represents economical target, especially in networks containing mixture of electromechanical and adaptive digital relays. The scheme decides the possible minimum number of re-adjusted relays and their locations in an optimum manner to achieve proper relays coordination in case of adding DGs. The proposed approach is divided into two successive phases; the first phase is stopped when the first relays coordination solution is achieved. The second phase increases the possibility to keep higher number of relays at their original settings than that obtained in first phase through achieving multi solutions of relays coordination. The proposed approach is implemented and effectively tested on the well-known IEEE-39 bus test system.

• Transactions on Electrical and Electronic Materials
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• 제18권3호
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• pp.169-175
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• 2017

A safe and reliable protection system in distribution networks, specifically, those hosting distribution generation units, needs a robust over-current protection scheme. To avoid unintentional DG disconnection during fault conditions, a protection system should operate quickly and selectively. Therefore, to achieve this aim, satisfying coordination constraints are important for any protection scheme in distribution networks; these pose a challenging task in interconnected and large-scale networks. In this paper, a new coordination strategy, based on the same non-standard time-current curve for all relays, in order to find optimal coordination of directional over-current relays, is proposed. The main aim is to reduce violations, especially miscoordination between pair relays. Besides this, the overall time of operation of relays during primary and backup operations should be minimized concurrently. This work is being tackled based on genetic algorithms and motivated by the heuristic algorithm. For the numerical analysis, to show the superiority of this coordination strategy, the IEEE 30-bus test system, with a mesh structure and supplemented with distributed generation, is put under extensive simulations, and the obtained results are discussed in depth.

• 국제학술발표논문집
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• The 3th International Conference on Construction Engineering and Project Management
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• pp.628-634
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• 2009

It is a common practice in Hong Kong for the main contractors of local building projects to sublet most of the work to subcontractors. Consequently their roles have gradually transformed from a constructor to a manager of subcontractors. The outcomes of a project therefore depend heavily on the subcontractors' performance. However, most of the subcontractors complain that they are unable to efficiently and effectively operate due to site coordination problems, such as inaccurate site reference lines, caused by main contractors. The site problems may consume significant amounts of resources if practical solutions cannot be agreed by the project participants early enough. Rahim Organizational Conflict Inventory-II (ROCI-II) model was developed by M.A. Rahim that measure five types of conflict management style including Integrating, Obliging, Dominating, Avoiding and Compromising. This paper presents the questionnaire survey based on the ROCI-II model to rank the preference on the conflict management style adopted by the project representatives of the subcontractors in handling the site coordination problems and its impact to the time used to agree the solutions to the different types of site coordination problems with main contractor. The survey results show that most of the subcontractors' project representatives preferred to adopt the Compromising style to tackle the site coordination problems and the time used to agree the solutions with main contractor was influenced by the conflict management style adopted.

• 한국안광학회지
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• 제19권3호
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• pp.371-376
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• 2014

목적: 최근 보고된 Lee-Ryan Eye-Hand Coordination(EHC) Test를 이용하여 정상안의 인위적 시력저하가 눈-손 협응능력(EHC)에 미치는 영향을 알아보고자 하였다. 방법: 정상시력을 가진 성인 11명($29.46{\pm}5.94$세)을 대상으로 비우위안에 볼록렌즈를 가입하여 인위적으로 근거리 약시 상태를 만들어 EHC를 검사하였고, 2주 후 정상 시력상태에서 다시 검사를 하였다. EHC를 알아보기 위해 Lee-Ryan EHC Test의 각기 다른 난이도의 7가지 모양을 선택하여 총 소요시간과 에러 횟수를 EHC의 분석 요소로 비교 분석하였다. 결과: 총 소요시간에서는 인위적으로 시력 저하된 눈이 정상 단안 시력보다 더 많은 시간을 소비하였고(p=0.013), 양안시 상태에서는 오히려 정상안 상태보다 저하된 시력을 가지고 더 빨리 검사를 끝마쳤다(p=0.001). 에러 횟수에서는 소요시간과 같이 저하된 시력이 더 많은 실수를 하였으나(p<0.001), 인위적으로 저하된 시력을 가진 상태에서 단안과 양안시의 차이는 보이지 않았다. 결론: 기존의 EHC 방법들이 갖고 있는 적용하는데 있어서의 한계들과 달리 간단한 컴퓨터 시스템을 기반으로 한 Lee-Ryan EHC Test로도 EHC의 이상(deficit)을 관찰 할 수 있었다. 후에 약시와 같은 시력저하에 관련된 분야에 더 많은 연구가 이루어 질 것으로 사료된다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 하계학술대회 논문집 A
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• pp.476-478
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• 2001

Coordination under short-circuit conditions is a systematic application of protective devices in the electrical power system, which, in response to a fault, will remove only a minimum amount of equipment from service. The objective is not only to minimize the equipment damage and process outage costs, but also to protect personnel from the effects of these failures. The coordination study of an electric power system consists of an organizes time-current study of all devices in series from the utilization device to the source. This study is a comparison of the time it takes the individual devices to operate when certain levels of normal or abnormal current pass through the protective devices. The objective of a coordination study is to determine the characteristics, ratings, and settings of overcurrent protective devices that will ensure that the minimum unfaulted load is interrupted when the protective devices isolate a fault or overload anywhere in the system. At the same time, the devices and settings selected should provide satisfactory protection against overloads on the equipment and interrupt short-circuit as rapidly as possible.

• 전기학회논문지
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• 제60권1호
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• pp.43-49
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• 2011

A distance relay scheme is commonly used for backup protection. This scheme, called a step distance protection, is comprised of 3 steps for graded zones having different operating time. As for the conventional step distance protection scheme, Zone 2 can exceed the ordinary coverage excessively in case of a transformer protection relay especially. In this case, there can be overlapped protection area from a backup protection relay and, therefore, malfunctions can occur when any fault occurs in the overlapped protection area. Distance relays and overcurrent relays are used for backup protection generally, and both relays have normally this problem, the maloperation, caused by a fault in the overlapped protection area. Corresponding to an IEEE standard, this problem can be solved with the modification of the operating time. On the other hand, in Korea, zones are modified to cope with this problem in some specific conditions. These two methods may not be obvious to handle this problem correctly because these methods, modifying the common rules, can cause another coordination problem. To overcome this problem clearly, this paper describes an improved backup protection coordination scheme using an IEC 61850-based distance relay for transformer backup protection. IEC 61850-based IED(Intelligent Electronic Device) and the network system based on the kernel 2.6 LINUX are realized to verify the proposed method. And laboratory tests to estimate the communication time show that the proposed coordination method is reliable enough for the improved backup protection scheme.

• 한국의류학회지
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• 제29권5호
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• pp.703-714
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• 2005

The purpose of this study is to acquire various methods for the fashion image coordination and to examine common features of variation of coordination methods according to the trend. It has attained by investigating Men's fashion image coordination through trend analysis in terms of its coordination features and its variety aspects. For this study, it has classified into twelve typical Men's fashion images in collecting 1,291 pieces of photographs on the subject of jackets and pants from Men's fashion collection$(1995\~2002)$. The study has examined methods and features of fashion image coordination by year according to design elements and the harmony between items. In addition, it has drawn common factors in the image coordination. The summary and conclusion are as follows. A year of 1995, it has presented as the essential code of the variation that morphologic aspects of a design in the fashion image coordination. Various designs have developed through the variation of shapes such as shoulder width, shoulder pad, jacket width and its length and so on. In the initial stage, the width of shoulder and jacket has fitted into large pattern and then adjusted elegantly to make fit the body that indicates a dissolution according to an avant-garde image. At the time that over-measurement of the shape has reduced and high quality and variation of materials has gradually become significant. Those are often used that high-quality glossy materials or other materials which are opposite to the basic code of the original fashion image materials and qualities regardless of images. On the pattern and color, in addition, have represented neat and elegant impression with moderate applications rather than quantitative abundance that have used opposite elements to the basic code f3r the change code like materials. Furthermore, before and after 1999, ' it shows that a concept of the total coordination has arisen that increased coordination methods to strengthen and affluent its images for the whole with wearing accessaries such as hats, gloves, sunglasses, mufflers, bags, belts and so on.

• 한국사회복지학
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• 제57권4호
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• pp.91-118
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• 2005

본 연구는 OECD 14개 회원국을 대상으로 복지체제와 생산체제의 조정전략과 이들 사이의 제도적 상보성이 소득 불평등에 미치는 영향을 분석하는 것이 목적이다. 분석에 포함된 기간은 1980년에서 1997년이며, 분석방법은 벡과 카츠(Beck and Katz, 1995)가 제안한 PCSE(Panel Corrected Standard Errors) 방법이 사용되었다. 제도적 상보성은 분배조정과 생산조정 변수의 상호작용 항으로 분석된다. 본 연구의 결과 제도적 상보성 수준이 높을 경우가 그렇지 않을 경우보다 소득불평등 수준을 낮추는 것으로 분석되었다. 또한, 조정전략의 관점에서 볼 때, 분배조정 영역과 생산조정 영역이 모두 전략적 조정을 지향하도록 제도가 구성될 때 소득 불평등 정도를 더 낮추는 것으로 분석되었다. 즉, 복지체제 영역에서 전략적 조정을 지향하는 정책 변화는 생산체제 영역에서 전략적 조정을 증가시키는 정책 변화가 같이 진행될 때 소득 불평등 수준을 더 낮출 수 있다는 것을 확인하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2001년도 춘계학술대회 논문집 전력기술부문
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• pp.132-135
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• 2001

To improve the fault coordination of underground distribution line we study the several contents such as the magnitude of fault current in distribution line tripping time of CB by acting of over current relay with instantaneous trip and time delay trip. We also examine the melting time of current limiting fuse inside power fuse Through the research as above. we suggest the modification scheme of fault coordination to reduce the interruption times of power failure.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1993년도 하계학술대회 논문집 A
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• pp.406-409
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• 1993

Integration of intelligent robot workcell is now a hot issue in CIM and robotics area. This paper dealt with relatively low level essential topics. i. e., multi-robot coordination and real-time communication for the integration of intelligent robot workcell. For the coordination of multi-robot system, the tightly-coupled coordination is proposed using the various sensors. In order to handle the numerous communication data, time-critical communication network (field-bus) is introduced and investigated. Finally, intelligent robot workcell is suggested using the mini-MAP and field-bus.