• 전기학회논문지
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• 제61권10호
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• pp.1542-1547
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• 2012

Asynchronous phenomenon occurs on the synchronous generators under power system when a generator's amplitude of electromagnetic force, phase angle, frequency and waveform etc become different from those of other synchronous generators which can follow instantly varying speed of turbine. Because the amplitude of electromagnetic force, phase frequency and waveform differ from those of other generators with which are to be put into parallel operation due to the change of excitation condition for load sharing and the sharing load change, if reactive current in the internal circuit circulates among generators, the efficiency varies and the stator winding of generators are overheated by resistance loss. When calculation method of protection settings and logic for protection of generator asynchronization will be recommended, 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 asynchronizing protection, this paper describes an improved backup protection coordination scheme using a new logic that will be suggested.

• 전기학회논문지
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• 제60권11호
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• pp.2000-2006
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• 2011

Asynchronous phenomenon occurs on the synchronous generators under power system when a generator's amplitude of electromagnetic force, phase angle, frequency and waveform etc become different from those of other synchronous generators which can follow instantly varying speed of turbine. Because the amplitude of electromagnetic force, phase frequency and waveform differ from those of other generators with which are to be put into parallel operation due to the change of excitation condition for load sharing and the sharing load change, if reactive current in the internal circuit circulates among generators, the efficiency varies and the stator winding of generators are overheated by resistance loss. Where calculation method of protection settings and Logic for Protection of Generator Asynchronization will be recommended, 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 asynchronizing protection this paper describes an improved backup protection coordination scheme using a new Logic that will be suggested.

• 전기학회논문지
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• 제60권7호
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• pp.1347-1353
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• 2011

While most of the existing protection schemes have been designed with local information around individual components, these local schemes are not considered capable of protecting the modern electric power gird with growing complexity. Recent blackouts in North America and Europe have renewed the emphasis on coordinated protection and control actions to avoid systemwide blackouts, utilizing all of the available grid information. Thus, this paper proposes a new methodology, Agent-based Colored Petri Net (ACPN) modeling for systematically representing, modeling and analyzing information flows and interactions among the entities of the electric power grid. The paper demonstrates its efficacy and accuracy by investigating an ACPN model of a wide area protection system for a typical power grid. The proposed modeling and analysis schemes may further provide a framework to help assure reliability and interoperability of diverse smart grid components.

• Journal of Radiation Protection and Research
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• 제35권3호
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• pp.91-95
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• 2010

The study aimed to measure the levels of radiation protection for radiologists in medical institutions in three environmental categories (physical, administrative and social) and to establish a data base which can be used to increase awareness of environmental radiation protection in medical institutions within Korea. The study surveyed 10% of radiologists working in radiology departments in medical institutions which are supervised by the National Dose Registry overseen by the Korean Food and Drug Administration(KFDA). This study found that the level of environmental radiation protection was higher in the capital area and in larger hospitals. On the other hand, the study shows environmental radiation protection was lower in the Youngnam area and in clinics. Results from the questionnaires indicate the level of environmental radiation protection was higher when radiologists were given an individual dosimeter but lowest when the radiation protection apron quality test was conducted. Environmental radiation protection is an important factor for radiologists to conduct activities in a safe and protected environment. However, this study shows there are differences in the level of environmental radiation protection in medical institutions and location within Korea. In particular, the level of environmental radiation protection was lower in clinics, appropriate intervention strategies befitting these conditions are needed based on medical institution classification and location in order to improve the level of environmental protection.

• 방재기술
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• 통권15호
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• pp.22-27
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• 1993

The classification of hazardous area is a method of analysing and classifying the environment where explosive gas or vapour atmosphere may be expected to be present. The object of area classification is to enable the proper selection and installation of electical apparatus and other equipments. This report is intended to serve a general reference about the classification procedure of hazardous area with explanations of related Korean Standard.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1998년도 토목섬유 학술발표회 논문집
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• pp.115-122
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• 1998

• 한국엔터테인먼트산업학회논문지
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• 제13권8호
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• pp.647-659
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• 2019

본 연구는 환자의료정보 보호에 대한 의료기관 종사자들의 인식도 및 실천도의 관계를 규명하여 의료 기관의 의료정보 보호의 정책 수립에 기초자료를 제시하고자 실시하였다. 연구 결과, 연구기간 및 대상은 2019년 6월 17일부터 8월 16일까지 전라남·북도에 소재하고 있는 의료 기관 종사자 200명을 대상으로 하였다. 설문지조사는 연구자가 직접 조사 대상에게 연구 목적을 설명하고, 설문지를 배포한 후 회수하였다. 환자의료정보 직접 접촉영역 측정도구는 총 5문항, 환자의료정보 관리영역은 총 14문항, 의사소통영역은 총 8문항이었다. 연구결과, 의료기관 종사자의 영역별 환자 의료정보 보호에 대한 인식도와 실천도는 의사소통 영역이 가장 높았고, 다음으로 환자 의료정보 관리영역 의료 정보 직접접촉 영역 순이었다. 환자의료정보 보호에 대한 인식도과 실천에 관련이 있었던 변수는 의료기관 유형, 직무만족도, 종교, 근무부서와 유의한 관련이 있었다. 환자의료정보관리 영역에 영향을 미치는 요인을 알아보기 위해 환자의료정보 직접 접촉영역과 의사소통영역을 독립변인으로 환자의료정보관리 영역을 종속변인으로 하여 다중 회귀분석을 실시한 결과 환자의료정보 직접 접촉 영역과 의사소통영역이 높을수록 환자의료정보관리 영역이 높아짐을 알 수 있었다. 본 연구의 결과를 통해 의료기관 종사자들의 의료 정보 보안 및 보호 행위에 대한 인식수준을 높일 수 있도록 직종별, 직무별 교육프로그램을 개발하여 내부감사 형태의 주기적인 모니터링과 함께 지속적인 교육을 실행하여 환자 의료정보 침해 환경으로부터 환자를 보호하고 피해를 최소화 할 수 있도록 노력해야 할 것이다.

• 한국산림과학회지
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• 제111권1호
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• pp.72-80
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• 2022

본 연구는 백두대간보호구역에 대한 합리적인 보전 및 이용을 위한 권역별 지향성 설정을 위하여 실시하였다. 지향성 설정을 위해 첫 번째 단계로 자연환경보호, 자연경관보호, 농림업 진흥, 생활환경보호, 교육·문화·예술 진흥, 휴양·관광 진흥, 재난·재해관리 유형을 백두대간의 설악산, 태백산, 속리산 권역을 포함하는 유역별 지향성의 점유비율을 비교하여 결정하였다. 그러나, 7가지 지향성별로 각각의 유형이 대상지역에서 동일한 역할을 하지 않기 때문에 가중치를 적용하였다. 그 결과 백두대간 지역은 산림 및 환경보호에 대한 강력한 조치로 규제되고 있으며, 자연보호와 관련된 가중치가 다른 지역보다 높기 때문에 대부분의 지역이 자연환경보호 구역으로 분류되었다. 이상의 결과를 보완하기 위해서는 권역별 지향성과 가중치를 결정하기 위한 추가 연구 수행과 사회문화 요소 및 현장 조사 자료의 통합이 필요할 것으로 판단된다.

• Geomechanics and Engineering
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• 제28권3호
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• pp.209-224
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• 2022

In this study, the numerical analysis model of π-beam explosion is established to compare and analyze the failure modes of the π-beam under the action of explosive loads, thus verifying the accuracy of the numerical model. Then, based on the numerical analysis of different protection forms of π beams under explosive loads, the peak pressure of π beam under different protection conditions, the law of structural energy consumption, the damage pattern of the π beam after protection, and the protection efficiency of different protective layers was studied. The testing results indicate that the pressure peak of π beam is relatively small under the combined protection of steel plate and aluminum foam, and the peak value of pressure decays quickly along the beam longitudinal. Besides, as the longitudinal distance increases, the pressure peak attenuates most heavily on the roof's explosion-facing surface. Meanwhile, the combined protective layer has a strong energy consumption capacity, the energy consumed accounts for 90% of the three parts of the π beam (concrete, steel, and protective layer). The damaged area of π beam is relatively small under the combined protection of steel plate and aluminum foam. We also calculate the protection efficiency of π beams under different protection conditions using the maximum spalling area of concrete. The results show that the protective efficiency of the combined protective layer is 45%, demonstrating a relatively good protective ability.

• Ocean and Polar Research
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• 제35권4호
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• pp.291-298
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• 2013

In order to investigate the topography and exposure duration of the Siheung tidal flat, tidal ranges and DEM constructed by remote sensing techniques were analyzed. A cross-sectional diagram of the intertidal area reveals that it is relatively flat in the upper zone and then abruptly plunges into the bottom of the main channel where elevations increase in an upstream direction. The waterline during the Highest Low Water (HLW) is drawn back to the bottom of the channel at the middle part of the tidal flat and is formed along the slant of the channel during the Lowest High Water (LHW). The intertidal zone is located between -410 cm and 510 cm in terms of elevation and its total area is $0.65km^2$. An area between the Highest High Water (HHW) and Lowest High Water (LHW), occupying about 80% of the total area, occupies $0.52km^2$ of total area and accounts for 56% of the exposure duration. The boundary of wetland protection area in the Siheung tidal flat did not exactly coincide with the intertidal regime and differs by more than 15%. This study, which precisely analyzed the tidal flat area, tidal environment, and topography, would be useful in making a conservation plan and in learning how to use a wetland protection area in a sustainable manner.