• 전기학회논문지
• /
• 제60권8호
• /
• pp.1485-1491
• /
• 2011

This paper deals with the technical problems for the protection devices, by simulating test facilities of protection coordination for Photovoltaic systems. In order to analyze the operation characteristics for the protection devices in the case that the Photovoltaic systems with bi-directional power supply are located in the feeder, this paper proposes the test facilities composed of model distribution system, protection device and model Photovoltaic systems. By performing the simulation for operation characteristics for the protection devices based on the test facilities, this paper presents the malfunction mechanism for the protection devices. The test results show that this paper is practical and effective for the technical guideline for the Photovoltaic systems.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
• /
• pp.337-340
• /
• 2003

This paper describes the operational characteristics of protection algorithm applied in distributed generations(DG) for faults occurred in the interconnected distribution networks. The DG can be Influenced by abnormal grid conditions such as disturbances occurring in the neighboring distribution feeders as well as the interconnected power line. Particularly, in case of the fault happening in the neighboring distribution feeders emanated from the substation to which DG is connected, the protective devices in the DG might mis-operate. The mis-operation of protective devices can be varied by the fault conditions. The simulation results for Hoenggye substation model composed of five feeders using PSCAD/EMTDC showed that the number of mis-operation of protective devices applied in DG is about 0.66 times per one year.

• 조명전기설비학회논문지
• /
• 제27권6호
• /
• pp.75-81
• /
• 2013

In this paper, protection coordination between residual current devices and surge protective devices in low-voltage consumer's distribution systems are presented. In the case that a surge protrctive device(SPD) is located on the load side of an residual current device(RCD), when the surge is injected from the source side of the RCD, most of injected surge currents are split into the RCD and the protection coordination between the SPD and RCD is improper, three of 6 specimens experience unintended operation due to test impulse currents. Also when the surges is injected from the load side, a lot of the surge currents is split into the SPD, but a half of test specimens causes nuisance trip. Coordination between SPD and RCD is not valid. When installing SPD, it is important to select SPD after due consideration of the protection voltage level of metal oxide varistor embedded in RCD. It is expected that the results obtained from this work could be useful to improve the protection effects of SPD in low-voltage distribution systems.

• 조명전기설비학회논문지
• /
• 제18권2호
• /
• pp.90-99
• /
• 2004

고도 정보화 사회의 발달과 함께 정보통신 설비는 빠른 전송속도를 필요로 하며, 지능형 산업설비와 행정, 금융, 교통시스템과 같은 사회시스템은 집적회로와 초소형 반도체로 구성되므로 원격감시, 조작에 의해 점차적으로 자동화 되어가고 있다. 이와 같은 현대의 초소형 전자회로는 뇌 서지에 의해 흔히 손상을 입을 수 있으며, 뇌 과전압으로부터 전자회로의 보호에 관심이 집중되고 있다. 본 논문은 일반주택에서 뇌 서지로부터 초소형 컴퓨터와 같은 전자기기의 효과적인 보호방법을 제안하기 위하여 전원계통의 접지방식에 따른 서지보호기의 보호효과를 실험적으로 분석하였다. 또한 서지보호기의 효과적인 설치방법을 조사하고 제안하였다. 기존의 설비에 추가적으로 서지보호기를 설치하는 것은 서지보호기까지의 긴 접속선으로 인한 인덕턴스 때문에 높은 잔류전압이 나타난다. 서지보호기의 설치에 있어 두 접속선을 꼬는 방법이 급격하게 상승하는 과도과전압에 매우 효과적이다.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1991년도 하계학술대회 논문집
• /
• pp.437-439
• /
• 1991

This paper deals with the development of computer programs that can be used for fuse and relay coordination in power station and also with the characteristics of these protective devices. The coordination of protective devices is determined by caculation from the lowest voltage level back to the power source. The minimum time difference between two different characteristics on the time- current curves is determined by the Golden Section searching routine.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1993년도 하계학술대회 논문집 A
• /
• pp.48-50
• /
• 1993

One of the most important functions in the distribution automation is the service restoration. This paper proposes the new method which considers not only constraints of voltage, line current and bank capacity but also the operating characteristics of protective devices such as OCR and reclosers.

• Journal of Preventive Medicine and Public Health
• /
• 제42권2호
• /
• pp.89-95
• /
• 2009

Objectives : To assess the protective effects of wearing protective devices among the residents and volunteers who participated in the cleanup of the Hebei Spirit oil spill. Methods : A total of 288 residents and 724 volunteers were surveyed about symptoms, whether they were wearing protective devices and potential confounding variables. The questionnaires were administered from the second to the sixth week following the accident. Spot urine samples were collected and analyzed for metabolites of 4 volatile organic compounds(VOCs), 2 polycyclic aromatic hydrocarbons(PAHs), and 6 heavy metals. The association between the wearing of protective devices and various symptoms was assessed using a multiple logistic regression adjusted for confounding variables. A multiple generalized linear regression model adjusted for the covariates was used to test for a difference in least-square mean concentration of urinary biomarkers between residents who wore protective devices and those who did not. Results : Thirty nine to 98% of the residents and 62-98% of volunteers wore protective devices. Levels of fatigue and fever were higher among residents not wearing masks than among those who did wear masks(odds ratio 4.5; 95% confidence interval 1.23-19.86). Urinary mercury levels were found to be significantly higher among residents not wearing work clothes or boots(p<0.05). Conclusions : Because the survey was not performed during the initial high-exposure period, no significant difference was found in metabolite levels between people who wore protective devices and those who did not, except for mercury, whose biological half-life is more than 6 weeks.

• 전기학회논문지
• /
• 제59권11호
• /
• pp.2089-2092
• /
• 2010

There are many cases that interrupt the production process because of malfunctions caused by electronic circuit boards which control equipment, but it is difficult to distinctly identify the causes in many cases. Especially, CMOS devices with the control logic circuit return automatically to normal state after their own faults. Therefore it is not easy to analyze the problems with electronic circuit boards. Recently, nuclear power plant experienced a failure due to the malfunction of electronic circuit boards and it was identified that the reason of the malfunction was because of latch-up phenomenon caused by external surge in electronic devices. This paper presents the causes and the phenomenon of latch-up by experiment and also a way using counter EMF diodes, noise filters and surge protective devices to prevent latch-up phenomenon from electronic circuit boards, finally confirms the effectiveness of the result by experiment.

• 임상간호연구
• /
• 제20권2호
• /
• pp.177-188
• /
• 2014

Purpose: This study was conducted to identify factors influencing endoscopy nurses' protective behavior against radiation exposure. Methods: Data were collected using self-report questionnaires from 122 endoscopy nurses in 21 hospitals located in Seoul, Gyeonggi province and six metropolitan cities in Korea. Collected data were analyzed using SPSS 18.0 program and included multiple regression analysis. Results: 1) There were significant relationships between protective behavior and protective environment (r=.74, p<.001), number of education sessions on radiation protection (r=.32, p<.001), number of protective devices (r=.28, p=.002), number of fellow nurses (r=.27, p=.003), and protective attitude (r=.18, p=.048). 2) Protective environment (${\beta}=0.79$, p<.001), type of hospital foundation (${\beta}=0.18$, p=.011) and marital status (${\beta}=-0.13$, p=.040) significantly predicted endoscopy nurses' protective behavior against radiation exposure (adjusted R square=.58, p<.001). The most powerful predictor for protective behavior against radiation exposure was a protective environment. Conclusion: Effective protective behavior of endoscopy nurses from radiation exposure requires improvement in their protective environment. Hospital administrators and managers should make efforts to increase protective facilities in endoscopy departments and provide endoscopy nurses with regular education on radiation protection.

• 한국전기전자재료학회:학술대회논문집
• /
• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
• /
• pp.616-619
• /
• 2004

Lightning surge damages of low voltage equipments in building are increasing due to increase in electrical and communication networks in the information-oriented society. And electronic equipments contained electrical circuits with semiconductor are very weak against lightning surge. The surge protective devices for electronic circuit in electronic equipments and AC power lines are becoming more widely. To achieve effective method of surge protection, there are needs for correlation between lightning surge protective effect of electronic equipment and installation method of surge protective device. This paper describes as a result of experiments for correlation between lightning surge protective effect and installation method of surge protective device.