• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2007년도 추계학술대회 논문집
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• pp.478-479
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• 2007

Many electrical fires are occurred by leakage currents and sparks generated by a short circuit. Earth leakage circuit breakers (ELCBs) should be tripped at the moment of the faults mentioned above. In this paper, we described the tripping characteristics of ELCBs against parallel arcing faults. A diesel engine generator with the capacity of 375 kVA source was adopted to provide enough large current when a parallel arcing occurred. The experimental results showed that most ELCBs we experimented were not tripped against short-duration pulse currents produced by parallel arcing because the ELCBs are designed to be tripped by a large current with long duration similar to power frequency.

• 한국화재소방학회논문지
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• 제34권3호
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• pp.43-48
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• 2020

본 연구에서는 누전경보 기능이 내장된 누전경보차단기(JER-E2S, ETECKOREA Co., Korea)를 개발하고, 그 특성을 분석하였다. 개발된 누전경보차단기는 단상 220 V 전용으로 정격전류는 32 A, 20 A, 20 A(화장실용), 16 A 등이다. JER-E2S는 기존 누전차단기(ELB)의 특성을 모두 만족하고 있으며, 13 ± 2 mA의 저항성누설전류(Igr)인 화재전류가 전선로에 흐르면 실시간 검출하여 LED 램프로 위험 상태를 점멸할 수 있는 제품이다. 개발된 누전경보차단기는 LED 램프 및 통신기기 등에서 필연적으로 발생되는 용량성누설전류(Igc)에 대한 내성이 있어서 안정적인 전기 공급이 가능하다. 또한, 누전경보차단기는 순간지락 정전보호 기능이 있어서 작은 물방울 및 나뭇잎 등의 순간지락에 따른 차단기의 오동작 없이 전원 공급이 가능하다. 그리고 개발된 누전경보차단기의 대기전력은 0.1 W 이하로 기존 ELB에 비해 절전 성능이 3~8배 우수한 특성을 나타냈으며, 일반 120 ㎡의 아파트 1 세대에 10개 정도의 누전경보차단기가 설치되었을 때 1 개월에 2~5 kWh의 전기를 절감할 수 있다. 개발된 누전경보차단기는 기존 누전차단기의 특성을 만족할 뿐만 아니라 전기화재 예방기능 및 오동작 방지기능이 있어서 전원 품질이 우수하고, 전기화재 예방에 혁신적으로 기여할 수 있는 제품이다.

• 대한전기학회논문지:전기물성ㆍ응용부문C
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• 제53권9호
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• pp.464-469
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• 2004

The leakage current of transmission insulators contaminated with salt, clay, and kaolin was examined in the Gochang's Long Periods Testing Center. The Insulators were artificially contaminated and estimated with the method of equivalent salt deposit density(ESDD). The artificially contaminated insulators were installed with the same condition as in the real transmission power line and applied with 154 (kV). The leakage current of the artificially contaminated insulators was measured with environment conditions, such as temperature and humidity by the a automatic leakage current detecting system. The leakage current of heavily contaminated insulator was abruptly increased above 72［%］ of humidity, even though the leakage current was similar between the contaminated and non-contaminated insulators below 72［%］ of humidity. Also, it was found that the humidity was much more important than the temperature in the leakage current of transmission insulators. The leakage current of contaminated insulator was decreased when it was plenty of rainfall, resulting from natural washing.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2004년도 학술대회지
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• pp.460-462
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• 2004

The control of the data retention time is a main issue for realizing future high density dynamic random access memory. There are several leakage current mechanisms in which the stored data disappears. The mechanisms of data disappear is as follow, 1 )Junction leakage current between the junction, 2) Junction leakage current from the capacitor node contact, 3)Sub-threshold leakage current if the transfer transistor is affected by gate etch damage etc. In this paper we showed the plasma edge damage effect to find out data retention time effectiveness. First we measured the transistor characteristics of forward and reverse bias. And junction leakage characteristics are measured with/without plasma damage by HP4145. Finally, we showed the comparison TRET with etch damage, damage_cure_RTP and hydrogen_treatment. As a result, hydrogen_treatment is superior than any other method in a curing plasma etch damage side.

• 상하수도학회지
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• 제24권5호
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• pp.495-508
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• 2010

The aim of this study is to develop a quantified water loss Index to evaluate and manage leakage scientifically for the reduction of non-revenue water in water distribution systems. For the purpose, unavoidable background leakage suggested from UK water industry and IWA, and allowable water leakage in accord with the concept of allowable water loss are proposed by analyzing the inflow into two study water districts and the short-term water use of each customer in the districts. The study distribution areas are selected among the metered districts with good maintenance of leakage after improvement activities in Nonsan, medium sized city in Korea. Estimation models of allowable leakage are developed by metering and analyzing the minimum night flow at residential and commercial areas in the city. In the results of the investigation, it is estimated that background night flow in residential area was larger than that of commercial area where the types of business shows small water use characteristics. Meanwhile, night flow and background water loss on internal plumbing systems show great differences for each district which is influenced much by the water use characteristics and facilities scale. Based on metering water use data in various districts, leakage management criteria can be established under the consideration of domestic conditions in Korea by analyzing separated real water use and background leakage and it is possible to apply into presentation of optimal leakage level and reasonable time for working activities for leakage reduction.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.1383-1388
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• 2004

The flow characteristics in the blade passage of a low speed axial flow fan have been investigated by experimental analysis using a rotating hot-wire sensor for design and off-design operating conditions. The results show that the tip leakage vortex is moved upstream when flow rate is decreased, thus disturbing the formation of wake flow near the rotor tip. The tip leakage vortex interfaces with blade pressure surface, and results in high velocity fluctuation near the pressure surface. From the relative velocity distributions near the rotor tip, large axial velocity decay is observed at near stall condition, which results in large blockage compared to that at the design condition. Througout the flow measurements using a quasi-orthogonal measuring points to the tip leakage vortex, it is noted that the radial position of the tip leakage vortex is distributed between 94 and 96 percent span for all flow conditions. High spectrum density due to the large fluctuation of the tip leakage vortex is observed near the blade suction surface below the frequency of 1000 Hz at near stall condition.

• Restorative Dentistry and Endodontics
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• 제16권2호
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• pp.118-125
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• 1991

Eighty - eight recently extracted teeth were used to evaluate the leakage characteristics of the following retrofilling materials; amalgam, zinc oxide eugenol cement, glass - ionomer cement, and cermet glass - ionomer cement. Root canals were prepared with step - back method and obturated with gutta percha and zinc oxide eugenol sealer. Root apex were resected 2 mm from apex and class I cavities were prepared with 2 mm or 4 mm depth. The cavities were filled with above materials. After application of varnish on all surface except resected surface, the roots were placed in 1 % methylene blue solution for 6 days. After longitudinal polishing to expose cental parts of filled materials, penetrated depths of dye were measured. The results were as follws. 1. As retrofilling material, glass ionomer cement filling groups showed less leakage than the other groups except zinc oxide eugenol cement filling group(p<0.01). 2. Amalgam filling groups had greater leakage than zinc oxide eugenol cement filling group(p<0.01). 3. 4 mm depth of retrofilled cavity had no effect on leakage characteristics compared with 2 mm depth cavity(p>0.05). 4. Glass ionomer cement and cermet glass ionomer cement filling groups showed less apical leakage than amalgam filling groups. But there was no statistical significance(p>0.05). 5. There was no difference in apical leakage between glass ionomer cement filling groups and cermet glass ionomer cement filling groups(p>0.05).

• 한국전기전자재료학회논문지
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• 제30권12호
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• pp.817-821
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• 2017

As a ZnO varistor is subjected to electrical and environmental stresses, it degrades gradually, which may result in power interruption by short circuit. This study investigates changes in the electrical characteristics of ZnO varistors due to deterioration owing to energy absorption, and determines the optimal parameters for on-line diagnosis of the varistor. Two types of varistors were used for an accelerated aging experiment involving the application of the $8/20{\mu}s$ standard lightning impulse current. The electrical characteristics in terms of the reference voltage, total leakage current, resistive leakage current, and third-harmonic component of the total leakage current were measured, and their change rates were analyzed. The results revealed that the total leakage current increased slightly with an increase in the varistor absorbed energy, while the resistive leakage current and the third-harmonic component increased apparently. Therefore, the third-harmonic component of the total leakage current was proposed as the optimal parameter for on-line monitoring of ZnO varistor conditions.

• 한국신뢰성학회지:신뢰성응용연구
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• 제14권4호
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• pp.230-235
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• 2014

The failure modes of pneumatic directional control valves include leakage, wear of the spool seal, and sticking of the spool. Among them, the main failure mode of the valve is leakage. The leakage is caused by the wear of the spool seal. However, due to the characteristics of the seal material, the leakage rate is fluctuated a lot rather than constantly increased over time. If life analysis is performed using the first time data of leakage failure, predicted life cycles can be different from the real life cycles. This paper predicts life cycles of the pilot pneumatic directional control valve based on the three point moving average which considers the average of the fluctuating leakage rate.

• Tribology and Lubricants
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• 제20권4호
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• pp.183-189
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• 2004

The floating ring seal is used in an oxidizer and a fuel pump of the turbo pump unit in the liquid rocket engine to optimize a leakage without rubbing phenomenon. The damper floating ring seal, one of the floating ring seals, is with round hole pattern surfaces. It can reduce the leakage by increased friction factor that obtained from experimental data. In this paper, the leakage test about floating ring seal and damper floating ring seal was conducted. The test result showed the leakage performance of damper floating ring seal was better than the leakage performance of floating ring seal. With the leakage test the lock-up and rotation test about seal was conducted and that position is measured. The relatively large lock-up eccentric ratio was obtained from the test result of damping floating ring seal. The attitude angle of seal increases with increasing of shaft rotation.