• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.562-564
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• 2004

The containment leakage rate test performed on the nuclear power plants consists of following phases : pressurizing the containment, stabilizing the atmosphere, conducting a Type A test, conducting a verification test, depressurizing the containment. It takes more than 48 hours from the pressurization to the depressurization and the prediction of the results will help to prepare the next test phase. In this paper, to predict the leakage rate, the prediction methods based on the least square method are evaluated according to the input variables and the measurement period.

• Journal of Magnetics
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• 제19권1호
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• pp.37-42
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• 2014

The equivalent model of a permanent magnet (PM) plays an important role in electromagnetic system calculation. A type of subsection model for a PM bar is established, to improve the accuracy of the traditional equivalent circuit method. The mathematical expression, and its end verification condition, are presented. Based on the analytical method and finite element method, the leakage permeance calculation of a PM bar in an open magnetic circuit is investigated. As an example, for a given certain type of PM bar, the magnetic flux of each section is validated by experiment, and by simulation. This model offers a foundation for building a high accuracy equivalent magnetic PM model in an electromagnetic system.

• Transactions on Electrical and Electronic Materials
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• 제12권2호
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• pp.43-50
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• 2011

Carbon-nanotube metal oxide semiconductor field effect transistor (CN-MOSFET) is a promising future device candidate. The electrical characteristics of 16 nm N-type CN-MOSFETs are explored in this paper. The optimum N-type CN-MOSFET device profiles with different number of tubes are identified for achieving the highest on-state to off-state current ratio ($I_{on}/I_{off}$). The influence of substrate voltage on device performance is also investigated in this paper. Tradeoffs between subthreshold leakage current and overall switch quality are evaluated with different substrate bias voltages. Technology development guidelines for achieving high-speed, low-leakage, area efficient, and manufacturable carbon nanotube integrated circuits are provided.

• 전력전자학회논문지
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• 제17권6호
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• pp.539-545
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• 2012

Due to merits cost and efficiency, the transformer-less type photovoltaic (PV) inverters have been popularized in the solar market. However, the leakage current flowing through a parasitic capacitor between PV array and ground can cause adverse effect in the transformer-less PV system. In this paper, a bi-directional PV inverter with high efficiency and low noise is proposed for the PV system with an energy storage device. The proposed inverter is a transformer-less type and performs the bi-directional power control between dc sources and grid with high efficiency. In addition, the proposed inverter can suppress the leakage current and obtain low noise characteristic. Finally, 3-kW prototype was implemented to confirm validity of the proposed inverter.

• 한국정밀공학회지
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• 제15권4호
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• pp.76-82
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• 1998

Sealing an oil-air mixture plays important roles to have an enhanced lubrication for high speed spindle. Current work is emphasized on the investigation of the air jet effect on the protective collar type labyrinth seal. To improve the sealing capability of conventional labyrinth seal, air jet is injected against through the leakage flow. It has a combined geometry of a protective collar type and an air jet type. In this study, both of a numerical analysis by CFD(Computational Fluid Dynamics) and experimental measurements are carried out to verify sealing improvement. Both of the turbulence and the compressible flow model are introduced in CFD analysis. The sealing effect of the leakage clearance and the air jet magnitude are studied for various parameter in the experiment. The results of pressure drop in the experiment match reasonably to those of the simulation by introducing a flow coefficient. Effects of sealing improvement are explained as decreasing of effective leakage clearance by air jetting. Thus, sealing effect is improved by amount of air jetting even though clearance becomes larger.

• 한국안전학회지
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• 제33권1호
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• pp.35-40
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• 2018

This research aimed to develop an leakage detector of analyzing the electric potential generated from the electric leakage of electric equipment of the fountain. To accomplish this goal, the potential gradient was analyzed against path 1 ~ path 4; this was done by taking the lighting of a fountain as the electric leakage point based on code analyses in Korea and other countries. Lighting 1 was taken as the electric leakage point, and the earthing point was set against lightings(2~3). It appeared that the allowable touch voltage against the 1 type(under 2.5 V) exceeded 60.0%. Therefore, the lighting of fountain turned out to be the most dangerous point, and electric shock could be formed by the electric leakage of electric equipment in underwater as well as by the lighting. An leakage detector was developed based on this risk; this detector is capable of analyzing the electric potential of a electric equipments of the fountain in underwater. Then, a verification test was carried out. This leakage detector can be used to measure electric potential in various submerged areas such as swimming pools, flooded spaces, and fountains.

• 대한건축학회논문집:구조계
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• 제34권9호
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• pp.19-26
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• 2018

The focus of this study was centered around 15 common injection type water leakage repair materials (3 different types for each; synthetic polymer, cementitious, acrylic, epoxy, urethane) used in concrete structures of Korea and analyzing their wet surface adhesion performance in accordance to the ISO TS 16774 Test Method for Repair Materials for Water-leakage Cracks in Underground Concrete Structures, Part 4: Test Method for Adhesion on Wet Concrete Surface, and the results of this study was taken to be place under a comparative analysis with the results of the preceeding study on response to substrate movement performance study. The results of this comparative study showed that other than 1 specimen of 1 type of the acrylic and 3 specimens of 1 type of the synthetic polymer type materials, all of the 93% of the specimens used in this study showed stable adhesion on wet substrate surface, and we were able to determine that materials that have proper response properties against substrate movement are highly flexible and have high adhesion properties, but their adhesion properties on wet substrate would change based on their viscosity.

• 한국산학기술학회논문지
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• 제22권4호
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• pp.150-159
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• 2021

본 논문에서는 충전 시 발생하는 누전차단기 Trip으로 충전 중단에 의한 전기자동차 사용자의 불편함을 방지하기 위한 것이다. 현장 사례연구로 충전기 고장(failure) 유형, 차종별 누설전류 측정실험, 누전차단기 동작 실험 시 여름철 충전기 내부 온도가 60 ℃이상까지 상승하여 누전차단기가 정격 감도 전류의 80%에서 Trip으로 충전 중단됨을 확인하였다. Joule Heating 모델링을 통하여 32A 전류를 초기 시간 t=0 (s)의 기준온도 30℃에서 통전하여 t=3000 (s)경과 후에는 누전차단기 충전부 주위에서 발열이 32.4℃까지 증가함을 시뮬레이션으로 확인하였으며, 통계 검증 tool을 활용하여 온도 및 시간(s) 요인이 발생 열량에 상관관계 0.97로 검증되었다. 본 논문의 연구 실험 결과는 충전기 기구 물 개발 시 충전케이스의 재질, 내부 배선의 배치, 유전 매질에 따른 Joule Heating 시뮬레이션 수행으로 여름철 충전기 내부 온도 상승에 의한 누전차단기 감도 전류 Trip을 방지할 수 있음을 알 수 있었다.

• Structural Engineering and Mechanics
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• 제49권3호
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• pp.311-327
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• 2014

The safety relating to leakage of water and pitch instability of ship chambers of the full balanced hoist vertical shiplifts has been the focus of adoption of the type of vertical shiplifts. This paper aims to remove the doubts through theoretical and engineering researches. The leakage and pitch stability of ship chambers of full balanced hoist vertical ship lifts are investigated on the basis of theoretical analysis and exploration of engineering measures. Regarding the issue of leakage of ship chambers, a mathematical model on leaking process is built and corresponding formula and coping measures are obtained which can be applied in control program of ship lifts by linking with monitoring. The concept of safety grade is put forward to seek the best technical and economic index and the corresponding technical measures are for different grades of ship lift is suggested. For the issue of pitch instability, a methodology of combining theoretical deduction and summary of achievements of design and operation of the type of the full balanced hoist shiplifts is adopted, and the formula for design about pitch stability of ship chambers is derived.

• 전기학회논문지
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• 제58권10호
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• pp.1942-1946
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• 2009

This paper presents a shape design process of Claw-Poles Stepping Motor(CPSM) using Modified Magnetic Equivalent Circuit Method(MMEC). Because this motor is adopted on low power devices, the motor size is a very small type. But it have a very strong permanent magnet. So magnetic saturation effect happens on yoke teeth of CPSM. Also this magnetic saturation effect causes more leakage flux component between yoke tooth have another pole. In this motor type, it is essential to design a shape of yoke teeth for avoiding the magnetic saturation effect and the leakage flux. In this paper, MMEC including the magnetic saturation effect and the leakage flux component was used for design process. Comparing with data calculated by using the MMEC and results analyzed by 3-D FEM, it could be stated that the design process with MMEC was reasonable. Finally, the model has the optimized shape of yoke teeth was compared with a conventional model for no-load Back EMF and torque at steady-state operation.