• 전기학회논문지
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• 제56권3호
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• pp.472-480
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• 2007

This paper analyzes overvoltage on testing line for various parameter effect examination. Model systems consist of overhead line and underground cable. The model considered actual characteristic data of distribution lines. and will be constructed at testing yard. The simulations were performed under various line configuration such as cable kinds, cable length, lightning wave, lightning wave time, transformer and branch circuits. The simulation models are established by EMTP/ATPDraw and Line Constants are calculated by ATP_LCC. When lightning surge strikes on conductor of overhead line, EMTP/ATPDraw calculates overvoltage in many cases. Simulation results will be compared with real testing results at testing yard. The compared results will be used to establish protection methods in actual underground distribution systems.

• 조명전기설비학회논문지
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• 제22권4호
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• pp.130-138
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• 2008

뇌서지 전압이 전파되는 양상은 대상 전원계통과 기기별로 차이를 보인다. 하지만 뇌서지가 유입되는 대상기기를 중심으로 보면 뇌서지 침입경로는 전원선의 두 선간, 전원선과 대지간, 전원선과 PE도체, 중성선과 대지 간 등으로 구분되어진다. 또한 통신기기에서 전원측에서 들어오는 뇌서지 외에 통신선의 선간, 통신선과 대지 간으로 입사하는 경로가 존재한다. 이 논문은 각각의 경로를 통하여 대상기기에 침입하는 뇌서지에 대해 SPD를 사용한 전원계통의 안전향상 기법 중 독립접지, 공통접지, 바이패스 어레스터를 이용한 접지의 뇌서지 양상을 실증실험을 통하여 분석한 결과를 기술하고 있다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2004년도 춘계학술대회 논문집
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• pp.141-148
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• 2004

In this paper, we have investigated the inductive voltages, currents, frequencies of output line of electrodeless fluorescent lamp system as an surge is supplied and have analyzed the surge characteristics as an phase alteration of input voltage with an surge suppling. A result os measurement is that the inductive over-voltages(H-PE, N-PE) on output line of electrodeles fluorescent lamp system showed more high than inductive overvoltages of H(hot)-N(neutral) line. Therefore, designer of system will lay emphasis on an protective circuit with considening an overvoltage(H-PE, N-PE) or phase of input voltage.

• 대한기계학회논문집B
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• 제21권5호
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• pp.670-678
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• 1997

A method to mitigate the thermal stratification phenomenon of pressurizer surge line is proposed by heating bottom outside of horizontal pipe. Unsteady two dimensional model has been used to numerically investigate an effect of heating the bottom of pipe. The dimensionless governing equations are solved by using the control volume formulation and SIMPLE algorithm. Temperature and streamline profiles of fluids and pipe walls with time are compared with the previous study result. The numerical result of this study shows that the outside heating can relaxate the thermal stratification flow of the pressurizer surge line. Maximum dimensionless temperature difference between hot and cold sections of the pipe inner wall which causes thermal stratification was reduced from 0.514 to 0.424 at dimensionless time 1, 632 and 1, 500 respectively.

• 대한전기학회논문지:전력기술부문A
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• 제53권4호
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• pp.238-247
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• 2004

This paper describes the insulation coordination scheme of line in distribution system when the direct lightning surge strikes. The BIL that is applied to distribution system is not properly considered the performance and operation of arresters. Because of that, the high BIL is being used at partial system. This paper variously analyses the lightning overvoltage of line and equipment with earth of overhead grounding wire and installation types of arrester. From these result. authors examine the rationality of BIL.

• 한국공작기계학회논문집
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• 제12권3호
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• pp.38-44
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• 2003

The solenoid valve in ABS hydraulic modulator is a two directional on-off valve and is controlled by around 100Hz high speed pulse width modulation. When the valve is switched from open state to closed state, noise and vibration due to pressure surge phenomena in the hydraulic line and wheel cylinder are made. In this study, we identify Pressure surge phenomenon in the braking process of a ABS, and investigate the way to reduce the phenomenon. For the purpose of theoretical analysis on the pressure surge in the closed state hydraulic line, characteristic curve method based on wave equation was utilized. To reduce the surge, high frequency control of 20kHz was attempted. The result showed that the surge pressure of 50% was reduced compared to one observed in the low frequency control. Duty variation of high frequency can control current of solenoid valve and prevent sudden change of displacement.

• 한국전자파학회지:전자파기술
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• 제6권4호
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• pp.57-61
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• 1995

일반적으로 서지발생기의 출력은 전원선을 통하여 피시험기에 전달된다. 이 논문에서는 전원선의 길이에 따라 전달되는 서지의 감쇄량을 이론적, 실험적으로 조사하였다. 서지출력은 전원선에 의해 비례적으로 감쇄되어 40m 전원선을 사용할 경우에 77%의 서지에너지만이 피시험기에 전달되었다.

• 대한전기학회논문지:전력기술부문A
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• 제55권8호
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• pp.313-321
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• 2006

This paper describes the overvoltage obtained by surge behavior analysis in testing underground distribution systems. Model systems consist of overhead distribution line and underground cable. Such model system considered various characteristics of actual distribution systems will be soon constructed at testing yard. Simulation is carried out under various states such as cable kinds, cable length, lightning wave and time, and branch circuits. Model is established by EMTP/ATPDraw. Line Constants are calculated by ATP_LCC. When the direct lightning surge strikes on conductor of overhead line, the overvoltage is calculated using EMTP/ATPDraw in many cases. Simulation results will be compared with real testing results at testing yard in the near future. The compared results will be used to establish protection methods in actual underground distribution systems.

• 한국유체기계학회 논문집
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• 제8권6호
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• pp.7-14
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• 2005

The waterhammer occur when the pumps are started or stopped for the operation or tripped due to the power failure, and the hydraulic transients take place as a result of the sudden change in velocity. Several times, the field tests of the waterhammer were carried out for Pangyo booster pumping station. Pangyo pumping station was installed with the booster pumps of 6 sets and the in-line pumps of 2 sets. The in-line pumps are additionally needed to the surge suppression device so that the pumping station acquire the safety and reliability for the pressure surge.

• 한국압력기기공학회 논문집
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• 제11권1호
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• pp.45-52
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• 2015

Even though a lot of efforts have been devoted to evaluate welding residual stress characteristics of nuclear components, from the view point of accuracy, there are still some arguments in application of engineering estimation schemes. In this paper, three-dimensional finite element analyses (FEA) were carried out to predict residual stress distributions in butt welds of a typical surge line piping. Mesh optimization was conducted and subsequent analysis results such as the axial and hoop stress components along the weld center line and inner wall. Moreover, alternative evaluation was conducted by using three representative equations and their results were compared to those of FEA. Thereby, key parameters affecting to temperature profiles and residual stress distributions were derived as well as an optimum engineering estimation scheme was recommended.