• Electronics and Telecommunications Trends
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• v.5 no.4
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• pp.12-41
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• 1990

본고는 자연적인 현상의 번개와 같은 서어지로 인해 야기되는 각종 위해(Harm)로부터 전기통신회선을 보호하기 위해, 세계 각국에서 규정하고 있는 서어지 기술기준의 동향을 분석하여 우리나라가 대처해 나가야 할 방향을 찾고자 한 것이다.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.2 no.2
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• pp.91-97
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• 1991

낙뢰 현상은 오랫동안 인류에게 신의 분노와 같은 것으로 여기며 신비스럽고 두려운 자연현상 중의 하나로 생각했으나, 자연과학의 발달로 요즈음은 대기중의 전기방전으로 자연스럽게 받아들인다. 그러나 최근 문제가 되고 있는 EMI/EMC 관점에서 보면 낙뢰 현상은 EMI를 일으키는 대표적인 발생원으로서 여전히 두려움 의 대상이다. 본 기술 해설난에서는 먼저 낙뢰시 발생되는 전자파의 세기와 파형에 대해 살펴보고, 이러한 전자파에 의한 EMI 문제 사례로서 전화가입자 선로에 유기되는 낙뢰서어지로 부터 교환기 보호라는 관점에 관해 기술하기로 한다.

• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.1
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• pp.15-24
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• 1986

Pressure trasients must deal with safety problem of system. For identification of physical situation that can and method of limiting surges are essential consideration in sucessful design. The finite difference equation by method of characteristics are derived from the governing equation of unsteady flow in a pipe, and solved by using boundary condition derived. A computer program which can simulate general hydraulic system is developed by using finite difference equations and boundary conditions derived. The sumulated resulted by developed computer program are in fair agreement with experiment result.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.591-595
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• 1997

In analysis of piping vibration of petrochemical plant, the forcing functions mainly depend upon the equipment working mechanism and vibration resources in the piping systems. In general, harmonic function is used for the system with rotary equipments. Mechanical driving frequencies, wave functions, and response spectrum are used for reciprocating compressors, surge vibration of long transfer piping, and seismic/wind vibration, respectively. In this study, for the spray injection case inside the pipe, forcing function was modeled, in which two different fluids are distributed uniformly. To confirm the results, the scheme used for the forcing function was applied for real piping system. The vibration mode of the real system was consistent with the 4th mode obtained by simulation using the forcing function formulated in this study.

• Journal of the Korea Society for Simulation
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• v.10 no.4
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• pp.1-10
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• 2001

For the simulation of piping vibrations in petrochemical plants, forcing functions mainly depend upon the equipment working mechanism and vibration resources in the piping systems. In general, harmonic function is used to simulate rotary equipment. Mechanical driving frequencies, wave functions, and response spectrum are used to simulate reciprocating compressors, surge vibration of long transfer piping, and seismic/wind vibration, respectively. In this study, the general suggestions for forcing functions were reviewed and proposed the forcing function to simulate the spray injection system inside the pipe in which two different fluids are distributed uniformly. To confirm the results, the scheme was applied for a real piping system. The vibration mode of the real system was consistent with the 4th mode (26.725 Hz) obtained by simulation using the forcing function presented in this study.

• Journal of Korea Water Resources Association
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• v.31 no.6
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• pp.757-768
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• 1998

rate of outflow is equated to the total rate of flow, both the state equation and its linearized equation yield almost identical oscillations of water levels. This shows that effects of pipe resistance on the surges are small, and justifies a free oscillation analysis. Free oscillation equation has six eigen modes of different periods, including a rigid mode which is existed when the pumped rate of outflow differs from the total rate of inflow. The six modes constitute a variety of surges dependent on different inflow and outflow conditions. Presence of the rigid mode needs sophisticated pump operations adjusted to real flood inflows.