• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 하계학술대회 논문집 A
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• pp.293-295
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• 2003

KEPCO's high voltage distribution power line laid under the ground near to the J-booster pumping station that supply water for living. Lightening rod equipment does not installed at the J-booster pumping station because KEPCO's over head ground wire for protection functions as a lightening rod equipment. In this study, it is concerned whether KEPCO's over head ground wire for protect the distribution power line affect to the J-booster pumping station which is installed for reduce the damage from the direct and indirect lightening. If KEPCO's protection area does not affect to the J-pumping station, it is plan to examine the construction method of lightening rod protection angle and lightening rod equipment and to suggest the optimum protection plan using the surrounding structure based on the suitability of protection area.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 추계학술대회 논문집
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• pp.1203-1208
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• 2007

In the past decades, complain about ground vibration and noise induced by pile driving has been quickly increased. Because of that, auger drilled piling methods have frequently used specially in urban area. However, the present auger drilled piling methods induce inevitable ground disturbance as well as a certain degree of vibration and noise due to the final hammering. For these reasons, a new auger drilled piling method is required to be developed. This paper introduces PDT(Pulse Discharge Technology) piling method and presents the characteristics of bearing capacity. The PDT piling method is to install in-situ piles using electric power so called Pulse. The pile installed by PDT appears to be able to develop shaft and end bearing capacity efficiently. This paper introduces PDT(Pulse Discharge Technology) piling method, which is the 512nd new construction technology. The PDT piling method is to install in-situ piles using electrical power so called Pulse power. The pulse power is physical value that indicates the energy change per unit time(dE/dt). Since the pulse power is to push ground, using the pulse power is enable a hole to be expanded as well as the ground to be improved by compaction. Therefore, The pile installed by PDT appears to be able to develop shaft and end bearing capacity efficiently. In this study, couples of pile loading tests were carried out to figure out whether or not the PDT piling method is applicable to constructions like rail road facility. As a result, it was concluded that the PDT piling technique meet the requirements for such a rail road related construction.

• Journal of Power Electronics
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• 제18권2호
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• pp.343-355
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• 2018

A wide-voltage-conversion range bidirectional DC-DC converter is proposed in this paper. The topology is comprised of one typical LC energy storage component and a special common grounded asymmetric H-bridge with four active power switches/anti-parallel diodes. The narrow output PWM voltage is generated from the voltage difference between two normal (wider) output PWM voltages from the asymmetric H-bridge with duty cycles close to 0.5. The equivalent switching frequency of the output PWM voltage is double the actual switching frequency, and a wide step-down/step-up ratio range is achieved. A 300W prototype has been constructed to validate the feasibility and effectiveness of the proposed bidirectional converter between the variable low voltage side (24V~48V) and the constant high voltage side (200V). The slave active power switches allow ZVS turn-on and turn-off without requiring any extra hardware. The maximum conversion efficiency is 94.7% in the step-down mode and 93.5% in the step-up mode. Therefore, the proposed bidirectional topology with a common ground is suitable for energy storage systems such as renewable power generation systems and electric vehicles with a hybrid energy source.

• Nuclear Engineering and Technology
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• 제50권6호
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• pp.860-868
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• 2018

This article presents a new design of earthquake instrumentation that is suitable for quick decision-making after the seismic event at the nuclear power plant (NPP). The main objective of this work is to ensure more availability of the NPP by expediting walk-down period when the seismic wave is incident. In general, the decision-making to restart the NPP after the seismic event requires more than 1 month if an earthquake exceeds operating basis earthquake level. It affects to the plant availability significantly. Unnecessary shutdown can be skipped through quick assessments of operating basis earthquake, safe shutdown earthquake events, and damage status to structure, system, and components. Multidecision parameters such as cumulative absolute velocity, peak ground acceleration, Modified Mercalli Intensity Scale, floor response spectrum, and cumulative fatigue are discussed. The implementation scope on the field-programmable gate array platform of this work is limited to cumulative absolute velocity, peak ground acceleration, and Modified Mercalli Intensity. It can ensure better availability of the plant through integrated decision-making process by automatic assessment of NPP structure, system, and components.

• Nuclear Engineering and Technology
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• 제46권5호
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• pp.699-706
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• 2014

The probabilistic seismic performance of a standard Korean nuclear power plant (NPP) with an idealized isolation is investigated in the present work. A probabilistic seismic hazard analysis (PSHA) of the Wolsong site on the Korean peninsula is performed by considering peak ground acceleration (PGA) as an earthquake intensity measure. A procedure is reported on the categorization and selection of two sets of ground motions of the Tohoku earthquake, i.e. long-period and common as Set A and Set B respectively, for the nonlinear time history response analysis of the base-isolated NPP. Limit state values as multiples of the displacement responses of the NPP base isolation are considered for the fragility estimation. The seismic risk of the NPP is further assessed by incorporation of the rate of frequency exceedance and conditional failure probability curves. Furthermore, this framework attempts to show the unacceptable performance of the isolated NPP in terms of the probabilistic distribution and annual probability of limit states. The comparative results for long and common ground motions are discussed to contribute to the future safety of nuclear facilities against drastic events like Tohoku.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2000년도 춘계 학술발표회 논문집 Proceedings of EESK Conference-Spring
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• pp.97-104
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• 2000

Evaluating a Review-Level Ground Motion is a key to efficiently perform Seismic Margin Assessment of nuclear power plants whose purpose is to determine a ground motion level for which a plant has high-confidence-of-a-low-probability of seismic-induced core damage and to identify any weaker-link components. In this study a method to obtain RLGMs is reviewed which is recommended by Electric Power Research Institute and implemented to be applied to Limerick site in eastern and central U. S as a case study. This method provides reasonable and site-specific RLGMs as minimum required plant HCLPF for SMA that meet a target mean seismic core-damage frequency based on seismic hazard results and generic values of uncertainty and randomness parameters of the core-damage fragility curves. In addition high-frequency RLGM is justifiably modified to reflect the increased seismic capacity of high-frequency components and spatial variation and incoherence of input ground motion on a basemat of large structures by establishing a method to obtain high0-frequency reduction factors according to EPRI guidelines.

• 전기학회논문지
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• 제56권6호
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• pp.993-999
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• 2007

This paper discusses the effects of CD type superconducting cable operation in 22.9kV multi neutral grounded distribution system during L-G fault and counterplans to power system protection. In case of using the 3-phase CD-type superconducting cable, the inductance of superconducting cable system would be decreased due to the current of shield part of superconducting cable, which is opposite direction and nearly equal value with respect to main superconductor. However, when the shield circuit system is operated in shorted state, shield current decreases faulted ground current and give effects to power system protection scheme. This study examines the phenomena of single line to ground fault case in above mentioned system using the EMTDC program and discusses the right operation method of superconducting shield.

• 조명전기설비학회논문지
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• 제29권6호
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• pp.58-62
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• 2015

When an emergency generator is running, it supplies the power for critical loads. Generator protection requires the consideration of many abnormal conditions that may occur with generators include overvoltages and ground faults. Modern day power systems create harmonics within the electrical network that can have an impact upon the associated protective system. This paper focuses on the analysing of the cause and development of a solution for the malfunction of induction disc type overcurrent ground relay by generation of harmonics during emergency generator operation.

• 조명전기설비학회논문지
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• 제15권3호
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• pp.91-96
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• 2001

본 논문은 전기철도시스템 고압 배전선로에서 직격뇌에 의한 가공지선의 영향에 대해서 설명하였다. EMTP를 사용하여 가공지선과 보안기의 영향을 정량적으로 분석하였다. 또한 전차선로의 구조변경과 피격전류의 크기, 파미값의 변화에 대한 영향도 평가하였다. 분석결과 기존 시스템에 가공지선의 설치는 전기철도시스템 고압 배전선로에 유도되는 피격전압을 억제하는 효과가 있음을 입증하였다.

• 한국조명전기설비학회:학술대회논문집
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• 한국조명전기설비학회 2006년도 춘계학술대회 논문집
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• pp.157-159
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• 2006

The advantages of LED(Light Emitting Diode) are low electric power consumption, long life time and excellent visibility. And a LED light source does not include the mercury(Hg) and or a filament, it is expected as an environmentally friendly next generation light source with its good reliability. In order to design and develope the flash lantern using LED for aironautical ground lights, technical trends and new standards about the aironautical ground lights were inspected, and power consumption and flash time for effective luminous intensity of aironautical ground lights were analyzed.