• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.274-275
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• 2011

Fault current problems is considered a serious issue in the power system because large fault currents not only cause many side effects to the equipments of power system but also lead to severe problems, such as blackouts. This paper deals with the structural analysis and 3-phase fault current stability of the future Seoul metropolitan power system. The simulation composition and analysis are performed with the 4th KEPCO power supply planning data using PSS/e. Through the results of the simulations, it can be observed that the future Seoul metropolitan system results in a fault current which exceeds the circuit breaker (CB) rate. This unremovable fault current can cause critical damage to power system. To resolve the problem, the algorithm for the application of Voltage Sourced Converter Back-to-Back High Voltage Direct Current (VSC BTB HVDC) is being proposed. where the most suitable location for solving fault current problem in Seoul metropolitan area is being implemented.

• Journal of the Korean Geophysical Society
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• v.9 no.3
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• pp.219-230
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• 2006

Since the key issue that 'the Yangsan fault is seismically an active fault" was raised in 1983, thegeological and geomorphological studies of active fault have been made by many researchers. These studies are mainly focused on the Yangsan fault system(YFS) and Ulsan fault system(UFS) due to many historical earthquakes occurred in this area. There are two different types of active faultings under the ENE-WSW horizontal stress field in the southeastern part of the Korean Peninsula. The NNE-trending YFS is the most prominent right-lateral strike-slip fault and has a continuous trace about 200 km long. Some part of this system has been active during the late Quaternary with evidences clearly recognized on both the northern (Yugyeri and Tosung-ri areas) and southern parts (Eonyang to Tongdosa area) of the YFS. in the southern part, the estimated vertical slip rate is about 0.02 - 0.07 mm/yr, and the lateral slip rate may be several times larger than the vertical rate. The most recent event occurred prior to deposition of Holocene alluvium, in the northern part, the fault trend locally changes to almost N-S, dips to the east and has reverse movement. The average vertical slip rate is estimated to be less than 0.1 mm/yr. The most recent event probably occurred after 1314 years BP (AD 536). The NNW-SSE (or N-S) trending UFS is a predominantly reverse fault that built up U-ie eastern mountain and has been active during U-ie late Quaternary. The fault trace is not straight but irregularly undulates along the foot of the mountain on the east. From the disturbed terraces along U-ie fault, the average vertical slip rate on U-iis system is estimated to be about 0.08.13mm/yr. The latest event is not well studied, but seems to have occurred after the last glacial maximum in the Malbang fault and 14,000 years BP in the Kalgok fault of the UFS. However, important issues such as fault segmentation, recurrence interval, age of Quaternary deposits need further studies.

• Nuclear Engineering and Technology
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• v.37 no.3
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• pp.259-264
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• 2005

This paper presents a vital area identification (VAI) method based on the current fault tree analysis (FTA) and probabilistic safety assessment (PSA) techniques for the physical protection of nuclear power plants. A structured framework of a top event prevention set analysis (TEPA) application to the VAI of nuclear power plants is also delineated. One of the important processes for physical protection in a nuclear power plant is VAI that is a process for identifying areas containing nuclear materials, structures, systems or components (SSCs) to be protected from sabotage, which could directly or indirectly lead to core damage and unacceptable radiological consequences. A software VIP (Vital area Identification Package based on the PSA method) is being developed by KAERI for the VAI of nuclear power plants. Furthermore, the KAERI fault tree solver FTREX (Fault Tree Reliability Evaluation eXpert) is specialized for the VIP to generate the candidates of the vital areas. FTREX can generate numerous MCSs for a huge fault tree with the lowest truncation limit and all possible prevention sets.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.39-52
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• 2002

Research Direction The significant research direction in mechanical fault diagnosis area: Theorles and approaches for fault feature extracting and fault classification. Identification Complicated fault generating mechanism and its model Intelligent fault diagnosis system (including the expert system and network based remote diagnosis system) One of the Key Points： Fault feature extracting techniques based on (modern) signal processing(omitted)

• Journal of the Earthquake Engineering Society of Korea
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• v.27 no.3
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• pp.157-162
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• 2023

As a result of active geological investigation of faults in Korea, many Quaternary faults have been identified and some of them were judged to have potential to generate earthquakes. Those faults need to be considered as additional seismic sources in the seismic hazard analysis. When a fault is introduced as a new source, the earthquakes generated by the fault should be removed from the area sources that include any part of the fault, to avoid double counting. In practice, however, double counting cannot completely be avoided as the complete separation of the fault-generated earthquakes from the area sources is impossible due to uncertainties related to the earthquake location, subsurface structures of faults, etc. When a new fault source is introduced, the only constraint is the invariance of earthquake frequency. The maximum earthquake and the Richter-b value should also be subject to change, but there are no competent approaches to estimate the change due to incomplete separation of earthquakes. To gain insight into the effect of a new fault source, an example calculation of the seismic hazard were carried out. The example calculation shows that addition of a new fault source centers seismic hazard around the fault source.

• Journal of The Geomorphological Association of Korea
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• v.26 no.1
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• pp.79-91
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• 2019

This study analyzed the distribution of fluvial landforms, fault-related geomorphic features and lineaments around the area of Ungchon-Ungsang in the Dongrae Fault, and discusses the charateristics of geomorphic development based on those. As a result, the NE-SW lineaments are predominantly developed in many numbers within the study area, and the NW-SE or N-S secondary lineaments are developed induced by multiple deformation with the Yangsan Fault. Geomorphologically, the early tectonic history of the Ungchon-Ungsang basin is largely divided into three stages ; 1) the Tertiary fault activity and formation of fracture zone, 2) development of erosional basin, 3) local crustal movements and development of fault-related topography. It is assumed that alluvial fans, deflected channel and stream piracy were formed by local tectonic movements related to faultings during the Quaternary.

• Journal of the Korean earth science society
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• v.26 no.5
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• pp.436-442
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• 2005

We have performed multiple geophysical surveys comprised of gravity, magnetic and resistivity methods at the Yangsan fault zone which runs through the Eonyang area, the eastern part of Kyeongsang in southeast Korea. The gravity and magnetic data provide information about geological structures. Furthermore, sections of electrical resistivity show the sharp contrast of electrical resistivity distribution across the fault zone. Since the fractured zone tends to be more conductive than fresh host rocks, the electrical resistivity survey is effective in determining the detailed structure of the fault zone. We have made gravity measurements at a total of 71 points alongside two profiles across the fault zone, and carried out an electrical resistivity survey with a dipole-dipole array at the same location using 40m dipole length. In addition, we have analyzed the aeromagnetic data on the corresponding area. The multiple geophysical properties appear to be abruptly changed in electrical resistivity, gravity and aeromagneticclearly show the different appearance across the fault zone. The fault is identified by its sub vertical attitude which is well known in the Yangsan fault zone. We have also confirmed that the magnitude of the response of the fault is much larger in the southern part of the survey area than the northern area. These results most likely to provide basic information for the further studies about the physical properties and the structures at the Yangsan fault.

• JSTS:Journal of Semiconductor Technology and Science
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• v.11 no.4
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• pp.318-328
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• 2011

Stage-level reconfigurable chip multiprocessor (CMP) aims to achieve highly reliable and fault tolerant computing by using interwoven pipeline stages and on-chip interconnect for communicating with each other. The existing crossbar-switch based stage-level reconfigurable CMPs offer high reliability at the cost of significant area/power overheads. These overheads make realizing large CMPs prohibitive due to the area and power consumed by heavy interconnection networks. On other hand, area/power-efficient architectures offer less reliability and inefficient stage-level resource utilization. In this paper, I propose a hierarchical multiplexing interconnection structure in lieu of crossbar interconnect to design area/power-efficient stage-level reconfigurable CMP. The proposed approach is able to keep the reliability offered by the crossbar-switch while reducing the area and power overheads. Experimental results show that the proposed approach reduces area by up to 21% and power by up to 32% when compared with the crossbar-switch based interconnection network.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.729-739
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• 2015

An algorithm for fault detection and classification method for wide-area protection in Korean transmission systems is proposed. The modeling of 345-kV and 765-kV Korean power system transmission networks using the Electro Magnetic Transient Program - Restructured Version (EMTP-RV) is presented and the algorithm for fault detection and classification in transmission lines is developed. The proposed algorithm uses the Wavelet Transform (WT) and Singular Value Decomposition (SVD). The Singular value of Approximation coefficient (SA) and part Sum of Detail coefficient (SD) are introduced. The characteristics of the SA and SD at the fault conditions are analyzed and used in the algorithm for fault detection and classification. The validation of the proposed algorithm is verified by various simulation results.

• Economic and Environmental Geology
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• v.21 no.2
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• pp.131-137
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• 1988

Geological and electrical resistivity surveys were carried out to investigate subsurface geology and geologic structure of the Bonghwajae area in the Okchon zone. Pseudosections of the apparent electrical resistivity distribution along the three survey lines were obtained by using dipole-dipole electrode array method, and models of subsurface geology and geologic structure by using two dimensional finite difference method. The Bonghwajae fault zone exists around Bonghwajae area in the north-south direction, and is a boundary between Okchon Group and Choson Supper Group. Metabasite and hornblende gabbro intruded along the Bonghwajae fault zone remaining two fracture zones with low resistivity value of 20 ohm-m and widths of about 100m and 70-300m. They strike nearly N-S and dip westward with a high angle of $60-70^{\circ}$. Sochangri fault with a width of about 160m exists between Jisogori and Bonghwajae, by which Bonghwajae fault zone is displaced about 1km in the east-west direction. Hornblende gabbro whose electrical resistivity value is in the range of 5000-8000 ohm-m intruded the metabasite of 2000-4500 ohm-m after the Sochangri fault had formed. Great Limestone Group is widely distributed in the east of Bonghwajae fault zone, and interbeds so called Yongam formation of graphitic black slate with an extremely low electrical resistivity value of 2 ohm-m.