• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.146-153
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• 2003

본 논문은 열차 곡선부 노선에서 발생하는 진동크기의 예측을 위한 것으로, 곡선부를 주행하는 틸팅 차량에 의해 발생하는 진동크기를 수치해석적으로 예측한 결과이다. 곡선부를 주행하는 틸팅차량에 의한 진동의 특징으로, 진동의 방향성분을 들 수 있다. 진동의 방향성분은 직선 구간에서는 수직성분이 월등히 우세하나, 곡선구간에서는 수평성분이 크게 증가한다. 틸팅차량의 경우, 일반열차에 비해 곡선 구간에서의 높은 속도로 인해 수평성분이 크게 발생한다 따라서 틸팅차량의 주행에 의한 인근 지역에서의 진동환경을 파악하기 위해서는 수직성분 뿐 아니라 수평성분의 정확한 파악도 필요하다. 이러한 진동의 방향성분은 근거리 또는 원거리 영역에 파라 달라져, 이의 파악을 위한 연구가 필요하다.

• Tunnel and Underground Space
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• v.4 no.1
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• pp.38-46
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• 1994

This paper concerns the design of blasts adjacent to structures and facilities. In order to investigate the site characteristics, measurements of in-situ wave propagation and laboratory tests of rock cores taken from the boreholes were carried out. Effects of rock media and delay intervals on ground vibration levels were identified from over sixty measurements of three times of test blasts. For practical use in the field, an empirical propagation equation was derived so as to reflect the characteristics of rock media and delay effects. Safe limits of vibration level for structures were conservatively established based on various suggested criteria. Safe limits for facilities were adopted so that vibration levels induced by blasting should not exceed the allowable limits specified in the manufacturer's installation condition. Suggested were blast pattern and operation to enhance the rock fracturing and to reduce the ground vibration levels under the restricted conditions.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2005.10a
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• pp.375-380
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• 2005

In Korea, most landslides are occurred during the rainy season from June to September and have a shallow failure plane parallel to the slope. For these types of rainfall-induced failures, the most important factors triggering slope unstability is not the increase of pore water pressure but the decrease of the matric suction of unsaturated soils by rainfall infiltration. So it is essential to landslide hazard assessment that defines the characteristics of infiltration in natural slopes. In this study, field measurements have been carried out in order to monitor in-situ volumetric water contents and ground water table, at several depths and locations on a natural slope. The results show that rainfall infiltration is correlated with antecedent water contents, rainfall intensity and total rainfall. The ground water table was varied sensitively by every rainfall event.

• Proceedings of the Korean Geotechical Society Conference
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• 1995.10a
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• pp.1031-1040
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• 1995

Recently, a more strict regulation has become effective on ground vibration and noise induced by construction activities. Consequently the demand for the most widely used method of installing precast piles, i.e. driven piles, is declining. At the same time the demand for low noise and low vibration piling method increased sharply. Currently there are several different low noise and low vibration methods of installing precast piles, mostly preboring method. However, the actual level of ground vibration and noise of these method of construction has not yet been clearly understood. In this paper, through field measurement, suggestion has been made to meet the requirements of the revised regulation.

• Proceedings of the KIEE Conference
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• 1997.07e
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• pp.1718-1720
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• 1997

This paper deals with n rise in electric potential of telecommunication line for electric power system by lightning surges. When $1.2/50{\mu}s$ and $8/20{\mu}s$ impulse voltage and current were applied on telecommunication cable, the voltage waveforms at the end terminal and equipment were measured. The telecommunication lines, which consist of 60 conductors and 3.5km in length, have some surge protectors such as preposition lightning arrester and TVSS. In each case, the rise in electric potential was measured for differential mode and common mode, respectively. Also, the rise in ground potential and the induced voltages were measured and analyzed. As a result, a significant rise in ground potential was observed for lightning surge. It can cause failure or malfunction of telecommunication systems.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1999.10a
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• pp.233-240
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• 1999

A general procedure is presented here to develope seismic design and analysis method for cable-supported bridges like suspension bridges subjected to ground motion. For representing a numerical model of suspension bridges. a new approach which satisfy design conditions for the initial equilibrium state of suspension bridges. without any nonlinear iterations. is proposed. The dynamic behavior of that model is verified by free vibration analysis. This study uses the response spectrum analysis to determine the Peak response of a suspension bridge to earthquake-induced ground motion. The SRSS(Square Root of Sum of Square). modal combination rule, is adopted for each direction, longitudinal and transverse. To illustrate the potential applicability for the seismic design of suspension bridges, a numerical example is presented in which the dynamic response of the Nam-hae suspension bridge subjected to earthquake

• Proceedings of the KSR Conference
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• 2004.10a
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• pp.1193-1198
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• 2004

This paper describes the lightning protection system for railway signaling equipments installed at subway car depots in Seoul metropolitan Rapid Transit Cooperation. Several measures for improving lightning protection performance are adopted; newly organized grounding system for neutral line of power system, rolling method to minimize damages induced by direct lightning strike, new measures to reduce voltage differences between the signaling equipments and the ground, and improvement of grounding system. The proposed system has greatly reduced the grounding resistance and also the voltage difference between the signaling equipments and the ground, and has prevented the accident related with lightning surges since it was installed. The proposed approach can be viewed as a useful alternative of dealing with lightning protection for railway signaling equipments.

• Journal of the Korea Institute of Military Science and Technology
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• v.13 no.6
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• pp.1172-1179
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• 2010

Since HEMP has the very short rising time and propagates widespreadly with several tens of kV/m, it threatens most of systems in its cover range. Therefore, it is important to research coupling mechanism into systems and establish countermeasures for the HEMP to protect systems effectively. This paper analyzed characteristics and trends of currents to be induced at the load of a line which is located over ground with different conditions such as polarization, incidence angle, line length and height etc. We applied double exponential waveform as the HEMP shape and used BLT method to analyze the coupling route into the line. Also, we compared the simulation data of chain matrix modeling to verify reliability of BLT modeling. In the result, two data is almost agreed.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.436-439
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• 1999

This paper present a study on the interference levels on the communication lines, which are parallel to the electrified rails. The interference study is carried out using a circuit model approach. First, the self and shunt impedances of all the conductors in the rail system and the mutual impedances between different conductors are computed. Several different scenarios are analyzed, including the load condition and a few fault conditions with different fault locations. The induced potentials on the communication cables are computed. The effect of the buried ground wires is also analyzed by comparing the results with and without the presence of the ground wires. The results presented in the paper can be used as a reference for estimating interference levels in similar rail systems.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.468-470
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• 1999

Using the EMTP(Electro Magnetic Transient Program) for the analysis of lightning direct voltage on the railway system, the shielding effects of overhead grounding wire on the railway were studied quantitatively. Installation of overhead ground wire and sap-type arrester such as s-horn provides a 6.6kV HV distribution line with goof protection effects. Even severe lightning induced voltage were create, 6.6kV HV lines can be withstand.