• 한국철도학회:학술대회논문집
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• 한국철도학회 2003년도 추계학술대회 논문집(II)
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• pp.579-584
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• 2003

In this study, anisotopic yield function is proposed for the numerical analysis of reinforced tunnel ground with grouting. For this, material properties of the reinforced ground both by equilibrium as well as kinematic condition along the interface and by the mean field theory of Eshelby (1957) and Zhao (1990) are compared with each other and, as a result, the advantage/disadvantage of the proposed models are summarized. Finally, reinforced ground around tunnel with grouting is analyzed numerically. A new anisotropic yield function model is shown to be more reliable than the previous one and the predicted result is agreeable with the experimental data available.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.51-58
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• 2008

The George Massey immersed tunnel passes the Fraser River near Vancouver, Western Canada. In this paper, dynamic analysis of the tunnel on sandy soils was performed using an effective stress constitutive model called UBCSAND. This model is able to calculate pore pressure rise and resulting tunnel deformation due to cyclic loading. Centrifuge tests conducted at RPI are used to verify the model performance. Centrifuge tests consist of 3 models: Model 1 is designed for an original ground condition, Model 2 for a ground improvement by compaction method, Model 3 for a ground improvement by gravel drainage. The results of centrifuge Model 1 are presented and compared with predictions of UBCSAND model. This model well captured the results of centrifuge test and therefore can be used to predict dynamic behavior of similar tunnels or underground structures on sandy soils.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2004년도 춘계학술발표회
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• pp.181-188
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• 2004

Composite soil methods among granular pile merhods that we could improve soft ground of fine soil particles by, have permeability as one of fundamental principals. The catual state, that voids of sand or gravel, etc. of granular soil as drainage materials are clogged by fine soil particles, is 'clogging'. In this study, it is analysed that using sand or gravel, etc. of granular soil as drainage materials, experiment are made by clogging tester on several condition.

• 한국지진공학회:학술대회논문집
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• 한국지진공학회 2001년도 추계 학술발표회 논문집 Proceedings of EESK Conference-Fall 2001
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• pp.83-90
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• 2001

The site effects of local geological conditions on seismic ground motion are performed using 2D numerical method. For the analysis, a numerical method far ground response analysis using FE-BE coupling method is developed. The total system is divided into two parts so called far field and near field. The far field is modeled by boundary element formulation using the multi-layered dynamic fundamental solution that satisfied radiational condition of wave. And this is coupled with near field modeled by finite elements. In order to verify the seismic response analysis, the results are compared with those of commercial code. As a result, it is shown that the developed method can be an efficient numerical method to solve the seismic response analysis of the site effect in 2D problem.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.262-271
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• 2003

Specification of reinforcement method was suggested according to the ground condition and tunnelling environment such as adjacent building and surface settlement. Tunnel database consists of 8 different groups of data according to the tunnel construction situations and major problems of ground. A tunnel countermeasure expert system based on client/server system was developed with on-line. The expert system provides proper solution to the each construction sites backing up the information of the tunnelling and ground information through Internet. The effective factors of tunnel construction were shown by the analyzing relationship and partial relationship between face stability and RMR factors. This study will be very helpful to make the most of in-situ data and suggest proper applicability of tunnel reinforcement system escaping from the dependence of some experienced experts for the absent of guide.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.1360-1361
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• 2008

This paper presents the surface potential rise distribution near grounding electrodes produced by ground fault currents. The small-scale model with the foundation pedestal in hemispherical tank was used to simulate the ground fault condition of the electrical installations for street lamps. When entering the fault current through the test ground electrode, surface potential rise, potential gradient, touch and step voltages for different grounding electrode shapes were measured, and the results obtained were discussed.

• 한국공작기계학회논문집
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• 제13권2호
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• pp.9-16
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• 2004

Because a generated heat during grinding operation makes a serious deformation on a ground surface as a convex form, a real depth of cut in deformed zone has larger than an ideal depth of cut. Consequently, the ground surface has a geometric error as a concave form after cooling the workpiece. In this study, the force and the geometric error of surface grinding were examined. From evaluating magnitude and mode of the geometric error according to grinding conditions, an optimal grinding condition was proposed to minimize the geometric error. In addiction the relationship between the geometric error and the grinding force was found out. Due to least square regression it was able to predict the geometric error by using the grinding force.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 E
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• pp.1773-1775
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• 1998

This paper deals with the pulse generator using PFN(Pulse Forming Network), and its operation characteristics and application. Two kinds of pulse generator were composed of the best appropriate condition circuit. The output current of the one pulse generator has the rise time of 28 ns and the pulse duration of $7{\mu}s$. The other pulse generator has high current of about 2kA. By use of the former generator with rapid rise time, the impulse impedance characteristic of ground electrodes was investigated with measuring the ground potential rise when the pulse current was injected into the ground electrode.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2000년도 춘계학술대회 논문집
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• pp.86-92
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• 2000

Recently, the Korea National Railways (KNR) is undertaking a program of electrification of the existing railway routes. In order to implement the ongoing plan, KNR authorized a preliminary engineering study of its electrical systems. This effort included a comprehensive analysis of new grounding networks. The new grounding system runs in parallel with the rails and is connected to all metal structures such as rails, overhead protection wires and substation grounding grids etc., creating an equipotential ground network. This paper presents a study on coupling levels that can disturb signaling and telecommunications in adoption of the new grounding network The simulation for the study is carried out using Matlab software, 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 coupling levels in similar rail systems.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 학술회의 논문집 정보 및 제어부문 B
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• pp.417-420
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• 2003

In this paper, we have designed the ground faults detection and disconnection algorithm at normal rendition of AC 120V to 240V rating voltage. Ground faults in electrical network have the characteristics of low current, 60Hz frequency to 2kHz frequency. The load rendition are no load and 20A load. The controller have the trip level are 6mA with ground faults. Conventional controller does not have the miswiring condition. The Controller algorithm using pic16c71 microprotessor.