• Journal of the Korean Society for Railway
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• v.9 no.3 s.34
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• pp.305-312
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• 2006

Gravel ballasted tracks are used as a basic structure for the domestic railway tracks. However, such kind of tracks has few disadvantages with service life of the structure, such as rapid deterioration of the tracks. Due to this reason, there is a need to develop low maintenance track to improve the service life of the conventional line tracks. CMP paved tacks are one of the kind of concrete tracks those were manufactured by using the prepacked concrete techniques. The purpose to develop paved tracks is to reduce the maintenance cost. The most important controlling factors to design the paved tracks are surrounding environmental condition and repeated train loading. In this study, in order to investigate the deformation characteristics such as displacement, earth pressure, strain ratio, and crack along the repeated loading cycle, cyclic loading test through real scale model was carried out.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.11a
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• pp.504-511
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• 2001

In this research, we developed a computer program that designs a centrifugal impeller and diffuser, and predicts the far-field noise from the impeller. To design the impeller optimally, the TEIS model, which was originally developed by Japkise(1985), and the mean-line analysis are combined to predict the performance and design the optimal impeller simultaneously. The geometric configurations are provided by a GUI software (iDesignComp). The noise from impeller can be computed by the rapid loading procedure, which generates a surface between two blades and calculates the pressure distributions on the suction and pressure sides. The steady loading noise is computed by the rotating dipole source distribution via Ffowcs Williams & Hawkings equation.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.122-129
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• 2004

Finite element analysis was performed to analyze structural safety of a new heavy-duty direct injection diesel engine. A half section of the in-line 6-cylinder engine was selected as a computational domain. A mapping method was used to project heat transfer coefficients from CFD results of engine coolant flow onto the FE model. The accurate setting of thermal boundary condition on the FE model was expected to result in improved prediction of temperature, cylinder bore distortion, and stresses. Characteristics of high cycle fatigue were investigated by assuming the engine was operated under the following five loading conditions repeatedly; assembly force, assembly force with thermal loading, alternating maximum gas pressure loading at each cylinder combined with assembly force and thermal loading. Distribution of fatigue safety factor was calculated by using it Haigh diagram in which the maximum and the minimum stresses were selected from the five loading cases.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.214-218
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• 2008

Because on the high-tension underground distribution line of an electric railway high voltage XLPE Cable two or three circuits between railway stations with a standard as receiving transformer facilities are established at a $30km{\sim}50km$ interval, reactive power in which the phase of a current is larger than that of a voltage is supplied when trains are not working, so when there are no loading or low loading as night. Due to the long-distance trend of the underground distribution system on an alternating current railway distribution line, the terminal voltage of a transformer is over the standard voltage, and after all, commercial cycle overvoltage is continued. To solve this problem, the shunt reactor is installed in middle of power distribution lines to maintain receiver voltage meted under the allowance regulation through control of the reactive power. Also, in case that the thickness of single cable is over $60mm^2$ and length of line is about over 30km, a circuit breaker is broken by shorting shunt ability of charging current in excess of shunt current(31.5A.rms). Therefore, this thesis presents installing the location of shunt reactor for quantitative analysis by using optimum algorism for compensation and control of the charging current.

• Journal of Electrical Engineering and Technology
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• v.4 no.4
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• pp.438-442
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• 2009

Voltage instability is a phenomenon that could occur in power systems due to stressed conditions. The result would be an occurrence of voltage collapse leading to total blackout of the system. Therefore, voltage collapse prediction is an important part of power system planning and operation, and can help ensure that voltage collapse due to voltage instability is avoided. Line outages in power systems may also cause voltage collapse, thereby implying the contingency in the system. Contingency problems caused by line outages have been identified as one of the main causes of voltage instability in power systems. This paper presents a new technique for contingency ranking based on voltage stability conditions in power systems. A new line stability index was formulated and used to identify the critical line outages and sensitive lines in the system. Line outage contingency ranking was performed on several loading conditions in order to identify the effect of an increase in loading to critical line outages. Correlation studies on the results obtained from contingency ranking and voltage stability analysis were also conducted, and it was found that line outages in weak lines would cause voltage instability conditions in a system. Subsequently, using the results from the contingency ranking, weak areas in the system can be identified. The proposed contingency ranking technique was tested on the IEEE reliability test system.

• Journal of Korean Society of Water and Wastewater
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• v.19 no.6
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• pp.749-757
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• 2005

The present study analyzed actual cases of designed flow estimation method and designed flow rate of sewage pipe lines. In order to examine the effects of peak-hour demand factor estimation with given daily highest peak loading, we analyzed its effects on designed flow rate with changing the peak-hour demand factor from 2.0 to 10.0. The results of this study are as follows. When reviewing the recent designs, we found that 59.4% of pipe line with 250mm and 300mm diameter, which fall under minimum allowable pipeline did not meet the minimum velocity which is specified as 0.6m/sec in design standards. The pipe line that have minimal access population or have very low slope did not satisfy the minimum velocity. In estimating the designed sewage flow, the applied daily highest peak loading and hourly highest peaking loading were the load factor for the entire population of the planned area, and for the peak loading of the initial pipes connected to a very small population, we applied the same factor as that applied to the entire area and, as a result, the hourly highest flow was underestimated. Because, in case of the initial pipes, the method of applying the same peak loading to all subject areas is highly possible to produce underestimated design flow, when estimating the designed flow of the initial pipes connected to a small population need to adopt a rational flow factor according to the size of population. For this, it is considered to investigate and analyze raw data on daily and hourly variation of sewage flow.

• Proceedings of the KIEE Conference
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• 1996.07c
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• pp.1923-1924
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• 1996

Some part of the route in KEPCO 765kV transmission line being constructed passes through a high mountain area which is 800m above the sea level (Taebaek, Sabuk area in Gangwon province). This area is the top part of Taebaek mountains corresponding to the backbone of korean peninsula and has lots of snow during the winter season because the winter seasonal wind gone up along the mountainside of Taebaek Mts. meets open air of the East sea. KEPCO has experienced 63 faults of T/L between 1968 and 1993 in this area, which is a very serious problem. Especially 154kV Hwang-Ji T/L fault in 1990, 2 was a unprecedented case which needs to be analyzed carefully to take proper measures. After reviewing ice and snow loading conditions and analyzing the fault of Hwang-Ji T/L, we're going to determine the revisement of ice and snow loading condition in this area to increase reliability of 765kV transmission line.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.1426-1428
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• 2000

A new block system - MAS (Moving Autoblock System) whose efficiency is higher than FAS(Fixed Autoblock System) in the loading capacity is required to accomodate the increasing transport volume. That MAS has higher efficiency has already been verified through various studies, especially in a line with different types of travelling trains. The efficiency of MAS for Korean high speed line with two different train model is analyzed by computer simulation. The results show that MAS is more efficient than FAS in the loading capacity.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.11
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• pp.943-950
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• 2013

This paper discusses a harmonic response estimation method on the L$\acute{e}$vy plate with two opposite edges simply supported and the other two edges having free boundary conditions. Since the equation of motion of the plate is not self-adjoint, the modes are not orthogonal to each other on the domain. Noting that the L$\acute{e}$vy plate can be expressed using one term sinusoidal function that is orthogonal to other sinusoidal functions, this paper suggested the calculation method that is equivalent to finding a least square error minimization solution of the finite number of algebraic equations. Example problems subjected to a distributed area loading and a distributed line loading are defined and their solutions are provided. The solutions are compared to those of the commercial code, ANSYS. According to the verification results, it is expected that the suggested method will be useful to predict the forced response on the L$\acute{e}$vy plate with the distributed area or line loading conditions.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.6
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• pp.1111-1116
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• 2007

Antennas of the near field detection radar require little distortion in time domain caused by multi reflections between feed and open ends of the antenna, so that help to discriminate the target signal from the clutters. The resistive loading techniques have been used to reduce the late time distortions in order to prevent masking of target. In this paper, we design a microstrip antenna with two arms having sloted lines, which have inductance loading effect. Implemented antenna shows better performance on reducing late-time ringing, and the peak value of the received signal becomes 45% greater than the one by the antenna with two non-sloted lines.