• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.15 no.2
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• pp.21-30
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• 2001

In this paper, in the power system having UPFC(Unified Power Flow Controller) Power flow of certain line is controlled to desired value also power flow analysis algorithm is reposed considering power flow constraints which is capable of analysis power flow of all system. This algorithm is applied to controlling line-overloading problems and the method of is prosed. By applying this algorithm to controlling line-over loading the method of controlling UPFC is proposed and the effectiveness of controlling UPFC is proposed and the effectiveness of controlling UPFC is verified through the research of practical system. Also, the equation to set up an initial value of stories and shunt voltage source of UPFC is proposed for the effective power analysis.

• Proceedings of the KIEE Conference
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• 1999.11b
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• pp.282-284
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• 1999

This paper presents an accurate algorithm for fault location of a single phase to earth fault on a two-parallel transmission line using only one-terminal data. It is impossible to calculate the accurate fault distance, because of the unknown fault resistance and fault current at the fault point. The faulted line circuit and the zero-sequence circuit of two-parallel line are used as a fault location model, which the source impedance of the remote end is not involved. The algorithm can eliminate the effect of load flow and the fault resistance in calculating the fault location.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.9 no.1
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• pp.31-40
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• 2006

This paper describes the results of a series of field experiments which are carried out to assess the reduction effect of railroad vibration by utilizing waste tires. The ground vibration due to train service is measured in Honam Railroad line and Kyongbu Railroad line to assess the ground vibration with the domestic railroad line and train type before field model test. From the results of these tests, frequency on train service is presented from 5Hz to 100Hz and a range of excellence frequency is presented to be about from 20Hz to 40Hz in the domestic railroad line. Also, plate bearing tests are conducted to evaluate the variation of bearing capacity with different thickness of the waste tire layer and the fill layer. Finally, field model test is performed by using tire chips ($5cm{\times}5cm$ in size) as a reduction material of railroad vibration. The reduction effect of railroad vibration by utilizing waste tires increases with increasing the thickness of the waste tire layer and the frequency of the vibration source. The results of this experimental study was shown that the waste tire can be used for reduction of the railroad vibration.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.28 no.5B
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• pp.475-483
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• 2008

2D finite element model for analysis of transport of accidentally released pollutants in the flow was developed by SUPG method, and the mass balance of this model was checked though two example problems: line source and point source problem in the straight channel and unidirectional 2D flow field, respectively. All the test cases were simulated with both SUPG and conventional Galerkin method to compare the accuraccy of the numerical mass balance. Test results show that the model with SUPG can adequately conserve the released mass though simulation than the model using Galerkin method, so the developed model verified to be appropriate to solve this accidental mass release problem.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.40 no.1
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• pp.18-23
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• 1991

Recently SLAMECKA suggested the mathematical dynamic arc model of the SF6 gas circuit breaker [1]. The author applied the above dynamic arc model to the E.H.V. transmission line and investigated the interrupting capability of the SF6 gas circuit breaker. In particular the Runge-Kutta-England numerical method suitable for the use in systems that involve nonlinear dynamic arc and traveling wave was used by converting the current source into the voltage source in the DOMMEL's method [2]. The successful computer resultls were obtained and it was found that the arc time constant and the second derivative of the arc conductance are closely related to the interrupting capability of the SF6 gas circuit breaker.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.05a
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• pp.443-448
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• 2005

This paper proposed a regeneration inverter system, which can regenerate the excessive power form dc bus line to ac source for traction system. The proposed regeneration inverter system for dc traction can reduce harmonics which are include to ac current source. The regenerative inverter is operated as two modes. As a regeneration inverter mode, it can recycle regenerative energy caused by decelerating tractions and as an active power filter mode, it can compensate for harmonic distortion produced by the rectifier substation. In the paper, a regeneration inverter used PWM DC/AC converter algorithm. And an active power filter used p-q theory. The simulation was composed as a prototype model[3kW]. Simulation results show that two algorithm can be used to real model[100kW]. Finally, the inverter was successfully operated as regeneration mode.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.431-433
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• 2018

This paper proposes the system that offer super-wideband speech which is made by artificial bandwidth extension technique using wideband speech signal in time-domain. wideband excitation signal and line spectrum pair(LSP) are extracted based on source-filter model in time-domain. Two parameters are extended by each bandwidth extension algorithms, and then, super-wideband speech parameters are estimated. and synthesized. Subjective test shows super-wideband speech is better speech quality than wideband speech signal.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.3142-3147
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• 2008

A simple transient simulation of ground source heat pump system was carried out to investigate the effects of ground thermal conductivity on its performance. The TRNSYS code with a simple water to water heat pump model was used to compare the COP variation of the system. A new ground heat exchanger called by semi-closed loop was proposed and constructed in the real site. The effective thermal conductivity was measured using the test equipment developed by according to the line source model. The simulation results showed that highly efficient thermal conductivity of the grout material could increase the performance of the heat pump system very well. And the new ground heat exchanger showed the increased effective thermal conductivity as the penetration water flow rate(PWFR) was increased. Therefore, the performance improvement of the heat pump system using the proposed ground heat exchanger can be expected.

• Journal of the Korean Solar Energy Society
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• v.30 no.4
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• pp.15-21
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• 2010

Radiation data are the best source of information for estimating average incident radiation. Lacking this or data from nearby locations of similar climate, it is possible to use empirical relation ships to estimate radiation from days of cloudiness. It is necessary to estimate the regression coefficients in order to predict the daily global radiation on a horizontal surface. There fore many different equations have proposed to evaluate them for certain areas. In this work a new correlation has been made to predict the solar radiation for 16 different areas over Korea by estimating the regression coefficients taking into account cloud cover. Particularly, the straight line regression model proposed shows reliable results for estimating the global radiation on a horizontal surface with monthly average deviation of -0.26 to +0.53% and each station annual average deviation of -1.61 to +1.7% from measured values.

• The Journal of the Korea Contents Association
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• v.5 no.1
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• pp.9-17
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• 2005

In this paper we developed e-Leaning system based on open source software. We selected the Moodle that after compared the open source learning management systems. Moodle is LAMP(Linux, Apache, MySQL, PHP) based course management system (CMS), a software package designed to help educators create quality online courses. One of the main advantages of Moodle over other systems is a strong grounding in social constructionist pedagogy. Also we integrated Moodle and legacy systems such as streaming service, webhard service, and short message service. The system operated during one semester at college using blended learning model. We had obtained showed that the students had almost all scored quite highly as preferred learning environment through COLLES(Constructivist On-Line Learning Environment Survey) and ATTLS(Attitudes to Thinking and Learning Survey). Therefore this research showed that open source based e-Loaming system is stable and possible.