Yonam Institute of Digital Technology

Chinju, South Korea

Yonam Institute of Digital Technology

Chinju, South Korea
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Seo H.-C.,Yonam Institute of Digital Technology | Joon-Han,Sungkyunkwan University | Choi S.-K.,Korea Electric Power Research Institute | Lee B.-S.,Korea Electric Power Research Institute | And 2 more authors.
Journal of Electrical Engineering and Technology | Year: 2016

The Korean distribution line currently consists of overhead ground wires (OHGW), overhead distribution lines, neutral wires (NW), and messenger wires (MW). The MW is installed under the NW. The lightning protection system in Korea is focused on OHGW and lightning arrester and the MW are not considered. Therefore, this paper proposes the applicability of MW for purpose of lightning protection. For this, we analyzed the effects of lightning overvoltage according to the existence of OHGW and MW and the grounding conditions of the MW in the Korean distribution system. The grounding conditions of the MW that we took into consideration were the common or separate grounding of the MW and NW. The analysis based on the equivalent circuit of the distribution pole at each condition was performed. The distribution lines and lightning were modeled using the Electromagnetic Transients Program (EMTP). For each of the installation conditions of the OHGW and MW, the various lightning conditions were simulated and analyzed for both direct and indirect lightning. The simulation results showed that, if the OHGW was not installed in the Korean distribution system, the lightning overvoltage could be reduced by the common grounding of the MW and NW. © The Korean Institute of Electrical Engineers.


Seo H.-C.,Yonam Institute of Digital Technology | Joon-Han,Sungkyunkwan University | Choi S.-K.,Korea Electric Power Research Institute | Lee B.-S.,Korea Electric Power Research Institute | Kim C.-H.,Sungkyunkwan University
Journal of Electrical Engineering and Technology | Year: 2016

Because of the random characteristics of lightning, the Monte Carlo method is applied to estimate the flashover rate due to lightning, however, the simulations using previous methods are difficult to both beginner and expert in power corporations. Therefore, this paper proposes the new and easy method to simulate the flashover rate by connection of electromagnetic transients program (EMTP) and MATLAB. The magnitude of a lightning strike is based on a curve measured in the field, while the classification of direct and indirect lightning depends on the striking distance. In a Korean distribution system, the flashover rate induced by lightning is simulated using proposed method. Simulations of the footing resistance according to the existence of an overhead ground wire (OHGW) are performed and the simulation results are discussed. The simulation results are compared with findings obtained with the IEEE Flash 2. 0 program. © The Korean Institute of Electrical Engineers.


Lee J.-W.,Sungkyunkwan University | Kim W.-K.,Sungkyunkwan University | Oh Y.-S.,Sungkyunkwan University | Seo H.-C.,Yonam Institute of Digital Technology | And 4 more authors.
Journal of Electrical Engineering and Technology | Year: 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. © 2015, The Korean Institute of Electrical Engineers.


Heo J.-Y.,Sungkyunkwan University | Seo H.-C.,Yonam Institute of Digital Technology | Lee S.-J.,Korea University | Kim Y.S.,Korea University of Technology and Education | Kim C.-H.,Sungkyunkwan University
Journal of Electrical Engineering and Technology | Year: 2014

The current flowing through the overhead transmission lines causes induced voltage on the communication lines, which can be prevented by calculating the induced voltage at the planning stage for overhead transmission line installment through an agreement between the communication and electric power companies. The procedures to calculate the induced voltages, however, are complicated due to the variety of parameters and tower types of the overhead transmission lines. The difficulty necessitates the development of a simulator to measure the induced voltage on the communication lines. This paper presents two simulators developed for this purpose; one using the Data Base (DB) index method and the other using the Graphic User Interface (GUI) method. The simulators described in this paper have been implemented by the EMTP (Electromagnetic Transient Program).


Park B.K.,Yonam Institute of Digital Technology | Yi N.,Pohang University of Science and Technology | Park J.,Pohang University of Science and Technology | Kim Y.,Catholic University of Korea | Kim D.,Pohang University of Science and Technology
AIP Advances | Year: 2014

This paper presents a novel biothermal sensor to probe cell viability and concentration of a cell suspension. The sensing technique exploits the thermophysical properties of the suspension, so no labeling of suspended cells is required. When the sensor is periodically heated, the amplitude and phase of the thermal signal are dependent on the thermal properties of the cell suspension, particularly the thermal conductivity k. We measured k of HeLa, hepatocyte, and NIH-3T3 J2 cell suspensions with various concentrations and viabilities. The results demonstrate that the k of a cell suspension has a strong correlation with its concentration and viability. Accordingly, k can be employed as an index of cell concentration and viability. Furthermore, without data processing to obtain k, the electric signal that reflects the thermal response of the sensor can be used as a tool to probe viability of a cell suspension in real time. The proposed thermal sensing technique offers label-free, non-invasive, long-term, and real-time means to probe the viability and concentration of cells in a suspension. © 2014 Author(s).


Oh Y.-S.,Sungkyunkwan University | Seo H.-C.,Yonam Institute of Digital Technology | Yang J.-J.,Korea Power Exchange | Kim C.-H.,Sungkyunkwan University
Journal of Electrical Engineering and Technology | Year: 2014

It is well known that line switching operations like reclosing are able to cause transient power oscillations which can stress or damage turbine generators. This paper presents a reclosing scheme to reduce the shaft torsional torques of turbine generators by inserting an additional reactor. A novel method to determine optimal reactor capacity to minimize the torsional torque generated in a turbine generator is also proposed. In this paper, the turbine generator shaft is represented by a multi-mass model to measure torsional torques generated in the shaft between the turbine and the generator. Transmission systems based on actual data from Korea are modeled to verify the proposed scheme using ElectroMagnetic Transient Program (EMTP) software. The simulation results clearly show the effectiveness of the proposed scheme and torsional torque can be minimized by applying the proposed scheme.


Kim C.-H.,Yeungnam University | Seo H.-C.,Yonam Institute of Digital Technology | Rhee S.-B.,Yeungnam University | Kim C.-H.,Sungkyunkwan University
IET Conference Publications | Year: 2014

This paper proposes an application of superconducting fault current limiter (SFCL) to reduce the AFC, especially decision method of optimal insertion resistance of SFCL. The proposed method employs an auxiliary SFCL and main SFCL connected in series. The optimal reducing level of AFC is that the peak value of AFC is limited to steady-state fault current. Based on this concept, the equation to determine the resistance of SFCL is developed. The distribution system and SFCL is modeled by an electromagnetic transient program (EMTP)/ATPDraw to verify the effectiveness of the proposed method. The simulations according to the existence of SFCL and X/R ratio of source impedance are performed and the results are analysed.


Heo J.-Y.,Sungkyunkwan University | Oh Y.-S.,Sungkyunkwan University | Seo H.-C.,Yonam Institute of Digital Technology | Kim C.-H.,Sungkyunkwan University
Journal of Electrical Engineering and Technology | Year: 2015

Autoreclosure provides a means of improving power transmitting ability and system stability. Conventional reclosure adopts the fixed dead time interval strategy, where the reclosure is activated after a time delay to restore the system to normal as quickly as possible without regard to the system conditions. However, these simple techniques cannot provide optimal operating performance. This paper presents an adaptive autoreclosure algorithm including variable dead time, optimal reclosure, phase-by-phase reclosure and emergency extended equal-area criterion (EEEAC) algorithm in order to improve system stability. The reclosure algorithm performs the operations that are attuned to the power system conditions. The proposed adaptive reclosure algorithm is verified and tested using ATP/EMTP MODELS, and the simulation results show that the system oscillations are reduced and the transient stability is enhanced by employing the proposed adaptive reclosure algorithm. © 2015, The Korean Institute of Electrical Engineers.


Park J.-H.,Hyosung Corporation | Seo H.-C.,Yonam Institute of Digital Technology | Kim C.-H.,Sungkyunkwan University | Rhee S.-B.,Yeungnam University
Electric Power Components and Systems | Year: 2016

This article proposes an adaptive operating scheme for a recloser based on classified detection of transient faults and permanent faults in a distribution system. Wavelet transform is used to classify whether a fault is transient or permanent in nature. The Haar mother wavelet of the current flowing in a neutral line has more rich harmonics than other mother wavelets, such as Daubechies, Symlets, Coiflets, and Biorthogonal, so the total harmonic distortion of the Haar mother wavelet is applied for estimating the instant of fault clearance and giving a signal for operating action to the recloser (reclosing). The various simulations according to the fault clearance time and fault type are performed using the Electromagnetic Transient Program to verify the proposed algorithm. The simulation results show the effectiveness of the proposed algorithm. 2016 Copyright © Taylor & Francis Group, LLC


Lee H.W.,Pusan National University | Lee K.O.,Pusan National University | Chung D.H.,Yonam Institute of Digital Technology
Proceedings of the Institution of Mechanical Engineers, Part C: Journal of Mechanical Engineering Science | Year: 2010

This study gives an exact definition of the spherical involute curved face and the pitch azimuthal angle of a bevel-geared system. Using the coordinate-transformation method, it derives the kinematic relations between the operating pressure angles, pitch azimuthal angles, operating pitch cone angles, base cone angles, and pitch action angles. An exact spherical involute bevel gear illustrates that a spherical involute tooth profile can be modelled only if the operating pressure angle, operating pitch cone angle, number of teeth, and cone radius are given. The ratio of the angular speeds of the spherical involute bevel gear reveals that the comparison of a bevel gear with a cone friction wheel is similar to the situation in which a belt that is wound around a base cone becomes untied and is wound around the base cone of the other party. The findings confirm that even when the shaft angle changes, the ratio of angular speeds does not change. This study also exactly calculates the operating rate in an involute bevel gear in a theoretical manner. To review interchangeability, the study defines the angular pitch and the crown number of teeth and shows that the proposed spherical involute bevel gear possesses interchangeability. To verify the contact phenomenon of the spherical involute bevel gear, a computer-graphic verification is conducted on three models to see whether gear interference occurs when two gears are operating while going in gear with each other. © 2010 Authors.

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