• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2005.11a
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• pp.399-403
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• 2005

In this paper, we analyze on the effect of RC filter to mitigate transient overvoltage on the high voltage induction motor fed by H-bridge cascaded 7-level inverter. The switching surge voltage becomes the major cause to occur the insulation failure by serious voltage stress in the stator winding of high voltage induction motor. The effect of switching surge appears more serious in high voltage induction motor than low voltage induction motor. Consequently, we demonstrated that the RC filter connected to the motor terminals greatly reduces the transient voltage stress md ringing. The results of simulation show the suppression of transient overvoltage at the motor end of a long cable. using EMTP

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 1998.05a
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• pp.199-203
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• 1998

종합유선방송의 고기능화란 기존의 다채널만을 수용한 단순 종합유선방송뿐만 아니라 채널의 광대역화를 통한 쌍방향 통신의 개발로 이를 이용한 전화 서비스, 대화형 영상 서비스, 고속 인터넷 서비스와 같은 고도의 정보 통신 서비스까지 제공할 수 있는 새로운 자원의 정보통신 미디어로 발전된 것을 말한다. 그러나 우리 나라의 종합유선방송 사업은 많은 발전 가능성에도 불구하고 무리한 일정과 근시안적인 제도로 인해 시행 초기부터 프로그램의 제작 및 배분, 종합유선방송 사업자의 선정, 망의 설치 및 관리 둥에서 많은 문제점을 안고 있어 고기능 종합유선방송으로의 발전을 위한 제도적 대응방안이 요구되고 있다. 따라서 본 논문에서는 우리 나라의 종합유선방송의 제도의 문제점을 종합적으로 분석하고, 우리 나라에서 종합유선방송의 고기능화를 위한 제도적 대응 방안을 기술적인 측면과 정책적인 측면으로 나누어 제안하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2018.06a
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• pp.35-38
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• 2018

최근 미디어 소비 환경은 지상파 방송과 같은 Mass Media 중심에서 모바일, Multi Device 기반의 개인화 서비스 위주로 변화하고 있다. 이에 따라 국내외 다양한 유료방송사, 통신사, 지상파 방송 사업자들은 변화하는 미디어 소비환경에 유연하게 대응할 수 있는 차세대 방송 플랫폼 도입을 위한 연구를 진행하고 있다. 이에 본 논문은 케이블TV 방송사업자가 변화하는 미디어 소비 환경에 유연하게 대처할 수 있는 IP기반 방송 플랫폼에 대해 연구하였다. 이를 위하여 실감 미디어 제공을 위한 양방향 미디어 전송 환경의 연구와 MPEG의 차세대 미디어 전송을 위한 표준화 현황을 알아보고, IP기반의 방송 플랫폼의 필요성 그리고 플랫폼의 구조에 대하여 설계 하였다.

• Journal of Korean Society of Forest Science
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• v.111 no.4
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• pp.583-593
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• 2022

The harvesting system in South Korea faces the problems of aging workers and high wages, so it is necessary to improve the operation system and train workers to use high-performance forestry machines. This study compared the effectiveness and costs of yarding and processing operations between a multi-operation system using a tower yarder (HAM300) and a processor (KESLA 20SH) with those of a single-system using a forestry combi-machine. A whole-tree (cable) yarding operation was conducted in the clear-cutting area located at Compartment 15, Gwangneung Experimental Forest, National Institute of Forest Science, and the productivity and cost of multi- and single-system were analyzed. The productivity of the single-system was 1.5 m³/PMH and 1.6 m³/PMH higher than that of the multi- system because the single-system produced 1 log/cycle more than the multi-system in the yarding operation. The cost was approximately 12.1% lower for the single-system (￦36,113/m³) than for the multi-system (￦41,065/m³). The costs of the single-system and multi-system were decreased by maximums of 22.6% and 15.9%, respectively, by decreasing the idle time.

• Proceedings of the KIEE Conference
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• 2006.05a
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• pp.74-77
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• 2006

This research is focused on the development of GIS Diagnostic SYSTEM to prevent accidents beforehand by inspecting the internal defects of GIS (Gas Insulated Switchgear) which is a main power-facility for substations. GIS Diagnostic SYSTEM is categorized as 'Real time on-line test type' and 'Portable test type' depending on the types of testing, it uses PD(partial discharge) which mostly incurs in GIS internal defects, to inspect. As of now, mostly foreign equipments are imported for use due to the lack of the technology localization, and these are installed and operated on only some parts of highly-graded GIS power-facilities such as in 76skv or 345kv for its being expensive. Furthermore, other than foreign equipments being costly, it also has a weak point of very long unavailability in case of Diagnostic system break-down while using, because it takes a comparatively long period of corrective maintenance precesses. We have localized to develop personal real-time multi -functional GIS Diagnostic system which can test on all GIS power-facility comprehensively and economically therefore overcome all these problems mentioned above, a market expansion is expected from the decrease of price and replacing the import equipments in the future. As the equipment was developed to be Personal for the simple ways of installing and utilizing, it can be operated without any complex cable installation like other existing GIS Diagnostic system requires, therefore also decrease the cost of cable installation.

• Journal of KIISE:Computing Practices and Letters
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• v.7 no.6
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• pp.593-601
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• 2001

This paper presents an efficient system for power system education using 3-D computer graphics animation in the PC environment. Several power system phenomena are simulated using Real-Time Digital Simulator. Results are transmitted through on-line communication line to PC for graphic animation, and simulated in the 3-D graphics animation. It can immediately reflect user control input and re-simulated this result. The proposed method was tested on both the sub-synchronous resonance phenomena and multi-bus system. It is expected that the proposed method would be helpful for the operator training as well as power system education.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.3
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• pp.45-52
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• 2006

In this paper, we analyze on the effect of LCR filter to mitigate transient overvoltage on the high voltage induction motor fed by H-bridge cascaded 7-level inverter. The switching surge voltage that it was occurred in inverter appears transient overvoltage at the motor input terminal. the transient overvoltage becomes the major cause to occur the insulation failure by serious voltage stress in the stator winding of high voltage induction motor. The effect of transient overvoltage appears more serious in high voltage induction motor than low voltage induction motor. We selected LCR filter for reduction of the transient overvoltage. Consequently, we demonstrated that the LCR filter connected to the invertor output terminals greatly reduces the transient voltage stress and ringing. The results of simulation show the suppression of transient overvoltage at the motor end of a long cable. using EMTP

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.9
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• pp.4447-4454
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• 2013

In October 2011, a commercialized 100kW class floating photovoltaic system positive plant was installed at Hapcheon dam a multi-purpose reservoir the first time ever in the nation. Floating photovoltaic system differs in water float, mooring device and underwater cable process from land photovoltaic system. As for land and building photovoltaic power generation equipments, many installation cases and skilled experiences are available, and thus installation is not difficult. However, commercial power generation floating photovoltaic system, which is attempted for the first time in the nation, requires to be designed and installed through a series of processes like technical review and verification of data by process in comparison with similar cases. The structure of floating photovoltaic system, an equipment for float photovoltaic module and other electrical equipment, is required to withstand weather environments like wind or typhoon etc and yet not affect water quality negatively, and for implementation of this system, construction efficiency and economy etc should be considered comprehensively. In this paper, the techniques of installing floating photovoltaic structure, mooring device, underwater cable, electrical equipment and remote monitoring control system are explained. The 100kW floating PV system is operating with 15% average capacity factor.

• Structural Engineering and Mechanics
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• v.80 no.6
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• pp.749-765
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• 2021

Suspension bridges bear large eccentric live loads in rush hours when most vehicles travel in one direction on the left or right side of the bridge. With the increasing number and weight of vehicles and the girder widening, the eccentric live load effect on the bridge behavior, including bending and distortion of the main girder, gets more pronounced, even jeopardizing bridge safety. This study proposes an analytical algorithm based on multi-catenary theory for predicting the suspension bridge responses to eccentric live load via the nonlinear generalized reduced gradient method. A set of governing equations is derived to solve the following unknown values: the girder rigid-body displacement in the longitudinal direction; the horizontal projection lengths of main cable's segments; the parameters of catenary equations and horizontal forces of the side span cable segments and the leftmost segments of middle span cables; the suspender tensions and the bearing reactions. Then girder's responses, including rigid-body displacement in the longitudinal direction, deflections, and torsion angles; suspenders' responses, including the suspender tensions and the hanging point displacements; main cables' responses, including the horizontal forces of each segment; and the longitudinal displacement of the pylons' tower top under eccentric load can be calculated. The response of an exemplar suspension bridge with three spans of 168, 548, and 168 m is calculated by the proposed analytical method and the finite element method in two eccentric live load cases, and their results prove the former's feasibility. The nonuniform distribution of the live load in the lateral direction is shown to impose a greater threat to suspension bridge safety than that in the longitudinal direction, while some other specific features revealed by the proposed method are discussed in detail.

• Journal of Korea Multimedia Society
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• v.9 no.10
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• pp.1322-1331
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• 2006

Concurrency control is one of the important factors to maintain consistent conditions of a game because most participants of the game should be shared information to play the game through a distributed network system. replay delay times should establish in every event and the received event should be saved and performed simultaneously for Concurrency Control. However, it is not easy to practice the event with same speed in environment having various moving speed. Therefore, expansion have to be provided. In other words, one of the most important factors of a game's efficiency is the process of bandwidth and delay. the process of concurrency control method based on scalable prediction for Multi-platform games would minimize the loss rate of a event and then would improve the interaction capacity of a game. It also might get reliability between clients. This paper analyzes some problems in terms of a layout of a game that integrates a cable and a wireless system. In addition, this paper provides methods to expand bandwidth and delay that might be an obstacle of a On-line game and to ensure reliability between a server and a client.