• 스마트미디어저널
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• 제12권5호
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• pp.81-87
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• 2023

전력계통에서 안정적인 전력공급을 하는 고압 가공 배전선로의 사고 발생으로 생활의 불편과 더불어 기업의 생산 차질을 초래하게 된다. 22.9[kV] 고압 가공 배전선은 평소 비, 눈, 바람 등에 의한 피해나 감전방지 등의 신뢰성 및 안정성의 향상을 목적으로 하고 있다. 이에 가공 배전선로의 부식으로 인한 전선의 도전율을 저하시키거나 인장강도가 저하되어 단선 사고를 미연에 방지하기 위하여 평소에 점검과 보수를 통하여 미래의 예기치 못한 사고를 미리 방지하여야 한다. 배전선로의 부식으로 인한 열화진단을 하기 위하여 전선에 진단시스템(계측기)를 설치하여 전선의 상태를 모니터링한다. 측정된 데이터를 ZigBee 무선통신으로 지상의 관리자가 받아 진단시스템 프로그램을 통하여 진단시스템의 제어와 측정된 데이터 및 촬영된 사진을 통하여 가공 배전선로의 상태를 파악하여 육안 검사 방법과 더불어 전선의 수명을 예측하는 프로그램을 개발하였다.

• 농업생명과학연구
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• 제44권3호
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• pp.7-14
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• 2010

Alternative subirrigation way, capillary wick system (CWS) was tested to reduce labor cost, waste water, contamination of ground water, and use of fungicide compared to overhead irrigation system (OIS). CWS helped reduce remarkably the working hours for watering from 4 hours in OSI to just 5 minutes. Labor cost was saved 98% in CWS compared to OIS. By the physical characteristics of various growing media, 1 coconut coir+2 perlite (v/v) mixture was selected because it had an ideal distribution of three phase, e.g. 1 solid: 1 liquid: 2 gas phase. Medium mixture containing scoria had so high bulk and particle density to hurt root. In bark-containing medium, the liquid phase and the percent saturation of liquid phase with time elapsed was lower than that of other mixture. It meant that the mixture contained very low level of water. Application of CWS for cyclamen pot production played an important role in reducing the incident of fusarium wilt symptom from 18% in conventional over watering system to 4%. Cyclamen pot irrigated by capillary wick had shorter petiole and more leaves than those by overhead watering. As a result, this system was highly beneficial to get uniform pot products with high quality. It improved water and nutrient solution efficiency relative to conventional overhead irrigation system (OIS).

• 한국멀티미디어학회논문지
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• 제11권6호
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• pp.860-868
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• 2008

Human detection techniques in outdoor scenes have been studied for a long time to watch suspicious movements or to keep someone from danger. However there are few methods of human detection in overhead or near-field view scenes, while lots of human detection methods in far-field view scenes have been developed. In this paper, a set of five features useful for human detection in overhead view scenes and another set of four useful features in near-field view scenes are suggested. Eight feature-candidates are first extracted by analyzing geometrically varying characteristics of moving objects in samples of video sequences. Then highly contributed features for each view scene to classifying human from other moving objects are selected among them by using a neural network learning technique. Through experiments with hundreds of moving objects, we found that each set of features is very useful for human detection and classification accuracy for overhead view and near-field view scenes was over 90%. The suggested sets of features can be used effectively in a PTZ camera based surveillance system where both the overhead and near-field view scenes appear.

• 전기학회논문지
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• 제66권4호
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• pp.740-744
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• 2017

Overhead Line is divided by two systems which are OCS (Overhead Catenary Line) and R-Bar (Overhead Rigid Conductor system). R-Bar has an advantage of maintenance and economic aspect comparing with OCS. R-Bar in Korea has developed for the max. speed of 120km/h, but it is evaluated up to the max. speed of 250 km/h in Europe. There are lots of mountains and underground sections in korea, it is really necessary to develop the R-Bar for a high-speed line. In the study, design parameters for the max. speed of 250 km/h of R-Bar was proposed. A bracket space, stiffness, and especially an installation tolerance of contact wire height at a bracket were considered as a parameter, and a dynamic behavior between a contact wire and pantograph was predicted by evaluated FEM simulation tool. The installation tolerance and bracket space are more important for the high-speed system. The proposed parameters was decided very conservative. Because the aerodynamic characteristics of a pantograph in tunnel is more severe than an open route and the simulation tool is not considered the such kind of aerodynamic characteristics.

• 전기학회논문지
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• 제62권4호
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• pp.474-481
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• 2013

It is anticipated that AC distribution system can be replaced by DC distribution system in the near future because of the operation of various distributed source or microgrid system. However DC distribution system replacing 22.9kV AC distribution line is not sufficiently studied still. This paper describes lightning overvoltage analysis among many research fields should be studied to realize DC overhead distribution systems. DC distribution system is modeled using EMTP and overvoltage is analyzed according to interval of arrestor location, earth interval of overhead grounding wire and grounding resistance. It is evaluated that analysis results can be effectively used to design of future DC distribution system.

• 한국전기전자재료학회논문지
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• 제22권10호
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• pp.864-869
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• 2009

The measurement of contact wire uplift in electric railways is one of the most important test parameters to accepting the maximum permitted speed of new electric vehicles and pantographs. The contact wire uplift can be measured over short periods when the pantograph passes monitoring stations. In this paper, a high-speed image measurement system and its image processing method are being developed to evaluate dynamic uplift of overhead contact wires caused by pantograph contact forces of Korea Tilting Train eXpress (TTX) and Korea Train eXpress (KTX). The image measurement system was implemented utilizing a high-speed CMOS (Complementary Metal Oxide Semiconductor) camera and gigabit ethernet LAN. Unlike previous systems, the uplift measurement system using high speed camera is installed on the side of the rail, making maintenance convenient. On-field verification of the uplift measurement system for overhead contact wire using high speed camera was conducted by measuring uplift of the TTX followed by operation speeds at the Honam conventional line and high-speed railway line. The proposed high-speed image measurement system to evaluate dynamic uplift of overhead contact wires shows promising on-field applications for high speed trains such as KTX and TTX.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2010년도 하계학술대회 논문집
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• pp.115-115
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• 2010

This paper introduces a measurement system that measures behavior and electrical characteristics of overhead contact line irregular sections in real-time. For verification, we developed a prototype of the real-time overhead contact line irregular section behavior measurement system and a monitoring system for field tests. The current and temperature of contact wires and messenger wires were measured real-time by applying the system at KTX a commercial line. Therefore, acquiring data is possible with the developed system and this system that measures one of the fundamental and key factors, the catenary current, should be applicable to various areas such as detecting characteristics for designing overhead contact lines, enhancing speed, and enhancing energy.

• 한국정밀공학회지
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• 제22권4호
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• pp.128-135
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• 2005

Overhead crane systems consist of trolley, girder, rope, objects, trolley motor, girder motor, and hoist motor. The dynamic system of these systems becomes a nonlinear state equations. These equations are obtained by the nonlinear equations of motion which are derived from transfer functions of driving motors and equations of motion for objects. From these state equations, Lyapunov functions of overhead crane systems are derived from integral method. These functions secure stability of autonomous overhead crane systems. Also constraint equations of driving motors of trolley, girder, and hoist are derived from these functions. From the results of computer simulation, it is founded that overhead crane systems is secure.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.748-750
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• 2004

The pantograph should supply the electrification equipments of a train with the current from the overhead catenary system over a broad range of speeds. For a high-speed electrical train, the dynamic interaction between the pantograph and the overhead catenary system causes the variation of the contact force. As the operational speed increases, the variation of the contact force increases. The contact force variation can cause contact losses, arcing and sparking. If the spark happens between the pantograph and the overhead catenary system, the EMI(electro magnetic interface) and noises may occur. After all, the quality of current collection is deteriorated. This paper deals with the dynamic characteristics analysis between pantograph and catenary system using block pulse function.

• 전기학회논문지
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• 제62권6호
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• pp.886-890
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• 2013

Uplift of contact wire and dynamic characteristics between pantograph and contact wire are key interaction performance of OCS (Overhead Catenary System). These two evaluation items are the approval criteria for the performance between OCS and pantograph. A telemetry system or DAQ (Data Acquisition) System based on wireless communication make it monitor a dynamic behavior which is measured directly in a 25 kv like parts. While permissible working time is too short time to install is too long. In this paper, it is described that optimization the telemetry measurement system for OCS and increasing accuracy, easy adaptation, and faster handling can be also achieved through the study.