• Smart Structures and Systems
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• 제24권5호
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• pp.617-630
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• 2019

Currently most of the vision-based structural identification research focus either on structural input (vehicle location) estimation or on structural output (structural displacement and strain responses) estimation. The structural condition assessment at global level just with the vision-based structural output cannot give a normalized response irrespective of the type and/or load configurations of the vehicles. Combining the vision-based structural input and the structural output from non-contact sensors overcomes the disadvantage given above, while reducing cost, time, labor force including cable wiring work. In conventional traffic monitoring, sometimes traffic closure is essential for bridge structures, which may cause other severe problems such as traffic jams and accidents. In this study, a completely non-contact structural identification system is proposed, and the system mainly targets the identification of bridge unit influence line (UIL) under operational traffic. Both the structural input (vehicle location information) and output (displacement responses) are obtained by only using cameras and computer vision techniques. Multiple cameras are synchronized by audio signal pattern recognition. The proposed system is verified with a laboratory experiment on a scaled bridge model under a small moving truck load and a field application on a footbridge on campus under a moving golf cart load. The UILs are successfully identified in both bridge cases. The pedestrian loads are also estimated with the extracted UIL and the predicted weights of pedestrians are observed to be in acceptable ranges.

• Journal of Electrical Engineering and Technology
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• 제8권3호
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• pp.446-452
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• 2013

Under frequency load shedding (UFLS) is an effective way to prevent system blackout after a serious disturbance occurs in a power system. A novel centralized adaptive under frequency load shedding (AUFLS) scheme using the synchronous phase measurement unit (PMU) is proposed in this paper. Two main stages are consisted of in the developed technique. In the first stage, the active power deficit is estimated by using the simplest expression of the generator swing equation and static load model since the frequency, voltages and their rate of change can be obtained by means of measurements in real-time from various devices such as phase measurement units. In the second stage, the UFLS schemes are adapted to the estimated magnitude based on the presented model. The effectiveness of the proposed AUFLS scheme is investigated simulating different disturbance in IEEE 10-generator 39-bus New England test system.

• 한국물환경학회지
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• 제25권6호
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• pp.972-978
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• 2009

This study modifies the present total maximum daily load (TMDL) system of Ministry of Environment and applies to the Anyangcheon watershed. Hydrologic Simulation Program-FORTRAN (HSPF) model is used to simulate both runoff and non-point source pollution, simultaneously, instead of QUAL2E. The drought flow (355th daily flow) is proposed for the target water quantity since it is easier to satisfy low flow (275th daily flow) for the target water quality than drought flow. The increase of discharge is more than the increase of pollutant load except for the period under low flow. The measured unit loads for non-point source are used to consider the regional runoff characteristics. The measured water quantity and quality data are used since the ministry of environment supports only water quality. This analysis results show some reasons for the improvement of the present TMDL system of Korea.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1707_1708
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• 2009

Unit master control(UMC)는 발전소의 요구 부하신호를 설정하는 최상위의 제어레벨이며 UMC의 설정값은 자동급전 지령신호(Automatic Dispatch System : ADS) 또는 운전원이 설정하는 값에 따라 보일러 및 터빈 Master에 Unit 요구 신호를 출력하여 하위제어 레벨인 공기, 연료, 급수 등을 조절할 수 있는 기기에 Unit 부하 요구 신호(Unit Load Demand : ULD)에 따라 제어 되도록 하는 방법으로서, Unit 목표부하 설정, Unit 목표부하 상/하한 제한, 목표부하 변화율 제한, 주파수 보정, Runback/Rundown/ Runup, 보일러 및 터빈 Demand 신호생성의 기능을 가지고 있다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2000년도 하계학술대회 논문집 B
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• pp.778-780
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• 2000

Due to the long time operation of the thermal power plant boiler. the load redistribution of the sling rods is occurred. To enlarge the sincerity of the boiler. measuring and adjusting the actual load of the sung rods is required. The original targets were reached from the 1-year-study. Survey related to the load distribution system for the boiler, systematic design of the hydraulic unit and hydro cylinder, detailed design of the hydraulic unit and hydro cylinder.

• 한국안전학회지
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• 제14권2호
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• pp.155-162
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• 1999

reliability from components reliability. In this case, it assumes that components failure is mutually independent, but it may not true in real systems. In this study, the mean cost per unit time is computed as the ratio of mean life to the mean cost. The mean life is obtained by the reliability function under power rule model. The mean cost is obtained by the mathematical model based on the inspection interval. A heuristic method is proposed to determine the optimal number of redundant units and the optimal inspection interval to minimize the mean cost per unit time. The assumptions of this study are as following : First, in the load-sharing k-out-of-n:G system, total loads are applied to the system and shared by the operating components. Secondly, the number of failed components affects the failure rate of surviving components as a function of the total load applied. Finally, the relation between the load and the failure rate of surviving components is set by the power rule model. For the practical application of the above methods, numerical examples are presented.

• 전기의세계
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• 제18권3호
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• pp.7-14
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• 1969

According to the construction of Seoul Thermal #5 (250MW) unit, there will be prospected several new problems on the power system operation. This paper describes the characteristic of system frequency decay during severe emergencies which result in sudden outage of such large generator unit. It also studies the factors involved in applying under frequency relays to maintan an allowable frequency level and to prevent total area collapse by automatic load shedding program.

• 한국철도학회논문집
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• 제3권1호
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• pp.1-11
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• 2000

In this paper, the IGBT VVVF inverter for 1C4M propulsion system of railway traction is studied. The inverter is consisted of IGBT stacks, a DB unit, and a control unit. The test results of the combined system is given, which shows an excellent performance of the overall system.

• International Journal of Air-Conditioning and Refrigeration
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• 제11권4호
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• pp.170-177
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• 2003

The electric power load during the summer peak time is strongly affected by cooling load, which decreases the preparation ratio of electricity and brings about the failure in the supply of electricity in the electric power system. The ice storage system and heat pump system etc. are used to settle this problem. In this study, the method of estimating temperature and humidity to forecast the cooling load of ice storage system is suggested. The method of forecasting the cooling load using neural network is also suggested. The daily cooling load is mainly dependent on actual temperature and humidity of the day. The simulation is started with forecasting the temperature and humidity of the following day from the past data. The cooling load is then simulated by using the forecasted temperature and humidity data obtained from the simulation. It was observed that the forecasted data were closely approached to the actual data.

• 한국철도학회논문집
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• 제11권6호
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• pp.562-568
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• 2008

현대의 물류는 파렛트를 활용한 일관운송체계로 변화하고 있다. 더불어 포장용기의 적재율과 타 수송수단과의 정합성을 높이려는 노력도 병행되고 있다. 이와 같은 일련의 추세는 물류의 효율화를 통한 물류비 절감이라는 명제에 기반을 둔다. 파렛트를 이용한 일관수송에서 기본이 되는 것은 포장의 단위이다. 개별 포장의 크기와 형태가 포장용기의 적재율을 최대화시키도록 하는 것이 관건이기 때문이다. 또한 포장용기는 이차적으로 수송수단의 적재함이나 보관시설 등 연관된 물류활용에 영향을 미치기 때문에 포장의 단위가 미치는 파급의 범위는 넓다. 본 연구의 목적은 포장모듈 표준화 사업의 효과를 평가하는 척도(MOE)를 선정하고 이를 반영한 평가모형을 개발하는데 있다. 선행연구의 사례와 타 학문분야의 계량화 방법 등을 토대로 포장모듈의 표준화가 물류산업에 미치는 영향을 파악하고 이를 계량화하는 방안을 제시한다. 연구의 방법론적 측면에서 볼 때 물류활동 부문별로 나타나는 포장모듈 표준화의 효과를 어떠한 방법으로 계량화하고 가중치를 두어 하나의 대표값으로 추출하느냐가 관건이 된다.