• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.11a
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• pp.862-865
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• 2004

The system air conditioner has an outdoor unit and a number of indoor units, which connected by several long pipes. In comparison with building HAVC system, the system air conditioner doesn't need lots of facilities, such as control of room, cooling tower, etc. At the beginning stage for the market of the system air conditioner, its main application was a school which size is small to use the building HAVC and large to use home air conditioning system, such as PAC (package air conditioner), RAC (room air conditioner). Therefore, because of the advantages of the system air conditioner mentioned above, the market is expanded rapidly. Since it is difficult to evaluate the noise caused by the system air conditioner because it has to be implemented before the finish of construction, the prediction or estimation of the noise by using CAE technology should be very important. In this research, using a commercial code, RAYNOISE, the noise is estimated to improve the design of building.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.25 no.4
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• pp.365-372
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• 2007

Enterprises requires the logistics information system to reduce logistics costs and ensure clearness of distribution. However, the system is adopted only by large corporations due to diversity of work and the initial cost for construction. In this study We have attempted to develop an information system capable of efficiently. Controlling and managing logistics by investigating division of duties and existing problem. Using small and medium-sized enterprises engaged in the distribution business as a model. For real-time monitoring of logistics information. We have constructed a system using new technologies such as GPS, mobile and wireless communications and made use of web GIS as infrastructure. Developed by the logistics information systems, We will control overall logistics work and reduce logistics costs and processing time as well.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2001.11a
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• pp.118-125
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• 2001

Most of the laws and standards relevant to technology in Korea bear a resemblance to those in Japan. Electricity was not introduced to Korea until Lighting ceremony in Kyong-Bok palace observed in 1887. Since Korea was annexed to Japan in 1910 and our public works were under Japan control we have applied Japanese laws and regulations made by Chosun government-general. Independently from Japan the power electricity accepted power plants of USA, codes of NESC, ASME / ANSI, NEMA. Our generation and distribution system takes American style while our consumer side takes Japanese style. As global trade system was transferred GATT into WTO, the harmonization of technological standards, certification construction testing in the trend of world. This paper is based on WTO / TBT agreement coming in effect after 12th, April, 1979. For Korea the distribution system has a strong resemblance to American system so that unconvertible because IEC 60364 originated from Europe while NEC originated from USA. This papers deals with the fundamental elements of electrical safety system with comparing IEC 60364 with NEC. This paper considers how engineers should apply NFPA 70(NEC) and IEC based on the comparison of NEC to IEC in relation to electrical installations.

• Annual Conference of KIPS
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• 2014.04a
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• pp.368-371
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• 2014

최근 디지털계측제어시스템은 사이버위협에 매우 취약하여 사이버공격에 의해 발전소 안전에 부정적인 영향을 받을 수 있는 실정이다. 따라서 디지털계측제어시스템에 대해 주기적인 사이버보안 위험 평가가 필요하다. 이에 따라 본 논문에서는 테스트베드 구축을 통해 특정 시점에서의 사이버 위협의 침해 가능성 분석, 또는 자체적으로 사이버보안성을 평가할 수 있는 방법에 대해 제안한다. 동 연구에서 제안하는 사이버보안 위험 평가는 자산분석, 테스트베드 구축, 취약점 분석, 위협평가, 위험도분석 및 평가 총 5단계로 구성되며 각 단계의 사이버보안 활동 수행을 통해 디지털계측제어계통의 사이버보안수준이 향상될 것으로 사료된다.

• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.3
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• pp.129-137
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• 1999

Reinforced concrete structures using early age concrete were result in the degradation of structural performance due to crack, overload, unexpected vibration and impact load. It demands urgently that reinforced concrete structure using early age concrete should be improved the serviceability and structural performance with the application of new fiber materials. Therefore specimens, designed by the test varibles, such as with or without stirrup and percent of steel fiber incorporated, were constructed and tested to evaluate and develop the structural performance of reinforced steel fiber concrete beam. Based on the test results reported in this study, the following conclusions are made. Specimens, designed by the over 0.75% of steel fiber incorporated, were showed the ductile behavior and failed slowly with flexure and flexure-shear. Comparing with the load-displacement relationship of specimen BSS, designed by the recommendations of the Ministry of Construction and Transportation, reinforced steel fiber concrete beam using early age concrete, over 0.75% of steel fiber incorporated, gets enough load carrying capacity and ductility. Increasing the percent of steel fiber incorporated(0.25~2.0%), the ultimate shear stress of each specimen were increased 12~40% than that of control specimen SSS.

• Journal of Drive and Control
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• v.12 no.3
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• pp.25-35
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• 2015

The hydraulic power-take-off mechanism (HPTO) is one of the most popular methods in wave energy converters (WECs). However, the conventional HPTO with only one direction motion has a number of drawbacks that limit its power capture capability. This paper proposes an adjustable moving angle wave energy converter (AMAWEC) and investigates the effect of the moving angle on the performance of the wave energy converter to find the optimal moving angle in order to increase the power capture capability as well as energy efficiency. A mathematical model of components from a floating buoy to a hydraulic motor was modeled. A small scale WEC test rig was fabricated to verify the power capture capability and efficiency of the proposed system through experiments.

• Journal of Drive and Control
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• v.13 no.1
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• pp.43-48
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• 2016

This paper presents a preliminary study on the pressure sensing characteristics of smart nano composites made of MWCNT (multi-walled carbon nanotube) to develop a novel pressure sensor. We fabricated the composite pressure sensor by using a solution casting process. Made of carbon smart nano composites, the sensor works by means of piezoresistivity under pressure. We built a signal processing system similar to a conventional strain gage system. The sensor voltage outputs during the experiment for the pressure sensor and the resistance changes of the MWCNT as well as the epoxy based on the smart nano composite under static pressure were fairly stable and showed quite consistent responses under lab level tests. We confirmed that the response time characteristics of MWCNT nano composites with epoxy were faster than the MWCNT/EPDM sensor under static loads.

• Journal of Drive and Control
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• v.13 no.2
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• pp.42-50
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• 2016

The conventional technique to measure the hysteresis and the null of servo valves is defined in ISO 10770-1 and based on load flow signal of the servo valve. A new technique based on the transmission line pressures is suggested in this study. The new measuring method was verified through a series of experiments. No hysteresis was observed between the spool displacement and the transmission line pressures, load pressure or each chamber pressure. Some hysteresis was observed between valve input and pressures, which was found to be the same as those of load flow and spool displacement for the valve input. By using the chamber pressures, the hysteresis and the null are easier to measure than the load pressure or differential pressure between those two chamber pressures because the chamber pressures showed sharp edges.

• Journal of Drive and Control
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• v.11 no.2
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• pp.22-29
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• 2014

This paper presents simulation-based analysis of energy flow of a wheel loader. The objective of this study is to analyze the energy flow of a wheel loader during driving and working. Because the wheel loader powertrain consists of a mechanical and hydraulic powertrain, the generated power from the engine is divided into 2 powertrains. Further, a virtual prediction of energy flow in the powertrains is a key factor in terms of optimal design. Accordingly, the simulation model that is able to predict the virtual energy flow is developed and analyzed in this study. The proposed wheel loader simulation model has been constructed in the Matlab/Simulink environment. It is expected that the developed simulation model will analyze the energy flow and efficiency in the design stage.

• Journal of Drive and Control
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• v.11 no.3
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• pp.14-21
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• 2014

The goal of this study drifter is to understand the operating mechanism of a drifter and to suggest a reliable analysis model which can be used for evaluating the drifter's performance from the viewpoint of impact frequency and energy. For this, the working principle of drifter and functions of its main components were analyzed, and a simulation model was developed based on the analysis. The model was validated using experimental tests on a test-bench. A comparative study of simulation and experimental results indicated that the suggested model accurately represents the real drifter system in terms of impact frequency and impact energy per blow.