• 전기저널
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• 5호통권161호
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• pp.9-13
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• 1990

• Bulletin of the Korean Chemical Society
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• 제32권5호
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• pp.1630-1634
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• 2011

Electroless plating of metallic nickel on carbon fiber surfaces was carried out to control specific electric resistivity of the fibers, and the effects of the nickel content and coating thickness on the electric properties were studied. The structural and surface properties of the carbon fibers were characterized using X-ray diffraction (XRD), scanning electron microscopy (SEM), and X-ray photoelectron spectroscopy (XPS). The specific resistivity of the fibers was measured using a four-point probe testing method. From the XPS results, the oxygen and Ni atomic ratio of the fibers was greatly enhanced as the plating time increased. Additionally, it was observed that the specific electric resistivity decreased considerably in the presence of metallic nickel particles and with the formation of nickel layers on carbon fibers.

• 제어로봇시스템학회논문지
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• 제22권7호
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• pp.552-556
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• 2016

Obstacle detection is a key feature in the safe driving control of electric wheelchairs. The suggested obstacle detection algorithm was designed to provide obstacle avoidance direction and detect the existence of cliffs. By means of this information, the wheelchair can determine where to steer and whether to stop or go. A 3D depth camera (Microsoft KINECT) is used to scan the 3D point data of the scene, extract information on obstacles, and produce a steering direction for obstacle avoidance. To be specific, ground detection is applied to extract the obstacle candidates from the scanned data and the candidates are projected onto a 2D map. The 2D map provides discretized information of the extracted obstacles to decide on the avoidance direction (left or right) of the wheelchair. As an additional function, cliff detection is developed. By defining the "cliffband," the ratio of the predefined band area and the detected area within the band area, the cliff detection algorithm can decide if a cliff is in front of the wheelchair. Vehicle tests were carried out by applying the algorithm to the electric wheelchair. Additionally, detailed functions of obstacle detection, such as providing avoidance direction and detecting the existence of cliffs, were demonstrated.

• Journal of Biosystems Engineering
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• 제40권3호
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• pp.250-260
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• 2015

Purpose: Dual cylindrical microwave chambers equipped with an ohmic heating tube were designed and fabricated to maximize the electric field strength for expeditious heat treatment of particulate foods. Methods: The efficacy of the combination heater was investigated by simulating the electric field distribution by using COMSOL Multiphysics software. Results: All components of the designed microwave heating unit were suitable for transmitting maximal microwave power to the load. The simulated electric field distribution implied that single-mode microwave heating would be sufficient for the steady generation of a highly localized heating zone in the cavity. During impedance matching, the calculated reflection coefficient ($S_{11}$) was small, possibly implying minimal power loss and wave reflection in the designed microwave heating chamber. Conclusions: This study demonstrates the possibility of concentrating the microwave power at the centerline for a single-frequency microwave, for thermal treatment of multiphase foods without attenuating the microwave power.

• International Journal of Fluid Machinery and Systems
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• 제3권1호
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• pp.58-66
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• 2010

A steam control valve is used to control the flow from the steam generator to the steam turbine in thermal and nuclear power plants. During startup and shutdown of the plant, the steam control valve is operated under a partial flow conditions. In such conditions, the valve opening is small and the pressure deference across the valve is large. As a result, the flow downstream of the valve is composed of separated unsteady transonic jets. Such flow patterns often cause undesirable large unsteady fluid force on the valve head and downstream pipe system. In the present study, various flow patterns are investigated in order to understand the characteristics of the unsteady flow around the valve. Experiments are carried out with simplified two-dimensional valve models. Two-dimensional unsteady flow simulations are conducted in order to understand the experimental results in detail. Scale effects on the flow characteristics are also examined. Results show three types of oscillating flow pattern and three types of static flow patterns.

• 전기의세계
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• 제17권3호
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• pp.39-42
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• 1968

We have been studying on the discharged phenomena if compound dielectrics for insulator which is very important in electric machinery and et al. In this paper we come to the couclusion that as a result of studying on the electric design of Ozonizer, the higher frequency becomes the better output could be got, and then discharge power could be the greatest by selecting the distance of the discharge gap and atomospheric pressure properly under the same applied voltage, and that power factor of the Ozonizer reached the maximum power at a particular frequency when the discharge power is maintained at constant.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 학술대회 논문집 정보 및 제어부문
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• pp.547-549
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• 2004

This system is monitors the degree of aging happened at the electric machine. It detects electromagnetic wave generated from the insulator when the voltage is applied to the machine. By analyzing the internal and external factors make the electric, mechanic, or thermal characteristics of the electric machinery deteriorate the electric insulation and eventually cause the partial electric discharge. The continuous partial electric charge accelerates the insulation aging and the insulation breakdown happens at last. This system consists of the relays connected with 10 sensors (40 total) detecting the partial electric discharge ans the temperature, the server, ans the program analyzing and storing the data.

• Journal of Biosystems Engineering
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• 제27권1호
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• pp.51-58
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• 2002

The goal of this research was to an optimum conditions for the brown rice conditioning from data of milling characteristics after conditioning of the brown rice. The range of the initial moisture content of the sample was 13%, 14%, and 15%, the range of the increment of the moisture content was 0.4% and 0.8% with respect to the initial moisture content, and a ripe time after conditioning was eight hours. The results obtained from this research can be summarized as fellows. 1 The crack ratio after conditioning the brown rice with the initial moisture content was increased as the initial moisture content decreased and increment of the moisture content increased. The crack ratio of the milled rice was increased than that of the non-conditioned brown rice and decreased with the conditioned brown rice with the increment of the moisture content of 0.4% and 0.5%. 2. The broken rice ratio after conditioning the brown rice with the initial moisture content was a little higher than that of the non-conditioned brawn rice. The broken ratio of the conditioned brown rice with the increment of the moisture content of 0.4% was increased around 0.2∼0.4% with respect to the non-conditioned brown riced and the broken ratio of the brown rice was high with increased amount of water sprayed during conditioning process. 3. The moisture content of the milled rice after conditioning the brown rice with the initial moisture content increased around 0.3∼0.8% with respect to the non-conditioned milled rice. 4. The electric energy consumption on milling process with the conditioned brown rice by the initial moisture content was decreased 3.4∼39.1% with respect to the non-conditioned brown rice.

• 한국재료학회지
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• 제9권12호
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• pp.1188-1195
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• 1999

알루미노실리케이트 계 졸이 지르콘 쉘 몰드의 뮬라이트 층 생성에 미치는 영향을 고찰하였다. 알루미노실리케이트 졸은 콜로이달 실리카와 수용성 질산알루미늄을 혼합하여 제조하였으며 50$^{\circ}C$에서 48시간 조건에서 겔화 하였다. 이러한 겔은 깁사이트 및 알루미노실리케이트 복합 겔로 구성되어 있었으며, Si 이온과 결합하는 모든 Al 이온의 배위수가 4임을 확인하였다. 뮬라이트 상은 1300$^{\circ}C$ 이상에서 소결하였을 때 관찰되었으며 뮬라이트의 XRD 피크는 소결 온도와 질산알루미늄의 농도가 증가할수록 노실리케이트 졸 슬러리를 2차 층에 코팅하였다. 그 결과 1차 및 3차 층의 분리가 일어났으며, 이는 소결시 졸의 1차 및 3차 층으로 침윤 발생과 잔류 실리카와 뮬라이트 간의 열팽창계수 차이에 기인한 것으로 판단된다.

• 한국초전도ㆍ저온공학회논문지
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• 제17권3호
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• pp.57-61
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• 2015

A Superconducting Fault Current Limiter is an electric power device which limits the fault current immediately in a power grid. The SFCL must be cooled to below the critical temperature of high temperature superconductor modules. In general, they are submerged in sub-cooled liquid nitrogen for their stable thermal characteristics. To cool and maintain the target temperature and pressure of the sub-cooled liquid nitrogen, the cryogenic cooling system should be designed well with a cryocooler and coolant circulation devices. The pressure of the cryostat for the SFCL should be pressurized to suppress the generation of nitrogen bubbles in quench mode of the SFCL. In this study, we tested the performance of the cooling system for the prototype 154 kV SFCL, which consist of a Stirling cryocooler, a subcooling cryostat, a pressure builder and a main cryostat for the SFCL module, to verify the design of the cooling system and the electric performance of the SFCL. The normal operation condition of the main cryostat is 71 K and 500 kPa. This paper presents tests results of the overall cooling system.