• 대한전기학회:학술대회논문집
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• 대한전기학회 2002년도 하계학술대회 논문집 C
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• pp.1710-1713
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• 2002

Recently, the pulsed power system has been used to many applications. Such as remediation of environmental hazards, food sterilization, air pollution control E/P (Electrostatic Precipitator), DeNOx/DeSOx power system, ozone generator, high energy physics, and other power source applications. A pulse energy efficiency for load depends on the rising time, peak value. Pulse duration and impedance matching etc. The pulsed power system generally required for short pulse duration and high peak value was forced to consider its volume and economy. In this paper, we investigated operating characteristics of the CO2 laser using an inductively pulsed power system.

• Tribology and Lubricants
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• 제34권2호
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• pp.43-48
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• 2018

This paper presents the thermohydrodynamic analysis of tilting journal pad bearings supporting a power turbine rotor applied to a 250 kW super-critical $CO_2$ cycle. In the analysis, the generalized Reynolds equation and 3D energy equation are solved to predict oil film temperature and the 3D heat conduction equation is solved for pad temperature. The power turbine rotor is supported by two tilting pad bearings consisting of five pads with an oil supply block between the pads. Copper backing pads with higher thermal conductivity compared to steel backing pads are adopted to improve thermal management. The predicted maximum pad temperature is around $55^{\circ}C$ which is approximately $15^{\circ}C$ higher than oil supply temperature. In addition, the predicted minimum film thickness is 50 mm at a rotating speed of 5,000 rpm. These results indicate that there is no issue in the thermal behavior of the bearing. An operation test is performed with a power turbine module consisting of a power turbine, a reduction gear and a generator. Thermocouples are installed at the 75% position from the leading edge of the pad to monitor pad temperature. The power turbine uses compressed air at a temperature of $250^{\circ}C$ in its operation. The steady state pad temperatures measured in the test show good agreement with the predicted temperatures.

• 한국기계가공학회지
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• 제17권3호
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• pp.45-50
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• 2018

From the flow analysis of the silencer for 8 kW diesel generators, the following results were obtained. For silencer-1, it was confirmed that the holes formed at the inlet-side portion connect into the exhaust pipe in the chamber. The exhaust pipe installed inside silencer-1 was integrally connected through the holes in the chamber. As a result, it was confirmed that the pressure inside the chamber was kept stable. It was confirmed that the pressure loss generated inside an absorptive type silencer such as silencer-2 was small. The differential pressure of the inlet-outlet of silencer-1 and silencer-2 was confirmed to be 494 Pa at 15 m/s, 859 Pa at 20 m/s, 1326 Pa at 25 m/s, and 1911 Pa at 30 m/s.

• 한국정보통신학회논문지
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• 제17권8호
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• pp.1842-1850
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• 2013

ETSI 표준 M2M 플랫폼은 M2M을 위한 공통 서비스를 제공하는 플랫폼으로, 본 논문에서는 WSDL 2.0 표준 문서를 이용하여 ETSI 표준 M2M 플랫폼 서비스를 SOAP, HTTP 및 CoAP 형태의 웹 서비스로 제공 가능하게 함으로 서비스 차원에서 이종의 웹 애플리케이션과 연동하기 위한 방안을 제시하고 있다. 본 논문에서 제안하는 서비스 차원의 통합 방안은 (1) M2M 플랫폼의 서비스 인터페이스를 WSDL 2.0 문서로 기술하는 단계, (2) 제시된 웹 클라이언트 생성기에 따라 WSDL 2.0 문서를 토대로 SOAP, HTTP 및 CoAP 웹 클라이언트를 생성하는 단계, (3) 제시된 웹 프로토콜 변환기로 웹 서비스 실행 시 이종의 프로토콜을 상호 변환하여 주는 단계를 포함하고 있다.

• 대한방사선기술학회지:방사선기술과학
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• 제18권2호
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• pp.49-59
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• 1995

Recently, general radiography became to variety because of the continuous development of Inverter type generator and ortho chromatic system. Therefore, we must re-evaluate about patient exposure dose and image quality. I studied about chest radiography which has frequency among general radiography being used during FEB. to AUG., 1994 over 151 medical facilities from medical facilities that are located in Seoul area. The result obtained were as follows ; 1) The rectification method of the generator were employing mainly single phase full wave in 82.8 %, three phase full wave in 11.26 % and Inverter type in 4.64 % and condenser type is 1.32 %. 2) Exposure kV was used below 80 kV in most medical facilities and 21.8 % of the medical facilities was using high tube voltage higher than 120 kV. 3) The exposure time was used below the 0.05 sec in 28.4 %, in 29.8 % of the medical facilities used above 0.1 sec. 4) The usage frequency of the added filter is 15.3 %, and among them compound filter was used only 4 %. 5) Rare earth screen was used in 37.7 %. 6) The average skin entrance dose was 0.25 mSv, the range of dose is $0.05{\sim}0.79\;mSv$ in each medical facilities. 7) The average density of the lung field is 1.76, 0.49 in lung side, 0.30 in mediastinum and 0.37 in heart shadow. Therefore it is required to improve all of these for increasing image quality and reducing patient exposure dose as soon as possible.

• 설비공학논문집
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• 제25권2호
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• pp.55-63
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• 2013

For a large-scale semiconductor manufacturing clean room, the energy consumed in an outdoor air conditioning system to heat, humidify, cool and dehumidify incoming outdoor air is very large. In particular, the energy requirement to humidify outdoor air in the winter season is generally known to be high. Recently, in order to overcome the high energy consumption nature of a steam generator in a conventional steam humidification type outdoor air conditioning system, an air washer is often introduced instead of the steam generator in the outdoor air conditioning system, which can be called a water spray humidification type outdoor air conditioning system. Therefore, the assessment and comparison of the annual energy consumed in the steam humidification type and the water spray humidification type outdoor air conditioning systems deserves to be examined in order to reduce the outdoor air conditioning load of a clean room. In the present study, a numerical analysis was conducted to obtain the annual electric power consumption of the two outdoor air conditioning systems. It was shown from the comparison of the numerical results that the water spray humidification type outdoor air conditioning system can reduce about 30% of annual electric power consumption of the steam humidification type outdoor air conditioning system.

• 한국소음진동공학회논문집
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• 제25권9호
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• pp.599-605
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• 2015

U.S. Nuclear Regulatory Commission(NRC), Regulatory Guide(RG) 1.20(Rev.3, 2007년)은 원자로 냉각재계통, 주증기, 주급수 및 복수시스템의 주요 배관 및 기기에 대하여 압력변동 및 진동에 의한 잠재적 유해효과에 대한 평가를 요구한다. 그러나 증기발생기와 연결된 주증기, 주급수 및 복수시스템의 주요 배관 전체에 대하여 상세 해석하는 것은 매우 복잡하여 한계가 있다. 이 논문은 APR1400 원전의 종합진동평가(comprehensive vibration assessment program, CVAP)를 수행하기 위하여 증기발생기에 연결된 2차측 주요 배관의 음향공진과 펌프유발진동을 위한 간이평가 방법에 관한 것이다. 이 논문에서는 이러한 배관시스템의 잠재적 진동 원인이 무엇인지, 음향공진과 펌프유발진동의 가능성을 예방하기 위한 간이평가 방법은 무엇인지를 고찰하고자 한다. 이 논문은 APR1400 원전 증기발생기와 연결된 주증기 및 주급수 배관의 유동유발진동 간이평가를 위해 사용될 것으로 판단된다.

• 한국산학기술학회논문지
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• 제10권4호
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• pp.695-701
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• 2009

고압의 가스를 이용하여 고온 가스와 저온 가스를 분리하거나 입자상 물질의 분리에 사용 할 수 있는 장치인 볼텍스 튜브의 에너지 분리 특성을 적용하여 $CO_2$ 흡수를 위한 장치설계의 기본 설계 자료를 구축하기 위하여 전산유체 해석을 수행하였다. 설계를 위한 기초 자료를 확보하기 위하여, 볼텍스 튜브의 길이, 볼텍스 발생기의 오리피스 직경 및 고온 측과 저온 측의 유량비등이 볼텍스 튜브의 성능에 미치는 영향을 분석하였다. 튜브의 길이가 길어짐에 따라 고온 출구측의 온도는 감소하지만, 저온 출구측의 온도에 미치는 영향은 미미하였다. 볼텍스 발생기의 오리피스 직경이 축소됨에 따라 저온측 온도는 강하하나 고온측 온도의 변화는 미미하였다. 고온 유량비가 증가함에 따라 고온 출구 쪽의 온도가 강하하였다. 본 연구의 결과는 $CO_2$ 흡수 장치의 기본 설계 자료로 응용될 수 있을 것이다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2004년도 하계학술대회 논문집 B
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• pp.1118-1120
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• 2004

For the first time in Korea, a 100hp high Tc superconducting(HTS) motor has been designed, developed and successfully tested recently. The design was based on 2-dimensional electromagnetic field analysis of cylindrical coordinate. The field winding of rotor was wound with Bi-2223 tapes and tested after assembled with other rotor components. The stator had air-gap type armature windings which allow higher terminal voltage and more sinusoidal voltage waveform than conventional iron cored machines. Steady state open & short-circuit test and resistive load test were conducted also in generator mode. The fabrication and test results of this machine were discussed in this paper.

• Tribology and Lubricants
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• 제33권2호
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• pp.65-70
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• 2017

In vertical hydro/hydraulic power turbine-generator applications, traditionally, cylindrical turbine guide bearings (TGBs) are widely used to provide turbine runner shafts with smooth rotation guides and supports. All existing cylindrical TGBs with simple plain pads have drawbacks such as having no pressure generation and film stiffness at the no-load condition and in addition, at the low-load/low-eccentricity condition, having very low film stiffness values and lacking design credibility in the stiffness values themselves. In this paper, in order to fundamentally improve the low-load/low-eccentricity performance of conventional cylindrical TGBs and thus enhance their design-application availability and usefulness, we propose to introduce a rotation-directional leading-edge taper to each partitioned pad, i.e., a pad leading-edge taper. We perform a design analysis of lubrication performance on $4-Pad{\times}4-Row$ cylindrical TGBs to verify an engineering/technical usefulness of the proposed pad leading-edge taper. Analysis results show that by introducing the leading-edge taper to each pad of the cylindrical TGB one can expect a constant high average direct stiffness with a high degree of design credibility, regardless of load value, even at the low-load/low-eccentricity condition and also control the average direct stiffness value by exploring the taper height as a design parameter. Therefore, we conclude that the proposed pad leading-edge tapers are greatly effective in more accurately predicting and controlling rotordynamic characteristics of vertical hydro-power turbine-generator rotor-bearing systems to which cylindrical TGBs are applied.