• 제목/요약/키워드: Thermal condition

검색결과 3,159건 처리시간 0.029초

알루미늄 판 표면에 용사된 Al/SiC의 마모 거동 (Wear Behavior of Al/SiC in Thermal Spray Process)

  • 김형자;유만희;이성호;이광진
    • 동력기계공학회지
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    • 제10권2호
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    • pp.111-116
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    • 2006
  • Tribologcal property of the ceramics used in severe condition was investigated and both $Al_2O_3$ ball and Al/SiC composite made by thermal spray process[TSP] were used as a specimen in this study. Four kinds of material couple in ball and disk specimens were tested in the dry condition by using ball-on-disk type tribo-tester. Friction coefficient, surface roughness, wear rate, and photograph of the worn surface were investigated. Generally, High SiC contents[$40{\sim}50%$] specimens showed very low friction coefficient below 0.05 and little wear rate in dry condition. And also, low SiC contents[0%] specimens showed a moderate wear rate and high coefficient of friction at the same condition.

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고속 운전조건을 고려한 하이브리드 자동차용 ISG 모터 방열설계 및 해석 평가 (Thermal Design and Analysis Evaluation of ISG Motor for Hybrid Electric Vehicles considering High-speed Driving Condition)

  • 김성철
    • 한국자동차공학회논문집
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    • 제22권1호
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    • pp.59-64
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    • 2014
  • Integrated Starter Generator (ISG) system improves the fuel economy of hybrid electric vehicles by using idle stop and go function, and regenerative braking system. To obtain the high performance and durability of ISG motor under continuously high load condition, the motor needs to properly design the cooling system (cooling fan and cooling structure). In this study, we suggested the enhanced design by modifying the thermal design of the ISG motor and then analyzed the improvement of the cooling performance under high-speed condition and generating mode by CFD simulation. The temperatures at the coil and the magnet of the enhanced model were decreased by about $4^{\circ}C$ and $6^{\circ}C$, respectively, compared to those of the conventional model. Therefore, we verified the cooling performance enhancement of the novel thermal design in the case of core loss increment due to the higher speed condition.

열환경챔버의 냉방 시뮬레이션 프로그램 개발에 관한 연구 (A Study on the Development of Cooling Simulation Program for Thermal Environmental Chamber)

  • 이한홍
    • 한국생산제조학회지
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    • 제8권5호
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    • pp.108-114
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    • 1999
  • The thermal environmental chamber has been using in maintaining weather condition keeping thermal capacity under heating and cooling load fluctuation and for the performance testing of cooling system or air-conditioner on artificial envi-ronment. In ordder to make the various environmental conditions in the thermal environmental chamber the proper cooling system is necessary to eliminate the heating load produced inside the chamber and to maintain the designed environmental condition. For this reason the optimal design of cooling system and the prediction of performance is also required. This paper describes the prediction of performance of cooling system in the thermal environmental chamber with the capacity of 37,000kcal/hr which is developed for the test of performance in heating mode of heat pump system, In the results this paper is trying to develop simulation program on the base of mathematical models and which can be applied effectively to the optimal design of cooling system and prediction of performance to the inside and outside change of envi-ronmetal load.

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에어컨디션에서 카펫의 열안정성에 관한 연구 (A Study on the Thermal Stability of Carpet in Air Condition)

  • 박근호;이수;송주영;이기철
    • 한국응용과학기술학회지
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    • 제23권4호
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    • pp.362-367
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    • 2006
  • This paper describes the experiments for investigating the effects of thermal stability of several commercial carpet mate materials. The melting point and thermal decomposition temperature was measured by means of a differential scanning calorimeter(DSC) in air condition. The DSC data and burning test results of nylon bulked continuous filament(N-BCF) yarn 100%, nylon(NY), polypropylene(PP), and a new material named polytrimethyleneterephthalate(PTT) were analysed to obtain the effect on their thermal stability. Conclusively, we observed that PTT and PP were approximately $380^{\circ}C$ and $240^{\circ}C$ to start the thermal decomposition, respectively. In other words, PTT is thermally the most stable material for carpet manufacturing.

다목적실용위성 2호 추진계의 열설계 (Thermal Design for KOMPSAT-2 Propulsion System)

  • 한조영;김정수;이균호
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2001년도 추계학술대회논문집B
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    • pp.77-82
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    • 2001
  • Thermal design for KOMPSAT-2 propulsion system has been performed. Overall design requirements and the constitution for propulsion system is described. To meet the thermal design requirements, both a primary and a redundant heater circuit, each with two thermostats placed in series, will protect each hydrazine-wetted components, even if one heater circuit fails to operate. Heater power is turned off if any one of these thermostats is opened at its higher setpoint. Thus, even if one thermostat is failed closed, the second thermostat will turn off the heater. All such components shall be insulated with MLI. Propulsion heater sizing based on the constant worst cold case condition is conducted through thermal analysis. All heaters selected for propulsion components operate to prevent propellant freezing satisfying the thermal requirements for the propulsion subsystem over the worst case average voltage, i.e. 25 volts.

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정지궤도 위성의 열평형 시험 모델링 및 예비 예측 (THERMAL BALANCE MODELLING AND PREDICTION FOR A GEOSTATIONARY SATELLITE)

  • 전형열;김정훈
    • 한국전산유체공학회:학술대회논문집
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    • 한국전산유체공학회 2009년 춘계학술대회논문집
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    • pp.142-147
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    • 2009
  • COMS (Communication, Ocean and Meteorological Satellite) is a geostationary satellite and has been developing by KARI for communication, ocean and meteorological observations. It will be tested under vacuum condition and very low temperature in order to verify thermal design of COMS. The test will be performed by using KARI large thermal vacuum chamber, which was developed by KARI, and the COMS will be the first flight satellite tested in this chamber. The purposes of thermal balance test are to correlate analytical model used for design evaluation and predicting temperatures, and to verify and adjust thermal control concept. KARI has plan to use heating plates to simulate space hot condition especially for radiator panels such as north and south panels. They will be controlled from 90K to 273K by circulating GN2 and LN2 alternatively according to the test phases, while the shroud of the vacuum chamber will be under constant temperature, 90K, during all thermal balance test. This paper presents thermal modelling including test chamber, heating plates and the satellite without solar array wing and Ka-band reflectors and discusses temperature prediction during thermal balance test.

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복합열전달과 열경계조건에 관한 연구 (Investigation of the Conjugate Heat Transfer and Wall Thermal Boundary Conditions)

  • 장병훈
    • 대한기계학회논문집B
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    • 제23권1호
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    • pp.33-42
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    • 1999
  • The effects of wan thermal boundary condition were investigated for a uniform wall temperature, a uniform wall heat flux, and for coupled heat conduction In the channel wall with transverse rectangular ribs. Numerical investigations for steady laminar flow show behavior similar to that observed experimentally in the separated flow region for flow over a cylinder. Conjugate heat transfer with a low solid-fluid thermal conductivity ratio does not lead to the same results as for the uniform heat flux boundary condition, and heat transfer reversal is found on the back sides of the ribs.

비선형성 해석에 의한 화력발전소 터어빈 제어계통에 관한 연구 (The improvement of control strategy in thermal power plant turbine system by nonlinear analysis)

  • 황재호;이정준
    • 제어로봇시스템학회:학술대회논문집
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    • 제어로봇시스템학회 1989년도 한국자동제어학술회의논문집; Seoul, Korea; 27-28 Oct. 1989
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    • pp.567-571
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    • 1989
  • This paper describes the improvement of thermal power plant turbine control system by analyzing nonlinear characteristics. The turbine control depends on the frequency variation and boiler condition. The nonlinearity of turbine control is the result of governor/valve properties, steam condition and boiler thermal unbalance. Nonlinear analysis is divided into two; main steam valve position - turbine output anal governor response. Of course, every analysis must be done on considering plant operating condition. In this paper, after analyzing turbine control nonlinearity by numerical method and actual results, the sensitive operating load which corresponds to frequency is proposed, on guarranteed boiler stability. This idea is implemented at Pyung Tack thermal power plant, and the practical results are showed.

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초고속 스핀들의 윤활조건 선정을 위한 기초 연구 (A Foundation Study on the Selection of Bearing Lubrication Conditions in High-speed Spindle)

  • 안성환;이춘만
    • 한국기계가공학회지
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    • 제8권1호
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    • pp.3-9
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    • 2009
  • Recently, a high speed cutting is essential requirement to satisfy latest demand of high precision product and machining of hard materials. However heat generation by high speed rotation causes many problems. The machining error and shortening spindle lifetime by thermal stress is typical example. Generation of heat is mostly caused by sliding at the rotor and bearing. For minimization of heat generation at bearing, decision of the condition of proper lubrication is necessary. The thermal study about 40,000rpm spindle by changing the condition of oil-air lubrication method is carried out in this paper. The results of this paper can be used effectively in the decision of oil-air lubrication condition of other types of spindle for machine tools.

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복합응력이 작용하는 균열 배관에 대한 천이 크리프 조건에서의 C(t)-적분 예측 (I) - 탄성-크리프 - (Estimations of the C(t)-Integral in Transient Creep Condition for Pipe with Crack Under Combined Mechanical and Thermal Stress (I) - Elastic-Creep -)

  • 송태광;김윤재
    • 대한기계학회논문집A
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    • 제33권9호
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    • pp.949-956
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    • 2009
  • The C(t)-integral describes amplitude of stress and strain rate field near a tip of stationary crack under transient creep condition. Thus the C(t)-integral is a key parameter for the high-temperature crack assessment. Estimation formulae for C(t)-integral of the cracked component operating under mechanical load alone have been provided for decades. However, high temperature structures usually work under combined mechanical and thermal load. And no investigation has provided quantitative estimates for the C(t)-integral under combined mechanical and thermal load. In this study, 3-dimensional finite element analyses were conducted to calculate the C(t)-integral of elastic-creep material under combined mechanical and thermal load. As a result, redistribution time for the crack under combined mechanical and thermal load is re-defined through FE analyses to quantify the C(t)-integral. Estimates of C(t)-integral using this proposed redistribution time agree well with FE analyses results.