• 제목/요약/키워드: Hot Working

검색결과 321건 처리시간 0.027초

The Effects of Seasons (Hot/Dry and Cool/Humid) on Thermoregulatory Responses of Male and Female Bali-Cattle Working in the Field

  • Kasa, I.W.;Hill, M.K.;Thawites, C.J.;Baillie, N.D.
    • Asian-Australasian Journal of Animal Sciences
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    • 제10권1호
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    • pp.64-69
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    • 1997
  • A study was conducted on the effects of ploughing on physiological responses of male and female Bali-cattle. A $2{\times}2{\times}6{\times}8$ factorial design (2 seasons, 2 sexes, 6 days and 8 consecutive time of measurements every 30 minutes) was employed. Responses during the cool/humid season were lower than hot/dry; respiration rate (RR) was 52 vs 75/min, rectal temperature(RT) was 39.1 vs $39.5^{\circ}C$ and skin temperature (ST) was 37.1 vs $37.6^{\circ}C$. Within sexes, males were less tolerant than females in that their RR (66 vs 61 breath/min), RT (39.4 vs $39.2^{\circ}C$) and ST (37.6 vs $37.1^{\circ}C$) were each higher than females during work. With increasing time, during the average 2.5 h working period gradual increases in RR, RT and ST were recorded and the overall increases of 84 breath/min, $1.9^{\circ}C$ and $13.8^{\circ}C$ respectively (p < 0.001). Packed cell volume (PCV) data indicated significant difference between sexes, time and season (p < 0.001, p < 0.05 and p < 0.001 respectively). Within time (before and after 2.5 h working) the PCV decreased from 27.4 to 25.6%.

유속에 따른 열선의 과열비 조정을 통한 열선유속계의 감도향상에 관한 연구 (Sensitivity Enhancement of a Hot-Wire Anemometer by Changing Overheat Ratio with Velocity)

  • 이신표;고상근
    • 대한기계학회논문집
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    • 제19권10호
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    • pp.2678-2689
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    • 1995
  • In this study, a new hot-wire anemometer which has greater sensitivity than that of a constant temperature anemometer (CTA) was proposed. In contrast to CTA, the wire working resistance of the new anemometer increases with flow velocity, that is, the operating mode of the wire becomes variable temperature. The variable temperature anemometer(VTA) was made by substituting a voltage controlled variable resistor such as photoconductive cell or transistor for one of the resistors in the bridge. By positively feeding back the bridge top signal to the input side of these electronic components, the wire overheat ratio could be increased with velocity automatically. Static response analyses of the VTA, constant voltage anemometer (CVA) and CTA were made in detail and calibration experiments were performed to validate the proposed operating principle. The wire operating resistance of the CVA decreases with velocity and this leads to lower sensitivity than that of a CTA. But the sensitivity of the newly proposed VTA is superior to that of a CTA, since the wire overheat ratio increases with velocity. Consequently, it is found that the major factor that is responsible for large sensitivity of a VTA is not the working resistance itself but the change of the wire working resistance with velocity.

스프레이 열전달을 이용한 저온도차 스털링 엔진의 고온수 공급 유량 및 온도에 따른 기계 부하성능 실험 (Mechanical Load Performance Measurements of a Low Temperature Differential Stirling Engine with Water-Sprayed Heat Transfer according to Supply Water Flow Rates and Temperatures)

  • 심규호;정민성;이윤표;장선준
    • 한국유체기계학회 논문집
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    • 제18권1호
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    • pp.29-36
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    • 2015
  • Recently, Stirling engines are emerging as a key device for power conversion of renewable energy or waste energy. This study develops a LTDSE(Low Temperature Differential Stirling Engine) using a water spray for higher heat transfer and performs load performance tests for various flow rates and temperatures of hot water spray for variable engine loads emulated by a mechanical friction device. Internal temperature and pressure, working frequency and inlet and outlet temperature of the supply water are measured. As a result, the increases in flow rate and temperature of hot water respectively enhance the power output, efficiency and the working frequency, while the increasing engine load leads to decreases in working frequency but increases in the pressure amplitude. Eventually, it is revealed there exists a maximum shaft power of the test engine.

스테인리스-아세톤 히트파이프의 열전달 특성에 관한 실험적 연구 (An Experimental Study on the Heat Transfer Characteristics of Stainless-Acetone Heat Pipe)

  • 강금춘;김영중;유영선;백이;이건중
    • Journal of Biosystems Engineering
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    • 제25권6호
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    • pp.489-496
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    • 2000
  • This study was conducted in order to find an ideal working fluid kind and a proper filling amount in the heat pipe as well as an inclined angle of heat pipe when they are placed to recover exhaust gas heat in the hot air heater. Followings are the findings of this research. 1. Of the four different working fluids-gasoline kerosene distilled water and acetone-acetone filled heat pipe showed the best performance giving out more homogeneous temperature profile on the radiating part than the kerosene and gasoline heat pipe an carrying out heat transmitting function better than the distilled water heat pipe by 10~2$0^{\circ}C$ higher on the radiating part. Acetone would be a good choice for recycling of exhaust gas heat in the hot air heater. 2. Of the filling amount of working fluid inside the heat pipes dry-out situations possible caused by insufficient filling were found in the filling amount of 5, 7.5 and 10% heat pipes as heat supply rate increases gradually in the range of 50 to 15kJ/sec. but no dry-out and stabilized heat transmitting performance occurred in the heat pipes of 12.5 and 15% filling at the same heat supply rate. It recommends that filling amount shall exceed 12.5% at least with the working fluids of this experiment. 3. The test revealed that the heat transmitting performance of heat pipe was more affected by filling amount rather than inclined angle.

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열간 형단조에 의한 아이들러 개발에 대한 연구 (A Study on the Development of Idler by Hot Closed-die Forging)

  • 정호승;조종래;박희천
    • 한국소성가공학회:학술대회논문집
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    • 한국소성가공학회 2003년도 춘계학술대회논문집
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    • pp.199-203
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    • 2003
  • Idler of excavator are large product with diameter 500 - 600 mm and parts of a power transmit device. The object of the paper is developed large products by hot closed-die forging. The forging process which is proposed from numerical analysis and various tests is developed a large products with good quality. To estimate the design process parameters such as working load, temperature and flash thickness so on, numerical analysis are used by DEFORM 2D. To obtain a flow stress data and optimal forging temperature is carried out hot compression and tensile test at a various temperature range. Developed product is tested mechanical properties of elongation, hardness and tensile strength so on. Test results are presented excellent mechanical properties.

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A Study on High Precision Temperature Control of an Oil Cooler for Machine Tools Using Hot-gas Bypass Method

  • Jung, Young-Mi;Byun, Jong-Yeong;Yoon, Jung-In;Jeong, Seok-Kwon
    • Journal of Advanced Marine Engineering and Technology
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    • 제33권7호
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    • pp.1003-1011
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    • 2009
  • This study aims at precise control of oil outlet temperature in the oil cooler system of machine tools for enhancement of working speed and processing accuracy. PID control logic is adopted to obtain desired oil outlet temperature of the oil cooler system with hot-gas bypass method. We showed that the gains of PID controller could be easily determined by using gain tuning methods to get the gain of PID controller without any mathematical model. We also investigated various gain tuning methods to design the gains of PID and compared each control performance for selecting the optimal tuning method on the hot gas bypass method through experiments. Moreover, we confirmed excellent control performance with proposed PI controller gain even though disturbances were abruptly added to the experimental system.

핫라인 써포트암을 이용한 완철교체공법 (The Method for Replacement of Strain Pole Crossarm using the Hot-line Support Arm)

  • 문성원;박용범;김점식;송현석;조시형;최명호
    • 한국조명전기설비학회:학술대회논문집
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    • 한국조명전기설비학회 2006년도 춘계학술대회 논문집
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    • pp.59-64
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    • 2006
  • In this paper, developed a uninterruptible hotline tools and method for replacement of strain pole crossarm on overhead distribution line. For practical use of developed tools, following direct hot-line methods were proposed: 'Direct hot-line method for replacement of pin pole crossarm', 'Direct hot-line method for alteration of crossarm' and 'Crossarm replacement method in uninterruptible cable displacement area'. These methods were proposed more simple and safe working on hotline job.

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Dead Pixel Detection Method by Different Response at Hot & Cold Images for Infrared Camera

  • Ye, Seong-Eun;Kim, Bo-Mee
    • 한국컴퓨터정보학회논문지
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    • 제23권11호
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    • pp.1-7
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    • 2018
  • In this paper, we propose soft dead pixels detection method by analysing different response at hot and cold images. Abnormal pixels are able to effect detecting a small target. It also makes confusing real target or not cause of changing target size. Almost exist abnormal pixels after image signal processing even if dead pixels are removed by dead pixel compensation are called soft dead pixels. They are showed defect in final image. So removing or compensating dead pixels are very important for detecting object. The key idea of this proposed method, detecting dead pixels, is that most of soft deads have different response characteristics between hot image and cold image. General infrared cameras do NUC to remove FPN. Working 2-reference NUC must be needed getting data, hot & cold images. The way which is proposed dead pixel detection is that we compare response, NUC gain, at each pixel about two different temperature images and find out dead pixels if the pixels exceed threshold about average gain of around pixels.