• Title/Summary/Keyword: Cooling Time

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Characteristic of Cold-Weather Concrete by the Variation of Compressive Strength (강도 변화에 따른 한중콘크리트 특성연구)

  • 신성우;김인기;안종문
    • Proceedings of the Korea Concrete Institute Conference
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    • 1995.04a
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    • pp.154-159
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    • 1995
  • Cold weather concrete presents the many characteristic variation of quality, according to the mixing and cooling point, the cooling time and the quantity of air besides the compressive strength of concrete. Thus, in this study to verify the character of cold-weather concrete we make the concrete specimens at laboratory and cool them at cooling-melting machine and then test the 7days compressive strength of them, with the variation of compressive strength of concrete, cooling point, cooling time, cooling weather and air quantity. At the results, the compressive strength of concrete decrease in the case of early cooling point, long cooling time, low cooling temperature and the low design compressive strength

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A Study on the Estimation of Temperature, Humidity and Cooling Load (온도, 습도 및 냉방부하 예측에 관한 연구)

  • Yoo, Seong-Yeon;Han, Seung-Ho;Lee, Je-Myo;Han, Kyou-Hyun;Noh, Kwan-Jong
    • Proceedings of the SAREK Conference
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    • 2006.06a
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    • pp.80-85
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    • 2006
  • The peak demand of electricity in summer season mainly comes from the day time cooling loads. Ice thermal Storage System (ITSS) uses off-peak electricity at night time to make ice for the day time cooling. In order to maximize the use of cold storage in ITSS, the estimation of day time cooling load for the building is necessary. In this study, we present a method of cooling load estimation using 5 years of normalized outdoor temperature, relative humidity, and the building construction data. We applied the hourly-based estimation to a general hospital building with relatively less sudden heat exchange and the results are compared with the measured cooling load of the building. The results show that the cooling loads estimation depends on the indoor cooling design temperature of the building.

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Reduction of Design Variables for Automated Optimization of Injection Mold Cooling Circuit (사출금형 냉각회로 자동최적화를 위한 설계변수 감소 방안)

  • Rhee, B.O.;Choi, J.H.;Tae, J.S.
    • Journal of the Korean Society of Manufacturing Technology Engineers
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    • v.18 no.4
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    • pp.417-422
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    • 2009
  • The injection mold cooling circuit optimization was studied with a response surface method in the previous research. It took so much time to find an optimum solution for a large product due to an extensive amount of calculation time for the CAE analysis. In order to use the optimization technique in the actual design process, the calculation time should be much reduced. In this study, we tried to reduce the number of design variables with the concept of the close relationship between the depth and the distance of cooling channel. The optimum ratio of the distance to the depth of cooling channels for a 2-dimensional problem was 2.0 so that the optimum ratio was again sought out for 4 large automotive parts. Therefore, the number of design variables for the cooling circuit optimization can be reduced in half, resulting in much faster running time for the optimization as a design tool.

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Development of an Air-Water Combined Cooling System (공냉-수냉 혼합냉각계통 개발)

  • Kwon, Tae-Soon;Bae, Sung-Won
    • The KSFM Journal of Fluid Machinery
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    • v.17 no.6
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    • pp.84-88
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    • 2014
  • A long term passive cooling system is considered as the most important safety feature for the nuclear design after the Fukushima Daiichi nuclear power plant accident in 2011. The conventional active pump driven safety systems are not available during a station Black Out (SBO) accident. The current design requirement on cooling time of the Passive Auxiliarly Feedwater System (PAFS) is about 8 hours only. To meet the 72 hours cooling time, the pool capacity of cooling water tank should be increased as much as 3~4 times larger than that of current water cooling tank. In order to extend the cooling time for 72 hours, a new passive air-water combined cooling system is proposed. This paper provides the feasibility of the combined passive air-water cooling system. The current pool capacity of water cooling system is preserved, and the cooling capability is extended by an additional air cooler.

Numerical Analysis of Cooling Channels for Injection Molding Cycle Time Improvement of Plastic Horn Cover for an Automobile (차량용 플라스틱 혼 커버의 사출성형 싸이클 타임 개선을 위한 냉각 채널의 수치해석 연구)

  • Han, Seong-Ryoel
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.17 no.5
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    • pp.84-90
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    • 2018
  • When producing a plastic horn cover for an automobile, since the interval between the ribs on the inner surface is narrow, conventional cooling channels cannot be applied and cooling of the mold is difficult. For this reason, the molding operation cannot be completed within a set cycle time. In this study, a conformal cooling channel was applied on the mold to solve the cooling problem. Injection molding simulation was carried out to confirm the effectiveness of the conformal cooling channel. In the analysis results, the mold temperature at the rib section decreased by 33%, and the mold temperature also decreased by 31%. This reduction in temperature allowed for molding within a set cycle time and demonstrated the effectiveness of the conformal cooling channel.

Cooling Characteristics of Fruits and Vegetables for Pressure Cooling (차압통풍 예냉 청과물의 냉각특성)

  • 윤홍선;박경규
    • Food Science and Preservation
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    • v.4 no.3
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    • pp.237-243
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    • 1997
  • Numerous variables affect product cooling rate of pressure cooling system for fruits and vegetables. These include carton vent area, initial and desired final product temperature, flow rate and temperature of the cooling air, product size, shape and thermal properties and product configuration(whether in bulk or packed in shipping cartons). This study was carried out to determine the influence of each of these variables as they affect cooling time. The opening ratio and number of the vent hole were recomended as 4∼10% and 2∼4ea., respectively, for a minimum alt flow resistance and for a uniform air flow pattern. In the cooling experiment for tomatoes and mandarins, optimum air flow rate was 0.04 m3/min.kg in terms of energy saving. The cooling air temperature should be about 2$^{\circ}C$ less than the desired final product temperature for reducing cooling time.

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Cooling Simulation for Fixed-Bed of Rough Rice (벼 퇴적층 냉각 시뮬레이션)

  • 김동철;김의웅;금동혁
    • Journal of Biosystems Engineering
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    • v.24 no.1
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    • pp.31-40
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    • 1999
  • The objective of this study were to develop a cooling simulation model for fixed-bed of rough rice and to analyze the factors affecting cooling time of rough rice. A computer simulation model based on equilibrium conditions between grain and air was developed to predict temperature and moisture content changes during cooling of rough rice. the result of t-test showed that there were no significant differences between predicted and measured temperature changes on significance model agreed well with measured values. This cooling simulation model was applied to analyze the effect of some factors, such as air flow rate, cooling air temperature and humidity, initial grain temperature and moisture content, and bed depth, on cooling time of rough rice. Cooling rate increased with increase of air flow rate and bed depth whereas it decreased with increase of cooling air temperature and humidity and initial grain temperature. Among these factors, the most important factor was air flow rate. Specific air flow rate of 0.35㎥/min㎥ was required for cooling rough rice in 24 hours.

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Fabrication of Cores for the Injection Mould with a High Cooling Rate and Injection Molding Using the Fabricated Core (고속 냉각 특성을 가진 사출성형 금형 코어 제작 및 사출 성형)

  • Ahn, D.G,
    • Transactions of Materials Processing
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    • v.16 no.7
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    • pp.549-554
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    • 2007
  • The objective of this paper is to investigate into the fabrication technology of cores for the injection mould with three-dimensional conformal cooling channels to reduce the cooling time. The location of the conformal cooling channels has been determined through the injection molding analysis. The mould has been manufactured from a hybrid rapid tooling technology, which is combined a direct metal rapid tooling with a machining process. Several injection molding experiments have been performed to examine the productivity and the validity of the designed mould. From the results of the experiments, it has been shown that the proposed mould can mold a final product within a cooling time of 3 seconds and a cycle time of 21 seconds, respectively.

A Study on the Optimum Cooling Water Temperature Control of an Automotive Engine(I) (자동차용 기관의 냉각수 온도조절 최적화에 관한 연구(I))

  • 박경석;신진식;이경우
    • Journal of the korean Society of Automotive Engineers
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    • v.14 no.2
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    • pp.34-43
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    • 1992
  • The purpose of this study is to consider the performance and exhaust characteristics in the practical engine according to the cooling water temperature change of engine and to set up the optimum cooling condition and to obtain the optimum operating condition of thermostat in the cooling system. In order to accomplish the purpose of this study, authors have used the following procedure. 1. This study is to investigate the influence of the cooling water temperature on the engine performance and the exhaust gas, authors regulated the cooling water temperature by using the special closing circuit and measured the concentration of exhaust gas by using the exhaust gas measuring system in the exhaust pipe. 2. This study carried out the experiment by regulating the opening degree of throttle valve and engine speed in the dynamometer and by changing the cooling water temperature, at the same time kept air-fuel ratio constant and made the spark ignition time MBT(Minimum spark advance for Best Torque) 3. This study measured the cooling water temperature by using the K-type thermocouple centring around the easy over-heated parts and by installing a special closing circuit. Therefore, in this study, authors intend to examine the influence of the cooling water temperature on the engine performance, exhaust gas and present the basic materials needed in the engine design including the optimum operating time control system for the cooling water temperature.

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Cooling Efficiency of Low Pressure Compressed Air Fogging System in Naturally Ventilated Greenhouses (저압 에어포그 시스템을 설치한 온실의 냉방효율)

  • Nam, Sang-Woon;Kim, Young-Shik;Sung, In-Mo;Ko, Gi-Hyuk
    • Journal of The Korean Society of Agricultural Engineers
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    • v.54 no.5
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    • pp.49-55
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    • 2012
  • In order to derive the efficient utilization of low pressure compressed air fogging system, cooling efficiencies with control types were analyzed through cooling experiments in tomato greenhouses. The control types were set up with temperature control, humidity control, temperature and humidity control, and time control. It showed that the cooling effects were 0.7 to $3.3^{\circ}C$ on average and maximum of 4.3 to $7.0^{\circ}C$, the humidification effects were 3.5 to 13.5 % on average and maximum of 14.3 to 24.4 %. Both the cooling and humidification effect were the highest in the time control method. The cooling efficiency of the air fogging system was not high with 8.3 to 27.3 % on average. However, the cooling efficiency of 24.6 to 27.3 % which appears from the time control is similar to the cooling efficiency of high pressure fogging system experimented in Japan. The air fogging system is operated by low pressure, but its efficiency is similar to high pressure. We think because it uses compressed air. From this point of view, we suggest that the air fogging system can get the cooling efficiency of similar levels to that of high pressure fogging system and it will have an advantage from clogging problem of nozzle etc.