• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.12
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• pp.836-842
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• 2011

It has been shown that the air-conditioning system with slab cooling storage is effective in cutting peak load and utilizing nighttime electric power. The stochastic properties of internal heat generation which has great influence on the cooling load are examined in this paper. Based on the measured cooling load and electric power consumption in an office building with slab cooling storage, stochastic time series models to simulate these random processes are investigated. Furthermore, a calculated result by an optimal control method of thermal analysis taking into account the internal heat is compared with the measured cooling load.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.61 no.5
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• pp.669-675
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• 2012

Recently, the amount of electrical heat pump(EHP), a electrical conditioning equipment, is sharply increasing due to the luxury and multi-story trend of building. Accordingly, the cooling load that occupying substantial part of summer electric consumption has increased dramatically, making difficulties in domestic supply of electricity in summer. There are some efforts to replace it with an alternative cooling equipment such as gas heat pump(GHP), a gas cooling equipment, in order to solve the problem of summer electricity supply through reducing the summer electricity peak. It is rare, however, to find studies on the actual effects of GHP on the reduction of summer electricity peak. This study, therefore, estimated the effects of the GHP on the summer electricity peak by the gas consumption and characteristics of gas cooling systems. In addition, electric substitution effects by gas cooling systems were analyzed through case studies in the summer of 2010.

• Journal of Power System Engineering
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• v.22 no.6
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• pp.44-50
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• 2018

As a type of bolt with a spherical head, the ball stud is widely used as a part of a ball joint in steering or suspension systems in automobiles. Balls and studs are subjected to heat treatment suitable for each material; in particular, the shear strength of the ball stud must meet the specifications of the production company. This study evaluated the shear strength of joints according to the cooling method of ball studs subject to resistance welding. The shear stress of water cooling was higher than that of air cooling (as-received material). Note, however, th at oil cooling showed lower stress than that of as-received. When judged by standard deviation, mean, and coefficient of variation according to the arithmetic statistics and shape parameter as well as scale parameter, oil cooling is suitable.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2009.06a
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• pp.673-674
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• 2009

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2012.10a
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• pp.270-271
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• 2012

• Journal of Energy Engineering
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• v.27 no.4
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• pp.92-97
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• 2018

This study deals with the numerical analysis for hood development to improve the cooling effect of the engine related components in engine room. Reducing the component temperature in engine room caused by a sudden temperature deviation can minimize the durability degradation of components. Therefore, in this study, numerical analysis for the development of the hood in engine room was carried out in four parts such as generator, battery, ECU and power steel oil which are relatively easy to control temperature among the main components in engine room. In order to verify the numerical analysis, experiments were conducted under the same conditions as those assumed in the numerical analysis.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.1
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• pp.43-49
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• 2015

In recent years, the amount of heat generated inside of the computer has more increased because of high performance, multi-function, miniaturization and light weight. It is necessary to control the effective heat generation to improve performance and life extension of the computer. In this study, thermoelectric cooling system was manufactured using thermoelectric module and was attached to computer in order to control the heat generated inside computer. And the temperature distributions inside computer were experimentally measured and compared with and without thermoelectric cooling system to investigate the effect of cooling system. Also, to estimate the new cooling system which can substitute for the existing computer cooling system, temperature distributions inside computer were calculated by numerical analysis when there was no cooling system and was applied only cooling system to computer.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.8
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• pp.110-115
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• 2009

Recently, there has been a growing global interest in environmental conservation, and the field of electric power equipment has been working to become more environment-friendly. Accordingly, the low noise cooling fan of power transformers was developed through the improvement of blade shape. These are expected to apply to existing power transformers and low noise transformers. It is essential for low noise fan to possess good cooling performance as well as low audible noises. But, there was not analysis on the audible noise level and the cooling performance for low noise cooling fans until present. In this paper, we measure the audible noise level and the flow rate of low noise cooling fans to inspect the performance, Also, we confirmed that the low noise cooling fan is available to apply to power transformers through temperature rise tests of power transformers.

• 한국전산유체공학회:학술대회논문집
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• 2010.05a
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• pp.530-533
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• 2010

This paper presents numerical analysis and design optimization of various turbine blade cooling techniques with three-dimensional Reynolds-averaged Navier-Stokes(RANS) analysis. The fluid flow and heat transfer have been performed using ANSYS-CFX 11.0. A fan-shaped hole for film-cooling has been carried out to improve film-cooling effectiveness with the radial basis neural network method. The injection angle of hole, lateral expansion angle of hole and ratio of length-to-diameter of the hole are chosen as design variables and spatially averaged film-cooling effectiveness is considered as an objective function which is to be maximized. The impingement jet cooling has been performed to investigate heat transfer characteristic with geometry variables. Distance between jet nozzle exit and impingement plate, inclination of nozzle and aspect ratio of nozzle hole are considered as geometry variables. The area averaged Nusselt number is evaluated each geometry variables. A rotating rectangular channel with staggered array pin-fins has been investigated to increase heat transfer performance ad to decrease friction loss using KRG modeling. Two non-dimensional variables, the ratio of the eight diameter of the pin-fins and ratio of the spacing between the pin-fins to diameter of the pin-fins selected as design variables. A rotating rectangular channel with staggered dimples on opposite walls are formulated numerically to enhance heat transfer performance. The ratio of the dimple depth and dimple diameter are selected as geometry variables.

• Journal of Korea Foundry Society
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• v.33 no.1
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• pp.13-21
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• 2013

The effects of rare earth element (R.E.) and cooling rate on the eutectic reaction of flake graphite cast irons were studied by combined analysis of macro/micro-structure and cooling curve data. The correlation between eutectic reaction parameter and macro/micro-structure was systematically investigated. Two sets of chemical compositions with the different addition of R.E. were designed to cast. Three types of molds for cylindrical specimens with the different diameters were prepared to analyze cooling rate effect. The difference between undercooling temperature and cementite eutectic temperature (${\Delta}T_1=T_{U}-T_{E,C}$), which is increased by adding R.E. and decreased by increasing cooling rate, is considered to be a suitable eutectic reaction parameter for predicting graphite morphology. According to the criterion, A-type graphite is mainly suggested to form for ${\Delta}T_1$ over $20^{\circ}C$. Eutectic reaction time (${\Delta}t$), which is decreased by adding R.E. or increasing cooling rate, is a suitable eutectic reaction parameter for predicting eutectic cell size. Eutectic cell size is found to decrease in a proportion to the decrease of ${\Delta}t$.