• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.7
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• pp.578-584
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• 2012

In this study, the analysis on the distribution of indoor airflow velocity and temperature by using numerical simulation has carried out to make fundamental data for establishing the optimum design of laboratory animal facilities. From the results, it was found that replacement of cage lacks, air supply and exhaust system, supply air temperature, supply air velocity affect to the optimum design of laboratory animal facilities as a important element.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.1937-1941
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• 2007

During a process of a nanoimprint for manufacturing LCD, a small temperature variation on the LCD glass can cause thermal stress and generate unexpected displacement. To avoid this trouble, a precision temperature control unit using thermoelectric modules is appropriate for nanoimprint processes. The unit consists of an air control system, a cooling water control system, and a power control system. The air control system includes a thermoelectric module, thermocouples measuring temperatures of air and a duct-stale fin, and two air fans. The heat generated by the thermoelectric module is absorbed by the cooling water control system. The power control system catches the temperature of the thermoelectric module, and a PID controller with SCR controls the input power of the thermoelectric module. Temperature control performance is evaluated by experiment and simulation. The temperature control unit is able to control the exit temperature about ${\pm}2^{\circ}C$ from the incoming fluid temperature, and the error range is ${\pm}0.1^{\circ}C$. However, the control time is approximately 30minute, which needs further study of active control

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.4
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• pp.304-314
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• 2002

Performance analysis of the automotive air-conditioning system is conducted by using computer simulation, and performance tests are carried out by using the climate wind tunnel in order to verify simulation. Evaporator and condenser were modeled by using empirical correlation which was obtained from calorimeter data, and compressor was modeled by using map based method. The steady state thermodynamic conditions of refrigerant satisfying mass and energy balance were assumed in the simulation program for automotive airconditioning system. The system performance was analyzed by finite difference method until differential air enthalpy between evaporator inlet and outlet becomes converged. Simulation results are in good agreement with experimental results at most operating conditions. Variation of discharge temperature and pressure of compressor, outlet temperature of evaporator, cooling capacity, and COP were investigated in term of air volume flow rate for evaporator, compressor capacity, compressor speed, superheat of thermostatic expansion valve, and diameter of suction line.

• 한국태양에너지학회:학술대회논문집
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• 2009.04a
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• pp.155-161
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• 2009

Desiccant systems have been proposed as energy saving alternatives to vapor compression air conditioning for handling the latent load. Use of liquid desiccants offers several design and performance advantages over solid desiccants, especially when solar energy is used for regeneration. The liquid desiccants contact the gas inside the packed column and the heat transfer and mass transfer will occur. This proposal is try study the mass transfer and heat transfer inside the packed column of dehumidifier and regenerator systems. And later on, the rates of dehumidification and regeneration that were affected by desiccant flow rates, air temperature and humidity, and desiccant temperature and all that variation will influence the performance of the systems.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.25 no.11
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• pp.578-584
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• 2013

Vertical open display cases are widely used in shopping malls, supermarkets, or retail stores to sell frozen and refrigerated products. Open display cases use air curtains to maintain a reasonable temperature within the storage space, prevent insects from breaking in, and reduce energy usage. In this research, computational fluid dynamics was used to find the optimal condition for reducing energy by considering various conditions such as discharge speed or temperature of air curtains. Results of the study showed that the amount of energy consumed in the display cabinet is influenced by the discharge speed and temperature of the slots installed on the upper area and the amount of air supplied to the storage area inside the shelf. This shows that the amount of discharged air supplied from the storage area influences the formation of air curtain and also the amount of energy consumption. As a result of this study, we learned that the amount of energy used can be reduced by increasing the amount of discharged air within the storage area and enhancing back pressure.

• Journal of Environmental Science International
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• v.23 no.11
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• pp.1943-1951
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• 2014

In order to clarify the characteristics of Photo-Volatic(PV) power generation over the Korean peninsula with complex terrain, special meteorological observation campaign was carried out for one year from 25 May 2011. Analysis is based on the comparison between observed meteorological elements and PV values generated at rated capacity 200 kW power plants. Solar radiation observed at $15^{\circ}$ inclined surface is 11 % larger than that observed at horizontal surface due to low elevation angel of the sun during winter season. The PV power generation tend to be more similar the variation of inclined surface irradiance than horizontal surface irradiance. Increasing air temperature often induce disturbance of the PV power generation. However, the higher the air temperature in winter season, the higher PV power generation because the PV module may be more activated at higher air temperature. PV generating efficiency tends to be conversed the value of 15%.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.5
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• pp.1115-1128
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• 1994

The condition of temperature gradients in asphaltic concrete (Ascon) pavement have been analyzed based on the data collected from 5 major sites in Korea. From this. considering heat transfer by insolation flux and air temperature within pavement slab. temperature variation on the surface of pavement was computed and numerical model using the theory of thermal conductivity was applied to estimate the temperature gradients in depth. To investigate the present condition of asphalt generally used in Korea. the asphalt property tests were applicated on 5 different AP-3 (AC 85~100), and AP-5 (AC 60~70) asphalts classified by penetration index. Uniaxial compression test and indirect tensile test were also carried out for varying temperature conditions to analyze the effect of temperature on the deformation characteristics of Ascon pavement by calculating the variation of static elastic modulus and layer coefficients.

• Proceedings of the Korea Air Pollution Research Association Conference
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• 2005.11a
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• pp.222-223
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• 2005

• KSTLE International Journal
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• v.1 no.1
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• pp.63-68
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• 2000

Angular contact ball bearings are mainly used in the spindle, which requires high speed and stiffness. The heat generation is studied by experiments and simulations using a pair of angular contact ball bearings. The temperature variation of inner and outer races and the temperature increment distribution are measured by using thermocouples for the rotational speed, preload, viscosity of lubricant. The measured values from experiments are used to estimate the heat conduction rate. The method of oil-air lubrication is used for the experiment. The amount of conduction heat transfer to the test spindle and the convection heat transfer coefficients long the spindle are computed by using inverse method with temperature increment distribution. Total heat generation rate is estimated with the heat partition rate which is calculated from temperatures of inner and outer races. In addition, the empirical factor of oil-air lubrication method for Palmgren's heat generation model is suggested. The empirical friction coefficients, which are obtained from the experiments, depend on the preload condition, and can give us more accurate estimation of the heat generation in ball bearings.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.780-785
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• 2009

The photovoltaic/thermal collectors (PV/T collectors) combine the solar thermal collector and photovoltaic modules. They can produce thermal energy in the form of hot air or hot water, and converts solar radiation into electricity. The collecctors can improve the electrical performance of PV modules as the heat from the PV module carried away by the thermal part of the system keeping temperatures lower. The basic water cooled PVT collector has metallic water pipes attached to the back of a PV collector. There are main parameters affecting the performance (electrical and thermal) of PVT collectors. This paper analyzed the experimental performance of glazed water PVT module, considering the parameters of solar radiation, inlet water temperature and ambient temperature. It found that solar radiation is the dominant factor for the electrical performance of the collector, and for the thermal performance the inlet water temperature and ambient temperature appeared to be more related.