• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.10
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• pp.844-853
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• 2002

A dynamic model which simulates the coupled heat and mass transfer within a vertical tube absorber was developed. The liquid film is a binary mixture of two components, and both of these components are present in the vapor phase. The pressure, concentration, temperature and mass flow rate of the vapor are obtained by assuming that the pressure is uniform within an absorber. The model was applied to an absorber for an ammonia/water absorption refrigerator. The transient behaviors of the pressure, the outlet temperature and the concentration of the solution and the cooling water outlet temperature on a step change at the absorber inlet of the cooling water temperature, the vapor mass flow rate and the concentration of the solution were shown.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.9
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• pp.838-844
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• 2004

In a long road tunnel, a tunnel ventilation system may be used in order to reduce the pollution below the required level. To develop control algorithms for a tunnel ventilation system, a dynamic simulation program may be used to predict the pollution level in a tunnel. Research was carried out to develop better pollution models for a tunnel ventilation control system. A neural network structure was adopted and compared by using actual poilution data. Simulation results showed that the dynamic model developed by a neural network may be effective for the development of tunnel ventilation control algorithms.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.21 no.11
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• pp.636-642
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• 2009

Energy consumption data are surveyed and measured to develop energy demand models for hospital buildings as part of a complete package. Daily consumption profiles for electricity, heating, cooling and hot water are surveyed for 14 carefully chosen hospitals to establish energy demand patterns for a time span of a year. Then the hourly demand patterns of the 4 loads are field-measured for different seasons and statistically analyzed to provide higher resolution models. Used in conjunction with energy demand models for other types of buildings, the high resolution of 8760 hour energy demand models for a hospital for a typical year will serve as building blocks for the comprehensive model that allows the estimation of the combined loads for arbitrary mixtures of buildings.

• Proceedings of the SAREK Conference
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• 2008.11a
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• pp.584-589
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• 2008

It is known that slab thermal storage which uses concrete slab as thermal material is effective in the load leveling and using the nighttime electric power. The temperature distribution is not constant in plenum in thermal storage time by beams, ducts such as several factor. It is considered that this fact will effect on efficiency of thermal storage and indoor thermal environment. The purpose of this paper is to examine the thermal environment inside plenum. A macro model was made for the analysis of indoor thermal environment as the first step. The flow rate distribution and temperature distribution of object room model was examined by use of basic equations such as airflow by the pressure difference between unit cells, heat flow by air and heat transfer.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.2
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• pp.157-166
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• 1999

Numerical calculations of turbulent natural convection in an enclosure of the 20 kYA oil-immersed transformer model are presented. The transformer is modelled as two concentric cylinders with different heights and diameters. The thermal boundary layers are well represented in the temperature distributions along the wall of the transformer model. The flow stratification between the hot and cold walls can not be seen in the transformer model. The turbulence eddy viscosity has its maximum at the center of the core and its maximum values at the top of the core are larger than those at the bottom of the core.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.12
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• pp.821-827
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• 2011

A simple analytical model has been developed from the approximate solution of the governing equations for desiccant wheels. The model has been compared with a numerical twodimensional transient model and found capable of making realistic prediction. The analytical model will be further developed to provide simple effectiveness correlations which can be useful for the rough design or long-term simulation of the desiccant wheels in DEC systems.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.37 no.1
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• pp.8-12
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• 2008

기후변화가 한반도 지역기후와 유출량에 미치는 영향을 조사하기 위하여 지역기후모델과 수문모델을 이용하여 고해상도 한반도 70년 장기 지 역기후와 유출량을 생산하였다. 생산된 자료에 따르면 한반도의 미래 지상온도는 현재에 비하여 $1.5^{\circ}C$ 상승하고, 강수량은 0.2 mm $day^{1}$ 만큼 감소한다. 지상온도는 모든 계절에 상승하고, 강수는 초여름을 제외한 모든 계절에 감소한다. 미래의 연평균 강수량이 감소함에도 불구하고, 강수 강도는 증가하고, 집중호우 일수는 증가하였다. 봄과 겨울의 길이가 감소하고, 여름은 증가하며, 봄의 시작이 빨라진다. 금강유역의 유출량은 이수기에는 감소하고, 홍수기에는 증가하는 경향이 나타난다. 이와 같은 한반도의 미래 지역기후 변화로 인하여, 이수기의 물부족, 호우로 인한 재해 피해 증가, 개화시기와 식생군의 변화가 야기될 수 있다.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.18 no.4
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• pp.344-350
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• 2006

The present study investigates the characteristics of fire-driven heat flows and gas concentration in a compartment fire by using the modified VHS model (MVHS). The main idea of this model is to add some source terms for combustion products and oxygen consumption to the original VHS model for providing more accurate and useful information on gas concentration distributions as well as thermal fields. It is found that the present MVHS model shows fairly good agreement with the experimental data and the eddy breakup combustion model. The tilting angle of fire plume calculated by MVHS is larger than that of EBU model because the fire source of VHS is affected by ventilating flow less than EBU. However, this discrepancy is apparently reduced in the downstream region of fire source.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.12 no.1
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• pp.33-39
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• 2000

There are many under going researchs for the natural convection and fluid flow in rectangular enclosure. In this paper, the optimal model that is the most frequently used for the analysis of a turbulent natural convection in rectangular enclosure is suggested by comparing with the result of Cheesewright's experiment. As We can see the distribution of the velocity, temperature, and turbulent kinitic energy, ST model tends to exaggerate the result of the experiment. The LS model generates better experimental result than the ST and DA's. Therefore, it is resonable to adopt the LS model that contains explicit physical meanings of each term in eouation of turbulent kinitic energy.

• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.38 no.12
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• pp.51-60
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• 2009

본 연구에서는 착상 조건 하에서 열교환기 휜의 열전도를 고려하여 휜 표면에서의 착상 거동을 예측하기 위하여 수학적 모델을 제시한다. 이 때, 공기측은 착상 현상에 대한 3차원 유동 변화의 영향을 고려한다. 서리층 두께에 대한 해석 결과는 실험 결과를 최대 10% 오차 내에서 잘 예측한다. 유동에 수직한 방향(z-dir.)의 서리층 두께 성장은 휜의 열전도에 의해 휜 바탕 근처에서 활발하고, 휜 끝으로 갈수록 지수함수적으로 둔화된다. 휜의 열전도를 고려한 경우에 비해 휜의 표면온도가 일정한 조건에서 서리층 두께는 최대 2배, 열전달량은 평군 10% 정도 과대 예측한다. 따라서, 열교환기 휜에서의 착상 거동을 정확하게 예측하기 위해 착상 모델 해석 시 휜의 열전도를 고려해야 한다. 휜의 열전도 고려 유무에 따른 착상 거동의 차이를 보완하기 위해 열전달량에 대한 등가온도를 산출하며, 이를 근거로 무차원 등가 온도 상관식을 도출한다.