• Applied Chemistry for Engineering
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• v.21 no.2
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• pp.169-173
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• 2010

Many salts have the ability to attract and remove water vapor from the surrounding environment. The ability of each salt to remove water vapor is based on the flow rate and temperature of air in surrounding. The objective of this study was toinvestigate the humid control characteristics in air-water system by using a desiccants. The aim is to asses the influence of three parameters on the humid control process which are air volume rate, air temperature and desiccant amount. Humidity control materials which consist of K (potassium) or Na (sodium) have been synthesized by the aqueous process. The humidity control properties of materials have been also investigated. Experiment results are as following. Thermal characteristics of desiccants showed similar properties regardless of processing condition. The experiments were examined by using artificial air-water system (humidity : 70~93%, air volume rate : $0.22{\sim}0.69m^3/s$). The results showed that the Na-type desiccant was an effective material. It was found that dew point increased with air volume rate, and the humidity change in humid control process was depended on desiccants amount.

• Journal of Energy Engineering
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• v.17 no.1
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• pp.1-7
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• 2008

The present study has been conducted to understand the heat and mass transfer characteristics of humid airflow in frosting conditions. A flat plate of aluminum was used for the simulation of flat surface part of the fin of the heat exchanger. The aluminum surface temperatures were measured and analyzed to clarify the heat and mass transfer characteristics under frosting conditions. Also, the pressure drops were measured to clarify the air-blocking effect of frost in the mini channel of the air-side hoot exchangers. A data reduction method was developed far the analysis of local characteristics of humid air under frosting conditions.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.23 no.11
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• pp.747-753
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• 2011

The purpose of this study was to quantify the impact of the ventilation rate on heating and cooling energy consumption in a detached house. For it, a series of simulations for the application of the diverse ventilation rate (ACH) were computationally conducted for a prototypical detached residential building in the cold climate (Detroit, Michigan) and hot/humid climate (Miami, Florida) of USA. Analysis revealed that ventilation is a significant heat losing source in the cold climate; thus, the higher ventilation rate significantly increases the heating energy consumption and energy cost in the cold climate; while the impact on energy increase for heating and cooling energy consumption is similar in hot/humid climate with less significancy compared to cold climate. The research outcome of this study could be a fundamental data for determining the optimal ventilation rate in terms of indoor air quality, but also building energy performance well.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.145-146
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• 2002

Tribological properties of co-sputtered Molybdenum disulfide $(MoS_2)/Carbon\;(C)$ films were studied and compared with those of sputtered $MoS_2$ films. Friction tests were carried out using pin-on-disk friction testers to evluated their friction and wear behaviors in a vacuum ($10^{-5}Pa$), air and humid air of 30, 50, 80% RH. $MoS_2/C$ (14%) composite films exhibited about 9 times longer wear life in a vacuum and about 6 times longer wear life in dry air than $MoS_2$ films did. They also showed stable low friction coefficient of about 0.02 in a vacuum. In humid air, however, $MoS_2/C$ composite films hardly showed good tribological properties.

• Journal of the Ergonomics Society of Korea
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• v.17 no.3
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• pp.41-59
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• 1998

Thermal comfort aspect of a locally-cooled target space in warm and humid environments(typically in the rainy summer season) was studied in view of PPD index. First. theoretical analyses were conducted to examine the effect of the governing parameters(such as air temperature, relative humidity and air velocity, etc.) using a computer model. Secondly, experimental investigations were also performed in a climatic room designed to simulate corresponding thermal conditions of outdoor environments. During the tests, temporal variation of PPD was recorded as functions of climatic variables(outdoor and indoor temperatures, relative humidity and air velocity) for the given human factors(metabolic heat generation and clothing). From both theoretical and experimental investigations, air temperature and air velocity were found to be the most dominant parameters affecting PPD of the target space. Results were summarized as: 1. Relative humidity of the locally-cooled target space tends to approach that of outdoor's as the space is subjected to an ON-OFF mode of cooling, since moisture potential of the two rooms reaches an equalized state as a result of moisture diffusion. 2. It was recognized that changes in relative humidity did not show any significance in view of thermal comfort as was reported in the previous studies, while variations of both temperature and air velocity caused relatively large changes in the degree of thermal comfort. 3. In-door environment should be evaluated in terms of PPD instead of relative humidity commonly recognized as an important climatic variable particularly in warm and humid environments.

• Journal of Fisheries and Marine Sciences Education
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• v.28 no.4
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• pp.1107-1113
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• 2016

In the environment with high humidity causes negative influence on human's body and living condition. As the weather gets more humid, people's interest of dehumidifier for household arising recently. The cooling dehumidifier dehumidify the air by using refrigeration cycle technology which means it removes vapor by let the humid air pass through the cold surface. The amount dehumidified of refrigerating method dehumidifier affected by multiple factors. However, the refrigerating method dehumidifier for household in the market controls pass wind velocity technology to adjust the amount of dehumidification. As the pass wind velocity increases, the amount of wind increases hence the heat exchange amount increases accordingly. However, the amount of dehumidification decreases because the temperature difference between the air and vaporization decreases. Therefore, simply by increasing air velocity does not increase the amount of dehumidification. This research examined the effect of air velocity out of all variety of factors to the amount of dehumidification for refrigerating method dehumidifier.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.27 no.12
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• pp.620-625
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• 2015

The summer climate is very hot and humid in Korea. Humidity is an important factor in determining thermal comfort. Recently, research on dehumidification device development has been attempted to save the energy required for operating the dehumidifier. Existing dehumidification systems have disadvantages such as wasting energy to drive the compressor. Meanwhile, dehumidification systems with membranes can dehumidify humid air without increasing the dry bulb temperature. Therefore. they don't have to consume cooling energy. In this paper, the installation conditions for a membrane system were analyzed to improve the shape and optimum performance of the system. The results showed that the distance between elements was the critical system design factor, and that a distance of 20 mm was the optimal condition for the pressure drop and flow characteristics of the internal air flow.

• International Journal of Air-Conditioning and Refrigeration
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• v.17 no.4
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• pp.129-134
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• 2009

The objectives of this paper are to study the effects of thermal and geometric conditions on the performance of indoor heat exchangers with R-410A for Gas Engine Driven Heat Pump (GHP) application and to find the optimum design conditions of indoor heat exchangers by parametric analysis for the key parameters. The key parameters are number of tube row, number of tube pipe, fin pitch and transverse tube pitch. In the air side, moisture out of the humid air condenses on the fin surface while the refrigerant (R-410A) boils inside the smooth tube. Therefore this study uses Log Mean Enthalpy Difference (LMHD) method to analyze the heat transfer from the humid air to the refrigerant. This study determines the heat exchanger size, air side/refrigerant side pressure drop and overall heat transfer coefficient. Optimum design conditions for the key parameters are also determined by the parametric analysis. The results show that number of rows and pipes, fin pitch have significant effect on the heat exchanger size. It is also found that the tube length of the louver fin is $17{\sim}30%$ shorter than that of the plate fin.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.1
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• pp.15-20
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• 2017

The summer climate is very hot and humid in Korea. The humidity is an important factor in determining thermal comfort. Recently, the research for dehumidification device development has been attempted to save energy that is required for the operation of the current dehumidifiers on the market. Existing dehumidification systems have disadvantages such as wasting energy to drive a compressor. Meanwhile, dehumidification systems with membranes can dehumidify humid air without increasing the dry bulb temperature so it doesn't have to consume cooling energy. In this paper, the cooling energy savings was studied when a dehumidification system was applied in a model building instead of a chiller. The sensible heat load was almost the same result, but the latent heat load was decreased by 38.9% and the total heat load was decreased by 8.5%. As a result, electric energy used to drive the compressor in a chiller was saved by applying a membrane air-conditioning system instead.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.317-322
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• 2008

The objectives of this paper are to study the effects of thermal and geometric conditions on the performance of indoor heat exchanger with R410A for Gas Engine Driven Heat Pump (GHP) application and to find optimum design conditions of indoor heat exchanger by parametric analysis for the key parameters. In the air side, moisture out of the humid air condenses on the fin surface while the refrigerant (R410A) boils inside the smooth tube. Therefore this study uses Log Mean Enthalpy Difference (LMHD) method to analyze the heat transfer from the humid air to the refrigerant of R410A. The results show that fin pitch and longitudinal pitch have significant effect on the heat exchanger preformance. This study will provide the guideline for optimum design of indoor heat exchanger with R410A for GHP application.