• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.14 no.3
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• pp.240-246
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• 2002

Bypass air conditioning systems are divided into three types; an outdoor air bypass, a mixed air bypass and a return air bypass system. What makes the return air by pass system more effective is that it directs all of moist outdoor air through the cooling coil. The bypass air conditioning system can maintain indoor R.H (Relative Humidity) less than a conventional CAV (Constant Air Volume) air conditioning system by adjusting face and bypass dampers at part load. When a design sensible load (the ratio of sensible load to total sensible load) is 70 percent (at this time, RSHF (Room Sensible Heat Factor) . 0.7), indoor R.H was maintained 59 percent by the return air bypass system, but 65 percent by the conventional CAV air conditioning system (valve control system). The bypass air conditioning system can also improve IAQ (Indoor Air Quality) in many buildings where the number of air change is high.

• Journal of Environmental Science International
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• v.29 no.10
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• pp.981-988
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• 2020

This study presents meteorological data integrity to improve environmental quality assessment in Yongdam catchment. The study examines both extreme ranges of meteorological data measurements and data reliability which include maximum and minimum temperature, relative humidity, dew point temperature, radiation, heat flux. There were some outliers and missing data from the measurements. In addition, the latent heat flux and sensible heat flux data were not reasonable and evapotranspiration data did not match at some points. The accuracy and consistency of data stored in a database for the study were secured from the data integrity. Users need to take caution when using meteorological data from the Yongdam catchment in the preparation of water resources planning, environmental impact assessment, and natural hazards analysis.

• Proceedings of the SAREK Conference
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• 2009.06a
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• pp.224-229
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• 2009

Performance curve of the desiccant rotor is an important information when developing and selecting the desiccant dehumidifier. The effective utilization of the energy is major capacity for the system and the desiccant performance curve is a design ability for a designer. By the rotor supply contract with DRI, ECO-DRY programs would be offered. Moreover, it could make remarkable progress in the desiccant system and energy saving. It is good to introduce the programs with the amicable help of DRI.

• Proceedings of the KIEE Conference
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• 1997.11a
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• pp.567-569
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• 1997

A control system using a PLC has been developed for a single tower drier(STD) in a CANDU type nuclear power plant. This system will replace the existing STD control system which was implemented with mechanical timers and relays. The new control system makes it possible for an operator to perform more precise time and dew point control for the STD, thanks to the high efficiency and flexibility of the PLC. The operational cost for the control system is much reduced compared to the existing system.

• Journal of Environmental Impact Assessment
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• v.20 no.5
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• pp.601-613
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• 2011

This study is focused on a climate data integrity to improve water quality assessment due to the social development projects. The study is in an attempt to calculate both extreme ranges of weather data measurements and partly provide means to assess qualification of data which fall within the extremes at the 23 meteorological weather stations. Generally speaking, maximum temperature, minimum temperature, relative humidity, dew point temperature are in the range of reasonable accuracy. However, there found some outliers of the brightness sunshine hours in Cheonan station. Also some years in Gwangju, Seoul, Wonju, Busan, and Jeju never reach to their upper limit and perhaps the calibration of the equipment is doubtful. The users need to take cautions in using the brightness sunshine hour data in preparation of water resources planning and management by estimating evapotranspiration and river discharge, and/or growth rate of the algae (phytoplankton).

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.24 no.11
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• pp.759-766
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• 2012

To estimate the cooling load for the following day, outdoor temperature and humidity are needed in hourly base. But the meteorological administration forecasts only maximum and minimum temperature. New methodology is proposed for predicting hourly outdoor temperature and humidity by using the forecasted maximum and minimum temperature. The correlations for normalized outdoor temperature and specific humidity has been derived from the weather data for five years at Seoul, Daejeon and Pusan. The correlations for normalized temperature are independent of date, while the correlations for specific humidity are linearly dependent on date. The predicted results show fairly good agreement with the measured data. The prediction program is also developed for hourly outdoor dry bulb temperature, specific humidity, dew point, relative humidity, enthalpy and specific volume.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1201-1206
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• 2008

Psychrometric chart displays graphically the thermophysical properties of moist air, so it is very conveniently used in air-conditioning and refrigeration. On general psychrometric chart, there are dry bulb temperature, web bulb temperature, absolute humidity ratio, relative humidity, specific enthalpy, specific volume, sensible heat factor, and enthalpy-humidity difference ratio. However, various state and process values besides aboves can be plotted on psychrometric chart. In this study, we developed the software drawing twenty kinds of lines, that is vapor pressure, mole fraction ratio of vapor, dew point temperature, degree of saturation, density, specific entropy, specific exergy, contact or bypass factor, uncomfort index, discomposition index, predicted mean vote index, predicted percent dissatisfied, and so on. We wish to this software is a help to design, analysis and education.

• Proceedings of the KIEE Conference
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• 1998.07g
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• pp.2321-2323
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• 1998

A control system using a PLC has been developed for a dual tower drier(DTD) in a CANDU type nuclear power plant. This system will replace the existing DTD control system which was implemented with mechanical timers and relays. The new control system makes it possible for an operator to perform more precise time and dew point control for the DTD, thanks to the high efficiency and flexibility of the PLC. The operational cost for the control system is much reduced compared to the existing system.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2007.11a
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• pp.101-104
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• 2007

Currently most of underground structures in domestic apartment projects are being designed for parking lot and essential parking area is growing due to the increase in car-holding number per household. Moreover, most underground parking lots of today are combined with basement, therefore a pleasant environment in underground space is strongly needed for the dwellers' use. However, there always occur high percentage of humidity and surface condensation in underground parking lot because of the nature of underground structure and they are having a bad influence on the comfort and health of dwellers. Therfore, this study is planned to compare and examine the porformance and properties of currently used construction methods to prevent condensation and finally present the most suitable method.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.13 no.11
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• pp.1125-1133
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• 2001

Since the surface temperature of the evaporating tube in an ammonia unit cooled is lower than the dew point of atmosphere, the moisture in the atmosphere condenses and the frost grows on the tube. The frost of liquid film decreases the heat transfer rate. The reliable analysis of the heat transfer is required for the prediction of the optimal design of the ammonia unit cooler. For the specific commercial model, the performance was numerical1y estimated for the variation of operating condition and geometric configuration. It is found that there exists an optimum range for the parameters such as mass flow rate of air and refrigerant, humidity, refrigerant quality, fin pitch, the number of step, the number of rows and the pattern of refrigerant path.