• 한국지열·수열에너지학회논문집
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• 제18권2호
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• pp.10-21
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• 2022

A water source heat pump (WSHP) system is regarded as an energy-efficiency heating and cooling supply system for buildings due to its high energy efficiency and low greenhouse gas emissions. Recently, water sources such as river water, lake water, and raw water are attracting attention as heat sources for a heat pump system in Korea. This paper analyzed the applicability of a river water source heat pump system (RSHP). The river water temperature level was compared with the outdoor air and ground temperature levels to present applicability. In addition, the cooling and heating performance were compared through a simulation approach for the RSHP and a ground source heat pump (GSHP) applied to a large-scale office building. To compare the temperature level, the actual data were applied to the river water and the outdoor air, while the simulation results were applied to the ground circulation water. The results showed that the change in river water temperature throughout the year was similar to the change in outdoor air temperature. However, unlike the outdoor air temperature, the difference between the hourly and daily average river water temperatures was not large. The temperature level of river water was lower during the heating season and somewhat higher during the cooling season than that of the ground circulation water. Finally, the performance of the RSHP system was 13.4% lower than that of the GSHP system on an annual-based.

• 한국식품저장유통학회지
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• 제4권1호
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• pp.33-38
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• 1997

In order to provide informations for designing packaging and storage condition of dry jujube (Zizyphus jujuba MILLER), moisture sorption isotherm was determined for temperatures of 20, 30 and 4$0^{\circ}C$, and quality changes were evaluated as function of temperature and water activity. Dry jujube at a given water activity showed higher equilibrium moisture content for lower temperature. Moisture isothem could be fitted by GAB model equation, giving higher C value, lower m0 and relatively constant k value with increase in temperature. Ascorbic acid was lost more highly at higher temperature and water activity, and showed negligible retention for whole range of water activity and temperature studied after 141 days. Browning increased with water activity up to 0.73 at 30 and 4$0^{\circ}C$. Dry jujube of high water activity had high L value in surface color, which represent brightness of surface color. Considering quality retention in the storage, dry jujube is desired to be dried to water activity of 0.42 and be stored at temperature below 3$0^{\circ}C$

• 환경영향평가
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• 제21권5호
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• pp.715-724
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• 2012

In this study, we simulated water temperature in the downstream according to withdrawal types of dam using EFDC model. Three scenarios were assumed as water was released from the surface layer, the middle layer, and the bottom layer at intervals of 10m depth. In case of the surface layer withdrawal, the water temperature rose from March and lowered gradually after it reached a peak in August. The middle and the bottom layers effluence temperatures were lower than the surface layer temperature by maximum $15.9^{\circ}C$(in July), but after September, temperature inversion appeared. It was advantageous for the surface layer withdrawal to decrease cold damage and fog in downstream area and was possible to the middle and the bottom layers withdrawal from August to September. However, the reliability of model should be improved by accumulating the real-time information of water temperature.

• 태양에너지
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• 제8권2호
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• pp.46-56
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• 1988

This investigation concerns thermal stratification of the water due to the temperature difference (${\Delta}T=T_{\infty}-T_i$) between the mean temperature of the water in the test tank (1m wide, 1m high, 2.1m long) and the temperature of the inflow water into the tank; flow rate of circulating water and height of the sink diffuser in the test tank. The additional objectives was to observe a stratification phenomena near an interface by measuring the velosities and the temperature difference and investigate an availabilities of the better effective hot water through establishing thermocline near an interface around the bottom of the tank. Following results were obtained through the experiments. 1. When the flow rate was constant and the temperature difference (${\Delta}T=T_{\infty}-T_i$) between the mean temperature of the flow in the test tank and the temperature of the inflow water increased by 5.6, 9.5, 13.5($^{\circ}C$), obtained the better effective advantage of hot water and the stress near an interface increased gradually. 2. When the ${\Delta}T=T_{\infty}-T_i$ was constant and flow rate increased by 4.0, 4.8, 6.4, 8.0 (LPM), obtained the better effective advent age of hot water and the mean stress near an interface increased gradually. 3. When the height of the sink diffuser was 25cm from tank bottom in comparison with 50cm, obtained the better effective advantage of hot water and the mean stress near an interface increased.

• 한국환경과학회지
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• 제26권10호
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• pp.1125-1133
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• 2017

In this study a method for filling in missing data of river water temperature using a pre-constructed mathematical relationship between air and water temperatures is presented. A regression between water temperatures at individual stations and ambient air temperatures at nearby weather stations can provide a practical method for representing missing water temperature data for an entire region. Air and water temperature data that were collected from two test sites (one coastal and, one inland) were individually fitted to a nonlinear regression model. To consider seasonal hysteresis effects, separate functions were fitted to the data in the rising and falling limbs. A single-criterion, multi-parameter optimization technique was used to determine the optimal parameter sets. This method minimizes the differences between the time series of the measured and estimated data. The constructed air-water temperature relationship was subsequently applied to represent missing water temperature data. It was found that the RMSEs(MBEs) were in the range of $1.843-1.976^{\circ}C(-0.329-0.201^{\circ}C)$ and the coefficient of determination were in the range of 0.92-0.96. The results demonstrate that the predicted water temperatures using the regression equations were reasonably accurate.

• Preventive Nutrition and Food Science
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• 제12권2호
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• pp.111-114
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• 2007

Water vapor adsorption kinetics of Inonotus mushroom powders were investigated in temperature and water activity ranges of 20 to 40$^{\circ}C$ and 0.30 to 0.81, respectively. Initial water vapor adsorption rate of mushroom powders increased with increases in temperature and water activity. The temperature dependency of water activity followed the Clausius-Clapeyron equation. The net isosteric heat of sorption increased with an increase in water activity. Water vapor adsorption kinetics of the mushroom powders can be well described by a simple empirical model. Temperature dependency of the reaction rate constant followed the Arrhenius relationship. The activation energy ranged from 56.86 to 91.35 kJ/mol depending on water activity. Kinetic compensation relationship was observed between k$_o$ and E$_a$ with the isokinetic temperature of 790.27 K.

• 자원환경지질
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• 제32권2호
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• pp.169-175
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• 1999

The water leakage of reservoir embankment usually occurs through water vein, which gives little influence on the embankment in a normal state. However, the embankment can be destroyed when the water level of reservoir increases with heavy rain in summer. Investigating the water vein and its path is therefore very important from the viewpoint of disater prevention and embankment protection. This paper presents survey results of one-meter-depth ground temperature and multi-point temperature logging in an embankment in Japan to delineate water veins and permeable formations. Four water veins have been predicted in the embankment by comparing measured one-meter-depth ground temperatures with the background ones which have no effect of water vein. The multi-point temperature logging was carried out in the borehole drilled at one of the predicted water veins. Depth and thickness of the permeable formation in the borehole can be determined from temperature restoration ratios with elapsed time. From these results we can find that the water leakage of reservoir embankment mainly occurs in sandy soil formation in the embankment.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2010년도 춘계학술대회 초록집
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• pp.170.2-170.2
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• 2010

The amount of the heating and cooling energy of water source heat pump using the raw water from the Paldang water intake station is investigated in the study. The Han river water is conveyed in the large-size shallowly buried pipe. Averaged water temperature at the position, 27 km from the Paldang water intake station, is increased by $1.11^{\circ}C$ due to the geothermal energy transfer under the ground, therefore the raw water has more thermal energy than the river water. To estimate of the thermal energy for the raw water, it is assumed that the water source heat pump is used for the heating and cooling ventilation. When $5.0^{\circ}C$ temperature difference energy of the raw water is used in the heat pump system all the year except for the January and February in which $3.0^{\circ}C$ temperature difference energy is used. It is predicted that total 5,766.3 Tcal could be used in the metropolitan area a year, which is about 3.0% of the river water unutilized energy resources.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2011년도 춘계학술대회 초록집
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• pp.202-202
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• 2011

Performance of the raw water-source heat pump system with a thermal storage tank has been analyzed in winter season. The raw water is transferred through the multi-regional water supply system from Han river. Raw water is large temperature difference resource compared with groundwater. Although the raw water temperature drops to $0.6^{\circ}C$ due to the heavy snowfall and the severe cold in late January and early February, 2010, the system has been normally operated without any trouble this winter. The unit COP and system COP considered all pump power consumption were estimated based on the second-by-second data of the all sensors. The monthly averaged unit COP and system COP are 3.37 and 2.76 respectively with $1.4^{\circ}C$ of raw water in January, 3.55 and 2.89 with $1.6^{\circ}C$ raw water in February, 3.82 and 3.15 with $5.4^{\circ}C$ raw water in March. The performance of the system are increased with raw water temperature, and the COPs are higher than the water-to-air heat pump system using relatively high temperature raw water from Daecheong reservoir because the water-to-water system was operated on the full load condition and was stopped when the thermal storage tank was full of the high temperature water.

• 대한치과보철학회지
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• 제14권1호
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• pp.47-54
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• 1976

Pulpal temperature is changed in response for various conditions which were mechanical, thermal, chemical and biological stimuli. This study was performed to determine the pulpal temperature changes which were using air turbine with air-water coolant, water coolant, and conventional dental engine with water coolant and no coolant on 28 canine of dogs. In order to record pulpal temperature, pulp chamber was opened on the labiocervical area of canine. Thermocouple was inserted into pulp chamber and was fixed with filling material(dycal). Changes of pulpal temperature were recorded on the physiograph, which had been standardized temperature degree, through thermocouple to thermistor bridge and carrier preamplifier. The amount of experimental temperature change to that of control was interpreted in the pulpal cavity. The obtained results were as followings: 1. The mean normal temperature was 33.07 centigrade. 2. The temperature was decreased than normal pulpal temperature. It was 12.04 centigrade in reduction by air turbine with air-water coolant, 7.17 centigrade in reduction by air turbine with air coolant, 5.54 centigrade in reduction by conventional engine with water coolant, and 1.26 centigrade in reduction by conventional engine with no coolant. 3. The time for maximal temperature change was 53.3 seconds in reduction by air turbine with air-water coolant, 73.4 seconds in reduction by air turbine with air coolant, 50.9 seconds in reduction by conventional engine with water coolant, and 27.1 seconds in reduction by conventional engine with no coolant. 4.. After reduction was ceased, the recovery time to normal pulp temperature was 287.1 seconds in air turbine with air-water coolant, 189.0 seconds in air turbine with air coolant, 86.9 seconds in conventional engine with water coolant, and 52.9 seconds in conventional engine with no coolant respectively.