• The Magazine of the Society of Air-Conditioning and Refrigerating Engineers of Korea
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• v.4 no.1
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• pp.6-17
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• 1975

For a periodic variation of the flue gas temperature the heat conduction through the Ondol floor was analysized. Also the heat loss to the ground was estimated. The floor thermal capacity, as a function of the floor thickness, has strong influence on the time lag of the temperature variation. It is an important design parameter for intermittent heating. Even for the steady periodic variation, there was significant heat loss to the ground below the Ondol floor.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.11 no.5
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• pp.642-646
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• 1999

Factors governing the rate of heat exchange comprise the air temperature, the speed of air movement, relative humidity, and relation indoors. Recently, there are many researches on the transient analysis of indoor environmental factors such as the dry bulb temperature, relative humidity and air velocity in miniature models. The purpose of this study is to measure the environmental factors and to analyze and evaluate the characteristics of indoor environment with the different envelope structures using a granite dome model. According to the variation of humidity, the state of interior relative humidity for clay model has an equal tendency, although a little range of variation is shown in comparison to the cement model.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.7 no.3
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• pp.538-545
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• 1995

The heat transfer model of ondol heating system is derived in the linear form. The step responses of On-Off controller, PID controller and Position type fuzzy controllers are compared in the sense of several aspects : variation of temperature feedback variable, variation of supplied heat quantity by the boiler, variation of flow rate, variation of thickness of the base, variation of the outdoor temperature.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.3
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• pp.409-424
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• 1987

Simulation on the hot water ONDOL heating system was made in order to investigate the variation of room temperature and specific fuel consumption of boiler. Heat balance equation was derived by response factors and solved implicitly. Variation of room temperature and specific fuel consumption of boiler were calculated with respect to the thickness of room floor, the absorptivity of wall for solar radiation, on-off temperature range of boiler and air exchange. The results show that specific fuel consumption of boiler is independent of the thickness of room floor and decreases with increasing the absorptivity of wall and on-off temperature range of boiler. However, it increases with increasing the air exchange. They also show that, when the absorptivity and on-off temperature range of boiler are increased, the amplitudes of room temperature variation increase.

• Journal of Environmental Impact Assessment
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• v.14 no.3
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• pp.135-145
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• 2005

This study was conducted to investigate the characteristics of meteorological environment variation before and after construction of Nak-dong river estuary barrage. We used meteorological data(air temperature, precipitation, relative humidity, visibility, wind) at Gimhae airport meteorological station. The construction of river estuary barrage can change climate at the neighboring districts and influence human's health and vegetable. The construction of Nakdong river estuary barrage brought rise of temperature, decrease of relative humidity and increase of poor visibility frequency.

• Journal of the Korean Society of Marine Environment & Safety
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• v.29 no.3
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• pp.255-269
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• 2023

Surface water temperature of a bay (from the south to the north) increases in spring and summer, but decreases in autumn and winter. Due to shallow water depth, freshwater outflow, and weak current, the water temperature in the central to northern part of the bay is greatly affected by the land coast and air temperature, with large fluctuations. Water temperature variations are large in the north-east coast of the bay, but small in the south-west coast. The difference between water temperature and air temperature is greater in winter and in the south-central part of the bay than that in the north to the eastern coast of the bay where sea dykes are located. As the bay goes from south to north, the range of water temperature fluctuation and the phase show increases. When fresh water is released from the sea dike, the surrounding water temperature decreases and then rises, or rises and then falls. The first mode of empirical orthogonal function (EOF) represents seasonal variation of water temperature. The second mode represents the variability of water temperature gradient in east-west and north-south directions of the bay. In the first mode, the maximum and the minimum are shown in autumn and summer, respectively, consistent with seasonal distribution of surface water temperature variance. In the second mode, phases of the coast of Seosan~Boryeong and the east coast of Anmyeon Island are opposite to each other, bordering the center of the deep bay. Periodic fluctuation of the first mode time coefficient dominates in the one-day and half-day cycle. Its daily fluctuation pattern is similar to air temperature variation. Sea conditions and topographical characteristics excluding air temperature are factors contributing to the variation of the second mode time coefficient.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.16 no.5
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• pp.438-443
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• 2004

The objective of this paper is to study the effects of the input gas flow rate and the ambient temperature variation on the absorption cycle performance. An air-cooled NH$_3$-$H_2O$ absorption chiller is tested in the present study. The nominal cooling capacity of the single effect maching is 17.6 ㎾ (5.0 USRT). The cooling capacity, coefficient of performance, burner efficiency, and each state point are measured with the variations of the heat input and the ambient temperature. It is found that the COP and cooling capacity increase with increasing the generator exit temperature up to a certain temperature and then decrease. It is also found that the COP and the cooling capacity decrease with increasing the ambient temperature. The maximum COP of 0.51 is obtained from the present experiment.

• Journal of Korean Society for Atmospheric Environment
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• v.14 no.3
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• pp.177-190
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• 1998

The concentrations of air pollutants In large cities such as Pusan area have been increased every year due to the increasing of fuels consumption at factories and by vehicles as well as the gravitation of the population. In addition to the pollution sources, time and spatial variation of air pollutants concentration and meteorological factors have a great influence on the air pollution problem. Especially , its concentration is governed by wind direction, wind speed, precipitation, solar radiation, temperature, humidity and cloud amounts, etc. In this study, we have analyzed various data of meteorological factors using typical patterns of the air pressure to investigate how the concentration of air pollutants is varied with meteorological condition. Using the relationship between meteorological factors (air temperature, relative humidity, wind speed and solar radiation) and the concentration of air pollutants (SO2, O3) , experimental prediction formulas for their concentration were obtained. Therefore, these prediction formulas at each meteorological factor in a pressure pattern may be roughly used to predict the air pollutants concentration and contributed to estimate the variation of its value according to the weather condition in Pusan city.

• Journal of Ecology and Environment
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• v.30 no.2
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• pp.143-149
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• 2007

To certify predictability for the times of phenological stages from cumulative air temperature in springtime, the first times of budding, leafing, flower budding, flowering and deflowering for 14 woody plants were monitored and air temperature was measured from 2005 to 2006 at Namsan. Year day index (YDI) and Nuttonson's Index (Tn) were calculated from daily mean air temperature. Of the 14 woody species, mean coefficient of variation was 0.04 in Robinia pseudo-acacia and 0.09 in Alnus hirsuta. However, mean coefficient of variation was 0.30 in Forsythia koreana and Stephanandra incisa and 0.32 in Zanthoxylum schinifolium. Therefore, the times of each phenological stage could be predicted in the former two species but not in latter three species by two indices. Of the five phenological stages, mean coefficient of variation was the smallest at deflowering time and the largest at budding time. In five phenological stages, mean coefficient of variation of YDI was in the range of $0.11{\sim}0.21$ but that of Tn was in the range of $0.15{\sim}0.26$. Therefore, the former was a better index than the latter. Of the species-phenological stage pair, coefficient of variation of YDI was 0.01 in Acer pseudo-sieboldianum - flower budding and below 0.05 in 11 pairs, whereas the YDIs over 0.40 were 4 pairs comprising of Prunus leveilleana - budding (0.51). Coefficient of variation of Tn was 0.01 in A. hirsuta - budding and below 0.05 in 8 pairs. The Tns over 0.40 were 5 pairs comprising of F. koreana - flower budding (0.66).

• Journal of ILASS-Korea
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• v.3 no.4
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• pp.58-64
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• 1998

In the gasoline engine of fuel injection type, atomization of fuel droplet and its distribution has directly influenced the performance of engine and harmful emission. To investigate atomization characteristics of fuel spray, in this paper fuel spray of air-assisted injector is observed at the various initial conditions of ambient air temperature and air assisted pressure. Behavior of fuel spray is photographed with microscopic visualization system. The SMD of fuel droplet is measured with PMAS (Particle Motion Analysis System). The effect of air-assisted pressure and temperature of ambient air resulted in the decrement of SMD and its variation. Finally, It was found that It was found that from spray angle at the two-hole injector had measured $20{\pm}4$ degree the result of photographs by shadow graphy. The mean diameter of suns decreased and the of droplets increased with increasing the temperature in the spray fields by the results of PMAS measurement. It was found that the characteristics of sprays became finer by increasing the temperature of spray fields about 373K without the delivery of air-assistance.