• 한국물환경학회지
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• 제26권5호
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• pp.822-833
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• 2010

Temperature increase due to climate changes causes change of water temperature in rivers which results in change of water quality etc. and the change of river ecosystem has a great impact on human life. Analyzing the impact of current climate changes on air and water temperature is an important thing in adapting to the climate changes. This study examined the effect of climate changes through analyzing air temperature trend for Nakdong river basin and analyzed the elasticity of air-water temperature to understand the effect of climate changes on water temperature. For analysis air temperature trend, collecting air temperature data from the National Weather Service on main points in Nakdong river basin, and resampling them at the units of year, season and month, used as data for air temperature trend analysis. Analyzing for elasticity of air-water temperature, the data were collected by the Water Environment Information system for water temperature, while air temperature data were collected at the National Weather Service point nearest in the water temperature point. And using the results of trend analysis and elasticity analysis, the effect of climate changes on water temperature was examined estimating future water temperature in 20 years and 50 years after. It is judged that analysis on mutual impact between factors such as heat budget, precipitation and evapotranspiration on river water temperature affected by climate changes and river water temperature is necessary.

• 한국물환경학회지
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• 제35권4호
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• pp.308-315
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• 2019

The objective of this study was to investigate mountain stream water and air temperatures, area, latitude, altitude, and forest coverage in headwater catchments located in Kangwon-do, Mid-eastern Korea from 2015 to 2017. Daily mean value of mountain stream water temperature was approximately $6^{\circ}C$ lower than the daily mean value of air temperature on the monitoring sites during the observation period. Monthly mean value of mountain stream water temperature increased with increasing monthly mean value of air temperature from May to August during the observation period. Seasonal variations of mountain stream water temperature were dependent on air temperature rising and falling periods. Correlation analysis was conducted on mountain stream water temperature to investigate its relationship with air temperature, area, latitude, altitude, and forest coverage of air temperature rising and falling periods. The correlation analysis showed that there exists a relationship (Correlation coefficient: -0.581 ~ 0.825; p<0.05), particularly the air temperature showed highest correlation with mountain stream water temperature. Regression equations could be developed due to contribution of air temperature to affect mountain stream water temperature (Correlation coefficient: 0.742 and 0.825; p<0.01). Therefore, a method using various parameters based on air temperature rising and falling periods, could be recommended for predicting mountain stream water temperature.

• 한국생활과학회지
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• 제19권4호
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• pp.745-760
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• 2010

The purposes of this study were to investigate the state of indoor thermal and air environment during winter in the one-room type multi-family houses occupied by university students and to analyze factors which influenced this environment. Field survey was conducted in 10 houses between 30th January, 2009 and 13th February, 2009 which measured indoor thermal and air elements as well kept records of interviews with residents and other related factors. Measured elements were air temperature, relative humidity, as well as concentrations of $CO_2$, CO, TVOC, and PM-10. The results can be summarized as follows. 1) The mean air temperature in each house ranged from 19.3 to $25.3^{\circ}C$, so most houses were not suitable for evaluation criteria($20-22^{\circ}C$). The average $CO_2$ concentration in each house was 965~3259ppm, so most houses exceeded evaluation criteria(1000ppm). The average TVOC concentration in each house were 0.00~1.17ppm, 5 houses exceeded evaluation criteria(0.12ppm). 2) Relative humidity, CO concentration, and PM-10 concentration were suitable for evaluation criteria. Therefore, indoor thermal and air environment during winter in one-room type multi-family housing occupied by university students was found to be generally uncomfortable. Important factor which were found to influence air temperature and the concentration of $CO_2$ were smaller space capacity than general house. Other factors which were found to influence the environment of these houses were the existence of a balcony as well as factors relating to the behavior of occupants such whether or not heating were operated, whether windows were opened, whether fans used, whether occupants smoked or used cosmetics, and whether the space was dusted.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2007년도 동계학술발표대회 논문집
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• pp.322-327
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• 2007

Dedicated outdoor air-conditioning(DOA) system that utilizes pre-cooling and desiccant dehumidification can be superior to conventional cooling and reheating system with respect to energy consumption and indoor thermal comfort. In this work, simulation has been conducted to study various factors that affect the performance of DOA. Dynamic simulation shows the transient variation of temperature and humidity as the on/off control logic is imposed. Exit humidity of process air and flow rate are varied to study the effect on exit temperature of process air, dehumidification quantity, required regeneration temperature and exit humidity of regeneration air. For an outdoor air condition of $28.5^{\circ}C$ temperature, 16 g/kg humidity ratio and 2000 cmh flow rate, the dehumidification efficiency is increased by 4.6% as the flow rate is doubled.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2006년도 추계학술대회
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• pp.372-375
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• 2006

SOFC is a high temperature fuelcell with many advantages, but it also have several demerits. One of the Issues is cathode poisoning of Cr coming from stainless steel interconnects. Diffusion process of Cr evaporated from the surface of interconnect steel was calculated by using CFD technique to understand factors for Cr deposition. It has been cleared that factors concerned in Cr deposition and how they affect Cr deposition. Major variables for Cr deposit ion are diffusion coefficient, air velocity and temperature If diffusion coefficient decreases, Cr concentration increases in the air but decreases on the cathode surface. Increasing in air velocity, Cr concentration decreases in the air and on the cathode surface. Increase in temperature leads to rising Cr concentration on the cathode surface because of diffusion coefficient increment.

• Steel and Composite Structures
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• 제46권5호
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• pp.669-672
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• 2023

In this research, the researcher has examined the factors affecting the movement of the soccer ball and will show that the effects such as air resistance, altitude above sea level, wind, air pressure, air temperature, air humidity, rotation of the earth, changes in the earth's gravitational acceleration in different areas. It, the geographical length and latitude of the launch point, the change of gravitational acceleration with height, the change of pressure with height, the change of temperature with height and also the initial spin (Magnus effect) affect the movement of projectiles (especially soccer ball). We modelled th ball based on shell element and derive the motion equations by energy method. Finally, using numerical solution, the wave of the ball is studied. The influences of various parameters are investigated on wave propagation of the ball. Therefore, in short, it can be said that the main factors that play a major role in the lateral deviation of the hit ball are the initial spin of the ball and the wind.

• 설비공학논문집
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• 제17권5호
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• pp.397-403
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• 2005

The thermal comfort of occupants is directly related to several environmental factors such as velocity of air flow, turbulence intensity and temperature distribution of indoor air. The purpose of this study is to evaluate the indoor air flow and temperature distribution in office area using under-floor air-conditioning system (UFAC System) based on the results from physical measurements and to perform a Computer Fluid Dynamics (CFD) under the same condition of inlet and outlet as field measurement. The results from the CFD simulation are similar to those from the field measurement. The results show that UFAC system is provide proper indoor condition for occupants.

• 한국작물학회지
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• 제19권
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• pp.100-131
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• 1975

To obtain basic information on the improvement of naked barley production. and to clarify the relation-ships between yield or yield components and some meteorogical factors for yield prediction were the objectives of this study. The basic data used in this study were obtained from the experiments carried out for 16 years from 1958 to 1974 at the Chon-nam Provincial Office of Rural development. The simple correlation coefficients and multiple regression coefficients among the yield or yield components and meteorogical factors were calculated for the study. Days to emergence ranged from 8 to 26 days were reduced under conditions of mean minimum air temperature were high. The early emergence contributed to increasing plant height and number of tillers as well as to earlier maximum tillering and heading date. The plant height before wintering showed positive correlations with the hours of sunshine. On the other hand, plant height measured on march 1st and March 20th showed positive correlation with the amount of precipitation and negative correlation with the hours of sunshine during the wintering or regrowth stage. Kernel weights were affected by the hours of sunshine and rainfall after heading, and kernel weights were less variable when the hours of sunshine were relatively long and rainfalls in May were around 80 to 10mm. It seemed that grain yields were mostly affected by the climatic condition in March. showing the negative correlation between yield and mean air temperature, minimum air temperature during the period. In the other hand, the yield was shown to have positive correlation with hours of sunshine. Some yield prediction equations were obtained from the data of mean air temperature, mean minimum temperature and accumulated air temperature in March. Yield prediction was also possible by using multiple regression equations, which were derived from yield data and the number of spikes and plant height as observed at May 20th.

• 생물환경조절학회지
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• 제16권4호
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• pp.291-296
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• 2007

이 연구는 순환팬에 의해 만들어지는 수평적인 공기흐름이 환경요인들의 수평 및 수직분포에 미치는 영향을 조사하기 위해 수행하였다. 순환팬 가동 유무에 따라 기류 속도, 기온, 상대습도 및 $CO_2$농도의 3차원 분포를 측정하였다. 온실내 기상인자 분포의 균일성은 외기온이 낮아짐에 따라 감소하였다. 무처리시 기온 편차는 4.7, 습도 편차는 19%이었는데 팬을 가동한 경우 그 편차들은 각각 2.2, 6.3%로 감소하였다. 팬 용량이 증가할수록 측점간 기온 편차가 줄어들었는데, 온실 바닥면적당 $0.0104m^3{\cdot}s^{-1}$ 용량의 팬으로 온실내 적정한 공기 유동을 만들 수 있었다. 기온 및 $CO_2$ 농도의 수직분포는 높이나 팬 용량에 관계없이 상당히 균일한 것으로 나타났다. 폭 방향의 기온 편차를 줄일 수 있는 팬 배치와 소용량의 팬을 다수 설치했을 때의 효과에 대한 연구가 더 필요할 것으로 생각된다.

• 설비공학논문집
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• 제22권11호
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• pp.773-780
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• 2010

The dispersion of plume which is emitted from a chimney is governed by a lot of factors： wind, local terrain, turbulence intensity of atmosphere, and temperature, etc. In this study, we numerically investigate the plume dispersions for various altitudinal temperature gradients and wind speeds. The normal atmosphere has the temperature decrease of $0.6^{\circ}C/100m$, however, actually the real atmosphere has the various altitudinal temperature profiles according to the meteorological factors. A previous study focused on this atmospheric temperature gradient which induces a large scale vertical flow motion in the atmosphere thus makes a peculiar plume dispersion characteristics. In this paper, the effects of the atmospheric temperature gradient as well as the wind speed are investigated concurrently. The results for the developing processes in the atmosphere and the affluent's concentrations at the ambient and ground level are compared under the various altitudinal temperature gradients and wind speeds.