• 한국대기환경학회지
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• 제2권3호
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• pp.1-10
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• 1986

Nowadays, air pollution by increasing consumption of fossil fuels resulting from rapidly growing population and industrialization has caused the adverse effects on terrestrial ecosystems and become one of the most serious problems causing environmental discriptions. Air pollution such as $SO_2, HF, NO_X,$ fly ash, ozone and PAN might influence plant growth, reproduction, nutrient cycling, photosynthesis and predisposition to entomological and pathological stresses on plants. Furthermore, accumulation of those toxic substances in forests might cause subtle or serious changes in the structure and function of forest ecosystems. Since 1970s, a number of large industrial complexes had been constructed as a part of industrialization plan in Korea. Accordingly, the forest exosystems around them has been under chronic influences of air pollution and effects of air pollution on plants became a matter of concern. In Yocheon Industrial Complex which consisted of lots of petrochemical plants and a phosphatic fertilizer manufacturing plant, forests has been exposed to chronic air pollution, mainly HF and $SO_2$ gas, Various reports were available to investigate the potential effects of air pollution on crops and forest trees in Yocheon. Kim and Kim surveyed vegetation by naked eye method and reported 71 families, 150 genera and 158 species were growing within a 2 km from air pollution sources in 1981. Needle injuries on Pinus spp. in the polluted area water reported by Kim, et al. and Kim, et al. Kim, et al. investigated the primary production of Pinus thunbergii forests in the polluted area and verified that growth inhibition of Pinus thunbergii was attributable to air pollution. Thus, previous reports suggested that forest ecosystems around Yocheon Industrial Complex were influenced adversely by air pollution. The objective of this study was to investigate the subtle ecological changes in forest community exposed to chronic air pollution in Yocheon.

• 설비공학논문집
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• 제16권5호
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• pp.397-407
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• 2004

It is well known that some key parameters, such as evaporating temperature, refrigerant mass flow rate, face velocity and inlet air temperature, have significant influence on the evaporator performance. However performance studies related to a humid environment have been very scarce. It is demonstrated that the refrigerant mass flow rate, heat flux, water condensing rate and air outlet temperature of the evaporator significantly increase with air inlet relative humidity. As the air inlet relative humidity increases, the latent and total heat transfer rates increase, but the sensible heat transfer rate decreases. The purpose of this study is to provide experimental data on the effect of air inlet relative humidity on the air and refrigerant side pressure drop characteristics for a slit fin-tube heat exchanger. Experiments were carried out under the conditions of inlet refrigerant saturation temperature of 7 $^{\circ}C$ and mass flux varied from 150 to 250 kg/$m^2$s. The condition of air was dry bulb temperature of 27$^{\circ}C$, air Velocity Varied from 0.38 to 1.6 m/s. Experiments Showed that air Velocity decreased 8.7% on 50% of relative humidity 40% of that at degree of superheat of 5$^{\circ}C$, which resulted that pressure drop of air and refrigerant was decreased 20.8 and 8.3% for 50% of relative humidity as compared to 40%, respectively.

• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.596-601
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• 2006

Because of insufficiency of energy resources and pollution of environment, it is necessary to develop alternative energy sources. Nuclear fission energy is used widely for source of electric Power but being restricted due to radioactivity problem. Nuclear fission is highlighted as the new generation of nuclear energy and researched worldwide because of low risk of radiation effect. The representatives of fusion research is China's EAST, KSTAR of Korea and ITER of world. Korea Superconducting Tokamak Advanced Research(KSTAR) project is on progress for the completion in August, 2007. In this study, the research of utility system for KSTAR be carried out. The utility system of KSTAR is consist of water cooling & heating system, $N_2$ gas system, DI water system, service water system and instrument air & auto control system. The progress of KSTAR utility system is under commissioning state after construction completion. The optimal operation scenario will be verified during commissioning and adopted to the KSTAR operation.

• 한국물환경학회지
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• 제30권5호
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• pp.491-502
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• 2014

As meteorology is the driving force for lake thermodynamics and mixing processes, the effects of climate change on the physical limnology and associated ecosystem are emerging issues. The potential impacts of climate change on the physical features of a reservoir include the heat budget and thermodynamic balance across the air-water interface, formation and stability of the thermal stratification, and the timing of turn over. In addition, the changed physical processes may result in alteration of materials and energy flow because the biogeochemical processes of a stratified waterbody is strongly associated with the thermal stability. In this study, a novel modeling framework that consists of an artificial neural network (ANN), a watershed model (SWAT), a reservoir operation model(HEC-ResSim) and a hydrodynamic and water quality model (CE-QUAL-W2) is developed for projecting the effects of climate change on the reservoir water temperature and thermal stability. The results showed that increasing air temperature will cause higher epilimnion temperatures, earlier and more persistent thermal stratification, and increased thermal stability in the future. The Schmidt stability index used to evaluate the stratification strength showed tendency to increase, implying that the climate change may have considerable impacts on the water quality and ecosystem through changing the vertical mixing characteristics of the reservoir.

• 한국대기환경학회:학술대회논문집
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• 한국대기환경학회 2002년도 춘계학술대회 논문집
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• pp.159-160
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• 2002

Soil dust particles transported from loess regions of the Asian continent, called Asian dust, highly influences the air quality of north-eastern Asia and the northern Pacific Ocean. The effects of these dust storms, on the chemical composition of atmospheric aerosol particles with different size, was investigated. Measurements of size distributions of total aerosol and major ion species were carried out on Jeju Island, Korea. (omitted)

• 한국습지학회지
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• 제22권3호
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• pp.178-186
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• 2020

본 연구에서는 낙동강 주요 지류의 기온과 수온 자료를 이용하여 탄성도를 산정하고 수온의 민감도 분석을 수행하였다. 탄성도에 대한 신뢰구간 추정과 가설검증이 가능한 비모수 기반의 탄성도 해석기법을 개발하여 기존 중간값을 이용하는 기법과 비교하고 적용성을 검토하였다. 계절적으로 겨울의 탄성도가 낮고 여름과 가을의 탄성도가 높은 것으로 분석되어 기온의 변동에 따른 수온 및 수질의 변동이 클 것으로 분석되었다. 공간적으로 하수처리장 방류수, 중소 축사의 가축폐수, 소규모 공장의 오·폐수 등 인위적인 요인의 영향을 받는 금호강 지역의 탄성도가 낮은 경향을 나타내고 있다. 낙동강 주요 지류의 탄성도는 약 이상이고 유의수준 5%에서 타당하므로 기후변화에 따른 기온-수온 변동이 큰 것으로 분석되었다.

• Journal of Korean Society for Atmospheric Environment
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• 제17권E2호
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• pp.43-51
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• 2001

A report by the national research council in the United States suggested that many lung cancer deaths each year be associated with breathing radon in indoor air. Most of the indoor radon comes directly from soil beneath the basement of foundations. Recently, radon released from groundwater is found to contribute to the total inhalation risk from indoor air. This study presents the quantitative assessment of human exposures to radon released from the groundwater into indoor air. At first, a three-compartment model is developed to describe the transfer and distribution of radon released from groundwater in a house through showering, washing clothes, and flushing toilets. Then, to estimate a daily human exposure through inhalation of such radon for an adult. a physiologically-based pharmacokinetic(PBPK) model is developed. The use of a PBPK model for the inhaled radon could provide useful information regarding the distribution of radon among the organs of the human body. Indoor exposure patterns as input to the PBPK model are a more realistic situation associated with indoor radon pollution generated from a three-compartment model describing volatilization of radon from domestic water into household air. Combining the two models for inhaled radon in indoor air can be used to estimate a quantitative human exposure through the inhalation of indoor radon for adults based on two sets of exposure scenarios. The results obtained from the present study would help increase the quantitative understanding of risk assessment issues associated with the indoor radon released from groundwater.

• Nuclear Engineering and Technology
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• 제33권5호
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• pp.526-538
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• 2001

Fatigue tests in air and in room temperature water were performed to obtain comparable data and stable crack measuring conditions. In air environment, fatigue crack growth rate was increased with increasing temperature due to an increase in crack tip oxidation rate. In room temperature water, the fatigue crack growth rate was faster than in air and crack path varied on loading conditions. In simulated light water reactor (LWR) conditions, there was little environmental effect on the fatigue crack growth rate (FCGR) at low dissolved oxygen or at high loading frequency conditions. While the FCGR was enhanced at high oxygen condition, and the enhancement of crack growth rate increased as loading frequency decreased to a critical value. In fractography, environmentally assisted cracks, such as semi-cleavage and secondary intergranular crack, were found near sulfide inclusions only at high dissolved oxygen and low loading frequency condition. The high crack growth rate was related to environmentally assisted crack. These results indicated that environmentally assisted crack could be formed by the Electrochemical effect in specific loading condition.

• Environmental Engineering Research
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• 제21권4호
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• pp.427-435
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• 2016

In this study, change in water-dissolved oxygen (DO) was analyzed under various synthetic water qualities and nanobubbles (NBs) application conditions, such as gas type, initial DO as well as water dissolved, suspended and organic matters contents. When oxygen, rather than air, was introduced into nitrogen-desorbed ultra-pure water, the stagnation time was significantly increased. It took ten days for DO concentration to drop back to saturation. The higher the initial DO concentration, the longer particles were observed above saturation due to particle stability improvement. The oxygen mass transfer rate of 0.0482 mg/L/min was found to reach a maximum at an electrolytic concentration of 0.75 g/L, beyond which the transfer rate decreased due to adsorption of negative ions of the electrolyte at the interface. High levels of turbidity caused by suspended solids have become a barrier to dissolution of NBs oxygen into the water solution, and thus affected the transfer performance. On the other hand, by applying NBs for just an hour, up to 7.2% degradation of glucose as representative organic matter was achieved. Thus, NBs technology would maintain a high DO extent for an extended duration, and thus can improve water quality provided that water chemistry is closely monitored during its application.

• 설비공학논문집
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• 제20권4호
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• pp.287-293
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• 2008

The purpose of this study was to clarify the effects of air and ceiling temperatures on a type of ceiling cooling system that involves cool water circulation. The experiment is conducted in summer. The subjects (11 young females) are exposed to the following conditions: combinations of air temperatures $(27^{\circ}C,\;29^{\circ}C,\;31^{\circ}C)$ and ceiling temperature of $(22.7^{\circ}C,\;23.7^{\circ}C,\;24.7^{\circ}C)$ in still air and RH 50%. The following results were obtained; the thermal sensation vote is neutral at a mean skin temperature of $34.5^{\circ}C$. The ceiling temperature affected different parts of the body. For example, the forehead, scapula and abdomen produced different skin temperatures. Thermal comfort vote was rated as comfortable at high temperature environment. The satisfaction from the ceiling temperature was valued comfortable zone in this experiment. Mean skin temperature showing higher thermal neutrality temperature than existing studies for floor and wall radiation cooling results.