• Korean Journal of Environmental Agriculture
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• v.16 no.3
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• pp.274-284
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• 1997

Pesticide runoff from crop fields is the important concern in environment because it may affect aquatic ecosystem and human. And it is essential to find out the amount of runoff and evaluate the possible effect on aquatic organisms for the human and environmental risk assessment. However, no definite guidelines have been established and related researches are not active in Korea since too many factors were involved in pesticide runoff and it was hard to predict it by using simple data. Therefore, various runoff studies with natural field, simulated rain/field, and computer models were reviewed for the general aspect of experiments and results.

• Environmental Analysis Health and Toxicology
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• v.18 no.4
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• pp.255-269
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• 2003

The objective of this study was to estimate human exposure to benzo (a)pyrene through multimedia/multi-pathway exposure scenario. The human exposure scenario for benzo(a)pyrene was consisted of 12 multiple exposure pathways, and the multipathway human exposure model based on this scenario constituted. In this study, the multipathway human exposure model was used to estimate the concentrations in the exposure contact media, human intake factors and lifetime average daily dose (LAD $D_{model}$) of benzo(a)pyrene in the environment. Sensitivity analysis was performed to identify the important parameters and Monte-Carlo simulation was undertaken to examine the uncertainty of the model. The total LAD $D_{model}$ was estimated to be 5.52${\times}$10$^{-7}$ mg/kg-day (2.06${\times}$10$^{-7}$ -8.65${\times}$10$^{-7}$ mg/kg-day) using the multipathway human exposure model. The inhalation dose accounted for 78% of the total LADD, whereas ingestion and dermal contact intake accounted for 20.2% and 1.8% of the total exposure, respectively. Based on the sensitivity analysis, the most significant contributing input parameter was benzo (a)pyrene concentration of ambient air. Consequently, exposure via inhalation in outdoor/indoor air was the highest compared with the exposure via other medium/pathways.

• Journal of the Korean Chemical Society
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• v.42 no.4
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• pp.378-382
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• 1998

A Quantitative Structure-Activity Relationship of 1-phenylcyclohexyl amine(PCA) and dexoxadral as a receptor has been investigated using semiempirical PM3 MO and Hyper Chem calculation. A set of 19 analogues of PCA was chosen for the study using a selection procedure aimed at minimizing the interparameter correlations, while ensuring that the frontier orbital covered the maximum possible range of LogP. The results show that the FOS and LogP is a good structural parameter to predict the maximum electroshock effective dose ($MES\;ED_{50}$) and toxicity dose ($TD_{50}$) for PCA derivatives.

• Environmental Analysis Health and Toxicology
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• v.17 no.3
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• pp.187-195
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• 2002

다환방향족탄화수소류 화합물의 증기상-입자상간의 분배평형의 설명을 위해 흔히 입자상의 흡착지점이 균질하고 총흡착면적은 TSP에 비례한다는 가정을 사용하는데 본 연구의 목적은 이러한 가정의 타당성을 평가하는 것이다. 본 연구를 위해 도심에서 6단의 다단계 대기중입자채집기를 사용하여 대기 중의 입자를 포집하였으며 이들 입자에 흡착된 phenanthrene, anthracene, fluoranthene, pyrene을 분석하여 입경별 분포를 측정하였다. 특히 연구기간 중에 황사현상이 일어나 입경분포나 입자의 기원이 매우 다른 경우에 대한 연구가 가능하였다. 주요연구결과로서 우선 야마사키가 제안한 분배평형의 온도 의존식은 제한된 범위에서 사용되어야 한다는 것이 관측되었다. 즉, 황사현상이 일어나는 경우와 같이 입자의 흡착특성과 입경분포가 보통때와 다른 경우에는 log Kp와 l/T의 관계에서 선형성이 상당히 저하되었다. 또한 특히 낮은 온도에서는 입자의 입경분포가 달라지면 전체적인 분배평형이 달라지게 되는 것으로 평가되었으며 입자의 흡착특성도 분배평형의 온도의존성에 결정적인 영향을 줄 수 있는 것으로 나타났다. 따라서 입자의 기원이 다양하거나 입경분포가 달라지면 흡착평형이 바뀌기 때문에 흡착특성의 균질성과 단순한 TSP를 전제로 하는 분배평형의 평가나 예측은 실제 대기조건에서는 정확하지 않을 수가 있으며 제한적인 조건에서 사용되어야 할 것이다.

• Environmental Analysis Health and Toxicology
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• v.17 no.3
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• pp.225-238
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• 2002

유해물질의 거동에 대한 이해를 돕기 위해서 대도시지역을 대상으로 하여 fugacity를 이용한 level-III 다매체환경거동모형이 개발되었다. 이 모형에 의한 거동의 예측결과에 민감한 영향을 주는 입력과정과 변수들을 찾아내기 위하여 체계적으로 민감도분석을 수행할 수 있도록 하는 기법을 개발하고 사례연구로서 서울지역과 2, 3, 7, 8-TCDD을 대상으로 그 기법을 적용하였다. Sensitivity index에 의한 평가한 결과, 일정한 배출속도조건에서는 대기중의 바람속도, 그리고 대기에서 수체나 토양으로 전이되는 건식 및 습식 침적과정이 다매체거동에서 전체적으로 가장 중요한 과정인 것으로 나타났다. 또한 이들 거동과정 자체에 영향을 미치는 변수들에 대한 민감도 분석의 결과 건식침적의 경우 중력에 의한 입자들의 침강속도가, 습식침적의 경우 평균 강우속도가 대단히 중요한 변수임이 파악되었다. 물질의 물리화학적 특성 가운데에서는 z-값에 직접 영향을 주는 변수들, 즉, 헨리상수와 옥타놀-물 분배계수 등이 결과에 민감한 영향을 주는 것으로 나타났다. 이러한 사례연구는 본 연구에서 개발된 민감도분석기법이 유해물질의 다매체 거동모형을 개선하고 좀더 중요한 거동과정에 대한 이해를 넓히는데 효율적으로 사용될 수 있다는 것을 보여주고 있다.

• Journal of the Korean Institute of Gas
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• v.18 no.5
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• pp.85-90
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• 2014

Turbo chiller is widely used for the air conditioner and uses hydrochlorofluorocarbon 123 (HCFC-123) as a refrigerant. HCFC-123 is one of the chemicals being considered as a replacement for the chlorofluorocarbons. High concentrations of HCFC-123 cause a deficiency of oxygen with the risk of unconsciousness or death, the vapour is heavier than air and may accumulate in low ceiling spaces causing deficiency of oxygen. In this study, the concentration distribution of oxygen indoor was investigated by using computational fluid dynamics(CFD) as four workers were killed in HCFC-123 gas leaks at machine room of hypermarket in 2011.

• Journal of Korean Society of Transportation
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• v.20 no.7
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• pp.155-166
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• 2002

Since 1990s. there has been an increasing number of traffic accidents at intersection. which requires more urgent measures to insure safety on intersection. This study set out to analyze the road conditions, traffic conditions and traffic operation conditions on signalized intersection. to identify the elements that would impose obstructions in safety, and to develop a traffic accident prediction model to evaluate the safety of an intersection using the cop relation between the elements and an accident. In addition, the focus was made on suggesting appropriate traffic safety policies by dealing with the danger elements in advance and on enhancing the safety on the intersection in developing a traffic accident prediction model fir a signalized intersection. The data for the study was collected at an intersection located in Wonju city from January to December 2001. It consisted of the number of accidents, the road conditions, the traffic conditions, and the traffic operation conditions at the intersection. The collected data was first statistically analyzed and then the results identified the elements that had close correlations with accidents. They included the area pattern, the use of land, the bus stopping activities, the parking and stopping activities on the road, the total volume, the turning volume, the number of lanes, the width of the road, the intersection area, the cycle, the sight distance, and the turning radius. These elements were used in the second correlation analysis. The significant level was 95% or higher in all of them. There were few correlations between independent variables. The variables that affected the accident rate were the number of lanes, the turning radius, the sight distance and the cycle, which were used to develop a traffic accident prediction model formula considering their distribution. The model formula was compared with a general linear regression model in accuracy. In addition, the statistics of domestic accidents were investigated to analyze the distribution of the accidents and to classify intersections according to the risk level. Finally, the results were applied to the Spearman-rank correlation coefficient to see if the model was appropriate. As a result, the coefficient of determination was highly significant with the value of 0.985 and the ranks among the intersections according to the risk level were appropriate too. The actual number of accidents and the predicted ones were compared in terms of the risk level and they were about the same in the risk level for 80% of the intersections.

• Journal of the Korean Institute of Gas
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• v.16 no.4
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• pp.38-43
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• 2012

The purpose of this study is to carry out the consequence analysis of an accident related to the release of Hydrogen chloride occurred in a petrochemical company in Korea and suggest the measures to prevent similar accidents from happening again. The total amount released through the safety valve of HCl Column was calculated based on the rated capacity of the safety valve, the ideal gas equation and mechanical energy balance, respectively. As a result of the calculation, we found that the amount of HCl released through the safety valve was at least 76.8 kg. Also, we predicted the dispersion concentration at the position of the injured workers(more than 350 m away from the accident location) using simulation programs such as PHAST. The results of ALOHA and K-CARM are 304 ppm and 1,700 ppm respectively. However, PHAST calculation indicated that the concentration is less than l ppm. From these results, we can understand that workers were injured by HCl gas released from the safe valve and the concentration of gas might be less than 1 ppm. Also, it is important for toxic gases such as HCl to be vented safely to the atmosphere after scrubbing.

• Journal of Food Hygiene and Safety
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• v.17 no.3
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• pp.137-145
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• 2002

Tributyltin compounds have been increasingly used in the form of plastic stabilizers, catalytic agents, industrial agricultural biocides, antifouling paint, and pesticides. Among these organotin compounds, large amounts of tributyltin(TBT) and triphenyltin(TPT) have been used as antifouling agents because they have a superior ability to prevent marine organism from being encrusted on ship bottoms and in culturing nets. Environmental pollution by these organotin compounds in the aquatic environment were undertaken. The international maritime Organization's established a provisional tolerable daily intake(TDI) of 1.6[micro]g TBTO/kg/ B.W. The Food and Agiculture Organization (of the United Nations)/world Health Organization's (FAO/WHO) proposed a TDI of 0.5ug TPT/kg BW/d. This study is conducted monitoring of TBT on seafoods in Korea and risk assessment for exposure on TBT in seafoods. Total hazard index(using Reference Dose : 0.3 ug TBTO/kg B.W/day) of intake exposure on seafoods is 0.04 as the 50th percentile, 0.08 as the 95th percentile. This value is estimated by Monte-Carlo simulation using Crystal Ball(Decisioneering Co., 2001).

• Journal of the Korea Society for Simulation
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• v.33 no.1
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• pp.1-17
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• 2024

Forest management is known to beneficially influence stand structure and wood production, yet quantitative understanding as well as an illustrative depiction of the effects of different management approaches on tree growth and stand dynamics are still scarce. Long-term management of beech forests must balance public interests with ecological aspects. Efficient forest management requires the reliable prediction of tree growth change. We aimed to develop a novel hybrid simulation approach, which realistically simulates short- as well as long-term effects of different forest management regimes commonly applied, but not limited, to German low mountain ranges, including near-natural forest management based on single-tree selection harvesting. The model basically consists of three modules for (a) natural seedling regeneration, (b) mortality adjustment, and (c) tree growth simulation. In our approach, an existing validated growth model was used to calculate single year tree growth, and expanded on by including in a newly developed simulation process using calibrated modules based on practical experience in forest management and advice from the local forest. We included the following different beech forest-management scenarios that are representative for German low mountain ranges to our simulation tool: (1) plantation, (2) continuous cover forestry, and (3) reserved forest. The simulation results show a robust consistency with expert knowledge as well as a great comparability with mid-term monitoring data, indicating a strong model performance. We successfully developed a hybrid simulation that realistically reflects different management strategies and tree growth in low mountain range. This study represents a basis for a new model calibration method, which has translational potential for further studies to develop reliable tailor-made models adjusted to local situations in beech forest management.