• Journal of Korean Society on Water Environment
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• v.28 no.6
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• pp.933-942
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• 2012

The purpose of this study is to evaluate the degree of waterbody impairment according to the flow conditions and present to the appropriate water quality improvement alternatives using observed water quality and flow for Total Maximum Daily Load (TMDL) implementation at 39 unit watersheds the nakdong river basin. Observed water quality data for 7 years are divided into five cumulative flow frequency group and comparing the each observed water quality data and TMDL Target water quality (TWQ) the last evaluate the water quality is impaired group. We found that the cumulative flow frequency group-specific the average excess rate of V group was the highest (32.86%), followed by the IV group (26.04%), group III (23.36%), II group (22.67%), I group (20.70%), the degree of impaired waterbody tended to be inversely proportional to the flow rate. Resulted from cumulative flow frequency group of impaired water quality assessment, 13 unit watersheds are impaired from a group IV and group V affected by point sources. Therefore, improvement of sewage discharge and the initial composition of the riparian buffer zone are needed. Nakbon F, Namkang D and Namkang E within 13 unit watersheds are impaired from group II and III affected by non-point sources. Therefore, application of Best Management Practices (BMPs) is needed for these watersheds. Evaluation of impaired waterbody using Cumulative flow frequency group is able to determine the extent of the judgment to TWQ exceeded by the flow conditions and helps proper setting Standard flow and planning pollutant reduction for TMDL.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.12
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• pp.655-663
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• 2017

It is difficult to manage hotspot area and to establish the reduction plan considering with spatial-distribution on Korea TMDLs (Total Maximun Daily Loads) system. To solve this problems, methods of Load Duration Curve (LDC) using long-term flow and water quality data, and spatial-analysis were applied on present TMDLs. Jinwi A watershed which is enforced TMDLs plan were selected to study area. Results of application of suggested methods in this study to Jinwi watershed, Hwangguji tributary was selected to hotspot area and Jinwi tributary was exclued. Also, middle area of Hwangguji tributary was needed a reduction plan for the protection of non-point source pollution. In downstream area, livestock manure should be managed additionally. The new methods suggested in this study were useful to increase healthiness for total watershed.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.5
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• pp.188-194
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• 2005

The direct injection diesel engine is one of the most efficient thermal engines. For this reason DI diesel engines are widely used for heavy-duty applications. But the world is faced with very serious problems related to the air pollution due to the exhaust emissions of diesel engine. So, that is air pollution related to exhaust gas resulted from explosive combustion should be improved. Exhaust Gas Recirculation(EGR) is a proven method to reduce NOx emissions. In this study, the experiments were performed at various engine loads while the EGR rates were set from $0\%$ to $30\%.$ The emissions trade-off and combustion of diesel engine are investigated. The brake specific fuel consumption rate is very slightly fluctuated with EGR in the range of experimental conditions. The ignition delay increased with increasing EGR rate. The maximum value of premixed combustion for the rate of heat release is increased with increasing EGR rate. NOx emissions are decreased with increasing EGR rate at high load and high speed. It was found that the exhaust emissions with the EGR system resulted in a very large reduction in oxides of nitrogen at the expense of higher smoke emissions.

• Journal of Korean Society on Water Environment
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• v.23 no.5
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• pp.766-775
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• 2007

The use of toxic chemicals was extended as the industry in Korea has grown dramatically during the last three decades. However, list of toxic substances and limit concentrations in the water environment are not consistent within management of ambient water, drinking water and industrial effluent. This article suggests the systematic framework to classify toxic substances in the water environment and deriving their effluent limits. The most important factor for decision-making to classify toxic substances is whether their concentrations in the water environment are higher than the reference concentrations, estimated by considering human health risk and ecological risk. Using a risk-based reference concentration, the ambient water quality criterion, it is possible to derive the regulatory limit concentrations of toxic substances in drinking water and in industrial effluent. The goal concentrations in the effluent, which guarantee the human and ecological safety, should be determined with scientific investigation, balancing environmental benefit and economical effect, considering availability of treatment technology and identifying characteristics of wastewater from different industries.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.313-313
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• 2021

남·북한강 상류 수계에는 만대지구, 가아지구, 자운지구, 도암호유역, 골지천유역, 대기지구 등 총 6개의 비점오염원관리지역이 지정되어 있으며, 비점오염원관리를 위한 관리대책 및 시행계획에 따라 지속적으로 비점오염저감시설이 설치·운영되고 있다. 그러나, 기후변화에 따른 집중호우 등의 원인으로 뚜렷한 비점오염 저감효과가 나타나지 않고 있으며, 개별 비점오염 저감시설의 명확한 저감효율이 정량화되지 않아 탁수저감 기여도 및 효율성 평가 시 한계가 있다. 따라서 본 연구에서는 문헌연구를 통하여 비점오염저감시설별 저감효율 제시가 미흡하였던 시설 중 돌망태, 식생토낭에 대해 실험을 진행하였다. 저감효율 평가를 위해 경사도 3%, 사면 폭 4 m, 사면길이 22 m의 시험포를 조성하였다. 강우시 발생하는 유출수를 대조구와 비교하였으며, 영농시기를 고려하여 영농작업을 병행하여 실시하였다. 제거효율법을 통한 저감효율 산정 결과 돌망태와 식생토낭의 SS항목은 80.5%와 73.7%로 저감효율이 가장 높은 것으로 나타났으며, BOD는 71.2%, 60.2%, T-N은 70.5%, 64.7%, T-P는 63.7%, 63.1%로 나타났다. TOC는 46.8%, 38.8%로 다른 항목에 비해 상대적으로 낮은 저감효율이 나타났다. 부하량합산법을 통한 저감효율 산정 결과 돌망태와 식생토낭의 T-N 항목은 78.6%와 70.8%로 저감효율이 가장 높은 것으로 나타났으며, BOD는 77.5%, 65.4%, SS는 76.7%, 67.8%, T-P는 68.4%, 63.7%로 나타났다. TOC는 62.7%, 44.6%로 시설별 뚜렷한 차이가 나타났다. 제거효율법과 부하량합산법을 이용하여 저감효율을 분석한 결과 모든 항목에서 40%이상의 저감효율이 나타났으며, 돌망태가 식생토낭에 비해 저감효과가 좋은 것으로 분석되었다. 경사면의 흙탕물 저감을 위해서는 비점오염저감시설의 설치가 우선되어지나, 탁수저감 기여도 및 저감효율 제시를 위한 정량화는 장기간의 모니터링이 필요하기 때문에 지속적인 모니터링을 통한 효율평가가 이루어져야 할 것으로 판단되며, 본 연구 결과는 향후 비점오염저감시설 설치에 따른 유역 내 오염물질 발생 모의를 위한 모델링의 기초차료로 활용될 수 있을 것으로 기대된다.

• Fisheries and Aquatic Sciences
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• v.6 no.3
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• pp.149-154
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• 2003

The characteristics of pollutant loads from the various sources and seawater quality in Kwangyang Bay were evaluated. Total flow rate was estimated to be $10,868,066.8 m^3/day$ with a flow rate of R2l (the Seomjin River) as the highest one. Total COD, TN and TP loads of the input rivers and the ditches were about 27,591.8, 25,029.6 and 586.4 kg/day, respectively. Wastewater discharging loads was the greatest contributors to pollutant loads in the inner part of Kwangyang Bay. COD values in the inner part of the bay was over 3.0 mg/L, which exceeded the seawater quality criteria III of Korea. The average values of DIN and DIP were 8.62 ${\mu}gN/L\;and\;1.26\;{\mu}gP/L$, respectively. The limiting factor for algal growth was DIN. In he total discharging loads of the watershed from unit loading estimations, BOD, TN and TP were 9,132.3, 2,727.2 and 304.2 kg/day, respectively. In addition, municipal sewage by the population as pollution sources and the city of Kwangyang as administrative district had the highest loads. For a appropriate water quality recovery of Kwangyang Bay, it is suggested that it is essential to estimate reduction rate of total pollutant loads by water quality modeling.

• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.256-262
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• 2011

Environmental pollution by Using of a fossil fuel, a reckless and growth-oriented development since the Industrial Revolution has caused global change of environment. An issue largest among this is a climate change. A global mean temperature since 19th century has climbed up $0.4{\sim}0.8^{\circ}C$. After The Kyoto Protocol regarding a greenhouse gas reduction goal took effect, be situations that decrease of greenhouse gas was acutely required. Interest of utilization of the new & renewable energy is increasing every day. This study shows that at first divided a country to nine range by natural geography, and second executed Meteorological data analysis of recent 30 years considering level of significance by nine range. The results of this study are that in heating load calculation of building, periodic temperature data management is required because facility capacity and cost are affected greatly by outdoor temperature, and temperature by climate range needs consideration of pertinent area. Lastly, ground temperature was assumed of the weather in region, the ground and soil.

• Journal of the Korean Society of Marine Environment & Safety
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• v.13 no.2 s.29
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• pp.103-110
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• 2007

This study estirmted the appropriate pollutant load reduction from point sources in Jinhae Bay, Korea, using an eco system model. The results of COD values in the inner part of the bay obtained through the simulation by ecosystem model were greater than 3.0mg/L, and exceeded the limits of Korean Coastal Water Quality Grade III. Engineering countermeasures to reduce the $70\sim90%$ of all land based pollution load or organic and inorganic material loads from point sources by more than 50% were required to keep the COD levels below 2 mg/L. The reduction loads is 5,632kg/day of COD, 481kg/day of DIP and 7,991 kg/day of DIN in case of the reduction of both the organic and nutrients. The estimated environmental currying capacity of that case is 13,112kg/day of COD, 206kg/day of DIP and 3,425kg/day of DIN to keep the COD levels below 2mg/L.

• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.3
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• pp.35-40
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• 2007

Our environment is faced with serious problems related to the air pollution from automobiles in these days. In particular, the exhaust emissions of diesel engine are recognized main cause which influenced environment strong, In this study, the potential possibility of biodiesel fuel was investigated as an alternative fuel for a naturally aspirated common rail diesel engine. The smoke emission of biodiesel fuel 5vol-%(min. content) was reduced in comparison with diesel fuel, that is, it was reduced approximately 60% at 4000rpm, full load. But, power, torque and brake specific energy consumption didn't have no large differences. But, NOx emission of biodiesel fuel was increased compared with a commercial diesel fuel. Also, the effects of exhaust gas recirculation(EGR) on the characteristics of NOx emission has been investigated. It was found that simultaneous reduction of smoke and NOx was achieved with biodiesel fuel(5vol-%) and cooled EGR method($5{\sim}10%$) in a common rail diesel engine.

• Transactions of the Korean Society of Automotive Engineers
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• v.13 no.2
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• pp.65-71
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• 2005

Our environment is faced with serious problems related to the air pollution from automobiles in these days. In particular, the exhaust emissions of diesel engine are recognized main cause which influenced environment strong. In this study, the potential possibility of biodiesel fuel was investigated as an alternative fuel for a naturally aspirated D.I. diesel engine. The smoke emission of biodiesel fuel was reduced remarkably in com parison with diesel fuel, that is, it was reduced approximately 48.5% at 2500rpm, full load. But, power, torque and brake specific energy consumption didn't have no large differences. But, $NO_X$ emission of biodiesel fuel was increased com pared with commercial diesel fuel. Also, the effects of exhaust gas recirculation(EGR) on the characteristics of $NO_X$ emission has been investigated. It was found that simultaneous reduction of smoke and $NO_X$ was achieved with biodiesel fuel(20vol-%) and cooled EGR method($5{\sim}15%$).