• Proceedings of the Korea Water Resources Association Conference
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• 2023.05a
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• pp.486-486
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• 2023

하수처리장 내 생물반응조에서는 유기물을 제거하거나 질산화(Nitrification) 반응을 일으키기 위하여 산소를 요구하고 있으며, 필요한 산소는 송풍기 운영을 통해 공급하고 있는 상황이다. 질산화 반응을 일으키기 위해서 처리장 내 일정 이상의 산소가 수중에 공급되어야 한다. 생물반응조내 용존산소가 부족할 경우 활성슬러지의 침전성이 저해되어 오염물질 저감 효율이 떨어지게 되며, 과도한 산소가 공급되어도 수처리의 효율은 개선되지 않으며 반응에 사용되지 않은 산소들은 대기중으로 방출된다. 또한 유입수질에 따라 실시간으로 반응조 내 필요한 산소는 달라지게 되므로 유입수질에 맞는 효율적인 하수처리장 운영이 요구되고 있다. 하수처리장 내 적절한 산소를 공급하기 위하여 많은 연구들이 활발하게 진행되어 왔으나 실제생물학적 처리시 요구되는 산소의 양을 산정할 수 있는 한계점을 지니고 있으며, 하수 성분, 용량과 같은 환경에 따라 차이를 보이고 있어 범용적으로 사용하기에는 어려움이 있다. 따라서 본 연구에서는 이러한 적용 한계점을 극복하기 위하여 하수도 설계 시 사용되어지고 있는 하수도 시설기준의 산소요구량 및 공기공급량 산정식을 통하여 유입수질에 따라 실제 하수처리장에 필요한 산소요구량 & 공기공급량을 산정하는 시스템을 개발하고자 하였다. 하수도 설계기준의 여러 가지 수식을 실제 하수처리장 내 필요한 요소로 변환시켜 범용적으로 사용가능한 시스템을 개발하였다. 본 연구에서 개발한 하수처리장 송풍량 산정 시스템 적용에 따른 송풍량 절감 효율을 비교분석하기 위하여 2021년 A하수처리장의 4월 월간 데이터를 활용하여 하수처리장에서 필요한 송풍량을 산정하여 실제 사용된 송풍량과 비교 분석하여 송풍량 절감 효율을 분석하였다. 본 연구의 결과를 바탕으로 실제 하수처리장 내 송풍량 산정 시스템을 도입하게 된다면 운전자 경험에 의존하고 있는 수동적인 제어 방식에서 벗어나 자율 제어를 통한 효율적인 하수처리장을 운영할 수 있어 송풍량 절감 및 탄소중립에도 이바지 할 수 있을 것이라고 판단된다.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.464-464
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• 2021

우리나라는 최근 도시지역의 광역화로 인해 시가화 지역이 지속적으로 증가하고 있으며, 이로 인해 증가한 불투수면적은 이수 및 치수 측면에서 다양한 문제를 야기하여 유역의 물순환 체계를 왜곡하고 있다. 더불어 하천의 건천화에 따른 하천 유지유량의 감소 및 공공수역으로 방출되는 오염물질의 증가는 하천의 다양한 환경적, 생태학적 문제를 야기하고 있다. 따라서 최근에는 유역 물순환 관리가 국가 물관리 정책의 핵심 전략으로 부각되고 있으며, 적절한 물순환 관리를 위해서는 물순환 건전성이 취약한 우선관리 유역을 도출하고, 해당 유역을 중심으로 보다 체계적이고 통합적인 유역관리 기술이 필요하다. 따라서 본 연구에서는 유역 물순환에 영향을 미치는 주요 요소들을 기후, 수문, 수질 및 사회·경제적 요인 측면으로 구분하고, Pressure-State-Response (PSR) framework를 적용하여 각 요소 별 주요 평가 지표들을 압력 (Pressure), 상태 (State) 및 반응(Reponse) 요인으로 분류하였다. 또한 전국 소권역 단위에 대하여 각 지표들을 분석하여 기후, 수문, 수질 및 사회·경제적요인 별 물순환 건강성 점수를 산정하였다. 한편, 지역 및 요인별 물순환 건강성 점수를 기반으로 핫스팟 분석 (Hot Spot Analysis)을 수행하여, 통계적으로 유의미한 패턴을 나타내는 지역을 중심으로 우선관리가 필요한 지역을 도출하였다. 본 연구에서 도출한 물순환 건강성 평가 요소별 점수 및 핫스팟 분석 결과는 향후 물순환 우선관리 지역 선정에 있어 기초자료로 활용될 수 있을 것으로 기대된다.

• Membrane Journal
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• v.33 no.3
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• pp.87-93
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• 2023

Electrodialysis (ED) is essential in separating ions through an ion exchange membrane. The disposal of brine generated from seawater desalination is a primary environmental concern, and its recycling through membrane separation technology is highly efficient. Alkali is produced by several chemical industries such as leather, electroplating, dyeing, and smelting, etc. A high concentration of alkali in the waste needs treatment before releasing into the environment as it is highly corrosive and has a chemical oxygen demand (COD) value. The concentration of calcium and magnesium is almost double in brine and is the perfect candidate for carbon dioxide adsorption, a major environmental pollutant. Sodium hydroxide is essential for the metal carbonation process which, is easily produced by the bipolar membrane electrodialysis process. Various strategies are available for its recovery, like reverse osmosis (RO), nanofiltration (NF), ultrafiltration (UF), and ED. This review discusses the ED process by ion exchange membrane for alkali recovery are discussed.

• Journal of Korean Society of Environmental Engineers
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• v.22 no.6
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• pp.1159-1170
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• 2000

It is necessary to improve the ambient air quality through the proper treatment and control of pollutants by designating air pollutants to regulatory ones. Especially, human took a concern for particulate matters which raised visibility reduction, public health effects and injury of property for urban areas. In order to reduce the effect of particulate matters, we need to establish proper control strategies based on the concentration characteristics of particulate matters. In this study. to evaluate the characteristics of $PM_{2.5}$ and $PM_{10}$. thirty-eight samples of $PM_{2.5}$ and $PM_{10}$ were collected at Nam-Gu sampling site where continuous air monitoring system has been operated, from May, 1999 to November, 1999, and their concentrations for the mass and anion components($Cl^-$, $NO_3{^-}$, $SO_4{^{2-}}$) were analyzed. The important conclusions obtained in this study were as followings. Total average mass concentrations of $PM_{2.5}$ and $PM_{10}$ were 35.016 and $50.293{\mu}g/m^3$ respectively. and $PM_{2.5}/PM_{10}$ ratio was calculated 0.692. Total average concentrations of anion components in $PM_{2.5}$ were $1.581(Cl^-)$, $3.690(NO_3{^-})$ and $12.825(SO_4{^{2-}}){\mu}g/m^3$ and those in $PM_{10}$ were $2.471(Cl^-)$, $5.819(NO_3{^-})$ and $14.414(SO_4{^{2-}}){\mu}g/m^3$ respectively. From the correlations analysis. the correlation coefficient between mass concentration of $PM_{2.5}$ and $PM_{10}$ was calculated as 0.945. The correlation coefficients between $PM_{2.5}$ and anion components were analyzed as $Cl^-$(0.025), $NO_3{^-}$(0.788) and $SO_4{^{2-}}$(0.500) respectively, and the correlation coefficients between $PM_{10}$ and anion components were analyzed as $Cl^-$(-0.019), $NO_3{^-}$(0.806) and $SO_4{^{2-}}$)(0.535) respectively.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.13 no.4
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• pp.151-162
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• 1980

To clarify the dispersion of pollutants introduced in the coastal region, a series of current measurements, the drogue and drift bottle experiments as well as the dye diffusion experiments were carried out in Onsan Bay and in the coastal waters of Ubong-ri near Ulsan. In the southeastern coastal region of Korean peninsula, that is, in the outside of Onsan Bay, the flood tidal current flows south-south-westward, and the ebb current flows north-north-eastward at a maximum speed of 1.0-1.1 knots at spring tide. In an inlet south of Cape Ubong, an anticyclonic eddy of 1 km in diameter is usually formed during both flood and ebb flows. The tidal current predominates in Onsan Bay at around spring tide. The maximum speed around spring tide was observed to be approximately 0.14 knot, while it was slower than 0.1 knot and variable at neap tide when the wind drift current played an important role. The flood tidal current flows westward while the ebb flow flows eastward in the northern region of the bay. The flood tidal current in the southern region of the bay flows west-north-westward, while the ebb current east-north-eastward. Wind drift currents in the coastal region of southern Korea are generally deduced to be southward in winter, the monthly mean speed being approximately 0.1 knot. Dye solution released at the northwestern corner in Onsan Bay was transported by eastward ebb tidal current toward the mouth of the bay dispersing by the wind. The apparent diffusion coefficient at 150 minutes after release in the bay was calculated to be $4.4\times10^4\;cm^2.sec^{-1}$, whereas that in the anticyclonic eddy was more or less smaller.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.401-406
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• 2020

NOx (nitrogen oxide) in the exhaust gas engines causes severe air pollution. NOx is produced under high-temperature combustion conditions. EGR (exhaust gas recirculation) is normally used to reduce the combustion temperature and NOx production. As the EGR ratio increases, the NOx level becomes low. On the other hand, an excessively high EGR ratio makes the combustion unstable resulting in other air pollution problems, such as unburned hydrocarbon and higher CO levels. In this study, the improvement of fuel droplets moving by the radiation of sonic waves was studied for the stable combustion using analytic and experimental methods. For the analytical study, the effects of the radiation of a sonic wave on the fuel droplet velocity were studied using Fluent software. The results showed that the small droplet velocity increased more under high-frequency sonic wave conditions, and the large droplet velocity increased more under low-frequency sonic wave conditions. For the experimental study, the combustion chamber was made to measure the combustion pressure under the sonic wave effect. The measured pressure was used to calculate the heat release rate in the combustion chamber. With the heat release rate data, the heat release rate increased during the initial combustion process under low-frequency sonic wave conditions.

• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.3
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• pp.148-153
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• 2006

This study dealt with the measurement of exhausted gas concentration, the estimation of a combustion efficiency, and the review of IMO indexing. We concentrated on establishing the basic data to take a counterplan coping with $CO_2$ regulations. The average combustion efficiency was 98% in shop test of new engines and 96.5% in sea trial test of new ships, respectively. It would become lower for the old engine or/and ship. High combustion efficiency results in high $CO_2$ emission and low combustion efficiency results in high emission of incomplete combustion products. The efficient method reducing $CO_2$ emission without an increase in noxious air pollutants would be the development of a substitute fuel and the fuel-efficient and economical engine, and the fair play among shipping agencies in a ship speed. In reviewing of IMO indexing, it is necessary to begin by analyzing the carbon content of a marine fuel for a precise estimates.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2006.04a
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• pp.247-252
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• 2006

오염 퇴적물내 중금속의 방출과 이에 따른 생이용성(bioavalability)은 기존의 가역 평형관계로써 설명하기에 불충분한 것으로 알려져 있다. 최근 연구결과에 의하면 이러한 탈착 저항성을 설명하기 위한 비가역적 모델에 의해 퇴적물내 중금속의 탈착저항성 부분이 존재함이 밝혀졌다. 탈착저항성에 대해서는 아직 충분한 규명이 이루어지지 않았으나, 오염물질의 노화(aging)에 의해 일단 탈착저항성을 띠게 되면 생이용성(bioavailability)이 감소되는 것으로 알려져 있다. 본 연구에서는 노화(aging)가 연안 퇴적물 내 납과 카드뮴의 흡/탈착 특성에 미치는 영향을 알아보기 위해 연속 탈착실험과 biphasic 탈착모델을 적용함으로써 납과 카드뮴의 탈착저항성을 규명하고자 하였다. 그리고 연속 추출 실험을 통해서 노화(aging)에 따른 퇴적물 내 납과 카드뮴의 흡착 기작을 규명하고자 하였다. 연속탈착 실험 결과 시간이 경과함에 따라 탈착저항성부분의 크기가 증가하였으며, 연속추출 실험 결과 납의 경우 carbonate fraction에서 추출된 납이 가장 많았으며, 노화(aging) 따라 exchangeable fraction에서 추출된 납이 감소하는 반면 reducible, organic material, residual fraction에서 추출된 납의 양이 증가하였다. 카드뮴의 경우 가장 많은 양이 추출된 단계는 exchangeable fraction이였으며, organic material fraction에서는 카드뮴이 추출되지 않았다. 노화(aging) 따라 reducible fraction과 residual fraction에서의 추출량이 증가하는 경향을 보였으나 그 양은 매우 적은 것으로 나타났으며, 노화(aging)에 따른 exchangeable fraction과 carbonate fraction에서의 추출량은 큰 변화가 없었다. 대해서는 북한지역의 분포상황을 밝혔다.것을 알 수 있었으며, 크롬과 비소의 경우는 초기에 많이 용출되고, 구리의 경우는 꾸준히 용출되는 것을 알 수 있었다. 3년 된 통나무집이 8년 된 통나무집보다. 용출양이 더 컸으며, 이는 CCA성분이 초기에 많이 용출된다는 것을 의미한다. 억제 효과를 나타내었고 Hep3B에서는 부탄을 분획물 (1 mg/mL)에서 82%의 비교적 높은 성장억제효과를 나타내었다.as a "front" and "back". Thus, Germany′s private space may face a genuine public space and street, which is rare in the Korean housing. Although the layout of indoor space in the korean housing tends to be open, such an openness may be outstanding in living and dining spaces, kitchen and various accesses to rooms. In the case of Germany, such indoor spaces are usually closed to each other. Thus corridors act to separate these spaces. Such differences are analysed to be due to the different perceptions of interpersonal and socio-cultural attributes as intra-family and inter-neighbor relationships or communications. 알 수 있었다.도 질소와 인산처럼 토양지지대가 있는 경우가 낮은 함량을 유지하였다.pe from the daily life, to fantasize and daydre

• Journal of Korean Home Economics Education Association
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• v.21 no.3
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• pp.123-142
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• 2009

The purpose of this study was to examine the level of recognition, information acquisition behavior, level of knowledge, level of behaviors to decrease exposure, and education need towards endocrine disruptors of middle and high school students. The data were collected from 180 middle and high school students in Seoul, Incheon, Daejeon, Daegu, Busan and Gwangju. Frequencies, Cronbach's alpha, t tests, analysis of variance, Duncan's multiple range tests, and chi-square tests were carried out by SPSS WINDOWS Version 14.0. The results of this study were as follows. The level of concerns about endocrine disruptors was somewhat low. Many respondents obtained information about endocrine disruptors from TV/radio and school, and wanted to get the information from school and TV/radio. Both the level of knowledge and the level of behaviors to decrease exposure were not particularly high. In addition, they showed high level of education need for endocrine disruptors.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.11 no.6
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• pp.123-132
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• 2012

Gas sensors has been used very differently that depending on following purposes; Automotive (exhaust gas, fuel mixture gas, oxygen, particulates), agriculture / food industry (fresh, stored, CO2, humidity, NH3, nitrogen oxide gas, organic gas, toxic gas emitted from pesticides and insecticides), industrial / medical (chemical gas, hydrogen, oxygen and toxic gases), military (chemical weapon), environmental measurements (CO and other air pollution consisting of sulfur and nitrogen gas), residential (LNG, LPG, butane, indoor air, humidity). The types of industrial toxic substances are known about 700 species and many of these exist in gaseous form under normal conditions. he multi-gas detection sensors will be developed for casualties that detect the most important and find easy three kinds of gases in marine plant; carbon dioxide(CO2), carbon(CO), ammonia(NH3). Package block consists of gas sensing device minor ingredient, rf front end, zigbee chip. Develope interworking technology between the sensor and zigbee chip inside a package. Conduct a performance test through test jig about prototype zigbee sensor module with rf output power and unwanted emission test. This research task available early address when poisonous gas leaked from large industrial site and contribution for workers' safety at the enclosed space.