• 대한설비공학회:학술대회논문집
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• 대한설비공학회 2006년도 하계학술발표대회 논문집
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• pp.393-398
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• 2006

This study is undertaken to evaluate the characteristics of cross contamination around exterior air-vents. A CFD analysis has been performed to calculate the cross contamination index for five exterior air-vents sizes according to the outdoor air velocity and separation distance of it. From the result of the numerical method, As the outdoor air velocity is increased, the cross contamination index is increased. on the contrary, as the separation distance of exterior air-vents is increased, the cross contamination index is decreased, additionally the cross contamination is affected by the aspect ratio of the size of exterior Air-vents.

• 환경위생공학
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• 제8권2호
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• pp.99-108
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• 1993

It is well known that we should take 2L of drinking water per day to maintain our health. The drinking water quality is becoming worse owing to sewage discharge and industrial wastewater. Surface water is polluted by various kinds of contaminants and ground water were known as clean and unpolluted water, but through recent many reports the ground waters are also contaminated by waste disposal and intrusion of organic and bacterial movement. This research was undertaken to make a water index of water contamination by referringcations cations and anions. NH$_{4}$, Fe, Mn, and Pb are chosen as cations and $NO_3$, Cl, and $SO_4$ ions are chosen as anions to make a index, and the following water index was made as the contamination index. (Fe+Mn+Pb)/0.7+$(NH_4+NO_3+Cl+SO_4)$/10.5<6.0 By using ton Chromatography the cations and anions are rapidly analyzed and plotting the analyzed data to the equation, we can easily get the degree of contaminations by avoiding analysis of over 37 water parameters in several days. Of course this index of water contamination is not perfect and detail one, but in case of emergent case or to know the overall trends of contamination, it is convenient to use this index. Among the tested 5 kinds of samples the ground water showed contamination index of 6.87. Authors used the already published healthy index and tasty index and differentiated their degrees in detail.

• Ocean Science Journal
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• 제40권1호
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• pp.1-10
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• 2005

Variations in species diversity and abundance of polychaete taxocenes that occurred in 1980-1989 under different contamination levels of bottom sediments were studied in three areas of Peter the Great Bay. The most polluted area was shown to be the Golden Horn Inlet where contaminant contents in the bottom sediments exceed the threshold values of negative biota alterations. Amursky Bay is characterized by a moderate level of contamination, while Ussuriysky Bay has the lowest level of contamination. Pollutant contents vary considerably within the same areas and their separate patches are polluted differently. An integral index characterizing the contamination of bottom sediments is proposed. This index is an average grade of the rank value of contaminant contents in sediments. The index was used to compare the contamination level and data on polychaete species diversity and abundance. The highest species diversity of polychaetes is found in the least affected zones. Monotonous decrease of the species number, as well as decrease in the indices of diversity and evenness, is correlated with pollution level increases. Significant growth of the average polychaete biomass and polychaete density is observed in the case of an increase of contamination from low to moderate levels. Conversely, the biomass and abundance of polychaetes decline following an increase in contamination.

• 해양환경안전학회지
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• 제24권7호
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• pp.907-915
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• 2018

다양한 산업분야에서 중금속의 사용이 증가할수록, 중금속으로 인한 환경오염과 생물학적 위해성에 대한 우려의 목소리가 커지고 있다. 통계 지수는 배경농도 값과의 비교를 통해 중금속 오염농도를 정규화 시킴으로써 토양 오염의 정도를 수치화하고, 단계 별로 오염 정도를 판단 할 수 있어 많이 사용된다. 본 연구에서는 농축인자(Enrichment factor, EF), 축적 계수(accumulation index), 잠재적 생물학적 위험 지표(potential ecological risk index)등을 이용하여 중공업 근처 토양 내 중금속 오염가능성을 평가하였다. 연구결과, 중금속의 오염 정도는 정부 가이드라인에 비하여 낮은 수준이었으나, 특정 위치에서 아연, 구리, 납 등의 중금속 오염이 관찰 되었다. 농축인자, 축적계수, 생물학적 위험 지표를 통해 일부 토양 내 중금속 오염이 우려할 수준이며, 주변에 존재하는 인위적 오염원에 의한 오염가능성이 있음을 확인하였다. 연구대상지의 추가 시료채취 및 추정되는 오염원의 시료 확보 후, 동위원소 분석 및 x-ray 기반 분석을 통해 오염원 추적연구가 필요할 것으로 판단된다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제26권4호
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• pp.8-19
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• 2021

In this study, the evaluation standard for nitrate nitrogen contamination degree (WELCUP) was established using six factors that influence the groundwater quality in Jeju Island. To do this, weightings, ranges, and ratings were assigned for each factor and the relative possibility of nitrate nitrogen contamination degree was evaluated using WELCUP index for each well. As a result of calculating the WELCUP index using groundwater quality data of 5,112 wells in Jeju Island for 27 years (1993-2019), all 61 wells with the WELCUP index value higher than 100 are distributed in Daejung and Hangyung watershed with relatively large area of farmland in Jeju Island. In particular, as the ratio of private wells is more than 64%, it is necessary that systematic management is needed for private wells in terms of nitrate nitrogen contamination. Consequently, based on the results of applying the WELCUP evaluation standard, it is necessary to select the prioritization of nitrate nitrogen contamination pathways project for groundwater wells in Jeju Island.

• 한국토양환경학회지
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• 제2권3호
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• pp.31-38
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• 1997

산성폐수에 함유된 오염물질의 물리적 화학적 특성이 배우 복잡하기 때문에 산성폐수에 의해 오염된 지표수나 지하수등의 오염정도를 지역적, 시간적 변화에 따라 비교하는 일은 쉽지가 않다. 본 논문에서는 산성폐수에 의해 오염된 지표수나 지하수의 오염도를 정량적으로 평가할 수 있는 수학적 지표를 제시하였으며, 오염지표를 이용하여 국내 폐탄광의 갱내 유출수에 대한 오염도를 검토하였다. 사용된 오염지표(Acid Mine Drainage Index)는 수질의 오염정도를 가장 잘 나타낼수 있는 7개의 변수 즉, pH값, 황산염(Sulfate), 철, 망간, 알루미늄, 구리 및 아연 함량을 이용하여 계산하였다. 사용된 변수는 오염도에 미치는 상대적인 중요도를 감안하여 가중치를 사용하였으며 , pH값 및 황산염함량에 가장 높은 가중치를 부여하였다. 국내 폐광산에서 유출되는 산성폐수의 오염도 평가결과 경북 문경에 소재한 석봉탄광이 조사탄광중 상대적으로 오염도가 높았으며, 지역적으로 영동지역에 위치한 폐탄광의 갱내 유출수가 영서, 중부, 서부 및 남부에 위치한 폐탄광에 비해 오염도가 높게 나타났다.

• KSTLE International Journal
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• 제8권1호
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• pp.1-6
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• 2007

Chromatic device was developed using light emitting diodes, optic fibers and photodiodes. Chromatic ratio and total contamination parameters based on transmitted light intensity in Red, Green, and Blue wavelengths were used for oil chemical and particulate contamination assessment. Chromatic ratio criterion was found independent of the particulate contamination of oil; but depended on chemical degradation, being more sensitive for synthetic than mineral hydraulic oil. Total contamination index of the sensor depended on both the chemical degradation and particulate contamination of the oil; being most sensitive in blue wavelength, and least in the red. Test results for synthetic hydraulic oils monitored corroborated with results of other tests such as viscosity, total acid number, elemental optical emission spectroscopy, particulate counts and UV-VIS photospectrometry. Chromatic ratio showed a clearer indication of oil degradation, compared to key monitoring parameters such as total acid number, viscosity and particle counts. The results showed that these parameters are effective criteria for the condition monitoring of synthetic hydraulic oils.

• 한국환경농학회지
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• 제41권1호
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• pp.9-15
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• 2022

BACKGROUND: Heavy metals discharged from various sources contaminate the soil and water and the residuals can persistently be accumulated. In this study, the concentration of soil heavy metals was assessed over the whole regions of Korea based on the contamination factor and the geoaccumulation index. METHODS AND RESULTS: The data of averaged concentrations of heavy metals and fluorine were collected from the Korean Statistical Information Service (KOSIS) and the research papers published. In order to classify the levels of heavy metal concentration, the contamination index, including the contamination factor and the geoaccumulation index, based on the relative ratio of the actual concentration of heavy metals in the soil to the background concentration was calculated. In addition, the distribution of heavy metals in soils was visualized by using the geographic information system (GIS). As a result, the Cd contamination in the soils was the most concerned. CONCLUSION(S): This study very roughly indicated the outline of heavy metal concentration over the whole regions of Korea. The change in heavy metals' concentration over the time should further be monitored and the larger data of heavy metal contamination are needed for better understanding in the future.

• 한국물환경학회지
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• 제37권4호
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• pp.296-305
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• 2021

This work investigated heavy metal pollution in surface sediments of rivers in Busan, Korea. Surface sediments were analyzed in order to conduct contamination assessment of organic matter, nutrients, and heavy metal concentrations. Contamination assessment of heavy metals was conducted using geoaccumulation index (I_geo), pollution load index (PLI), and potential ecological risk index (RI). Accumulation of organic matter and nutrients were affected by water discharged from sewage treatment plant. The concentrations of organic matter and nutrients were found to be greater in points which were close to the sewage treatment plant more than points furthest. The concentrations of Pb, Zn, Cu, Cd, Hg, As, Cr, and Ni were found to be greater in surface sediment more than in the background. The mean concentrations of heavy metals were in the order of Zn (323.5 mg/kg) > Cu (70.5 mg/kg) > Pb (39.8 mg/kg) > Cr (33.4 mg/kg) > Ni (13.5 mg/kg) > As (9.4 mg/kg) > Cd (0.84 mg/kg) > Hg (0.092 mg/kg). The result of geoaccumulation indices indicated that Hg > Cr > Cu > Ni > Zn > As > Pb > Cd were found in order of severe contamination by heavy metals. From PLI and RI analysis, it was evident that the Suyeonggang 2 was the most contaminated river.

• Geomechanics and Engineering
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• 제14권6호
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• pp.563-570
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• 2018

Ballast layer has an important role in vertical stiffness and stability of railway track. In most of the Middle East countries and some of the Asian ones, significant parts of railway lines pass through desert areas where the track (particularly ballast layer) is contaminated with sands. Despite considerable number of derailments reported in the sand contaminated tracks, there is a lack of sufficient studies on the influences of sand contamination on the ballast vertical stiffness as the main indicator of track stability. Addressing this limitation, the effects of sand contamination on the mechanical behavior of ballast were experimentally investigated. For this purpose, laboratory tests (plate load test) on ballast samples with different levels of sand contamination were carried out. The results obtained were analyzed leading to derive mathematical expressions for the strain modulus ($E_V$) as a function of the ballast level of contamination. The $E_V$ was used as an index for evaluation of the load-deformation characteristics and bearing capacity of track substructure. The critical limit of sand contamination, after which the $E_V$ of the ballast reduces drastically, was obtained. It was shown that the obtained research results improve the current track maintenance approach by providing key guides for the optimization of ballast maintenance planning (the timing of ballast cleaning or renewal).