• Journal of the Korea Academia-Industrial cooperation Society
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• v.12 no.7
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• pp.3117-3122
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• 2011

Skull A-P projections are the bi-product where the ESD (Entrance Surface Dose) for digital radiography is much higher than that conventional screen-film radiography. Therefore, the aim of this study was to reduce radiation doses to patients by using an added filter. This research focuses on the identification of the reduction of exposure to radiation based on the thickness of an added filter when applying the 'Skull A-P Projection' by using the 'Skull Phantom'. Also, an experiment was conducted to evaluate the qualitative decline of images through filtration. The measurement of one's exposed dose to radiation was executed by locating the 'Skull Phantom' on the position of the 'Skull AP,' while changing 16 kinds of added filters from 0.1 mmAl to 0.5 mmCu + 2.0 mmAl in terms of incident and penetrating doses. For the qualitative evaluation of images, a total number of 17 images have been acquired in the 'Skull Phantom' under the same conditions as those for the measurement of one's exposed dose. The acquired images have been evaluated by a radiological specialist. As a result, the images with a diagnostic value have been obtained by using such added filters as the compound filter of 0.2 mmCu +1.0 mmAl. The exposed dose absorbed on the 'Skull Phantom' is about 0.6 mGy. The value is only 12% of 5 mGy, the ESD value acquired on the 'Skull P-A Projection', which is recommended by the International Atomic Energy Agency (IAEA). As a result, depending on the parts of inspection, it is possible to reduce the patient's exposed dosage of radiation considerably by using an appropriate added filter.

• Journal of the Korean Society of Food Science and Nutrition
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• v.37 no.8
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• pp.1009-1017
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• 2008

For the effective use of exopeptidase from squid viscera as food processing aids, the viscera of Argentina shortfin squid (Illex argentinus) were fractionated by various methods such as acetone treatment, ammonium sulfate treatment, anion exchange chromatography, and gel filtration. The positive exopeptidase fractions were obtained from the fraction II treated by cold acetone ($30{\sim}40%$, w/w), the fraction V by ammonium sulfate ($60{\sim}70%$ saturation), the fraction II (0.2 M NaCl) by anion exchange chromatography, and the fraction I ($30{\sim}50\;kDa$) by gel filtration. The specific activities of positive fractions from viscera of I llex argentinus against substrates were higher to LeuPNA than to ArgPNA. Total activity and recovery against LeuPNA of positive fraction by gel filtration were 1,867 U and 30.69%, respectively, which were the highest among those of positive fraction. The results suggested that the gel filtration chromatography method was the most efficient method for the fractionation of exopeptidase from viscera of Illex argentinus.

• Journal of the Korean Society of Food Science and Nutrition
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• v.44 no.11
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• pp.1687-1692
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• 2015

Since the domestic grape wine industry has been stagnant, the quality of Korean wine must be improved to compete with imported wines. For improving the quality of domestic wine up to 'unfined' or 'unfiltered' wine, this study investigated the possibility of producing 'unfined' or 'unfiltered' wine and their physicochemical characteristics. Muscat Bailey A as a domestic grape was selected to make wine. Prior to refining process after alcohol fermentation, the wine samples were divided into three specimens depending on the treatment of bentonite for clarification and filter (sample A treated with both bentonite and filter, sample B treated with bentonite only, and sample C treated without bentonite and filter). The physicochemical characteristics of each specimen after one week matureness were then investigated. Sample C showed highest values in total phenol and organic acid content among others. Samples B and C showed more stability in intensity, hue, and color. Although it is hard to compare domestic wine with imported wine, it may be possible to improve the quality of domestic wine and contribute to the development of the domestic wine industry when further studies are conducted on in-depth fermentation of wine and improvement of microbiological stability.

• Membrane Journal
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• v.21 no.3
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• pp.263-269
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• 2011

In the operation of submerged membrane-coupled sequencing batch reactor, the effect of filling step on the removal efficiency and filtration performance were investigated. Two sets of operation modes, the filling step located in the beginning of aerobic step (Mode-1) and the beginning of anoxic step (Mode-2), during 89 days were conducted. There was no wide difference in the COD removal and filtration performance between two sets of operation modes. But in the removal efficiency of nutrients (total nitrogen and total phosphorous), Mode-2 was more effective than Mode-1. In the case of Mode-2, average removal efficiencies of COD, total nitrogen, and total phosphorous were 99.1, 73.3, and 77.3%, respectively.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.289-289
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• 2020

국내에서 강변여과수는 1990년대 말 이후 기술개발이 지속적으로 이루어져 왔으나, 아직까지도 방사형집수정의 적정 취수량 결정에 필요한 조사 및 설계 단계에서의 적정 조사물량에 대한 기준이 마련되어 있지 않은 실정이다. 방사형집수정 1기당 취수량 결정은 경험식에 의한 방법과 수치모델링에 의한 방법을 병행하여 이루어지고 있으나, 취수량 평가에 가장 중요한 수리전도도(k)의 오차로 인하여 설계단계에서 추정한 취수량과 시공 이후의 취수량에 차이가 존재하고 이로 인한 다양한 논쟁이 존재하고 있다. 본 연구에서는 경기도 안성천에서 시공된 방사형집수정의 사례를 토대로 조사단계에서의 적정 시추공의 갯수를 제시하고자 하였다. 수평정의 2m 간격으로 채취된 토양 및 총 8공의 시추공에서 채취된 토양 등 총 164개의 입도분석 자료를 이용하여 대표요소면적(Representative elementary area, REA)의 개념을 적용하여 적정 조사공의 갯수를 분석한 결과, 안성천 방사형집수정 규모의 경우에는 1기당 6~7개의 조사공이 필요함을 도출하였다. 본 연구에서는 경기도 안성천의 사례를 토대로 수행한 만큼 향후 낙동강 등 타 지역의 사례를 토대로 확인되고 검증된다면 강변여과수의 조사 기준으로서 활용될 수 있을 것이다.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.8
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• pp.478-488
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• 2017

Stormwater filtration is widely used for the urban runoff treatment. However, intensive maintenance and lack of information about the performance have resulted in an increased need of proper evaluation. In this study, the performance of an upflow stormwater runoff filtration system, consisting of a supporting unit and a filtration unit filled with a ceramic media, was investigated. The maximum head loss increase was about 3 cm under the suspended solid (SS) load of $30kg/m^2$ and the SS removal was more than 96%, when the filtration velocity was 20-40 m/h. The head loss and the porosity of the media can successfully be described by a power model. It was confirmed that the a significant amount of SS can effectively be removed at supporting unit, minimizing SS load to the filter media bed. Several backwashing strategies have been tested to establish the optimum condition. It was found that the stagnant water discharge is important to minimize the SS release immediately after backwashing. Also, the filter bed loaded with $400-450kg/m^2$ SS can almost completely be washed to reduce the head loss to the that of empty bed. The results in this study indicate that the upflow ceramic media filter is an excellent alternative to stormwater treatment, with high SS removal and long lifespan.

• Journal of Marine Life Science
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• v.5 no.2
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• pp.51-57
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• 2020

Disinfection and maintenance of rearing water in aquaculture is an essential element for the prevention of fish diseases. This is especially important in recirculating aquaculture systems (RAS) in which fish are reared at high density using recycled water. In this study, tilapia was reared in two different RAS (one with plasma generator - PW system, another without plasma generator - No PW system). In plasma treated group, UVT% of water was improved clearly, and the number of heterotrophic bacteria decreased significantly after 40 days. Total weight gain of tilapia in PW system was significantly higher, and other growth indicators were also relatively higher although not statistically significant. In addition, the fish in PW system had a 100% survival rate, and there were no histological differences between fish from both systems. Fish did not seem to be affected by the toxicity of ROS. In conclusion, it is expected that plasma water can effectively deactivate fish pathogens and improve the quality of rearing water.

• Proceedings of the Korea Water Resources Association Conference
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• 2016.05a
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• pp.441-444
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• 2016

본 연구에서는 유입수의 유입 방향을 달리 하였을 때 각 여재의 처리효율 차이점을 조사하고자 하였다. 실험재료는 제올라이트, 화산석, 발포 세라믹, 폴리에틸렌(Poly Ethylene) 4종의 여재이며 총 용적 31 L의 아크릴반응조에 각각의 여재를 충진하였고 각각 상향류 및 하향류의 흐름 방식을 적용하여 2차에 걸쳐 여과실험을 진행하였다. 제거효율은 유입수 대비 유출수의 농도 변화를 통하여 관찰하였고, 수질 측정은 SS, COD, T-N, T-P 네 항목으로 수질공정시험법에 의거하여 분석하였다. 실험 결과 제올라이트는 SS, COD, T-N항목에서 상향류를 적용한 여과에서 제거효율이 높은 경향을 보였다. 특히 T-N항목의 경우 상향류 조건에서 49.2%, 하향류 조건에서 34.4%의 제거효율을 나타내 흐름조건별 제거효율에 가장 큰 격차를 보였다. 화산석의 경우 SS, COD, T-N항목은 흐름방식에 따른 제거효율에 주목할 만한 차이를 드러내지 않았으나 예외적으로 T-P항목만 상향류 조건에서 24.2%, 하향류 조건에서 15.9%의 제거효율을 나타냄으로써 상향류 조건에서 8.3% 높은 제거효율을 얻었다. 발포 세라믹 여재는 하향류를 적용한 여과에서 제거효율이 우세한 경향을 보였으며 특히 COD 항목의 경우 상향류 조건에서보다 하향류 조건에서 제거효율이 7.5% 향상된 결과를 얻었다. 폴리에틸렌 여재는 전반적으로 유입 조건에 따른 경향성을 나타내지 않았으나 예외적으로 SS항목의 경우 하향류 조건에서보다 상향류 조건을 적용한 여과에서 7.9% 높은 제거효율을 얻었다.

• Journal of the Korean Society of Radiology
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• v.14 no.2
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• pp.85-95
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• 2020

The filtration characteristics of H₂O-C₆H₁₂O₆ solution at cell membrane model in renal tubule which irradiated by high energy x-ray(linac 6MV) was investigated. The cell membrane model used in this experiment was a polysulfonated copolymerized membrane of m-phenylene-diamine(MPD) and trimesoyl chloride(TMC)-hexane. They were used to two cell membrane models(CM-1, CM-2). The cell membrane model composed of 0.5 wt% TMC-hexane solution(CM-2) had higher permeate flux(Jv) and rejection coefficient(R) than composed of 0.1 wt% TMC-hexane solution(CM-1). The permeate flux(Jv) and rejection coefficient(R) of H₂O-C₆H₁₂O₆ solution in two cell membrane models(CM-1, CM-2) were increased with increase of pressure drop and effective pressure difference. In this experiment range(pressure 1.5-4 MPa, temperature 36.5 ℃), permeate flux(Jv) of H₂O solvent in irradiated membrane was found to be decreased about 20-30 times than non-irradiated membrane, permeate flux(Jv) and rejection coefficient(R) of H₂O-C₆H₁₂O₆ solution in irradiated membrane was found to be decreased about 2-13 times, about 4-6 times than non-irradiated membrane, respectively. The concentration increase of H₂O-C₆H₁₂O₆ solution at cell membrane model significantly was increased at rejection coefficient(R), was decreased at permeate flux(Jv). As the filtration of H₂O-C₆H₁₂O₆ solution in cell membrane model were abnormal, cell damages were appeared at cell.

• Journal of Korean Society of Environmental Engineers
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• v.27 no.4
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• pp.347-352
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• 2005

This research was focused on the distribution of Uranium-238 concentration in the Han River. Also, six water treatment plants in Seoul have been investigated to find out the behaviour and the removal capability of uranium. The uranium concentrations were ranged $0.02{\sim}0.54{\mu}g/L$ in the Han River. The relationship between conductivity and total dissolved solids shows that uranium concentration is positively related with conductivity and total dissolved solids. In addition, it has been founded that there was no relevance between uranium concentration and geological structure, because most of the sampling area are Banded Gneiss. The average uranium concentration in six water treatment plants was determined to $0.134\;{\mu}g/L$ in raw water, $0.050\;{\mu}g/L$ in coagulated water, $0.029\;{\mu}g/L$ in settled water, $0.020\;{\mu}g/L$ in filtered water, $0.019\;{\mu}g/L$ in finished water. After filtration in the treatment process, uranium concentration level was maintained lower than $0.029\;{\mu}g/L$. The average uranium removal efficiency compared to the raw water was 63% after coagulation, 15% after sedimentation, 8% after filtration and disinfection. The analysis shows that 78% of uranium in the raw water was removed during coagulation and sedimentation processes. However, 8% of that was removed through filtration and chlorination processes.