• Bulletin of the Korean Chemical Society
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• 제22권6호
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• pp.616-622
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• 2001

Split-flow thin (SPLITT) cell Fractionation(SF) is a technique that allows separation of particulates and macromolecules into two fractions. A gravitational SF(GSF) system is constructed and tested for its applicability for separation of dust and ground water particulates. When tested with polystyrene latex particles, experimental data were in good agreements with theory. The 9.8 and 21.4㎛ polystyrene particles were successuflly separated in a continuous mode, where the mixture is continuously fed into the GSF channel allowing separation in a large sacle. The GSF system is successfully applied to continuous separation of dust and ground water particels based on the sedimentation coefficient, which is closely related to the particle size. The separations were confirmed by microscopy and energy-dispersive X-ray (EDX) analysos.

• Nuclear Engineering and Technology
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• 제54권11호
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• pp.4236-4243
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• 2022

An industrial nuclear technique based on the use of an X-ray profiler was implemented to estimate the densities or concentrations of sediments present in an Atlantic maritime zone in the areas subjected to dredging under the governance of the Panama Canal Authority (ACP). The sediment profiles show in most areas there is a concentration of between 1.00-1.15 g/cm³ except for one area in particular, the density starts at 1.20 g/cm³ and even reaches values greater than 1.50 g/cm³; therefore, an already consolidated sediment is present, which, depending on the depth found. Values of 1.265 g/cm³, 1.297 g/cm³, 1.185 g/cm³ obtained by ACP previous studies are within the range of 1.20-1.30 g/cm³ measured with the nucleonic gauge. However, it should be noted that during the tests with the X ray profiler, sediment densities values greater than the aforementioned limit were also obtained that varying according at depths close to 12 m and 18 m with values reached up to 1.513 g/cm³ and 1.60 g/cm³, respectively. This demonstrates that sediment accumulation depends on depth. This nucleonic gauge is feasible technique for the study of the sedimentation phenomenon in channel basins and even in other projects nationwide.

• 한국관개배수논문집
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• 제21권1호
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• pp.118-126
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• 2014

In this study, the use of the spur of riverbank technique is being investigated. The spur of the riverbank typically reduces the velocity of flow and protects the embankments by increasing friction along the water and the banks. This also has an effect in the rise of water level upstream. It is also used for the rectification of riverside line and restoration of the waterway through sedimentation near the spur of the riverbank. In this study, physical-scaled experiments are conducted to investigate the process of creating a mild meandering channel using the spur of the riverbank with varying water flows and sedimentation functions. The hydraulics observations are taken with respect to the varying heights and length of the riverbank's spurs and the distance between each spur for the formation of the mild meandering channel. It is observed that for 1.06 times of the meander length, it requires 2 times of the interval with each spur of river width. Similarly, 1.25L times of the meander length, it requires 0.5 times of the interval with each spur of river width. The sand accumulation is induced by the spur of riverbank when the spur of riverbank's heights are more than 40% of water depth and the length of the spur of riverbank needs under than 20% of river width for avoid exaggerated sand accumulation in the center of channel.

• 한국지반공학회지:지반
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• 제3권3호
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• pp.49-62
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• 1987

우리나라 서해안 반월지역에 산재한 해성토의 침강특성에 대한실험적 연구를 실시하였다. 준설토와 같이 토장자를 다량으로 함유하고 있는 흙의 침강은 자유침강이론만으로 설명할 수 없 다. 따라서 본 연구에서는 Kynch, McRoberts and Nixon의 간섭침강이론을 도입하여 반월해함토의 침강특성을 실험을 통하여 파악하였다. 그 결과에 의하면 초기함수비 1000%에서 간섭침강발생함을 알았다. 또한 침강계면의 하강과 묵 적고의 관계를 시간의 함수로 실험에 의해 그 관계를 확인하였다.

• 농촌의학ㆍ지역보건
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• 제15권2호
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• pp.107-111
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• 1990

A survey was undertaken to evaluate the present status of intestinal infection in army soldiers. Stool specimen of 417 soldiers fixed by SAF solution were collected from a camp located in area of Nakdong river during the period from August to October of 1990. And these stool samples were examined by formalin-ether sedimentation technique once for helminths and protozoan cysts stained with Lugol's iodine solution. The results obtained in this survey were summarized as follows : l) The overall positive rate of intestinal parasite was 18.0%. 2) The egg positive rate of intestinal helminth was 15.1%, : and 11.5% for Clonorchis sinensis. 5.0% for Metagonimus vokogawai, 1.2% for Ascaris lumbricoides 1.7% for Trichiuris trichiura. 0.2% for Taenia sp. 3) The cyst positive rate of intestinal protozoa was 4.1% ; and 1.4% for Entamoeba coli, 1.9% for Giardia lamblia 0.7% for Entamoeba histolytica, 0.5% for Endolimax nana. 4) Most of samples were positive(85.3%) by single species. 10.7% by two species, 2.7% by three species and 1.3% by four species. 5) Infection rate of intestinal parasites among army soldiers decreased distinctly compared with previous data but it is revealed that the infection rate of Clonorchis sinensis among army soldiers in area of Nakdong river is still high in comparison with ever-reported data. 6) SAF fixatives used in this field survey during summertime was useful to conserve protozoan cyst and helminths ova. Also we could examine stool samples directly by formalin-ether sedimentation technique.

• 환경정책연구
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• 제9권2호
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• pp.41-55
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• 2010

댐은 사회전반에 걸쳐 많은 편익을 제공하고 있다. 이를 위해서는 일정수준 이상의 저수용량 확보가 필수적이다. 그러나 상류의 토사 유입으로 인하여 댐의 저수용량은 줄어들고 있는 실정이다. 전 세계적으로 5조 톤의 토사가 매년 댐 뒤에 쌓이는 실정이다. 강이 여러 지역에 걸쳐 흐르는 경우 상류의 농업에서 발생하는 토사는 장시간에 걸쳐서 지속적으로 발생하기 때문에 상류 농업종사자들은 관리를 소홀히 하는 경향이 있다. 특히 토사는 댐의 저수용량을 지속적으로 줄여 궁극적으로는 댐의 경제적 가치를 소멸시키는 효과가 있다. 따라서 상류 지역의 토사저감 노력과 함께 댐의 저수용량 확보가 급선무이다. 실증분석으로 나일강 상류의 수단 농업지역과 하류의 이집트 Aswan High Dam을 분석하였다. 실증분석 결과 상류 농업부문의 토사저감 노력과 댐의 토사제거 방안이 사회전체의 경제적 편익을 극대화하는 것으로 나타났다. 동태적 최적제어이론을 이용한 유역토사관리 모형에서 댐의 경제적 편익을 포함한 사회전체의 편익은 크게는 약 1,510억 달러로 추산되었다.

• 한국지반공학회지:지반
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• 제10권1호
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• pp.71-82
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• 1994

준설매립지의 현장계측결과에 의하면 실제의 자중압밀 침하량은 실내시험결과를 근거로한 설계치보다 작게 평가되고 있다. 이러한 원인중의 하나를 본 연구에서는 준설재료의 퇴적시 압축성의 저감에 의한 것이며 더욱이 이러한 시간효과는 펌프준설매립지와 같이 저응력범위의 압밀특성에서는 고려되고 있지 않는 실정이다. 본 논문에서는 준설점성토의 압축성에 대한 시간효과를 파악하기 위하여 퇴적된 공시체에 침투력을 작용시켜 일련의 침투압밀시험을 수행하였다. 또한 본 연구에서와 같이 초기함수비가 큰 경우에 발생하는 압밀해의 불안정성을 극복하기 위하여 예측자-수정자법을 이용한 유한차분에 석기법을 제시하였고 실험결과와 비교하여 좋은 결과를 얻었다. 최종적으로 준설점성토의 압축성은 자중압밀시간에 의존되고 있음이 관찰되었다.

• 한국지능시스템학회논문지
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• 제24권2호
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• pp.147-154
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• 2014

본 논문에서는 발암물질 저감을 위하여 정수장 염소투입공정 중 전염소 주입에 따른 침전지의 염소 증발량이 주야간, 계절별 현격한 차이가 발생함에 따라 시간대별/계절별/날씨별 유입목표 잔류염소를 변경하고자 운영자의 경험에 기반한 퍼지 모델링 기법을 도입하였다. 퍼지에 의해 설정된 목표 잔류염소농도를 유지하기 위하여 침전지 유입부에 잔류염소 계측기를 추가 설치하여 피드백 Loop 시간을 최소화하였고 지연시간이 긴 시스템에 적용되는 이중 피드백 제어시스템인 캐스케이드 제어를 병행 실시하였다. 이를 통해 소독공정의 고유특성인 시간지연에 대한 선제적 대응 및 침전지 잔류염소농도 변화폭을 7.3배가량 안정화를 시키고 염소소모량을 저감하여 안정적이고 경제적인 물 공급이 가능하도록 하였다.

• 상하수도학회지
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• 제20권6호
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• pp.911-918
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• 2006

This study was conducted to evaluate the effect of the launder type on settling performance and hydrodynamic behavior within the two certain full-scale sedimentation basins (each flow rate/one basin; $10,000m^3/d$); one is the transverse typed launder(existing basin) and the other is building the finger type launder in combination with the longitudinal baffle. Comparative experimental investigations have been carried out through residual turbidity and particle concentration measurements in each effluent from two basins with the transverse and the finger type launders, respectively. From the experimental results, we could observe that turbidity removal rate in the finger type launder basin (modified basin) is about 30% higher than that in the transverse type launder basin (existing basin). Also, from the measurement of total particle concentration in each effluent, the removal efficiency was improved about 27% within modified basin compared to the existing basin. In order to explain the comparative experimental results and investigate the hydridynamic behavior within each basin in more detail, we conducted computational fluid dynamics (CFD) simulation and verified simulation results with acoustic Doppler velocimetry (ADV) technique. From the CFD simulation, it was investigated that extreme upward flow occurs underneath of the transverse launder. On the other hand, in the case of modified basin, the upward flow, which occurred in the beneath of launder, was much less than that in the existing basins.

• Parasites, Hosts and Diseases
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• 제38권4호
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• pp.275-277
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• 2000

The status of intestinal parasite infections was investigated in two rural villages (Chitrasar, Jerona) in Chitwan District, Nepal in 1999. Stool examination was performed with a total of 300 specimens from schoolchildren by formalin-ether sedinentation technique. The prevalence rate of intestinal parasite infections in the surveyed areas was 44.0%. The prevalence rate in Jerona was slightly higher than that in Chitrasar. The prevalence rate of intestinal parasite infections in female was slighly higher than that in male without statistically significant difference. Entamoeba coli was the most commonly found protozoan parasite (21.0%) followed by Giardia lamblia (13.7%) and others (5.3%). Hookworm was the most prevalent intestinal helminth (13.0%) followed by Trichuris trichiura (3.0%) and others (5.0%). forty-three specimens (14.3%) Showed mixed infections. It is necessary to implement large-scale treatment with anthelminthics, health education and sanitary improvement for intestinal parasite control in the surveyed areas.