• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.1372-1377
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• 2009

For the remediation of the subsurface contaminated by nonaqueous phase liquids(NAPLs), it is important to characterize the NAPL zone properly. Conventional characterization methods provide data at discrete points. To overcome the weak points of conventional characterization methods, the partitioning tracer method has been developed and studied. The average saturation of NAPL($S_n$), which is the representative and continuous saturation value within contaminated site, can be calculated by comparing the transport of the partitioning tracers to that of the conservative tracer in the partitioning tracer method. In this study, the application of the partitioning tracer method in heterogeneous media was investigated. To represent the heterogeneous condition of subsurface, a two-dimensional soil box was divided into four layers and each layer contained different sized soils. Soils in the soil box were contaminated by the mixture of kerosene and diesel, and partitioning tracer tests were conducted before and after the contamination using methanol as conservative tracer and 4-methyl-2-pentanol, 2-ethyl-1-butanol, and hexanol as partitioning tracers. The response curves of partitioning tracers from contaminated soils were separated and retarded in comparison with those from non-contaminated soils. The contamination of soils by NAPLs, therefore, can be detected by partitioning tracer method considering these retardations of tracers. From our experiment condition, the average saturation of NAPLs calculated by partitioning tracer method using the methanol as conservative tracer and hexanol as partitioning tracer showed the highest accuracy, though all results were underestimated. Further studies, therefore, were needed for improving the accuracy using the partitioning tracer test in heterogeneous media.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.1049_1050
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• 2009

This paper deals with development of a low cost VI(Voltage-Currrent)-tracer for PV(Photovoltaic) system using LabVIEW and DSP(Digital Signal Processor). Although the conventional VI-tracer is a high cost equipment, it can‘t abstract the detailed parameters of solar cell. To overcome above mentioned disadvantages, in this paper, a converter type VI-tracer is developed. The DSP, which controls the buck-boost DC-DC converter, is used to implement the proposed VI-tracer algorithm. The proposed VI-tracer can abstract more detailed parameters of solar cell; A(temperature constant), Rs(series resistance), and Rsh(parallel resistance). The authors emphasize that the proposed VI-tracer can satisfy the users who need to get various parameters. A comparison between the proposed VI-tracer and the conventional VI-tracer is presented to show the effectiveness of the proposed system.

• Agricultural and Biosystems Engineering
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• 제1권1호
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• pp.16-21
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• 2000

Measurement of spray deposit is necessary for evaluation of a chemical application technology. However it is not easy and time consuming. A simple method for measuring the deposition amount of spray using a tracer and a spectrophotometer was developed. Various materials were tested to determine an adequate tracer. Food dye was selected as a tracer, because it was cheep and easily treatable. Using NIRS(Near Infrared Reflection Spectrophotometer), a regression curves between maximum absorbance of a solution and concentration of the tracer were obtained. Yellow food dye solution showed a peak of spectrum at 452 nm, and absorbance of peak showed a tendency to increase as concentration increased. Green or pink food dye were tested and judged to be good tracers. However, tracer concentration should not exceed certain limits in order to measure maximum absorption. Using spraying liquid with known tracer concentration and known amount of washing liquid, spray deposit amount on real targets on leaves could be estimated at less than 13% error level.

• Bulletin of the Korean Chemical Society
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• 제34권2호
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• pp.574-578
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• 2013

In this work, the friction and diffusion coefficients of a tracer in a mesoscopic solvent are evaluated as a function of the tracer size by a hybrid molecular dynamics simulation where solute molecules evolve by Newton's equations of motion but the solvent evolves through the multi-particle collision dynamics. The friction coefficient is shown to scale linearly with the tracer size for larger tracers in accord with predictions of hydrodynamic theories. The diffusion coefficient of tracer is found to be inversely proportional to tracer size. The behavior of Stokes-Einstein formula is validated as a function of tracer size.

• 대한환경공학회지
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• 제28권12호
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• pp.1304-1309
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• 2006

정수처리 과정에서 Cryptosporidium과 유사한 특성을 가지고 있는 C. tracer를 이용하여 공정별 제거효율을 조사하였다. PACI(Poly aluminium chloride, $Al_2O_3$(10%)) 주입량이 10 mg/L일 때 C. tracer는 97.16%로 가장 높은 제거율을 보였으며, 탁도 제거율과 SS 제거율이 높을수록 C. tracer 응집 효율이 높았다. 원수의 pH가 높을수록 C. tracer 제거율이 증가 하였으며 응집 침전 후의 유출수 탁도와 C. tracer 제거율과의 상관성이 $R^2=0.9506$로 높게 나타나 응집 침전 후의 유출수 탁도로 Cryptosporidium 제거 효율을 평가할 수 있음을 알 수 있었다. 또한 여과 실험에서는 유입 탁도에 따른 C. tracer 제거율은 $94.00{\sim}95.83%$ 범위였으며 유출수 탁도와 C. tracer 제거율과의 상관성은 $R^2=0.8704$였다. 최적 응집 조건 하에서 여과수 탁도가 양호할 경우, 예상되는 Cryptosporidium의 제거율은 응집 침전의 경우 1.55 log(97.16%), 급속모래여과의 경우 1.38 log(95.83%), 응집 침전+급속모래여과의 경우 2.31 log(99.51%)로 나타났다.

• 한국지하수토양환경학회지:지하수토양환경
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• 제15권1호
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• pp.66-72
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• 2010

The partitioning tracer method is to estimate the residual saturation of nonaqueous phase liquid (NAPL) in soils by analyzing tracer's retardation induced by the reversible partitioning of tracer with NAPL. This study is to estimate the residual diesel saturation in soils using the partitioning tracer method. Two-dimensional soil box was used to represent the 2-dimensional flows of groundwater and tracer solution in the saturated aquifer, and the soil box was filled with soil and then saturated with water. The residual diesel saturation was induced in saturated soil, and the partitioning tracer method was applied. The results from batch-partitioning experiment indicated that the diesel-water partitioning was linear with respect to tracer's concentration, and the partition coefficient of tracer between diesel and water was measured by their linearities. The groundwater flow in the saturated aquifer was simulated in the 2-dimensional soil box, and the residual diesel contamination was visually identified. The results from the partitioning tracer method with or without diesel in soils confirmed that 4-methyl-2-pentanol, 2-ethyl-1-butanol and 1-hexanol, can be used as a detecting method for diesel contamination. By the accuracies of estimations for diesel contamination using the partitioning tracer method, 2-ethyl-1- butanol showed the highest accuracy with 83%.

• 한국지구물리탐사학회:학술대회논문집
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• 한국지구물리탐사학회 2003년도 Proceedings of the international symposium on the fusion technology
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• pp.676-683
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• 2003

A laboratory experiment using artificial fracture rocks was used to understand the 3-dimensional dispersion of a tracer and the mixing process in a fractured network. In this experiment, 12cm polystyrene foam cubes with two electrodes for monitoring electric conductivity (EC) were used as artificial fractured rocks. Distilled water with 0.5mS/m was used as a tracer in water with 35mS/m and the difference of EC between the tracer and the water was monitored by a multipoint simultaneous measurement system of electrical resistance. The results showed that even if the fracture arrangement pattern was not straight in the direction of the flow, the tracer did not diffuse along individual fractures and an oval tracer plume, which was the distribution of tracer concentrations, tended to be form in the direction of the flow. The vertical cross section of the tracer distribution showed small diffusivity in the vertical direction. The calculated total tracer volume passing through each measurement point in the horizontal cross section showed while that the solute passed through measurement points near the direction of hydraulic gradient and in other directions, the passed tracer volumes were small. Using Peclet number as a criterion, it was found that the mass distribution at the fracture intersection was controlled in the stage of transition between the complete mixing model and the streamline routing model.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2001년도 총회 및 춘계학술발표회
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• pp.132-135
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• 2001

To understand and compare tracer transport in fractured and porous media. multiple tracer tests were conducted in Wonju and Uiwang sites. The target media were fractured in Wonju site and porous in Uiwang site. It was known that groundwater flow for the two hydrogeologic systems could be represented using a EPM approach. However, the tracer transport in the two aquifer systems was greatly different. In this study, we analyzed the different tracer transport behavior in the two systems, from which our understanding of the tracer dispersion was greatly enhanced. we used bromide and chloride as tracers.

• 한국농공학회지
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• 제41권4호
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• pp.57-65
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• 1999

A modified gas tracer method was used to obtain reaeration coefficient from an artificial channel and a reach of Bokha stream, Ichon city. Propane was used as the tracer gas and Rhodamine-B dye as a dispersion and dulution tracer. Concentrations of propane in water sample were measured using a gas chromatograph and concentrationsof dye using UV-Spectrophotometer. To compare measured values with predicted values,commonly used 14 equations were selected . Results of this study suggested that the modified gas tracer method is a potentially useful procedure for th edetermination of reaeration cofficients. However, estimated reaeration coefficients from predictive equations were significantly different from that of this study. Therefore, when using predictive equations, careful selection of equation with consideration for hydraulic characteristics such as flow depth and average velocity, or use of newly derived predictive equation which is adequate for questioned stream would be needed.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2004년도 총회 및 춘계학술발표회
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• pp.341-345
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• 2004

An attempt has been made in this study to evaluate an applicability of Relative Effective Porosity Model (REPM) as a method for estimating saturated hydraulic conductivity (K$_{s}$) for homogeneous coarse, medium, and fine sands. The saturated hydraulic conductivities obtained from REPM are converted into average linear velocities using Darcy's Law and compared with the results from experimental tracer tests for homogeneous coarse, medium, and fine sand layer. Two types of tracer tests analyses, analytical solution using CXTFIT and moment methods, are performed to obtain reasonable linear velocity range for each layer. For the coarse and medium sands, the converted average linear velocity from REPM is in the velocity range obtained from tracer tests. However, small difference between the results from REPM and tracer tests is found for the fine sands. These results show that REPM gives reasonable estimates of saturated hydraulic conductivity.y.