• Proceedings of the Korean Institute of Resources Recycling Conference
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• 2005.05a
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• pp.178-182
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• 2005

본 연구에서는 추출제가 함유된 추출레진$(75{\sim}150{\mu}m)$으로 채워진 저압액체크로마토그래피를 이용하여 용리온도$(20{\sim}60^{\circ}C)$와 유속$(1.41{\sim}7.04cm/min)$에 따른 Dy와 Ho의 분리특성을 조사하였다. 용리액인 HCl의 농도는 $0.25{\sim}0.5mol/L$가 적절한 것으로 판단되며, HCl $0.5mol/L$ 이상에서는 분리효과가 거의 없었다. 일정한 용리액 농도에서 유속이 느릴수록, column의 온도가 높을수록 분리도와 해상도는 개선되었으며, 유속이 느릴수록 용리액의 소모량은 감소, 분리시간은 증가하였다. 적정조건인 용리온도 $60^{\circ}C$, 유속 7.04cm/min, HCl 0.25mol/L에서 분리도는 ${\alpha}_{Dy}^{Ho}=1.36$로 가장 높았다.

• Analytical Science and Technology
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• v.20 no.5
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• pp.419-423
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• 2007

Environmental low level tritium analysis was studied using liquid scintillation counter(LSC) and electrolytic enrichment method. To obtain low level blank count, various counting vials were investigated. Among them, teflon coated PE vial had a lower blank count rate (1.86 cpm) and we obtained 2.01 Bq/L detection and tritium separation factor was above 20. LSC counting efficiency obtained $28.70{\pm}0.27%$ using the NIST tritium standard water sample.

• Analytical Science and Technology
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• v.25 no.2
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• pp.146-151
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• 2012

An analytical method was developed for the measurement of uranium isotope in ground water using the liquid scintillation counting technique. A LKB Wallac Quantulus 1220 liquid scintillation counter (LSC) equipped with pulse shape analyzer (PSA) and a solvent extraction method were used for the measurement of uranium isotope in ground water samples. The effect of solution volume on the extraction efficiency was evaluated for 100 to 1000 mL solutions using a NIST standard reference material (NIST SRM 4321C). The effect of groundwater pH on the extraction efficiency was also investigated for pH ranging from 0.5 to 10. It was found that the extraction efficiency had a strong dependence on pH showing a maximum at pH 2. In contrast, the effect of groundwater volume on the extraction efficiency was negligible in the range investigated. According to the method, the extraction efficiency of uranium isotopes was near 96% and the lower detection limit for uranium was 0.018 Bq/L with the counting time of 300 min. The result of this study was also verified by the conventional ICP-MS measurement. It is demonstrated that the suggested method is valuable to the determination of the optimum extraction and measurement conditions for uranium in ground water. The method was successfully applied to the ground water at four locations near the Daejeon province. It was found that the uranium content and the isotopic ratio of $^{234}U/^{238}U$ at the locations ranged 0.59~6.69 Bq/L and 0.72~1.40, respectively.

• Resources Recycling
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• v.22 no.6
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• pp.48-54
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• 2013

The methods to separate and remove copper in the mixed solution ((399 ppm Cu, 208 ppm Fe, 15.3 g/L Ni, 2.1 g/L Co) with nickel, cobalt and iron were investigated. With hydroxide precipitation method, copper and iron ions were completely precipitated and removed from the solution at pH 7 while some nickel and cobalt also were precipitated. 99.75% copper could be precipitated and removed as copper sulfide from the solution with adding $Na_2S$ (1.25 w/v concentration) of 2 times equivalent of Cu at pH 1. Copper was selectively absorbed on TP 207 ion exchange resin at equilibrium pH 2.0 and could be eluted from copper-loaded resin using 5% $H_2SO_4$.

• Resources Recycling
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• v.30 no.4
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• pp.64-74
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• 2021

The importance of uranium metal is growing day by day in light of its increasing global demand for fulfilling societal needs through atomic power programs. Considering the high demand for uranium, it is necessary to find innovative hydrometallurgical techniques to separate uranium from other associated elements, especially vanadium. This study deals with the separation of uranium(VI) and vanadium(V) from sulfuric acid solutions using commercial amine-based extractants diluted in kerosene. The concentrations of the sulfuric acid solutions ranged from 0.005 to 5.0 mol/L. The effect of extractant concentration ranging from 0.005 to 0.2 mol/L was studied. The temperature was maintained at 25℃ and the experiment was performed for 30 min at an aqueous: organic phase ratio of 1 (A:O = 1:1). The calculated separation factors (SFs) are presented and comparisons are made among all the experiments.

• Journal of Soil and Groundwater Environment
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• v.28 no.6
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• pp.71-89
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• 2023

A groundwater potential map (GPM) was built for the Nakdonggang River Basin based on ten variables, including hydrogeologic unit, fault-line density, depth to groundwater, distance to surface water, lineament density, slope, stream drainage density, soil drainage, land cover, and annual rainfall. To integrate the thematic layers for GPM, the criteria were first weighted using the Analytic Hierarchical Process (AHP) and then overlaid using the Technique for Ordering Preferences by Similarity to Ideal Solution (TOPSIS) model. Finally, the groundwater potential was categorized into five classes (very high (VH), high (H), moderate (M), low (L), very low (VL)) and verified by examining the specific capacity of individual wells on each class. The wells in the area categorized as VH showed the highest median specific capacity (5.2 m³/day/m), while the wells with specific capacity < 1.39 m³/day/m were distributed in the areas categorized as L or VL. The accuracy of GPM generated in the work looked acceptable, although the specific capacity data were not enough to verify GPM in the studied large watershed. To create GPMs for the determination of high-yield well locations, the resolution and reliability of thematic maps should be improved. Criterion values for groundwater potential should be established when machine learning or statistical models are used in the GPM evaluation process.

• Journal of Space Technology and Applications
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• v.4 no.2
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• pp.121-136
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• 2024

Korea Pathfinder Lunar Orbiter (KPLO), launched in August 2022, is successfully carrying out its mission. Korea's lunar lander and rover programs are expected to proceed in the future. To successfully carry out the mission after the lunar lander has landed on the surface, the performance of the equipment to be mounted should be checked in a laboratory environment similar to the Moon. Scientists and engineers of several countries, including the United States and China, use lunar soil simulant which is developed to resemble lunar soil for simulating the surface of the lunar landing site. Several lunar probe landing sites are being discussed in Korea, and lunar soil simulants such as Korea Hanyang Lunar Simulant-1 (KOHLS-1), Korea Aerospace University Mechanical Lunar Simulants (KAUMLS), and Korea Lunar Simulant-1 (KLS-1), which are similar to the characteristics of lunar mare soil, have been developed. However, those simulants are not useful if the landing site is chosen as a highland area. In this study, we introduce the process of developing KIGAM-L1, a lunar highland soil simulant similar to the chemical composition of the Apollo 16 lunar soil sample and the particle size distribution of lunar soil sample 60500-1, in case the lunar lander lands at highland area.

• Journal of Soil and Groundwater Environment
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• v.25 no.2
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• pp.16-23
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• 2020

In this work, ²²²Rn activity, major dissolved ions, and microbial community in ground- and surface waters were investigated to characterize groundwater inflow to the stream located in an urban area, Daejeon, Korea. The measured ²²²Rn activities in groundwater and stream water ranged from 136 to 231 Bq L^-1 and 0.3 to 48.8 Bq L^-1, respectively. The spatial distributions of ²²²Rn activity in the stream strongly suggested groundwater inflow to the stream. The change of geochemical composition of the stream water indicated the effect of groundwater discharge became more pronounced as the stream flows downstream. Furthermore, microbial community composition of the stream water had good similarity to that of groundwater, which is another evidence of groundwater discharge. Although groundwater inflow could not be estimated quantitatively in this study, the results can provide useful information to understand interactions between groundwater and surface water, and determine hydrological processes governing groundwater recharge and hydrogeological cycles of dissolved substances such as nutrients and trace metals.

• Resources Recycling
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• v.18 no.5
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• pp.37-43
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• 2009

The demand for rhenium has considerably increased recently owing to the large-scale consumption in industries and the price of rhenium has increased owing to the lack of supply and its availability. The dust from the roasting of molybdenite was employed to investigate the leaching behavior of rhenium and molybdenum. Leaching experiments were done by varying optimum parameters, such as reaction time, NaOH concentration and leaching temperature. The optimum leaching condition was found to be $4\;mol{\cdot}L^{-1}$ NaOH, 2 hours leaching time, $100\;g{\cdot}L^{-1}$ solid/liquid ratio, $80^{\circ}C$ temperature, and 250 rpm. At this condition, leaching percentage of rhenium and molybdenum was 86.1% and 88.6%, respectively.

• 한국지구물리탐사학회:학술대회논문집
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• 2007.12a
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• pp.53-62
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• 2007

Preliminary gas hydrate surveys were carried out From 2000 to 2004 in the East Sea. Research results showed the geophysical evidence of gas hydrate existence. In 2005, Gas Hydrate R&D Organization was established and 10 year gas hydrate development program was initiated. In the $1^{st}$ stage of the program from 2005 to 2007, 6,600 L-km 2-D seismic survey was conducted in the $1^{st}$ year 2005, and $400\;km^2$ 3D survey was conducted in the $2^{nd}$ year 2006. Acquired seismic data were processed and seismic section and 3D cube were produced. By geophysical interpretation and velocity analysis, prospective areas were mapped and candidate drilling sites were recommended. For the precise interpretation, velocity was analyzed using AVO method, and BSR signal was analyzed using deconvolution method. For the prospective area, OBS and high-resolution seismic surveys were conducted. This presentation shows the introduction and examples of the research results of the geophysical methods applied for the gas hydrate exploration in the East Sea.