• Economic and Environmental Geology
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• v.43 no.2
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• pp.109-121
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• 2010

The bioleaching experiment under $42^{\circ}C$ was effectively carried out to leach the more valuable element ions from the pyrite in the Gangyang mine waste. Bacteria can survive at this temperature, as indigenous acidophilic bacteria were collected in the Hatchobaru acidic hot spring, in Japan. To enhance the bacterial activity, yeast extract was added to the pyrite-leaching medium. The indigenous acidophilic bacteria appeared to be rod-shaped in the growth-medium which contained elemental sulfur and yeast extract. The rod-shaped bacteria ($0.7\times2.6\;{\mu}m$, $0.6\times7\;{\mu}m$, $0.8\times5\;{\mu}m$ and $0.7\times8.4\;{\mu}m$) were attached to the pyrite surface. The colonies of the rod-shaped bacteria were selectively attached to the surroundings of a hexagonal cavity and the inner wall of the hexagonal cavity, which developed on a pyrite surface. Filament-shaped bacteria ranging from $4.92\;{\mu}m$ to $10.0\;{\mu}m$ in length were subsequently attached to the surrounding cracks and inner wall of the cracks on the pyrite surface. In the XRD analysis, the intensity of (111), (311), (222) and (320) plane on the bacteria pyrite sample relatively decreased in plane on the control pyrite sample, whereas the intensity of (200), (210) and (211) increased in these samples. The microbiological leaching content of Fe ions was found to be 3.4 times higher than that of the chemical leaching content. As for the Zn, microbiological leaching content, it was 2 times higher than the chemical leaching content. The results of XRD analysis for the bioleaching of pyrite indicated that the indigenous acidophilic bacteria are selectively attacked on the pyrite specific plane. It is expected that the more valuable element ions can be leached out from the mine waste, if the temperature is increased in future bioleaching experiments.

• Journal of Conservation Science
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• v.29 no.4
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• pp.421-435
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• 2013

The purpose of this study is to suggest environmental guidelines for the conservation of ceramics excavated from underwater. Accordingly, the conditional change of the soluble salt on surface of the excavated ceramics was examined by changing the relative humidity. Examining the relative ratio [high humidity(RH70%+RH80%)/low humidity(RH20%+ RH40%)] for 24 weeks using accumulated conductivity(${\mu}s/cm$), the result showed that the amount of ion elution increased more in high humidity than in low humidity. In particular, the ion elution increased significantly within the celadon sample. In addition, comparing the accumulated conductivity and physical characteristics of the samples in high humidity, the results indicated that the amount of the ion elution is proportioned to the increased rate of the sample's absorption capacity and porosity. Ceramics excavated from underwater has risks of the secondary physical and chemical attacks from remaining salts. Therefore, it is suggested these ceramics be stored in a storage which maintains proper temperature and low humidity conditions. Also, the collections need to be pre-classified according to the properties of the materials.

• Journal of Korea Foundry Society
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• v.43 no.5
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• pp.260-263
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• 2023

이 보고서에서는 무기 공정에서의 무기 인공 재생 모래의 특성을 중심으로 다음과 같이 정리할 수 있다. 1) ICP 발광 분광 분석을 통한 재생 모래의 Na⁺ 용출량, TP 휨강도 및 충전 밀동에는 높은 상관 관계가 확인되었다. 2) 현행 재생 방법 대비, 습식 연마 처리를 첨가함으로써 잔류 점결재가 제거되고 Na+ 용출량이 저감된 결과, 재생 모래의 TP 휨강도를 보다 개선 가능한 것이 확인되었다. 3) 재생 처리 공정 순서를 건식 연마 → 습식 연마 → 배소 처리로 함으로써, 가장 Na⁺ 용출량이 낮고, 높은 휨강도를 얻을 수 있는 것이 확인되었다. 4) 습식 연마 단계를 거치지 않고 배소 처리 온도와 처리 시간을 궁리함으로써 충분한 품질의 재생 모래를 얻을 수 있는 가능성이 시사되었다. 마지막으로, 무기 공정은 유기 공정에 비해 압도적으로 냄새가 적고 생산성이 높으며 인공 모래와의 병용을 통한 재생 처리시의 폐기물량 저감, 주조품의 고품질화 등 이점이 기대되는 공정이다.

• Journal of the Korean Wood Science and Technology
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• v.42 no.4
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• pp.460-466
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• 2014

To evaluate wood charcoal as raw material for mineral water production, dissolution of inorganic ions from charcoal to water, pH and adsorption ability of chlorine in water were investigated as main variables. More potassium ion was dissolved in water as higher temperature manufactured charcoal but other ions showed no difference with different charcoal making temperatures. Highest dissolved cation was potassium followed by calcium and sodium. Among wood species, charcoal from Quercus variabilis and Platanus occidentalis showed significantly higher potassium content in water than that of larch, red pine and white pine. Other cations had similar pattern to the potassium but their difference was not apparent as much as potassium. pH value of water treated with charcoal was higher for wood charcoals from Platanus occidentalis (pH 8.5) and Quercus variabilis (pH 8.4) which contained higher inorganic cations. In chlorine removal in water by charcoal, all wood charcoals showed greater chlorine removal than that of the control, but softwood charcoals resulted in higher removal than those of hardwoods. There was no significant difference in the dissolution of cations and pHs between particle charcoal and whole charcoal. With easy of control, whole charcoal is better for mineral water making raw material than particle charcoal does.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.16 no.2
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• pp.88-93
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• 2006

To recycle the electric arc furnace (EAF) dust as a ceramic raw materials, the leaching concentrations of heavy metals (Zn, Pb, Cr, Cd) were analysed with various pH and mixing ratios for EAF dust and EAF dust-clay mixtures. The evaporation amounts of the some heavy metals were evaluated by measuring their total concentrations in the sintered bodies of EAF dust-clay mixtures with various mixing ratio and sintering temperature. Toxicity characteristic leaching procedure (TCLP) test was conducted for evaluating the chemical stabilities of the heavy metal elements. Leaching concentrations of heavy metal ions shows minimum leaching concentration at the pH 10. Evaporation amount of heavy metals in the sintered bodies were evaluated for the mixtures of pH 10 depenidng on mixing ratio and sintering temperature. Evaporation of heavy metal components were increased with increasing the sintering temperature and contents of the EAF dust. The evaporation of the heavy metal components in EAF dust was effectively suppressed by increasing the clay content. The leaching concentrations of heavy metal components were decreased with increasing clay content and temperature.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.10
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• pp.4047-4054
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• 2010

We studied the release characteristics of the marine sediment which could facilitate sea eutrophication through some lab-scale simulation experiments. Environmental indicators such as pH, ORP(oxidation reduction potential), nitrogens, and phosphates were measured in order to calculate the corresponding release rates. $CaO_2$, an oxygen releasing compound was used to determine how it would effect on the natural process of sedimental release. COD, ammonia nitrogen, phosphorous compounds were less released under the oxic environment caused by $CaO_2$. This basic data will help developing methodology for reducing marine eutrophication which may be initiated by the sedimental release.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2003.09a
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• pp.520-523
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• 2003

강원도 지역의 대표적인 탄산용출수에 대한 수리지구화학적 연구를 통하여 심부 지열 저장지의 온도와 심부환경을 추정하였다. 탄산용출수는 공통적으로 약산성의 pH와 높은 이온함량으로 특징되지만, 화학적으로는 Na-HCO$_3$형, Ca-Na-HCO$_3$형, 그리고 Ca-HCO$_3$형으로 뚜렷이 구분된다. 심부에서 생성된 탄산용출수가 지표로 상승하는 도중에 수반된 지표수 혼합차이로 인해 이런 화학조성의 차이가 유발된 것으로 판단된다. Na-HCO$_3$형 탄산수는 화학 조성상 ‘mature water’의 특징을 보여주는 반면, 다른 두 유형의 탄산수들은 ‘immature water’에 해당하였다. Na-HCO$_3$ 형 탄산수에 대하여 실리카, Na-K 및 Na-K-Ca 지온계를 적용한 결과, 약 l15-157도의 심부저장지 온도가 산출되었으며, 이 결과는 다성분 평형계를 이용한 추정 온도 (약 140-160도)와도 잘 일치하였다. 반면, Ca-HCO$_3$ 형 탄산수들은 지표수와의 혼합 때문에 상대적으로 낮고 넓은 범위의 추정 온도 (약 60-130도)를 나타내었다. 따라서 연구지역 내 탄산용출수의 심부저장지 온도는 Na-HCO$_3$형에 대해서만 타당하게 적용될 수 있으며, 약 140-160도일 것으로 추정된다.

• Korean Journal of Food Science and Technology
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• v.24 no.6
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• pp.616-618
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• 1992

The study was attempted to isolate taurine from the oyster shucking juice known as one of the by-products of oyster processing using ion exchange column chromatography. Three hundred grams of the oyster shucking juice were loaded onto a column packed with 300 ml of the Dowex 50W $H^+$ form. And taurine-rich fractions were further purified in columns packed with 150 ml of Dowex 2 OH form and the 150 ml of Amberite IRA-410 OH form consecutively. The purity and the yield of taurine recovered from the oyster shucking juice by this method were 94.7% and 84.8%, respectively.

• The Korean Journal of Nuclear Medicine
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• v.32 no.5
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• pp.425-432
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• 1998

Purpose: For the purpose of using Re-188 as a therapeutic radionuclide, we performed the quality control of the W-188/Re-188 generator system. Materials and Methods: Several quality control tests of the Re-188 eluate from generator were carried out for about 300 days. After elution of Re-188 with normal saline (20 ml), chromatogram and gamma-ray spectrum of Re-188 eluate were obtained. The presence of aluminum which was derived from the alumina bed of the generator was detected by using aluminum ion indicator kit. Re-188 eluate was allowed to decay for several days, and then W-188 breakthrough in the Re-188 eluate was measured by detecting gamma-ray at 227 keY and 290 keV. The pH and the pyrogenicity of the eluate were checked. The Re-188 bolus was concentrated with ion exchange columns. Results: The radioactivity of Re-188 eluate from the generator was $67.4{\pm}7.0%$ of W-188 during 270 days, and it was highest at third day after previous elution. Radiochemical purity of Re-188 eluate obtained from chromatogram was higher than 99%. Gamma-ray spectrum of Re-188 eluate showed a peak at 155 keV. Aluminum ion and W-188 contamination were not detected. The PH of Re-188 eluate was 3 and the concentration yield was 85%. Conclusion: Our experiments and results on quality control tests of Re-188 eluate from W-188/Re-188 generator may be useful for setting W-188/Re-188 generator in hospitals.

• Journal of Biomedical Engineering Research
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• v.25 no.2
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• pp.157-163
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• 2004

Nitrogen ion implantation and ion plating techniques were applied for improvement of the wear resistance of metallic implant materials. In this work, the wear dissolution behaviour of a nitrogen ion implanted super stainless steel (S.S.S, 22Cr-20Ni-6Mo-0.25N) was compared with those of S.S.S, 316L SS and TiN coated 316L SS. The amounts of Cr and Ni ions worn-out from the specimens were Investigated using an electrothermal atomic absorption spectrometry. Furthermore, the Ti(Grade 2) disks were coated with TiN, ZrN and TiCN by use of low temperature arc vapor deposition and the wear resistance of the coating layers was compared with that of titanium. The chemical compositions of the nitrogen ion implanted and nitride coated layers were examined with a scanting auger electron spectroscopy. It wat observed that the metal ions released from the nitrogen ion implanted S.S.S surface were significantly reduced. From the results obtained, it was shown that the nitrogen ion implanted zone obtained with 100 KeV ion energy was easily removed within 200,000 revolutions from a wear dissolution testing under a similar load condition when applied to artificial hip joint. The remarkable improvement in wear resistance weir confirmed by the nitrides coated Ti materials and the wear properties differ greatly according to the chemical composition of the coating layers. for specimens with the same coating thickness of about 3$\mu\textrm{m}$, TiCN coated Ti showed the highest wear resistance. However, after removing the coating layers, the wear rates of all nitrides coated Ti reverted to their normal rates of below 10,000 revolutions from Ti-disk-on-disk wear testing under the same load condition. From the results obtained, it is suggested that the insufficient depth of the 100 Kel N$\^$＋/ ion implanted zone and of the nitrides coated layers of 3$\mu\textrm{m}$ are subject to restriction when used as frictional parts of load bearing implants.