• Korean Journal of Soil Science and Fertilizer
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• v.43 no.5
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• pp.596-601
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• 2010

Serious problems in reclaimed land for agriculture are high soil salinity and very poor vertical drainage. However, desalinization in these soils is very difficult. To identify the change of soil permeability by the gypsum incorporation in soils we observed elution patterns and salt distribution of the soil using soil columns packed with reclaimed saline soil with various rates of gypsum amendment. Saturated hydraulic conductivity ($K_{sat}$) of the top soil of reclaimed saline soils without gypsum incorporation was close 0 cm $hr^{-1}$ while $K_{sat}$ increased up to 0.3 cm $hr^{-1}$ with increasing amount of gypsum for 0.4% or more gypsum. Also $K_{sat}$ of the reclaimed saline soils for top soil was drastically increased to 1.0 cm $hr^{-1}$ or slightly greater after 141 hour's elution experiment. The cumulative amount of cation recovered in the effluent also increased in the order of gypsum incorporation rate 0.8% > 0.6% > 0.4 > 0.2%. Soil EC in soil columns decreased from initial 33.9 dS $m^{-1}$ to less than 0.4 dS $m^{-1}$ and exchangeable Ca 2+ increased by 32~140% according to gypsum incorporation rate.

• Analytical Science and Technology
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• v.29 no.5
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• pp.219-224
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• 2016

불산 중 극미량 음이온의 고상추출과 이온크로마토그래프를 이용한 고감도 분석법이 개발되었다. 불산 중 불소이온이 고상에 의해 제거하였고 이어서 음이온 (F⁻, CH₃COO⁻, Cl⁻, Br⁻, NO₃⁻, PO₄³⁻, SO₄²⁻)들이 이온크로마토그래프를 이용하여 연속적으로 분리하였다. 고상 추출법에 영향을 주는 각 인자들 (흡착제의 선택, 시료의 부피 및 pH, 용출 용액과 용출용액의 부피)을 결정하였으며 그 결과 흡착제로서 Oasis WAX 컬럼이 가장 우수하였고 1.0 mL의 시료부피, 용출용액으로 50 mM 초산암모늄염 5 mL가 분리능에서 가장 우수하였다. 개발한 방법에 의한 음이온 (Cl⁻, Br⁻, NO₃⁻, PO₄³⁻, SO₄²⁻)들의 방법검출한계는 25 % 불산용액 (w/w) 중에 0.04~0.30 µg/L의 범위를 보였고 정밀도는 20.0와 40.0 µg/L의 농도에서 5 % 이내를 보였다. 한 제조회사에 의한 25 % 불산 중 음이온의 4.2에서 47.5 µg/L의 범위로 모두 검출되었다. 이 방법은 시험절차가 간단하고, 재현성 및 감도가 좋아서 반도체회사에서 불산 중 음이온 불순물을 정도 관리하는데 매우 유용한 방법이 될 것으로 판단된다.

• Korean Journal of Environmental Agriculture
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• v.29 no.2
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• pp.152-158
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• 2010

Biosorption is considered to be an alternative method to replace the present adsorbent systems for the treatment of metal contaminated wastewater. In this study, by-product which was abandoned from brewing factory was used to remove metal component in aqueous solution. The experimental results showed that the range of the removal efficiency is 60~91% and adsorption equilibrium was reached in about 3 hr. FT-IR and stereo microscope has been used to observe the surface conditions and changes in functional groups by calcination. At the end of elution, the amount of nitrogen and phosphorus in water was increased 11 and 7 times compare raw sample to calcinated samples. The Langmuir isotherm adequately described the adsorption of waste materials and the maximum adsorption capacity was 28.17 mg/g for Cd. The overall results suggested that waste material might can be used for biosorption of Cd.

• Korean Journal of Food Science and Technology
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• v.29 no.4
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• pp.613-617
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• 1997

This study was performed to investigate the effects of the type of utensils (onggi, aluminum, enamel coated, stainless-steel and stone), cooking sources (deionized-water, doenjang soup and kochujang soup), and cooking time (0, 10, 20, and 30 min) on aluminum leaching. Aluminum content leached by onggi, aluminum, enamel coated, stainless-steel and stone was $0.53{\sim}2.76,\;1.17{\sim}4.20,\;0.77{\sim}3.23,\;0.53{\sim}2.03,\;0.83{\sim}2.70$ ppm in deionized-water, respectively; $4.60{\sim}7.73,\;6.45{\sim}11.50,\;5.53{\sim}9.27,\;3.50{\sim}6.70,\;5.00{\sim}9.13$ ppm in doenjang soup, respectively; $5.18{\sim}9.70,\;6.30{\sim}11.23,\;4.73{\sim}8.63,\;3.23{\sim}6.50,\;4.50{\sim}9.25$ ppm in kochujang soup, respectively. The leached aluminum content was increased with the elapse of cooking time. Aluminum utensil showed the highest leached aluminum content among different types of utensils.

• Journal of the Korean Ceramic Society
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• v.39 no.8
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• pp.728-734
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• 2002

Stabilization behavior of Cr, Cd, Cu, Pb, Fe and Zn heavy metals in the EAF dust was investigated by adding EAF dust to clay or white clay, respectively, up to 50 wt% with 10 wt% intervals and sintering at temperatures between 200 and $1200^{\circ}C$ with $200^{\circ}C$ intervals with an aid of ICP-AES followed by TCLP test to evaluate heavy metal cation exchange capacity of the clay or the white clay. The clay or the white clay had a better Cr ion exchange capacity than that of zeolite. The TCLP leaching test for the sintered specimens showed that Cr and Fe were rarely detected for all the specimens and the concentration of Cd and Zn decreased with increasing sintering temperature and decreasing EAF dust contents respectively. When the clay or the white clay were mixed with EAF dust, cation exchange may occur between the clay and the EAF dust so that the first stabilization of the mixtures containing semistabilized heavy metals may happen. Stabilization of heavy metals in the ceramic bodies was further completed probably due to the eutectic reaction caused by the sintering of semi-stabilized mixtures. It was conceivable that the white clay rather than the clay may be a better stabilizer for the EAF dust containing heavy metals.

• Journal of Soil and Groundwater Environment
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• v.9 no.4
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• pp.24-31
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• 2004

A cold mix asphalt (CMA) treatment process was proposed as a tool to recycle soils contaminated with petroleum hydrocarbons. Experimental studies were conducted to characterize performances of the CMA process in treating soils contaminated with diesel or diesel compounds. From the screening experiments, it was found that performances of five types of asphalt emulsions that contained a cationic or an anionic or a nonionic surfactant were not substantially different. In consideration of higher affinity for soils and higher sorption coefficients obtained, an emulsion containing Lauryl Dimethyl Benzyl Ammonium Chloride (LDBAC) was selected as a promising asphalt emulsion for treating diesel-contaminated soils. When the asphalt emulsion LDBAC was applied to treat three compounds that originated from diesel, the removal efficiencies obtained in the order of decreasing efficiencies were as follows: docosane > pentadecane > undecane. Leaching experiments on the specimen formulated by the emulsion LDBAC found that the selected treatment method could treat soils with diesel concentrations as high as 10,000 mg/kg. Leaching of the diesel from the specimen was controlled by diffusion for the first four days and then leaching rate diminished substantially. The latter behavior was characterized as depletion, which represents that the contaminant released amounts to more than $50\%$ of the total amount of the contaminant that can be leached. The amounts of three diesel compounds leached from the specimen in the order of decreasing amount were undecane, pentadecane, and docosane. The curing of the soil contaminated with pentadecane was relatively slow.

• Proceedings of the Korean Vacuum Society Conference
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• 2010.08a
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• pp.62-62
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• 2010

인공관절은 노인성 질환이나 자가 면역질환, 신체적인 외상 등에 의한 관절의 손상 부위를 대체하기 위해 고안된 관절의 인공대용물로써 최근 인구의 고령화와 질병, 사고의 증가에 따라 그 수요가 급격히 증가하는 추세를 보이고 있다. 인공관절의 소재로는 현재 metal-on-polymer(MOP) 소재가 가장 많이 사용되고 있는데, metal 소재로서는 Co-Cr계 합금이, polymer 소재로서는 초고분자량 폴리에틸렌 (ultra high molecular weight polyethylene) 이 주로 사용되고 있다. MOP 소재의 경우 충격흡수의 장점이 있는 반면 wear debris에 의한 골용해로 인해 관절이 느슨해지는 문제점이 발생하여 재시술의 주요 원인이 되고 있다. 또한 metal 소재로 주로 사용되고 있는 Co-Cr계 합금의 경우 인공관절의 마모, 부식 현상에 의해 Co, Cr등이 체내에 용출되어 세포독성의 문제를 일으킬 수 있다는 단점을 가지고 있다. 본 연구에서는 고체원소 이온주입 기술을 이용하여 316L stainless steel 기판에 niobium을 이온 주입 한 후 niobium nitride (NbN) 박막을 증착하여 counterpart 소재인 초고분자량 폴리에틸렌(UHMWPE) 의 마모를 줄이는 실험을 진행하였다. Pin-on-disk tribometer를 통해 마모 테스트를 진행하여 NbN 박막의 내마모특성을 평가하였으며, 박막의 결정구조 및 화학적 특성을 평가하기 위해 XRD, AES 분석을 수행하였다. 또한 박막의 경도와 표면조도를 측정하기 위해 micro hardness tester, AFM을 이용하였다.

• Economic and Environmental Geology
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• v.54 no.2
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• pp.259-269
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• 2021

The effects of the physicochemical properties of soil such as soil pH, cation exchange capacity, and organic matter content on single extraction of Cd, Cr, Cu, Ni, Pb, and Zn using CaCl2, HOAc, HNO3, and DTPA were statistically investigated for 69 agricultural soils in Korea. Correlation analysis and multiple regression analysis were applied for soil samples which were grouped on the basis of average values of the physicochemical properties of the soil. Diluted HNO3 extracted higher concentrations of Cr, Cu, Ni, and Pb when compared with the other extractants, however, similar amounts of Cd and Zn were extracted by HOAc with HNO3. The results of correlation analysis indicated that DTPA extraction showed a high correlation with other single and pseudo-total extraction methods, and the physicochemical properties of soil influenced the concentrations of heavy metals leached by the single extraction methods. In the case of Zn, high correlations between pseudo-total and the studied single extraction methods were observed. As a result of regression analysis, it was found that the physicochemical properties of the soil could explain up to 74% of variances of the single extraction results. These results indicate that the physicochemical properties of the soil can have a direct influence on the concentrations of heavy metals extracted by the single extraction methods.

• The korean journal of orthodontics
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• v.25 no.2 s.49
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• pp.187-200
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• 1995

To estimate the characteristics of Korean Ni-Ti alloy orthodontic wire, this study investigated compositions, tensile properties, bending properties, heat treatment effects, and ion releasing degrees, and compared these characteristics to those of the imported Ni-Ti alloy wire. The results obtained are as follows ; 1. Ti and -Ni elements in ORTHOLLOY were in a range showing superelasticity, and there was a little difference in the Ni and Ti contents of ORTHOLLOY as compared with those of SENTALLOY. 2. The results of the tensile test concerning ORTHOLLOY exhibited a superelastic effect, indicating an area of a definite amount of stress in spite of the changes in the range from $2\%\;to\;8\%$ in the strain rate. 3. ORTHOLLOY presented higher load values than SENTALLOY in the same deflection values when the wire was tested in three-point bending. A load range displaying a superelastic effect was 80-l00g, 140-l80g, and 130-200g respectively, in wire diameters of 0.014', 0.016', and 0.018' 4. By heat treatments at $400^{\circ}C$ and at $500^{\circ}C$, a load range showing the effect of superelasticitly was lessened by the duration of the heat treatment time. The superelastic effect was destroyed as a result of the 10 minutes heat treatment at $600^{\circ}C$. 5. The quantity of the Ni ion released from ORTHOLLOY, tended to be greater than the amount of released Ni ion in SENTALLOY. The Co ion released was very little(<0.01ppm) in SENTALLOY and ORTHOLLOY irrespective of the lapse of time. Released Ni ions on the 1st day were at the maximum, and the releasing rate showed plateaus after three days. 6. The surface morphology of SENTALLOY was relatively regular irrespective of the lapse of rime, and the corrosion tendency was not observed. However, the surface morphology of ORTHOLLOY was rather irregular and shelved fitting corrosion after immersion.

• The Journal of Korean Academy of Prosthodontics
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• v.58 no.4
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• pp.275-281
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• 2020

Purpose: Development of a latent antimicrobial soft liner is strongly needed to overcome a possible inflammation related with its dimensional degrade or surface roughness. Modified tissue conditioner (TC) containing chitosan-doped silver nanoparticles (ChSN) complexes were synthesized and assessed for their characterizations. Materials and methods: ChSN were preliminarily synthesized from silver nitrate (AgNO₃), sodium borohydride (NaBH₄) as a reducing agent and chitosan biopolymer as a capping agent. Ultraviolet-visible and Fourier transform infrared spectroscopy were conducted to confirm the stable reduction of nanoparticles with chitosan. Modified TC blended with ChSN by 0 (control), 1.0, 3.0 and 5.0 % mass fraction were mechanically tested by ultimate tensile strength (UTS), silver ion elution and color stability (n=7). Results: At 24 hour and 7 day storage periods, UTS values were not significant (P>.05) as compared with pristine TC (control) and silver ion was detected with the dose-dependent values of ChSN incorporated. Color stability of TC were influenced by ChSN add, with the higher doses, the significantly greater color changes (P<.05). Conclusion: A stable synthesized ChSN was acquired and modified TC loading ChSN was characterized as silver ion releasing without detrimental physical property. For its clinical application, antimicrobial test, color control and multifactor investigations are still required.