• Journal of Korean Society of Environmental Engineers
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• v.30 no.3
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• pp.345-351
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• 2008

Fe-impregnated activated carbon(Fe-AC) was prepared by Fe(III) loading on activated carbon(AC) in various preparation pH. In order to evaluate the stability of Fe-AC, dissolution of iron from Fe-AC in acidic conditions was measured. In addition, batch experiments were conducted to monitor the removal efficiency of copper by Fe-AC. Results of stability test for Fe-AC showed that the amount of extracted iron increased with contact time but decreased with increasing solution pH. The dissolved amount of iron gradually increased at solution pH 2 and finally 13% of the total iron loaded on activated carbon was extracted after 12 hr. However dissolution of iron was negligible over solution pH 3. Removal of Cu(II) by Fe-AC was greatly affected by solution pH and was decreased as solution pH increased as well as initial Cu(II) concentration decreased. Surface complexation modeling was performed by considering inner-sphere complexation reaction and using the diffuse layer model with MINTEQA2 program.

• Proceedings of the Korean Reliability Society Conference
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• 2006.05a
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• pp.239-246
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• 2006

프레스다이용 코일스프링은 자동차 및 전자제품의 외형생산에 필요한 금형 내에 장착되는 금형용 스프링으로서 녹아웃 및 스트리퍼 등에 사용되고 있다. 프레스다이용 코일스프링이 사용 중 파손 시에는 고가인 금형의 손상 및 생산성에 영향을 미칠 수도 있기 때문에 사용 환경에서의 신뢰성확보가 요구되어지고 있다. 특히 중(重)하중 및 극중(極重)하중용 스프링은 과거 현장에서 파손사례가 자주 발생함으로 인해 외산을 선호하는 경향이 있는 형편이다. 이에 국산 스프링의 신뢰성검증 및 확보를 위해 신뢰성기반구축사업을 통해 신뢰성평가기준(RS D 0014)가 제정되었으며, 이 평가기준에 의거하여 국내 업체의 제품에 대해 신뢰성평가를 실시하였다. 프레스다이용 코일스프링의 파손원인은 주로 반복하중에 의한 피로파손과 일정한 변위의 변형으로 발생하는 코일스프링 자유높이의 축소로 크게 구분되어질 수 있다. 시험결과 주 파손양상은 피로에 의한 균열발생이었으며, 코일 끝단부와 끝단부 직하부의 코일과의 마찰에 의한 균열발생이 주원인이었다. 즉, 코일의 끝단면과 직하면 코일이 연속적으로 부딪침으로써 발생한 변형 및 마모에 의해 표면균열이 발생하고, 표면균열에서 반복적인 부하하중이 가해짐으로써 피로균열 진전을 통해 점차적으로 파손이 진행되어졌음을 알 수 있었다. 본 발표에서는 기준에 의거하여 로하중용 프레스 다이용 코일스프링을 평가한 신뢰성평가시험 결과에 대해 보고하고, 파단면 관찰과 외산제품과의 미세조직 및 조성 등의 비교분석결과 등을 기초로 파손원인을 분석한 결과에 대해 보고하고자 한다.제고할 수 있을 것으로 기대한다.X>$CdCl^+,\;CdSO_4$ 등이 형성되었다. 수은의 경우는 해수 및 증류수를 용출용매로 이용한 모든 경우에서 납, 구리, 카드뮴과는 달리 대부분 침전하였다. 더욱이 해수에 존재하는 고농도 염소($Cl^-$)와의 수착으로 인해 finite solid인 calomel($Hg_2Cl_2$)이 형성되어 대부분 침전(SI=0)되기 때문에 납, 구리, 카드뮴 보다 더 낮은 환경이동성을 갖을 것으로 사료된다. 상기 실험결과 용출용매로 증류수와 해수를 이용했을 때, 제강 슬래그에서 용출되는 납, 구리, 카드뮴, 수은의 용출 경향의 차이를 확인할 수 있었고 이에 따라서, 납, 구리, 카드뮴의 용출 유해성은 낮기 때문에 해양구조물로의 제강슬래그 유효이용은 적합할 것으로 판단되었다.im80%$로 계산되었다. 열형광선량계로 측정된 방사선량은 각각 1.8, 1.2, 0.8, 1.2, 0.8 (70 cm 거리) cGy로 측정되었으며, 환자의 복부 표면에서의 서베이메터를 이용한 측정량은 10.9 mR/h였다. 차폐구조물의 사용 시 전체 치료 동안에 태아선량은 약 1 cGy 정도로 평가되었다. 결론 : AAPM Report No.50의 자료에 따르면, 임산부의 방사선 치료 시 태아의 방사선 피폭선량은 5 cGy 이하일 경우에 방사선 피폭에 따른 태아의 위험이 거의 없는 것으로 제시되고 있다. 본원에서 차폐 구조물을 설치하였을 경우에 측정된 태아선량은 약 1 cGy로 측정되었고, 고안된 차폐구조물

• Korean Journal of Soil Science and Fertilizer
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• v.19 no.3
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• pp.217-221
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• 1986

A column test was conducted to find out the effect of application of slaked lime, calcium sulfate, calcium superphosphate, and phosphoric acid on the solubility of lead in soil. The soil was adjusted to 310.8 ppm concentration of Pb and applied with amounts of calcium equivalent to 600, 1000, 2000 ppm as slaked lime; sulfate 144, 288, 432 ppm as calcium sulfate; phosphate 95, 190, 285 ppm as calcium superphosphate and phosphoric acid, respectively. The results obtained are as follows: 1. The increasing application of improvement agents reduced the amounts of water soluble Pb in soil. Phosphoric acid was the most effect among to the treatments. 2. The slaked lime treatment has the highest pH of soil and the lowest at the phosphoric acid one. The soil Eh has a reverse tendency the soil pH. 3. Water soluble Ca, $PO_4$ and $SO_4$ contents increased with increasing application amounts of improvement agents in soil. 4. $1N-NH_4$ OAC soluble Pb content in soil was a decreasing tendency in the order of calcium superphosphate, phosphoric acid, slaked lime, calcium sulfate and control after experiment.

• Horticultural Science & Technology
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• v.32 no.2
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• pp.241-251
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• 2014

This study was carried out to develop a simple, rapid and reliable assessment model to predict cold tolerance in Pittosporum tobira, a broad-leaved evergreen commonly used in the southern region of South Korea, which can minimize the possible experimental errors appeared in a electrolyte leakage test for cold tolerance assessment. The modeling procedure comprised of regrowth test and a electrolyte leakage test on the plants exposed to low temperature treatments. The lethal temperatures estimated from the methodological combinations of a electrolyte leakage test including tissue sampling, temperature treatment for potential electrical conductivity, and statistical analysis were compared to the results of the regrowth test. The highest temperature showing the survival rate lower than 50% obtained from the regrowth test was $-10^{\circ}C$ and the lethal was $-10^{\circ}C{\sim}-5^{\circ}C$. Based on the results of the regrowth test, several methodological combinations of electrolyte leakage tests were evaluated and the electrolyte leakage lethal temperatures estimated using leaf sample tissue and freeze-killing method were closest to the regrowth lethal temperature. Evaluating statistical analysis models, linear interpolation had a higher tendency to overestimate the cold tolerance than non-linear regression. Consequently, the optimal model for cold tolerance assessment of P. tobira is composed of evaluating electrolyte leakage from leaf sample tissue applying freeze-killing method for potential electrical conductivity and predicting lethal temperature through non-linear regression analysis.

• Journal of Korean Society of Environmental Engineers
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• v.33 no.2
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• pp.71-76
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• 2011

In this study, a heavy metal stabilization treatment using waste resource stabilizing agents was utilized on army firing range soil contaminated with Pb and Cu. Both calcined oyster shells (COS; 5% w/w) and waste cow bone (WCB; 3% w/w) were applied for a wet-curing duration of 28 days. Following the stabilization treatment, the process efficiency was evaluated by various extraction methods for Pb and Cu. Neutral and weak acid extraction methods, such as water soluble extraction and SPLP, did not show positive results for heavy metal stabilization with very low leachability. On the other hand, TCLP and 0.1 N HCl extraction showed that the stabilizing agents significantly reduced the amount of the heavy metals leached from the soil, which strongly supports that the treatment efficiency is positively evaluated in acidic leaching conditions. Specifically, in the 0.1 N HCl extraction, the reduction efficiencies of Pb and Cu leaching were 99.9% and 83.9%, respectively. From the sequential extraction results, a difference between Pb and Cu stabilization was observed, which supports that Pb stabilization is more effective due to the formation of insoluble Pb complexes. This study demonstrates that the application of waste resources for the stabilization of heavy metals is feasible.

• KSBB Journal
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• v.21 no.3
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• pp.220-223
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• 2006

Lysozyme is an important antibacterial material, as effective food preservative. A number of lysozymes are found in nature such as egg white, where exists about 3.5% of egg proteins. In this study, carboxymethyl cation exchange chromatography has been used for separation of lysozyme. A simulation study by ASPEN was also performed for saving time and cost in chromatography purification experiments. Important parameters in experimental chromatography were sample loading amount, NaCl concentration, and pH of eluent. Simulation results were successfully fitted with chromatograms from experiments with change of parameters mentioned above.

• Korean Journal of Soil Science and Fertilizer
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• v.35 no.5
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• pp.264-271
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• 2002

Nitrogen releasing characteristics of polymer-coated urea(PCU) that made acrylic synthetic resins were studied in incubated soil, water and paddy soil. Also, their correlations and degradation patterns of coating material were tested. Releasing rate of nitrogen from PCU decreased with increasing coating rate. N001(coating rate 8.5%) and N003(coasting rater 6.3%) were low releasing amount at the early stage, whereas N005(coating rate 4.8%) was released over 80% within 20 days. Relationship of the releasing rate between incubated soil($25^{\circ}C$) and paddy soil could be described as follows : $Y=-0.0011X^2+2.2931X-50.264(R^2=0.9884)$ for N001, $Y=-0.0016X^2+1.1587X+5.5064(R^2=0.9805)$ for N003 and $Y=-0.03X^2+6.499X-243.22(R^2=0.9422)$ for N005, respectively (Y: release rate at field condition, X: experiment period). Relationship of the releasing rate between incubated water($30^{\circ}C$) and paddy soil can be described as follows : $Y=0.0011X^2+2.2601X-25.329(R^2=0.9884)$ for N001, $Y=-0.0306X^2+4.4994X-76.307(R^2=0.955)$ for N003 and $Y=-0.0164X^2+3.7764X-108.22(R^2=0.9422)$ for N005. After 150 days, coating materials of N001, N003, and N005 in incubated soil were degraded approximately 23%, 22% and 15%, respectively. Also The scanning electron microscope examination of coating material revealed that particle surface became gradually shattered with the time after the soil treatment.

• 한국신재생에너지학회:학술대회논문집
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• 2009.11a
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• pp.572-575
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• 2009

지층 내에 발달한 고투수성 단층은 유체, 에너지, 그리고 용질이 이동하는데 있어서 중요한 역할을 하는 지질구조이다. 따라서 고투수성 단층 주변부에서는 온천, 지열 이상대, 그리고 금속 광상 등이 형성될 가능성이 크다. 이 연구에서는 열-수리적 거동 모델링을 통하여 단층에 의한 온천 또는 지열 이상대의 형성 원인을 확인하였다. 단층의 구조에 따른 지하수 유동과 이에 따른 지층 내 열적 상태를 확인하기 위해서 단층 구조가 다른 3가지의 경우에 대해서 2차원 열-수리적 거동 정류 모델링을 수행하였다. 모델링 결과 단층 구조가 다른 3가지의 모든 경우에서 단층의 투수율이 커지면 단층대에서의 용출 온도가 초기 온도 보다 높아지는 경향을 확인 할 수 있고, 경우에 따라서 모암의 투수율 역시 용출온도에 영향을 미치는 것을 확인 하였다. 따라서 심부지열 개발을 위한 연구지역에 대해 보다 정확한 예측 모델링을 수행하기 위해서는 단층의 구조, 단층과 모암의 투수율, 그리고 수리지질학적 정보 등이 매우 중요하다고 할 수 있다.

• Ecology and Resilient Infrastructure
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• v.5 no.1
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• pp.19-24
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• 2018

Water quality is affected by the pollutants flowing into rivers since the interaction between water bodies and sediments in various environmental conditions. Especially, accumulation of sediments increases in the stagnant water areas due to a relative long hydrological retention time in the water bodies. Therefore, it is an important factor of water quality to understand characterization of the material behavior in water bodies and sediments. In this study, the objective of the conditional experiments was small and medium sized streams located in Gyeonggi-do. To estimate how the changes of fluoride behavior, depending on the pH, ion type, concentration, and clay contents. The pH results showed a trend that adsorption amount of fluorine decreased and the dissolution of fluorine increased following by pH increasing. The concentration and type of ions results showed that $Cl^-$ and $SO{_4}^{2-}$ ions had no significant effect on the adsorption ability of fluorine, the amount of dissolution was increased because $OH^-$ ion had active competition with fluorine in the reaction. The ingredient of sediment results showed that the amounts of fluoride adsorption and dissolution were reduced in samples, which contain relatively large amounts of Silt and Clay components. This means that the environmental conditions of water bodies greatly affect the adsorption and dissolution of fluoride in the sediments, so that proper management of fluoride in the sediments must precede an understanding of the environmental conditions of the water bodies.

• Korean Journal of Soil Science and Fertilizer
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• v.45 no.4
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• pp.657-663
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• 2012

To evaluate effects of water temperatures on nutrient releases of submerged plants in lake reservoir, COD, T-N and T-P releases of submerged plants were investigated for 60 days under different incubation temperatures ($5^{\circ}C$ and $25^{\circ}C$) in columns. The amounts of COD releases by Carex dimorpholepis were $60.4mg\;L^{-1}$ at $5^{\circ}C$ and $78.0mg\;L^{-1}$ at $25^{\circ}C$. In Miscanthus sacchariflorus, the amounts of COD releases were $62.5mg\;L^{-1}$ at $5^{\circ}C$ and $70.5mg\;L^{-1}$ at $25^{\circ}C$. The amounts of T-N releases in Carex dimorpholepis at $5^{\circ}C$ and $25^{\circ}C$ were 45.8 and $60mg\;L^{-1}$, respectively. In Miscanthus sacchariflorus, the amounts of T-N releases were $55.7mg\;L^{-1}$ at $5^{\circ}C$ and $61.0mg\;L^{-1}$ at $25^{\circ}C$. At $5^{\circ}C$, the amounts of T-P releases in Carex dimorpholepis and Miscanthus sacchariflorus were 5.65 and $7.10mg\;L^{-1}$, respectively. At $25^{\circ}C$, the amounts of T-P releases in Carex dimorpholepis and Miscanthus sacchariflorus were 8.70 and $8.18mg\;L^{-1}$, respectively. In the column experiment, the amounts of COD, T-N and T-P releases by submerged plants at $25^{\circ}C$ were generally higher than those at $5^{\circ}C$.