• Journal of the Korean Chemical Society
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• v.36 no.1
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• pp.24-27
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• 1992

Silver sols are aggregated by a Cu or Zn rod. This is maybe due to the reduction of $Ag^+$ ion on the surfaces of silver sols to Ag metal by oxidation-reduction reaction with Cu or Zn metal. Raman spectra of silver sols aggregated by a Cu rod have been studied. The evidence of borate and nitrate ions adsorbed on silver colloid surfaces is found. It is also found that these ions adsorbed on silver colloid surfaces are easily replaced by adsorbated added.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2004.11a
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• pp.155-158
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• 2004

질산화 (SiON) 막은 메모리와 광통신 소자 제조를 위해 활발한 응용이 기대되는 중요한 재료이다. SiON막 증착특성에 관해서는 많은 연구보고가 있었으나, 식각특성에 대해서는 그 발표가 매우 미미하다. 이에 본 연구에서는 PECVD를 이용하여 증착한 SION 박막을 Ni 마스크를 이용하여 식각하였다. 공정변수에는 소스 전력, 바이어스 전력, 압력, 그리고 $C_2F_6$ 유량 등이며, 각 변수의 실험범위는 400-1000 W, 30-90 W, 6-12 mTorr, 그리고 30-80 sccm이다. 식각률은 소스전력의 증가에 따라 233 에서 444 nm/min으로 거의 선형적으로 증가하였다. 비슷한 경향성이 바이어스 전력의 증가에 따라 관찰되었다. 이는 식각률이 플라즈마 밀도와 이온충돌 에너지에 강하게 영향을 받고 있음을 의미한다. 6-10 mTorr의 압력범위와 30-50 sccm의 $C_2F_6$ 유량범위 내에서의 식각률의 변화는 매우 미미하였다. 그러나 고압 (12 mTorr)과 고 유량 (60 sccm)에서 식각률은 크게 상승하거나 감소하였다. 전체 실험범위에서 관측된 식각률의 범위는 233-444 nm/min이었다.

• Journal of the Korean Chemical Society
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• v.33 no.4
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• pp.388-398
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• 1989

A continuous-automated method for the determination of nitrite ion using gas-sensing membrane electrode was developed. The pH electrode of tubular PVC membrane type was used as a detector of this system. The slope of linear response of the electrode measured at optimum conditions for the continuous-automated determination of nitrite ion was 63.5 mV/decade. The concentration range of linear response and detection limit were 2.5 ${\times}10^{-4}{\sim}\;7.5{\times}10^{-2}$M and $8.0{\times}10^{-5}$M, respectively. This detection system was not only less interfering to acidic gas species than other methods but also less time consumable for determination.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.23 no.1
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• pp.11-17
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• 2011

A major source of durability problems in concrete structures is the corrosion of steel by the damage of passivity layer around steel bars. As chloride ion penetration is major cause of the destruction of passivity layer, evaluation of depth and concentration profile of chloride ion is the essential factor for the service-life estimation of concrete structure. To estimate chloride ion penetration characteristics, this paper on the basis of in-situ experimental data investigated the depth and concentration profile of chloride ion penetration. The core specimens are obtained at air-zone, splash zone, and tidal zone in Wando, Masan, Incheon, Gwangyang, and donghae harbors. Colorimentric method measured the chloride ion penetration depth and ASTM C 114 evaluated the concentration profile of chloride ion. Based on experimental data, the influence of harbor location and exposure condition on chloride ion penetration is evaluated.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.332-335
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• 2005

경안천변의 충적층 지하수를 대상으로 농업활동 및 양수에 수반된 지하수 오염과 수리적 변동에 따른 수리지구화학 변화를 연구하였다. 사행하는 경안천에 의해 넓게 형성된 충적층 지역에서는 사계절 비닐하우스 농업이 활발히 이루어지고 있으며, 이를 위해 강변에 설치된 대형 관정을 통하여 지하수를 대량 양수하고 있다. 이러한 상황은 여러모로 강변여과 현장과 흡사하다. 지하수 내 주요 용존 이온의 공간적 분포는 양수에 수반된 수리적 변동과 밀접한 상관관계를 나타내었다. 즉, 대단위 양수에 의하여 충적 지하수계로의 하천수 유입이 가속화되며, 이에 따른 희석 효과에 의해 충적 지하수의 질산염 농도가 감소하는 경향을 보여주었다.

• Proceedings of the KIEE Conference
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• 1996.11a
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• pp.196-199
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• 1996

In this paper, aging characteristics of outdoor silicone rubber insulator resulting from the acid rain have been investigated with regards to nitrate ion ($NO_3$). For this purpose, silicone rubber was aged by immersing into the nitric solutions with different level ph during 1500 hours and various tests(tracking, contact angle, $tan{\delta}$, breakdown voltage, SEM, EDS, FT-IR) were performed. It was observed that the degradation was increased to ph 2.5 slightly and highly at ph 1.5. And thus, it could be expected that there is certain critical point between ph 1.5 and 2.5, which leads to throught degradation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.6015-6022
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• 2013

It has been known that there are large amount of nitric acid and valuable metals, copper in the plating waste solution of automobile wheel. As nitric acid and valuable metals are high price and toxic, they should be recovered for economics and environment. Plating waste was extracted with TBP diluted with kerosene. The concentration of nitric acid in aqueous phase was analyzed by titration method by NaOH solution (0.1~1.0N) and the amount of metals by ICP-MS and ICP-AES. The concentration of copper in plating waste were 76,850 mg/L. The concentration of nitric acid in plating waste was 1.02 M. After three step extraction was performed with 50% TBP, each organic phase was stripped three times with distilled water to obtain 48.1% of nitric acid. Purity of final nitric acid was over 99.9% by ICP analysis. After recovery of nitric acid, copper was extracted with various solvent extractors like PC 88A, D2EPHA, LIX 84 and ISE 106. Among these extractors, 92% of copper was recovered by ISE 106 after 1st extraction and 30% $H_2SO_4$ stripping. Copper ion was reduced with $N_2H_4$ to make metal powders, respectively.

• Clean Technology
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• v.15 no.3
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• pp.194-201
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• 2009

Reductive reactivity of zero-valent iron nanoparticles was investigated for removal of nitrate-nitrogen which is considered one of the major water pollutants. To elucidate the difference in reactivity between preparation methods, iron nanoparticles were synthesized respectively from microemulsion and aqueous solution of ferric ions. Iron nanoparticles prepared from microemulsion were deposited on aluminum by electrophoretic method, and their reaction kinetics was compared to that of the same nanoparticles suspended in aqueous batch reaction. With an approximation of pseudo-first-order reaction, rate constants for suspended nanoparticles prepared from microemulsion and dilute aqueous solution were $3.49{\times}10^{-2}min^{-1}$ and $1.40{\times}10^{-2}min^{-1}$, respectively. Iron nanoparticles supported on aluminum showed ca. 30% less reaction rate in comparison with the identical nanoparticles in suspended state. However, supported nanoparticles showed the superior effectiveness in terms of nitrate-nitrogen removal per zero-valent iron input especially when excess amounts of nitrates were present. Iron nanoparticles deposited on aluminum maintained reductive reactivity for more than 3 hours, and produced nitrogen gas as a final reduction product of nitrate-nitrogen.

• Journal of Environmental Impact Assessment
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• v.30 no.1
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• pp.35-48
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• 2021

In this study, the assessment of field applicability of in-situ remediation of nitrate-contaminated groundwater located in Yesan-gun was performed. Zero-valent iron/bio composite media injected PRB (Permeable Reactive Barrier) and monitoring well were installed in the contaminated groundwater site and monitored main remediation indicators during the PRB operation. Nitrate, nitrite, ammonia, Fe ion, TOC, and turbidity were analyzed and the diversity and population of microorganism in the PRB installed site were investigated for the verification of effect of injected PRB. In the study site where is an agricultural area, a river flows from west to east that forms a river boundary and the southern area has an impermeable sector. It was found that nitrate flows into the river, which is similar as groundwater flow. Simulation result for the fate of nitrate in groundwater showed steady state of nitrate arrived after 3~5 years passed. However, it is just to consider current conditions with no additional input of contaminant source, if additional input of contaminant source occurs contamination dispersion and time for steady state are expected to be increased. The monitoring results showed that Fe ion, TOC and turbidity in groundwater were not clearly changed in concentration after PRB installation, which indicates adaptability of the injected PRB for remediation of groundwater with no additional harmful effect to water quality. The concentration of nitrate maintained less than 5mg/L until 42 days after PRB installation and recovered its initial concentration after 84 days passed and showed termination of reactivity of injected zero-valent iron/bio composite media for removal nitrate. Nitrite and ammonia ions found after installation of PRB indicates reductive removal of nitrate. And the outstanding increase of microorganism diversity and population of Betaproteobacteria Class which includes denitrification microorganism explains biologically reductive removal of nitrate in injected PRB.

• Korean Journal of Environmental Agriculture
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• v.24 no.3
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• pp.253-260
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• 2005

Salt accumulation in the plastic film house soils under continuous cultivation condition causes problems such as salt damages to plants, nitrate accumulation in vegetables, groundwater contamination, etc. due to excess application of fertilizers. Objective of this research was to find an optimum adsorbent to reduce salt concentration in the soil solution of plastic film house soils, where crop injuries have been observed due to the salt accumulation. The soils were significantly high in available P $(1,431{\sim}6,516mg\;kg^{-1}),\;NO_3-N\;(117.60{\sim}395.73mg\;kg^{-1})$, exchangeable Ca $(4.06{\sim}11.07\;cmol_c\;kg^{-1})$ and Mg $(2.59{\sim}18.76\;cmol_c\;kg^{-1})$, as compared to those of the average upland soils in Korea. Soils were treated with each of adsorbent such as ion-exchange resin, zeolite, rice bran, etc. at 2% level and prepared into saturated-paste samples. After equilibrium, soil solution was vacuum-extracted from the soil and measured for changes of the pH, EC, and concentrations of $Ca^{2+},\;Mg^{2+},\;K^+,\;Na^+,\;{NH_4}^+,\;{PO_4}^{3-}\;and\;{NO_3}^-$. Rice bran effectively removed ${PO_4}^{3-}\;and\;{NO_3}^-$ in the soil solution up to 100%. Efficiency was decreased in the orders of rice bran > ion-exchange resin > zeolite. Removal efficiencies of zeolite and ion-exchange resin for $Ca^{2+}$ were ranged from 1 to 65% and from 7 to 61%, respectively. Ion-exchange resin was also effective for removing $Mg^{2+},\;K^+,\;Na^+,\;and\;{NH_4}^+$. Overall results demonstrated that rice bran and ion-exchange resin could be applicable for salt accumulated soil to remove the respective anion and cation.