• Journal of Welding and Joining
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• 제15권5호
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• pp.124-133
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• 1997

Corrosion behavior of welded SWS400 steel used for bridges was studied in a range of the acid-rain environment using immersion, potentiodynamic polartization, polarization resistance, and galvanic corrosion tests. The SWS400 steel exhibited active corrosion behavior in the range of acid-rain environment, i.e. no passivation. As the results of immersion corrosion test, Tafel extrapolation method, and polarization resistance measurement, the average corrosion rats of the steels were 0.31-0.72 mm/year in the pH of 4-5, and 0.17 mm/yera in the pH 6, respectively. The steel showed a resistance to corrosion in the pH 6. The observed active behavior of SWS400 steel in chloride-containing environment indicated that the chloride ions exerts a detrimental influence on the formation of passive films. Galvanic corrosion was observed between the weld and the base metals because the weld is anodic to the base metal.

• Bulletin of the Korean Chemical Society
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• 제7권1호
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• pp.66-69
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• 1986

The reaction of potassium trialkoxyborohydrides of varying steric requirements with lithium chloride in tetrahydrofuran(THF) was examined in detail to establish the generality of this synthesis of the corresponding lithium trialkoxyborohydrides. The metal ion exchange reaction between potassium triisopropoxyborohydride and lithium chloride in THF proceeded instantly at room temperature and the corresponding lithium salt was very stable toward disproportionation. However, for R = s-Bu, t-Bu and 2-methylcyclohexyl, with increasing steric requirement, the lithium derivatives were unstable and thus dissociated into $(RO)BH_3^-\;and\; (RO)_4B^-$. The stereoselectivity of lithium triisopropoxyborohydride(LIPBH) in the reduction of representative cyclic ketones was examined and compared with that of the potassium derivative.

• 한국방사성폐기물학회:학술대회논문집
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• 한국방사성폐기물학회 2018년도 추계학술논문요약집
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• pp.299-300
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• 2018

Electrochemical behaviors of Nb ion in the $LiCl-KCl-NbCl_5$ molten salt were examined. Cyclic voltammograms with different scan rates and scan range at $450^{\circ}C$ showed possible electrochemical redox reactions which were identified by comparison to the literature data. Peak potentials for each redox reaction were consistent with the literature, but some redox reactions were not clearly defined due to the formation of subchloride compound in chloride salt. The electrochemical behaviors of Nb ion related to the subchloride formation as well as Nb metal deposition will be investigated for the future work.

• Korean Chemical Engineering Research
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• 제50권5호
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• pp.795-801
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• 2012

가장 널리 이용되고 있는 금속나노입자 중 금과 은을 친환경용매인 RTILs (room temperature ionic liquids)를 이용하여 제조하고자 하였다. 본연구에서는 두 종류의 이온성 액체, 즉 비수용성인 [BMIM][$PF_6$] (1-Butyl-3-methylimidazolium hexafluorophosphate)과 수용성인 [BMIM][Cl](1-Buthy-3-methylimdazolium chloride)를 이용하여 리간드로 안정화된 금속 나노입자를 제조하고자 하였다. 이 중 [BMIM][Cl]은 논연구에서 Dupont 등의 방법으로 직접 합성하여 물성 분석 후 사용하였으며, [BMIM][$PF_6$]은 완제품을 구입하여 사용하였다. 금과 은의 나노입자들을 습식으로 제조하는 경우의 Brust et al.[6]의 방법이 널리 알려져 있으며, 본 연구에서도 이를 기초로 하여 나노입자를 제조하였다. [BMIM][$PF_6$]로 나노입자 제조시는 이 용매가 물에 녹지 않으므로 기본적으로는 유기용매 대신 [BMIM][$PF_6$]를 사용하는 것 외에는 Brust 등과 같은 방법제조하였다. [BMIM][Cl]로 나노입자를 제조하는 경우는 이 용매가 수용성이므로 상전이제와 ethanol은 사용하지 않고 입자를 제조하였다. 이렇게 얻어진 나노입자들의 경우 [BMIM][$PF_6$]로 합성한 경우는 FT-IR, UV-vis, TEM 그리고 TGA 분석을 통하여 Brust 등이 합성한 경우와 유사한 결과를 얻었지만, [BMIM][Cl]의 경우는 형태학적으로 다른 나노입자를 얻었다. 기존의 나노입자를 제조하는 과정에서 이용되는 유기용매를 이용하는 방법을 그린용매인 이온성 액체로 대체할 수 있다는 가능성을 확인할 수 있었고, 이온성 액체의 특성에 따라서 형태학적으로 다른 입자를 얻을 수 있었으나, 이 부분은 추후 더 많은 연구가 필요하다.

• 한국응용과학기술학회지
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• 제27권2호
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• pp.208-215
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• 2010

EAF dust which is contained around 30% of zinc, 15% of iron and 3% of lead individually, is chemically treated by ammonium chloride, ammonia water, ammonia gas and carbon dioxide, and also tested and identified the ratios of the recovery of In by applied the variations of particle size, pH and heating temperature as well, in order to getting optimized recovery of the In metal after performing all of those processes. Experimental results showed that the rate of Zn recovery is 97% when the mixture of 1.3 of $NH_4Cl$/EAF is heated to the temperature of $400^{\circ}C$ and leached by water, and 95% recovery of In when ammonia gas and carbon dioxide is added simultaneously and adjust the 9.5 of pH to the same mixture above. For the purpose of remove the impurities in the mixed sample, which is prepared by the two samples, indicated above showing as the ratio of 95% and 97% recovery, in case of applied the cementation process to it, and also by electrolytic process, produced the In plate of 95~97%, and acquired 99-99.5% of In metal ingot finally by applied the heating process at $470{\sim}500^{\circ}C$.

• 한국전기전자재료학회논문지
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• 제24권4호
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• pp.328-332
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• 2011

The formation of front metal contact silicon solar cells is required for low cost, low contact resistance to silicon surface. One of the front metal contacts is Ni/Cu plating that it is available to simply and inexpensive production to apply mass production. Ni is shown to be a suitable barrier to Cu diffusion into the silicon. The process of Ni electroless plating on front silicon surface is performed using a chemical bath. Additives and buffer agents such as ammonium chloride is added to maintain the stability and pH control of the bath. Ni deposition rate is found to vary with temperature, time, utilization of bath. The experimental result shown that Ni layer by SEM (scanning electron microscopy) and EDX analysis. Finally, plated Ni/Cu contact solar cell result in an efficiency of 17.69% on $2{\times}2\;cm^2$, Cz wafer.

• Corrosion Science and Technology
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• 제20권6호
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• pp.361-366
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• 2021

Localized corrosion behavior of Ni-based Inconel 718 alloy was investigated by electrochemical anodic polarization techniques in NACE TM 0177 A solution of 5 wt% NaCl + 0.5 wt% acetic acid at room temperature. After the solution heat treated at 1080 ℃ for 2.5 h, Inconel 718 was age-hardened at 780 ℃ for 8 h. The microstructure of the alloy surface was investigated by optical microscopic or scanning electron microscopic technique. The austenitic phase with the presence of metal carbides was observed on the surface of Inconel 718. Metal-carbides such as Nb-Mo and Ti-carbide with diameters of approximately 10 and 3 ㎛, respectively, were formed in Inconel 718. Anodic polarization results revealed that localized corrosion was observed at the interface between austenitic phase of a substrate and metal carbides. Difference in electrochemical property between a metal carbide and an austenitic substrate could provide an initiation site for localized corrosion of Inconel 718 surface.

• 폴리머
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• 제30권1호
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• pp.64-69
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• 2006

길이가 다른 폴리메틸렌 가지로 연결되고 chloride 대신 aryloxy 기가 치환된 dinuclear half-titanocene $[(\eta^5-cyclopentadienyl)(aryloxy)TiCl_2]_2[(CH_2)_n]$ (n=3, n=6, n=0)를 합성하고 이들의 중합특성을 조사하였다. Chloride 대신 치환된 aryloxy기는 2,6-diisopropylphenoxy를 사용하였다. 합성된 3 종류의 dinuclear half-titanocene은 $^1H\;NMR,\;^{13}C\;NMR$, 원소분석, 그리고 질량분석을 통해 구조와 조성을 규명하였다 3가지 화합물의 중합특성을 비교 조사하기 위해 조촉매(MMAO) 존재 하에서 스티렌의 중합실험을 수행하였으며, 그 결과 (i) 합성된 3 가지 촉매들은 모두 스티렌 중합으로부터 SPS(syndiotactic polystyrene)를 제조하는데 성공적인 촉매였고, (ii) 3화합물 중에서 다리리간드의 길이가 가장 긴 화합물 6이 가장 높은 활성을 나타내었으나 가장 낮은 분자량의 SPS를 생성하였으며, (iii) aryloxy로 치환된 촉매가 치환되기 전의 chloride화합물에 비해 더 높은 활성을 보이는 치환체의 효과가 관찰되었다 이 결과들은 dinuclear half-titanocene에 있어서의 촉매 특성은 다리리간드의 종류와 함께 티타늄에 결합된 음이온의 특성도 촉매의 중합특성에 중요한 영향을 미치는 것임을 보여주는 것이다.

• 한국식품영양과학회지
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• 제36권6호
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• pp.753-758
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• 2007

전남지역에서 생산된 천일염의 안전성에 대한 기초자료를 제공하기 위해 전남의 주 생산지에서 생산된 천일염 433 종을 대상으로 NaCl 함량 및 중금속(Pb, Cd, As, Hg) 함량을 조사하였다. NaCl 함량은 대부분 80%대 수준이었으며 전체의 63%의 천일염이 $80{\sim}85%$ 함량을 보여 가장 높은 분포를 나타내었다. Pb은 77%의 시료에서 검출되지 않았고 Pb이 검출된 천일염은 모두 기준치인 2 ppm 이하로 나타났다. Cd은 78%의 시료에서 검출되지 않았으며 3곳을 제외하고는 대부분 기준치 이하로 검출되었다. As는 4종의 시료에서만 검출되었는데 모두 기준치에 못 미치는 0.1 ppm 이하로 나타났고, Hg은 모든 천일염에서 검출되지 않았다. NaCl 함량과 Pb 농도는 지역별로 차이를 보였고 Cd, As, Hg은 지역간에 차이가 나타나지 않았다. 따라서 전남에서 생산된 천일염은 생산 지역 간의 다소의 차이는 있으나 중금속오염에 대하여 안전한 수준인 것으로 평가되었다.

• The Journal of Advanced Prosthodontics
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• 제9권2호
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• pp.118-123
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• 2017

PURPOSE. To investigate the effect of non-thermal atmospheric pressure plasma (NTAPP) treatment on shear bond strength (SBS) between resin cement and colored zirconia made with metal chlorides. MATERIALS AND METHODS. 60 zirconia specimens were divided into 3 groups using coloring liquid. Each group was divided again into 2 sub-groups using plasma treatment; the experimental group was treated with plasma, and the control group was untreated. The sub-groups were: N (non-colored), C (0.1 wt% aqueous chromium chloride solution), M (0.1 wt% aqueous molybdenum chloride solution), NP (non-colored with plasma), CP (0.1 wt% aqueous chromium chloride solution with plasma), and MP (0.1 wt% aqueous molybdenum chloride solution with plasma). Composite resin cylinders were bonded to zirconia specimens with MDP-based resin cement, and SBS was measured using a universal testing machine. All data was analyzed statistically using a 2-way ANOVA test and a Tukey test. RESULTS. SBS significantly increased when specimens were treated with NTAPP regardless of coloring (P<.001). Colored zirconia containing molybdenum showed the highest value of SBS, regardless of NTAPP. The molybdenum group showed the highest SBS, whereas the chromium group showed the lowest. CONCLUSION. NTAPP may increase the SBS of colored zirconia and resin cement. The NTAPP effect on SBS is not influenced by the presence of zirconia coloring.