• Journal of the Mineralogical Society of Korea
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• v.14 no.1
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• pp.12-20
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• 2001

충북 영동군 동창광산에서 산출되는 일라이트(illite)광선의 표면화학특성을 전위차 적정 실험과 FITEQL3.2 프로그램을 이용하여 연구하였다. 정량 Xtjs 회절 분석에 의한 일라이트 광석의 광물조석은 석영 46.6% 일라이트 41.6% 카올리나이트(kaolinite) 11.8%이며 $N_2$BET 방법에 의하여 구한 비표면적은 $6.52 m^2$g이다. 전위차 적정 실험결과를 그란(Gran)법을 적용하여 구한 일라이트광석의 영전하점($pH_{pznpc}$ )은 pH 3.9 총표면 자리 밀도는 21.24 sites/$nm^2$이다. 표면 복합체 모델중 일정 용량 모델을 적용해 일라이트 광석의 표변 특성에 알맞는 모델을 찾아보았다. 일라이트 광석의 표면을 사면체 자리와 팔면체 자리로 나누어 설정한 2sites$-3pK_{ a}$s 모델은 변수값이 수렴되지않았으므로 부적절하다고 판단된다. 일라이트 광석의 표면을 하나의 균질한 흡착표면으로 가정해서 설정한 1 site -1 $K_{a}$ 와 1 site -2 $pK_{a}$ s 모델 사이에는 뚜렷한 차이는 없지만, 1 site -1 $pK_{a}$ 모델의 WSOS/DF 값이 17, 1 site - 2 $pK_a{s}$ 모델은 26으로서 앞 모델이 보다 적절하다. 이 결과는 일라이트 광석 표면에서 수소의 해리와 첨가 반응 중 첨가 반응을 무시하여도 표면반응을 설명하는 데 큰 무리가 없음을 시사한다. 가장 적절하다고 판단되는 1 site -1 $pK_{a}$ 모델의 $pK_{a}$ 값은 4.17, specific capacitance는 $6F/m^2$ 표면 자리 농도는 $1.15\Times10^{-3}$ mol/L 이다.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.6 no.6
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• pp.478-485
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• 2005

This paper analysed the ionized fields around HVDC transmission line by the use of the charge simulation method. As this is very complex and expressed by a non-linear partial differential equations, it is hard to solve problems analytically. So, we developed a computer program which can apply in multi-polar HVDC transmission line with conductor bundles and calculated conductor surface gradient, corona current density and ion charge density to prove validity of a proposed algorithm in this paper.

• Clean Technology
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• v.20 no.2
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• pp.130-135
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• 2014

It is investigated that the surface properties of mercaptopyruvic-acid layer formed on gold surfaces may make an effect on the distribution of either gold particle adsorbed to the zirconia surface or vice versa. For the investigation, the atomic force microscope was used to measure the surface forces between the surfaces as a function of the salt concentration and pH value. The forces were quantitatively analyzed with the derjaguin-landau-verwey-overbeek (DLVO) theory to estimate the electrostatic properties, potential and charge density, of the surfaces for each condition of salt concentration and pH value. The estimatedvalue dependence on the salt concentration was explained with the law of mass action, and the pH dependence was interpreted with the ionizable groups on the surface. The salt concentration dependence of the surface properties, found from the measurement at pH 4 and 8, was predictable from the law. It was found that the mercaptopyruvic-acid layer had higher values for the surface charge densities and potentials than the zirconia surfaces at pH 4 and 8, which may be attributed to the ionizedfunctional-groups of the mercaptopyruvic-acid layer.

• Proceedings of the KIEE Conference
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• 1981.07a
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• pp.107-109
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• 1981

• Applied Chemistry for Engineering
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• v.25 no.6
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• pp.607-612
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• 2014

The physical properties of mercaptoundecanoic-acid layer formed on gold surfaces, which may affect the distribution of either gold particles adsorbed to the zirconium dioxide surface or vice versa, were investigated. To conduct this investigation, the surface forces were measured between the surfaces with respect to the salt concentration and pH value using atomic force microscope (AFM). The forces were quantitatively converted by the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory to the surface potential and charge density of surfaces. The converted-value dependence on the salt concentration and pH was described with the law of mass action, and the dependence was consistent with the theoretical prediction. It was found that the mercaptoundecanoic-acid layer had higher values for the surface charge densities and potentials than the $ZrO_2$ surfaces, which may be attributed to the ionized-functional-groups of the mercaptoundecanoic-acid layer.

• Korean Journal of Soil Science and Fertilizer
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• v.26 no.3
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• pp.160-171
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• 1993

Surface charge characteristics of Ultisol(Luisiana soil from Philippines), Alfisol(Maahas soil from Philippines), and Inceptisol(Yongii soil from Korea) were studied by way of potentiometric titration, backtitration technique, and ion adsorption method(or CEC - AEC method). The PZNC(point of zero net charge) values determined by ion adsorption method were much lower than the natural pHs in all soils, indicating that all soil samples bore net negative surface charge. The PZSE (point of zero salt effect) values determined by potentiometric titration and backtitration technique were identical in Luisiana and Yongii soils but not in Maaghas soil. All soils showed higher PZSE values than PZNC values probably due to the influence of permanent negative charge. The permanent charge calculated by the theory of Uehara and Gillman (1980) occupied quite low portion of the CEC measured at pH 7 in all soils. Backtitration technique corrected errors of potentiometric titration at extreme pH. However, it still overestimate the surface charge compared with ion adsorption method. Therefore, the ion adsorption method was recommanded for the surface charge measurement of the usual soils which have high negative charge components.

• Journal of Adhesion and Interface
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• v.20 no.4
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• pp.155-161
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• 2019

Understanding charge transport anisotropy at the interface of conjugated nanostructures basically gives insight into structure-property relationship in organic field-effect transistors (OFET). Here, the anisotropy of the field-effect mobility at the interface between 6,13-bis(triisopropylsilylethynyl) pentacene (TIPS-pentacene) single crystal with cofacial molecular stacks in a-b basal plane and SiO gate dielectric was investigated. A solvent exchange method has been used in order for TIPS-pentacene single crystals to be grown on the surface of SiO₂ thin film, corresponding to the charge accumulation at the interface in OFET structure. In TIPS-pentacene OFET, the anisotropy ratio between the highest and lowest measured mobility is revealed to be 5.2. By analyzing the interaction of a conjugated unit in TIPS-pentacene with the nearest neighbor units, the mobility anisotropy can be rationalized by differences in HOMO-level coupling and hopping routes of charge carriers. The theoretical estimation of anisotropy based on HOMO-level coupling is also consistent with the experimental result.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.409-409
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• 2012

최근 나노크기의 미세구조 가공기술이 발달함에 따라 다양한 응용을 위한 나노소재/구조가 활발히 연구 되고 있다[1]. 그 중에서 실리콘 나노선은 태양전지, 메모리, 트랜지스터 그리고 광 공진기에 쓰일 수 있는 소재로서 기존의 실리콘 가공기술을 바로 사용할 수 있을 뿐 아니라[2], 비용 면에서 탁월한 잇점이 있기 때문에 주목 받고 있는 소재이다. 실리콘 나노선의 물리적 특성을 연구하기 위한 많은 연구가 진행되었지만, 매우 작은 크기와 높은 표면적-부피비율로 인해 생긴 독특한 특징을 완전히 이해하기에는 아직 부족한 점이 많다. 실리콘 나노선의 전류-전압특성에 영향을 미치는 요소는 도핑농도, 표면상태, 채널의 크기 등으로 다양한데, 이번 연구에서는 실리콘 나노선의 표면환경이 공기와 물 두 종류로 매질에 접하고 있을 경우에 대하여 각각 전류-전압을 측정하였다. 물이 공기와 다른 점은 크게 두 가지로 볼 수 있다. 첫째로 물의 경우에는 물에 용해된 수소이온과의 화학반응을 통하여 실리콘 표면전하가 유도되며 pH 값에 민감하게 변화한다. 둘째로 물의 유전율은 공기의 80배로서 표면부근에서의 전기장분포가 많이 왜곡된다. 이를 위하여 SOI를 기반으로 채널길이 $5{\mu}s$, 두께 40 nm, 너비 100 nm인 실리콘 나노선을 일반적인 반도체공정을 사용하여 제작하였다. 나노선의 전기적 특성 실험은 Semiconductor Parameter Analyzer (Agilent, 4155C)를 사용하여 전류-전압특성을 표면 상태를 변화시키면서 측정하였다. 실험을 통해 실리콘 나노선은 물과 공기 두 가지 표면환경에 따라 전류-전압특성이 확연히 변화하는 것을 볼 수 있었다. 동일한 전압 바이어스에서 표면에 물이 있을 때가 공기 있을 때 보다 훨씬 증가한 전류를 얻을 수 있었고(3V에서 약 2배), 비선형적인 전류-전압특성이 나타남을 관찰하였다. 본 발표에서는 이러한 실험결과를 표면에서의 전하와 정전기적인 효과로서 정성적으로 설명하고, 전산모사결과와 비교분석 하고자 한다.

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.538-543
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• 2014

It is investigated that that the physical properties of Glutathione layer formed on gold surfaces may make an effect on the distribution of either gold particle adsorbed to the $ZrO_2$ surface or vice versa with the adjustment of the electrostatic interactions. For the investigation, the atomic force microscope (AFM) was used to measure the surface forces between the surfaces as a function of the salt concentration and pH value. The forces were quantitatively analyzed with the Derjaguin-Landau-Verwey-Overbeek (DLVO) theory to estimate the surface potential and charge density of the surfaces for each condition of salt concentration and pH value. The estimated-value dependence on the salt concentration was described with the law of mass action, and the pH dependence was explained with the ionizable groups on the surface. The salt concentration dependence of the surface properties, found from the measurement at pH 4 and 8, was consistent with the prediction from the law. It was found that the Glutathione layer had higher values for the surface charge densities and potentials than the zirconium dioxide surfaces at pH 4 and 8, which may be attributed to the ionized-functional-groups of the Glutathione layer.

• Journal of the Korean institute of surface engineering
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• v.26 no.3
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• pp.135-142
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• 1993

탄소강 및 Nickel 음극에서 아연의 전착특성에 대하여 조사하였다. 황산아연 및 염화아연용액속에서 회전전극을 사용하여 실험한 결과 아연의 평형전위 이전에서 전착이 일어나는 소위 Underpotential Deposition 현상이 관찰되었다. 또한 이렇게 전착이 일어난 아연층은 평형상태에서 일정한 두께로 제한되는데 전착전압에 따른 전착층의 전하량을 계산한 결과 다층흡착구조과 유사한 경향을 나타내었다.