• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.153-153
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• 2000

Si 산화는 반도체 공정상 필요한 과정으로 산업적으로나 학문적으로 중요하고 많이 연구되었다. 이중에서 Si(1110-7x7표면에서 초기 흡착된 산소는 준안정적 상태로 존재하며 표면온도, 산소의 노출량 그리고 진공도에 따라 그 수명이 제한된다. 이러한 준안정적 상태의 산소의 화학적 성질은 여러 표면분석장비가 동원되어 연구되었으나 아직까지 논쟁이 되고 있다. 이 경우 산소가 어떤 상태로 존재하는가는 표면화학종을 검출함으로서 해결될 수 있다. 저에너지 Cs+ 이온 반응성 산란은 이러한 요구를 충족시킬수 있는 가장 적합한 실험 방법중의 하나이다. 저에너지 Cs+ 이온 산란의 특징 중의 하나는 입사된 Cs+ 이온이 표면에 흡착된 화학종과 충돌후 탈착되면서 반응을 하여 송이 이온을 형성한다는 것이다. 이 송이 이온을 관측함으로서 표면에 존재하는 화학종을 알아 낼 수 있다. 이에 산소가 흡착된 Si(111)-7x7 표면에서의 산소의 준안정적 상태가 저에너지 Cs+ 이온 산란 실험을 통하여 연구되었다. 실험은 0.2-2L(1Langmuir = 10-6 Torr x 1 sec) 산소 노출량과 -15$0^{\circ}C$ - $25^{\circ}C$의 표면온도 그리고 5eV - 20eV의 Cs+ 이온 충돌에너지에서 CsSiO+ 이온이 유일한 생산물로서 검출되었다. CsSiO+ 이온은 입사된 Cs+ 이온과 표면에 존재하는 SiO 분자가 충돌 후 반응하여 탈착된 것으로 생각된다. 이것은 낮은 산소 노출량 즉, 초기 산화 단계에서 SiO가 표면에 존재한다는 것을 의미한다. 즉, 산소 분자는 산화단계의 초기에 해리되어 표면에 흡착되고 선구물질인 SiO를 형성함을 제시한다. 최근의 이론적 계산인 density functional calculation에서도 산소분자가 Si(111)-7$\times$7 표면의 준안정적 산화상태의 선구물질일 가능성을 배제한다. 이는 본 저에너지 Cs+ 이온 반응성 산란실험을 뒷받침하는 계산 결과이다. 높은 Cs+ 이온 충돌에너지에서 CsSi+, Si+, SiO+, Si2+, Si2O+ 등이 추가로 검출되었다. 이는 CsSi 이온을 제외하고 수 keV의 충돌에너지를 사용하는 이차 이온 질량 분석법과 비슷한 결과이다.

• Journal of the Korean Chemical Society
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• v.35 no.4
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• pp.301-307
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• 1991

The solubilities of the n-propyl iodide in nitrobenzene and m-xylene have been measured at 8$^{\circ}$, 15$^{\circ}$ and 25$^{\circ}C$ in the presence and the absence of gallium iodide. When gallium iodide does not exist in the system, the solubility of n-propyl iodide in m-xylene is greater than in nitrobenzene, indicating a stronger interaction of n-propyl iodide with m-xylene than that with nitrobenzene. It could be thought that n-propyl iodide forms unstable complex with gallium iodide in the presence of gaillium iodide in the system. This complex has been assumed in various ways and evaluated, that instability constant (K value) is relatively certain under the assumption of 1:1 complex, n-C$_3H_7I{\cdot}GaI_3$. Therefore, the complex would form the following equilibrium in the solution: n-C$_3H_7{\cdot}GaI _3{\rightleftharpoons}n-C_3H_7I+1/2Ga_2I_6$ the instability of the complex of n-propyl iodide with gallium iodide is compared with similar complexes of gallium iodide with methyl iodide. The changes of enthalpy, free energy and entropy for the dissociation of the complex are also calculated.

• Journal of the Korean Chemical Society
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• v.20 no.4
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• pp.270-276
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• 1976

The absorption spectra and the dissociation constants of various sulfophthaleins have been measured in the presence of a cationic surfactant. In the presence of 2.0 ${\times}$ 10-3 M zephiramine and an ionic strength of 0.05 at 25${\pm}1^{\circ}C$ the absorption maxima of the basic forms are shifted to red by 6${\sim}$21 nm and their molar absorptivities are increased, while the absorption maxima of the yellow forms are shifted to blue by 4${\sim}$20 nm and their molar absorptivities are decreased. The decreases in pKa values are of the order of ranging -1.38${\sim}$0.37. The characteristic of the observed changes has been explained by the assumption that the dye molecule adsorbed on micellar surface forms a stable coplanar structure easily and then the conjugation in the dye molecule is elevated.

• Analytical Science and Technology
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• v.13 no.2
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• pp.173-178
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• 2000

A new open-chain ligand containing two phenol groups, 1, 14-Bis (2-hydroxybenzyl)-2, 6, 9, 12-tetraazatetradecane(bsated) was synthesized as its tetrahydrochloride salt and characterized by elemental analysis, mass, infrared and NMR. Its proton dissociation constants ($logK^n{_H}$) and stability constants ($logK_{ML}$) toward $Co^{2+}$, $Ni^{2+}$, $Cu^{2+}$ and $Zn^{2+}$ were determined at $25^{\circ}C$ and 0.10M($KNO_3$) ionic strength in aqueous solution by potentiometry. The X-ray structure of its copper (II) complex [Cu(bsated)]$(ClO_4)_2$ was reported: Monoclinic space group $P2_1/n$, $a=17.856(4){\AA}$, $b=17.709(1){\AA}$, $c=8.539(2){\AA}$, $V=2700(2){\AA}$ with Z=4. Electrochemical studies of [Cu(bsated)]$(ClO_4)_2$ complex in dimethyl sulfoxide (DMSO) solution containing tetrabutylammonium perchlorate (supporting electrolyte) were carried out by cyclic voltammograms (CV) and normal pulse voltammetry (NPV).

• Journal of Fisheries and Marine Sciences Education
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• v.10 no.1
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• pp.31-52
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• 1998

In this paper, we analyzed the relationships between the fishing ground formation and the sea condition information, surface, mid and bottom layer temperature that is necessary for fishing point selection of angling to catch squid in the East Sea. There was a little differences between temperature measured by every fishing boat on fishing operating and prompt reports of fishing and sea condition about fishing ground formation of angling. And then the result examined by using SST that is a important information of sea condition for the fishing position selection follows as ; We knew, even if the differencs of sea condition each year, SST with a lot of fishing boats was generally within the extnet of $2^{\circ}C$. But the result examined by the limit time about the temperature of mid and bottom layer for the groups of fishing boats not to measure and for the near sea measurement to be done only within EEZ waters follows as ; About the temperature of 50m layer on early in June and July in operating waters of the group of fishing boats, the fishing ground was formed from $10^{\circ}C$ to $12^{\circ}C$ between warm waters and cold waters, afterwards we can seize that the fishing ground was moving to waters from $5^{\circ}C$ to $8^{\circ}C$ at near of polar front. In the coastal waters, we knew that fishing ground is formed to waters from $10^{\circ}C$ to $12^{\circ}C$ at the southern of polar front about the temperature of 50m layer.

• Applied Chemistry for Engineering
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• v.8 no.3
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• pp.382-388
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• 1997

Reforming of propane by carbon dioxide using NiO/${\gamma}$-$A1_2O_3$ was carried out in a pulse or continuous kid bed reactor. NiO/${\gamma}$-$Al_2O_3$ showed higher dissociation ability of $CO_2$ than NiO/${\gamma}$-$Al_2O_3$, and the former exhibited higher conversion of propane than the latter. The presence of oxygen in the reaction mixture of propane and $CO_2$ increased the conversion of propane and reduced the amount of carbon deposit on the catalyst surface. Mechanical mixture catalyst of NiO/${\gamma}$-$Al_2O_3$ and $Ga_2O_3$ showed higher stability to deactivation than NiO/${\gamma}$-$Al_2O_3$ itself. The synergistic effect between NiO/${\gamma}$-$Al_2O_3$ and $Al_2O_3$ was also observed in this study.

• Korean Journal of Environmental Agriculture
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• v.18 no.2
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• pp.191-195
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• 1999

An integrated wastewater treatment pond system is developed for treatment and recycling of excreta from dairy cattle. It is composed of three ponds in series. A pit with a capacity of $10m^3$, 2-day hydraulic residence time, and overflow velocity of $1.5m^3m^{-2}day^{-1}$ is located internally in primary pond. It is designed for efficient sludge sedimentation and effective methane fermentation. It receives $5m^3/day$ of diluted cattle excreta by the water used for clearing stalls. A submerged gays collector for the recovery of methane is installed on the top of the pit. The average BOD_5 concentration of influent is 398.7mg/l. That of the effluent from primary pond is 49.2mg/l. About 88% of BOD_5 are removed in primary pond. It is assumed that about 60% of the influent BOD_5 is removed in the pit and that almost all of the carbon of the removed BOD_5 in the pit is converted to methane and carbon dioxide. Methane fermentation of the pit is well established at $16^{\circ}C$. This phenomena results from temperature stability, complete anaerobic condition, and neutral pH of the pit. Gas from the collector is almost 90% methane, less than 9% nitrogen, and less than 1% carbon dioxide. Thus a purified methane is produced, which can be used as energy source.

• Journal of the Korean Chemical Society
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• v.27 no.5
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• pp.340-344
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• 1983

It has been found that both of the iridium (Ⅰ) complexes, Ir$(ClO_4$)(AN)(CO)$(Ph_3P)_2$(AN = $CH_2$CHCN, $Ph_3P = (C_6H_5)_3$P) and [Ir(AN)(CO)$(Ph_3P)_2]ClO_4$, react with $Cl^-$ to give IrCl(AN)(CO)$(Ph_3P)_2$, and [Ir(AN)(CO)$(Ph_3P)_2]ClO_4$ dissociates AN to yield Ir$(ClO_4)(CO)(Ph_3P)_2$ in the absence of excess AN added, and Ir$(ClO_4)(CO)(Ph_3P)_2$ reacts with $Cl^-$ to produce IrCl(CO)$(Ph_3P)_2$. It is suggested that the catalytic polymerization of AN with Ir$(ClO_4)(AN)(CO)(Ph_3P)_2$ proceeds through the formation of [(CO)(Ph_3P)_2$Ir(-CH=CHCN)(H)($CH_2$=CHCN)]Cl$O_4$ followed by the formation of iridium(alkyl)(alkenyl) type complex which undergoes a reductive elimination to produce the polymer of acrylonitrile.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.188-188
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• 2000

DLC (Diamond-Like Carbon) 박막은 높은 경도와 가시광선 및 적외선 영역에서의 광 투과도, 전기적 절연성, 화학적 안정성 및 저마찰.내마모 특성 등의 우수한 물리.화학적인 물성을 갖고 있기 때문에 여러 분야의 응용연구가 이루어지고 있다. 이러한 DLC 박막을 제작하는 과정에는 여러 가지가 있으나, 본 연구에서는 ECR-PECVD electron cyclotron resonance plasma enhanced chemical vapor deposition) 방법을 사용하였다. 이것은 최근에 많이 이용되고 있는 방법으로, 이온화률이 높을뿐만 아니라 상온에서도 성막이 가능하고 넓은 진공도 영역에서 플라즈마 공정이 가능한 장점이 있다. 기판으로는 4" 크기의 S(100)를 사용하였고, 박막을 제작하기 전에 진공 중에서 플라즈마 전처리를 하였다. 플라즈마 전처리는 Ar 가스를 150SCCM 주입시켜 5$\times$10-1 torr 의 진공도를 유지시키면서, ECR power를 700W로 고정하고, 기판 bias 전압을 -300 V로 하여 5분 동안 기판을 청정하였다. DLC 박막은 ECR power를 700W. 가스혼합비와 유량을 CH4/H2 : 10/100 SCCM, 증착시간을 2시간으로 고정하고, 기판 bias 전압을 0, -50, -75, -100, -150, -200V로 변화시켜가면서 제작하였다. 이때 ECR 소스로부터 기판까지의 거리는 150mm로 하였고, 진공도는 2$\times$10-2torr 였으며, 기판 bias 전압은 기판에 13.56 MHz의 RF power를 연결하여 RF power에 의해서 유도되는 negative DC self bias 전압을 이용하였다. 제작된 박막을 Auger electron spectroscopy, elastic recoil detection, Rutherford backscattering spectroscopy, X-ray diffraction, secondary electron microscopy, atomic force microscoy, $\alpha$-step, Raman scattering spectroscopu, Fourier transform infrared spectroscopy 및 micro hardness tester를 이용하여 기판 bias 전압이 DLC 박막의 특성에 미치는 영향을 조사하였다. 분석결과 본 연구에서 제작된 DLC 박막은 탄소와 수소만으로 구성되어 있으며, 비정질 상태임을 알 수 있었다. 기판 bias 전압의 증가에 따라 박막의 두께가 감소됨을 알 수 있었고, -150V에서는 박막이 거의 만들어지지 않았으며, -200V에서는 기판 표면이 식각되었다. 이것은 기판 bias 전압과 ECR 플라즈마에 의한 이온충돌 효과 때문으로 판단되며, 150V 이하에서는 증착되는 양보다 re-sputtering 되는 양이 더 많을 것으로 생각된다. 기판 bias 전압을 증가시킬수록 플라즈마에 의한 이온충돌 현상이 두드러져 탄소와 결합하고 있던 수소원자들이 떨어져 나가는 탈수소화 (dehydrogenation) 현상을 확인할 수 있었으며, 이것은 C-H 결합에너지가 C-C 결합이나 C=C 결합보다 약하여 수소 원자가 비교적 해리가 잘되므로 이러한 현상이 일어난다고 판단된다. 결합이 끊어진 탄소 원자들은 다른 탄소원자들과 결합하여 3차원적 cross-link를 형성시켜 나가면서 내부 압축응력을 증가시키는 것으로 알려져 있으며, hardness 시험 결과로 이것을 확인할 수 있었다. 그리고 표면거칠기는 기판 bias 전압을 증가시킬수록 더 smooth 해짐을 확인하였다.인하였다.

• Journal of the Korean Chemical Society
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• v.35 no.3
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• pp.196-203
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• 1991

The $pK_a$ values of benzoic acid and meta, para-halogen substituted benzoic acids in MeOH-$H_2O$ mixtures (0∼80% of MeOH) have been determined at 25$^{\circ}$C using a conductometric method on the basis of the Fuoss-Kraus equation, and further verified using modified conductometric method of Gelb. The dependence of $pK_a$ on halogen substituents has been discussed in terms of substituent-constant (${\sigma}$), which is devided into electron-withdrawing inductive contribution (${\sigma}_1$) and electron-donating ${\pi}$-resonance one (${\sigma}_R$). The linear-dependence of ${\sigma}_1$'s on $D^{-1}$ with positive slope and that of ${\sigma}_R$'s on $D^{-1}$ with negative slope have been interpreted on the basis of field effect and through-space interaction of ${\pi}$-lone pair of halogen substituent and ionization center via ${\pi}$-system of benzene ring.