• 대한화학회지
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• 제44권6호
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• pp.518-525
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• 2000

열린 고리 형태의 질소-산소계 여섯 자리 리간드 1,13-bis(2-hydroxybenzyl)-2,5,9,12-tetraazatridecane-tetrahydrochloride(BSATD${\cdot}$4HCl)와 1,14-bis(2-hydroxybenzyl)-2,6,9,12-tetraazatetradecanetetrahydrochloride(BSATED${\cdot}$4HCl)을 네 개의 염산염으로 합성하여 원소분석, 적외선 분광법, 핵 자기 공명법 및 질량스펙트럼으로 합성을 확인하였다. 합성된 리간드들의 산 해리상수값(log$K^{n}_{H}$)과 Cu(II), Ni(II), Co(II) 및 Zn(II)에 대한 안정도 상수 값 (log$K_{ML}$)을 전위차 적정법으로 구하고, 지방족 아민의 질소 원자들 사이에 에틸렌기와 프로필기를 포함하는 리간드들의 고리길이 효과에 따른 산 해리상수 특성 및 전이금속에 대한 안정도상수값에 미치는 영향을 고찰하였다. 그리고 $[Cu(BSATD)]ClO_4$ 와 $[Cu(BSATED)](ClO_4)_2$구리(II)착물을 합성하여 그 성질을 알아보았다.

• Bulletin of the Korean Chemical Society
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• 제30권12호
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• pp.2962-2968
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• 2009

The photodissociation dynamics of 1,2-bromochloroethane ($C_2H_4BrCl$) was investigated near 234 nm. A two-dimensional photofragment ion-imaging technique coupled with a [2+1] resonance-enhanced multiphoton ionization scheme was utilized to obtain speed and angular distributions of the nascent Br($^2P_{3/2}$) and Br${\ast}($^2P_{1/2}$) atoms. The total translational energy distributions for the Br and Br${\ast}$ channels were well characterized by Gaussian functions with average translational energies of 100 and 84 kJ/mol, respectively. The recoil anisotropies for the Br and Br${\ast}$ channels were measured to be ${\beta}$ = 0.49 ${\pm}$ 0.05 for Br and 1.55 ${\pm}$ 0.05 for Br${\ast}$. The relative quantum yield for Br${\ast}$ was found to be ${\Phi}_{Br{\ast}}$ = 0.33 ${\pm}$ 0.03. The probability of nonadiabatic transition between A' states was estimated to be 0.46. The relevant nonadiabatic dynamics is discussed in terms of interaction between potential energy surfaces in Cs symmetry.

• 폴리머
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• 제37권1호
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• pp.94-99
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• 2013

폴리디아세틸렌(polydiacetylene, PDA)은 자기조립된 디아세틸렌(diacetylene) 단량체의 광중합에 의해 만들어진다. 디아세틸렌 단량체들이 조직적으로 배열되면 254 nm의 자외선 노광에 의해 1,4-첨가 중합이 일어나 고분자 주사슬에 이중결합과 삼중결합이 교대로 존재하는 폴리디아세틸렌이 만들어진다. 폴리디아세틸렌 수용액은 일반적으로 약 640 nm에서 최대흡수파장을 지니는 청색을 띠게 되며 여기에 온도나 pH의 변화, 다른 물질의 결합 등 외부 자극에 의해 약 550 nm의 최대 흡수 파장을 띠는 적색으로 색 전이가 일어나게 된다. 본 연구에서, 우리는 고체상 펩티드 합성을 이용하여 PCDA(10,12-pentacosadyinoic acid) 리포좀의 표면에 양이온성 올리고펩티드를 도입하였다. 또한 다양한 몰 비율로 리포좀 수용액을 제조하여 동물 세포에 트랜스펙션한 결과, 향상된 유전자 전달 효율과 낮은 독성을 보이는 것을 확인하였고, PCDA의 특성을 이용하여 세포에 처리 후 세포 관련 비표지 형광을 관찰하였다.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2009년도 제38회 동계학술대회 초록집
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• pp.435-435
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• 2010

A inclined slot-excited plasma source is newly designed and constructed for higher flux HNB(Hyperthermal Neutral Beam) generation. The present source is different from the vertical SLAN(SLot ANtenna) sources [1] in two aspects. One is that the slots are inclined, and the other is that the magnetic field is configured to a cusp type. These modifications are intended to make the source plasma operated in sub-milli-torr pressure regime and as thin as possible, both of which is to get higher HNB flux by decreasing the re-ionization rate of the reflected atoms from the neutralizer [2]. The plasma is generated in a quartz tube of internal diameter 170 mm enclosed in a aluminum application chamber of larger diameter 250 mm. The microwave power is fed to the plasma chamber by 8 inclined slots cut into the application chamber wall. The slots are coupled the chamber to a WR280 waveguide wound around it to form a ring resonator. In order to make two slots $\lambda_g/2$ apart in phase, the adjacent slots are rotated in opposite directions. The rotation angle of the slots are set to $60^{\circ}$ from the chamber axis. Between the quartz chamber and the aluminum cylindrical chamber 8 NdFeB magnets are equally spaced and fixed to form the cusp magnetic field confinement and ECR (Electron Cyclotron Resonance) field. In this presentation, the magnetic and electromagnetic simulations, and the measured plasma parameters are given for both the inclined and the vertical slot-excited plasma sources. We also discuss how the sources can be tailored to suit better-performing HNB sources.

• Journal of Welding and Joining
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• 제1권2호
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• pp.45-52
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• 1983

Many pressure vessels for the hot H$\sub$2//H$\sub$2/S service are made of 2+1/4Cr-1Mo steel with austenitic stainless steel overlay to combat agressive corrosion due to hydrogen sulfide. Hydrogen dissolves in to materials during operation, and sometimes gives rise to unfore-seeable damages. Appropriate precautions must, therefore, be taken to avoid the hydrogen induced damages in the design, fabrication and operation stage of such reactor vessels. Recently, hydrogeninduced cracking (or Disbonding) was found at the interface between base metal and stainless weld overlay of a desulfurizing reactor. Since the stainless steel overlay weld metal is subjected to thermal and internal-pressure loads in reactor operation, it is desirable for the overlay weld metal to have high strength and ductility from the stand point of structural safety. In section III of ASME Boiler and Pressure Vessel Code, Post-Weld Heat Treatment(PWHT) of more than one hour per inch at over 1100.deg. F(593.deg. C) is required for the weld joints of low alloy pressure vessel steels. This heat treatment to relieve stresses in the welded joint during construction of the pressure vessel is considered to cause sensitization of the overlay weld metal. The present study was carried out to make clear the diffusion of carbon migration by PWHT in dissimilar metal welded joint. The main conclusion reached from this study are as follows: 1) The theoretical analysis for diffusion of carbon in stainless steel overlay weld metal does not agree with Fick's 2nd law but the general law of molecular diffusion phenomenon by thermodynamic chemical potential. 2) In the stainless steel overlay welded joint, the PWHT at 720.deg. C for 10 hours causes a diffusion of carbon atoms from ferritic steel into austenitic steel according to the theoretical analysis for carbon migration and its experiment. 3) In case of PWHT at 720.deg. C for 10 hours, the micro-hardness of stainless steel weld metal in bonded zone increase very highly in the carburized layer with remarkable hardening than that of weld metal.

• 열처리공학회지
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• 제4권2호
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• pp.19-26
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• 1991

강의 내마모성과 내식성을 증가시키기 위하여 종래의 방법보다 우수한 확산표면경화처리에 대하여 연구하였다. 무수붕사($Na_2B_4O_7$)를 주체로 하는 해당염욕에 첨가물로서 -100 mesh의 Fe-V를 첨가한 후 각각 탄소량을 달리하는 시편을 침적시켜 탄화물층의 형성유무와 탄화물층과 침척시간과의 관계 및 피처리재중의 탄소량과의 관계에 대하여 조사하였고, 탄화물층내의 미소경도를 측정하였다. 연구결과는 다음과 같다. (1) 탄화물층은 모재표면의 C원자와 붕사욕 중에 용출된 V와 결합에 의해서 형성되고 형성된 탄화물층 속으로 확산해서 모재 중의 C원자가 표면에 보급되는 것에 의해서 성장한다. (2) 탄화물층의 두께는 온도와 탄소량이 일정할 경우 침척시간의 1/2 승에 비례하였다. 또한 온도와 침적시간이 일정할 경우 탄소량이 증가할수록 탄화물층의 두께는 증가하였다. (3) 시편의 표면에 형성된 탄화물층은 VC층이었으며, 이 탄화물층 내의 미소경도는 $H_v$ 3,000 이상이다.

• 한국산학기술학회논문지
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• 제11권11호
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• pp.4468-4472
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• 2010

ICP-CVD 방법에 의해 제작된 SiOC 박막을 유전상수와 화학적 이동의 상관성에 대하여 조사하였다. SiOC 박막은 플라즈마 에너지에 의해서 해리작용과 재결합작용에 의해서 cross link 구조를 갖게 되는 Si-O 와 C-O 결합으로 구성된 $930{\sim}1230\;cm^{-1}$ 영역에서 혼합된 Si-O-C 주 결합으로 이루어졌다. C-O 결합은 $1270cm^{-1}$에서 보여지는 Si-$CH_3$ 결합의 말단부분인 C-H 결합이 전기음성도가 큰 산소에 의해서 끌리는 효과로부터 만들어진 결합이다. 그러나 Si-O 결합은 Si-$CH_3$ 결합이 분해되고 난뒤 2차 이온결합에 의해서 만들어진 결합이다. Si-O 결합의 증가는 주결합에서 오른쪽 결합이 증가하기 때문이며, FTIR 스펙트라에 의해서 red shift로 나타났다. 이러한 결과는 SiOC 박막이 보다 더 안정되고 강한 박막임을 의미한다. 그래서 SiOC 박막은 열처리 후 비정질도가 높고 거칠기가 감소되는 것을 확인하였다.

• 한국응용과학기술학회지
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• 제8권2호
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• pp.105-114
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• 1991

In relation to the preparation of Langmuir-Blodgett thin film, four kinds of N-alkylpyridiniurn bromide were synthesized. The values of surface tensions of these materials, measured with a Traube stalagmometer, gave the relationship between the critical micells hydrophobic radical and between CMC and temperature. Values of thermodynamic properties(${\Delta}H^0_m,\;{\Delta}S^0_m,\;{\Delta}G^0_m,$) for the formatoin of micelle were also obtained. Experiments gave the following results; at the temperature range between 40 and 60$^{\circ}C, CMC of Hexadecyl-, Octadecyl-, Eicosyl-, and Docosyl-Pyridinium Bromide were $7.64{\times}10^{-4}{\sim}9.13{\times}10^{-4},\;3.85{\times}10^{-4}{\sim}4.60{\times}10^{-4},\;2.00{\times}10^{-4}{\sim}2.39{\times}10^{-4},\;and\;1.07{\times}10^{-4}{\sim}1.28{\times}10^{-4}$ mol/l, respectively. Surface tension, ${\Gamma}_{CMC}$, of those were 33.49${\sim}$36.00, 34.78${\sim}$37.61, 35.49${\sim}$37.61 and 38.76${\sim}$55.80 dyne/cm, respectively, The relationship between CMC and the mumber of carbon atoms in the hydrophobic radical, N was expressed as follows : Log(CMC)=A-BN where A and B are constants. At the temperature range between 40 and 60$^{\circ}C$, the change of Gibbs evergy (${\Delta}G_m$) for one methylene group ($-CH_2-$) were -0.65RT, respectively, The minus values of enthalpy change (${\Delta}H_m$) suggest that the formation of micelle is exothermic. Additionally, the overall increase in the entropy change (${\Delta}S_m$) with respect to the temperature increase suggests that the formation of micelle is attained by a exothermic enthalpy directed process.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.145-145
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• 2010

In this paper, we report that the effects of hydrogen doping on the electrical and optical properties of typical transparent conducting oxide films such as ZnO and $SnO_2$ prepared by magnetron sputtering. Recently, density functional theory (DFT) calculations have shown strong evidence that hydrogen acts as a source of n-type conductivity in ZnO. In this work, the beneficial effect of hydrogen incorporation on Ga-doped ZnO thin films was demonstrated. It was found that hydrogen doping results a noticeable improvement of the conductivity mainly due to the increases in carrier concentration. Extent of the improvement was found to be quite dependent on the deposition temperature. A low resistivity of $4.0{\times}10^{-4}\;{\Omega}{\cdot}cm$ was obtained for the film grown at $160^{\circ}C$ with $H_2$ 10% in sputtering gas. However, the beneficial effect of hydrogen doping was not observed for the films deposited at $270^{\circ}C$. Variations of the electrical transport properties upon vacuum annealing showed that the difference is attributed to the thermal stability of interstitial hydrogen atoms in the films. Theoretical calculations also suggested that hydrogen forms a shallow-donor state in $SnO_2$, even though no experimental determination has yet been performed. We prepared undoped $SnO_2$ thin films by RF magnetron sputtering under various hydrogen contents in sputtering ambient and then exposed them to H-plasma. Our results clearly showed that the hydrogen incorporation in $SnO_2$ leads to the increase in carrier concentration. Our experimental observation supports the fact that hydrogen acting as a shallow donor seems to be a general feature of the TCOs.

• 한국초전도ㆍ저온공학회논문지
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• 제21권3호
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• pp.13-17
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• 2019

We investigate the effect of thermal annealing on $MgB_2$ thin films with thicknesses of 400 and 800 nm, irradiated by 350 keV C-ions with a dose of $1{\times}10^{15}atoms/cm^2$. Irradiation by low-energy C-ions produces atomic lattice displacement in $MgB_2$ thin films, improving magnetic field performance of critical current density ($J_c$) while reducing the superconducting transition temperature ($T_c$). Interestingly, the lattice displacement and the $T_c$ are gradually restored to the original values with increasing thermal annealing temperature. In addition, the magnetic field dependence of $J_c$ also returns to that of the pristine state together with the restoration of $T_c$. Because $J_c$(H) is sensitive to the type and density of the disorder, i.e. vortex pinning, the recovery of $J_c$(H) in irradiated $MgB_2$ thin films by thermal annealing indicates that low-energy C-ion irradiation on $MgB_2$ thin films primarily causes lattice displacement. These results provide new insights into the application of low-energy irradiation in strategically engineering critical properties of superconductors.