• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 추계학술대회 논문집 Vol.16
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• pp.308-312
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• 2003

The packaging of the integrated circuits requires knowledge of ceramics and metals to accommodate the fabrication of modules that are used to construct subsystems and entire systems from extremely small components. Composite ceramics ($Al_2O_3-SiO_2$) were tested for substrates. A stress analysis was conducted for a linear work-hardening metal cylinder embedded in an infinite ceramic matrix. The bond between the metal and ceramic was established at high temperature and stresses developed during cooling to room temperature. The calculations showed that the stresses depend on the mismatch in thermal expansion, the elastic properties, and the yield strength and work hardening rate of the metal. Experimental measurements of the surface stresses have also been made on a $Cu/Al_2O_3-SiO_2$ ceramic system, using an indentation technique. A comparison revealed that the calculated stresses were appreciably larger than the measured surface stresses, indicating an important difference between the bulk and surface residual stresses. However, it was also shown that porosity in the metal could plastically expand and permit substantial dilatational relaxation of the residual stresses. Conversely it was noted that pore clusters were capable of initiating ductile rupture, by means of a plastic instability, in the presence of appreciable tri-axiality. The role of ceramics for packaging of microelectronics will continue to be extremely challenging.

• 대한화학회지
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• 제20권1호
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• pp.19-34
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• 1976

Sodium sulfisoxazole hexahydrate, $C_{11}H_{12}N_3O_3SNa{\cdot}6H_2O$의 결정 및 분자구조를 X-선 회절법으로 해명하였다. 이 화합물의 결정은 공간군 $P2_1/c$에 속하는 단사형으로 a = 15.68(3), b = 7.70(2), c = $17.94(4){\AA}$, ${\beta}$ = $118(2)^{\circ}$ and Z = 4이다. Weissenberg 사진 촬영으로 얻은 회절반점의 총수는 1717개이며 중원자법을 적용하여 구조해명을 한 후 최소 자승법으로 정밀화하였으며 최종 R값은 0.14이다. Benzene ring과 isoxazole ring은 평면구조를 가지며 서로 $60^{\circ}$의 각을 이루고 있다. 나트륨 원자는 다섯개의 물의 산소 원자들과 N(1)으로 만들어진 찌그러진 팔면체로 배위되어 있다. 분자들은 결정내에서 14개의 서로 다른 종류의 수소결합으로 결합되어 있다. 여섯종류의 $O-H{\cdots}O-H$, 세종류의 $O-H{\cdots}O,$ 두종류의 $O-H{\cdots}N$및 각각 한종류의 $N-H{\cdots}O,$ $O-H{\cdots}N$, $N-H{\cdots}O-H$ 수소결합들이며 그 길이는 2.71에서 $3.04{\AA}$까지이다.

• 한국균학회지
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• 제14권2호
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• pp.101-107
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• 1986

The properties of carboxyl proteinase which was contained in Poria cocos (Schw.) Wolf were investigated by means of the purification with 0.65 ammonium sulfate saturation, DEAE cellulose and Sephadex G-75 gel filtration. This enzyme was found to hydrolyze only peptide bond between glutamyl-L-tyrosine of carbobenzoxy-L-glutamyl-L-tyrosine among the synthetic substrates of carbobenzoxy-L-glutamyl-L-tyrosine, hippuryl- L-phenylalanine and hippuryl-L-arginine. This enzyme was inhibited by $Zn^{+2},\;Fe^{+2},\;Ca^{+2},\;CN^{-1},\;P_2O_7^{-4}$ ions, but stimulated by $Hg^{+2}$ ion. Also, this enzyme was inhibited by organic compounds such as L-lysine, L-phenylalanine, hippuryl-L-phenylalanine, diazoacetyl-DL-norleucine methyl ester (DAN) and 1,2-epoxy-3-(P-nitrophenoxy)propane(EPNP). In particular, the activity was inhibited by L-lysine till 20 minutes of preincubation time rapidly, and by DAN in the presence of $Cu^{+2}$ ion more rapidly after 30 minutes than DAN in the absence of $Cu^{+2}$ ion. L-Lysine was found to be a competitive inhibitor and its $K_i$ value was determined to be 0.12 mmole by Dixon plot.

• Bulletin of the Korean Chemical Society
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• 제14권6호
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• pp.713-717
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• 1993

The crystal structure of the potassium salt of penicillin V has been studied by the X-ray crystallographic methods. Crystal data are as follows; potassium 3,3-dimethyl-7-oxo-6-phenoxyacetoamido-4-thia-1- azabicyclo[3.2.0]-heptane-2${\alpha}$-carboxylate, $K^+{\cdot}C_{16}H_{18}N_2O_5S^-$, $M_r$= 388.5, triclinic, Pl, a= 9.371 (1), b= 12.497 (2), c= 15.313 (2) ${\AA},\;{\alpha}= 93.74\;(2),\;{\beta}=99.32\;(1),\;{\gamma}=90.17\;(1)^{\circ},\;V=1765.7\;(2)\;{\AA}^3$, Z=4, $D_m=1.461\;gcm^{-1},\;{\lambda}(Cu\;K{\alpha})=1.5418\;{\AA},\;{\mu}=40.1\;cm^{-1}$, F(000)=808, T=296 K. The structure was solved by the heavy atom and difference Fourier methods with intensity data measured on an automated four-circle diffractometer. The structure was refined by the full-matrix least-squares method to a final R= 0.081 for 3563 observed $[I_0{\geq}2{\sigam}(I_0)]$ reflections. The four independent molecules assume different overall conformations with systematically different orientations of the phenyl groups although the penam moieties have the same closed conformations. There are intramolecular hydrogen bonds between the exocyclic amide nitrogen and phenoxy oxygen atoms. The penam moiety is conformationally very restricted although the carboxyl and exocyclic amide groups apparently have certain rotational degrees of freedom but the phenyl group is flexible about the ether bond despite the presence of the intramolecular N-H${\cdots}$O hydrogen bond. There are complicated pseudo symmetric relationships in the crystal lattice. The penam moieties are related by pseudo 20.5 screw axes and the phenyl groups by pseudo centers of symmetry. The potassium ions, related by both pseudo symmetries, form an infinite zigzag planar chain parallel to the b axis. Each potassium ion is coordinated to seven oxygen atoms in a severely distorted pentagonal bipyramid configuration, forming the infinite hydrophilic channels which in turn form the molecular stacks. Between these stacks, there are only lipophilic interactions involving the phenyl groups.

• Journal of Welding and Joining
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• 제18권1호
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• pp.52-58
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• 2000

Spot welding, namely a kind of electric resisting welding has been used widely in field of automobile and aircraft industries because of easiness to apply. Specimens used in this study was a mild steel of 1.2mm thickness and the electrode was a Cu-Cr alloy of 6mm diameter. The surface sheared of specimens after testing of tensile shear was observed by SEM(scanning electron microscope) after ultrasonic cleaning for 10min., and microstructures and grain size of all specimens were measured with using of O.M.(Optical microscope). By the means of measurement and observations of tensile shear load, fatigue strength and share surface, the weldability of spot welding was evaluated. When tensile shearing testing, fracture starting point in all specimens was took place at the bond between HAZ(Heat affected zone) and nugget. With increasing in number of layers, fatigue strength was decreased. With increasing in electric current, grain size in the HAZ became more fine.

• 대한화학회지
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• 제64권2호
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• pp.61-66
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• 2020

In this study, we investigate the structural and electronic properties of copper oxide clusters, Cu_nO_n (n = 9 - 15). To find the lowest energy structures of copper oxide clusters, we use ReaxFF and density functional theory calculations. We calculate many initial copper oxide clusters using ReaxFF quickly. Then we calculate the lowest energy structures of copper oxide clusters using B3LYP/LANL2DZ model chemistry. We examine the atomization energies per atom, average bond angles, Bader charges, ionization potentials, and electronic affinities of copper oxide clusters. In addition, the second difference in energies is investigated for relative energies of copper oxide clusters.

• Bulletin of the Korean Chemical Society
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• 제5권4호
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• pp.158-162
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• 1984

The crystal structure of chloramphenicol base, $C_9H_{l2}N_2O_4$, the deacylated base of antibiotic chloramphenicol, has been determined by X-ray diffraction techniques using diffractometer data obtained by the ${\omega}-2{\theta}$ scan technique with CuK${\alpha}$ radiation from a crystal with space group symmetry $P2_12_12_1$ and unit cell parameters a = 22.322(6), b = 7.535(6), c = 5.781(5) ${\AA}$. The structure was solved by direct methods and refined by full-matrix least-squares to a final R = 0.051 for the 573 observed reflections. The overall conformation of the base is quite different from those of the chloramphenicol congeners which are similar despite the presence of many rotatable single bonds. The propane chain in the base is bent with respect to the phenyl ring, while it is extended in the chloramphenicol congeners. There is no intramolecular hydrogen bond between the hydroxyl groups of the propanediol moiety. All of the molecules in the crystal lattice are connected by a three-dimensional hydrogen bonding network.

• 대한화학회지
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• 제38권4호
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• pp.295-301
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• 1994

N4-polydentate 리간드(meso-Me$_6$-[14]-ane, rac-Me$_6$-[14]-ane, and cyclam)의 Ru(Ⅲ), Ni(Ⅱ), Cu(Ⅱ) 및 Pd(Ⅱ)금속이온 착물을 합성하여 NaOCl, H$_2$O$_2$, t-BuOOH, 및 PhIO 등의 산화제를 사용하므로서 몇 가지 올레핀 산화반응에서 각 착물의 촉매적 활성과 선택성을 연구하였다. substrate(cyclohexene, 1-hexene, cyclooctene, 1-octene, 및 styrene)의 산화반응 생성물질은 가스 크로마토그래프 방법으로 확인하였다. Ru(Ⅲ)-N$_4$ 착물은 올레핀의 촉매적 산화반응에서 산화제로 NaOCl을 사용하였을 때, 생성물질 epoxide에 대하여 상당히 높은 선택성을 나타내었다. Ru(Ⅲ)-N$_4$ 착물의 촉매적 활성도는 N$_6$-polydentate리간드의 flexibility, Ru(Ⅲ)-Cl의 결합 상호작용, 및 산화제의 입체적 효과에 따라 고찰하였다. Ni(II)-, Cu(II)-, 및 Pd(II)- (meso-Me$_6$[14]-ane) 착물의 촉매적 기능은 산화제로 PhIO를 사용한 1-octane의 산화반응에서 살펴 보았으며, 이 산화반응에서 Pd(Ⅱ)착물이 Ni(Ⅱ) 및 Cu(Ⅱ)착물들보다 높은 활성을 나타내었다.

• 대한화학회지
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• 제24권3호
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• pp.193-200
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• 1980

N-Acetyl-L-cysteine, $C_5H_9NO_3S,$의 결정 및 분자구조를 X-선 회절법으로 연구하였다. 이 화합물의 결정은 삼사비등축정계에 속하며 공간군은 $P_1$이다. 단위세포상수는 a = 7.04(3), b = 5.14(2), c = 8.25(3)${\AA}$, ${\alpha}$ = 106(2), ${\beta}$ = 51(1), ${\gamma}$ = 124(2)$^{\circ}$이고, 단위세포는 분자 한개만을 포함하고 있다. Weissenberg 사진촬영으로 얻은 회절반점의 총수는 629개이며 direct method를 적용하여 구조해명을 한 후 full matrix least-squares method로 정밀화하였으며 최종 R값은 0.12이다. C-카르복실기 및 N-아세틸기의 원자들은 각각 평면을 이루고 있다. 카르복실기의 산소원자 O(1)은 이웃분자의 아세틸기의 산소원자 O(3)와 $O-H{\cdot}{\cdot}{\cdot}O$ 수소결합을 하며 그 길이는 2.59${\AA}$이다.

• 대한화학회지
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• 제21권1호
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• pp.3-15
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• 1977

Salicylaldehyde-4-morpholinothiosemicarbazone, $C_{12}H_{15}O_2N_3S$, 결정은 직각비등축정계에 속하며 공간군은 $Pna2_1$이다. 단위세포에는 4개의 분자가 포함되면 세포 길이는 a = 11.85(5), b = 15.45(5), c = 7.18(3)${\AA}$이다. 농도는 multiple-film equi-inclination Weissenberg 사진으로부터 3차원적 농도 데이타를 얻어 목측법에 의하여 측정하였다. 결정구조는 Patterson 및 Fourier법으로 해명하였으며 구조의 정밀화는 block-diagonal 최소자승법으로 하였으며 R값은 1064개의 반사에 대하여 0.11이었다. 몰포린 고리는 의자형이며 1분자내의 몰포린 고리와 황원자를 제외한 원자들은 대략 한 평면을 이룬다. 수산화기의 산소원자는 질소원자와 2.67${\AA}$의 거리로 $O-H{\cdot}{\cdot}{\cdot}N$형 수소결합을 하고 있고 분자간에는 van der Waals 접촉으로 연결되어 있다.