• 대한화학회지
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• 제16권2호
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• pp.59-63
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• 1972

In connection with two electron binding energy of each bond of saturated hydrocarbons, C-C bond fission and hydrogen abstraction from C-H bond are discussed by means of two center Huckel method. A beautiful correlation could be noticed between the observed bond dissociation energy and the calculated bond energy except for n-butane. Bond dissociation energies between C-C bond were also related to C-C bond fission. We could also find a very close relation between the relative easiness of hydrogen abstraction and the calculated binding energy of C-H bond. In other words, C-H bonds of tertiary hydrogen have been noticed as most weakely bonded and hence the tertiary hydrogen would most easily from the paraffins. In addition, the C-H binding energy is discussed applying ionic character of C-H bond which is derived from its dipole moment (0.4D)

• Journal of Welding and Joining
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• 제15권5호
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• pp.104-114
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• 1997

The microstructure and bond strength were investigated on the SiC/SiC and SiC/mild steel joints brazed by Ag-5at%Ti alloy. Ag-5at%Ti-2at%Fe and -5at%Fe brazing alloys were also used to see the effects of Fe addition on the bond strength of SiC/SiC brazed joints. Brazing temperature and brazing gap were selected and examined as brazing variables. The microstructure of SiC/SiC brazed joints was affected by Fe addition to the Ag-5at%Ti alloy, but the bond strength was not. Increasing brazing temperature also changed the microstructure of $Ti_5Si_3$ reaction layer and brazing alloy matrix of the SiC/SiC and SiC/mild steel joints, but not the bond strength. Brazing gap had a great effects on the bond strength. Decreasing brazing gap from 0.2 mm to 0.1 mm in SiC/SiC brazing increased the bond strength from 187 MPa to 263 MPa and, in SiC/mild steel brazing, from 189 MPa to 212 MPa. It was concluded that the most important parameter on the bond strength in SiC/SiC and SiC/mild steel brazing was the relative ratio between brazing gap and specimen size.

• Journal of Welding and Joining
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• 제14권4호
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• pp.99-108
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• 1996

The microstructure and bond strength are examined on the SiC/SiC and SiC/mild steel joints brazed by the Ag-Ti based alloys with different Ti contents. In the SiC/SiC brazed joints, the thickness of the reaction layers at the bond interface and the Ti particles in the brazing alloy matrices increase with Ti contents. When Ti is added up to 9 at% in the brazing alloy. $Ti_3SiC_2$ phase in addition to TiC and $Ti_5Si_3$ phase is newly created at the bond interface and TiAg phase is produced from peritectic reaction in the brazing alloy matrix. In the SiC/mild steel joints brazed with different Ti contents, the microstructure at the bond interface and in the brazing alloy matrix near SiC varies similarly to the case of SiC/SiC brazed joints. But, in the brazing alloy matrix near the mild steel, Fe-Ti intermetallic compounds are produced and increased with Ti contents. The bond strengths of the SiC/SiC and SiC/mild steel brazed joints are independent on Ti contents in the brazing alloy. There are no large differences of the bond strength between SiC/SiC and SiC/mild steel brazed joints. In the SiC/mild steel brazed joints, Fe dissolved from the mild steel does not affect on the bond strength of the joints. Thermal contraction of the mild steel has nearly no effects on the bond strength due to the wide brazing gap of specimens used in the four-point bend test. The brazed joints has the average bond strength of about 200 MPa independently on Ti contents, Fe dissolution and joint type. Fracture in four-point bend test initiates at the interface between SiC and TiC reaction layer and propagates through SiC bulk. The adhesive strength between SiC and TiC reaction layer seems to mainly control the bond strength of the brazed joints.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2006년도 추계학술대회 논문집 Vol.19
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• pp.170-171
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• 2006

The chemical shift of SiOC film was observed according to the flow rate ratio. SiOC film has the broad main band of $880{\sim}1190cm^{-1}$ and the sharp Si-$CH_3$ bond at $1252cm^{-1}$, and the infrared spectra in the Si-O-C bond moved to low frequency according to the increasing of an oxygen flow rate. The chemical shift affected the carbon content in the SiOC film, and the decreasing of carbon atoms elongated the C-H bonding length, relatively. The main bond without the sharp Si-$CH_3$ bond at $1252cm^{-1}$ consisted of Si-C, C-O and Si-O bonds, and became the bonding structure of the Si-O-C bond.

• 대한화학회지
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• 제20권2호
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• pp.111-117
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• 1976

Methyl benzamidoxime의 C=N 결합에 의한 configuration 과 N-O 및 C-N 결합에 대한 conformation 에 관하여 확장 Huckel 분자궤도법 계산을 실시하였다. 계산 결과는 C-N 결합의 conformation이 sp-형이면 E-configuration이 Z-configuration보다 더 안정하다. ap-형이면 Z-configuration이 더 안정하다. C=N 결합의 configuration과 C-N 의 conformation이 같으면 N-O의 conformation이 ap-형인 것이 더 안정하다. 이 안정화 에너지의 대부분은 정전기적인 원자간에 힘에 기인하는 것임을 밝혔다.

• 대한치과보철학회지
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• 제33권4호
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• pp.662-684
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• 1995

The purpose of this study was to evaluate the shear bond strength between various resin-bonded retainers and enamel according to the adhesive resins and retention types and observe the bond filure modes with scanning electron microscope(SEM). For this purpose, the followin eight sub-groups were tested in shear bond strength : 1) electrochemically etched group(Verabond) using Panavia EX and Superbond C&B 2) tin-plated group(PG-S) using Panavia EX and Superbond C&B 3) salt-treated group(Verabond) using Panavia EX and Superbond C&B 4) meshtreated group(Verabond) using Panavia EX and Superbond C&B. Thermocycling test was conducted on the condition of 15 second dwell time each in $5^{\circ}C$ and $55^{\circ}C$bath. Shear bond strength was measured by Instron Universal Testing Machine(medel 1125). The obtained results were as follows : 1. After thermocycling, the shear bond strengths of tin-plated group and electrochemically etched group were significantly greater than those of salt-treated group and mesh-treated group. And the shear bond strength of Panavia EX was greater than that of Superbond C&B with salt-treated group and tin-plated group(p<0.05). 2. Before thermocycling, electrochemically etched group using Superbond C&B produced the greatest shear bond strength(p<0.01). 3. The shear bond strength of electrochemically etched group using Superbond C&B was significantly decreased after thermocycling(p<0.01). 4. In observation of bond failure modes before thermocycling, Panavia EX highly exhibited enamel fracture. Tin-plated group using Superbond C&B adhesive failure between metal and resin and electrochemically etched group using Superbond C&B exhibited adhesive failure between enamel and rdsin. 5. In observation of failure modes after thermocycling, Panavia EX exhibited cohesive failure and Superbond C&B exhibited adhesive failure between resin and metal.

• 대한화학회지
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• 제38권2호
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• pp.169-173
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• 1994

인도네시아 Manado만의 Sulawesi에서 채집한 미동정된 해면으로부터 KB cancer cell line에 대해 활성을 갖는 xestoquinone, halenaquinol sulfate 및 halenaquinol이 검출되었다. 이들을 $^1H-,\;^{13}C$-NMR, $^1H-,\;^{13}C$(1 bond) heteronuclear Multiple Quantum Cogerence Spectroscopy$(HMQC)^1$, $^1H-,\;^{13}C$C(2 and 3 bond) Heteronuclear multiple Bond Correlation Spectroscopy$(HMBC)^2$, Electron Impact Mass Spectroscopy(EI ms), UV 및 IR에 의해 밝혔다.

• Bulletin of the Korean Chemical Society
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• 제25권11호
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• pp.1623-1624
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• 2004

• 반도체디스플레이기술학회지
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• 제7권3호
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• pp.1-4
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• 2008

The chemical shift of SiOC film was observed according to the flow rate ratio. SiOC film had the broad main band of $880\sim1190cm^{-1}$ and the sharp Si-$CH_3$ bond at $1252cm^{-1}$, and the peak position of the main bond in the infrared spectra moved to high frequency according to the increasing of an BTMSM flow rate. So the increment of the alkyl group induced the C-H bond condensation in the film, and shows the blueshift in the infrared spectra. In the case of P5000 system of Applied Materials Corporation, the strong bond of Si-CH3 bond in precursor does not enough to dissociated and ionized, because low plasma energy due to the capactive coupled CVD. Therefore, there was the sharp peak of Si-$CH_3$ bond at $1252cm^{-1}$.

• 대한화학회지
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• 제39권4호
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• pp.301-305
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• 1995

인도네시아 Manado만의 Sulawesi에서 채집한 해면 Spongia sp.로부터 KB Cancer cell line에 대하여 활성을 갖는 halenaquinone, epispongiatriol 및 aldisin을 분리하였다. 이들의 구조를 $1^H,\;13^C\;NMR\;1^H\;13^C(1\;bond)$ Heteronuclear Multiple Quantum Coherence Spectroscopy (HMQC), 1H 13C(2 and 3 bond) Heteronuclear Multiple Bond Correlation Spectroscopy (HMBC), Electron Impact Mass Spectroscopy (EI ms) 및 IR로 밝혔다.