• 대한화학회지
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• 제19권4호
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• pp.233-239
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• 1975

세개의 二重結合에 衣하여 conjugate된 비대칭화합물 cis-2-bitenedialdioxime의 두 oxime group의 configuration을 溶媒, 溫度 및 濃度의 影響에 대한 NMR 硏究로서 決定하였다. 溶液狀態에서의 이 化合物은 $-35^{circ}$∼$-95^{\circ}C$의 溫度條件下에서는 항상 "syn-syn" configuration으로 存在함을 알았다. 또한 이 化合物의 oxime group과 溶媒사이의 水素結合의 相對的强度와 溫度 및 濃度에 의 피리딘의 考察하고 몇가지 水素結合의 모델을 提示하였다. 特히 피리딘溶媒 속에서는 水素結合은 한 영향을 窒素가 갖고 있는 非共有電子雙에 衣해서 일어나지 않고, oxime 의 hydroxyl proton과 피리딘의 $\pi$軌道函數 사이에 形成되는 $\pi$-착물의 結果임을 알았다.

• Journal of the Korean Wood Science and Technology
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• 제39권6호
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• pp.498-504
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• 2011

The purpose of this study was to investigate and develop an eco-frendly wood adhesive based on vegetable oil (especially soybean oil), the renewable and sustainable natural resources, using ozonification technology for the chemical structure modification. The waste soybean oil (WSBO) was reacted with $O_3$ at the rate of $450m{\ell}$(acetone) : $50m{\ell}$ (WSBO) for different times, 1, 2, 3 hrs. The investigation of the modified chemical strecture of the ozonied WSBOs were conducted using FT-IR. As ozonification time increased, the peak of the unsaturated double bonds was disappeared especially ozonized-3hrs and aldehyde or carboxyl peak appeared because ozonification broke the oil into small molecules. The plywood were made at $150^{\circ}C$ with 4 minutes hot-press time using the different ozonized 3 hrs WSBO/pMDI adhesives and were tested for the dry, wet, cyclic boil test according to the Korea Industrial Standard F3101 Ordinary plywood. The bond strengths gradually increased until 1 : 0.5~1 : 3, but it decreased 1 : 4, as the contents of pMDI increased. The results of the dry, wet and cyclic bond strengths the equivalent ratio was formed approximately between 1 : 2~1 : 3. And the 1 : 1~1 : 4 strengths met constantly the standard requirement of 7.0kgf/$cm^2$ (KS F3101). From the comprehensive view on the results of above experiment, it could be confirmed that ozonized WSBO/pMDI has characteristics of effective reactivity and wet stability showed as an excellent candidate of wood adhesive applications.

• 한국식품과학회지
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• 제36권3호
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• pp.398-402
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• 2004

신소재로 각광 받고 있는 chitosan의 낮은 수용성을 극복하기 위하여 chitosan 유도체인 safrolechitosan(SaCs) 및 eugenolchitosan(EuCs)을 제조하고, Ubbelohde 점도계를 사용하여 이들의 점도평균분자량을 측정한 결과, chitosan 및 chitosan유도체인 EuCs와 SaCs의 경우 각각 $1.2{\times}10^{5}\;Da,\;7.8{\times}10^{5}\;Da$ 및 $7.5{\times}10^{5}\;Da$인 것으로 확인되었다. Chitosan과 chitosan유도체의 구조분석을 위한 IR spectrum에서 SaCs의 경우, safrole의 공유결합에 의한 chitosan내 amine기와의 반응으로 인하여 순수 chitosau보다 amide II 흡수띠가 $1,553cm^{-1}$으로 이동함을 알 수 있었는데, 이것은 chitosan내의 1차 amine기와 safrole의 이중결합이 반응하여 공유결합을 형성함으로써 흡수띠의 이동현상이 나타난 결과이다. 또한, safrole이 반응하면서 safrole내의 vinyl기를 의미하는 특징적인 peak인 C=C 및 $H_{2}C=$의 $1,611cm^{-1}$와 $1,442cm^{-1}$에서의 흡수띠가 사라졌으며, EuCs의 경우에도 반응물질로 사용된 eugenol내의 vinyl기를 나타내는 $1,612cm^{-1}$ 및 $1,434cm^{-1}$에서의 흡수띠가 사라짐을 확인하였다. 또한 $^{1}H-NMR\;spectrum$을 확인한 결과, 합성유도체의 경우 safrole과 eugenol 간량체의 5.7-6.0ppm에서 나타난 이중결합($H_{2}C=CH-$) peak가 사라지고, SaCs는 2.1-2.2ppm에서, 그리고 EuCs는 1.9와 2.2ppm에서 단일결합($-CH_{2}-CH_{2}-$)의 peak가 생성됨을 알 수 있었으며, safrole과 eugenol이 chitosan에 그라프트된 후 safrole과 eugenol의 영향으로 chitosan내의 $H_{3}-H_{6}$의 수소 숫자가 상대적으로 감소하여 3.1-3.9ppm에서 나타나는 peak의 크기가 작아짐도 확인하였다. 이상의 결과들을 종합해 볼때, SaCs 및 EuCs를 합성하기 위한 그라프트 반응이 정상적으로 일어났음을 알 수 있었다.

• Nuclear Engineering and Technology
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• 제54권12호
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• pp.4514-4521
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• 2022

In this study, the effects of heat and radiation on the degradation behaviour of fluoroelastomer under simulated normal operation and a severe accident environment were investigated using sequential testing of gamma irradiation and thermal degradation. Tensile properties and Shore A hardness were measured, and thermogravimetric analysis was used to evaluate the degradation behaviour of fluoroelastomer. Fourier transform infrared spectroscopy and X-ray photoelectron spectroscopy were used to characterize the structural changes of the fluoroelastomer. Heat and radiation generated in nuclear power plant break and deform the chemical bonds, and fluoroelastomer exposed to these environments have decreased C-H and functional groups that contain oxygen and double bonds such as C-O, C=O and C=C were generated. These functional groups were formed by auto oxidation by reacting free radicals generated from the cleaved bond with oxygen in the atmosphere. In this auto oxidation reaction, crosslinks were generated where bonded to each other, and the mobility of molecules was decreased, and as a result, the fluoroelastomer was hardened. This hardening behaviour occurred more significantly in the severe accident environment than in the normal operation condition, and it was found that thermal stability decreased with the generation of unstable structures by crosslinking.

• 한국신뢰성학회지:신뢰성응용연구
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• 제15권3호
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• pp.197-206
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• 2015

Failure analysis of pre-insulated pipe (SPPS 380, 400A) transporting high temperature water ($95{\sim}110^{\circ}C$) for a plant was carried out. The damaged area (${\Phi}5mm$) of pre-insulated pipe was found only on welds. The chemical composition of damaged pipe meets specification of carbon steel pipes for pressure service (KS D 3562). As results of microstructure analysis, crack propagated from outer to inside after pitting corrosion occurred on the outside surface. The non-metallic inclusion existed on the end of crack. And the non-metallic inclusion continuously and linearly formed along with the bond line of welds. Based on SEM-EDS analysis, the nonmetallic inclusions have higher Manganese (Mn) and Oxygen (O) content but sulfur (S) was not detected. As results of water quality analysis, hydrogen ion concentration and minerals like Fe, Mg, Si were in low level. But the content of dissolved oxygen (11.2 ppm) was slightly higher than that of standard. It seems that the cause of damaged pipe is grooving corrosion due to MnO inclusion formed on bond line and corrosion took place nearby welds.

• 대한화학회지
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• 제40권7호
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• pp.483-491
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• 1996

Cyclopentadiene과 exo-cyclic 이중결합을 가진 5각고리 화합물간의 Diels-Alder반응을 PM3 방법을 이용하여 연구하였다. Dienophile의 종류가 바뀌어도 전이상태의 구조는 커다란 변화를 나타내지 않았다. 반면에 dienophile의 exocyclic C(=O)-R 결합의 회w전에 의하여 나타나는 두 conformer들은 서로 다른 생성물을 얻을 수 있었으며, 이들의 반응성을 FMO들의 energy gap을 이용하여 설명하였다. 반면에 dienophile의 접근방향에 따른 exo, endo경로의 선택성을 살펴보기 위하여 전이상태에서의 deformation enerhy와 활성와 에너지간의 상관관계를 살펴보았다. 반응의 최저 에너지 경로를 Curtin-Hammett principle을 사용하여 논의 하였다.

• Elastomers and Composites
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• 제54권2호
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• pp.110-117
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• 2019

The characterization of the ozone oxidation for raw natural rubber (NR) was investigated under controlled conditions through image and fourier transform infrared (FT-IR) analysis. The ozone oxidation was performed on a transparent thin film of raw NR coated on a KBr window in a dark chamber at $40^{\circ}C$ under low humidity conditions to completely exclude thermal, moisture, or light oxidation. The ozone concentration was set at 40 parts per hundred million (pphm). Before or after exposure to ozone, the image of the thin film for raw NR was observed at a right or tilted angle. FT-IR absorption spectra were measured in the transmission mode according to ozone exposure time. The ozone oxidation of NR was determined by the changes in the absorption peaks at 1736, 1715, 1697, and $833cm^{-1}$, which were assigned to an aldehyde group (-CHO), a ketone group (-COR), an inter-hydrogen bond between carbonyl group (-C=O) from an aldehyde or a ketone and an amide group (-CONH-) of protein, and a cis-methine group ($is-CCH_3=CH-$, respectively. During ozone exposure period, the results indicated that the formation of the carbonyl group of aldehyde or ketone was directly related to the decrement of the double bond of cis-1,4-polyisoprene. Only carbonyl compounds such as aldehydes or ketones seemed to be formed through chain scission by ozone. Long thin cracks with one orientation at regular intervals, which resulted in consecutive chain scission, were observed by image analysis. Therefore, one possible two-step mechanism for the formation of aldehyde and ketone was suggested.

• 한국응용과학기술학회지
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• 제9권2호
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• pp.149-156
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• 1992

Levels of total lipids in the seeds of three species of the Pinaceae family were determined and their fatty acid compositions were also analyzed by a gas-chromatograph equipped with a capillary column coated with Carbowax 20M. The results are summarized as follows: Lipid contents of the seeds amounted to 56.9% in P. koraiensis, 29.9% in P. thunbergii, and 21.2% in P. rigida. In all lipids 19${\sim}$20 fatty acid were detected and, surprisingly, fatty acids having ${\Delta}^5$-non-methylene interrupted conjugate double bond such as ${\Delta}^{5, 9}-C_{18:2},{\Delta}^{5, 9, 12}-C_{18:3}\;and\;{\Delta}^{5, 11, 14}-C_{20:3}$ occurred in appreciable amounts. In the lipids of P. koraiensis, the main component was $C_{18:2}{\omega}_6(45.0%)$, followed by $C_18:1{\omega} _9(26.9%)$ and ${\Delta}^{5, 9, 12}-C_{18:3}(14.6%)$, and then ${\Delta}^{5, 9}-C_{18:2}(2.2%)$ and ${\Delta}^{5, 11, 14}-C_{20:3}$ were also present. Levels of saturated fatty acid such as $C_{16:0}\;and\;C_{18:0}$ were as low as 7.5%. The seed oil of P. thunbergii predominantly comprised $C_{18:2}{\omega}_6(45.2%)$, and was then occupied by equal amounts ${\Delta}^{5, 9, 12}-C_{18:3}(18.1%)$ and $C_{18:1}{\omega}_9(18.1%)$. Its ${\Delta}^5, 11, 14}-C_{20:3}(5.8%)$ level was the highest in the samples tested. ${\Delta}^{5, 9}-C_{18:2}(2.8%)$ was also detected with other minor components. In the oils from the seeds of P. rigida, $C_{18:2}{\omega}_6$ was present as a main component, accompanied by $C_{18:1}{\omega}_9(21.6%)$ and ${\Delta}^{5, 9, 12}-C_{18:3}(20.3%)$. The latter showed higher level than in any other samples. A minor component corresponding to ${\Delta}^{5, 9, 12, 15}-C_{18:4}$(not confirmed by GC-Mass) occurred in P. thunbergii and P. rigida.

• BMB Reports
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• 제45권12호
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• pp.736-741
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• 2012

Certain members of the cytochromes P450 superfamily metabolize polyunsaturated long-chain fatty acids to several classes of oxygenated metabolites. An approach based on in silico analysis predicted that Streptomyces peucetius CYP107N3 might be a fatty acid-metabolizing enzyme, showing high homology with epoxidase enzymes. Homology modeling and docking studies of CYP107N3 showed that oleic acid can fit directly into the active site pocket of the double bond of oleic acid within optimum distance of $4.6{\AA}$ from the Fe. In order to confirm the epoxidation activity proposed by in silico analysis, a gene coding CYP107N3 was expressed in Escherichia coli. The purified CYP107N3 was shown to catalyze $C_9-C_{10}$ epoxidation of oleic acid in vitro to 9,10-epoxy stearic acid confirmed by ESI-MS, HPLC-MS and GC-MS spectral analysis.

• Bulletin of the Korean Chemical Society
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• 제28권6호
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• pp.941-946
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• 2007

Bacillus halodurans O-methyltransferase (BhOMT) is a S-adenosylmethionine (SAM or AdoMet) dependent methyltransferase. Three dimensional structure of the BhOMT bound to S-adenosyl-L-homocysteine (SAH or AdoHcy) has been determined by comparative homology modeling. BhOMT has 40% sequence identity with caffeoyl-CoA 3-O-methyltransferase (CCoAOMT) from alfalfa. Based on x-ray structure of CCoAOMT, three dimensional structure of BhOMT was determined using MODELLER. The substrate binding sites of these two proteins showed slight differences, but these differences were important to characterize the substrate of BhOMT. Automated docking study showed that four flavonoids, quercetin, fisetin, myricetin, and luteolin which have two hydroxyl groups simultaneously at 3'- and 4'-position in the B-ring and structural rigidity of Cring resulting from the double bond characters between C2 and C3, were well docked as ligands of BhOMT. These flavonoids form stable hydrogen bondings with K211, R170, and hydroxyl group at 3'-position in the Bring has stable electrostatic interaction with Ca2+ ion in BhOMT. This study will be helpful to understand the biochemical function of BhOMT as an O-methyltransferase for flavonoids.