• Bulletin of the Korean Chemical Society
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• 제33권3호
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• pp.1042-1046
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• 2012

The kinetics and mechanism of the pyridinolysis ($XC_5H_4N$) of diethyl isothiocyanophosphate are investigated in acetonitrile at $55.0^{\circ}C$. The Hammett and Bronsted plots for substituent X variations in the nucleophiles exhibit the two discrete slopes with a break region between X = 3-Ac and 4-Ac. These are interpreted to indicate a mechanistic change at the break region from a concerted to a stepwise mechanism with rate-limiting expulsion of the isothiocyanate leaving group from a trigonal bipyramidal pentacoordinated intermediate. The relatively large ${\beta}_x$ values with more basic and less basic pyridines imply much greater fraction of frontside nucleophilic attack TSf than that of backside attack TSb.

• 한국수산과학회지
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• 제36권4호
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• pp.346-351
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• 2003

Single-cell gel electrophoresis (comet assay) was used to detect DNA single strand break in blood cells from several marine fish species. Three fish species were collected from Georgia coastal area. Mummichog, Fundulus heteroclitus showed higher DNA damage than sea bass, Lateolabrax japonicus and trout, Oncorhynchus masou masou under the same experimental conditions. Mummichogs had more alkaline-labile sites on their DNA than other fish species. The comet assay with mummichog blood cells at pH 12.5 showed a dose-response curve with the increasing concentrations of hydrogen peroxide. While the isolated leucocytes showed no increase of DNA damage after in vitro exposure to 2-methyl-1,4-naphthoquinone (MNQ), erythrocytes showed dose-dependent DNA damage. These results indicate that the comet assay can be applied successfully as a bioassay using erythrocyte for environmental monitoring.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.664-669
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• 2005

In this note, we present a different asymptotes from the standard approximate lines of the Bode magnitude plot. Wherein the pseudo break frequency is defined in terms of coefficients of denominator and numerator polynomials of the transfer function instead of its poles and zeros. Several comparative examples are given. This result can be used for the characteristic ratio assignment(CRA) [1], [2] with frequency response requirements, which is a method of designing linear controller in parameter space.

• 대한기계학회논문집
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• 제19권3호
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• pp.731-740
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• 1995

The objective of this paper is to develop defect assessment technology for integrity evaluation of CANDU pressure tubes. In fracture mechanics analysis, three-dimensional and two-dimensional (line-spring model) finite element analyses were performed to obtain the stress intensity factor for axial and circumferential surface cracks. In leak before break (LBB) analysis, heat transfer analyses for through-wall cracks were performed by considering the cooling effect and the LBB application time was computed. It was shown that the analytical results obtained in this study provide less-conservative but accurate solution for defect assessment of CANDU pressure tubes.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1996년도 추계학술대회 논문집
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• pp.538-541
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• 1996

The flow of the molten drop in the GMAW was observed to explain the mechanism of its formation and break-up process. Fluid flew analysis was made with the assumption that the electrode wire acts like fluid, and it is shown how the convection of the drop inside affects its flow, from the formation to the break-up of the drop. In later part, the process of the spray mode development at high current is shown, as well as the one of the globular mode, by the fluid flow analysis.

• Bulletin of the Korean Chemical Society
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• 제35권4호
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• pp.1016-1022
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• 2014

The kinetic studies on the reactions of O-methyl N,N-diisopropylamino phosphonochloridothioate with X-anilines and X-pyridines have been carried out in acetonitrile. The free energy relationship with X in the anilines exhibits biphasic concave upwards with a break region between X = (H and 4-F), giving unusual negative ${\beta}_X$ and positive ${\rho}_X$ values with weakly basic anilines. The unusual phenomenon is rationalized by isokinetic relationship. A stepwise mechanism with a rate-limiting leaving group departure from the intermediate is proposed based on the selectivity parameter and variation trend of the deuterium kinetic isotope effects with X. The free energy relationship with X in the pyridines exhibits biphasic concave upwards with a break point at X = 3-MeO. A concerted mechanism is proposed based on relatively small ${\beta}_X$ value, and frontside and backside nucleophilic attack are proposed with strongly and weakly basic pyridines, respectively.

• Bulletin of the Korean Chemical Society
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• 제33권7호
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• pp.2260-2264
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• 2012

The kinetics and mechanism of the pyridinolysis ($XC_5H_4N$) of dimethyl isothiocyanophosphate are investigated in acetonitrile at $55.0^{\circ}C$. The Hammett and Br$\ddot{o}$nsted plots for substituent X variations in the nucleophiles exhibit two discrete slopes with a break region between X = 3-Ac and 4-Ac. These are interpreted to indicate a mechanistic change at the break region from a concerted to a stepwise mechanism with a rate-limiting expulsion of the isothiocyanate leaving group from the intermediate. The relatively large ${\beta}x$ values imply much greater fraction of frontside nucleophilic attack TSf than that of backside attack TSb. The steric effects of the two ligands play an important role to determine the pyridinolysis rates of isothiocyanophosphates.

• Elastomers and Composites
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• 제57권4호
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• pp.165-174
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• 2022

The effect of fumed silica loading on the thermal stability and mechanical properties of fluorosilicone (FVMQ) rubber was investigated. The distribution of fumed silica inside FVMQ was characterized using scanning electron microscopy, and the thermal stability of composites was evaluated using thermogravimetric analysis and by the changes in mechanical performance during thermo-oxidative aging. The function mechanism of fumed silica was studied by Fourier transform infrared spectroscopy. The results show that with increasing silica content, the crosslink density of composites, the modulus at 100%, and tensile strength also increased, whereas the elongation at break decreased. Furthermore, increasing the silica content of composites increased the initial decomposition temperature (T_d) and residual weight of the composite after exposure to nitrogen. In addition, the thermal oxidative aging experiment demonstrated improved aging resistance of the FVMQ composites, including lower change in tensile strength, elongation at break, and modulus at 100%.

• 한국산림과학회지
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• 제40권1호
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• pp.57-62
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• 1978

This study was carried out to determine the proper transplanting time of Platanus occidentalis L. (plane tree, sycamore) with 5 to 6 cm and 25 to 30 cm in diameter of breast height at the forest nursery of Chonnam National University in 1977. For that purpose, the experiment of the time of transplantation, and the moisture content and soluble sugar were analysed. The results are as follows: 1. Both its rooting and growth were slightly different in the period of January to early April (before bud-break), but remarkably declined after its bud-break (mid-April to May). 2. And also, its moisture content and soluble sugar were slightly different (January to early April), but, on the other hand, considerably increased in the content of moisture and sharply decreased in soluble sugar after bud-break (mid-April to May). 3. In comparision with healthy trees, rooting and growth of trees infected with Cankers were unusually retarded and its moisture content and soluble sugar were much less. 4. The proper time to plant sycamore was recognized to be the period of November to March, since the higher amounts of soluble sugar and the lesser amounts of moisture in that period. 5. The sudden exposure to the sun of the boles of diseased and wounded trees could be in death in case of sun-scald on the side of south-west. 6. Pruning wounds should be treated with an antiseptic, as soon as they are made, to prevent entrance of decay or disease while the wound is healing. 7. The wound and sun-scald can be presented by covering the trunk with straw ropes before transplantations.

• 복식
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• 제44권
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• pp.37-56
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• 1999

In clothing, a tendency of Bisexuality is in case of wearing clothing of the opposite sex, the mixing of modeling principle and characteristic of man and woman, the exclusion characteristic of sexuality that present sexlessness-the third sex. They-Designer Gabrielle Chanel, YSL, Giorgio Armani-give characteristic of man's fashion to women's fashion. However, the consciousness in design is different. Chanel apply principle of man's suit to woman's wear to express authority and power about gender image, hereby she express women liberation and equality of man and woman based on social ideology through fashion especially, she express women's sexual independency and self assurance to her clothing. YSL express liberal and bold women that pursuit reasonal and liberal life in 1970. As he apply tailoed suit's rigidity to women's wear, he made 'pants look' universal in women's wear through“Dress for success”in modern life. Armani apply successful modern image to women's wear, so he express women's image of confident intellegent as well as feminine image. He focus women's new image as man living liberal and indivisual life excluding social category rather than will of equality of man and women. Gernreich break sexual prejudice and release women freely, furthermore, as he express concern of sexuality pursuit liberty of mankind surpassing sex distinction with women liberty. Gianni Versace pursuit mix and extinguishment of sexual image many-sided, and break fixed idea of sex, and reprovide feminine and masculine image. So his design tend homosexuality because he regard women's glamor and ostensible sexuality as standard of beauty, he apply this to man's wear as well as women's wear. With this, he expresses sensitive and liberal man's that break characteristic of Gender that symbolize power and authority in man's wear through 'Without ties'.