• Journal of the Korean Crystal Growth and Crystal Technology
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• v.10 no.5
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• pp.356-361
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• 2000

The radial position of OiSF-ring has been meaningful data in industry. Thus it's position was calculated by application of (V/G)/sub crit/ = 0.138 ㎟/minK and point defect dynamics for industrial scale grower with various pull rates. After the calculation, compared with experimental result. OiSF-ring diameters expected with calculation were good agreement with experimental results. In order to show validity of the predicted temperature distribution using STHAMAS which is one of the global simulator for Cz crystal growing, temperature was measured along the axis of crystal using thermocouples, and compared with the calculated temperature. We found the effective thermal conductivity K/sub m/ (r) which gives in accordance with the temperature distribution at the axis of crystal and crystal/melt interface shape between experimental and computational results. Therefore, effective thermal conductivity K/sub m/ (r) was applied instead of solving melt convection problem.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.18 no.11
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• pp.1170-1176
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• 2008

In this study, we propose a new method to control both the beat clarity and beat period in a ring structure. An equivalent ring which satisfies the measured mode condition is determined by using the equivalent ring theory. Theoretical analysis and finite element analysis on the equivalent ring are performed to investigate the effect of the local structural modification on the beat clarity and beat period. Beat clarity and period are improved by attaching asymmetric mass or decreasing local thickness. Through the analysis on the equivalent ring, the proper position and the amount of the local variation are determined to satisfy the required clarity and period condition. All the analysis results are compared and verified by the experiment.

• Archives of Pharmacal Research
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• v.16 no.1
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• pp.62-67
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• 1993

A series of 12 pyrimidine derivatives were prepared and tested in vitro against growth, sporulation and nucleic acids of Fusarium oxysporum f. sp. lycopersici and Helminthosporium oryzae. Intorduction of thiazole ring together with two aryl groups to 2-aminopyrimidine induced drastic toxicity for both fungi. Pyrimidine derivatives with aryl groups were less toxic. Nitro groups were found to enhance the toxicity of the pyrimidine derivatives especially when substituted in ortho-position of the aryl groups. Inhibition of nudeic acids synthesis of both fungi was attributed mainly to the presence of thiazole ring.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.11
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• pp.1802-1812
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• 2001

The theoretical method is developed to investigate the effects of ring stiffeners on free vibration characteristics and transient response for the ring stiffened composite cylindrical shells subjected to the impulse pressure Loading. In the theoretical procedure, the Love's thin shell theory combined with the discrete stiffener theory to consider the ring stiffening effect is adopted to formulate the theoretical model. The concentric or eccentric ring stiffeners are laminated with composite and have the uniform rectangular cross section. The modal analysis technique is used to develop the analytical solutions of the transient problem. The analysis is based on an expansion of the loads, displacements in the double Fourier series that satisfy the boundary conditions. The effect of stiffener's eccentricity, number, size, and position on transient response of the shells is examined. The results are verified by comparison with FEM results.

• Bulletin of the Korean Chemical Society
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• v.24 no.9
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• pp.1289-1292
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• 2003

An efficient synthetic route for preparing novel $4'{\alpha}$-C phenyl branched carbocyclic nucleoside is described. The installation of phenyl group at the $4'$-position of carbocyclic nucleoside was successfully accomplished via a sequential [3,3]-sigmatropic rearrangement and ring-closing metathesis (RCM) beginning from simple ketone such as 2-hydroxy acetophenone.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.228-229
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• 2008

In this study, we propose an effective method to improve the clarity and period of the beat in a ring structure. Ring is an simplified model of a Korean bell, in which beating vibration and sound are very important features. An equivalent ring theory is applied and finite element analysis on the equivalent ring is performed to determine the condition of the asymmetric element for the clear and proper period beat. The clarity and the period of the beat are improved by attacking asymmetric mass and decreasing local thickness. Using the equivalent ring, the amount and position of the local variation for the required beat condition are determined and the results are verified by experiment.

• Proceedings of the KSME Conference
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• 2001.06a
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• pp.883-888
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• 2001

The theoretical method is developed to investigate the effects of ring stiffeners on free vibration characteristics and transient response for the ring stiffened composite cylindrical shells subjected to the impulse pressure loading. In the theoretical procedure, the Love's thin shell theory combined with the discrete stiffener theory to consider the ring stiffening effect is adopted to formulate the theoretical model. The concentric or eccentric ring stiffeners are laminated with composite and have the uniform rectangular cross section. The modal analysis technique is used to develop the analytical solutions of the transient problem. The analysis is based on an expansion of the loads, displacements in the double Fourier series that satisfy the boundary conditions. The effect of stiffener's eccentricity, number, size, and position on transient response of the shells is examined. The theoretical results are verified by comparison with FEM results.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.471-477
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• 2003

The floating ring seal is often used in the turbopump (TP) unit of liquid rocket engine (LRE) owing to its inherent ability of minimizing the leakage flow and superior dynamic characteristics as well. This paper describes the test results concerned with the lock-up and dynamic characteristics of the floating ring seals in the turbopump. The characteristics of the floating ring seals were extracted from the frequency response function (FRF) by instrumental variable method. The experiment was tested at 7.0MPa and 0-24,800 rpm. And the test results were introduced about the dynamic characteristics of floating ring seal related with the eccentricity and attitude angle.

• Bulletin of the Korean Chemical Society
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• v.20 no.6
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• pp.663-666
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• 1999

The 4-methylene-1,3-dioxolane(4-MDO) derivatives with dimethoxyphenyl group on the 2-position of 1,3-dioxolane ring, 2-(x,y-dimethoxyphenyl)-4-MDO derivatives (x,y=2,3(1b), 2,4(2b), 2,5(3b) and 3,4(4b)) were prepared by acelalizationof the corresponding benzaldehyde with 3-chloro-1,2-propanediol, followed by dehydrochlorination. 2-(Dimethoxy)phenyl-4-MDO derivatives underwent polymerization wiht ring opening as will as cyclization reaction to afford a mixture of the ring-opened polymer and 3(2H)-dihydrofuranone derivative with boron trifluoride as a cationic catalyst. Both the methylene group and 1,3-dioxolane ring were participated in the reaction with cationic catalyst. The key intermediate of the polymerization is a benzyl cation generated by ring opening, and the cyclization reaction proceed via proton addition to oxygen atom of 1,3-dioxolane ring.

• Archives of Pharmacal Research
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• v.15 no.3
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• pp.256-262
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• 1992

For the evaluation of the role of substituents of ar-turmerone for its anticancer activity, ar-turmerone (1a) and its analogs like 2-methyl-6-(4'-methyphenyl)-2-octen-4-one (1b), 2-methyl-6-phenyl-2-hepten-4-one (1c), 2-methyl-6-phenyl-2-octen-4-one (1d) and 2 methyl-6-(trans-4'-methylcyclohexyl)-2-hepten-4-one (1e) were preparedd and their cytotoxic activities against $L_{1210}$ cell were determined. Omission of methyl group at para-position dose not variate the cytotoxicity of ar-turmerone. Elongation of alkyl group at 6-position decreases $ED_{50}$ value. Saturation of aromatic ring of ar-turmerone markedly decreases the cytotoxicity. Therefore the smaller size of alkyl group at 6-position and aromatic ring of ar-turmerone should be essential for exhibiting its anticancer activity.