• Bulletin of the Korean Chemical Society
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• v.28 no.4
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• pp.533-537
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• 2007

This paper describes the heteroepitaxial growth of single-crystalline 3C-SiC (cubic silicon carbide) thin films on Si (100) wafers by atmospheric pressure chemical vapor deposition (APCVD) at 1350 oC for micro/nanoelectromechanical system (M/NEMS) applications, in which hexamethyldisilane (HMDS, Si2(CH3)6) was used as a safe organosilane single-source precursor. The HMDS flow rate was 0.5 sccm and the H2 carrier gas flow rate was 2.5 slm. The HMDS flow rate was important in obtaing a mirror-like crystalline surface. The growth rate of the 3C-SiC film in this work was 4.3 μm/h. A 3C-SiC epitaxial film grown on the Si (100) substrate was characterized by X-ray diffraction (XRD), transmission electron microscopy (TEM), reflection high energy electron diffraction (RHEED), atomic force microscopy (AFM), X-ray photoelectron spectroscopy (XPS) and Raman scattering, respectively. These results show that the main chemical components of the grown film were single-crystalline 3C-SiC layers. The 3C-SiC film had a very good crystal quality without twins, defects or dislocations, and a very low residual stress.

• Journal of Korean Society for Quality Management
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• v.26 no.1
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• pp.48-60
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• 1998

This paper proposes a fourth generation index $C_{psk}$, constructed from $C_{psk}$, by introducing the factor｜$\mu$-T｜ in the numerator as an extra penalty for the departure of the process mean from the preassigned target value T. The motivation behind the introduction of $C_{psk}$ is that when $T\neqM$ process shifts away from target are evaluated without respect to direction. All indices that are now in use assume normally distributed data, and any use of the indices on non-normal data results in inaccurate capability measurements. In this paper, a new process capability index $C_{psk}$ is introduced for non-normal process. The Pearson curve and the Johnson curve are selected for capability index calculation and data modeling the normal-based index $C_{psk}$ is used as the model for non-normal process. A significant result of this research find that the ranking of the six indices, $C_{p}$, $C_{pk}$, $C_{pm}$, ${C^*}_{psk}$, $C_{pmk}$, $C_{psk}$in terms of sensitivity to departure of the process median from the target value from the most sensitive one up to the least sensitive are $C_{psk}$, $C_{pmk}$, ${C^*}_{psk}$,$C_{pm}$, $C_{pk}$, $C_{p}$.

• Journal of the Korean Ceramic Society
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• v.52 no.6
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• pp.429-434
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• 2015

This study investigates the macroscopic wear behaviors of C/C and C/C-SiC composites coated with hafnium carbide (HfC). To improve the wear resistance of C/C composites, low-pressure chemical vapor deposition (LPCVD) was used to obtain HfC coating. The CVD coatings were deposited at various deposition temperatures of 1300, 1400, and $1500^{\circ}C$. The effect of the substrate material (the C/C substrate, the C/C-CVR substrate, or the C/C-SiC substrate deposited by LSI) was also studied to improve the wear resistance. The experiment used the ball-on-disk method, with a tungsten carbide (WC) ball utilized as an indenter to evaluate the wear behavior. The HfC coatings were found to effectively improve the wear resistance of C/C and C/C-SiC composites, compared with the case of a non-coated C/C composite. The former showed lower friction coefficients and almost no wear loss during the wear test because of the presence of hard coatings. The wear scar width was relatively narrower for the C/C and C/C-SiC composites with hafnium coatings. Wear behavior was found to critically depend on the deposition temperature and the material. Thus, the HfC-coated C/C-SiC composites fabricated at deposition temperatures of $1500^{\circ}C$ showed the best wear resistance, a lower friction coefficient, and almost no loss during the wear test.

• Proceedings of the KSR Conference
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• 2005.05a
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• pp.712-717
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• 2005

When the weight if a concrete member makes problems, or when the cost of the concrete is relatively high, it may be economical to use a hollow concrete member. But a hollow R.C column may have poor ductility because of the brittle failure at the inner face of the hollow R.C column. This brittle failure results from the absence of the confinement at the inner face of the hollow R.C column. To avoid this brittle failure an internally confined hollow R.C column by a steel tube was developed before. In this study, a hollow R.C column is internally confined by a corrugated steel tube instead of a general flat steel tube. And a column ductility is performed. Test results show that the energy ductility ratio of a internally confined hollow R.C column by a by a corrugated steel tube corresponds to $80\%$ of the energy ductility ratio of a general solid R.C column.

• The Plant Pathology Journal
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• v.21 no.3
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• pp.275-282
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• 2005

A chitinolytic bacterium, Chromobacterium sp. strain C-61, was found strongly antagonistic to Rhizoctonia solani, a causal agent of damping-off of eggplant. In this study, the biocontrol activity and enzymatic characteristics of strain C-61 were compared with its four Tn5 insertion mutants (C61-A, -B, -C, and -D) that had lower chitinolytic ability. The chitinase activity of a 2-day old culture was about $76\%,\;49\%\;and\;6\%$ level in C61-A, C61-B and in C61-C, respectively, compared with that of strain C-61. The $\beta-N-acetylhexosaminidase$(Nahase) activity was little detected in strain C-61 but increased largely in C-61A, C61-B and C61-C. Activities of chitinase and Nahase appeared to be negatively correlated in these strains. Another mutant, C-61D, produced no detectable extracellular chitinase and Nahase. The in vitro and in vivo biocontrol activities of strain C-61 and its mutants were closely related to their ability to produce chitinase but not Nahase. No significant differences in population densities between strain C-61 and its mutants were observed in soil around eggplant roots. The results of SDS-PAGE and isoelectrofocusing showed that a major chitinase of strain C-61 is 54-kDa with pI of approximately 8.5. This study provides evidence that the biocontrol activity of Chromobacterium sp. strain C-61 against Rhizoctonia solani depends on the ability to produce chitinase with molecular weight of 54-kDa and pI of 8.5.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09b
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• pp.859-860
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• 2006

TiC-$TiB_2$-SiC system was a ternary eutectic, whose eutectic composition was 34TiC-$22TiB_2$-44SiC (mol%). TiC-$TiB_2$-SiC ternary eutectic composite were synthesized by a floating zone method using TiC, $TiB_2$ and SiC powders as starting materials. The TiC-$TiB_2$-SiC eutectic composite showed a lamellar texture. TiC(022), $TiB_2(010)$ and SiC(111) of the eutectic composite were perpendicular to the growth direction. TiC-$TiB_2$-SiC ternary eutectic composite had specific relationship among the crystal planes: TiC[011]//$TiB_2[010]$//SiC[112], TiC(200)//$TiB_2$(001)//SiC(402) and $TiC(1\bar{1}1)$//$TiB_2(101)$//SiC(220).

• Journal of Life Science
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• v.17 no.7 s.87
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• pp.976-982
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• 2007

The purpose of this study was to determine the modulating effects of histone deacetylase inhibitor, trichostatin A, on the differentiation of mouse C2C12 myoblasts. We demonstrated that trichostatin A induced morphological changes of C2C12 myoblasts into smooth muscles and significantly increased the gene expression of smooth muscle markers including smooth muscle ${\alpha}-actin$ and transgelin. These results were due to the change in the expression level of cell cycle regulators in trichostatin A-treated C2C12 cells. Real-time PCR data revealed that cyclin dependent kinase inhibitor, p21, mRNA expression was significantly increased in trichostatin A-treated C2C12 cells. However, trichostaDn A rapidly decreased cyclin Dl mRNA expression necessary for cell cycle progression in 24hr after treatment. In conclusion, the strong inhibitory effects of trichostatin A on histone deacetylation induced transdifferentiation of C2C12 myoblasts into smooth muscle cells and these results are partly due to the changes in the expression of cell cycle regulators such as p21 and cyclin D1.

• Bulletin of the Korean Mathematical Society
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• v.47 no.2
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• pp.319-339
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• 2010

In this paper, we prove that if $f^nf'\;-\;P$ and $g^ng'\;-\;P$ share 0 CM, where f and g are two distinct transcendental meromorphic functions, $n\;{\geq}\;11$ is a positive integer, and P is a nonzero polynomial such that its degree ${\gamma}p\;{\leq}\;11$, then either $f\;=\;c_1e^{cQ}$ and $g\;=\;c_2e^{-cQ}$, where $c_1$, $c_2$ and c are three nonzero complex numbers satisfying $(c_1c_2)^{n+1}c^2\;=\;-1$, Q is a polynomial such that $Q\;=\;\int_o^z\;P(\eta)d{\eta}$, or f = tg for a complex number t such that $t^{n+1}\;=\;1$. The results in this paper improve those given by M. L. Fang and H. L. Qiu, C. C. Yang and X. H. Hua, and other authors.

• Journal of the Korean Institute of Telematics and Electronics
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• v.3 no.2
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• pp.10-17
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• 1966

A method by which solutions of the differential equations of any other distributed circuits can be obtained is described when the solution of the differential equation of an R-C distributed amplifier is known. A graphical method of transforming any R-C ditributed circuit into an equivalent circuit which has a constant R(x)$cdot$C(x) was also obtained. The theoretical verification of this method is possible. For simplicity, any R-C distributed circuit can be transformed into an equivalent circuit which is a distributed circuit of either constant R(x) or C(x). Using this equivalent circuit and considering a lumped circuit, an approximate analysis and synthesis can be made simply.

• BMB Reports
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• v.30 no.6
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• pp.397-402
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• 1997

A thiol-specific spin label was attached to cysteine-102 of yeast cytochrome c and electron paramagnetic resonance (EPR) spectra were measured as a function of added cytochrome c oxidase concentration. The intensity decreased due to line broadening as cytochrome c formed a complex with cytochrome c oxidase and reached a minimum when the ratio of cytochrome c to cytochrome c oxidase became one. Replacement of either Lys-72 or Lys-87 of cytochrome c by Glu did not result in a significant change in binding affinity. Interestingly the K72E mutant, unlike K87E, had a much lower rate of electron transfer than the wild type. These results indicate that many positively charged residues as a group participate in complex formation but Lys-72 might be important for cytochrome c to be locked in an orientation for an efficient electron transfer. A stoichiometry of 1 was also confirmed by optical absorption of the cytochrome c-cytochrome c oxidase complex which had been run through a gel chromatography cloumn to remove unbound cytochrome c. The EPR spectrum of this 1:1 complex, however, was a mixture of two components. This explains a biphasic kinetics for a single binding site on cytochrome c oxidase without invoking conformational transition.