• Journal of the Korean Crystal Growth and Crystal Technology
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• v.22 no.1
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• pp.51-56
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• 2012

In the present study, we investigated the effect of mechanical alloying (MA) on the formation of amorphous VCo system through solid state reaction during ball milling. Two types of powder samples, ${\sigma}$-VCo intermetallic compound and $V_{50}Co_{50}$ powder mixture, were applied as a starting materials. With increasing milling time, a structural characteristics into the amorphous state is distinctly observed from the structural factor and radial distribution by X-ray diffraction. Amorphization has been observed in all two types of samples after the milling for 120 hrs. DSC spectrum of $V_{50}Co_{50}$ powder sample milled for 60 hrs indicates a sharp exothermic peak from the crystallization at $600^{\circ}C$. The structure factor, S(Q) and radial distribution function, RDF(r), observed by X-ray diffraction gradually change into a structure characteristic of an amorphous state with increasing MA time.

• Applied Biological Chemistry
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• v.40 no.1
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• pp.80-84
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• 1997

Series of new chiral N-substituted benzotriazol-1-yl derivatives were synthesized and their fungicidal activities in vitro against gray mold(Botrytis cinerea), black spot(Alternaria kikuchiana) and phytophthora blight(Phytophthora capsici) were measured by the agar medium dilution method. The substituents effects between the fungicidal activities (obs. $pI_{50}$) and a various physicochemical parameters of phenoxy or thiophenoxy group(X) & alkyl or phenyl group(Y) were analyzed by the multiple regression technique. From the analyzed substituent effects, the structure-activity relationship(SAR) equations shows that the antifungal activities depend on the parameters for the optimal molecular hydrophobicity($({\Sigma}logP)_{opt}$), Van der Waals (${\Sigma}Vw$>0) volume(${\AA}^3$) and inductive constant with electron withdrawing group(${\sigma}_I$,Y>0). The activity in affected by the inductive effect (${\sigma}_I$,Y>${\sigma}_g$X) of Y-group rather than the X-group. The phenoxy substituents, 1, showed higher antifungal activity tn the thiophenoxy substituents, 2. For 1, polar substituent constant(${\sigma}^*$) was an important factor in determining the activity. And the tribromomethyl substituent, 1g showed the highest activity against the tee fungi.

• Journal of the Korean Statistical Society
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• v.28 no.4
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• pp.503-513
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• 1999

The Bayes factor for the identification of stationary ARM(p,q) models is exactly computed using the Monte Carlo method. As priors are used the uniform prior for (\ulcorner,\ulcorner) in its stationarity-invertibility region, the Jefferys prior and the reference prior that are noninformative improper for ($\mu$,$\sigma$\ulcorner).

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1664-1667
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• 2005

The main function of Ball-Stop part is to operate power shift for vehicle with more than 5 ton when a driver changes gear using suitable force. This paper presents the implementation of a DFSS(Design For Six Sigma) for robust design of Ball-Stop part of power shift. The factors influencing Ball-Stop part performance is derived to find control factor. Based on this factor, contact force between head and detent pin analysis is performed to get optimal factor is analyzed and compared with contact force test result to verify reliability of design. This makes clear the reason why the proposed one is necessary and the role of DFSS.

• Journal of Ocean Engineering and Technology
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• v.16 no.3
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• pp.54-58
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• 2002

This study investigates a relationship between fracture mechanics parameters (Stress Intensity Factor Range: ΔK, Maximum Stress Intensity Factor; Kmax) and X-ray parameters (residual stress:$\sigma$r half-value breadth: B) for SG365 steel at elevated temperature up to 30$0^{\circ}C$. The fatigue crack propagation test were carried out and X-ray diffraction technique according to the direction of crack length was applied to fatigue fractured surface. The residual stress on the fracture surface was found to increase at low ΔK region, to reach a maximum value at a certain value of Kmax or ΔK and then to decrease. Residual stress was independent of stress ratio by arrangement of ΔK and half value breadth were independent of the arrangement of Kmax. The equation of $\sigma$r-ΔK was established by the experimental data. therefore, fracture mechanics parameters could be estimated by the measurement of X-ray parameters.

• Journal of Digital Convergence
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• v.10 no.2
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• pp.225-229
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• 2012

A reformer for a small fuel cell system is an apparatus which converts hydrocarbon fuel into hydrogen-rich gas. Among many indices of a reformer, the most crucial index of a reformer is CO concentration in the off-gas out of reformer which must be controled under 5ppm for the efficiency and performance of a system. This paper suggests the criteria of a reformer operation for the stability of a reformer in a fuel cell system by deducing crucial indices and improving processes. The six-sigma technique was applied to verify the optimum control and operation of a reformer of a fuel cell combined heat and power system. The result of temperature control of each parts of a reformer system is the concentration of CO which is the most important factor for the operation of a fuel cell system. The temperature of the parts of a reformer, MTS, LTS and Prox, were controled so that the concentration of CO.

• Journal of the Korean Vacuum Society
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• v.15 no.6
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• pp.619-623
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• 2006

The most important factor which determines resonance characteristics of FBAR(Film Bulk Acoustic Resonator) is the piezoelectricity of piezoelectric film. The piezoelectric properties of ZnO thin films which is strong as FBAR piezoelectric film is determined by the degree of c-axis preferred orientation with (002) plan. Therefore, many researchers have been interested in the study on the preferred orientation of the piezoelectric thin film. This paper has studied the preferred orientation of ZnO piezoelectric thin films using the helped seed layer of ZnO. The result shows that the c-axis ZnO thin films with columnar grains that the value of standard $deviation(\sigma)$ of XRD rocking curve is of $\sigma=1.15^{\circ}$ have the excellent piezoelectric property.

• Journal of the Korean Ceramic Society
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• v.32 no.11
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• pp.1292-1300
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• 1995

The ionic conductivity of NASICON solid electrolytes was simulated by using Monte Carlo Method (MCM). There were included two conduction paths: (1) Na1-Na2 and (2) Na1-Na2 including Na2-Na2. We assumed that mid-Na ions provde an additional driving force for Na mobile ions due to the interionic repulsion between Na1 and Na2 ions. The inflection point of vacancy availability factor, V has been shown at nearby x=2, the maximum mid-Na ions. The inflection point of vacancy availability factor, V has been shown at nearby x=2, the maximum mid-Na sites are occupied. The effective jump frequency factor, V has been shown at nearby x=2, the maximum mid-Na sites are occupied. The effective jump frequency factor, W increased rapidly with the composition at low temperature, but decreased at high temperature region. On Na1-Na2 conduction path, the minimum of charge correlation factor, fc and the maximum of $\sigma$T were appeared at x=2.0. this indicated that mid-Na ions affect on the high ionic conductivity behavior. At the whole range of NASICON composition, 1n $\sigma$T vs. 1/T* plots have been shown Arrhenius behavior but 1n (VWFc) vs. 1/T* have been shown the Arrhenius type tendency at x=2, which mid-Na is being the maximum. The results of MCM agreed with the experimental one when the chosen saddle point value was 6$\varepsilon$ : 3$\varepsilon$. Here the calculated characteristic parameter of materials, K and the phase transition temperature were -4.001$\times$103 and 178$^{\circ}C$ (1/T*=1.92, 1000/T=2.22), respectively.

• Journal of the Korean Statistical Society
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• v.29 no.1
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• pp.95-108
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• 2000

Consider the oblique factor model X=Af＋$\varepsilon$, with defining relation $\Sigma$=Λ$\Phi$Λ'＋Ψ. This paper is concerned with suggesting an optimal Bayes criterion for determining the number of factors in the model, i.e. dimension of the vector f. The use of marginal likelihood as a method for calculating posterior probability of each model with given dimension is developed under a generalized conjugate prior. Then based on an appropriate loss function, a Bayes rule is developed by use of the posterior probabilities. It is shown that the approach is straightforward to specify distributionally and to imploement computationally, with output readily adopted for constructing required cirterion.

• Proceedings of the Microbiological Society of Korea Conference
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• 2004.05a
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• pp.85-86
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• 2004