• Bulletin of the Korean Mathematical Society
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• v.43 no.3
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• pp.543-549
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• 2006

Sung et al. [13] obtained a WLLN (weak law of large numbers) for the array $\{X_{{ni},\;u_n{\leq}i{\leq}v_n,\;n{\leq}1\}$ of random variables under a Cesaro type condition, where $\{u_n{\geq}-{\infty},\;n{\geq}1\}$ and $\{v_n{\leq}+{\infty},\;n{\geq}1\}$ large two sequences of integers. In this paper, we extend the result of Sung et al. [13] to a martingale type p Banach space.

• Journal of Powder Materials
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• v.8 no.3
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• pp.210-213
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• 2001

$Si_3N_4$/TiN nano/nano-type composites were successfully fabricated by the combination of a mechano-chemical grinding (MCG) method and a short time sintering process, and their wear resistance was evaluated. Powder mixtures of $\alpha-Si_3N_4$and Ti were prepared using mechano-chemical grinding process and the resulting nanocomposite powder mixtures were consolidated using pulsed electric current sintering (PECS). TEM observation showed that the nano/nano-type composites consisted of homogeneous and very fine matrix grains with the size less than 100 nm. The obtained $Si_3N_4$-based nano/nano-type showed high wear resistance and electric discharge machinability.

• Journal of Power System Engineering
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• v.4 no.4
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• pp.99-107
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• 2000

In this study several P type and N type ceramic semiconductors were prepared by atomic valence control and their electric resistivities were investigated with various concentrations of additive impurities. N-P junctions were made by thin film printing method and their varistor-like characteristics were investigated and their availability was discussed. The results are followings, 1) Some N type semiconductors with a proper concentration of additive impurity have minimum resistivities. 2) The N-P junction samples with ZnO as a constituent material of N type semiconductor have linearity in voltage-current characteristics, but the other N-P junction samples have the non-linearity, 3) Some N-P junction samples showed the good varistor-like characteristics.

• Communications of the Korean Mathematical Society
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• v.19 no.2
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• pp.293-305
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• 2004

Trotter-Kato type approximations of the convoluted solution operator families for the Volterra integral equations (V $E_n$): v(t)=$A_{n} \int_0^t v(t-s) d\mu_n(s) + f_n(t), t \geq 0$ and the convergence of the solutions to the equations (V $E_n$) are studied.

• Honam Mathematical Journal
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• v.24 no.1
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• pp.75-86
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• 2002

A Nielsen number $\bar{N}(f:X-A)$ is a homotopy invariant lower bound for the number of fixed points on X-A where X is a compact connected polyhedron and A is a connected subpolyhedron of X. This number is extended to Nielsen type numbers $\bar{NP_{n}}(f:X-A)$ of least period n and $\bar{N{\phi}_{n}}(f:X-A)$ of the nth iterate on X-A where the subpolyhedron A of a compact connected polyhedron X is no longer path connected.

• Communications of the Korean Mathematical Society
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• v.18 no.4
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• pp.603-613
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• 2003

When X is a threefold of general type, it is well known h/sup 0/(X, O/sub X/(nK/sub X/)) ≥ 1 for a sufficiently large n. When X(O/sub X/) 〉 0, it is not easy to obtain such an integer n. A. R. Fletcher showed that h/sup 0/(X, O/sub X/(nK/sub X/)) ≥ 1 for n = 12 when X(O/sub X/)=1. We introduce a technique different from A. R. Fletcher's. Using this technique, we also prove the same result as he showed and have a new result.

• Journal of Powder Materials
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• v.8 no.2
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• pp.110-116
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• 2001

Abstract To investigate the effect of mechanical alloying process to thermoelectric properties of PbTe sintered body, Pb-Te mixed powder with Pb : Te : 1 : 1 composition was mechanically alloyed using tumbler-ball mill. Thermoelectric properties of the sintered body were evaluated by measuring of the Seebeck coefficient and specific electric resistivity from the room temperature to 50$0^{\circ}C$. Sintered body of only mechanically alloyed PbTe powder showed p-type behavior at the room temperature, and occurred type transition from p-type to n-type at about 30$0^{\circ}C$. PbTe sintered body which was fabricated using heat treated powder in $H_2$ atmosphere after mechanical alloying showed stable n-type behavior under 50$0^{\circ}C$. N-type PbTe sintered body fabricated by mechanical alloying process had 4 times higher power factor than that fabricated by the melt-crushing process. Application of a mechanical alloying process to fabricate of n-type PbTe thermoelectric material seemed to be useful to increase the power factor of PbTe sintered body.

• Journal of Welding and Joining
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• v.28 no.2
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• pp.91-95
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• 2010

Stress distribution and deformation on the CT-type(Cross Tension type) spot welded lap joint subjected to out of plane tensile load were investigated by finite element method. Using the maximum principal stresses at the nugget edge obtained by FEM analysis, evaluated the fatigue strength of the CT-type spot welded lap joints having various dimensions and materials. and also, the influence of the geometrical parameters of CT-type spot welded lap joints on stress distribution and fatigue strength must be evaluated. thus, in this paper, ${\Delta}P-N_f$ curve were obtained by fatigue tests. Using these results, ${\Delta}P-N_f$ curve were systematically rearranged in the $\Delta\sigma-N_f$ relation with the hot spot stresses at the CT-type spot welded lab joints. It was found that the proposed $\Delta\sigma-N_f$ relation could provide a more reasonable fatigue design criterion for the CT-type spot welded lap joints.

• Korea Journal of Hospital Management
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• v.15 no.4
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• pp.100-124
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• 2010

This work was researched by practical method in a subjectivity study accessible in-depth, in sloughing off old habit of functional quantity analysis about Reception Type on policy reception of public & health campaign. The perception pattern come out in this study were divided into four types in Q-methodology. The result is as follows ; it is that divided'1[(N=16): Policy Improvement Type], 2[(N=7) : Public-relation Utility Type], 3[(N=19): Financial-continuance Type], 4[(N=11) : Healthy-prevention Orientation Type]'. Like this, it found that is very different type all over. Hereafter, this study is to ascertain acceptance behavior about Reception Type on policy reception of public & health campaign ; to offer a developmental suggestion about it.

• Communications of the Korean Mathematical Society
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• v.34 no.2
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• pp.573-583
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• 2019

This article studies the monotonicity, log-convexity of the modified Lommel functions by using its power series and infinite product representation. Some properties for the ratio of the modified Lommel functions with the Lommel function, sinh and cosh are also discussed. As a consequence, $Tur{\acute{a}}n$ type and reverse $Tur{\acute{a}}n$ type inequalities are given. A Rayleigh type function for the Lommel functions are derived and as an application, we obtain the Redheffer-type inequality.