• The Journal of the Acoustical Society of Korea
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• v.5 no.4
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• pp.16-21
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• 1986

위상이 불규칙적으로 변하는 RZ와 NRZ 신호에 대하여 전력 밀도 스펙트럼을 구하였고 신호의 펄스폭 점유율은 가변으로 하였다. 이때 불규칙 위상의 확률분포는 구간 내에서 일정하다고 가정한다. 단극성 지터없는 신호는 입력된 신호의 기본 주파수의 정수배마다 스펙트럼의 이산성분이 존재하며 이 것은 데이터를 찾기 위한 타이밍 신호로써 이용된다. 그러나 지터가 유입되는 경우에는 이 이산 신호성 분이 점차 감소하게 되며, 균일한 확률 분포를 갖는 지터의 경우는 완전히 소멸하였음을 확인하였다.

• Journal of the Korean Statistical Society
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• v.24 no.1
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• pp.233-242
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• 1995

In this paper we will prove the existence and uniqueness of the smoothest density with prescribed moments. The space of functions considered is the Sobolev space $W^2_m[0,1]$ and the target functional to be minimized is the seminorm $$\mid$$\mid$f^{(m)}$\mid$$\mid$_{L^2}$, which measures the roughness of the function f.

• Journal of Powder Materials
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• v.4 no.2
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• pp.83-89
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• 1997

A finite element analysis to solve the coupled thermomechanical problem in the plane strain upsetting of the porous metals was performed. The analysis was formulated using the yield function advanced by Lee and kim and developed using the thermo-elasto-plastic time integration procedure. The density and temperature dependent thermal and mechanical properties of porous metals were considered. The internal heat generation by the plastic deformation and the changing thermal boundary conditions corresponding to the geometry were incorporated in the program. The distributions of the stress, strain, pressure, density and temperature were predicted during the free resting period, deformation period and dwelling period of the forging process.

• Proceedings of the KWS Conference
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• 2000.10a
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• pp.201-203
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• 2000

In this study, effect of welding parameters on the defect density in the weldments produced by high frequency electric resistance welding process. The defect density measured by X-ray radiography showed a W-type curve as a function of heat input rate. The mechanisms of the such behavior were discussed based on the chemical compositions of the oxides formed at the weldments.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.04a
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• pp.292-299
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• 1998

Case hardening behavior of tool steel(SK5) was investigated after YAG laser irradiation. In the case of beam passes, martensite formed in the melt zone and in former pearlite regions of the austenization zone exhibited very high Vickers Hardness values. The molten depth and radius, micro structure, hardness were investigated as a function of defocusing distance, pulse width, and power density.

• Journal of the Korean Institute of Telematics and Electronics A
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• v.30A no.10
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• pp.20-26
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• 1993

The base-collector capacitance of an npn bipolar transistor in bipolar or BiCMOS technology has significant influence on the switching performances, and comprises pnjunction component and MOS component. Both components have complicated dependences on the isolation oxide structure, epitaxial doping density, and bias voltage. Analytical/empirical formulas for both components are derived in this paper for a generic isolation structure as a function of epitaxial doping density and bias voltage based on some theoretical understanding and two-dimensional device simulations. These formulas are useful in estimating the effect of device isoation schemes on the switching speed of bipolar transistors.

• Journal of the Korean Data and Information Science Society
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• v.7 no.2
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• pp.189-201
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• 1996

In this paper, we study the saddlepoint approximations for the ratio of independent random variables. In Section 2, we derive the saddlepoint approximation to the density. And in Section 3, we derive two approximation formulae for the tail probability, one by following Daniels'(1987) method and the other by following Lugannani and Rice's (1980). In Section 4, we represent some numerical examples which show that the errors are small even for small sample size.

• Journal of applied mathematics & informatics
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• v.33 no.1_2
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• pp.203-210
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• 2015

We consider fractional Brownian motion and FARIMA process with Gaussian innovations and show that the suitably scaled distributions of the FARIMA processes converge to fractional Brownian motion in the sense of finite dimensional distributions. We figure out ACF function and estimate the self-similarity parameter H of FARIMA(0, d, 0) by using R/S method. Finally, we display power spectrum density of FARIMA process.

• Journal of the Korean Institute of Telematics and Electronics
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• v.26 no.8
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• pp.1187-1196
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• 1989

In this paper, a method for computing the capacitance parameter for a multi-interconnection line in a multilayered dielectric region is presented. The number of interconnection lines and the number of dielectric layers are arbitrary, and the interconnection lines are finite cross section or infinite cross section. The surface of lines and dielectric interface are divided into subsection. The surface charge density of each subsection is a constant step-pulse function for each subsection. After the solution of surface charge density is effected by the method of moments, capacitance parameter is calculated.

• Journal of the Korean Data and Information Science Society
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• v.3 no.1
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• pp.25-31
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• 1992

Some results relating to $C_{0}(R)\;and\;L^{1}(R)$ spaces with application to kernel density estimators will be introduced. First, random elements in $C_{0}(R)\;and\;L^{1}(R)$ are discussed. Then, complete convergence limit theorems are given to show that these results can be used in establishing uniformly consistency and $L^{1}$ consistency.