• 한국안전학회지
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• 제25권1호
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• pp.65-71
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• 2010

In this study, a series of finite element analysis using LUSAS were performed in order to assess the quantitative effects of repair and retrofit of stringer in steel plate girder railway bridge with fatigue cracks. And cutoff types of end part of upper flange were considered as right-angled type and round-angled type. Also, as a method of repair and retrofit of fatigue cracks in stringer, perforation of stop-hole and installation of bracket were considered. From the analysis result, it was possible to assess the fatigue safety and fatigue life of stringer with fatigue cracks, and to estimate the stress intensity factor range in cut-off part of stringer using J-integral method. Also, according to the method of perforation of stop-hole and installation of bracket, it was possible to calculate the crack propagation life at the cut-off part of stringer.

• Kyungpook Mathematical Journal
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• 제19권2호
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• pp.237-239
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• 1979

No matter how one chooses the major arcs in the decomposition of $[x_0,\;x_0+1]$ it is always true with regard to the union, m(n), of the corresponding minor arcs that the integal of $f^2(x,\;n)$ e(-nx) over m(n) is $O(nlog^{-1}n)$. Consequently, to establish a proof of the asymptotic formulation of Goldbach's conjecture one might be tempted to take this fact as a starting point and to then concentrate the attact on trying to obtain the requisite estimate on the integral of $f^2(x,\;n)$ e(-nx) over M(n), the union of a suitably chosen family of major arcs. In this paper I show that this approach is not possible.

• 천문학회보
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• 제39권2호
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• pp.65.1-65.1
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• 2014

We present Palomar/SWIFT integral field spectroscopy of z~0.2 strong $H{\alpha}$ emitters identified in the Sloan Digital Sky Survey. The large Halpha equivalent widths as well as the huge specific star formation rates of these galaxies are comparable with that of z>4 Lyman break galaxies, thus understanding the gas kinematics and the distribution of massive stars in these systems will help to obtain a better understanding of high-redshift star forming environments and the growth of massive galaxies. We measure the velocity dispersion across the entire galaxy, estimate the number density and the spatial distribution of massive stars from the emission line morphologies. The role of minor mergers in powering star formation is investigated as an alternative to cold flow driven star formation.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1995년도 Proceedings of the Korea Automation Control Conference, 10th (KACC); Seoul, Korea; 23-25 Oct. 1995
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• pp.95-98
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• 1995

In this paper, an unknown-input proportional integral (PI) observer is presented and its applicability to the design of exact loop transfer recovery (Exact LTR) is shown. First, a sufficient condition for the PI observer to estimate the states of systems without knowledge of unknown input is derived. A simple existence condition of the observer is given. Under the conditions, the Exact LTR with specified observer's poles is achieved by the unknown-input PI observer.

• 한국정밀공학회지
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• 제15권1호
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• pp.43-50
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• 1998

The purpose of the paper is to protect the damage of plastic IC package with searching the cause of the fracture due to the delamination and crack when the encapsulant of plastic IC package is on viscoelastic behavior with the effect of creep on high temperature, The model for analysis is the plastic SOJ package with dimpled diepad in the IR soldering process of surface mounting technology. The risk of delamination with calculating the distribution of viscoelastic thermal stress in the package without the crack in the surface mounting process is checked. The package model with the perfect delamination between chip and diepad is chosen to estimate the resistance against fracture in thermal loading with calculating C (t)-integrals according to the change of the design. The optimum design to depress the delamination and crack is presented.

• 대한수학회논문집
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• 제23권2호
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• pp.269-277
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• 2008

Let $f=(f_n)$ be a nonnegative submartingale such that ${\parallel}f{\parallel}{\infty}{\leq}1\;and\;g=(g_n)$ be a martingale, adapted to the same filtration, satisfying $${\mid}d_{gn}{\mid}{\leq}{\mid}df_n{\mid},\;n=0,\;1,\;2,\;....$$ The paper contains the proof of the sharp inequality $$\limits^{sup}_ n\;\mathbb{E}{\Phi}({\mid}g_n{\mid}){\leq}{\Phi}(1)$$ for a class of convex increasing functions ${\Phi}\;on\;[0,\;{\infty}]$, satisfying certain growth condition. As an application, we show a continuous-time version for stochastic integrals and a related estimate for smooth functions on Euclidean domain.

• 대한기계학회논문집
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• 제17권1호
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• pp.215-222
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• 1993

본 연구에서는 판 스프링의 길이가 두께에 비하여 비교적 큰 것을 고려하여 판스프링의 기하학적 치수와 물성치들을 이용하여 판스프링의 강성과 조립된판 스프링 집합체의 강성을 예측할 수 있는 방법을 본 이론과 변형률 에너지이론을 적용하여 개 발하였고 그 개발된 방법으로 구한 강성예측치와 특성실험에서 얻은 강성치를 비교, 분석하여 판 스프링 강성해석 방법의 신뢰성을 보임과 동시에 독자적인 홀드다운스프 링 집합체의 특성해석 방법을 제시 하였다.

• 한국산업융합학회 논문집
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• 제2권2호
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• pp.131-137
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• 1999

Package crack caused by the soldering process in the surface mounting plastic package is evaluated by applying the energy release rate criterion. The package crack formation depend on various parameters such as chip set, chip size, package thickness, package width, material properties and the moisture content etc. The effects of chip set and the other parameters were estimated during the analysis of package cracks which were located in the edge of the upper interface of the chip and the lower interlace of the die pad. From the results, it could be obtained that the more significant parameters to effect the chip set are chip width.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1998년도 하계학술대회 논문집 A
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• pp.64-66
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• 1998

This paper presents a new efficient method for transient analysis in magnetodynamic systems of linear eddy current problems. This mehtod employs the Fourier transform and the high-order frequency sensitivity of harmonic finite element method. By taking into account the time-constant of magnetodynamic system, the Fourier integral of continuous frequency is converted into the Fourier series of discrete frequency. And with the results of Fourier series expansion of converted input wave form, the responses of each sinusoids is superposed to give the total response of the magnetodynamic systems. But, if the frequency band of input wave form is broad, it takes long computational time since all responses for each sinusoids must be calculated. Therefore, the high-order frequency sensitivity method is employed to estimate the response variation to frequency. The proposed algorithm is applied to an induction heating system to validate its numerical efficiency.

• 대한인간공학회지
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• 제16권2호
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• pp.1-14
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• 1997

In conventional probability-based human reliability analysis, the basic human error rates are modified by experts to consider the influences of many factors that affect human reliability. However, these influences are not easily represented quantitatively, because the relation between human reliability and each of these factors in not clear. In this paper, the relation is expressed quantitatively. Furthermore, human reliability is represented by error possibilities proposed by Onisawa, which is a fuzzy set on the interval [0,1]. Fuzzy reasoning is used in this method in order to obtain error possibilities. And, it is supposed that many basic events affected by the above factors are connected to the top event through Fault Tree structure, and an estimate of the top event expressed by a member- ship function is obtained by using the fuzzy measure and fuzzy integral. Finally, a numerical example of human reliability analysis obtained by this method is given.