• 한국해양공학회:학술대회논문집
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• 한국해양공학회 2002년도 추계학술대회 논문집
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• pp.301-306
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• 2002

The characteristics of parameters for the probability distribution of fatigue crack growth lives by the non-Gaussian random process simulation method is investigated. In this paper, the material resistance to fatigue crack growth is treated as a spatial random process, which varies randomly on the crack surface. Using the previous experimental data, the crack length - the number of cycles curves are simulated. The results are obtained for constant stress intensity factor range conditions with stress ratio of R=0.2, three specimen thickness of 6, 12 and 18mm, and the four stress intensity level. The probability distribution function of fatigue crack growth lives seems to follow the 3-parameter Wiubull and shows a slight dependence on specimen thickness and stress intensity level. The shape parameter, ${\alpha}$, does not show the dependency of thickness and stress intensity level, but the scale parameter, ${\beta}$, and location parameter, ${\upsilon}$, are decreased by increasing the specimen thickness and stress intensity level. The slope for the stress intensity level is larger than the specimen thickness.

• 한국자기학회지
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• 제21권2호
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• pp.52-55
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• 2011

스핀전달토크는 나노구조에서 자성상태를 제어하는데 유용한 수단이다. 자기터널접합에서 스핀전달토크는 자성물질층의 자화가 이루는 평면에 평행한 성분과 수직인 성분으로 나눌 수 있다. 이중 평행한 성분의 스핀전달토크의 성질은 상당히 잘 알려져 있으나, 수직인 성분의 스핀전달토크의 성질에 대해서는 여전히 이견이 많다. 비대칭 자기터널접합에서의 최근 실험에서, 수직전달토크의 전압 의존성이 전압의 이차항 성분뿐만 아니라 일차항 성분도 가짐을 보고하였다. 하지만 물질 변수에 대한 의존성은 여전히 잘 알려지지 않았다. 이 논문에서는 비대칭 자기터널접합에서의 스핀전달토크의 전압의존성을, 강자성층의 스핀 갈라짐 에너지와 일함수의 차이, 그리고 페르미 에너지를 변화시켜 가면서 체계적인 조사를 하였다.

• Communications for Statistical Applications and Methods
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• 제9권3호
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• pp.649-663
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• 2002

We consider an unlimited fluid queueing model which has Fractional Brownian motion(FBM) as an input and a single server of constant service rate. By using the result of Duffield and O'Connell(6), we investigate the asymptotic tail-distribution of the stationary work-load. When there are multiple homogeneous FBM inputs, the workload distribution is similar to that of the queue with one FBM input; whereas for the heterogeneous sources the asymptotic work-load distributions is dominated by the source with the largest Hurst parameter.

• 한국자기학회:학술대회 개요집
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• 한국자기학회 2009년도 임시총회 및 하계학술연구발표회
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• pp.159-160
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• 2009

• 한국환경보건학회지
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• 제24권2호
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• pp.145-150
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• 1998

This study was carried out to investigate the loss amount of collection at the different of precipitatation time, high voltage and gas speed. This work has focused on the dependence of the collection efficiency in the collector zone with gas speed and high voltage. This advanced Model is developed by research of the different parameter as the conventionnal modem of study. In order to investigate collection efficiency of electrostatic precipitator, the loss amount of knocking was measured with Monitek-Treubung and the particle size was analyzed by He-Ne laser diffraction spectroscopy.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.574-583
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• 2008

FBG(Fiber Bragg grating)s have shown a great potential for sensing applications, and are easily embedded in materials with a negligible impact on the mechanical properties of the host. However, the use of FBG sensors is limited by their simultaneous dependence on strain and temperature, thus only one parameter can be determined from a single grating. This paper reviews various methods to discriminate between strain and temperature effects. To overcome this cross sensitivity using only embedded optical fibers, a number of techniques have been proposed, most of them relying on the deconvolution of two simultaneous measurements.

• 천문학회보
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• 제38권2호
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• pp.55.2-55.2
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• 2013

We examine the effect of environment on star formation activity of a sample of a galaxy group catalogue constructed from the Sloan Digital Sky Survey(SDSS DR8) given in Tempel et al.(2012). As an environmental parameter, we use the richness of the galaxy group. According to this parameter, we select 6846 galaxies in dense environment and 297335 galaxies in low environment. By comparing the two samples, we identify the different relationship between star formation rate and stellar mass. In order to compare galaxies in different environment, we fixed other parameters(color, apparent magnitude), which can affect star formation efficiency except for stellar mass. Also, based on HI mass from the ALFALFA survey, we study the environmental dependence of Kennicutt-Schmidt law which show the correlation between star formation rate and gas content.

• Communications for Statistical Applications and Methods
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• 제24권5호
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• pp.481-492
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• 2017

This paper investigates a convergence rate of a test statistics given by two scale sampling method based on $A\ddot{i}t$-Sahalia and Jacod (Annals of Statistics, 37, 184-222, 2009). This statistics tests for longitudinal data having the existence of long memory dependence driven by fractional Brownian motion with Hurst parameter $H{\in}(1/2,\;1)$. We obtain an upper bound in the Kolmogorov distance for normal approximation of this test statistic. As a main tool for our works, the recent results in Nourdin and Peccati (Probability Theory and Related Fields, 145, 75-118, 2009; Annals of Probability, 37, 2231-2261, 2009) will be used. These results are obtained by employing techniques based on the combination between Malliavin calculus and Stein's method for normal approximation.

• 대한기계학회논문집A
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• 제27권6호
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• pp.914-922
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• 2003

In this paper, the strain localization of voided ductile material has been analyzed by nonlocal plasticity formulation in which the yield strength not only depends on an equivalent plastic strain measure (hardening parameter), but also on the Laplacian thereof. The gradient terms in yield criterion show an important role on modeling strain-softening phenomena of material. The influence of the mesh size on the elastic -plastic deformation behavior and the effect of the characteristic length parameter for localization prediction are also investigated. The proposed nonlocal plasticity shows that the load -strain curves converge to one curve. Results using nonlocal plasticity also exhibit the dependence of mesh size is much less sensitivity than that for a corresponding local plasticity formulation.

• 한국정밀공학회지
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• 제6권3호
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• pp.32-45
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• 1989

The positioning accuracy of robots depends upon a forward kinematics which relates the joint variables to the orientation and position of the robot extremity in the absolute coordinate system. The relationship between two connective joint coordi- nates of a robot, which is the basis of the kinematics, is defined by 4 Denavit-Hartenberg parameters. But manufacturing errors in machining and assembly process of robots lead to disctrepancies between the design parameters and the physical structure. Thus, improving the positioning accuracy of robots reguires the identification of the actual link parameters of each robot. In this study, the least-squares method is used to calibrate the link parameters and off-line parameter calibration software is developed. Computer simulation is done to study the dependence of the calibration performance upon the DOF of the robot and number of acquired data set used in the least-squares method. 3 DOF Robot/Controller and specially designed 3D coordinate measurer is made and experiment is carried out to verify the theoretical and computational analysis.