• Journal of Ocean Engineering and Technology
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• v.1 no.2
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• pp.83-92
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• 1987

Inorder ot estimate the running life of turbine rotors, fatigue crack propagation low, da/dN = C(${\DELTA}K)^m$, proposed by paris et al. has been widely applied. In this study, fatigue crack propagation rates for 16 samples of 1% Cr-Mo-V rotor steel were measured and statistical characteristics of m and C values in above equation were reviewed. The results are summarized as follows. 1. C and m follow a log-normal distribution and normal distribution, respectively. And the relation of C and shows a strong negative correlation. 2. Fatigue crack propagation equation can be expressed as da/dN=$4.11{\times}10^{-4}({\Delta}K/153.8)^m$, introducing the ralationship C=$C_oK_o^{-m}$. In this case, contribution of $C_o$ distribution to the distribution of log C shows very small compared to degrees of contribution by m.

• Proceedings of the KIEE Conference
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• 2000.07c
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• pp.1837-1839
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• 2000

This paper describes PD patterns in GIS recognized by using neural network proposed in this paper PD sources in GIS were classified by four states and PD signals were expressed by $\Phi-Q$ distribution, ${\Phi]-Q_m$ distribution, $\Phi-N$ distribution and Q-N distribution. Then statistical operators were extracted from each distributions. As a result, the PD pattern recognizing rate in GIS using neural network proposed in this paper was increased.

• Nuclear Engineering and Technology
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• v.49 no.1
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• pp.189-195
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• 2017

Gel dosimeters have unique advantages in comparison with other dosimeters. Until now, these gels have been used in different radiotherapy techniques as a reliable dosimetric tool. Because dose distribution measurement is an important factor for appropriate treatment planning in different radiotherapy techniques, in this study, we evaluated the ability of the N-isopropylacrylamide (NIPAM) polymer gel to record the dose distribution resulting from the mixed neutron-gamma field of boron neutron capture therapy (BNCT). In this regard, a head phantom containing NIPAM gel was irradiated using the Tehran Research Reactor BNCT beam line, and then by a magnetic resonance scanner. Eventually, the $R_2$ maps were obtained in different slices of the phantom by analyzing T2-weighted images. The results show that NIPAM gel has a suitable potential for recording three-dimensional dose distribution in mixed neutron-gamma field dosimetry.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.20 no.11
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• pp.959-964
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• 2007

To investigate the influence of partial discharge(PD) distribution characteristics due to various defects on the power cable joints interface, we used the K-means clustering method. As the result of PD number(n) distribution analyzing on $\Phi-n$ graph, the phase angle($\Phi$) of cluster centroid shifted to $0^{\circ}\;and\;180^{\circ}$ increasing with applying voltage. It was confirmed that the PD quantify(q) and euclidean distance of centroid were increased with applying voltage from the centroid distribution analyzing of $\Phi-q$ plane. The dispersion degree was increased with calculated standard deviation of the $\Phi-q$ cluster centroid. The PD number and mean value on $\Phi-q$ graph were some different by electric field concentration with defect types.

• ETRI Journal
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• v.10 no.4
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• pp.89-98
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• 1988

We consider an N duplicate-server system, where each server consists of two reconfigurable duplicated units which are subject to breakdowns. This system is studied analytically using generating functions, and also numerically using the matrix-geometric procedure. Using the generating function approach we obtain a recursive expression of the queuelength distribution for N=1. This expression in difficult to generalize to N>1. The numerical method is applicable for any value of N. For any N, we also obtain the condition for stability and the availability of the system.

• Bulletin of the Korean Mathematical Society
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• v.53 no.2
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• pp.365-371
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• 2016

Let f be a transcendental meromorphic function in the complex plane $\mathbb{C}$, and a be a nonzero constant. We give a quantitative estimate of the characteristic function T(r, f) in terms of $N(r,1/(f^2(f^{\prime})^n-a))$, which states as following inequality, for positive integers $n{\geq}2$, $$T(r,f){\leq}\(3+{\frac{6}{n-1}}\)N\(r,{\frac{1}{af^2(f^{\prime})^n-1}}\)+S(r,f)$$.

• Journal of applied mathematics & informatics
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• v.20 no.1_2
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• pp.119-132
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• 2006

This paper presents an approach for using right-truncated exponentially distributed random variables to model activity times in stochastic activity networks. The advantages of using the right-truncated exponential distribution are discussed. The moments of a project completion time using the proposed distribution are derived and compared with other estimated moments in literature.

• Journal of the Korean Data and Information Science Society
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• v.12 no.2
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• pp.27-33
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• 2001

Suppose that there is a population of hidden objects of which the total number N is unknown. From such data, we derive an asymptotic distribution for stopping time.

• Journal of the Korean Data and Information Science Society
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• v.10 no.2
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• pp.313-318
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• 1999

Suppose that there is a population of hidden objects of which the total number N is unknown. From such data, we derive an asymptotic distribution.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2009.04a
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• pp.300-303
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• 2009

The purpose of this study is to grasp the preference of colors in housing spaces by different type of personality and color preference by classifying dwellers various characteristics by MBTI to obtain basic informations for the color plan that satisfies their inner desire. The results of this study are as followed. Firstly, we could say about the color distribution of living spaces like that. The ceiling and general wall showed that N(white) systems and YR of bright tone was mostly distributed. The color of floor showed that the calm tone of YR was mostly distributed. Secondly, as for the favored colors of finishing material at each space, the biggest distribution of preference color was found as N(white) group(series) in case of ceilings. As for general walls, bright tone of N(white) group showed most in living rooms. In case of that of the floor, it showed the largest distribution of calm tone of YR. Point wall was preferred bright and brilliant in various kinds of color. Thirdly, as in favor of colors of closing materials, sensible types(S) are concentrated on common color groups, on the other hand, intuition types(N) prefer color groups of various kinds not only general preferred colors.