• Journal of the Korean Wood Science and Technology
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• v.37 no.2
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• pp.141-147
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• 2009

The fluctuation of physical properties in wood or wood composites is an important subject when the materials in building and construction. Sorption and desorption occur in wood when exposed to the open air, and the temperature distribution in wood can fluctuate as a result of changes in environmental temperature, solar radiation, humidity, and wind velocity. In this study, the temperature difference and fluctuation caused by outdoor environment among different wood species were analyzed using a numerical method. The effect on the process of heat transfer in wood caused by environmental factors was investigated using 1-dimensional partial differential equation with real boundary and initial conditions. The experimental data have been used to check the accuracy of programming code. Through analysis, it was found out that density and moisture content have a negative effect on thermal diffusivity of wood.

• Journal of the Korean Data and Information Science Society
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• v.25 no.2
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• pp.431-438
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• 2014

Type I hybrid censoring scheme is the combination of the Type I and Type II censoring scheme introduced by Epstein (1954). Epstein considered a hybrid censoring sampling scheme in which the life testing experiment is terminated at a random time $T^*$ which is the time that happens rst among the following two; time of the kth unit is observed or time of the experiment length set in advance. The likelihood function of this scheme from the Rayleigh distribution cannot be solved in a explicit solution and thus we approximate the function by the Taylor series expansion. In this process, we propose four dierent methods of expansion skill.

• Proceedings of the KIEE Conference
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• 1995.11a
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• pp.395-397
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• 1995

To investigate the effects of solvent extraction on electrical properties of LDPE, charge distribution, electrical conduction, and FT-IR experiments are carried out for three kinds of LDPE which are same for melt index (MI) and density. The effects of short chains for the charge distribution are quite different. For the electrical conduction, the electrical conduction mechanism remains unchanged, as the solvent extraction temperature is increased.

• Wind and Structures
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• v.31 no.4
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• pp.311-319
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• 2020

India is a developing nation and heavily spends on the development of wind power plants to meet the national energy demand. The objective of this paper is to investigate wind power potential of Ennore site using wind data collected over a period of two years by three parameter Weibull distribution. The Weibull parameters are estimated using maximum likelihood, least square method and moment method and the accuracy is determined using R² and root mean square error values. The site specific capacity factor is calculated by the mathematical model developed by three parameter Weibull distribution at different hub heights above the ground level. At last, the wind energy economic analysis is carried out using capacity factor at 30 m, 40 m and 50 m height for different wind turbine models. The analysis showed that the site has potential to install utility wind turbines to generate energy at the lowest cost per kilowatt-hour at height of 50 m. This research provides information of wind characteristics of potential sites and helps in selecting suitable wind turbine.

• Bulletin of the Korean Mathematical Society
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• v.33 no.4
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• pp.545-551
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• 1996

It is well known in the theory of distributions and proved in [GS, S] that $$ (i) (Bochner-Schwartz) Every positive definite (tempered) distribution is the Fourier transform of a positive tempered measure \mu. $$ $$ (ii) (Schwartz kernel theorem) Let B(\varphi, \psi) be a bilinear distribution. Then for some u \in D'(R^n \times R^n) B(\varphi, \psi) = u(\varphi(x)\bar{\psi}(y)) for every \varphi, \psi \in C_c^\infty. $$ $$ (iii) A translation invariant positive definite bilinear distribution B(\varphi, \psi) is of the form B(\varphi, \psi) = \smallint \varphi(x)\psi(x) d\mu(x) for every \varphi, \psi \in C_c^\infty (R^n), where \mu is a positive tempered measure.

• Proceedings of the KIPE Conference
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• 1998.10a
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• pp.246-251
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• 1998

This paper describes the main features of an unconventional tester for high power semiconductor devices. Two application ranges are highlighted. The tester is used for the extraction of GTO parameters and their verification by measurements. The second field comprises the determination of the radial and azimuthal current density distribution of a GTO tablet. The results are compared with the carrier lifetime distribution.

• Journal of Surface Science and Engineering
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• v.29 no.6
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• pp.728-734
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• 1996

To obtain the relation in the electrochemical reduction of $CO_2$ in aqueous $KHCO_3$ colution between an activity for the product and the nature of Cu electrode, the electrode surface was characterized by using two methods: X-ray photoelectron spectroscopy (XPS) and photoelectron emission (PE) measurement. Electrolyses were performed with Cu electrodes pretreated in several ways. The distribution of the products changed drastically with electrolysis time and the pretreatment method. The features in XPS spectra were closely connected with the product distribution. The oxide film at the electrode surface was gradually reduced to bare Cu metal with electrolysis time, resulting in a variation of the product distribution. PE was measured by verying the wavelength of incident light at several temperatures. The dependence of PE on the measurement temperature changed greatly before and after electrolysis.

• Communications for Statistical Applications and Methods
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• v.23 no.2
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• pp.119-129
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• 2016

A new sampling method is introduced based on the idea of a ranked set sampling scheme in which taken samples in each set are dependent on previous ones. Some theoretical results are presented and distribution-free confidence intervals are derived for the quantiles of any continuous population. It is shown numerically that the proposed sampling scheme may lead to 95% confidence intervals (especially for extreme quantiles) that cannot be found based on the ordinary ranked set sampling scheme presented by Chen (2000) and Balakrishnan and Li (2006). Optimality aspects of this scheme are investigated for both coverage probability and minimum expected length criteria. A real data set is also used to illustrate the proposed procedure. Conclusions are eventually stated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.11a
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• pp.47-55
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• 2003

This paper Presents active control algorithm using probability density function of structural energy. It is assumed that the structural energy under excitation has Rayleigh probability distribution. This assumption is based on the fact that Rayleigh distribution satisfies the condition that the structural energy is always positive and the occurrence probability of minimum energy is zero. The magnitude of control force is determined by the probability that the structural energy exceeds the specified target critical energy, and the sign of control force is determined by Lyapunov controller design method. Proposed control algorithm shows much reduction of peak responses under seismic excitation compared to LQR controller, and it can consider control force limit in the controller design. Also, chattering problem which sometimes occurs in Lyapunov controller can be avoided.

• Communications for Statistical Applications and Methods
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• v.20 no.1
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• pp.63-75
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• 2013

In this paper, we derive maximum likelihood estimators (MLEs) and approximate maximum likelihood estimators (AMLEs) of unknown parameters in a generalized half logistic distribution under Type-II hybrid censoring. We also obtain approximate confidence intervals using asymptotic variance and covariance matrices based on the MLEs and the AMLEs. As an illustration, we examine the validity of the proposed estimation using real data. Finally, we compare the proposed estimators in the sense of the mean squared error (MSE), bias, and length of the approximate confidence interval through a Monte Carlo simulation for various censoring schemes.