• Transactions of the Korean Society of Mechanical Engineers
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• v.10 no.6
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• pp.814-822
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• 1986

Flow patterns and its transitions in vertical two phase flow of air-water isothermal flow are identified objectively by void output signals and moments computed from the Probability Density Function which is associated with the statistical measurement for time average local void fractions using conductance probe. It has been shown that the probe output signals, PDF distributions and its moments are deterministic criteria of flow pattern and transition classification.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.2
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• pp.492-501
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• 1994

This study is an analysis of the turbulent diffusion flame with swirl flow and the calculated results are compared with experimental data in case of various swirl numbers and air-fuel rations. The mathematical model is restricted to single-phase, diffusion controlled combustion with swirl flow. Values of local flow properties were obtained by solving appropriate differential equation for continuity, momentum, stagnation enthalpy, concentration, turbulence energy, dissipation rate of turbulence energy, and the mean square of concentration fluctuation. The method is proposed for calculating the local probability of chemical reaction based on the use of the probability density function for the mixture fraction.

• Journal of the Korean Statistical Society
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• v.9 no.1
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• pp.31-38
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• 1980

The problem considered in this paper can be defiened as follows. Consider observations $x_1, x_2, \cdot, x_n$ which are assumed to come from a mixed population of the density function, $$f(x) = \sum^m_{k=1} pkf_k(x)$$ where m is the number of subpoulations and $p_k$ is the proportion of subpopulation k such that $\sum^m_{k=1} pk=1, 0

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.1A
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• pp.48-55
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• 2000

In this paper, an assumption to design a quantizer, is proposed that if one small region of a probability density function is represented larger probability and bigger total error than another neighbour region, then the quantizer is not optimal. It is tested when the probability functions are Gaussian, Laplacian and uniform density function by the computer simulations. A new LBG algorithm which originates from this assumption in addition to LBG algorithm, is designed for the vector quantizer. The new LBG algorithm presents better performance than the original LBG algorithm in the average error and the variance of the error.

• Journal of Korean Society on Water Environment
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• v.24 no.4
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• pp.430-435
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• 2008

In order to design Non-point source management, the aspect of statistical features of the entire precipitation data should be focused since non-point source discharge is driven by continuous rainfall runoffs. 3-parameter mixed exponential probability density function is used to establish urban stormwater capture curve instead of previous single-parameter exponential PDF. Then, recent 10-year data in Busan are applied to establish the curve. The result shows that 3-parameter mixed PDF gives better resolution.

• Journal of the Korea Institute of Military Science and Technology
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• v.12 no.1
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• pp.1-7
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• 2009

Tracking and detecting targets by the M/W seeker is affected by the clutter reflecting from the earth's surface. In order to detect the look-down retreating targets, which appear in the sidelobe clutter region, in the M/W seeker of High PRF mode, it is necessary to understand statistical characteristics of the surface sidelobe clutter. Statistical analysis of sidelobe clutter is conducted for several configurations of the surface using data obtained by the CFT (Captive Flight Test) of the M/W seeker in High PRF mode. The probability density function(PDF) fitting is conducted for several configuration and conditions of the surface. PDFs and PDF parameters, which best describe statistical distribution of sidelobe clutter, are estimated.

• Structural Engineering and Mechanics
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• v.3 no.2
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• pp.135-144
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• 1995

Since structural systems may fail in any one of several failure modes, computation of system reliability is always difficult. A method using numerical quadrature for computing structural system reliability with either one or more than one failure mode is presented in this paper. Statistically correlated safety margin equations are transformed into a group of uncorrelated variables and the joint density function of these uncorrelated variables can be generated by using the Maximum Entropy Method. Structural system reliability is then obtained by integrating the joint density function with the transformed safety domain enclosed within a set of linear equations. The Gaussian numerical integration method is introduced in order to improve computational accuracy. This method can be used to evaluate structural system reliability for Gaussian or non-Gaussian variables with either linear or nonlinear safety boundaries. It is also valid for implicit safety margins such as computer programs. Both the theory and the examples show that this method is simple in concept and easy to implement.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.4
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• pp.161-168
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• 2009

The most generalized form of the triadic operating policy for an M/G/1 queueing model is developed. It consists of three simple N, T and D operating policies and has a peculiar structure possessing concepts of dyadic policies. Using the concept of the pseudo probability density function of the busy period, its expected busy period for the controllable M/G/1 queueing model is derived. Since the obtained result is the most generalized form the triadic polity, the expected busy periods for all known dyadic policies are recovered as special cases from it.

• Journal of the military operations research society of Korea
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• v.25 no.1
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• pp.55-74
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• 1999

In this study, a nonsymmetric model of directional probability variation (dpv), which is fundamental and conforms well to various moving situations of attacking tanks, is obtained based on the Whittaker's theory. It is shown that it produces the same expression of the probability density function as the Whittaker's under the special moving condition of an attacking tank. Using the derived dpvs, the probability densities for the various cases of some examples are calculated numerically to verify the derived formulas, and compared with other existing symmetrical distributions widely used to grasp characteristics of them. As a result, it is noted that the plots of the probability density function for various cases selected exhibit very different and useful behavioral features. Applying the results with respect to the every tank in the computer simulation of engagement between two tank forces, it is expected that more reasonable shot distributions can be given comparing with other existing symmetrical ones. The derived dpvs may be utilized to decide shot distribution of other weapon systems through small modification.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.41 no.5
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• pp.492-501
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• 1992

In this paper, an ion analyzer is used in conjunction with a Langmuir probe to study the chracteristics of ECR plasma such as the ion temperature, ion current density and electron temperature as the operating pressure, ${\mu}$-wave power and axial position change, Silicon etching has been performed with RF-biasing and its etching chracteristics have been discussed in terms of the ion energy distribution function. The maximum value of ion current density appears in the range of 10S0-3T mbar and the broadening of ion energy distribution function increases as pressure increases. Therefore, as pressure decreases, anisotropy increases but selectivity to photoresist decreases.