• Journal of Communications and Networks
• /
• v.6 no.3
• /
• pp.209-215
• /
• 2004

In this paper, a butterfly Log-MAP decoding algorithm for turbo code is proposed. Different from the conventional turbo decoder, we derived a generalized formula to calculate the log-likelihood ratio (LLR) and drew a modified butterfly states diagram in 8-states systematic turbo coded system. By comparing the complexity of conventional implementations, the proposed algorithm can efficiently reduce both the computations and work units without bit error ratio (BER) performance degradation.

• 전기의세계
• /
• v.22 no.2
• /
• pp.51-56
• /
• 1973

The comparative study of maximum likelihood estimation with Bayesian approach was made by statistical & computational methods in center of a priori information of static systems and the effect of a priori information on the accuracy of the estimatiion was also analyzed. Through the numerical computations of some examples by digital computer, we concluded that maximum likelihood method is better than Bayesian estimation except for almost certain a priori informations. The study may therefore contribute in identification problems of dynamical systems connected with a priori informations.

• 한국연소학회:학술대회논문집
• /
• 2012.04a
• /
• pp.279-281
• /
• 2012

A short chemical mechanism was developed with the chemical model reduction strategy based on the use of Simulation Error Minimization Connectivity Method(SEM-CM). We examined the accuracy resulting from using this mechanism, as compared with the full mechanism, for premixed flames and auto-ignition of methane-air mixture under high pressures. These comparisons are in good agreement, but it has a little divergence to predict the ignition delay time at high pressure conditions as compared with experiment results.

• Journal of the Korean Operations Research and Management Science Society
• /
• v.21 no.2
• /
• pp.49-58
• /
• 1996

The generalized Erlang loss function, extensively studied in the literature, is revisited. We study the steady state loss probability in M/M/s/s + c queueing system and prove that it satisfies the first and second order properties in integral number of servers as well as integral queue capacities. Also we study the problem of allocating integral number of servers and queue capacities, and develop an algorithm to obtian an optimal allocation of them individually and jointly with the small number of computations.

• Korean Journal of Mathematics
• /
• v.7 no.2
• /
• pp.245-269
• /
• 1999

Multigrid method and acceleration by conjugate gradient method for first-order system least squares (FOSLS) using bilinear finite elements are developed for various boundary value problems of planar linear elasticity. They are two-stage algorithms that first solve for the displacement flux variable, then for the displacement itself. This paper focuses on solving for the displacement flux variable only. Numerical results show that the convergence is uniform even as the material becomes nearly incompressible. Computations for convergence factors and discretization errors are included. Heuristic arguments to improve the convergences are discussed as well.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 1996.10a
• /
• pp.185-191
• /
• 1996

The Variation of die bearing is primary way to control the metal flow in hot square die extrusion process. Finite element computations are carried out to assess the influence of die bearing on metal flow and state variables. The finit element method is developed based on ALE description for a rigid-viscoplastic material. Since thermal state computational example, hot square die extrusion with varied die bearing lengths has been analyzed for the profile of a L-section.

• 한국해양학회지
• /
• v.15 no.2
• /
• pp.112-122
• /
• 1980

A two-dimensional non-linear tidal model has been established to calculate the M$\_$2/ tide of Inchon Bay in the west coast of Korea. Cartesian coordinates are used for the derivation of the governing equations and account is taken of extensive drying boundaries (tidal flats) which are exposed at low tides. The tidal amplitudes and phases computed from the model agree well with those known from observation lying within bounds 5cm in amplitude and 5 in phase relative to the observed results. The work represents a further stage in the development including extensive sea measurements capable of application in various coastal engineering problems encountered in Inchon Bay area.

• Magazine of the Korean Society of Agricultural Engineers
• /
• v.14 no.1
• /
• pp.2557-2569
• /
• 1972

Hydraulic computations to determine the elevation of canal bottom and mater surface for box type concrete culverts are discussed. Velocity and cross sectional area of flow are computed from Manning's formula. Aad then head loss and velocity head are considered to determine the elevation of bottom and water surface. For stress analysis, 13.5 ton live load and earth pressure are considered. Also longitudinal stress of box culverts is checked.

• Journal of the Korean Statistical Society
• /
• v.31 no.1
• /
• pp.45-61
• /
• 2002

We consider the problem of estimating binomial proportions in the presence of nonignorable nonresponse using the Bayesian selection approach. Inference is sampling based and Markov chain Monte Carlo (MCMC) methods are used to perform the computations. We apply our method to study doctor visits data from the Korean National Family Income and Expenditure Survey (NFIES). The ignorable and nonignorable models are compared to Stasny's method (1991) by measuring the variability from the Metropolis-Hastings (MH) sampler. The results show that both models work very well.

• Journal of the Korean Statistical Society
• /
• v.9 no.1
• /
• pp.97-108
• /
• 1980

Variance components model appears often in designing experiments including time series data analysis. This paper is investigating the properties of the various procedures in estimating variance components for the two-way random model without interaction under normality. In this age of computer-oriented computations, MINQUE is found to be quite practicla because of the robustness with respect to the design configurations and parameters. Also adjusted AOV type estimation procedure is found to yield superior results over the unadjusted one.