• Journal of the Korean Data and Information Science Society
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• v.10 no.1
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• pp.135-146
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• 1999

In this paper, we consider the Bayesian hypotheses testing for independence and symmetry in Freund's bivariate exponential model. In Bayesian testing problem, we use the noninformative priors for parameters which are improper and are defined only up to arbitrary constants. And we use the recently proposed hypotheses testing criterion called the intrinsic Bayes factor. Also we derive the arithmetic and median intrinsic Bayes factors and use these results to analyze some data sets.

• The Transactions of the Korean Institute of Power Electronics
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• v.3 no.1
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• pp.70-76
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• 1998

A switch-mode AC/DC converter with high input power factor and sinusoidal input current waveforms is analyzed and modelled for computer simulation. The developed mathematical model for this converter can be used to examine the transient and steady-state performance for selecting the proper ratings of filter, boost inductor and semiconductor devices or the effects of this converter under normal and fault operating conditions on the associated power systems. The proposed model and computer programs are confirmed by comparing with the experimental results.

• Geomechanics and Engineering
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• v.11 no.5
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• pp.691-711
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• 2016

In this study, the uplift capacity of anchor plates embedded in sand was investigated by conducting model tests. Square shaped anchors were used in the tests and parameters such as relative density of sand, embedment ratio (H/B), spacing ratio between anchors (S/B) and anchor configuration affecting the uplift capacity were investigated. Breakout factor and group efficiency which are dimensionless parameters were used to show the results. A series of finite element analyses and analytical solutions were additionally performed to ascertain the validity of the findings from the laboratory model tests and to supplement the results of the model tests. It can be concluded that the embedment depth in dense sand soil condition is the most important parameter with respect to the other parameters as to influencing the uplift capacity of group anchors.

• Journal of Applied Reliability
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• v.6 no.1
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• pp.37-50
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• 2006

The accelerated life tests of the catalytic gas sensor were performed at three different gas concentration conditions. From the test data, the power-Weibull model was estimated and the acceleration factor between test condition 25%LEL(Lowe Explosive Limit) and use condition 5%LEL was about 3 according to this acceleration model. Using this acceleration factor, life test specification for qualifying that B10 lifetime of the catalytic gas sensor meets the goal lifetime (5 years) was designed.

• International Journal of Air-Conditioning and Refrigeration
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• v.8 no.1
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• pp.40-49
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• 2000

The capillary tube performance for R-407C is experimentally investigated. The experimental setup is a real vapor-compression refrigerating system. Mass flow rate is measured for various diameter and length while inlet pressure and degree of subcooling are changed. These data are compared with the results of a numerical model. The mass flow rate of the numerical model is about 14% less than the measured mass flow rate. It is found that mass flow rate and length for R-407C are less than those for R-22 under the same condition. Based on this experimental study and the numerical model, a set of design charts for capillary tube of R-407C is proposed.

• Journal of the Korean Institute of Intelligent Systems
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• v.12 no.3
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• pp.255-260
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• 2002

This paper describes a fuzzy-based system for analyzing the stress intensity factors (SIFs) of three-dimensional (3D) cracks. A geometry model, i.e. a solid containing one or several 3D cracks is defined. Several distributions of local node density are chosen, and then automatically superposed on one another over the geometry model by using the fuzzy knowledge processing. Nodes are generated by the bucketing method, and ten-coded quadratic tetrahedral solid elements are generated by the Delaunay triangulation techniques. The singular elements such that the mid-point nodes near crack front are shifted at the quarter-points, and these are automatically placed along the 3D crack front. The complete finite element(FE) model is generated, and a stress analysis is performed. The SIFs are calculated using the displacement extrapolation method. To demonstrate practical performances of the present system, semi-elliptical surface cracks in a inhomogeneous plate subjected to uniform tension are solved.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.3 no.2
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• pp.146-155
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• 2002

Surface complexation models employ mass law equations to describe the reaction of surface functional groups with ions in the solution and also Gouy-Chapman theory to consider the electrostatic effects in the surface reactions. In current surface complexation models, however, the coulombic factors used are not wholly consistent with the Gouy-Chapman model of the surface. This study was to provide the derivation of the coulombic term usually employed and then a revised coulombic term completely consistent with Gouy-Chapman Theory. The electrical potential energy. zF${\psi}$, in current surface complexation models is not consistent with the Gouy-Chapman theory with the potential gradient close to the charged surface but with the Donnan model with the uniform potential. Even though the new coulombic factor yielded lower surface potential, it provided worse fits for acid-base titration data of the goethite suspensions.

• Proceedings of the KIEE Conference
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• 2007.07a
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• pp.290-291
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• 2007

Barometers can provide height information steady but its accuracy becomes poor as the air data varies due to the vehicles's moving or time's elapsing. In order to keep the accuracy in spite of the air data changes, we propose a filter for the identification of baro-errors. The baro-errors mainly consist of bias and scale factor errors which gradually varies as the air data varies. With GPS height measurements, the scale factor and bias estimator is designed by applying the interacting multiple model (IMM) filtering technique to the baro-error random walk model. The resultant estimates are used to compensate current baro-measurement to supply accurate measurements steadily.

• Journal of Korean Society for Quality Management
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• v.33 no.2
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• pp.1-12
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• 2005

An extensive literature review has been made in this paper to build the evaluation hierarchy structure for the certification of electronic commerce services. In building the evaluation hierarchy structure, major candidate evaluation factors are selected by bench marking the various certification practices, including the Malcolm Baldrige award, ISO9000, and BSC(balanced scorecard) techniques. This paper deployed principal component analysis and factor analysis techniques to develop a statistically solid and systematic evaluation model. The final evaluation model, as presented in this paper as a model for the certification of electronic commerce services, produces a numeric score on the 100% scale, which can be served as a metric for the certification decision. The AHP technique was used in converting the various qualitative and quantitative evaluation values into a single measure for the certification decision.

• Proceedings of the KIPE Conference
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• 2015.11a
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• pp.209-210
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• 2015

This paper presents a new model predictive control method without the effect of a weighting factor in order to reduce common-mode voltage (CMV) for a three-phase voltage source inverter (VSI). By utilizing two active states with same dwell time during a sampling period instead of one state used in conventional method, the proposed method can reduce the CMV of VSI without the weighting factor. Simulation is carried out to verify the effectiveness of the proposed predictive control method with the aid of PSIM software.