• Industrial Engineering and Management Systems
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• v.11 no.4
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• pp.390-396
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• 2012

The present paper extends the idea of tightened-normal-tightened sampling scheme to group acceptance sampling plans under the time truncated life tests. We consider three famous distributions that are widely used in the area of reliability such as the generalized exponential distribution, the Weibull distribution, and the Birnbaum-Saunders distribution in the proposed sampling plan. The plan parameters are determined such that the producer's risk and the consumer's risk are satisfied at the specified median life. Extensive tables showing plan parameters are provided at various values of the experiment time and the consumer's risk for each of three distributions for the practical use. Some examples are given to illustrate the procedure of the proposed plan.

• Structural Engineering and Mechanics
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• v.7 no.3
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• pp.259-276
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• 1999

An analytical solution for the shape functions of a beam segment supported on a generalized two-parameter elastic foundation is derived. The solution is general, and is not restricted to a particular range of magnitudes of the foundation parameters. The exact shape functions can be utilized to derive exact analytic expressions for the coefficients of the element stiffness matrix, work equivalent nodal forces for arbitrary transverse loads and coefficients of the consistent mass and geometrical stiffness matrices. As illustration, each distinct coefficient of the element stiffness matrix is compared with its conventional counterpart for a beam segment supported by no foundation at all for the entire range of foundation parameters.

• Proceedings of the Korean Nuclear Society Conference
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• 1996.05a
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• pp.40-45
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• 1996

A new concept of equivalent homogenization is proposed. The concept employs new set of homogenized parameters: homogenized cross sections (XS) and interface matrix (IM), which relates partial currents at the celt interfaces. The idea of interface matrix generalizes the idea of discontinuity factors (DFs), proposed and developed by K.Koebke and K.Smith. The method of K.Smith can be simulated within framework of new method, while the new method approximates heterogeneous cell better in case of the steep flux gradients at the cell interfaces. The attractive shapes of new concept are: improved accuracy, simplicity of incorporation in the existing codes, equal numerical expenses in comparison to the K.Smith's approach. The new concept is useful for: (a) explicit reflector/baffle simulation; (b) control blades simulation; (c) mixed UO2/MOX core simulation, The offered model has been incorporated in the finite difference code and in the nodal code PANBOX. The numerical results show good accuracy of core calculations and insensitivity of homogenized parameters with respect to in- core conditions.

• Journal of the Korean Geotechnical Society
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• v.20 no.5
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• pp.37-48
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• 2004

This study is focused on the constitutive model in order to represent brittleness and dilatancy for cohesionless soils. The constitutive model was based on an anisotropic hardening rule derived from generalized isotropic hardening nile, which includes an appropriate hardening equation for the overall strain behavior at small to large strains. The yield surface is a simple cylinder type in stress space and it makes the model practically useful. Hence dilatancy behavior in cohesionless soils could be modeled reasonably. A peak stress ratio was defined in order to model brittle stress-strain relationships. An optimized design methodology was proposed on the basis of real-coded genetic algorithm in order to determine parameters for the proposed model systematically. The material parameters were then determined by that algorithm. In order to verify the proposed model, triaxial tests were performed under $K_0$ conditions far weathered soils. In comparison with the triaxial test results under $K_0$ conditions, the proposed model could calculate appropriately the actual effective stress behavior on brittle stress-strain relationships and dilatancy.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.3 no.2
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• pp.48-62
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• 1985

A method for the free network adjustment is proposed, based on the application of generalized inverse matrix (g-inverse). If the network adjustment is executed according to the solution with parameters, especially when all coordinates are considered as parameters to keep unity strength, the matrix of normal equation will be singular. This paper discusses the problem of singular matrix and the analysis of accuracy between conventional method and the free network adjustment of trilateration. In case of the adjustment, the RMS errors of adjusted X, Y coordinates are increased to 35.6% in a polygon, central-point figure, and 50.5% in a quadrilateral. In the elements of error ellipse, the RMS errors are decreased by $\pm$24.5% (a) and $\pm$5.0 % (b) in the polygon, $\pm$42.6% (a) and $\pm$49.2% (b) in the quadrilateral. Introduction of free network adjustment, therefore, could be applied to improvement of relative accuracy in the horizontal positioning.

• Journal of Periodontal and Implant Science
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• v.43 no.2
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• pp.79-86
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• 2013

Purpose: The purpose of study was to compare glycemic control using glycated hemoglobin levels ($HbA_{1c}$) in diabetic patients with chronic generalized periodontitis (CGP) undergoing scaling and root planing (SRP) with and without systemic doxycycline. Methods: Fifty subjects with type 2 diabetes mellitus ($T_2DM$) and CGP receiving antidiabetic therapy were selected for study. The selected subjects were randomly assigned to two groups (test group [TG] and control group [CG]) comprising 25 patients each. The TG received SRP followed by systemic doxycycline. The CG received treatment with SRP only. The periodontal parameters were recorded at baseline (day zero), and every 1 month for 4 months and included probing depth, clinical attachment level, plaque index, gingival index, and $HbA_{1c}$ level were recorded at baseline (day zero) and at the end of 4 months. Results: A statistically significant effect was demonstrated for the periodontal parameters for both the TG and CG. $HbA_{1c}$ values did not show a statistically significant difference in the treatment group as compared to the CG. Conclusions: The authors concluded that nonsurgical periodontal therapy improved glycemic control in patients with $T_2DM$ in both groups, but no statistical difference was observed with adjunctive systemic doxycycline therapy. A further study with a larger sample size is required.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.27 no.6
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• pp.493-500
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• 2014

This paper presents findings from the assessment of the volcanic ash fragility for multi-hazard resisting vinyl greenhouse and livestock shed among the agricultural facilities. The volcanic ash fragility was evaluated by using a combination of the FOSM (first-order second-moment) method, available statistics of volcanic load, facility specifications, and building code. In this study, the evaluated volcanic ash fragilities represent the conditional probability of failure of the agricultural facilities over the full range of volcanic ash loads. For the evaluation, 6 types(ie., 2 single span, 2 tree crop, and 2 double span types) of multi-hazard resisting vinyl greenhouses and 3 types(ie., standard, coast, and mountain types) of livestock sheds are considered. All volcanic ash fragilities estimated in this study were fitted by using parameters of the GEV(generalized extreme value) distribution function, and the obtained parameters were complied into a database to be used in future. The volcanic ash fragilities obtained in this study are planning to be used to evaluate risk by volcanic ash when Mt. Baekdu erupts.

• The Journal of the Acoustical Society of Korea
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• v.42 no.4
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• pp.364-369
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• 2023

Time-delay estimation between two receivers is a technique that has been applied in a variety of fields, from underwater acoustics to room acoustics and robotics. There are two types of time delay estimation techniques: one that estimates the amount of time delay from the correlation between receivers, and the other that parametrically models the time delay between receivers and estimates the parameters by system recognition. The latter has the characteristic that only a small fraction of the system's parameters are directly related to the delay. This characteristic can be exploited to improve the accuracy of the estimation by methods such as Lasso regularization. However, in the case of Lasso regularization, the necessary information is lost. In this paper, we propose a method using Elastic Net that adds Ridge regularization to Lasso regularization to compensate for this. Comparing the proposed method with the conventional Generalized Cross Correlation (GCC) method and the method using Lasso regularization, we show that the estimation variance is very small even for white Gaussian signal sources and colored signal sources.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.25 no.7
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• pp.989-996
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• 2001

High-speed and low-speed flows are simulated numerically by flowfield-dependent mixed explicit-implicit (FDMEI) method. This algorithm depends on implicitness parameters of convection, diffusion, diffusion gradients, and source terms which are calculated from the changes of local Mach, Reynolds, Peclet, and Damkohler numbers between adjacent nodes. Convection phenomena or shock waves are resolved from Mach number-dependent implicitness parameters whereas diffusion or viscous actions are simulated by Reynolds number or Peclet number-dependent implicitness parameters. Fluctuation components of all variables are properly accommodated spatially and temporally in the FDMEI procedure. To illustrate, some benchmark example problems are presented for comparisons of the FDMEI results with other available data. These results appear to be encouraging and point toward the need for further investigations of the FDMEI theory.

• Journal of the Korean Society for Precision Engineering
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• v.32 no.2
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• pp.209-217
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• 2015

Generally welding is one of the most important processes to have a strong influence on the quality and productivity from a manufacture-based industry such as shipbuilding, automotive and machinery. The GMA(Gas Metal Arc) welding process involves large number of interdependent welding parameters which may affect product quality, productivity and cost effectiveness. To solve such problems, mathematical models are required to select the welding parameters for GMA welding process. In this study, the GMA welding process was studied using the information generated during the welding. The statistical analysis of a generalized regression approach was conducted by the following three methods: Firstly using the mathematical model (linear regression, 2nd regression); Secondly GA(Genetic Algorithm) with intelligent models; And finally using response surface analysis of models to develop the relationships between welding parameters and bead width as welding quality.