• Journal of the Korean Society for Precision Engineering
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• v.19 no.4
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• pp.109-116
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• 2002

The solution of the aircraft wing spar cross-section area optimization problem is obtained by the response surface method. The object function of the problem is wing total weight, design variables are spar cross-section areas, constraints are the conditions that the stresses at the each spar is less than the allowable stress. D-Optimal condition is utilized to obtain the experimental points to construct the response surfaces. D-Optimal experimental points are obtained by the commercial software "Deign-Expert". Response values for the object function and constraints for each experimental point are calculated by the NASTRAN. Response surfaces for object function and constraints are approximated from the response values by the least square method. The optimization solution is obtained by the DOT for the response surfaces of object function and constraints. The optimization results obtained from the response surface are compared with the results obtained by the NASTRAN SOL200.

• Journal of the Korean Data and Information Science Society
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• v.9 no.2
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• pp.255-262
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• 1998

In this paper, we study the saddlepoint approximations for the ratio of independent random variables. In Section 2, we derive the saddlepoint approximation to the probability density function. In Section 3, we represent a numerical example which shows that the errors are small even for small sample size.

• Journal of Aerospace System Engineering
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• v.12 no.6
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• pp.41-49
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• 2018

In this study, the theoretical dynamic characteristics of a thin-walled composite beam with a single-cell of chordwise asymmetric cross-section was studied. Mathematical modeling was done by considering the transverse shear effects, the warping restraint effects, the constant taper ratio in the longitudinal direction of the beam, and the geometrical cross-section ratio. The mass coefficients, stiffness coefficients, and Eigen frequencies of the selected section were investigated. In particular, the effects of the taper ratio and cross-section ratio of the model on the Eigen frequencies were analyzed and compared when the asymmetry of the section was considered and the warping function was not corrected.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1057-1062
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• 2008

Representing a complex, three-dimensional shape, such as an automobile, requires a large amount of CAD data consisting of millions of approximated discontinuous points, which makes it difficult or even impossible to efficiently optimize the entire shape. For this reason, in this paper, function based design method is proposed to optimize the external shape of an automobile. A vehicle modeling function was defined in the form of a Bernstein polynomial to smoothly express the complex 2D and 3D automobile configurations. The sub-sectional parts of the vehicle modeling function are defined as section functions through classifying each subsection of a box model. It is shown that the use of the vehicle modeling functions has the useful advantages in an aerodynamic shape optimization.

• Journal of Veterinary Clinics
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• v.24 no.4
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• pp.522-528
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• 2007

A 3-year-old male Maltese dog(weighing 2.5 kg) was referred with an excessive movement of mandible and depression. Comprehensive diagnostic investigation revealed an end-stage of renal disease with secondary hyperparathyroidism. The renal allograft was performed after the condition of dog was stabilized by hemodialysis and medical treatment. After transplantation, the renal function of this dog was returned to normal. thereafter, the dog died suddenly without apparent clinical signs. The subsequent pathological studies revealed the actual etiology of death was not clearly identified However acute pancreatitis caused by abrupt introduction of food after prolonged luting might be involved in the etiology. This case study showed the necessity of pancreatic function test in postoperative management after renal transplantation.

• Journal of the Society of Naval Architects of Korea
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• v.53 no.3
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• pp.188-194
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• 2016

Accurate estimation of shear flows in thin-walled beam section is the key issue to evaluate shear stress distribution of ship hull transverse section under the shear forces acting on hull girder. It is regarded that the method using the warping functions obtained by finite element formulation is the state of the art of this field. Recently, however, IACS took effect the new version of CSR in which direct calculation process of shear flow was suggested. In the direct calculation process, shear flow of ship hull section can be obtained by the addition of determinate and indeterminate shear flows calculated respectively. So, in this paper, the shear flow evaluation codes based on the process proposed by IACS CSR and warping function based method were developed respectively. The calculated results of shear flows for the several examples of ship sections were compared with each other and considered in detail.

• Korean Journal of Optics and Photonics
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• v.15 no.3
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• pp.200-213
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• 2004

The realization of partially coherent Gaussian Schell-model beams with isotropic cross section and anisotropic degree of coherence function is investigated theoretically. An optical system is devised to transform diffused light generated by passing the Gaussian beam of the He-Ne laser thorough a rotating holographic diffuser to the partially coherent Gaussian Schell-model beam with isotropic cross section and anisotropic degree of coherence function. Analytic design equations are formulated and design examples are presented.

• Bulletin of the Korean Mathematical Society
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• v.25 no.2
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• pp.243-246
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• 1988

Let M(z)=exp (-1+z/1-z) be the unit singular inner function. See [1] or [2] for the basic facts about inner functions. We define the iterations of M9z) as (Fig.) Since the composition M$_{2}$(z)=M.M(z) is known (see [5] for example) to be singular inner function it has the "cannonical" representation (Fig.) where .mu. is a finite, positive singular Borel measure on the unit circle T. In section 2, we have explicit cannonical representation of M$_{2}$(z) by determining the singular measure .mu. In section 3 we show that (Fig.) These facts might have been known but could not be found in the literature.iterature.

• Journal of the Korean Institute of Navigation
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• v.17 no.1
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• pp.91-98
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• 1993

This paper presents a class of Bayes estimation of component steady-state availability . Throughout this paper, we will denote the mean time between failure and the mean time between repair by MTBF and MTBR respectively. In section 2 , we investigated Bayes estimation of the steady-state availability for noninformative prior density function and in section 3, we compute Bayes estimation for conjugate prior density function.

• Magazine of the Korean Society of Agricultural Engineers
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• v.36 no.2
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• pp.111-122
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• 1994

In this study, an algorithm which can be applied to the optimum design of simple steel plate girders was developed, and efficient optimization strategies for the solution of algorithm were found out. The optimum design algorithm consists of 3-levels of optimization. In the first and second levels of optimization, the absolute maximum bending moment and shearing force are extracted and in the third level of optimization, the optimum cross section of steel plate girder is determined. For the optimum design of cross section, the objective function is formulated as the total area of cross section and constraints are derived in consideration of the various stresses and the minimum dimension of flange and web based on the part of steel bridge in the Korea standard code of road bridge. Sequential unconstrained minimization technique using the exterior penalty function method(SUMT-EP), sequential linear programming(SLP) and sequential quadratic programming (SQP) are proved to be efficient and robust strategies for the optimum design of simple plate girder cross section. From the reliable point of view, SLP is the most efficient and robust strategy and SQP is the most efficient one from the viewpoint of converguency and computing time.