• Steel and Composite Structures
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• 제20권5호
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• pp.1043-1066
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• 2016

A new analytical solution based on a third order shear deformation theory for the problem of static analysis of cross-ply doubly-curved shells is presented. The boundary-discontinuous generalized double Fourier series method is used to solve highly coupled linear partial differential equations with the mixed type simply supported boundary conditions prescribed on the edges. The complementary boundary constraints are introduced through boundary discontinuities generated by the selected boundary conditions for the derivation of the complementary solution. The numerical accuracy of the solution is compared by studying the comparisons of deflections, stresses and moments of symmetric and anti-symmetric laminated shells with finite element results using commercially available software under uniformly distributed load. Results are in good agreement with finite element counterparts. Additional results of the symmetric and anti-symmetric laminated and sandwich shells under single point load at the center and pressure load, are presented to provide data for the unsolved boundary conditions, benchmark comparisons and verifications.

• 산업경영시스템학회지
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• 제32권1호
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• pp.34-43
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• 2009

In this thesis, we explain developing processes of the power transmission system for lift truck. Conventional power transmission system had some problems such as spatial constraints or low speed and high torque problem. Because conventional power transmission system was mainly designed for high speed vehicles. In this paper we developed power shift drive axle specialized for $2.0{\sim}3.5$ ton lift truck. Innovative structure of transmission which is built in inside axle, enables to reduce system weight and size by 40% compared to the conventional power transmission system. Also, it is possible to do additional functions such as auto parking system and anti-roll back system.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2008년도 International Symposium on Remote Sensing
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• pp.141-144
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• 2008

Many studies have been conducted on extracting buildings from ALS(Airborne Laser Scanning) data. After segmentation or classification of building points, additional steps such as generalization is required to get straight boundary lines that better approximate the real ones. In much research, orthogonal constraints are used to improve accuracies and qualities. All the lines of the building boundaries are assumed to be either parallel or perpendicular mutually. However, this assumption is not valid in many cases and more complex shapes of buildings have been increased. A new algorithm is presented that is applicable to various complex buildings. It consists of three steps of boundary tracing, grouping, and regularization. The performance of our approach was evaluated by applying the algorithm to some buildings and the results showed that our proposed method has good potential for extracting building boundaries of various shapes.

• 대한기계학회논문집A
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• 제27권4호
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• pp.559-566
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• 2003

In this study, we present a new highly accurate two-dimensional curved composite beam element. The present element, which is based on the Hellinger-Reissner variational principle and classical lamination theory, employs consistent stress parameters corresponding to cubic displacement polynomials with additional nodeless degrees to resolve the numerical difficulties due to the spurious constraints. The stress parameters are eliminated and the nodeless degrees are condensed out to obtain the (9x9) element stiffness matrix. It should be noted that the stacking sequences without transverse deformation to the load plane makes a two dimensional analysis of curved composite beams practically useful . Several numerical examples confirm the superior locking-free behavior of the present higher-order laminated curved beam element.

• 한국암반공학회:학술대회논문집
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• 한국암반공학회 2004년도 춘계학술발표회 논문집
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• pp.219-229
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• 2004

In this article a comprehensive review of the Rock Mass Rating and Q-rockmass classification systems is made with reference to their scope with in the constraints of underground mining operations. The modifications suggested by KIGAM for both the RMR and Q for the calculation of a safe unsupported span were tested for Daesung and Pyunghae underground limestone mines. Even though the suggested modifications were site specific, the additional parameters considered in the above classification systems are very significant for a design of stable underground openings, considering any general mining conditions.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 2007년도 Proceedings of ISRS 2007
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• pp.166-170
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• 2007

This paper discusses stationkeeping of COMS which accommodates two optical payloads. In order to provide good quality images to the users, the east/west stationkeeping which is strong perturbing sources shall be performed outside of mandatory observation time slots asked by users. If the east/west stationkeeping time is resulted inside of the mandatory time slots, it shall be shifted in order to be performed outside of mandatory time slot, or a new stationkeeping shall be planned. This constraint is expected to ask additional fuel consumption in comparison with tradition stationkeeping. This paper analyzes the impact of mandatory time slots to the stationkeeping fuel consumption. Orbit simulations have been conducted to determine validity of given constraints in the light of fuel requirement and stationkeeping accuracy.

• 전자공학회논문지A
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• 제32A권2호
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• pp.140-150
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• 1995

A symbolic layout generator, called Flexible Module Generator (FMG), has been developed for transgorming a given CMOS circuit netlist into an optimized symbolic layout. Contrary to other conventional module generators which place transistors either in horizontal or in vertical direction, FMG places transittors in any hence can multiples of 90$^{\circ}$. This flexible layout style can maximize the diffusion sharing and hence can reduce the wire-length for both of area minimization and performance improvement. In FMG, transistors are initially randomly placed and then selected transistors are iteratively replaced using an optimization technique based on simulated evolution. Whenever a transistor is replaced, the affected nets are rerouted. Constraints on the shape, aspect ratio, and critical path delays are considered during the optimization process. Routing is performed by using a modified maze router on polysilicon, metal 1, and metal 2 interconnection layers. additional routing grids are added, if necessary, for complete routing. Unused rows or columns are removed after routing for area minimization. Experimental reasults show that FMG synthesizes satisfactory layouts.

• 시스템엔지니어링학술지
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• 제1권1호
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• pp.67-72
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• 2005

Design and optimization study has been performed to obtain a supersonic air.launching mission for the nanosat launcher. Given mission is to launch 10kg payload to target orbit of $700km{\times}700km$. Additional design constraints are imposed by the mother plane. After the required velocity is obtained, the stag ing optimization is carried out. Serial analyses for the propulsion system and aerodynamics are performed then, the rocket trajectory optimization has been carried out. After several mission design and optimization iterations, the optimized mission which satisfies the mission target is obtained. Total weight of the three-staged air-launching rocket is 1231.4kg and the payload weight is 10 kg.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1998년도 가을 학술발표대회 논문집(III)
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• pp.712-717
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• 1998

Represtressed preflex beams do not allow tensile stress under service load by introducing additional prestressing at the lower concrete of beams. In this study, optimal design of represetressed preflex beams are numerically investigated. Design variables are dimension of plate girder. Object function is the total weight of plate girder. Constraints of the stress of plate girder and upper and lower concrete flange and lower and upper bounds on the design variables are imposed. Structural analysis is performed by D.A.R.P.(Design and Analysis of Represtressed Preflex beams). For numerical optimization, ADS(Garret N. Vanderplaats) program is used. From result of application examples, optimum designs of different cases are successfully obtained. The design program developed in this study seems efficient and robust for the optimization of represtressed preflex beams.

• Industrial Engineering and Management Systems
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• 제1권1호
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• pp.73-78
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• 2002

In this paper, we propose a constrained optimization model for conjoint analysis (a preference decomposition technique) to improve parameter estimation by restricting the relative importance of the attributes to an extent as decided by the respondents. Quite simply, respondents are asked to provide some pairwise attribute comparisons that are then incorporated as additional constraints in a linear programming model that estimates the partial preference values. This data collection method is typical in the analytic hierarchy process. Results of a simulation study show the new model can improve the predictive accuracy in partial value estimation by ordinal east squares (OLS) regression.