• Journal of the Korea Society for Simulation
• /
• v.20 no.2
• /
• pp.67-76
• /
• 2011

Order picking in automotive service parts warehouses is considered to be the most labor-intensive operation. Such warehouses contain hundreds of thousands of items, but normally 20% of products contribute to about 80% of turnover according to Pareto's 80-20 principle. Therefore most fast moving items are located near an outbound area which is called the "Golden Zone". Order picking routing efficiency is related to productivity and labor cost. However, most companies use simple methods. In this paper, we describe a series of computational experiments over a set of test cases where, we compared various previously existing routing heuristics to an optimal algorithm. We focus on examining the influence of the golden zone on the performance and selection of routing methods. The results obtained show that the optimal routing method increases the productivity at least 17.2%, and all the routing methods have better performance as the pick up rate from the golden zone increases.

• Journal of the Korea Concrete Institute
• /
• v.20 no.6
• /
• pp.705-712
• /
• 2008

This study carried out simulation for structural layout design for concrete structures by using the models of the ground structure method. The micro lattice truss is modeled as assemblage of a number of unit cells. The progress of analysis repeat to undergo finite element analysis to feed-back results of stress to the stiffness of each member. Through the repeated this analysis, truss model is represented to form the topological materials and the structural shape with the use of the local stress condition without mathematical optimum tools. It is successful to analyse the shape-layout problem as numerical samples on the lattice truss model.

• Proceedings of the Korean Nuclear Society Conference
• /
• 1999.05a
• /
• pp.25-25
• /
• 1999

• Proceedings of the Korean Nuclear Society Conference
• /
• 1999.10a
• /
• pp.365.1-365
• /
• 1999

• Journal of Advanced Marine Engineering and Technology
• /
• v.39 no.1
• /
• pp.8-12
• /
• 2015

Non-esterified bio-diesel fuel saves cost by no esterified process and its performance was more similar to diesel oil than esterified bio-diesel fuel when the fuel blended 95% diesel oil and 5% it was used on diesel engine with electronic control system. A performance optimization is necessary for application of non-esterified bio-diesel fuel blended with diesel oil 95% on the latest diesel engine. In this study, test using fractional factorial design was accomplished at 25% and 50% partial load in order to evaluate influence of controllable 6 factors on responses such as specific fuel consumption, nitrogen oxides and coefficiency of variation of indicated mean effective pressure as basic experiment for performance optimization of this fuel. It is cleared that the injection timing and common rail pressure of 6 factors are mainly effective and its effect level is different according to load.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.5
• /
• pp.294-302
• /
• 2020

In a genetic algorithm, computer simulations are performed based on the natural evolution process of life, such as selection, crossover, and mutation. The genetic algorithm searches the approximate optimal solution by the parallel arrangement of Schema, which has a short definition length, low order, and high adaptability. This study examined the possibility of improving the efficiency of the optimal solution by considering the characteristics of the building block hypothesis, which are one of the key operating principles of a genetic algorithm. This study evaluated the efficiency of the optimization results according to the gene sequence for the implementation in solving problems. The optimal design problem of the water pipe was selected, and the genetic arrangement order reflected the engineering specificity by dividing into the existing, the network topology-based, and the flowrate-based arrangement. The optimization results with a flowrate-based arrangement were, on average, approximately 2-3% better than the other batches. This means that to increase the efficiency of the actual engineering optimization problem, a methodology that utilizes clear prior knowledge (such as hydraulic properties) to prevent such excellent solution characteristics from disappearing is essential. The proposed method will be considered as a tool to improve the efficiency of large-scale water supply network optimization in the future.

• Aerospace Engineering and Technology
• /
• v.4 no.1
• /
• pp.66-76
• /
• 2005

In this study, star visibility analysis of a star tracker is performed by using a statistical apprach. The probability of the Sun and the Earth proximity, the solar array masking probability, and the solar array blinding probability by the Sun light are obtained from the arbitrary chosen satellite positions as a function of a line of sight vector of the star tracker in several satellite attitude modes. This analysis demonstrates that the optimized star tracker accomodations can be determined to be an elevation angle -40o and two azimuth angles $-35^{circ}$ and $-150^{circ}$.

• The Journal of the Acoustical Society of Korea
• /
• v.23 no.1
• /
• pp.40-46
• /
• 2004

The equivalent source method (ESM) uses two groups of equivalent source positions. One group includes the first order images of the sound source inside the enclosure. The positions of the other group are usually on a spherical surface some distance outside the enclosure. A proper selection of the positions for the far field sources could greatly improve the performance of the modeling accuracy and reduce the number of the sources to achieve the required accuracy. This study uses optimally distributed far field source positions on the surface of enlarged version of the rectangular enclosure instead of using typical spherical distribution. Simulations using various sizes of the box shaped distribution are executed and optimal positions are searched using an optimization technique from the larger number of candidate positions. The results of using these far field source positions are compared and analyzed.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.24 no.2
• /
• pp.102-107
• /
• 2014

The engine excitation forces are considered as major vibration source for the forklift truck, especially in small class. Even though the current engine mounting system designs are acceptable for vibration isolation, the performance of the engine mounting system is still required for the tendency of light weight, higher power and driver's higher vibration requirement. In this paper vibration reduction technique of forklift engine which is supported on rubber mounts is presented. Based on the dynamic model of resilient engine mounting system, design evaluation program is established. The design optimization technique and evaluation method of system properties are discussed. Effects of optimal design are validated through comparison with test results.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.9 no.1 s.24
• /
• pp.72-79
• /
• 2006

This study was focused on analyzing mathematical model for optimal allocation of surveillance equipment which is operated on the natural geographical condition, such as DMZ fence area. Optimal allocation algorithm was studied for the equipment to develop the whole surveillance and watch model for the two area as testing. Also 3D visualization program was developed to display and analyze the detecting effect. The results show that our suggested model will be available for enhancing security condition on the watching area.