• Journal of Navigation and Port Research
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• v.28 no.6
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• pp.531-539
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• 2004

In this paper, we propose a new heuristic solution for 3D container packing problem for the variable sizes and types of freight. Frist of all, we consider the total cost of container charge i.e., handling, loading and transportation, where each freight will be specifically identified The types of containers and its number to be loaded am be selected automatically by minimizing the total cost of container charge. Maximization of loading space am be achieved efficiently by operating the palletizing and/or depalletizing of freight. By considering these factors we can determine the position of freight in the container and the loading sequence to be packing into the container. In container packing simulation, we can verify that the proposed heuristic algorithm indicates more efficiency space utilization and shows the possibility of using on commercial business.

• Computers and Concrete
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• v.3 no.5
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• pp.301-312
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• 2006

Experimental research revealed that the spatial dispersion of aggregate grains exerts pronounced influences on the mechanical and durability properties of concrete. Therefore, insight into this phenomenon is of paramount importance. Experimental approaches do not provide direct access to three-dimensional spacing information in concrete, however. Contrarily, simulation approaches are mostly deficient in generating packing systems of aggregate grains with sufficient density. This paper therefore employs a dynamic simulation system (with the acronym SPACE), allowing the generation of dense random packing of grains, representative for concrete aggregates. This paper studies by means of SPACE packing structures of aggregates with a Fuller type of size distribution, generally accepted as a suitable approximation for actual aggregate systems. Mean free spacing $\bar{\lambda}$, mean nearest neighbour distance (NND) between grain centres $\bar{\Delta}_3$, and the probability density function of ${\Delta}_3$ are used to characterize the spatial dispersion of aggregate grains in model concretes. Influences on these spacing parameters are studied of volume fraction and the size range of aggregate grains. The values of these descriptors are estimated by means of stereological tools, whereupon the calculation results are compared with measurements. The simulation results indicate that the size range of aggregate grains has a more pronounced influence on the spacing parameters than exerted by the volume fraction of aggregate. At relatively high volume density of aggregates, as met in the present cases, theoretical and experimental values are found quite similar. The mean free spacing is known to be independent of the actual dispersion characteristics (Underwood 1968); it is a structural parameter governed by material composition. Moreover, scatter of the mean free spacing among the serial sections of the model concrete in the simulation study is relatively small, demonstrating the sample size to be representative for composition homogeneity of aggregate grains. The distribution of ${\Delta}_3$ observed in this study is markedly skew, indicating a concentration of relatively small values of ${\Delta}_3$. The estimate of the size of the representative volume element (RVE) for configuration homogeneity based on NND exceeds by one order of magnitude the estimate for structure-insensitive properties. This is in accordance with predictions of Brown (1965) for composition and configuration homogeneity (corresponding to structure-insensitive and structure-sensitive properties) of conglomerates.

• Journal of the Korean Society for Precision Engineering
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• v.28 no.3
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• pp.370-376
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• 2011

Recently, the application range of plastic gears is widely expanding by the development of engineering plastics with good mechanical properties. Plastic gears have excellent performances such as light weight, water resistance and vibration absorbing ability for metallic gears. In this study, the optimization of injection molding process was done for the large disk type plastic gears of auto phoropter. Design Of Experiment (Taguchi method) was adopted to find a tendency of molding conditions that influence the flatness of disk type gear. Four main factors for molding conditions were selected based on injection temperature, filling time, packing pressure and mold temperature. Also, Filling, packing and cooling analyses were carried out to evaluate Z directional deflection of large disk type gear by using the simulation software (Moldflow) based on the DOE. From the results, it was found that the injection temperature and packing pressure are the most sensitive parameters for the Z directional deflection of large disk type gears.

• Journal of the Korea Society for Simulation
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• v.10 no.1
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• pp.1-12
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• 2001

This article describes the application of discrete event simulation in a process industry (coffee manufacturing) as a daily production-scheduling tool. A large number of end products (around 300), sporadic demand, and limited shelf life of coffee (90 days) make it difficult to generate feasible production schedules manually. To solve this problem, an integrated system was developed incorporating discrete event simulation methodology into scheduling process. The integrated system is comprised of two components: a scheduling program and a simulation model. The scheduling program is used to generate daily schedules for roasting, grinding, and packing coffee. The simulation model uses the generated schedules to simulate the production of coffee and regenerates a modified production schedule. In this paper, each of the components will be described in detail, evaluated in terms of performance factors, and validated with a set of real production data. Although this article focuses on a specific system, we will share our experiences and Intuitions gained and encourage other process industries to develop simulation-based scheduling tools.

• Fire Science and Engineering
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• v.30 no.4
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• pp.46-58
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• 2016

In this study, the stress applied to screw section, strain, displacement, von Mises stress, and the compression stress applied to the rubber packing for watertightness are estimated with computer simulation when the tightening torque of valve socket is in the range of $10{\sim}130N{\cdot}m$ in order to analyze the influence of valve socket screw section in accordance with the excessive tightening which is supposed to be the cause of water leakage from the synthetic resin piping for fire fighting application of sprinkler equipment, and for the sake of verifying this, adequate value of tightening torque and the value of the compression stress of rubber packing are investigated by examining the number of connected thread for each tightening torque, the deformation state of valve socket and rubber packing and conducting the water hammering test. The result of this test is expected to be utilized as the data required for revising the standard or technical criteria to prevent the water leakage of the synthetic resin piping for fire fighting application.

• The Transactions of the Korea Information Processing Society
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• v.5 no.4
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• pp.883-891
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• 1998

This paper proposes a scheme to exploit SIMD parallelism in the simulation of Cellular Automata models. The basic idea is to increase the utilization of an ALU in the underlying computer and to reduce simulation time by exploiting the parallelism. Thus, several cells are packed into a computer word and transit their state together. To show the performance of the proposed simulation scheme, two Cellular Automata models are simulated under three distinct hardware environments. The results show considerably high simulation speed-up for every case. Especially, the simulation speedup with the proposed simulation scheme reaches nearly 20 times in the best case.

• Proceedings of the Korea Society for Simulation Conference
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• 2000.11a
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• pp.28-33
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• 2000

This article describes the application of discrete event simulation in a process industry (coffee manufacturing) as a daily production-scheduling tool. A large number of end products (around 300), sporadic demand, and limited shelf life of coffee (90 days) make it difficult to generate feasible production schedules manually. To solve this problem an integrated system was developed incorporating discrete event simulation methodology into scheduling process. The integrated system is comprised of two components: a scheduling program and a simulation model. The scheduling program is used to generate daily schedules for roasting, grinding, and packing coffee. The simulation model uses the generated schedules to simulate the production of coffee and regenerates a modified production schedule. In this paper, each of the components will be described in detail, evaluated in terms of performance factors, and validated with a set of real production data. Although this article focuses on a specific system, we will share our experiences and intuitions gained and encourage other process industries to develop simulation-based scheduling tools.

• Journal of Advanced Navigation Technology
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• v.25 no.3
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• pp.211-216
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• 2021

Multiple UAV System has been used for various purposes such as reconnaissance, networking and aerial photography. In such systems, it is essential to form and maintain the formation of multiple UAVs. This paper proposes the algorithm that produces an autonomous distributed control for each vehicle for a flexible formation. This command is a repulsive force in the form of the second-order system by the nearest UAV or mission area. The algorithm uses the relative position/speed through sensing and communication for calculating the command without external intervention. The command allows each UAV to follow the reference distance and fill the mission area as densely as possible without overlapping. We determine the reference distance via optimization technique solving the packing problem. The mission area comprises the desired formation outline and can be set flexibly depending on the mission. Numerical simulation is carried out to verify the performance of the proposed algorithm under a complex and flexible environment. The formation is formed in 26.94 seconds and has a packing density of 71.91%.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.3
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• pp.819-837
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• 2014

Data centers, which implement cloud service, have been faced up with quick growth of energy consumption and low efficiency of energy. 60GHz wireless communication technology, as a new option to data centers, can provide feasible approach to alleviate the problems. Aiming at energy optimization in 60GHz wireless data centers (WDCs), we investigate virtualization technology to assign virtual resources to minimum number of servers, and turn off other servers or adjust them to the state of low power. By comprehensive analysis of wireless data centers, we model virtual network and physical network in WDCs firstly, and propose Virtual Resource Mapping Packing Algorithm (VRMPA) to solve energy management problems. According to VRMPA, we adopt packing algorithm and sort physical resource only once, which improves efficiency of virtual resource allocation. Simulation results show that, under the condition of guaranteeing network load, VPMPA algorithm can achieve better virtual request acceptance rate and higher utilization rate of energy consumption.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.15 no.1
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• pp.108-112
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• 2006

A Study of birefringence in an aspheric lens of injection molding became more important to improve its optical properties. In the present study, the experimental study was carried out to investigate the relationship between birefringence and injection molded conditions. The processing factors are conditions include packing pressure, packing time, injection speed, melt temperature of optical resin and wall temperature. Birefringence was observed figures by using a polarizer in light. This experiments were carried out using the simulation software and injection molding machine.