• Journal of Korean Society of Industrial and Systems Engineering
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• v.31 no.3
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• pp.17-23
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• 2008

In this research article, scheduling a casting sequence in a job-shop type foundry involving a variety of casts made of an identical alloy but with different shapes and II weights, has been investigated. The objective is to produce the assigned mixed orders satisfying due dates and obtaining the highest ingot efficiency simultaneously. Implementing simple integer programming instead of complicated genetic algorithms accompanying rigorous calculations proves that it can provide a feasible solution with a high accuracy for a complex, multi-variable and multi-constraint optimization problem. Enhancing the ingot efficiency under the constraint of discrete ingot sizes is accomplished by using a simple and intelligible algorithm in a standard integer programming. Employing this simple methodology, a job-shop type foundry is able to maximize the furnace utilization and minimize ingot waste.

• Journal of the Korean housing association
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• v.11 no.4
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• pp.1-8
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• 2000

Our country, korea, has become the aged society in 2000. Thus, the problem of the old assumes an aspect of wide scope and variety, and it becomes a social problem. the world does its utmost to settle the welfare of the old, and international action plan and UN principle for the old have been established in recent years. keeping pace with this trend, our country carries forward a middle and long term plan of welfare of the old. However, facilities for the old in apartment complexes are established not in a level of the welfare of the old, but in a level of relief work or the protection of the old. Therefore this study suggests a series of reform measures of the facilities for the old and the direction of the plan of welfare facilities for the old, by studying the present situation and actual conditions of facilities in apartment complexes.

• ETRI Journal
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• v.28 no.6
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• pp.799-802
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• 2006

Capacity has always been a major concern in wireless networks. This letter studies the impact of mobility on the overall system capacity in wireless cellular networks. In this letter, we present a simple system model which we developed to capture the inherent relationships among system capacity, new call blocking probability, handoff dropping probability, call terminating probability, and bandwidth utilization rate. We investigate the complex relationship between mobility and capacity-related parameters. Through simulation, we demonstrate that mobility has a significant impact on capacity and is reversely proportional to the bandwidth reserved for handoff traffic.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1994.04a
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• pp.357-363
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• 1994

In many industrial situations the human acts as the primary scheduler since there often exist various constraints and considerations that may not be mathematically or quantitatively defined. For proper design of interactive scheduling systems, how human strategy and performance are affected by the fashion of human-computer interaction at various levels of task complexity should be investigated. In this study, two scheduling experiments were conducted. The first one showed that human schedulers could perform better than simple heuristic rules with each of typical performance measures such as average machine utilization, average tardiness, and maximum tardiness. In experiment 2, the effect of providing computer-generated initial solution was investigated. The results was that in complex problems the subjects performed significantly better when the initial solutions were generated by themselves, evidencing the importance of the continuity of strategic search through the problem.

• International Journal of CAD/CAM
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• v.6 no.1
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• pp.19-27
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• 2006

To survive in the current shipbuilding industry it is of vital importance for shipyards to achieve an optimal utilization of resources, make an achievable planning and ensure that this planning is kept. Possible problems should be eliminated before production starts and if unexpected disturbances occur in the actual production the right measures should be taken. Due to the dynamic nature of the production process, the continuous variation in products and the complexity of both, all this can hardly be achieved with conventional static planning and analysis systems. Simulation provides a solution here, since this enables the modelling and evaluation of the dynamic relations between product and production process. After a global introduction to production simulation in general and the application of simulation at the Flensburger shipyard, this paper presents a tool that has been developed to simulate the various complex assembly processes taking place at shipyards. Subsequently the simulation model for the subassembly production at Flensburger, in which this tool is applied, will be discussed.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.19 no.37
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• pp.201-210
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• 1996

Although FMS implementation in Korea is not yet mature, the worldwide empirical data shows the diffusion of FMS is inevitable in near future. As the reletionships between the high capital cost and the relative benefits and advantages are complex to analyse, it is rather beneficial to prepare the effective operation strategies which exploit the FMS flexibility, such as machine loading with alternative routing and dispatching rules. This paper shows the formulation applying a goal programming model for the loading problem with objectives of minimizing the production cost and maximizing the machine utilization, including constraints such as machine tool capacity and demands, etc. A realistic random FMS model is developed for illustration. Since loading and dispatching are a composite of two interdependent tasks, simulation is made to investigate the interactions between the two.

• Asian-Australasian Journal of Animal Sciences
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• v.22 no.7
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• pp.915-922
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• 2009

Ruminants possess the capacity to digest very large amounts of starch. However, in many cases diets approach 60% starch and even small inefficiencies present opportunities for energetic losses. Ruminal starch digestion is typically 75-80% of starch intake. On average, 35-60% of starch entering the small intestine is degraded. Of the fraction that escapes small-intestinal digestion, 35-50% is degraded in the large intestine. The low digestibility in the large intestine and the inability to reclaim microbial cells imposes a large toll on post-ruminal digestive efficiency. Therefore, digestibility in the small intestine must be optimized. The process of starch assimilation in the ruminant is complex and remains an avenue by which increases in production efficiency can be gained. A more thorough description of these processes is needed before we can accurately predict digestion occurring in the small intestine and formulate diets to optimize site of starch digestion.

• Journal of the Korean School Mathematics Society
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• v.2 no.1
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• pp.93-104
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• 1999

The subject of this study was the graph of relation of direct inverse proportion, linear function and quadratic function in the 1st, 2nd and 3rd grade of current middle school mathematics curriculum. GSP materials were developed to simplify the principle, trait and characteristics of graphs and make them easier to understand. The overall aim of the materials is to improve the effectiveness of teaching and learning through the utilization of enhanced students' practice. Additionally, the use of the GSP will be useful in the development of mere effective materials. The effectiveness of the GSP materials will be as followings. 1. The step by step approach of GSP materials through computer interaction will enhance students motivation and interest in mathematics. 2. By presenting the subject matter simply and in a variety of ways, difficult concepts can be understood without the use of complex mathematical calculation. 3. The GSP program is different from CAI and other software programs. It should be used only after learning how to input and output data.

• Solar Energy
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• v.18 no.3
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• pp.169-175
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• 1998

Metal hydrides can be used for the purpose of heat storage and transportation from the industrial complex which own recoverable waste heats to the neighboring cities by the medium of hydrogen. The properties of metal hydrides, some problems of heat transportation using metal hydrides, and the example of heat transportation system were discussed.

• Journal of the Optical Society of Korea
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• v.16 no.2
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• pp.170-173
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• 2012

We present a method that enables dual threshold voltages in a vertical alignment liquid crystal device, through which the gamma shift can be reduced with no subsequent decrease in the contrast ratio. By forming polymer layers, the threshold voltage shift is accomplished through the utilization of the voltage drop effect. We expect that the proposed method can be applied to the conventional 4-domain mode in order to achieve an 8-domain mode without the need for complex driving schemes.