• Journal of Korean Institute of Industrial Engineers
• /
• v.34 no.1
• /
• pp.1-12
• /
• 2008

The Kanban system in Just-In-Time (JIT) production is very effective in reducing the inventories when consumption rate of the final product is relatively stable. When large fluctuations exist in the consumption rate, a new production ordering policy in which the production order quantity is determined by smoothing the demands exponentially is more suitable. This new ordering policy has not been investigated sufficiently. In this research, a multi-stage production and inventory system with stock points for materials and finished items located at each stage is considered. Approximations of average inventories at each stage in the system are derived theoretically. Numerical simulations are carried out to assess the accuracy of approximations and to evaluate the effectiveness of the new ordering policy as compared with the Kanban system. As a result, it is shown that the new ordering policy can achieve significantly lower inventory costs than the original Kanban system. The new ordering policy thus emerges as a key concept for an effective supply chain management.

• Journal of Korean Institute of Industrial Engineers
• /
• v.30 no.4
• /
• pp.317-327
• /
• 2004

In mixed-model production systems, various models of products are produced alternately on the same production line. When the total number of models or the total production quantity is large, it takes a long time to determine the production sequence of the products. In this paper, we will show that in case of product rate variation problem (PRV) problem with nonidentical symmetric convex discrepancy function, an optimum sequence can be obtained by repeating an optimum sequence in a reduced subproblem.

• KSBB Journal
• /
• v.24 no.2
• /
• pp.140-148
• /
• 2009

The microbial biosurfactants can be substituted to the chemical detergents in some industrial processes. In this study we developed a biotechnological processes for the biosurfactants with microorganisms. The biosurfactants have a lot of advantages in comparision with the chemical surfactants. They are proenvironmental even during and after industrial use. But there are not so many kinds of biosurfactants. The production cost and the end price is much higher than the chemical surfactants. But nowdays there are many kinds of microorganisms, which can produce the surfactants in large quantity and fast. We tried to develop a production process for the large scale with some microorganisms. At first Candida bombicola KCTC 7145, Sphingomonas chungbukensis KCTC 2955 and Sphingomonas yanoikuyae KCTC 2818 are cultivated and studied. For the large scale production process we used molasses as a complex medium and tried to optimize the process. Molasses contains 17 to 25% of water, 45 to 50% of sugar and 25% of carbohydrate, it can be fully used as a substrate. The microorganisms have been cultivated in the diluted media with molasses 2, 5, 8 and 10%, respectively, The optimal conditions for the cultivation and the production process have been studied. For the study the optical density, glucose concentration and the surface tension were measured. Candida bombicola KCTC 7145 and the 5% molasses media was selected as an optimal condition for the production process of a biosurfactant. During cultivation of Candida bombicola KCTC 7145 in the 5% molasses medium kerosene and corn oil were added for promoting the biosurfactants.

• The Journal of Fisheries Business Administration
• /
• v.31 no.2
• /
• pp.11-26
• /
• 2000

The study tries to extend the Kang and Kim's model(1997) for evaluating fisheries damages caused by a large scale coastal reclamation. The paper tries to suggest a more generalized model by adopting new applicable variables such as the decreasing rate of production quantity amount and decreasing numbers of variables for simplification and derivation of quantative results. The paper also tries to suggest the decision model for fisheries administrative measures on the basis of the degree of damages.

• Proceedings of the Korea Concrete Institute Conference
• /
• 2003.11a
• /
• pp.273-276
• /
• 2003

The non-evaporable water and calcium hydroxides were measured by TG/DTA for studying the temperature effect on hydration of concrete mixture. The experimental parameters introduced in this study were the curing temperatures, ages and W/C ratios. The mixing temperature was also controlled to improve the efficiency of experimental work. While the mixture cured at high temperature showed the large quantity of non-evaporable water and calcium hydroxides at early age, the production rate of these hydration products was decreased as increasing the curing age, and the quantity of hydration product became smaller than that of the corresponding mixture cured at lower temperature at later age.

• Journal of applied mathematics & informatics
• /
• v.42 no.2
• /
• pp.379-390
• /
• 2024

This study proposes a fuzzy inventory model for managing large-scale production, incorporating cost considerations. The model accounts for two types of expenditure scenarios-parametric and exponential. Uncertainty surrounds holding costs, setup costs, and demand rates. The approach considers a supply chain system with a complex manufacturing process, factoring in transportation costs based on the quantity of goods and distance between the supplier and retailer. The initial crisp model is then transformed into a fuzzy simulation, incorporating specific fuzzy variables affecting inventory costs. The proposed method significantly reduces overall inventory costs for the entire supply chain. Retailer demand is linked to inventory levels, and vendor/distributor storage deteriorates over time. The fuzzy condition assumes hexagonal variables for all associated factors. The study employs the signed distance method for defuzzification to determine the optimal order quantity with hexagonal fuzzy numbers. Mathematical examples are provided to illustrate the practicality of the proposed approach.

• Asian-Australasian Journal of Animal Sciences
• /
• v.5 no.3
• /
• pp.401-409
• /
• 1992

Genotype $\times$ environment (G $\times$ E) interactions must be understood if they are to be exploited to improve animal production, particularly in production systems associated with large environmental variations. The measurement and evaluation of G $\times$ E are discussed. Examples are presented that demonstrate G $\times$ E in different breeds of beef cattle for high temperatures, internal and external parasites and changes in quantity and quality of nutrition. It is demonstrated that productivity differences between genotypes or breeds under grazing conditions arise because of differences between genotypes in the combination of production potential and resistance to environmental stresses in relation to the levels of the relevant environmental stresses that are operating at the time. The $F_1$ cross between genotypes with high production potential (e.g. European Bos Taurus breeds) and those with high resistance to environmental stress (e.g. Asian and African Bos indicus and sanga breeds) is an exceptional genotype with a unique combination of these two sets of attributes. The principles for G $\times$ E developed for beef cattle are briefly discussed in relation to dairy cattle, pigs, poultry and buffalo.

• Journal of the Korea Society for Simulation
• /
• v.28 no.2
• /
• pp.107-117
• /
• 2019

Because shipbuilding is single-product production with limited resources, production management technology is essential to manage the resources effectively and maximize the productivity of ship-process. Therefore, many shipbuilding companies are conducting research on ship production plan and process considering various constraints in the field by applying modeling and simulation. However, it is difficult to provide accurate production plan on sudden schedule and process changes, and to understand the interconnectivity between the processes that produce blocks in existing research. In addition, there are many differences between the production planning and field planning because detailed processes and quantity of blocks can not be considered. In this research, we propose the integrated process-based modeling method considering process-operation sequences, BOM(Bill of materials) and resource constraints of all the scheduled blocks in the indoor system. Through the integrated process-based model, it is easy for the user to grasp the assembly relationship, workspace and preliminary relationship of assembly process between the blocks in indoor system. Also, it is possible to obtain the overall production plan that maximizes resource efficiency without the separate simulation and resource modeling procedures because resource balancing that considers the amount of resource quantity shared in the indoor system is carried out.

• Proceedings of the Korean Institute of Building Construction Conference
• /
• 2016.05a
• /
• pp.49-50
• /
• 2016

Recently in Korea, some studies on concrete that mass quantity of additives are substituted in order to respond to the government's Low Carbon Green Growth Policy are being conducted. As on of additives, FA as an industrial by-product is used in a large quantity. However, In some of the domestic FA refineries, since some quantity of concrete without passing through the refining process is released for sales for the reasons of the shortening of production time and the cost reduction, etc., it exerts a bad influence on the quality of concrete. Therefore, in this study, there was implemented an experiment on the effects of using an extreme quality of FA which is available for distributing domestically on the engineering characteristics of lean mortar. As a result, it was found that the quality of FA exerts its effect on the compression strength bigger than the flow property or the air volume.

• Journal of Energy Engineering
• /
• v.13 no.1
• /
• pp.1-11
• /
• 2004

Gasification is the essential technology that can meet the interim hydrogen demand of large quantity before entering the hydrogen economy. Although the hydrogen production that is based upon the pure renewable energy like wind and solar power will eventually prevail, the interim mass production of hydrogen for the next ten to twenty years will come from the technologies that can demonstrate the economic feasibility in production cost with a high potential in minimizing CO$_2$ generation and in improving plant efficiency. Particularly, feedstock such as natural gas, coal, petroleum residual oil, wastes, and biomass appears to be utilized in Korea as hydrogen source, at least during the short and medium period of time, owing to the advantage in production cost. Because one of the main reasons behind the recent hydrogen issue is the reduction requirement of CO$_2$ that would be controlled according to the climate change protocol, hydrogen production technologies must be developed to yield the minimal CO$_2$ generation.