• Journal of Industrial Technology
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• v.39 no.1
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• pp.21-25
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• 2019

This work experimentally determined the effect of microaerobic condition on anaerobic digestion of thickened waste activated sludge in semi-continuous mesophilic digesters at hydraulic retention time of 20 days. The concentration of hydrogen sulfide was $7{\pm}2ppm$ at the microaerobic condition and $14{\pm}2ppm$ at the anaerobic condition. Removal efficiency of volatile solid was not significantly different between microaerobic ($40{\pm}8%$) and anaerobic ($38{\pm}8%$) conditions. There was no important difference between microaerobic ($1,352{\pm}98ml/d$) and anaerobic ($1,362{\pm}104ml/d$) conditions in the biogas production, either. Therefore, it could be concluded that the application of the microaerobic condition was an efficient method of the hydrogen sulfide removal from the biogas.

• Journal of the Korea Society of Computer and Information
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• v.6 no.1
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• pp.95-102
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• 2001

Supply Chain Management drawing attention of business management all over the world. This study has simulated OPT(Optimized Production Technology) to verify the Supply Chain Management's effectiveness The OPT system develops a detailed operating Philosophy, not just an operating procedure, and it includes many of the features of the JIT system and additional benefits as well The important OPT concepts such as. transfer batch. manufacturing process batch and batch it self served as a Pivotal role in increasing the productivity in manufacturing when they were altered. In this respect, this study develop the OPT simulation model, and this OPT model are evaluated by using a simulation study. It has proved that the performances of OPT model are excellent.

• Journal of the Korea Safety Management & Science
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• v.19 no.1
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• pp.203-210
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• 2017

Companies are pursuing the management of small quantity batch production or JIT(Just-in-time) system for improving the delivery response and LOB(Line Balancing) in order to satisfy consumers' increasing demands in the current global economic recession. And in order to improve the growth of production for reducing manufacturing cost, improvements of the Load Balancing have become an important reformation factor. Thus this paper is aimed at warehouse which procures materials on the assembly line in procurement logistics of automotive logistics and proceed with research on heuristic algorithm development which can increase the Load Balancing of workers. As a result of this study, when applied the primary target value, it was verified that the whole workers decreased from 28 to 24. Furthermore, when specified the secondary target value and applied algorithm once more, it was verified that the Load Balance Ratio was improved from 44.96% to 91.7%.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.40 no.1
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• pp.79-86
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• 2017

This research focused on deciding optimal manufacturing WIP (Work-In-Process) limit for a small production system. Reducing WIP leads to stable capacity, better manufacturing flow and decrease inventory. WIP is the one of the important issue, since it can affect manufacturing area, like productivity and line efficiency and bottlenecks in manufacturing process. Several approaches implemented in this research. First, two strategies applied to decide WIP limit. One is roulette wheel selection and the other one is elite strategy. Second, for each strategy, JIT (Just In Time), CONWIP (Constant WIP), Gated Max WIP System and CWIPL (Critical WIP Loops) system applied to find a best material flow mechanism. Therefore, pull control system is preferred to control production line efficiently. In the production line, the WIP limit has been decided based on mathematical models or expert's decision. However, due to the complexity of the process or increase of the variables, it is difficult to obtain optimal WIP limit. To obtain an optimal WIP limit, GA applied in each material control system. When evaluating the performance of the result, fitness function is used by reflecting WIP parameter. Elite strategy showed better performance than roulette wheel selection when evaluating fitness value. Elite strategy reach to the optimal WIP limit faster than roulette wheel selection and generation time is short. For this reason, this study proposes a fast and reliable method for determining the WIP level by applying genetic algorithm to pull system based production process. This research showed that this method could be applied to a more complex production system.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• autumn
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• pp.490-493
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• 2002

There have to be a pooled procurement in order to control construction in every stage. And we need also efficient supply chains to utilize the process. Researching and developing the method, which make it possible the supply chain management by modeling for Internet-enabled pooled procurement in construction, through breakdown in materials is currently in-progress the inside and out side of country. The objective of this paper is to find a reform while modeling the production process of cable duct moreover understanding the wasting factors in each step.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2000.04a
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• pp.135-138
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• 2000

This paper is intended to propose what manufacturing configuration (manufacturing planning and shop floor control) is suitable for the tire industry. Basically tire-manufacturing process is mixed-products, parallel-disconnected-flow-shop. Both throughput time and cycle tine are very short, the variety of tires is very high, the setup time is long, shop floor data reporting requirements is high, and there are many equipments and people working. And with no exception, tire industry also now confronts increasing requirements of delivery conformance with the above peculiar characteristics of tire manufacturing and changing market environments, this paper suggests, weekly master scheduling with no MRP is desirable and traditional kanban is right selection for shop floor control/scheduling. This paper describes why this configuration should be, using the manufacturing engineering principles and some new insights like four primitives of parallel flow shop. Generally known that shop with high parallel-product-mix and long setup time isn't good candidate for kanban. The four primitives of parallel flow shop explain why kanban is also useful scheduling technique in that environment.

• Journal of Industrial Technology
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• v.37 no.1
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• pp.32-36
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• 2017

In this study, as part of a research on the development of economical high-performance concrete with high strength and high quality, the physical properties of high-performance concrete were analyzed by substituting a certain amount of low-cost domestic silica fume exempted from the re-importation type distribution structure of the domestic production and the existing high-priced silica fume distribution structure. Performing tests to identify the physical properties of the fresh and hardened concrete and durability analogy of the concrete which use low-cost domestic silica fume and imported silica fume, the chloride ion penetration resistance test result showed that the strength difference between the low-cost silica fume and the imported silica fume is not big but the strength of the low-cost silica fume was measured higher than the imported silica fume. The chloride ion penetration resistance of all variables was measured as "very low". Since the low-cost domestic silica fume can be used as a high-performance admixture of concrete, the results suggest that it is possible to produce a more economical high-performance concrete.

• Journal of Industrial Technology
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• v.19
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• pp.301-312
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• 1999

The purpose of this paper is to study the effects of container size with multi-stage and multi-item on average inventory and customer service level in Kanban systems. We use the different distributions of demand and interarrival time for each item to show that we had better to change the container size depending on different type of item for this simulation study. The small lot size can be used for container size of a single item if there is no setup time. The container size should be identical with average order size as setup time increases. The fill rate increases if the container size is large with multi-item. However, it is difficult to establish the effective container size because the effects of the container size on the order queue time are not clear. It is suitable to use the average order size as the container size for each item if the variance of demand and interarrival time of each item is relatively small. It is effective to sue the average container size if the variance of them is relatively large.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.35 no.4
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• pp.83-97
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• 2012

In this paper, we consider a single-manufacturer single-buyer supply chain problem where a single manufacturer purchases and processes raw materials into a family of items in order to deliver a family of items to a single buyer at a fixed interval of time for effective implementation of Just-In-Time Purchasing. An integrated multi-item lot-splitting model of facilitating multiple shipments in small lots between buyer and manufacturer is developed in a JIT Purchasing environment. Previous research on the integrated model assumed that the manufacturer orders raw materials m (integer) times for every production run (lot multiplier policy for the raw material). In this paper, we consider a generalized policy in the replenishment of raw materials, allowing lot multiplier policy and lot splitting policy. An iterative solution procedure is developed to find the order interval for finished goods and raw materials, and number of shipments between buyer and manufacturer. We show by numerical example that when the integrated policy is adopted by both buyer and manufacturer in a cooperative manner, both parties can benefit.

• Proceedings of the Safety Management and Science Conference
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• 2006.11a
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• pp.373-383
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• 2006

Logistics is one of the most important factors to manage a stream of materials in economic environment. Establishing effective logistics system needs to consider some constraints which are fluctuation of materials volume, a long distance between makers and consumers, one way logistics and small quantity batch production. It is estimated that Unit Load System should be a powerful method to cope with those problems. It helps to realize the key issues which are Standardization and Logistics Pool System The Material Unification of Logistics System is able to participate in all kinds of industries including manufacturing, distribution and logistics. This system has some merits which are a long distance transportation cost down, product recovery, and treatment in the unbalance of demand and supply caused by unstable materials volume. Four strategies of Material Logistics Model are Packing Rationalization, Logistics Pool System, JIT System application and establishing effective infrastructure. The Material Unification Of Logistics System based on Unit Load System achieves efficiency of logistics and largely decreases moving cost.