• Journal of Microbiology and Biotechnology
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• v.23 no.8
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• pp.1084-1091
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• 2013

In this paper, two statistical methods were applied to optimize medium components to improve the production of the milk-clotting enzyme by Bacillus amyloliquefaciens D4. First, wheat bran juice, skim milk powder, and $Na_2HPO_4$ were shown to have significant effects on D4 enzyme production using the Plackett-Burman experimental design. Subsequently, an optimal medium was obtained using the Box-Behnken method, which consisted of 3.31 g/l of skim milk powder, 5.0 g/l of sucrose, 0.1 g/l of $FeSO_4{\cdot}7H_2O$, 0.1 g/l of $MgSO_4{\cdot}7H_2O$, 0.1 g/l of $MnSO_4{\cdot}2H_2O$, 0.1 g/l of $ZnSO_4{\cdot}7H_2O$, 1.52 g/l of $Na_2HPO_4$, and 172.45 g/l of wheat bran juice. With this optimal medium, the milk-clotting enzyme production was remarkably enhanced. The milk-clotting enzyme activity reached 3,326.7 SU/ml after incubation of 48 h, which was 1.76-fold higher than that of the basic medium, showing that the Plackett-Burman design and Box-Behnken response surface method are effective to optimize medium components, and B. amyloliquefaciens D4 possessed a high rennet-producing capacity in the optimal medium.

• Archives of design research
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• v.18 no.1 s.59
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• pp.205-214
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• 2005

A development proposal that maximizes the trend of travel souvenir and articles toward tourism and natural resources through utilization of the Limited Production method was the focus of the present research. First, the flaws of travel souvenir and articles, currently produced in Inje, Kangwon-Do, were identified, as were the regional uniqueness of the area. The comparative advantages of developmental conditions of the above-specified region to various other Si/Kun regions were demonstrated to ascertain the optimal production method of travel souvenir and articles. The results are as follows. Superior supply of,7aw materials necessary for production of wood-worked travel souvenir and articles are abundantly available and the dose proximity of 17 existing workshops self-contain the production capacity to sustain the Limited Production method. Furthermore, the regional governing council conveyed positive attitudes towards the prospect of creating a regional production complex of wood-worked travel souvenir and articles. The results demonstrate that the optimal method of maximizing the trend of travel souvenir and articles toward tourism and natural resources is achieved through systematic collaboration of industry, education, and tourism that promote development, production, and merchandising of Inje's regional travel souvenir and articles.

• Journal of Korean Institute of Industrial Engineers
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• v.33 no.2
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• pp.246-253
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• 2007

All of the machines in a production line can be classified into bottleneck and non-bottleneck machines. A bottleneck is a resource whose capacity limits the throughput of the whole production facility. This paper addresses a batch sizing problem at the bottleneck machine. Traditionally, most batch sizing decisions have been made based on the EOQ (economic order quantity) model where setup and inventory costs are considered while throughput rate is assumed to be given. However, since batch size affects the capacity of the bottleneck machine, the throughput rate may not be constant. As the batch size increases, the frequency of the setup decreases. The saved setup time can be transferred to processing time, which results in higher throughput. But, the larger batch size may also result in longer lead time and larger WIP inventory level. This paper presents an alternative method to determine batch size at the bottleneck machine in a manufacturing line. A linear search algorithm is introduced to find optimal throughput rate and batch size at the same time. Numerical examples are provided to see how the proposed method works and to investigate the effects of some parameters.

• Management Science and Financial Engineering
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• v.12 no.1
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• pp.95-112
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• 2006

Disassembly scheduling is the problem of determining the quantity and timing of disassembling used or end-of-life products while satisfying the demand of their parts and/or components over a planning horizon. The case of assembly product structure is considered while the resource capacity constraints are explicitly considered. A cost-based objective is considered that minimizes the sum of disassembly operation and inventory holding costs. The problem is formulated as an integer programming model, and a two-stage heuristic with construction and improvement algorithms is suggested in this paper. To test the performance of the heuristic, computational experiments are done on randomly generated problems, and the results show that the heuristic gives near optimal solutions within a very short amount of computation time.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.60 no.8
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• pp.1467-1472
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• 2011

This paper presents an optimal operation of microgrid systems and considering a tie-lines capacities that concerned each grid. The microgrid system consists of a wind turbine, a diesel generator, and a fuel cell. An one day load profile and wind resource for wind turbine generator were used for the study. For the grid interconnection, tie-line capacities were applied as constraints. The capacity constraints of tie-lines in production cost analysis are very important issues in the operation and planning of microgrid. In optimization, the Harmony Search (HS) algorithm is used for solving the problem of microgrid system operation which a various generation resources are available to meet the customer load demand with minimum operating cost. The application of HS algorithm to optimal operation of microgrid proves its effectiveness to determine optimally the generating resources without any differences of load mismatch.

• Ocean and Polar Research
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• v.40 no.4
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• pp.237-247
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• 2018

This study aims to estimate optimal harvests, fishing efforts, and stock levels of hairtail harvested by the large pair bottom trawl, the large otter trawl, the large purse seine, the offshore long line, and the offshore angling fisheries by using the surplus production models and the current value Hamiltonian method. Processes of this study are as follows. First of all, this study estimates the standardized fishing efforts regarding the harvesting of the hairtail by the above five fishing gears based on the general linear model developed by Gavaris. Secondly, this study estimates environmental carrying capacity (k), intrinsic growth rate (r), and catchability coefficient (q) by applying the Clarke Yoshimoto Pooley (CY&P) model among various surplus production models. Thirdly, this study estimates the optimal harvests, fishing efforts, and stock levels regarding the hairtail by the current value Hamiltonian method, including the average landing price, the average unit cost, and the social discount rate. Finally, this study attempts a sensitivity analysis to figure out changes in optimal harvests, fishing efforts, and stock levels due to changes in the average landing price and the average unit cost. As results induced by the current value Hamiltonian method, the optimal harvests, fishing efforts, and stock levels regarding the hairtail caught by several fishing gears were estimated as 33,133 tons, 901,080 horse power, and 79,877 tons, respectively. In addition, from the results of the sensitivity analysis, first of all, if the average landing price of the hairtail constantly increases, the optimal harvests of it increase at a decreasing rate, and then harvests finally slightly decrease as a result of decreases in stock levels. Secondly, if the average unit cost of fishing efforts continuously increases, the optimal fishing efforts decreases, but optimal stock levels increase. Optimal harvests start climbing and then decrease continuously due to increases in the average unit cost. In summary, this study suggests that the optimal harvests (33,133 tons) were larger than actual harvests (25,133 tons), but the optimal fishing efforts (901,080 horse power) were much less than estimated standardized fishing efforts (1,277,284 horse power), corresponding to the average of the recent three years (2014-2016). This result implies that the hairtail has been inefficiently harvested and recently overfished due to excessive fishing efforts. Efficient management and conservation policies on stock levels need to be urgently implemented. Some appropriate strategies would be to include the hairtail in the Korean TAC species or to extend the closed fishing season for this species.

• Journal of Korean Institute of Industrial Engineers
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• v.4 no.2
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• pp.91-96
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• 1978

A modeling framework and its computational methodology for an industrial sector of the economy are investigated. The suggested industrial sector model is characterized by a programming (process analysis) representation of a production sector and an econometric estimation of the price sensitive (own and cross-prices) demands. By introducing the price sensitive demands into the process analysis representation of the production sector, it becomes possible to analyze and plan the pricing policy, the optimal production schedules and capacity expansion plans within a single framework. The computational scheme suggested in the report is based on the iterative approach each of which solves a separable convex programming problem.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.10 no.16
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• pp.89-100
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• 1987

In this paper, we present the effect of buffer storage capacity un two-stage transfer lines in such a way as to introduce the production rate to be reduced which is called a Slowed Down(SD) state. A Markov model is used to establish a formulation for the analysis of the delays associated with the stage to be starved or blocked. Operating policies are proposed by analyzing the effect of the decision variables such as the production rates, the failure rates, buffer capacities and SD rates through computer simulation experiments.

• Journal of Electrochemical Science and Technology
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• v.12 no.3
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• pp.302-307
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• 2021

Polymer electrolyte membrane (PEM) electrolyzer or alkaline electrolyzer is required to produce green hydrogen using renewable energy such as wind and/or solar power. PEM and alkaline electrolyzer differ in many ways, instantly basic materials, system configuration, and operation characteristics are different. Building an optimal water hydrolysis system by closely grasping the characteristics of each type of electrolyzer is of great help in building a safe hydrogen ecosystem as well as the efficiency of green hydrogen production. In this study, the basic operation characteristics of a kW class alkaline water electrolyzer we developed, and water electrolysis efficiency are described. Finally, a brief overview of the characteristics of PEM and alkaline electrolyzer for large-capacity green hydrogen production system will be outlined.

• IE interfaces
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• v.14 no.4
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• pp.334-340
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• 2001

The theory of constraints (TOC) has become a valuable system in modern operations management. Using the ideas and methods of the TOC, companies can achieve a large reduction of work-in-process and finished-goods inventories, significant improvement in scheduling performance, and substantial earnings increase. The purpose of this paper is to calculate the optimal size of the time buffer which is used to accommodate disruptions in production processes and provide maximum productivity of capacity constrained resources. After the problem formulation in terms of single server queueing model, we observed the system behavior by sensitivity analyses.