• The Journal of Fisheries Business Administration
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• v.43 no.1
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• pp.1-9
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• 2012

Based on Clark and Munro's theory of dynamic optimization between fishery resources and production, this study is aimed to take an empirical analysis of optimal production level to the Danish Seine fishery under the sandfish stock rebuilding plan. For empirical analysis, it examined the optimal fish stock size, production and fishing effort levels and it also made an additional evaluation of optimal production changes on main variables by sensitivity analyses. When a 4% of the discount rate is assumed, the optimal sandfish production of Danish Seine fishery would be 3,049 t, and the sandfish optimal stock size is evaluated to be 19,016 t. In addition, the optimal fishing effort is estimated to be 4,368 days. Accordingly, to achieve the optimal production level, current fishing efforts should be reduced while the fish stock size should be increased up to the optimal level.

• Journal of Korean Society for Quality Management
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• v.47 no.1
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• pp.87-96
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• 2019

Purpose: The purpose of this paper is to determine an optimal production time for economic production quantity model with preventive maintenance and random defective rate as the function of a machinery deteriorates. Methods: If a machinery shifts from "in-control" state to "out-of-control" state, a proportion of defective items being produced increases. It is assumed that time to state shift is a random variable and follows an arbitrary distribution. The elapsed time until process shift decreases stochastically as a production cycle repeats and quasi-renewal process is used to implement for production facilities to deteriorate. Results: When the exponential parameter for exponential distribution increases, the optimal production time increases. When Weibull distribution is considered, the optimal production time is closely affected by the shape parameter of Weibull distribution. Conclusion: A mathematical model is suggested to find optimal production time and optimal number of production cycles and numerical examples are implemented to validate the patterns for changes of optimal times under different parameters assumptions. The real application is implemented using the proposed approach.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.298-301
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• 1996

This paper addresses the effects of an imperfect production process on the optimal production quantity and quality inspection policies. The system is assumed to deteriorate during the production process. The results are either defective products or machine breakdown whether multiple quality inspection is worth or not. Furthermore, when multiple inspection policy is adopted, the optimal inspection schedule is shown to be equally spaced throughout the production cycle. Exact solution and approximation of the optimal production quantity and approximation of the optimal number of inspection are provided. Finally, to better understand the model of this paper, comparisons between this model and classical EMQ model are provided.

• Korean Journal of Microbiology
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• v.40 no.2
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• pp.160-166
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• 2004

The optimal conditions for production of Monascus sp. KM100l cell mass on submerged culture and production of monacolin K on rice solid culture were investigated. An overproducing mutant of Monascus pigments, KM 1001 mutant, from Monascus purpureus KCCM60016 was selected by NTG treatment. The optimal medium for the production of KM100l mutant cell mass is instructed to be composed of 3% glucose, 2% yeast extract, 0.1 % KH$_2$PO$_4$, 0.05% The optimal conditions for production of Monascus sp. KM100l cell mass on submerged culture and production of monacolin K on rice solid culture were investigated. An overproducing mutant of Monascus pigments, KM 1001 mutant, from Monascus purpureus KCCM60016 was selected by NTG treatment. The optimal medium for the production of KM100l mutant cell mass is instructed to be composed of 3% glucose, 2% yeast extract, 0.1 % KH$_2$The optimal conditions for production of Monascus sp. KM100l cell mass on submerged culture and production of monacolin K on rice solid culture were investigated. An overproducing mutant of Monascus pigments, KM 1001 mutant, from Monascus purpureus KCCM60016 was selected by NTG treatment. The optimal medium for the production of KM100l mutant cell mass is instructed to be composed of 3% glucose, 2% yeast extract, 0.1 % $(KH_2PO_4$, 0.05% $MgSO_4{\cdot}7H_2O$, 0.2% L-asparagine, pH 4.5, and the optimal inoculum size and shaking speed were $1.5{\times}10^6$ spores/50 m1 medium and 150 rpm, respectively. On optimal conditions, 4.1 g/l of the cell mass was obtained at 28$^{\circ}C$ for 3 days. The mycelium were inoculated on 500 g of steamed rice using vinyl bag ($30.6{\times}44$ cm) and incubated at $30^{\circ}C$, 85% humidity for 21 days. Lactone form monacolin K was rapidly increased for 2 days and reached highest concentration of monacolin K (2,930 mg/kg) for 15 days, and monacolin K was decreased after 15 days.

• Journal of Life Science
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• v.9 no.2
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• pp.5-8
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• 1999

We isolated a sphingonyelinase (SMase) inhibitor, which would be a potential reagent to regulate cell proliferation, oncogenesis, and inflammation, from a strain of Streptomyces sp.. In this paper, we report the optimal conditions for the production of SMase inhibitor, designed as sphinin, from Streptomyces sp. F50970. The optimal carbon and nitrogen source were 1% soluble starch and 0.05%-0.15% trypton. Most of monosaccharides and high concentration of soluble starch above 1.0% caused falling of pH and sphinin production. Zn2+, Cu2+, Fe2+, Mn2+, and Co2+inhibited cell growth and the production of sphinin. Inorganic phosphate promoted the sphinin production. Optimal initial pH for the production of sphinin was 7.5-8.0. Addition of CaCO3 to the medium resulted in an increase of inhibitor production. Based on these results, we designed a fermentation medium for the production of a SMase inhibitor, sphinin, from Streptomyces sp. F50970.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.22 no.1
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• pp.313-320
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• 2021

This study develops a demand and supply model and price model for Miryang sesame leaf cultivation and predicts the optimal production level to maximize total profit for Miryang sesame leaf farms. We used time series data from 1996 to 2017, which are related to Miryang sesame leaf cultivation. For the analysis, we estimated the demand function and average cost function, calculated the optimal production level and price, and derived the optimal profit. In addition, we predicted the optimal production level, price, total revenue, total cost, and profit until the year 2030 through scenario analysis. The results show that the optimal production level until the year 2030 is between 10 and 12.5 thousand tons, while the production volume was 7 thousand tons in 2017, and total profit for Miryang sesame leaf farms is estimated at 13.3 to 21.3 billion Korean won in 2030. The producer group needs to maintain the optimal production level to maximize total profit for farmers, as suggested in this study.

• The Korean Journal of Food And Nutrition
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• v.11 no.6
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• pp.612-616
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• 1998

Optimal media and cultural conditions for the production of red pigment were established using Monasurs anka KFCC 4478. The optimal temperature and initial pH for the production of red pigment were 30$^{\circ}C$ and 7.0, respectively. Glucose turned out to be most suitable carbon source for red pigment production. Optimal glucose concentration was 3.0%. Addition combined of nitrogen sources of peptone and NaNo3 induced good red pigment production. Thiamine-HCI and nicotinic acid were increased the production of red pigment. Under optimal conditions, maximum red pigment production and cell growth were observed after 5 days of incubation.

• Journal of the Korean Operations Research and Management Science Society
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• v.21 no.3
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• pp.143-157
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• 1996

This paper addresses the effects of an imperfect production process on the optimal production quantity and quality inspection policies. The system is assumed to deteriorate during the production process. The result are either the production of a number of defective items or the breakdown of the production meachine. A simple rule has been suggested to determine whether multiple quality in spection is workth or not. Furthermore, when multiple inspection policy is adopted, the optimal in spection schedule is shown to be equally spaced throughout the production cycle. Exact solution and approximation of the optimal production quantity and approximation of the optimal number of inspection are provided. Finally , to better understand the model of this paper, comparisons between this model and classical EMQ model are provided.

• The Journal of Fisheries Business Administration
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• v.46 no.2
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• pp.59-74
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• 2015

This study aims to estimate optimal harvesting production, fishing efforts, and stock levels of yellow croaker caught by the offshore Stow Net and the offshore Gill Net fisheries using the current value Hamiltonian method and the surplus production model. As analyzing processes, firstly, this study uses the Gavaris general linear model to estimate standardized fishing efforts of yellow croaker caught by the above multiple fisheries. Secondly, this study applies the Clarke Yoshimoto Pooley(CY&P) model among the various exponential growth models to estimate intrinsic growth rate(r), environmental carrying capacity(K), and catchability coefficient(q) of yellow croaker which inhabits in offshore area of Korea. Thirdly, the study determines optimal harvesting production, fishing efforts, and stock levels of yellow croaker using the current value Hamiltonian method which is including average landing price of yellow croaker, average unit cost of fishing efforts, and social discount rate based on standard of the Korean Development Institute. Finally, this study tries sensitivity analysis to understand changes in optimal harvesting production, fishing efforts, and stock levels of yellow croaker caused by changes in economic and biological parameters. As results drawn by the current value Hamiltonian model, the optimal harvesting production, fishing efforts, and stock levels of yellow croaker caught by the multiple fisheries were estimated as 19,173 ton, 101,644 horse power, and 146,144 ton respectively. In addition, as results of sensitivity analysis, firstly, if the social discount rate and the average landing price of yellow croaker continuously increase, the optimal harvesting production of yellow croaker increases at decreasing rate and then finally slightly decreases due to decreases in stock levels of yellow croaker. Secondly, if the average unit cost of fishing efforts continuously increases, the optimal fishing efforts of the multiple fisheries decreases, but the optimal stock level of yellow croaker increases. The optimal harvest starts climbing and then continuously decreases due to increases in the average unit cost. Thirdly, when the intrinsic growth rate of yellow croaker increases, the optimal harvest, fishing efforts, and stock level all continuously increase. In conclusion, this study suggests that the optimal harvesting production and fishing efforts were much less than actual harvesting production(35,279 ton) and estimated standardized fishing efforts(175,512 horse power) in 2013. This result implies that yellow croaker has been overfished due to excessive fishing efforts. Efficient management and conservative policy on stock of yellow croaker need to be urgently implemented.

• Microbiology and Biotechnology Letters
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• v.23 no.2
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• pp.220-228
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• 1995

For polyhydroxyalkanoic acid (PHA) production, several microorganisms were isolated from sewage sludge. One of them, GB-77 strain, was chosen from its PHB/HV copolymer production on only fructose without cosubstrate. The isolated strain GB-77 was identified as the genus Alcaligenes. Optimal temperature and pH for cell growth were 36C and 6.8. Optimal medium composition was 10 g/l of fructose and 5 g/l of polypeptone, 1 $\times$ 10$^{-2}$M Na$^{2}$HP0$^{4}$, 1.3 $\times$ 10$^{-2}$M KH$^{2}$PO$^{4}$. To investigate the optimal condition for polyhydroxyalkanoic acid production two-stage culture technique was used; first stage for cell growth and second stage for PHA production on unbalanced growth conditions. Optimal conditions for high PHA production were C/N ratio 50, temperature 36$\circ$C and pH 6.8. To overcome fructose inhibition on cell growth, intermittent feeding fed-batch culture technique was used. Total cell concentration was 17.4 g/l with 9.1 g/l of PHA. The purified PHA was identified PHB/HV copolymer by NMR analysis.