• 자원ㆍ환경경제연구
• /
• 제29권3호
• /
• pp.363-388
• /
• 2020

본 연구의 목적은 다수어업에 의해 어획되는 삼치어종에 대해 잉여생산모형을 이용하여 최대지속적어획량(Y_MSY) 및 최대지속적어획노력량(F_MSY)을 추정한 후 현재 가치 해밀토니안 기법을 적용하여 삼치어종을 어획하는 다수어업의 이윤 극대화를 위한 최적어업관리 수준과 민감도 분석을 통한 삼치어종의 제도적 접근 방안을 제공함에 있다. 분석 내용으로, 우선, 다수어업의 어획노력량을 Gavaris의 일반선형모형을 적용하여 하나의 단위로 표준화한 후, 다양한 잉여생산모형 중 CYP 모형을 채택하여 정태적 자원평가를 시도하였다. 다음으로, 생물·기술적 계수와 경제적 매개변수를 가지고 현재가치 해밀토니안 기법을 이용하여 어업 이윤을 극대화하는 동태적 최적 수준을 추정하였다. 분석 결과, 우선, MSY 수준과 이윤이 극대화되는 수준에서 우리나라 삼치자원은 남획되고 있는 것으로 분석되었다. 다음으로, 경제적 주요 변수인 생산가격과 단위당 어업비용 변화에 따른 민감도 분석을 시도해본 결과, 생산가격 및 어업비용이 변화할 때 삼치어종의 자원량이 민감하게 반응하는 것으로 나타났다. 특히, 실제 삼치어종에 대한 어획노력량이 과도하게 투입되고 있어, 동 자원의 남획으로 인해 삼치어종을 어획하는 쌍끌이대형저인망어업, 대형선망어업, 대형트롤어업의 경영에도 비효율성을 야기하고 있는 것으로 분석되었다. 결론적으로, 본 연구에서는 우리나라 연근해 수산자원의 회복과 TAC 총량규제의 정부 정책의 확대에 맞추어 삼치어종도 TAC 대상 품종에 포함하여 체계적으로 자원을 관리해 나가길 제안하였다.

• Biotechnology and Bioprocess Engineering:BBE
• /
• 제10권1호
• /
• pp.78-84
• /
• 2005

The purpose of this study was to optimize the solid state cultivation of Monascus ruber on sterile rice. A single-level-multiple-factor and a single-factor-multiple-level experimental design were employed to determine the optimal medium constituents and to optimize carbon and nitrogen source concentrations for lovastatin production. Simultaneous quantitative analyses of the ${\beta}$-hydroxyacid form and ${\beta}$-hydroxylactone for of lovastatin were performed by the high performance liquid chromatography (HPLC) method with a UV photodiode-array (PDA) detector. The total lovastatin yield ($4{\sim}6\;mg/g$, average of five repeats) was achieved by adding soybean powder, glycerol, sodium nitrate, and acetic acid at optimized levels after 14 days of fermentation. The maximal yield of lovastatin under the optimal composition of the medium increased by almost 2 times the yield observed prior to optimization. The experimental results also indicated that the ${\beta}$-hydroxylactone form of lovastatin (LFL) and the ${\beta}$-hydroxyacid form of lovastatin (AFL) simultaneously existed in solid state cultures of Monascus ruber. while the latter was the dominant form in the middle-late stage of continued fermentation. These results indicate that optimized culture conditions can be used for industrial production of lovastatin to obtain high yields.

• 한국미생물·생명공학회지
• /
• 제16권6호
• /
• pp.450-456
• /
• 1988

대장균 변이주를 이용한 L-트립토판의 최적생산을 위해 목적산물의 생산과 유기산의 생성과의 상호관계를 조사한 결과 비 산생성속도(specific acid production rate)가 증가할수록 L-트립토판의 생산이 감소하는 것으로 나타났다. 따라서 L-트립토판 발효시 산의 생성량을 줄이기 위해 조절식 유가배양법을 도입하였는데 이 배양공정에서는 배양액내의 용존산소농도에 따라 영양배지의 유가속도를 조절하는 방식을 사용하여 세포증식속도를 제한, 세포의 산소요구량이 공급량을 초과하지 않도록 하였다. 이러한 조절식 유가배양법으로 대장균 세포를 배양한 결과 기존의 유가배양식에 비해 비 산생성속도가 현저하게 감소하였으며 L-트립토판의 생산은 5배 정도나 증가되었다.

• Journal of Microbiology and Biotechnology
• /
• 제18권5호
• /
• pp.913-917
• /
• 2008

The cyclic undecapeptide, cyclosporin A (CyA), is one of the most commonly prescribed immunosuppressive drugs. It is generated nonribosomally from a multifunctional cyclosporin synthetase enzyme complex by the filamentous fungus Tolypocladium niveum. In order to maximize the production of CyA by wild-type T. niveum (ATCC 34921), each of three culture stages (sporulation culture, growth culture, and production culture) were sequentially optimized. Among the three potential sporulation media, the SSMA medium generated the highest numbers of T. niveum spores. The SSM and SM media were then selected as the optimal growth and production culture media, respectively. The addition of valine and fructose to the SM production medium was also determined to be crucial for CyA biosynthesis. In this optimized three-stage culture system, 3% of the spore inoculum generated the highest level of CyA productivity in a 15-day T. niveum production culture, thereby implying that the determination of an appropriate size of T. niveum spore inoculum plays a critical role in the maximization of CyA production.

• 산업경영시스템학회지
• /
• 제10권16호
• /
• pp.143-147
• /
• 1987

Safety stocks constitute one of the major means of dealing with the uncertainties associated with variation in demand and lead time. Adeguate safety facilitate production activities and help to assure customers if good service on the other hand, carrying safety storks ties up working capital on goods that sit idle. The major problem of safety stocks management thus of consists of trying to achieve an optimal balance between the other carrying cost and the costs of stock shortage. Therefore, this study aims to find safety stock level of the fixed reorder quantity system and the fixed reorder cycle system of minimizing total cost when both demand and lead time are variable. (The distribution of demand and lead time is a mere assumption that follows the normal distribution) The results can be summarized as follows. i) Safety factor on the safety stock is determined by carrying cost and the costs of stock shortage: An optimal safety stick=the costs of stork shortage($C_s$) (the carrying cost($C_h$)+the costs of stock storage($C_s$). ii) The safety stock level of the fixed reorder quantity system is ($a{\;}_p\sqrt{L}{\sigma}$) under uncertainties. iii) The safety stock level of the fixed reorder cycle system is ($a{\;}_p\sqrt{R+L{\sigma}}$) under uncertain demand and constant lead time. ($a{\;}_p\sqrt{L{\sigma}_d{\;^2+{\mu}^2L{\sigma}^2}$) under demand and lead time uncertainties.

• Journal of Microbiology and Biotechnology
• /
• 제19권4호
• /
• pp.378-386
• /
• 2009

A sequential optimization strategy, based on statistical experimental designs, is employed to enhance the production of alkaline protease by a Bacillus pseudofirmus local isolate. To screen the bioprocess parameters significantly influencing the alkaline protease activity, a 2-level Plackett-Burman design was applied. Among 15 variables tested, the pH, peptone, and incubation time were selected based on their high positive significant effect on the protease activity. A near-optimum medium formulation was then obtained that increased the protease yield by more than 5-fold. Thereafter, the response surface methodology(RSM) was adopted to acquire the best process conditions among the selected variables, where a 3-level Box-Behnken design was utilized to create a polynomial quadratic model correlating the relationship between the three variables and the protease activity. The optimal combination of the major medium constituents for alkaline protease production, evaluated using the nonlinear optimization algorithm of EXCEL-Solver, was as follows: pH of 9.5, 2% peptone, and incubation time of 60 h. The predicted optimum alkaline protease activity was 3,213 U/ml/min, which was 6.4 times the activity with the basal medium.

• Journal of Microbiology and Biotechnology
• /
• 제28권6호
• /
• pp.902-908
• /
• 2018

Optimization of the culture medium to maximize menaquinone-7 (MK-7) production by Bacillus subtilis strain KCTC 12392BP in static culture was carried out using statistical experimental methods, including one factor at a time, fractional factorial design, and response surface methodology (RSM). Maltose (carbon source), tryptone (nitrogen source), and glycerol (activator) were identified as the key medium components for MK-7 synthesis by the fractional factorial design, and were selected for statistical optimization by RSM. The statistical analysis indicated that, in the range that was studied, maltose, tryptone, and glycerol were all critical factors having profound effects on the production of MK-7, with their coefficients for linear and quadratic all significant at the p < 0.05 level. The established model was efficient and feasible, with a determination coefficient ($R^2$) of 0.9419. The predicted concentrations of maltose, tryptone, and glycerol in the optimal medium were determined as 36.78, 62.76, and 58.90 g/l, respectively. In this optimized medium, the maximum yield of MK-7 reached a remarkably high level of $71.95{\pm}1.00{\mu}g/ml$ after 9 days of static fermentation, which further verified the practicability of this optimized strategy.

• 한국경영과학회지
• /
• 제20권1호
• /
• pp.27-34
• /
• 1995

In this paper, we have developed a model to determine the input quantity to be processed at each stage of a multi-stage production system in which the yield at each stage may be random and may need reworking at this stage. Yield randomness. especially in a semiconductor industry, is a most challenging problem for production control. The demand for flnal product is uncertain. We have extended the model proposed in Park and Kim[9] to consider a multiple number of reworkings which can be done at any stage prior to or tat the stage whose output in bad, depending on the level of the defect.

• KSBB Journal
• /
• 제29권3호
• /
• pp.165-178
• /
• 2014

Statistical medium optimization has been carried out for the production of succinic acid in anaerobic fermentations of Actinobacillus succinogenes. Succinic acid utilized as a precursor of many industrially important chemicals is a fourcarbon dicarboxylic acid, biosynthesized as one of the fermentation products of anaerobic metabolism by A. succinogenes. Through OFAT (one factor at a time) experiments, corn steep liquor (CSL), a very cheap agricultural byproduct, was found to have significant effects on enhanced production of succinic acid, when supplemented along with yeast extract. Hence, using these factors including glucose as a carbon/energy source, interactive effects were investigated through $2^n$ full factorial design (FFD) experiments, showing that the concentration of each component (i.e., glucose, yeast extract and CSL) should be higher. Further statistical experiments were conducted along the steepest ascent path, followed by response surface method (RSM) in order to find out optimal concentrations of each constituent. Consequently, optimized concentrations of glucose, yeast extract and CSL were observed to be 180 g/L, 15.08 g/L and 20.75 g/L respectively (10 g/L of $NaHCO_3$ and 100 g/L of $MgCO_3$ to be supplemented as bicarbonate suppliers), with the estimated production level of succinic acid to be 92.9 g/L (about 3.5 fold higher productivity as compared to the initial medium). Notably, the RSM-estimated production level was almost similar to the amount of succinic acid (92.9 g/L vs. 89.1 g/L) produced through the actual fermentation process performed using the statistically optimized production medium.

• International Journal of Industrial Entomology and Biomaterials
• /
• 제35권2호
• /
• pp.111-117
• /
• 2017

Mulberry leaves containing 1-deoxynojirimycin (DNJ) known to be a strong inhibitory effect for ${\alpha}-glucosidase$. Thus, DNJ has been recognized as a potentially important source for prevent or treat hyperglycemia. More effective method for the DNJ high-production is needed because DNJ content of natural mulberry leaf are as low as 0.1%. Many researchers have studied for the DNJ high-production in mulberry leaves such as the harvest season, fermentation using microorganisms, optimal culture conditions, and optimal extraction conditions. In order to provide for useful data that is anticipated at the level of industrial scale, we investigated ${\alpha}-glucosidase$ inhibitory activity, pH value and DNJ content in large-scale based on the optimal culture conditions for mulberry leaf fermentation of small-scale in our previous study. The ${\alpha}-glucosidase$ inhibitory activity, pH value, and DNJ content in this study were measured from the mulberry leaf fermentation broth for 7 days. During mulberry leaf fermentation, the ${\alpha}-glucosidase$ inhibitory activity and DNJ content was increased until 2 to 4 days, but after 4 day was decreased. The pH value showed a decreasing trend up to 2 day, and little changes in 2 to 4 days. However, the pH was started to increase after 4 days.