• Journal of Microbiology and Biotechnology
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• v.12 no.6
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• pp.962-971
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• 2002

The current study proposes a simple monodimensional model to estimate the linear growth rate of photosynthetic microorganisms in flat-plate photobioreactors (FPPBRs) during batch cultivation. As a model microorganism, Chlorella kessleri was cultivated photoautotrophically in FPPBRs using light-emitting diodes (LEDs) as the light sources to provide unidirectional irradiation in the photobioreactors. Various conditions were simulated by adjusting both the intensity of the light and the height of the culture. The validity of the proposed model was examined by comparing the linear growth rates measured with the predicted ones obtained from the proposed model. Accordingly, the value of $\frac{K\cdot\mu m}{\alpha\cdot L}log(I_0\cdot{I_s}^{\varepsilon 1)\cdot {I_c}^{-\varepsilon})$ was proposed as an approximate index for strategies to obtain the maximal lightn yield under light-limiting conditions for high-density algal cultures and as a control parameter to improve the photosynthetic productivity and efficiency.

• 한국생물공학회:학술대회논문집
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• 2005.10a
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• pp.511-516
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• 2005

Sorbitan methacrylate was synthesized from sorbitan dehydrated from D-sorbitol using an immobilized lipase. To optimize the enzymatic synthesis of sorbitan methacrylate, response surface methodology was applied to determine the effects of five-level-four-factors and their reciprocal interactions on sorbitan methacrylate biosynthesis. A total of 30 individual experiments were performed, which were designed to study reaction temperature, reaction time, enzyme amount and substrate molar ratio. A statistical model predicted that the highest conversion yield of sorbitan methacrylate was 100%, at the following optimized reaction conditions: a reaction temperature of 43.06 $^{\circ}C$, a reaction time of 164.25 mins., an enzyme amount of 7.47%, and a substrate molar ratio of 3.98:1. Using these optimal factor values under experimental conditions in four independent replicates, the average conversion yield reached 98.7%${\pm}$1.2% and was well within the value predicted by the model.

• Journal of Microbiology and Biotechnology
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• v.18 no.5
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• pp.918-925
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• 2008

Controlling the light energy and major nutrients is important for high cell density culture of cyanobacterial cells. The growth phase of Anabaena variabilis can be divided into an exponential growth phase and a deceleration phase. In this study, the cell growth in the deceleration phase showed a linear growth pattern. Both the period of the exponential growth phase and the average cell growth rate in the deceleration phase increased by controlling the light intensity. To control the light intensity, the specific irradiation rate was maintained above $10\;{\mu}mol/s/g$ dry cell by increasing the incident light intensity stepwise. The final cell density increased by controlling the nutrient supply. For the control of the nutrient supply, nitrate, phosphate, and sulfate were intermittently added based on the growth yield, along with the combined control of light intensity and nutrient concentration. Under these control conditions, both final cell concentration and cell productivity increased, to 8.2 g/l and 1.9 g/l/day, respectively.

• Biotechnology and Bioprocess Engineering:BBE
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• v.10 no.6
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• pp.522-527
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• 2005

Various processes which produce L-lactic acid using ammonia-tolerant mutant strain, Rhizopus sp. MK-96-1196, in a 3L airlift bioreactor were evaluated. When the fed-batch culture was carried out by keeping the glucose concentration at 30g/L, more than 140 g/L of L-lactic acid was produced with a product yield of 83%. In the case of the batch culture with 200g/L of initial glucose concentration, 121g/L of L-lactic acid was obtained but the low product yield based on the amount of glucose consumed. In the case of a continuous culture, 1.5g/L/h of the volumetric productivity with a product yield of 71% was achieved at dilution rate of $0.024\;h^{-1}$. Basis on these results three processes were evaluated by simple variable cost estimation including carbon source, steam, and waste treatment costs. The total variable costs of the fed-batch and continuous cultures were 88% and 140%, respectively, compared to that of batch culture. The fed-batch culture with high L-lactic acid concentration and high product yield decreased variable costs, and was the best-suited for the industrial production of L-lactic acid.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.51 no.3
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• pp.313-320
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• 2018

Chub mackerel Scomber japonicus is an economically important pelagic species in the western North Pacific. In the last 50 years, the annual total catch in Korean waters showed large fluctuations, ranging from 100 to $420{\times}10^3tons$. To provide a biological reference point for management of chub mackerel, we applied a simulation-based yield-per-recruit (Y/R) model that considered both temperature-dependent growth and size-dependent mortality. We estimated the fisheries yield with respect to varying biological reference points and environmental conditions, including 1) the instantaneous rate of fishing mortality (F), 2) length of fish at first capture ($L_c$), and 3) water temperature. The result of our analysis showed that the Y/R could be greatest when the $L_c$ ranges from 19-27 cm and F ranges from $1.48-2.00yr^{-1}$. Y/R increases with increased water temperature between 15 and $23^{\circ}C$. We suggest targeting an $L_c$ of 17 cm (age=0.6 years) under the assumed current of $F=0.48yr^{-1}$ for maximizing the chub mackerel harvest. Further analysis considering spawning and recruitment processes are required to provide biological reference points to ensure the sustainability of chub mackerel fisheries in Korean waters.

• Korean Journal of Medicinal Crop Science
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• v.10 no.2
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• pp.126-131
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• 2002

We investigated the high yield capacity of Hwangchil lacquer for selection and identification of major aromatic components of the selected trees as well. The Hwangchil lacquer showed the difference yields by different habitat, tree ages and individual character. The selected trees showed high yield capacity of Hwangchil lacquer. We also investigated the essential oil contents and its the main components to analysis the potent of mass propagation. The major compounds were 1,6-atadiene-3-ol., ${\alpha}-terpinene,\;{\alpha}-cubebene,\;{\alpha}-ylangene,\;{\alpha}-copane,\;{\beta}-elemene,\;germacrene-D,\;{\beta}-selinene,\;{\alpha}-selinene,\;{\delta}-cadinene,{\gamma}-cardinene$, germacrene B, germacrene D-4-ol. The most principle component was germacrene D among them respectively. However, the difference of relative content ratio of each major compound was showed by individuals, population and native areas in the selected trees.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.56 no.3
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• pp.331-340
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• 2023

To estimate the biological reference points, suitable for fisheries management of sandfish Arctoscopus japonicas in the East Sea of Korea, we simulated the yield-per-recruit (Y/R) from age 0 to 6 (0-2,555 days). The stimulation was based on two instantaneous natural mortality conditions: size-dependent (M_t, d^-1) and constant (M_cons, d^-1); Subsequently, the biological reference points of the two mortality conditions was compared. M_t decreased from 0.0075 d^-1 to 0.0018 d^-1 depending on growth, and M_cons remained constant at 0.0011 d^-1 for all ages. Our Y/R model showed that the maximum yield of M_cons was 14 times higher than that of the M_t. The length at first capture to maximize the harvest at the F_0.1 points of the two natural mortality conditions was L_c,t=10.2 cm (TL) and L_c,cons=17 cm (TL). We concluded that M_t was more suitable for estimating M than M_cons; this is because L_c,t showed minimal difference from the current fishing regulations (11 cm, TL), and M_t reflected more biological characteristics than M_cons. We suggest that 10.2 cm and 0.8 as the suitable length at first capture and corresponding age, respectively for efficient fisheries management of sandfish.

• Fisheries and Aquatic Sciences
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• v.27 no.6
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• pp.392-409
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• 2024

The present study aims to analyze the biological aspects and population dynamics of Indian mackerel in Barru waters. Data was collected in Barru for 11 months, from June 2022 to April 2023. The observed parameters of biological aspects included gonadal maturation stages (GMSs), size at first gonadal maturation, and length-weight relationship. Meanwhile, the aspects of population dynamics encompass age group, growth, mortality rate, and exploitation rate. Data analysis consisted of morphological selection of general maturation stages, Spearman-Kärber method in estimating gonadal first maturation size, Bhattacharya method in identifying age group, von Bertalanffy function through FISAT II to measure growth (L_∞ and K), Pauly Model to estimate mortality rate, Beverton & Holt Model to estimate Y/R, and virtual population analysis (VPA) analysis to estimate stock and fish yield. The results demonstrated that GMS I was observed to be dominant, followed by stages II and III. The initial gonadal maturation was estimated to be 17.98-19.28 cm (FL) for females and 17.98-19.27 cm (FL) for males. The length-weight relationship in male and female Indian mackerels indicated a positive allometric growth. The mode grouping analysis results from the fork length measurement revealed three age groups. It was also identified that the asymptotic length (L_∞) = 29.5 cm (fork length), growth rate coefficient (K) = 0.46 per year, and theoretical age at zero length (t₀) = -0.3576 per year. Total mortality (Z) = 2.67 per year, natural mortality (M) = 1.10 per year, fishing mortality (F) = 1.57 per year, and exploitation rate (E) = 0.59, the actual Y/R = 0.083 gram/recruitment, and optimal Y/R 0.03 gram/recruitment. Fishing mortality is higher than the natural mortality rate, and a high exploitation value (E > 0.5) also reflects over-exploitation. VPA analysis on fish yields and stock estimation reported a highly exploited rate between the 11.5 cm and 14.5 cm length classes and an exceeding current yield of 467.07 tons/year with a recommended yield of 233.53 tons/year to ensure population sustainability.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.50 no.5
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• pp.340-345
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• 2005

A field experiment was conducted to assess the growth characteristics, seed and oil yield of two cultivars of soybean (G max (L.) Merr.) cv. PK-416 ($V_1$) and cv. PK-1024 ($V_2$) in relation to sulphur and nitrogen nutrition. Six combinations ($T_1-T_6$) of two levels of sulphur (0 and 40 kg $ha^{-1}$) and two levels of nitrogen (23.5 and 43.5 kg $ha^{-1}$) were applied to the two soybean cultivars as nutrients. Results indicated significant effect of sulphur and nitrogen, when applied together, on the growth characteristics, yield components, and seed and oil yield. Maximum response was observed with treatment $T_6$ (having 40 kg S and 43.5 kg N $ha^{-1}$). Seed and Oil yields were increased 90 and $102\%$ in $V_1$> and 104 and $123\%$ in $V_2$, respectively as compared to the control i.e. $T_1$ (having 0 kg S and 23.5 kg N $ha^{-1}$). Positive responses of S and N interaction on leaf area index, leaf area duration, crop growth rate and biomass production were also observed. The results obtained in these experiments clearly suggest that balanced and judicious application of nitrogen and sulphur can improve both seed and oil yield of soybean cultivars by enhancing their growth.

• Korean Journal of Ecology and Environment
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• v.44 no.2
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• pp.172-177
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• 2011

The study sought to determine the efficient management of Korean aucha perch by estimating the potential yield (PY), which means the maximum sustainable yield (MSY) based on the optimal stock, in the mid-upper region of the Seomjin River watershed from August 2008 to April 2009. The stock assessment was conducted by the swept area method and PY was estimated by a modified fisheries management system based on the allowable biological catch. Also, the yield-per-recruit analysis (Beverton and Holt, 1957) was used to review the efficient management of resource, Coreoperca herzi. The age at first capture ($t_c$) was 1.464 age and converted body length was 7.8 cm. Concerning current fishing intensities, the instantaneous coefficient of fishing mortality (F) was estimated to be 0.061 $year^{-1}$; yield-per-recruit analysis estimated the current yield per recruit as 4.124 g with F and $t_c$. The fishing mortality of Allowable Biological Catch ($F_{ABC}$) based on the current $t_c$ and F was estimated to be 0.401 $year^{-1}$, therefore, the optimum fishing intensities could be achieved at the higher fishing intensity for Coreoperca herzi. The calculated annual stock of Coreoperca herzi was 3,048 kg, the potential yield was estimated to be 861 kg with $t_c$ and $F_{ABC}$ at the fixed current level. Using yield-per-recruit analysis, if F and $t_c$ were set at 0.643 $year^{-1}$ and 3 age, respectively, the yield per recruit would be predicted to increase 3.4-fold, from 4.12 g to 13.84 g.