• Korean Journal of Ecology and Environment
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• v.37 no.1 s.106
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• pp.57-63
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• 2004

Primary productivity of phytoplankton was measured by $^{14}C$ method from January to October of 1996 in Seonakdong River. This river was a highly productive freshwater showing the euphotic depth of 1.4 m in August and 2.1 m in the remaining season. Chlorophyll-a concentrations of phytoplankton ranged from 67 ${\mu}g\;L^{-1}$ to 894 ${\mu}g\;L^{-1}$ and showed the great increase in August. Maximum specific productivity was 2.1 ${\sim}$4.3 mg C mg $chl-a{-1}\;hr^{-1}$ and occurred above 0.4m depth. In photosynthesis-irradiance relation, photoinhibition or photosynthetic suppression of phytoplankton occurred clearly in the cold seasons, while phytoplankton (mainly Microcystis aeruginosa and its relatives) in August did not show any symptom of the photosynthetic inhibition against the high irradiance. The specific productivity of phytoplankton was eventually dependant upon incident irradiance to show the linear correlation with received irradiance infield, and the areal productivity of phytoplankton upon chlorophyll-a standing crops. In the downstream of the Nakdong River, phytoplankton productions have linearly increased since the estuarine barrage construction to reflect the gradual eutrophication in the estuarine area. Average chlorophyll-a increase of 10 ${\mu}g\;chl-a\;L{-1}$ absolutely corresponded to the primary production acceleration of 30 mg C $m^{-2}\;day^{-1}$ on the annual basis.

• Lingua Humanitatis
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• v.1 no.1
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• pp.235-251
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• 2001

According to Chomskyan grammar, humans can generate and understand an unbounded number of grammatical sentences. Against the background of pure and idealized linguistic competence, this linguistic productivity is argued and understood. In actual utterances, however, there are many limitations of productivity but they are said to come from the general constraints on performances such as capacity of short term memory or attention. In this paper I discuss a problem raised against idealized productivity. I argue that linguistic productivity idealizes our linguistic competence too much. By separating idealized competence from the various constraints of performance, Chomskyan theorists can argue for unlimited productivity. However, the absolute distinction between grammar (pure competence) and parser (actual psychological processes) makes little sense when we explain the low acceptability(intelligibility) of center embedded sentences. Usually, the problem of center embedded sentence is explained in terms of memory shortage or other performance constraints. To explain the low acceptability, however, we need to assume specialized memory structure because the low acceptability occurs only with a specific type of syntactic pattern. 1 argue that this special memory structure should not be considered as a general performance constraint. It is a domain specific (specifically linguistic) constraints and an intrinsic part of human language processing. Recent development of Chomskyan grammar, i.e., minimalist approach seems to close the gap between pure competence and this type of specialized constraints. Chomsky's earlier approach of generative grammar focuses on end result of the generative derivation. However, economy principle (of minimalist approach) focuses on actual derivational processes. By having less mathematical or less idealized grammar, we can come closer to the actual computational processes that build syntactic structure of a sentence. In this way, we can have a more concrete picture of our linguistic competence, competence that is not detached from actual computational processes.

• Korean Journal of Construction Engineering and Management
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• v.15 no.4
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• pp.30-38
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• 2014

Achieving high productivity and constructability are very important issues in construction industry. Study on constructability have been conducted actively, and many researches referred that improving constructability can enhance cost, quality, schedule, productivity and so on. However, there are lack of quantitative analysis, since most studies have proved correlation between productivity and constructability using questionaries and by case studies. Also, researches are mostly about specific detail scope of work to improve constructability, thus it is hard to apply constructability factors on various work in construction. In this paper, will deduct general factors affecting on constructability and evaluate effects of factors affecting on each work. Furthermore this paper will verify impact of factors affecting on productivity by multi regression anlaysis using actual data sets of high-rise building construction site.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.4 no.2
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• pp.136-143
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• 1999

To understand the growth of attached microalgae to the immersed artificial surfaces in seawater with exposure time, chlorophyll a (chl a) concentration and abundance of attached microalgae to glass slides, and primary productivity and chl a concentration on coverglasses were investigated in Incheon Harbour in May, June 1996 and January-February 1997. Chl a concentrations of microalgae and abundances of diatoms attached to glass slides reached 62.5 mg chl a $m^{-2}$ and $144{\times}10^3$ cells $cm^{-2}$, respectively, during the study period. Chl a concentrations increased with exposure time, and they were significantly correlated with the abundances of attached diatoms ($r^2=0.79$, p<0.001). The chl a concentrations of attached micro algae on coverglass reached the maximum values of 31.1 mg chl a $m^{-2}$ and 65.4 mg chl a $m^{-2}$, and then decreased in May, June 1996. But in January-February 1997, the chl a concentration increased continuously up to 98.9 mg chl a $m^{-2}$. The primary productivity reached the maximum values of 63.1 mgC $m^{-2}\;h^{-1}$, 347.0 mgC $m^{-2}\;h^{-1}$ and 78.3 mgC $m^{-2}\;h^{-1}$, respectively, in May, June and January-February. The primary productivity in May and June varied in accordance with chl a concentrations. But in January-February, the primary productivity decreased from 26 days of exposure while chl a concentration continued to increase. Two cases that primary productivity decreased abruptly seemed to be caused by decrement of chl a and light specific $P^B$ (chl a specific primary productivity) (May and June) and by decrement of light specific $P^B$ due to photoinhibition (January-February). The results of present study indicated that chl a concentrations and the primary productivity of microalgae attached to artifical surfaces immersed in seawater would expedite analysis of dynamics of biomass and physiological status of attached microalgae during biofilm formations.

• Microbiology and Biotechnology Letters
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• v.18 no.4
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• pp.394-400
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• 1990

Maximization of productivity of recombinant cell fermentations requires consideration of the inverse relationship between the host cell growth rate and product formation rate. The problem of maximizing a weighted performance index was solved by using optimal control theory for recombinant E. coli fermentation. Concentration of a growth inhibitor was used as a control variable to manipulate the specific growth rate, and consequently the cloned-gene expression rate. Using a simple unstructured model to describe the main characteristics of this system, theoretical analysis showed that the optimal control profile results in an initial high growth rate phase followed by a low growth rate and high product formation rate phase. Numerical calculations were done to determine optimal switching times from the growth to the production stage for two representative cases corresponding to different dependency of the product formation rate on the growth rate. For the case when product formation rate is sensitive to the specific growth rate, the optimized operation yields about 60% increase in the final product concentration compared with a simple batch fermentation.

• BMB Reports
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• v.57 no.1
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• pp.50-59
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• 2024

The application of gene engineering in livestock is necessary for various reasons, such as increasing productivity and producing disease resistance and biomedicine models. Overall, gene engineering provides benefits to the agricultural and research aspects, and humans. In particular, productivity can be increased by producing livestock with enhanced growth and improved feed conversion efficiency. In addition, the application of the disease resistance models prevents the spread of infectious diseases, which reduces the need for treatment, such as the use of antibiotics; consequently, it promotes the overall health of the herd and reduces unexpected economic losses. The application of biomedicine could be a valuable tool for understanding specific livestock diseases and improving human welfare through the development and testing of new vaccines, research on human physiology, such as human metabolism or immune response, and research and development of xenotransplantation models. Gene engineering technology has been evolving, from random, time-consuming, and laborious methods to specific, time-saving, convenient, and stable methods. This paper reviews the overall trend of genetic engineering technologies development and their application for efficient production of genetically engineered livestock, and provides examples of technologies approved by the United States (US) Food and Drug Administration (FDA) for application in humans.

• KSBB Journal
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• v.7 no.4
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• pp.247-251
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• 1992

The effect of biomass concentration of Saccharomyces cerevisiae ATCC 24858 on specific growth rates, biomass yields, ethanol yields and productivity in the batch fermentation of rotary shaker was investigated. The specific growth rate decreased according to the increase in the biomass density and finally became zero at a biomass concentration, 55g/L. The ethanol yield $Y_{p/s}$ represented a constant value, 0.43, regardless of the change of biomass concentrations. However, the biomass yield $Y_{x/s}$ showed a trend to diminish in values with augmentation of biomass density and ultimately to reach zero at 55g/L of biomass concentration. The ethanol productivity increased linearly with biomass concentration so that, in case of initial sugar concentration, 170g/L, the productivity for 55g/L of biomass density rose up to 30g/L$\cdot$hr for all the batch fermentations. And also the ethanol concentration inhibiting completely the growth was verified 95g/L by applying experimental data to Luong's equation.

• Journal of Microbiology and Biotechnology
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• v.16 no.1
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• pp.20-24
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• 2006

Plasmid DNA (pDNA) is a product of interest for many biopharmaceutical companies and research laboratories, because of increase in the number of gene therapy protocols that use nonviral vectors. This work was undertaken to study the effect of antibiotic and dissolved oxygen concentration (DOC) on the production of a ColE 1-type plasmid (pVAX1-LacZ) hosted in Escherichia coli $DH5\alpha$ and cultured in a batch fermentor with 0.751 of Terrific Broth. A decrease in the DOC from $60\%\;to\;5\%$ was shown to increase the specific pDNA concentration approximately 1.5-fold, due to the downregulation of growth. Additionally, this increase in the pDNA concentration led to a 2.2-fold increase in the purity of cell lysates obtained after cell lysis. However, the use of higher DOC led to 2.8-fold higher volumetric productivity as a consequence of a faster growth rate, reducing the fermentation time from 24 to 8 h. Interestingly, the specific pDNA concentration, and pDNA productivity and purity were always higher $(10-15\%)$ in the absence of antibiotic. Overall, the data indicate that nonselective conditions can be used without compromising yield, productivity, and purity of pDNA.

• Journal of Microbiology and Biotechnology
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• v.18 no.6
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• pp.1186-1190
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• 2008

Single-chain Fv (scFv) antibody against c-Met is expected to be employed in clinical treatment or imaging of cancer cells owing to the important biological roles of c-Met in the proliferation of malignancies. Here, we show that the productivity of scFv against c-Met in Escherichia coli is significantly influenced by the orientation of its variable domains. We generated anti-c-Met scFv antibodies with two different domain orders (i.e., $V_L$-linker-$V_H$ and $V_H$-linker-$V_L$), expressed them in the cytoplasm of E. coli trx/gor deleted mutant, and compared their specific activities as well as their productivities. Productivity of total and functional anti-c-Met scFv with $V_H/V_L$ orientation was more than five times higher than that with $V_L/V_H$ format. Coexpression of DsbC enhanced the yield of soluble amounts of anti-c-Met scFv protein for both constructs. The purified scFv antibodies of the two different formats exhibited almost the same antigen-binding activities. We also compared the productivities and specific activities of anti-c-Met diabodies with $V_H/V_L$ or $V_L/V_H$ formats and obtained similar results to the case of scFv antibodies.

• KSBB Journal
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• v.8 no.2
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• pp.164-171
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• 1993

The production of extracellular polysaccharide by Methylomonas mucosa (NRRL B-5696) was investigated. The microorganism uses methanol as the carbon source for their growth and produces exopolysaccharides. The productivity of exopolysaccharides was investigated under various culture modes: batch, fed-batch and continuous culture. In flask culture the growth of cell mass and the production of polysaccharide were inhibited at above 1% (v/v) methanol. At 1%(v/v) methanol maximum specific growth rate was obtained. As C/N ratio (g methanol/g ammonium sulfate) increased, polysaccharide production increased and cells mass decreased. Magnesium ion was also found to be essential for the polysaccharide production. In batch culture the production of polysaccharides was more affected by the specific growth rate than the cell concentration. In fed-batch culture the concentration of polysaccharide was 4 times higher than that of batch culture, but the yield was lower. The productivity of fed-batch with continuous feeding was higher than that of batch or fed-batch with intermittent feeding. This is due to no methanol limitation or inhibition that used to occur in fed-batch culture with intermittent feeding. In continuous culture pure oxygen was supplied to avoid the oxygen limitation. As the dilution rate in- creased up to 0.21 h-1, the yield and productivity increased. The solution viscosity of the produced polysaccharide obtained from above increased exponentially with the concentration of polysaccharide.