• 수산해양교육연구
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• 제28권6호
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• pp.1792-1800
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• 2016

This study is aimed to analyze the profitability of flatfish fry production farms in the Republic of Korea. The continuous and stable production of flatfish fries is one of important factors that increases the possibility of flatfish aquaculture's success. It is also the basis of aquaculture industry that estimates the quantity and quality of fishery products from aquaculture. Based on the surveyed data, production values and costs of flatfish fry production are estimated and compared to determine the profitability of flatfish fry production by farm. Results show that average return on sales of farms is 21.2%(12.4~26.3%), indicating that flatfish fry production would be profitable under the current production and market conditions. Sensitivity analyses of main variables (survival rate and selling price) indicate that the profitability of flatfish fry production farms can be significantly decreased when the survival rate and selling price would be slightly decreased.

• Asian-Australasian Journal of Animal Sciences
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• 제25권5호
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• pp.653-658
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• 2012

This study was conducted to estimate the potential acid production value (PAPV) of major diets and to determine the relationship between dietary PAPV and dairy production traits. Estimation of PAPV of major cattle feeds was based on an in vitro technique, which determined the degree of Ca dissociation from $CaCO_3$. Data on feeds and production traits were collected on 744 multiparous lactating Holstein dairy cows from five different farms. Grains had high PAPV with variable protein sources and by-products. High PAPV feedstuffs had a higher total gas production and lower pH compared to those with low PAPV. Dietary PAPV had a positive correlation with intake of dry matter, NDF, ADF, milk yield and milk solid production but a negative correlation with milk protein and milk fat concentration. Current results indicate that dietary PAPV can be utilized in predicting dairy production traits.

• KSBB Journal
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• 제31권4호
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• pp.246-255
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• 2016

Co-production of 3-hydroxypropionic acid (3-HP) and 1,3-propanediol (1,3-PDO) was suggested as an innovative strategy to overcome several limitations occurring in the single production of 3-HP from glycerol. In this study, two new isolates of Klebsiella pneumoniae, which produce less lipopolysaccharide (LPS) thus considered less pathogenic than K. pneumoniae DSM 2026, were compared and evaluated for their potential for the co-production of 3-HP and 1,3-PDO. The newly isolated strains showed significantly faster sedimentation rate than DSM, which should be beneficial for downstream processing. Analysis of genome sequences of the isolates confirmed the presence of all genes necessary for glycerol assimilation, 1,3-PDO production and biosynthesis of coenzyme $B_{12}$. Co-production yield was highest under anaerobic condition while cell growth was highest under aerobic condition. Both strains showed similarly good performance for the co-production although J2B gave the slightly higher co-production yield of 0.80 mol/mol than GSC021 (0.75 mol/mol). The evaluation of the newly developed strains presented here should be useful in designing similar evaluation experiments for other microorganisms.

• Asian-Australasian Journal of Animal Sciences
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• 제14권11호
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• pp.1516-1519
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• 2001

The data consisted of 369 lactation records for calvings over a sixteen-year period (1972-1987) and included only cows that had normal milk records. The data were analysed using a linear model containing the fixed effects of parity, year of calving and season of calving. The least squares means${\pm}$S.E. were $1,273{\pm}58.4kg$ for milk yield, and for post-partum body weight (kg) at 2, 3 and 4 months after calving were $343.40{\pm}3.96$, $346.10{\pm}4.10$ and $352.54{\pm}4.26$, respectively. With the exception of season of calving, the effects of parity and year of calving were significant (p<0.01) on the performance of the animals. Thus, the mean-milk yields 1162, 1351 and 1350, were similar for pre-, peak- and post rainy seasons, respectively. On the other hand, as parity increased from 1 to 3, milk yield also increased, but thereafter, there was a gradual decline in milk yield. Similarly, post-partum body weight also increased with parity. However, no consistent pattern for year effect was observed which probably was a reflection of the variation in climatic conditions, or forage quality and/or availability. The phenotypic correlations between milk yield and post-partum body weights were negative and small (ranging from -0.01 to -0.08). However, high milk production in cows was associated with longer calving interval. The implications from the phenotypic correlations are suggestive of one or two possibilities. Firstly, selection for increased body weight may actually result in decreased milk yield. Also, a substantial genetic antagonism may exist between milk yield and fertility in the crossbred cows. Therefore, it is important that selection to improve milk production should take into consideration the reproductive performance of the cows.

• 한국미생물·생명공학회지
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• 제19권2호
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• pp.179-185
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• 1991

We examined optimum culture conditions of Rhodopseudomonas sphaeroides B5 for effective utilization of substrate and sunlight for hydrogen production. The optimum concentration range of DL-lactate as electron donor for hydrogen production by resting cells was from 5 to 50mM, and optimun CN ratio (lactate/glutamat) for maintenence of hydrogen production activity by growing cultures was from 5 to 6. Hydrogen production by the cultures of low cell density (0.36mg/ml dry cells) was saturated with 10 Klux light intensity. Under constant illumination of 50Klux which was set up as the average medium value of annual variation of sunlight intensity, hydrogen production with various cell densities in the culture resulted in highest production rate (132${\mu}$l/hr/mg dry cells) up to 0.64mg/ml dry cells. However, the amount of total hydrogen production was saturated with cell density of 2.1mg/ml dry cells. In addition to these, the optimum inner thickness pervious to light of the culture vessel for hydrogen production which was measured under sunlight was 5 cm.

• Journal of Ecology and Environment
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• 제44권4호
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• pp.229-240
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• 2020

Background: Genus Quercus is a successful group that has occupied the largest area of forest around the world including South Korea. The acorns are an important food source for both wild animals and humans. Although the reproductive characteristics of this genus are highly variable, it had been rarely studied in South Korea. Therefore, in Seoraksan and Odaesan National Parks (i) we measured the acorn production of Quercus mongolica, an overwhelmingly dominant species in South Korea, for 3 years (2017-2019), (ii) evaluated the spatial-temporal variation of acorn production, and (iii) analyzed the effects of oak- and site-related variables on the acorn production. Results: The annual acorn production of Q. mongolica increased 36 times from 1.2 g m-2 in 2017 to 43.2 g m-2 in 2018, and decreased to 16.7 g m-2 in 2019, resulting in an annual coefficient of variation of 104%. The coefficient of spatial variation was high and reached a maximum of 142%, and the tree size was the greatest influencing factor. That is, with an increase in tree size, acorn production increased significantly (2018 F = 16.3, p < 0.001; 2019 F = 8.2, p < 0.01). Elevation and slope also significantly affected the production in 2019. However, since elevation and tree size showed a positive correlation (r = 0.517, p < 0.001), the increase in acorn production with increasing elevation was possibly due to the effect of tree size. The acorn production of Odaesan for 3 years was 2.2 times greater than that of Seoraksan. This was presumed that there are more distribution of thick oak trees and more favorable site conditions such as deep soil A-layer depth, high organic matter, and slower slopes. Conclusion: As reported for other species of the genus Quercus, the acorn production of Q. mongolica showed large spatial and annual variations. The temporal variability was presumed to be a weather-influenced masting, while the spatial variability was mainly caused by oak tree size.

• KSBB Journal
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• 제25권3호
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• pp.283-288
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• 2010

We investigated the feasibility of bioethanol production from hydrolysate of brown seaweed Sargassum sagamianum. Prior to bioethanol production using yeasts, six yeast strains were compared and the best ones in terms of the ethanol production levels were selected. Pichia stipitis ATCC 7126, Pichia stipitis ATCC 58784, and Pichia stipitis ATCC 58376 were superior to others in terms of ethanol production. These yeast strains were used for producing bioethanol by the shaking bottle culture and the fermentor culture. Out of approximately 30 g/L reducing sugar, about 3~6 g/L and 4~7 g/L bioethanol were produced in the bottle culture and the fermentor one, respectively. Furthermore, it was observed that around 12~28 g-bioethanol was produced from 1 kilogram of Sargassum sagamianum. Compared with those previously published, these data were almost three to eight times higher in value.

• Asian-Australasian Journal of Animal Sciences
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• 제25권4호
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• pp.496-501
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• 2012

Thirty-five available feeds were fermented in vitro in order to investigate their soluble total organic carbon (TOCs) and methane ($CH_4$) production rate. A fermentation reactor was designed to capture the $CH_4$ gas emitted and to collect liquor from the reactor during in vitro fermentation. The results showed that $CH_4$ production rate greatly varied among feeds with different ingredients. The lowest $CH_4$-producing feeds were corn gluten feed, brewer's grain, and orchard grass among the energy, protein, and forage feed groups, respectively. Significant differences (p<0.05) were found in digestibility, soluble total organic carbon (TOCs), and $CH_4$ emissions among feeds, during 48 h of in vitro fermentation. Digestibility and TOCs was not found to be related due to different fermentation pattern of each but TOCs production was directly proportional to $CH_4$ production (y = 0.0076x, $r^2$ = 0.83). From this in vitro study, TOCs production could be used as an indirect index for estimation of $CH_4$ emission from feed ingredients.

• 한국작물학회:학술대회논문집
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• 한국작물학회 2022년도 추계학술대회
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• pp.106-106
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• 2022

An appropriate amount of nitrogen fertilizer input during rice cultivation is essential for rice growth, quality control, and reduction of greenhouse gases in paddy fields. Therefore, it is necessary to develop a technology that can check whether an appropriate amount of fertilizer is applied in paddy fields. In this study, we tried to derive a method for diagnosing nitrogen fertilization level using spectroscopic diagnosis, physiological analysis, and molecular indicator genes. Nitrogen fertilization treatment was performed in a greenhouse by dividing into five treatment conditions: no fertilization (N0), low fertilization (N0.5), standard fertilization (N1.0), excessive fertilization (N1.5), and double fertilization (N2.0), respectively. Growth characteristics analysis was investigated by nitrogen fertilization conditions and growth stages, and the height of the canopy was analyzed using a laser scanner. Physiological and spectroscopic analyses were performed by analyzing chlorophyll and sugar contents and measuring SPAD and leaf spectrometer on rice leaves. In addition, real-time PCR experiment was performed to check the relative expression levels of several known nitrogen metabolism related genes. These results suggest that spectroscopic techniques can be helpful in diagnosing the level of nitrogen fertilization in rice paddy fields.

• 농업과학연구
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• 제44권1호
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• pp.40-49
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• 2017

Cultural practices for adzuki bean and the distribution of weed species in the south-west regions of Korea were surveyed to provide information on effective weed management. Approximately 27.5% of the farm households were growing adzuki bean in an area larger than 1 ha while the rest grew the crop in an area smaller than 1 ha. Of all adzuki bean growers, 17.1% seeded in early June, 8.6% in mid June, 34.3% in late June, 17.1% in early July, 20.0% in mid July, and 2.9% in late July. The average planting distance was $71.0{\times}29.5cm$. From the 40 surveys in adzuki bean fields, 35 weed species in 17 families were identified. According to the occurrence frequency, the dominant weed species were Digitaria sanguinalis, Acalypha australis, Cyperus amuricus, Echinochloa crus-galli, and Amaranthus nangostanus in decreasing order of dominance. However, based on dry weight, Chenopodium album (34.4%) was the most dominant followed by Acalypha australis (21.9%), Amaranthus nangostanus (19.1%), Digitaria sanguinalis (7.5%), and Portulaca oleracea (6.1%). The exotic weeds found in the field of adzuki were Ipomoea hederacea, Abutilon avicennae, and Celosia argentea. The plant heights of I. hederacea, A. avicennae, and C. argentea were 259 cm, 98 cm, and 76 cm, respectively, while the fresh weights were 850 g, 66 g, and 101 g, respectively. Integrated weed management systems utilizing mechanical, chemical, and biological control techniques need to be developed for effective weed management in adzuki bean production.