• Microbiology and Biotechnology Letters
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• v.43 no.2
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• pp.164-168
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• 2015

Citric acid is produced via submerged fermentation using yeasts. Among eight different strains of yeast, Candida zeylanoides was chosen as the strain for producing citric acid and optimized for various C/N ratios and effects of phosphate or Fe²⁺ ions in a clean carbon source medium (glucose: fructose, 1:1). The yield of citric acid was maximized at a C/N ratio of 40/1, a phosphate addition of 1.0 g/l, and an Fe²⁺ ion concentration of less than 50 mg/l, yielding up to 91 g/L in the broth with 18.5 g/l of isocitric acid in a six-day fermentation period using a pre-treated molasses medium. The yield of batch culture was 0.51 (Y_p/s, g/g) in a 5 L-Jar fermenter.

• Korean Journal of Environmental Agriculture
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• v.13 no.1
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• pp.83-89
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• 1994

The number of colonies often decreased more than would be expected in a dilution from 1:50 to 1:100; however, a lack of agreement between the dilution series and the number of colonies obtained also occurred at higher dilutions. In the experiments with each soil subsample, there was sometimes poor agreement between the number of colonies obtained at the same dilution from the A and B subsamples. However, repeated 1:50 dilutions of soil suspensions of subsamples A and B yielded similar numbers of colonies. In the second experiment series conducted with a second composite soil sample, the number of colonies obtained from each soil subsample decreased following air drying. The results suggest that it was difficult to obtain a uniform distribution of Pythium propagules in the two sugarcane field soils tested. The high number of propagules detected at the 1:50 dilution could have been due to hyphal fragments or connected hyphal swellings that separated during the final mixing or during plating.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.36 no.4
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• pp.300-304
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• 1991

Several experiments were conducted to elucidate a possibility of sweet sorghum, sugar beet and sugar cane as the resources of bio-energy which were collected from Philipine, India, Japan and Gene -bank in Korea. The experiments were carried out in Chinju, Korea from 1986 to 1988. When sweet sorghum cultivars were taken from 70 to 118 days after sowing on May 20, 1988 upto heading stage, the sugar content of stem was 6 to 14% and yielded 4 to 10ton per l0a in terms of the total fresh weight of plant. Sugar beet root contained 9.2 to 19.8% in sugar producting 3,542 to 6. 397kg per l0a. Meanwhile. the sugar content in stem of sugar cane was 15.2 to 16.7% and final growth the late October in this particular region. Particularly, F1 hybrid cultivar(s-l) of sweet sorghum could be harvested twice in a year. The alcohol quantity obtained from the juice of sweet sorghum was 180$\ell$ per l0a and was increased as sowing date was earlier. The results suggested that it would be possible to utilize the sugar crops as bio-energy resources using improved cultural methods and effective fermentation techniques.

• Journal of the Korean Applied Science and Technology
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• v.33 no.4
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• pp.627-633
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• 2016

Sweet sorghum [Sorghum bicolor (L)] is one of the major crops for biofuels such as sugarcane and sugar beet which raw materials rich in saccharide. Sweet sorghum juice was extracted from the stem. It's composed of fermentable sugars such as glucose, fructose and sucrose. Ethanol from the extracted sweet sorghum juice can be easily produced by yeast fermentation process. Sweet sorghum juice is consisted of not only sugars but also various nutrients like nitrogen and phosphate. For commercial production of bioethanol, seed culture is one of the important parts of fermentation, so that optimal culture medium should be selected for the reduction of processing costs. In this study, sweet sorghum juice was estimated as a culture medium for seed culture of cellulosic bioethanol. For the comparison of cultures with various substrates, it used YPD including each 5 g/L yeast extract and peptone, sweet sorghum juice and hydrolyzed Miscanthus was taken part in the culture with 2%, 5% and 10% sugar conditions. Based on media of YPD and sweet sorghum juice, cell-mass concentration was obtained maximum more than $2.5{\times}10^8CFU/mL$ after 24 h of cultivation. Consequently sweet sorghum juice is suitable for the cell culture with more than $1.0{\times}10^8CFU/mL$ after 12 h of cultivation. This can be used as a culture medium for the cellulosic bioethanol industry.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.26 no.1
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• pp.69-89
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• 1981

Stevia (Stevia rebaudiana Bertoni) is a perennial herb widely distributed in the mountainous area of Paraguay. It belongs to the family Compositae and contains 6 to 12 percent stevioside in the leaves. Stevioside is a glucoside having similar sweetening character to surgar and the degree of sweetness is approximately 300 times of sugar. Since Korea does not produce any sugar crops, and the synthetic sweetenings are potentially hazardous for health, it is rather urgent to develop an economical new sweetener. Consequently, the current experiments are conducted to establish cultural practices of stevia, a new sweetening herbs, introduced into Korea in 1973 and the results are summarized as followings: 1. Days from transplanting of cuttings to the flower bud formation of 6 stevia lines were similar among daylengths of 8, 10 and 12 hours, but it was much greater at daylengths of 14 or 24 hour and varietal differences were noticable. All lines were photosensitive, but a line, 77013, was the most sensitive and 77067 and Suweon 2 were less sensitive to daylength. 2. Critical daylength of all lines seemed to be approximately 12 hours. Growth of plants was severely retarded at daylengths less than 12 hours. 3. Cutting were responded to short daylength before rooting. Number of days from transplanting to flower bud formation of 40-day old cuttings in the nursery bed was 20 days and it was delayed as duration of nursery were shorter. 4. Number of days from emergence to flower bud formation was shortest at short day treatment from 20 days after emergence. It was became longer as initiation of short day treatment was earlier or later than 20 days. 5. Plant height, number of branches, and top dry weight of stevia were reduced as cutting date was delayed from March 20 to May 20. The highest yield of dry leaf was obtained at nursery duration of 40-50 days in march 20 cutting, 30-40 days in April 20 cutting, and 30 days in May 20 cutting. 6. An asymptotic relationship was observed between plant population and leaf dry weight. Yield of dry leaf increased rapidly as plant population increased from 5,000 to 10,000 plants/10a with a reduced increasing rate from 10,000 to 20,000 plants/l0a, and levelled off at the plant population higher than 20,000 plants/l0a. 7. Stevia was adaptable in Suweon, Chengju, Mokpo and Jeju and drought was one of the main factors reducing yield of dry leaf. Yield of dry leaf was reduced significantly (approximately 30%) at June 20 transplanting compared to optimum transplanting. 8. Yield of dry leaf was higher in a vinyl house compared to unprotected control at long daylength or natural daylength except at short day treatment at March 20. Higher temperature ill a vinyl house does not have benefital effects at April 20 transplanting. 9. The highest content of stevioside was noted at the upper leaves of the plant but the lowest was measured at the plant parts of 20cm above ground. Leaf dry weight and stevioside yield was mainly contributed by the plant parts of 60 to 120cm above ground but the varietal differences were also significant. 10. Delayed harvest by the time of flower bud formation increased leaf dry weight remarkably. However, there were insignificant changes of yield as harvests were made at any time after flower bud formation. Content of stevioside was highest at the time of flower bud formation and earlier or later harvest than this time was low in its content. The optimum harvesting time determined by leaf dry weight and stevioside content was the periods from flower bud formation to right before flowering that would be the period from September 10 to September 15 in Suweon area. 11. Stevioside and rebaudioside content in the leaves of Stevia varieties were ranged from 5.4% to 14.3% and 1.5% to 8.3% respectively. However, no definit relationships between stevioside and rebaudioside were observed in these particular experiments.

• Korean Journal of Weed Science
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• v.30 no.4
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• pp.330-339
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• 2010

In order to suggest correct direction of researches on Miscanthus spp. which are promising bioenergy crop, authors had reviewed and summarized various literature about botanical taxonomy, morphology and present condition of breeding, cultivation and utilization of miscanthus. Among the genus of Miscanthus which are known 17 species, the most important species are M. sinensis and M. sacchariflorus which origin are East Asia including Korea, and M. x giganteus which is inter-specific hybrid of tetraploid M. sacchariflorus and diploid M. sinensis. Miscanthus is superior to other energy crops in resistance to poor environments including cold, saline and damp soil, nitrogen utilization efficiency, budget of input energy and carbon which are required for producing biomass and output which are stored in biomass. The major species for production of energy and industrial products including construction material in Europe, USA and Canada is M. x giganteus which was introduced from Japan in 1930s. In present, many breeding programs are conducted to supplement demerits of present varieties and to develop "Miscanes" which is hybrid of miscanthus and sugar cane. In Korea, the researches on breeding and cultivation of miscanthus were initiated in 2007 by collecting germplasms, and developed "Goedae-Uksae 1" which is high biomass yield and "mass propagation method of miscanthus" which can improve propagation efficiency in 2009. In order to develop "Korean miscanthus industry" in future, the superior varieties available not only domestic but also foreign market should be developed by new breeding method including molecular markers. Researches on production process of cellulosic bio-ethanol including pre-treatment and saccharification of miscanthus biomass also should be strengthen.

• Korean Journal of Agricultural Science
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• v.35 no.1
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• pp.85-100
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• 2008

The United States Department of Agriculture (USDA) funded collaborative project on The Economic Feasibility Analysis of Crop Cultivation Practice Project in Pirganj and Kurigram Districts in Bangladesh will started during 2008-2012, for 4 years with total project cost of US$ 571,270. The project will be implemented in 6 villages; has 1,097 hectares areas which is divided into 948 hectares of agricultural land, 52 hectares of forest land and 345 hectares of other land, covered 1,059 households equal to 5,305 persons in Pirganj and Kurigram districts The project has proposed to be implemented in joint collaboration by Bangladesh Agricultural Research Council (BARC), Bangladesh Agricultural Research Institute (BARI) and Rangpur Dinajpur Rural Service (RDRS) Bangladesh with full participation of the farmers' groups of respective project site. The specific objectives of the project are: (1) to estimate the productivity of paddy, wheat, maize, tobacco and sugarcane (2) to determine the cost of production and returns to the above mentioned crops (3) to study the interrelationship between inputs and output of the above mentioned crops and (4) to examine the resource utilization patterns at farm level. In this project analysis, the net incremental profit is US$33,028. The expected incremental project benefit and incremented production cost are estimated as US$ 219,959 and US$ 186,931 respectively. The financial decision making criteria would be followed in this crop cultivation practice project. After the project implementation, the expected project benefits are assumed to be continued for 15 years. The benefit cost ratio (B/C) of the project is estimated at 1.077 (table 11) when using discount rate of 10% as an opportunity cost of capital in Bangladesh. FIRR of project is estimated at 26.15% which is bigger than the opportunity cost by more than double. So this project is financially feasible and acceptable. Therefore, this project should be extended to other areas to increase the farm income and economic growth of marginal poor farmers in Bangladesh.