• KSBB Journal
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• v.19 no.3
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• pp.192-199
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• 2004

In this work the production of glutathione (GSH) by yeast Saccharomyces cerevisiae and the monitoring of the process were studied. In shaking culture the production of GSH was high at initial pH value of 4 and at temperature of 30$^{\circ}C$. But when L-cysteine was added to the culture medium at the beginning of the cultivation, the productivity of GSH was low. In case 0,5% (v/v) of L-cysteine, glycine and glutamic acid were introduced to the culture medium in the exponential cell growth phase, high concentration of GSH (about 90 mg/L) was produced in the bioreactor. A fed-batch operation with stepwise glucose feeding strategy allowed to produce 102 mg/L of GSH. The cultivation processes were on-line monitored by a 2-dimensional fluorescence sensor. A few off-line data such as cell growth, cystein concentration, phosphate concentration and GSH productivity could be well correlated to the fluorescence intensity of some combinations of excitation and emission wavelengths.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.20 no.1
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• pp.19-28
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• 2007

Discrete topology optimization processes of structures start from an initial design domain which is described by the topology of constant material densities. During optimization procedures, the structural topology changes in order to satisfy optimization problems in the fixed design domain, and finally, the optimization produces material density distributions with optimal topology. An introduction of initial holes in a design domain presented by Eschenauer et at. has been utilized in order to improve the optimization convergence of boundary-based shape optimization methods by generating finite changes of design variables. This means that an optimal topology depends on an initial topology with respect to topology optimization problems. In this study, it is investigated that various optimal topologies can be yielded under constraints of usable material, when partial solid phases are deposited in an initial design domain and thus initial topology is finitely changed. As a numerical application, structural topology optimization of a simple MBB-Beam is carried out, applying partial circular solid phases with varying sizes to an initial design domain.

• Korean Journal of Poultry Science
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• v.47 no.4
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• pp.237-245
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• 2020

This study investigated the effects of breed, laying age, and egg storage period on hatching performance. Eggs were collected from early laying period (27 to 29 weeks old) and late laying period (50 to 52 weeks old) in Hwanggalsaek Jaeraejong, Korean Rhode Island Red, and Korean White Leghorn chicken breeds. Eggs laid for each period were stored for 3, 7 and 14 days and then hatched. Fertility, hatchability, and embryonic mortality were observed to determine the hatching performance. The results showed that hatching performance was affected by breed, laying age, and egg storage period with independently or interactively. The Korean Rhode Island Red breed had the lowest hatching performance. Hatchability and early embryonic mortality rate increased in early laying period eggs compared to the late laying period, but the late embryonic mortality rate increased in late laying period eggs. Additionally, hatching performance decreased as the egg storage period increased. Using breed-specific hatching management techniques, avoiding late laying period eggs, and shortening the egg storage period to seven days after laying may improve the hatching performance.

• Proceedings of the Korean Society of Fisheries Technology Conference
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• 2003.05a
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• pp.191-192
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• 2003

수산양식에 있어서 초기 치자어의 영양은 치자어의 생존 및 성장에 많은 영향을 미친다. 이와 같은 영양에는 주로 DHA와 EPA 등으로 많은 연구자들은 그 초점을 두고 있다. 그러나, 실제 어류에 있어서 부화 직후의 영양소 섭식 능력은 많은 종에 있어서 미지수로 종묘생산시 초기 감모기를 겪고 있으며 이 시기를 부화 후 first feeding 단계의 5∼10일로 잡고 있다. 그러나 이 초기 감모기를 지난 자치어는 rotifer와 Artemia 같은 살아있는 먹이생물을 이용하기에 충분하기 때문에 생존율에는 큰 영향이 없는 것으로 보고되어지고 있다. (중략)

• Feed Journal
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• v.3 no.7 s.23
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• pp.72-77
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• 2005

앞으로는 사료의 생산과 판매가 분리되어 갈 수 있다. 그 중심에는 단연 OEM사료가 선도적인 역할을 할 것이다. 초창기 OEM사료는 시대적인 상황과 필요성이 맞물려 등장했지만, 오늘날까지 성장과 발전을 멈추지 않고 있다. 초기에는 가격이 저렴하다는 인식이 많았지만, OEM사료의 실제 근본 취지는 농장에 맞는 맞춤사료를 설계하여, 최소의 비용으로 최대의 생산성을 올리는데 의의가 있다고 생각된다.

• Journal of the korean Society of Automotive Engineers
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• v.19 no.1
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• pp.61-73
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• 1997

결론적으로 자동차 산업에서 생산기술의 경쟁력 확보란 제품의 품질과 원가측면에서의 경쟁력을 확보해야 함을 의미한다. 원가 경쟁력을 확보하기 위해서는 신제품개발 초기단계에서 부터 경쟁력있는 Target을 설정하고, 전분야의 철저한 SE(동시공학)의 실현을 통해 달성해야 할 것이다.

• KSBB Journal
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• v.8 no.5
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• pp.457-464
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• 1993

In this study, an attempt was made to investigate optimum cell growth and products by Bacillus amyloliquefaciens 23350 in batch culture by varing carbon soures. Maximum dry cell density increased with the increase of initial glucose concentration. Maximum dry cell density was obtained with the highest value of 5.2g/l at 30g/l of initial glucose concentration. By adding acetic acid at 20g/l of initial glucose concentration, the cell growth rate decreased with the increase of initial acetic acid concentration. Among the various carbon sources, maximum $\alpha$-amylase production was obtained with 225unit/ml at 10g/1 of initial glucose concentration. Optimum production of $\alpha$-amylase was obtained with 376unit/ml at 2g/l of initial acetic acid concentration and 20g/l of initial glucose concentration. By 10g/1 of initial glucose concentration, both good maximum specific cell growth rate and maximum $\alpha$-amylase production rate were obtained. In view of the results studied optimum production and specific production rate of $\alpha$-amylase, acetic acid was initially added 2~4g/l with 20g/1 of initial glucose concentration in batch culture.

• Korean Journal of Plant Resources
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• v.26 no.4
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• pp.503-510
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• 2013

This study was conducted to determine the optimum intensity of root pruning and the initial seedling size of 1-year-old Quercus serrata for producing 2-year-old healthy seedlings. Large( > 26 cm hight) and small size ( < 24 cm hight) seedlings were pruned their root by the length of 5, 10, and 15cm and then transplanted on nursery. Stem height, root-collar diameter(RCD), height to RCD ratio(H/D ratio), shoot dry weight(DW) and root development were measured during first growing season after transplanting. Seedling size and pruning intensity influenced on shoot growth such as height, RCD, H/D ratio and DW after transplanting. In addition, the development of lateral roots such as number, length, DW and diameter were affected by the seedling size. Taproot pruned by 15cm was shown excellent above-ground growth in large seedling group, but pruned by 10 and 15cm showed respectively better shoot growth in small seedling group. Large seedlings increased their above-ground growth, taproot regrowth, and number of lateral roots more than those of the small seedlings. But the length and DW of lateral roots were increased in the small seedlings. In conclusion, in order to produce high quality 2-year-old seedlings, it is important to produce large size of Q. serrata seedlings. Also root pruning length of 1-year-old Q. serrata was reasonable on 15 cm in taller than 26 cm or 10cm in less than the height.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.2
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• pp.156-159
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• 2001

The experiment was carried out to investigate the productivity of freshwater rotifer, Brachionus calyciflorus and marine rotifer, B. rotundiformis at various temperatures, initial inoculation and pH in a 5 L semi-continuous high density culture. Rotifers were fed by commercial condensed freshwater Chlorella. When pH was not controlled, average daily productions of freshwater and marine rotifers increased with temperature. The highest production, $44\times10^6$ rotifers, was achieved of B. calyciflorus at $32^{\circ}C$ and the possible production lasting period of B. calyciflorus was shorter than that of B. rotundiformis. Under the adjustment of pH at 7, the possible production lasting periods of B. calyciflorus and B. rotundiformis inoculated with 5,000 inds./mL were longer than those of rotifers inoculated with 10,000 inds./mL, and the daily production rate of the former was higher than that of the latter. The results from this study indicated that optimum density of the initial inoculation for the cultivation of B. calyciflorus and B. rotundiformis was 5,000 inds,/mL under the controlled conditions of pH 7 and at $32^{\circ}C$ in a semi-continuous high density culture, in terms of production rate and food cost aspects.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.5
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• pp.834-841
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• 1997

A lactic acid bacteria which showed antimicrobial activity was isolated from dairy products and identified as Lactobacillus sp. according to the morphological, physiological and biochemical properties, which was named Lactobacillus sp. SH 7311. The bacteriocin of Lactobacillus sp. GM 7311 showed a broad range of inhibitory spectrum against some gram positive and negative bacteria. Especially, Proteus mirabilis was highly sensitive to bacteriocin and used as indicator strain for further investigation. The optimal condition for the production of bacteriocin was showed on MRS broth at $37^{\circ}C$ and pM 6.0. Bacteriocin production of this strain cultured under optimal condition was increased late logarithmic phase to early stationary phase. This bacteriocin was fully active at the pH range $2.0\~5.0$, also was stable at $100^{\circ}C$ for 60 min. at pH 5.0, But about $40\%$ of bacteriocin activity was diminished by the treatment of acetone, ethanol, iso-butanol and ethyl ether during 2 hours at $4^{\circ}C$.