• Korean Chemical Engineering Research
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• 제46권5호
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• pp.858-862
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• 2008

분리 당화발효(Separate Hydrolysis and Fermentation, SHF)는 당화와 발효공정을 따로 수행하는 방법으로 최종 생성물인 글루코오스에 의해 억제 영향을 받기 때문에 반응에 진행됨에 따라 축적된 글루코오스의 농도가 높아지면 반응이 종결되는 단점이 있다. 이를 극복하기 위해 효소의 양을 늘리는 방법이 있지만, 효소의 생산비용이 비싸기 때문에 경제적인 방법이 될 수 없다. 이러한 분리 당화발효 공정의 단점을 극복하기 위해서 동시당화발효 공정(Simultaneous Saccharification and Fermentation, SSF)은 하나의 반응기에서 당화와 발효를 동시에 수행한다. 동시당화발효 공정에서는 당화과정에서 글루코오스가 생성되자마자 효모가 발효과정을 통해 글루코오스를 바로 제거하기 때문에 반응기내에서 당의 축적을 최소화할 수 있다. 따라서 동시당화발효 공정은 최종 생성물의 억제 작용을 방지할 수 있고, 효소의 가수분해 반응을 향상시킬 수 있다. 본 연구에서는 동시당화발효에서 에탄올의 수율에 관여하는 조건들(pH, 반응온도, 효소 투입량, 반응시간)의 최적 조건을 찾는 연구를 수행하였다. 기질로는 감자전분을 사용하였고, 효소는 glucoamylase, 균주는 Saccharomyces cerevisiae가 각각 사용되었다. 동시당화발효의 최적의 조건은 pH 4, 온도 38로 나타났다. 최적의 조건으로 감자전분을 동시당화발효하였을 때 반응 18시간 후에 에탄올은 최대 수율 86%에 도달하였다.

• Journal of Microbiology and Biotechnology
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• 제21권7호
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• pp.703-710
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• 2011

Enzymatic saccharification of corn stover using Phanerochaete chrysosporium and Gloeophyllum trabeum and subsequent fermentation of the saccharification products to ethanol by Saccharomyces cerevisiae and Escherichia coli K011 were achieved. Prior to simultaneous saccharification and fermentation (SSF) for ethanol production, solid-state fermentation was performed for four days on ground corn stover using either P. chrysosporium or G. trabeum to induce in situ cellulase production. During SSF with S. cerevisiae or E. coli, ethanol production was the highest on day 4 for all samples. For corn stover treated with P. chrysosporium, the conversion to ethanol was 2.29 g/100 g corn stover with S. cerevisiae as the fermenting organism, whereas for the sample inoculated with E. coli K011, the ethanol production was 4.14 g/100 g corn stover. Corn stover treated with G. trabeum showed a conversion 1.90 and 4.79 g/100 g corn stover with S. cerevisiae and E. coli K011 as the fermenting organisms, respectively. Other fermentation co-products, such as acetic acid and lactic acid, were also monitored. Acetic acid production ranged between 0.45 and 0.78 g/100 g corn stover, while no lactic acid production was detected throughout the 5 days of SSF. The results of our experiment suggest that it is possible to perform SSF of corn stover using P. chrysosporium, G. trabeum, S. cerevisiae and E. coli K011 for the production of fuel ethanol.

• Asian-Australasian Journal of Animal Sciences
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• 제32권3호
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• pp.357-365
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• 2019

Objective: The experiment was conducted to evaluate the effects of four fungal pretreatments on the nutritional value of Camellia seed residues, and to evaluate the feeding value of pretreated Camellia seed residues for ruminants. Methods: Camellia seed residues were firstly fermented by four lignin degrading fungi, namely, Phanerochaete chrysosporium (P. chrysosporium)-30942, Trichoderma koningiopsis (T. koningiopsis)-2660, Trichoderma aspellum (T. aspellum)-2527, or T. aspellum-2627, under solid-state fermentation (SSF) conditions at six different incubation times. The nutritional value of each fermented Camellia seed residues was then analyzed. The fermentation profiles, organic matter degradability and metabolizable energy of each pre-treated Camellia seed residue were further evaluated using an in vitro rumen fermentation system. Results: After 5 days of fermentation, P. chrysosporium-30942 had higher degradation of lignin (20.51%), consumed less hemicellulose (4.02%), and the SSF efficiency reached 83.43%. T. koningiopsis-2660 degraded more lignin (21.54%) and consumed less cellulose (20.94%) and hemicellulose (2.51%), the SSF efficiency reached 127.93%. The maximum SSF efficiency was 58.18% for T. aspellum-2527 and 47.61% for T. aspellum-2627, appeared at 30 and 15 days respectively. All the fungal pretreatments significantly improved the crude protein content (p<0.05). The Camellia seed residues pretreated for 5 days were found to possess significantly increased organic matter degradability, volatile fatty acid production and metabolizable energy (p<0.05) after the treatment of either P. chrysosporium-30942, T. koningiopsis-2660 or T. aspellum-2527. The fungal pretreatments did not significantly change the rumen fermentation pattern of Camellia seed residues, with an unchanged ratio of acetate to propionate. Conclusion: The fungi showed excellent potential for the solid-state bioconversion of Camellia seed residues into digestible ruminant energy feed, and their shorter lignin degradation characteristics could reduce loss of the other available carbohydrates during SSF.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 1997년도 춘계학술대회 논문집
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• pp.597-601
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• 1997

The technology of Semi-Solid Forging(SSF) has been actively developed to fabricate near-net shape products using light and hardly formable materials. Generally, the SSF process is composed of slug heating,forming,compression holding and ejecting step. After forming step in SSF, the slug is comperssed during a certain holding time in order to be completely filled in the die cavity and be accelerated in solidification rate. This paper presents the analysis of temperature,solid fraction and shrinkage at compression holding step for a cylindrical slug,then predicts the solidification time to obtain the final shaped part. Enthalpy-based finite element analysis is performed to solve the heat transfer problem considering phase change in solidification.

• KSBB Journal
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• 제27권2호
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• pp.86-90
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• 2012

Ethanol fermentations were carried out using simultaneous saccharification and fermentation (SSF) and separated hydrolysis and fermentation (SHF) processes with monosaccharides from seaweed, Saccharina japonica (sea tangle, Dasima) as the biomass. The pretreatment was carried out by thermal acid hydrolysis with $H_2SO_4$ or HCl. Optimal pretreatment condition was determined at 10% (w/v) seaweed slurry with 37.5 mM $H_2SO_4$ at $121^{\circ}C$ for 60 min. To increase the yield of saccharfication, isolated marine bacteria Bacillus sp. JS-1 was used and 48 g/L of reducing sugar were produced. Ethanol fermentation was performed using SSF and SHF process with Pachysolen tannophilus KCTC 7937. The ethanol concentration was 6.5 g/L by SSF and 6.0 g/L by SHF.

• 한국미생물·생명공학회지
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• 제11권3호
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• pp.181-185
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• 1983

증자하지 않은 Cassava의 생전분의 ethanol 발효생산을 위하여 Aspergilius shirousami 가생산하는 당화효소를 이용하여 단순당화 및 동시당화 발효를 하였다. Cassava 생전분의 당화률은 증자한 것에 비해 30% 정도였으며 10배의 효소를 가하여도 60%밖에 안되었으나. 동시당화-발효에서는 당화율이 크게 증가하여 ethanol 생성량이 증자한 전분에 비해 90% 이상이 되었다.

• Journal of Microbiology and Biotechnology
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• 제9권3호
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• pp.297-302
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• 1999

Simultaneous saccharification and fermentation (SSF) experiments were carried out with a lignocellulosic biomass. The effects of temperature on enzymatic saccharification and the ethanol fermentation were also investigated. The batch SSF process gave a final ethanol concentration of 10.44 g/l and equivalent glucose yield of 0.55 g/g, which was increased by 67％ or higher over the saccharification at 42℃. The optimal operating condition was found to vary in several parameters, such as the transmembrane pressure, permeation rate, and separation coefficient, related to the SSF combined with membrane system (semi-batch system). When the fermentation was operated in a semi-batch mode, the efficiency of the enzymes and yeast lasted three times longer than in a batch mode.

• 한국정밀공학회지
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• 제14권10호
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• pp.102-108
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• 1997

The technology of Semi-Solid Forging (SSF) has been actively developed to fabricate near-net- shape products using light and hardly formable materials. Generally, the SSF process is composed of slug heating, forming, compression holding and ejecting step. After forming step in SSF, the slug is compressed during a certain holding time in order to be completely filled in the die cavity and be accelerated in solidification rate. This paper presents the analysis of temperature, solid fraction and shrinkage at compression holding step for a cylindrical slug, then predicts the solidification time to obtain the final shaped part. Enthalpy-based finite element analysis is performed to solve the heat transfer problem considering phase change in solidification.

• 미생물학회지
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• 제26권3호
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• pp.278-282
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• 1988

볏짚을 이용하여 acetone-butanol을 생산하기 위해 전처리한 볏짚을 C. acetobutylicum KCTC 1037(ATCC 4259)과 Trichoderma viride로부터 얻은 섬유소 분해효소를 이용하여 동시당화 발효법 (SSF)으로 발효하였다. Ball-mill로 처리한 볏짚을 SSF로 발효한 결과 acetate와 butyrate안을 생산하였으나, alkali로 전처리한 기질은 230 mM 이상의 solvent를 생산하였다. 이와 같은 발효의 차이는 볏짚에는 alkali 처리로 분해되는 물질이 있으며, 이 물질이 solvent 생산을 저해하기 때문인 것으로 판단된다. 이러한 solvent 생산 저해물질은 물이나 유기용매에 불용성으로 lignin 유도체 혹은 잔류농약으로 추측된다.

• Journal of Information Processing Systems
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• 제15권6호
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• pp.1503-1516
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• 2019

In this paper, to improve the accuracy of long sentence similarity calculation, we proposed a sentence similarity calculation method based on a system similarity function. The algorithm uses word2vector as the system elements to calculate the sentence similarity. The higher accuracy of our algorithm is derived from two characteristics: one is the negative effect of penalty item, and the other is that sentence similar function (SSF) based on word2vector similar elements doesn't satisfy the exchange rule. In later studies, we found the time complexity of our algorithm depends on the process of calculating similar elements, so we build an index of potentially similar elements when training the word vector process. Finally, the experimental results show that our algorithm has higher accuracy than the word mover's distance (WMD), and has the least query time of three calculation methods of SSF.