• 한국분말야금학회:학술대회논문집
• /
• 한국분말야금학회 2006년도 Extended Abstracts of 2006 POWDER METALLURGY World Congress Part 1
• /
• pp.596-596
• /
• 2006

• Journal of Microbiology and Biotechnology
• /
• 제2권3호
• /
• pp.197-203
• /
• 1992

Studies of the pretreatment of chitin and its subsequent hydrolysis by Aspergillus carneus chitinase are reported. Ball milling was found to be the most effective way among the pretreatment methods tested. Data are presented describing the effect of enzyme and substrate concentrations on the rate and extent of the hydrolysis process. It was found that the successive addition of enzyme improved the saccharification yield. Significant product inhibition of the chitinase was observed when N-acetylglucosamine concentration was 3.6％ or higher. Adsorption of enzymes to the substrate occurred during a 24 hr hydrolysis period. An initial rapid and extensive adsorption occurred, followed by gradual desorption which increased during the time of reaction. Intermediate removal of the hydrolyzate and continuation of the hydrolysis by adsorbed enzyme on the residual chitin was also investigated. A total of 75.4 g/l reducing sugars, corresponding to 69.2％ saccharificaton yield (as N-acetylglucosamine) was obtained. In addition an increase in the amount of recoverable enzymes was observed under these conditions. Evidence presented here suggests that the technique, whereby the free enzymes in the recovered hydrolyzate are re-adsorbed onto the new substrate, may provide a means of recirculating the dissolved enzymes.

• KSBB Journal
• /
• 제22권1호
• /
• pp.43-47
• /
• 2007

신문지와 같은 폐지의 가수분해에 미치는 계면활성제의 영향을 조사하였다. 전처리 공정에 적합한 계면활성제는 사용한 9종의 비이온 계면활성제 중 NP 계열 계면활성제가 가장 좋은 전처리 효과를 나타내었다. NP-20을 사용하여 전처리 공정을 최적화한 결과 계면활성제 농도, 교반속도, 전처리 온도와 시간이 0.5%, 100 rpm, 30$^{\circ}C$와 1시간일 때 최적조건이었다. 당화율을 최대화하기 위하여 기질을 NP-20으로 전처리하고 전처리된 기질을 TW-80을 첨가하여 가수분해하였다. 계면활성제를 사용하여 전처리된 기질을 계면활성제를 첨가하여 가수분해하면 가수분해에서 계면활성제의 효과가 거의 없었다. 그래서 가수분해 공정에서만 계면활성제를 사용하여 효소와 계면활성제의 첨가 순서에 따른 당화율을 조사하였다. 조사결과 기질에 효소를 넣고 난 후 계면활성제의 첨가시기가 늦을수록 당화율이 낮아지는 경향을 나타내었다.

• KSBB Journal
• /
• 제29권3호
• /
• pp.193-198
• /
• 2014

Pretreatment of wastepaper using aqueous glycerol under high pressure was studied to enhance the enzymatic hydrolysis. The pretreatment was conducted over a wide range of conditions including temperatures of $150{\sim}170^{\circ}C$, sulfuric acid concentrations of 0.5~1.5%, and reaction times of 30~90 minutes. After the effect of glycerol concentration on the pretreatment performance was investigated, 70% glycerol was selected. As glycerol concentration was increased, higher digestibility was achieved due to higher lignin removal. The optimum condition was found to be around $160^{\circ}C$, 1%, and 60 minutes. At this condition, 60% and 35% of hemicellulose and lignin, respectively, were removed, while only 5% of cellulose was lost. The enzymatic digestibility was 76%, meaning that 73% of the glucan present in the initial substrate was recovered as glucose after enzymatic hydrolysis. Also, it was found that the temperature and acid concentration than the reaction time were more strongly related to the compositional removals and enzymatic digestibility.

• KSBB Journal
• /
• 제30권6호
• /
• pp.332-338
• /
• 2015

The objective of this study was designed to determine the possibility of bioethanol production from wasted medium density fiberboard (wMDF). We were investigated the enzymatic saccharification characteristics using the enzyme (Cellic CTec3) after pretreatment with sodium chlorite. According to the component analysis results, the lignin contents before and after the pretreatment of wMDF (milling using sieve size of $1,000{\mu}m$) was significantly reduced from 31.13% to 4.11%. Therefore, delignification ratio of pretreated wMDF was found to be up to about 87-89% depending on the sieve size. And we were tested to compare the saccharification ratio according to the sieve size of wMDF ($1,000{\mu}m$, $200{\mu}m$), but it was no significance depending on the sieve size. When enzyme dosage was 5% based on the substrate concentration, enzymatic saccharification ratio was obtained up to 70% by maintaining at $50^{\circ}C$ for 72 hours. We could made the substrate concentration of pretreated wMDF ($1,000{\mu}m$) up to 12% and then enzymatic saccharification ratio was 76.8%, also contents of glucose and xylose were analyzed to 77,750 and 14,637 mg/L, respectively.

• 한국전기전자재료학회논문지
• /
• 제23권5호
• /
• pp.374-378
• /
• 2010

The effects of $O_2$ plasma pretreatment on the properties of Ga-doped ZnO films on polyimide substrate were studied. GZO films were fabricated by RF magnetron sputtering process. To improve surface energy and adhesion between the polyimide substrate and the GZO film, $O_2$ plasma pretreatment process was used prior to GZO sputtering. As the RF power and the treatment time increased, the crystallinity increased and the contact angle decreased significantly. When the RF power was 100 W and the treatment time was 120 sec, the resistivity of GZO films on the polyimide substrate was $1.90{\times}10^{-3}{\Omega}-cm$.

• 한국재료학회지
• /
• 제20권4호
• /
• pp.175-180
• /
• 2010

Transparent conducting oxide (TCO) films are widely used for optoelectronic applications. Among TCO materials, zinc oxide (ZnO) has been studied extensively for its high optical transmission and electrical conduction. In this study, the effects of $O_2$ plasma pretreatment on the properties of Ga-doped ZnO films (GZO) on polyethylene naphthalate (PEN) substrate were studied. The $O_2$ plasma pretreatment process was used instead of conventional oxide buffer layers. The $O_2$ plasma treatment process has several merits compared with the oxide buffer layer treatment, especially on a mass production scale. In this process, an additional sputtering system for oxide composition is not needed and the plasma treatment process is easily adopted as an in-line process. GZO films were fabricated by RF magnetron sputtering process. To improve surface energy and adhesion between the PEN substrate and the GZO film, the $O_2$ plasma pre-treatment process was used prior to GZO sputtering. As the RF power and the treatment time increased, the contact angle decreased and the RMS surface roughness increased significantly. It is believed that the surface energy and adhesive force of the polymer surfaces increased with the $O_2$ plasma treatment and that the crystallinity and grain size of the GZO films increased. When the RF power was 100W and the treatment time was 120 sec in the $O_2$ plasma pretreatment process, the resistivity of the GZO films on the PEN substrate was $1.05\;{\times}\;10^{-3}{\Omega}-cm$, which is an appropriate range for most optoelectronic applications.

• 한국정보디스플레이학회:학술대회논문집
• /
• 한국정보디스플레이학회 2008년도 International Meeting on Information Display
• /
• pp.617-619
• /
• 2008

Inorganic-organic hybrid multilayers were formed on the plastic substrate to enhance the barrier properties of substrate to water vapor and oxygen transport. Plasma pretreatment of substrate with $Ar/O_2$ lead to adhesion improvement and the densification of inorganic layer on the substrates. Combination of $SiO_xN_y$ layer and silanenanoclay composite layer offered quite good barrier properties (WVTR and OTR) to PES substrate.

• 한국결정성장학회지
• /
• 제23권6호
• /
• pp.296-301
• /
• 2013

Carbon coils could be synthesized using $C_2H_2/H_2$ as source gases and $SF_6$ as an incorporated additive gas under the thermal chemical vapor deposition system. A 304-type stainless steel was used as a substrate with nickel powders as the catalyst. The surface of the substrate was pretreated using a sand paper or a mechanical drill to enhance the production yield of the carbon coils. The characteristics of the deposited carbon nanomaterials on the substrates were investigated according to the surface state on the stainless steel substrate. The protrusion induced by the grooves on the substrate surface could enhance the formation of the carbon nanomaterials having the coils geometries. The cause for the enhancement of the carbon coils formation by the grooves was suggested and discussed with the surface energies for the interaction between as-growing carbon elements. Finally, we could obtain the massive production yield of the carbon coils by the surface pretreatment using SiC sand papers on the several tens grooved stainless steel substrate.

• 상하수도학회지
• /
• 제23권6호
• /
• pp.811-823
• /
• 2009

Seawater desalination process using a reverse osmosis (RO) membrane has been considered as one of the most promising technologies in solving the water scarcity problems in many arid regions around the world. To protect RO membrane in the process, a thorough understanding of the pretreatment process is particularly needed. Seawater organic matters (SWOMs) may form a gel layer on the membrane surface, which will increase a concentration polarization. As the SWOMs can be utilized as a substrate, membrane biofouling will be progressed on the RO membrane surface, resulting in the flux decline and increase of trans-membrane pressure drop and salt passage. In the middle of disinfection, an optimal chlorine dosage and neutralizer (sodium bisulfite, SBS) should be practiced to prevent oxidizing the surface of RO membranes. Additional fundamental research including novel non-susceptible biofouling membranes would be necessary to provide a guide line for the proper pretreatment process.