• Korean Journal of Fisheries and Aquatic Sciences
• /
• v.32 no.1
• /
• pp.83-87
• /
• 1999

Immobilization of amyloglucosidase (AMG) with chitosan microbead and its possible applications were evaluated. The diameter of chitosan inicrobead was about 1.2 mm and the optimum enzyme concentration for immobilization was 6 mg/ml. The relative activity of the immobilized enzyme was $97.8\%$ at pH 4.2 and $55^{\circ}C$ and the optimum condition for the immobilized enwme was the same to that of free enzyme. In case of temperature above $30^{\circ}C$, the activity of the immobilized enzyme was a little higher than that of free enzyme. The enzyme activities of both free and immobilized were stable for 6 months when stored at $35^{\circ}C$. The optimum temperatures of both enzymes for saccharification of the dextrinized starch were $55^{\circ}C$ while the relative activity of the immobilized enzlme was $62.6\%$.

• Journal of Energy Engineering
• /
• v.19 no.4
• /
• pp.240-245
• /
• 2010

In this study, characteristics of wood pellet gasification was studied using a Two Stage Gasifier which is consisted of pyrolysis reactor and ultra high temperature reformer. The average yields of $H_2$, $CH_4$, CO, $CO_2$ were 16.7, 11.3, 37.2, 26.6 L/mim, conversion rate from biomass to gas was 65% in pyrolysis reactor and gas yields in reformer were 55.4, 0.8, 120.8, 56.8 L/mim, respectively. The hydrogen flow rate from reformer is obtained 360.1 L/hr. The most of $CH_4$ was decomposed from 12.3 to 0.3 vol.% while $H_2$ is from 18.2 to 23.7 vol.% in reformer by methane dry reforming, Boudouard reaction, oxidation and/or steam reforming. The amount of $H_2O$ generated by hydration reaction from reformer was 1111.8 g, its accelerated conversion of $CH_4$ to other products. The conversion rate from $CH_4$ to other Compounds was 97.2%. Cold gas efficiency was 53.2%.

• Proceedings of the KWS Conference
• /
• 2009.11a
• /
• pp.27-27
• /
• 2009

드라이브 샤프트는 일반적으로 엔진에서 발생된 회전력을 바퀴에 직접 전달하는 동시에 조향기능을 수행하는 자동차 부품이다. 최근에 경량화를 통한 에너지 절감을 위하여 기존 스틸소재를 알루미늄으로 대체하는 방안에 대한 연구가 집중되고 있다. 그러나 알루미늄 단일소재로 드라이브 샤프트를 제조하는 것은 비경제적이며 또한 기 개발된 자동차 부품들과의 연결을 고려하여 알루미늄 튜브와 스틸 요크의 이종금속 접합기술이 요구된다. 전자기 펄스용접은 전자기력을 이용하여 용접대상물을 고속으로 충돌시켜 용접하는 기술로서 열 발생이 적어 재료의 특성차로 인한 결함 및 변형이 발생하지 않아, 이종금속간 고품질 용접이 가능하며, 전자기 펄스 용접부의 품질과 밀접한 관계를 갖는 공정변수 경우 모재와 접합재의 재질 따라 적정 공정변수 범위가 변화되므로 공정에 따른 데이터의 축적은 대단히 중요하다. 전자기 펄스 용접을 이용한 이종금속 접합시 접합부 품질에 영향을 미치는 공정변수는 충전전압, 모재와 접합재 사이의 간격 및 접합재의 직경과 두께의 비(D/T비)로서 보고되었으며, Al/Steel 이종 금속 접합시 이들 공정변수가 접합부에 미치는 영향 및 최적의 공정변수 도출을 위한 연구는 시도되지 않았다. 따라서 본 연구는 전자기 펄스 용접기술을 이용한 Al/Steel 이종금속 접합 실험을 통하여 전자기 펄스용접의 적정성과 최적의 충전전압, 모재와 접합재 사이의 간격, D/T비를 도출하고자 한다. 전자기 펄스 용접 장치는 한국생산기술연구원과 웰메이트(주)에서 공동으로 개발한 $120{\mu}F$의 캐패시터 6개로 구성된 'W-MPW36'을 사용하였으며 이 장치의 최대충전전압과 최대접합용량은 각각 10kV, 36kJ이다. 접합재는 전기 전도율의 높은 Al 1070 파이프를 사용하였으며 모재는 기존 스틸 요크재인 SM45C 환봉을 사용하였다. 기보고된 연구를 통하여 코일과 접합재 사이의 간격이 좁을수록 높은 전자기력이 접합재에 작용하는 것을 확인하였으나 코일내 접합재와 모재 삽입 편의를 위하여 1mm로 설정하였다. 접합부의 품질 평가를 위하여 수압시험을 실시하였으며, 시험 후 접합부 단면을 주사전자현미경(SEM)을 이용하여 관찰하였다.

• Journal of Life Science
• /
• v.30 no.2
• /
• pp.162-168
• /
• 2020

Because of a continual reduction in its domestic market share, the quality of the Makgeolli, a Korean traditional liquor, needs to be upgraded. Among the several options for quality improvement, sufficient organoleptic expression of flavor is very important. We analyzed production changes of isoamyl acetate, which has a banana smell, based on fermentation temperature and sugar content through the cultivation of S. cerevisiae 98-5 KCCM 11396P using generally polished rice. The banana flavor of that fermentation mash was organoleptically high at 20℃, but a larger amount of isoamyl acetate was obtained with a higher sugar content at 10℃, based on analysis by GC-MS. Consequently, sufficient production of banana flavor from isoamyl acetate was based on the concentration of isoamyl alcohol as a substrate compound of isoamyl acetate, and the production depended highly on the maintenance of heat stability, since it is unstable in temperature and the minimized inhibition of alcohol acetyl transferase by unsaturated fatty acids. We also found that production of the flavor component required the addition of sugar and a slightly higher temperature of 20~25℃ at the beginning stage of fermentation, with additional mash fermentation and a gradual decrease in temperature to 10~15℃.

• Korean Journal of Food Science and Technology
• /
• v.32 no.3
• /
• pp.564-569
• /
• 2000

An enzyme-linked immunosorbent assay(ELISA) was developed for the detection of milk proteins in processed foods. The ${\alpha}_{s1}-casein({\alpha}_{s1}-CN)$, a heat stable major milk protein, was immunized into rabbits to produce specific antibodies. When competitive indirect ELISA(ciELISA) using $anti-{\alpha}_{s1}-CN$ antibodies was established, its detection limit was $0.1\;{\mu}g/mL$. The reactivities of the specific antibodies toward ${\alpha}_{s1}-CN$, skim milk, ${\beta}-CN$ and whey protein isolate(WPI) were 100, 37, 0.14 and 0.04%, respectively, as determined by ciELISA. However $anti-{\alpha}_{s1}-CN$ antibodies did not have any reactivity to other milk proteins such as ${\beta}-lactoglobulin,\;{\alpha}-lactalbumin$, bovine serum albumin, and isolated soy protein. When sandwich ELISA was established, its detection limit was $0.01\;{\mu}g/mL$ which was 10 times more sensitive than that of ciELISA. In the spike test which was performed by adding 1-10% of whole CN to market milk, mean assay recovery as determined by sandwich ELISA was 94.8%(CV, 8.2%). Food stuffs and dairy products were assayed by sandwich ELISA to show 29, 0.13, 0.25, and 6.9% of whole CN in skim milk powder, WPI, semi-solid yoghurt, and processed cheese, respectively.

• Korean Journal of Food Science and Technology
• /
• v.3 no.3
• /
• pp.172-177
• /
• 1971

The amount of the milk clotting enzyme which is produced by Dothiorella ribis in wheat bran was 950 Soxhlet units per gram of wheat bran. The milk clotting activity of this enzyme was increased by the elevation of clotting temperature and by the increase of the addition of $CaCl_2$ to milk. It was also increased when the pH of milk was lower than that of the fresh milk. When milk was diluted by distilled water, the milk clotting activity of the enzyme was decreased. And its milk clotting activity was good when milk was pasteurized at low temperature. The enzyme of Dothiorella ribis has larger proteolytic activity per Soxhlet unit than that of the milk clotting enzyme of Mucor pusillus Lindt. This enzyme was rather stable between pH 6 and pH 8 when it was conditioned for ten minutes. The heat stability of enzyme was tested by treating it under the condition for $10{\sim}60$ minutes. And the enzyme was stable under the temperature of $45^{\circ}C$. Also the recovery of protein as a form of curd was 76.2 percent to the total protein content of milk.

• Korean Chemical Engineering Research
• /
• v.51 no.4
• /
• pp.506-512
• /
• 2013

Biomass and low-grade coals are known to be better potential sources of energy compared to crude oil and natural gas since these materials are readily available and found to have large reserves, respectively. Gasification of these carbonaceous materials produced syngas for chemical synthesis and power generation. Woodchip, sawdust and lignite were gasified with steam in a thermobalance reactor under atmospheric pressure in order to evaluate their kinetic rate information. The effects of gasification temperature ($600{\sim}900^{\circ}C$) and partial pressure of steam (20~90 kPa) on the gasification rate were investigated. The three different types of gas-solid reaction models were applied to the experimental data to predict the behavior of the gasification reactions. The modified volumetric model predicted the conversion data well, thus the model was used to evaluate kinetic parameters in this study. The observed activation energy of biomass, sawdust and lignite gasification reactions were found to be in reasonable range and their rank was found to be sawdust > woodchip > lignite. The expression of apparent reaction rates for steam gasification of the three solids was proposed to provide basic information on the design of coal gasification processes.

• Food Science and Preservation
• /
• v.16 no.5
• /
• pp.714-718
• /
• 2009

Polyphenols are naturally occurring antioxidants and play many important roles in human health. Grape leaves have not yet been reported to contain the antioxidants. In this study, the physicochemical properties of powders from young grape leaves, obtained after hot-air or vacuum freeze drying, were analyzed. Weight loss rangedfrom 76-80%, but no difference was found between samples prepared by hot-air orvacuum freeze drying. The L-, a-, and b- values of grape powder all fell upon hot-air drying. Quercetin, resveratrol, catechin, and epicatechin were detected in all cultivars. The contents of the four polyphenols were generally higher in powders obtained by vacuum freeze dryingthan in those prepared by hot-air drying, indicating that vacuum freeze drying is better for optimal preservation of polyphenols. None of three polyphenols assayed was found in some cultivars or after certain drying treatments. Based on physiochemical properties, our findings suggest that powders obtained after vacuum freeze drying are optimal for industrial use.

• The Journal of Engineering Research
• /
• v.4 no.1
• /
• pp.69-85
• /
• 2002

The chemical composition of bottle glass is consisted of Na2O-CaO-SiO2. However the cullet is mornally used in order to decrease the melting tsmperature. This induce the productivity of bottle and decreases the cost. The addition of plate glass decreases the Al2O3 content and in fluence the stone phenomenon and devitification in botle glass. Tus the Feldspar is added in order to increase the Al2O3 content when plate cullet was added in melting. The Tridymite crystal was observed over 7.5% Al2O3 contents, which shown as white crystal in appearance. It is Supposed that the Wollastonite Would be occurred in more over 7.5% Al2O3. This fad id well consised With the Litertctures.

• Korean Journal of Food Science and Technology
• /
• v.32 no.5
• /
• pp.991-996
• /
• 2000

Enzyme-linked immunosorbent assay was developed for the analysis of soy protein in foods. Competitive indirect ELISA (ciELISA) was established by using specific antibodies against the heat-stable acidic subunits (AS) of glycinin. Soy proteins in each sample used in this study were solublized in the presence of urea and DTT and boiled at $100^{\circ}C$ for 1hr and then were renatured with a cystine-containing solution. After these treatments, each isolated soy protein (ISP) heated at 60, 70, 80, $90^{\circ}C$ for 10 minutes showed almost the same curve as unheated one in the ciELISA. The detection limit of ISP was 0.3 ${\mu}g/mL$. Anti-AS antibodies have very low reactivities less than 0.1% toward non-meat proteins such as skim milk and casein and did not show any reactivities toward egg white powder and ovalbumin. When laboratory-made sausages containing ISP of $0.5{\sim}3%$ were assayed by ciELISA, the mean recovery was about 83% (C.V., 19%). In addition, the average content of soy protein in commercial sausages was 1.27%.