• 미생물학회지
• /
• 제19권3호
• /
• pp.137-141
• /
• 1981

Occurrence and distribution of sucrose metabolizing enzymes in oral streptococci had been studied. In these studies, the carbohydrate component of the culture medium had been glucose. I have extended these studies by analyzing bacterial culture supernatants for the relative content of hexosyltransferases, namely glucosyl and fructosyltransferase. As a carbohydrate, fructose was used. The growth measured for nine oral streptococci (Strptococcus mutans strains BHT, ING, AHT, 6715, LM-7, and SL-1 ; Streptococcus sanguis 903, 9811, and M-5) varied. The level of glucosyltansferase activity also varied among S. mutans strains, and its level in S. sanguis was relatively low. Fructosyltansferase activity of the various strains fluctuated more than of glucosyltransferase. S.mutans strain LM-7 had significantly higher level of both enzymes. As a whole, fructose-grown cultures had generally an agreeable trend of enzyme activity to those from glucose-grown cultures.

• 한국생물공학회:학술대회논문집
• /
• 한국생물공학회 2000년도 추계학술발표대회 및 bio-venture fair
• /
• pp.500-503
• /
• 2000

미생물을 이용한 새로운 독성 측정 방법으로서, 본 연구에서는 자성 박테리아 Magnetospirillum sp. AMB-1 세포들의 유영 속력 측정을 통한 독성 측정의 가능성과, 발광 박테리아를 이용한 기존의 $Microtox^{circledR}$ 시스템에 견줄 수 있는 새로운 독성 측정 방법이라는 사실을 확인하였다. 또한, AMB-1 세포들의 주기성 관찰을 통해 또 다른 독성 측정 방법의 가능성을 확인하였다.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2003년도 춘계학술대회 논문집
• /
• pp.1495-1498
• /
• 2003

Recently, self-healing methods of a cracked matrix, especially polymeric composite materials, became the center of engineering researchers. In this paper, we summarized the self-healing concept for polymeric composite materials and investigated the effect of microparticle on the crack growth behavior in colorless and transparent matrix by experimental observation to describe the crack propagation around the microparticle inside epoxy matrix composite. Compression splitting test for the specimen involving microparticle was conducted. In addition, FE analysis was pursued to present the stress contour around microparticle in the matrix. Through the experiments and FE analysis, we found that the size. relative position, bonding condition and relative stiffness of microparticle are important parameters to decide the direction of crack propagation, which is related to the rupture of microparticle for self-healing

• 한국신뢰성학회지:신뢰성응용연구
• /
• 제15권3호
• /
• pp.216-221
• /
• 2015

Sintering behavior of 3%yttria-stabilized zirconia was comparatively studied using a spray-dried powder produced by a domestic and global company. Quality of the sintered block was analysed in terms of relative density, shrinkage rate, grain growth, hardness, and fracture toughness. Relative density, shrinkage rate, and hardness value of the finally sintered block was similar between domestic and global zirconia powder, respectively. But, flexural strength of the domestic powder specimen was about 70% of the sintered block produced by using a global powder. The poor sintering quality of the domestic powder was discussed in relation with compressibility of the spray-dried granule-type powder and the amount of monoclinic phase in the as-received powder.

• Corrosion Science and Technology
• /
• 제9권4호
• /
• pp.171-174
• /
• 2010

MAO (micro-arc oxidation) is an eco-friendly convenient and effective technology to deposit high-quality oxide coatings on the surfaces of Ti, Al, Mg and their alloys. The roles of the electrolyte concentration and relative cathode electrode area sizes in the grown oxide film during titanium MAO were investigated. The higher the concentration of the electrolyte, the lower the $R_{total}A$ value. The oxide film produced by the lower concentration of the electrolyte is thinner and less uniform than the film by the higher concentration, which is thick and porous. The cathode area size must be bigger than the anode area size in order to minimize the voltage drop across the cathode. The ratio of the cathode area size to the anode area size must be bigger than 8. Otherwise, the cathode will be another source for voltage drop, which is detrimental to and slows down the oxide growth.

• 한국안전학회지
• /
• 제25권6호
• /
• pp.9-13
• /
• 2010

An experimental study for characteristics of soot were conducted at the post-flame region in jet diffusion flames, where carbon dioxide was used as additives in oxidizer stream. Light-extinction method was performed using He-Ne laser with wave length at 632.8nm for the measurement of relative soot density and soot volume fraction with dimensionless extinction coefficient, $K_e$ and mass specific extinction coefficient, ${\sigma}_s$. To increase of resolution, laser light was modified for sheet-form using concave, convex lenses and slit. C/H ratio was introduced for quantitative analysis of soot growth which is expressed by carbonization and dehydrogen. Also transmission electron microscopy(TEM) was used for observation of morphological shape. The results show that the relative soot density in the post-flame region was lower when carbon dioxide was added in oxidizer stream because of reduction of flame temperature.

• 한국약용작물학회지
• /
• 제21권5호
• /
• pp.348-352
• /
• 2013

This study was carried out to investigate the effect of sucrose, boric acid, and calcium nitrate in optimum pH and relative humidity on pollen germination and pollen tube growth of boxthorn (Lycium chinense M.). Medium containing 100mg/L of $H_3BO_3$ showed maximum pollen germination and pollen tube elongation, 64.8% and $920{\mu}m$. Additionally supplied calcium nitrate to the medium lowered pollen germination rate and pollen tube elongation. Here we report the optimum conditions for the pollen germination and pollen tube development was observed at 10% sucrose, 1.0% agar, pH 6.0, and 100% relative humidity.

• 무역학회지
• /
• 제44권4호
• /
• pp.35-49
• /
• 2019

This study aims to determine whether the export volume of export country is affected by the strengthening of environmental management level of the importing country depending on the relative technology level of the importing country. To this end, a gravity model was established and the relative size of environmental management level was introduced, and how it affects the export was analyzed according to the difference of environmental management level between Korea and the importing country. The analysis of Korean industry by technology level (based on R&D investment) shows that countries with higher environmental management levels increase exports in both high and low technologies compared to Korea. On the other hand, exports of high-tech industries did not affect export growth in countries with lower environmental management than Korea.

• 한국연초학회지
• /
• 제4권2호
• /
• pp.41-50
• /
• 1982

To investigate tile effects of growth characteristics on the yield, price per Kg, chemical contents and physical properties in Burley tobacco, ten varieties including Burley 21 were tested in this study. The results obtained are summarized as follows. 1 Forty to fifty days after transplanting, CCR (Crop Growth Rate) was the highest. RCR (Relative Growth Rate) increased up to 40 days, but decreased 50 days when maturation began. High- yielding varieties showed high CCR and RCR till 60 days. 2. Total alkaloid content of cured leaf increased about three times than that of topping stage, but the increased rates were some what different among varieties. 3. Leaf area, stalk diameter, stalk height and days to flower showed positive correlations to yield, whereas leaf thickness and weight per unit leaf area showed negative. 4 Varieties which are high in cured leaf weight ratio and weight per unit leaf thickeners showed relatively poor quality. 5 Nitrogen content was high in leafy and larger stalk diameter variety. 6. There are positive correlation between weight per unit leaf thickness and filling power. The time of combustion was positively correlated to leaf thickness and weight Per unit leaf. 7. It can be concluded that many characteristics are related to the yield, but not quality. It is, there fore, easy to Predict tile yield, but difficult to forecast the qualiffy.

• Journal of Animal Science and Technology
• /
• 제55권4호
• /
• pp.295-301
• /
• 2013

This study was conducted to evaluate the effects of chelated Cu and Zn on growth performance, nutrient digestibility, blood profiles, and fecal noxious gas emission in weanling pigs. A total of 90 weanling pigs with an initial body weight (BW) of $5.27{\pm}0.04kg$ were randomly allotted to two dietary treatments for 42 d. Pigs were then fed a control diet (CON) or a Zinpro diet (CON + 0.1% chelate copper and zinc). There were nine replicate-pens with five pigs in each pen. During d 0 to 14 and d 14 to 28, the ADFI decreased (p<0.05) and the G/F increased (p<0.05) in pigs fed the Zinpro diet compared with those that received the CON diet. During d 28 to 42, the ADFI increased (p<0.05) in pigs fed the Zinpro diet relative to those fed the CON diet. Additionally, the apparent total tract digestibility of DM, N, and energy increased (p<0.05) in the Zinpro group when compared to the CON group on d 14 and 28. The lymphocyte percentage was also greater (p<0.05) in the Zinpro group than in the CON group. Overall, dietary supplementation with 0.1% chelate copper and zinc improved the growth performance and nutrient digestibility in weanling pigs.