• Applied Chemistry for Engineering
• /
• v.9 no.2
• /
• pp.193-199
• /
• 1998

The mixtures of ultra-high molecular weight polythylene (UHMWPE), high density polyethylene (HDPE), process oil (mineral oil) and potassium hexatitanate whisker were melted and mixed at $150^{\circ}C$ for 30min, and prepared by compression molding to the specimen of separator of about $200{\mu}m$ thickness at the same temperature and 5000 psi. Thereafter the pores were formed by extracting process oil with organic solvents. In this study, the range of PR (the ratio polymer to process oil) was varied from 0.1 to 0.5 because the specimen turned into rubbery phase at which PR was below 0.1 whereas it changed into gel phase at which PR was above 0.5. When the specimen was treated with nonpolar organic solvents, process oil was extracted nearly 98%. Tensile strength was $31kg/cm^2$ at PR = 0.426, and resistance of specimen was $37m{\Omega}/cm^2$ at PR = 0.186, and $53m{\Omega}/cm^2$ at PR = 0.426. The $N_2$ adsorption-desorption isotherm showed a hysteresis representing regions of capillary condensation, and the surface area at PR = 0.186 was relatively large as $130cm^2/g$. Potassium hexatitanate whisker was randomly dispersed in between PE layers. It might be that the whisker is intercalated through the PE thin layers oriented by compression.

• Microbiology and Biotechnology Letters
• /
• v.32 no.1
• /
• pp.52-59
• /
• 2004

When both fructose and galactose were added to a production medium as carbon sources, the productivity of PAFS (Psedomonas Antifungal Substance) biosynthesized by Pseudomonas aeruginosa was observed to be reduced significantly due to the well-known phenomenon of catabolite repression. In order to overcome this phenomenon by use of fermentation bioprocess, fed-batch cultivation method was examined. In addition, a high producer mutant strain, AP-20 obtained by a rational screening method was tested for its productivity of PAFS in both batch and fed-batch fermentation processes. Notably fed-batch operation showed approximately 4 fold higher PAFS productivity than traditional batch operation process. It was appeared that galactose was utilized principally for the cell growth of Pseudomonas aeruginosa whereas large portion of fructose was used for the biosynthesis of PAFS. Furthermore it was observed that composition and feeding rate of production media should be optimized even in the fed-batch fermentation bioprocess. As an example, very slow feeding of carbon sources gave rather negative effect on the production of PAFS due to significant limitation of carbon and energy sources available for the producer microorganism.

• 전기의세계
• /
• v.41 no.12
• /
• pp.21-30
• /
• 1992

내연기관의 가솔린자동차보다 역사가 오래된 전기자동차는 상대적으로 주생성능과 가격 경쟁력의 열세로 그 자취를 감추었고 최근까지 주로 특수목적의 단거리 저속차량으로 사용되고 있다. 그러나 1890년대 후반부터 전세계가 자동차배기가스에 의한 대기오염과 지구온난화 현상등의 문제를 심각하게 공감하게 되었고 마침내 미국 캘리포니아주에서는 전가자동차의 강제판매를 규정화하게 이르렀다. 이 규정에 의하면 1998년도부터 차량 판매대수의 2%를 전기자동차 판매로 강제요구하고 있다. 이 비율은 2000녀도에 5% 2003년에는 10%로 늘어날 계획이다. 따라서 미국에 많은 자동차를 수출하고 있는 일본, 독일 및 여러 유럽국가에서는 이 사업에 막대한 자금을 투자하며 개발에 몰두하고 있다. 미국의 Big3도 에너지성의 도움으로 최근 USABC를 결성하여 전기자동차 개발에 박차를 가하고 있다. 지금까지 기존의 가솔린자동차 기술에 있어서 일본과 독일에 상대적 열세에 있었던 미국도 이번 캘리포니아주의 전기자동차 강제판매 규정에 따른 전기자동차 사업으로 미국자동차 시장의 새로운 판도를 조성하겠다는 의도인듯하다. 국내에서도 정부가 이 사업의 중요성을 심각히 인식하고 G7사업과제의 하나로 선정하여 산, 학, 연 각층의 전문가가 참여하여 성공적으로 개발을 마칠 수 있도록 적극 지원하고 있다. 지금까지의 평균주행성능을 보면 최고속도 100-120km/h, 일층전 최대주행거리 150-200km 정도이며, 아직 양산체제에 돌입하지 않았기 때문에 가격면에서 경쟁력이 없는 실정이다. 그러나 1990년도에 들면서 각종 요소부품들의 기술수준이 급성장을 이루어서 앞으로 10년정도 후면 성능과 가격면에서 가솔린자동차와 대등한 수준의 전기자동차 개발이 실현될 수 있으리라 예측된다.는 영향받지 않았다. Clonidine의 심박수 감소작용은 .뇌실내및 정맥내 diltiazem이나 nifedipine 처리후에 감약되었다. 5). 뇌실내 clonidine$(30{\mu}g)$ 처 리후 뇌실내 diltiazem$(400{\mu}g)$과 nifedipine$(350{\mu}g)$의 혈압하강및 심박수 감소효과는 영향 받지 않고 그대로 나타났다. 이상의 결과로 diltiazem과 nifedipine은 가토뇌내에서 methoxamine에 의한 혈압상승의 작용점인 alrfia-1 adrenoceptor의 흥분에는 영향을 미치지 못하나 clonidine의 작용점인 alpha-2 adrenoceptor의 흥분에 의한 혈압하강및 심박수 감소효과는 억제한다고 추론하였다.thin 함량은 110.6 mg/L로서 산업적인 생산성이 있는 것으로 나타났다. 이번 연구를 통하여 개발된 변이주 B76 및 이의 대량 발효를 위한 최종조건의 정립은 향후 astaxanthin의 산업적 생산공정에 필요한 기초자료로 이용될 것으로 기대된다.색총말내에 소형의 도형, 소형의 장형 연접소포 및 DENSE CORE VESICLE의 3가지 연접소포를 가지고 있었고 출현빈도수는 촉각엽에서 가장 큰 33%이었다. 제5형 신경연접은 축색종말내에 중등도크기의 원형, 대형의 원형연접소포 및 DENSE CORE VESICLE을 포함하였고 13%의 출현빈도수로 관찰되었다. 배추횐나비의 촉각에 있는 지각신경세포가 뇌의 촉각엽으로 뻗어 들어가 위의 5가지 신경연접중 어느 형을 형성하는지를 관찰하기 위하여 좌측 촉각의 기부를 제거하여 지각신경세포를 절단하였는데 그 결과, 좌측 촉각엽에서 제4형의 신경연접이 퇴행성 변화를 나타내었다.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.14 no.4
• /
• pp.401-408
• /
• 1985

The yeast cell wall lytic action of the alkaline AL-protease, which was found out of the crude Zymolyase that a kind of yeast cell wall lytic $endo-{\beta}-1$, 3-glucanase produced from Arthrobacter luteus, was investigated with the viable cells of S. sake and it's cell wall preparation. AL-protease on the lysis of the viable yeast cells showed very low activities with the alone, but the lytic activities were highly increased with the combination of AL-protease and Zymolyase. On the stepwise treatment of the viable yeast cells with AL-protease and Zymolyase, the cells were lysed highly only by the course having a treatment with Zymolyase after pretreatment with AL-protease. Thus synergistic action of AL-protease was not observed with any some commercial enzymes, known as a type of alkaline and serine protease such as AL-protease, and was also found to be affected greatly by the culture conditions and species of the yeast tested. AL-protease caused the release of some peptide and a lot of sugar from the cell wall preparation, but could not lysed the cell wall more than 66%. Whereas Zymolyase could lysed the cell walls almost completely with alone. On the basis of these results, the synergistic action of AL-protease on the lysis of S. sake cells is hypothesized that at first AL-protease bind to the yeast cell surface layer consisting of mannan and protein, and then changes their conformation to facilitate the penetration of Zymolyase from the outside to the inside framework layer constituted of alkali insoluble ${\beta}-1,\;3-glucan$.

• The Journal of the Korean life insurance medical association
• /
• v.12
• /
• pp.50-55
• /
• 1993

After a short historical resume, screening is discussed on the basis of the current philosophy of Life insurance compaines in leading countries. This is followed by considerations with regard to the future in areas of major bearing on Life insurance screening which have emerged as important within the last decade. HIV-antibody testing is dealt with from the screening point of view followed by aspects regarding the applicability of tumour marker use in Life insurance medicine. Last but not least genetic testing will be addressed, taking into account prospects for the future, as well as the resulting responsibility in medical and underwriting terms. The major considerations and suggested guidelines can be summarized as follows: 1) Screening in Life insurance is a prerequisite for underwriting and is a well-functioning selection instrument. 2) Screening technologies are medically well defined and have to follow general clinical rules, also in the future. 3) Screening parameters should follow the patterns of diseases according to age and risk groups. 4) Screening parameters for prognostic use are legitimate as long as they are considered in conjuction with clinical medical observations and rules. 5) Screening technologies of a sensitive nature require very special rules for handling in the sense of "consequential ethies". 6) Screening parameters like HIV-antibody testing require ongoing scientific feedback in their new testing dimensions. 7) Screening in the form of genetic testing is as yet not used in Life insurance; its potential future role in Life insurfance medicine must, however, be discussed responsibly and in time. 8) Screening enables the insurance industry to rule out possible antiselection and provide for equal knowledge on the part of the insurance applicant and the insurer about impairements which shorten life expectancy. 9) Screening, informed consent, counselling and confidentiality must go hand in hand both now and to an even greater extent in the future.

• Korean Journal of Microbiology
• /
• v.44 no.2
• /
• pp.93-97
• /
• 2008

RraA is a recently discovered protein inhibitor that regulates the enzymatic activity of RNase E, which plays a major role in the decay and processing of RNAs in Escherichia coli. It has also been shown to regulate the activity of RNase ES, a functional Streptomyces coelicolor ortholog of RNase E, which has 36% identity to the amino-terminal region of RNase E. There are two open reading frames in S. coelicolor genome that can potentially encode proteins having more than 35.4% similarity to the amino acid sequence of RraA. DNA fragment encoding one of these RraA orthologs, designated as RraAS2 here, was amplified and cloned in to E. coli vector to test whether it has ability to regulate RNase E activity in E. coli cells. Co-expression of RraAS2 partially rescued E. coli cells over-producing RNase E from growth arrest, although not as efficiently as RraA, induced by the increased ribonucleolytic activity in the cells. The copy number of ColEl-type plasmid in these cells was also decreased by 14% compared to that in cells over-producing RNase E only, indicating the ability of RraAS2 to inhibit RNase E action on RNA I. We observed that the expression level of RraAS2 was lower than that of RraA by 4.2 folds under the same culture condition, suggesting that because of inefficient expression of RraAS2 in E. coli cells, co-expression of RraAS2 was not efficiently able to inhibit RNase E activity to the level for proper processing and decay of all RNA species that is required to restore normal cellular growth to the cells over-producing RNase E.

• Korean Journal of Microbiology
• /
• v.52 no.3
• /
• pp.336-343
• /
• 2016

A mannanase gene was cloned into Escherichia coli from Cellulosimicrobium sp. YB-43, which had been found to produce two kinds of mannanase, and sequenced completely. This mannanase gene, designated manB, consisted of 1,284 nucleotides encoding a polypeptide of 427 amino acid residues. Based on the deduced amino acid sequence, the ManB was identified to be a modular enzyme including two carbohydrate binding domains besides the catalytic domain, which was highly homologous to mannanases belonging to the glycosyl hydrolase family 5. The N-terminal amino acid sequence of ManB, purified from a cell-free extract of the recombinant E. coli carrying a Cellulosimicrobium sp. YB-43 manB gene, has been determined as QGASAASDG, which was correctly corresponding to signal peptide predicted by SignalP4.1 server for Gram-negative bacteria. The purified ManB had a pH optimum for its activity at pH 6.5~7.0 and a temperature optimum at $55^{\circ}C$. The enzyme was active on locust bean gum (LBG), konjac and guar gum, while it did not exhibit activity towards carboxymethylcellulose, xylan, starch, and para-nitrophenyl-${\beta}$-mannopyranoside. The activity of enzyme was inhibited very slightly by $Mg^{2+}$, $K^+$, and $Na^+$, and significantly inhibited by $Cu^{2+}$, $Zn^{2+}$, $Mn^{2+}$, and SDS. The enzyme could hydrolyze mannooligosaccharides larger than mannobiose, which was the most predominant product resulting from the ManB hydrolysis for mannooligosaccharides and LBG.

• KOREAN JOURNAL OF CROP SCIENCE
• /
• v.32 no.4
• /
• pp.447-454
• /
• 1987

Five soybean varieties of two early maturing; Karikei 73 and SS79168, and three late maturing; Tohoku 76, Baegunkong and Jangbaegkong, were used and evaluated in the study, Of the varieties examined, Karikei 73 was characterized by the delayed leaf senescence, To investigate the periodical trends of sugars in plant organs and their roles to the nitrogen fixing activity of root nodules, the concentrations of reducing and non-reducing sugar in root and nodules during the grain filling period were measured. The concentration of non-reducing sugar in roots was not changed up to the stage of R6 for all of the varieties but it decreased rapidly thereafter for the varieties except Karikei 73. No such rapid decrease in the concentration of non-reducing sugar in the roots was observed for Karikei 73 having the characteristics of delayed leaf senescence. The concentration of reducing sugar in the root nodules was not greatly changed for all of the varieties up to the stage of R6 regardless of the earliness of varieties but increased temporarily at R6.5 when there was a rapid decrease in ARA. The phenomenon explained the fact that nitrogen fixing activities were controlled not only by supplying sugars as the source of energy for nitrogen fixation, but also by the need for fixed nitrogen of the plant. The concentration of non-reducing sugar in root nodules also increased up to the stage of R6-R6.5 but decreased at R7, which could apply the same explanation as in the concentration of reducing sugar of the root nodules.

• School Mathematics
• /
• v.15 no.3
• /
• pp.603-617
• /
• 2013

The major purpose of this article is to examine what kind of gap exists between mathematically gifted students' probability knowledge and the reality actually applying that knowledge and then analyze the cause of the gap. To attain the goal, 23 elementary mathematically gifted students at the highest level from G region were provided with problem situations internalizing a probability and expectation, and the problems are in series in which conditions change one by one. The study task is in a gaming situation where there can be the most reasonable answer mathematically, but the choice may differ by how much they consider a certain condition. To collect data, the students' individual worksheets are collected, and all the class procedures are recorded with a camcorder, and the researcher writes a class observation report. The biggest reason why the students do not make a decision solely based on their own mathematical knowledge is because of 'impracticality', one of the properties of probability, that in reality, all things are not realized according to the mathematical calculation and are impossible to be anticipated and also their own psychological disposition to 'avoid loss' about their entry fee paid. In order to provide desirable probability education, we should not be limited to having learners master probability knowledge included in the textbook by solving the problems based on algorithmic knowledge but provide them with plenty of experience to apply probabilistic inference with which they should make their own choice in diverse situations having context.

• Korean Journal of Environmental Agriculture
• /
• v.3 no.1
• /
• pp.63-70
• /
• 1984

The terrestrial UV flux rapidly increased in late spring, as measured by the chemical actinometry at two elevations (near sea level and 1,100m above sea level) on Jeju Island. More intense UV fluxes were observed at higher altitudes. Any harmful effects of solar UV-B on the growth of soybean were not detected in UV-B-exclusion experiment. To ascertain the effect of UV radiation on vegetative growth, intact (㏖ wt 124000) and large (${\sim}120000$) phytochromes were irradiated with UV-B radiation. In intact phytochrome, the Pfr form accounts for 60% of the total phytochrome under stationary state conditions, whereas it accounts for 50% in large phytochrome. Calculated quantum yields for the forward and the backward phototransformations of phytochrome by UV were ${\phi}r=0.016$ and ${\phi}fr=0.010$ in intact phytochrome, and ${\phi}r={\phi}fr=0.012$ in large phytochrome, respectively.