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자동차 인스트루먼트 패널에 사용되는 플라스틱의 크리프 거동
김영삼(Young Sam Kim),전치훈(Chi Hoon Jeon),Erdenebat Tumur-Ochir,염영진(Young Jin Yum) 대한기계학회 2011 大韓機械學會論文集A Vol.35 No.12
자동차 인스트루먼트 패널에 사용되는 플라스틱의 온도와 시간에 따른 기계적 거동을 알아보기 위해 시편에 대한 인장 및 크리프 시험을 수행하였다. 여러 가지 온도에서의 물성치를 구한 결과 온도에 따라 물성치가 크게 변화함을 알 수 있었다. 4 가지 하중조건하에서의 3 점굽힘 크리프시험을 수행하고 지수법칙의 시간경화식을 적용하여 각종 계수를 구하고 크리프 거동을 간단한 식으로 표현하였다. 유한요소 크리프 해석 결과 하중이 커짐에 따라 수치해석 결과와 실험 결과가 차이가 커지지만 대체적으로 두 결과가 유사한 것을 확인할 수 있었다. Tensile and creep tests were performed at various temperatures to investigate the mechanical properties of plastics used in automotive instrument panels. Mechanical properties such as Young’s modulus and Poisson’s ratios changed markedly with the test temperature. Three-point bending creep tests were performed for three kinds of plastics under four loading conditions. Coefficients in the time-hardening power law creep equation were obtained from the experiment, and the creep behavior was represented by a simple expression. The results of finite element creep analysis showed good agreement with the experimental results, while the difference between the numerical and experimental results increased with the load.
유기용매 추출법에 의한 포플라의 전처리 및 당화 조건의 최적화
박정극,전영삼 東國大學校 1990 論文集 Vol.29 No.-
The effect of the pretreatment by solvent extraction with various solvent on the saccharification of poplar (Populus euramericana)was studied. The solvent system was phenol/H_2O (uncatalyzed, HCl and NaOH catalyzed), butanol/H_2O, ethanol/H_2O and ethylendiamine/H_2O solvent system. When the poplar was pretreated by phenol/H_2O uncatalyzed system, the best result of the enzymatic saccharification was total of 43.87 g/L reducing sugar produced and 83.35% of carbohydrated conversion was obatined at 190℃, 60 minutes. Total wood yield and the lignin removal were 46.3% and 96.17%, respectively. The use of acid, base catalyst and the others solvents was unsuitable to increase the efficiency of saccharification.
Jeon, Young Eun,Lee, Seok Cheol,Paik, Seung Sam,Lee, Kyeong Geun,Jin, So Young,Kim, Hyo Rim,Yoo, Chong Woo,Park, Hye Min,Han, Sang Yun,Choi, Dong Ho,Kim, Hark Kyun Blackwell Publishing Asia 2011 Pathology international Vol.61 No.8
<P>To date, protein profiles for hepatocellular carcinomas and cholangiocarcinomas have not been systematically evaluated and compared with each other in an unbiased way. Thirty‐six hepatocellular carcinomas and adjacent normal tissue samples were analyzed using histology‐directed, matrix‐assisted laser desorption/ionization (MALDI) mass spectrometry (MS). Four cholangiocarcinomas and adjacent normal tissue samples were also evaluated. Tissue samples were sectioned at 10 µm, with 1–3 sections thaw‐mounted on a conductive indium tin oxide‐coated glass slide. Sinapinic acid was manually deposited on areas of each tissue section enriched by epithelial cells, either tumor or normal, and mass spectra were acquired using a MALDI‐time of flight instrument. According to class prediction analysis, average prediction accuracy in test sets (composed of 18 hepatocellular carcinoma–normal pairs) ranged from 93.0 to 95.8%. Cholangiocarcinomas and hepatocellular carcinomas had different protein profiles, as evidenced by average prediction accuracy of >95% in the test set for all classifiers. Permutation <I>P</I>‐values for 0.632 + bootstrap cross validated misclassification rates (at feature selection <I>P <</I> 0.001) were less than 0.05 for predicting p53 immunostaining status. We conclude that MALDI MS profiles may be useful in assisting with the diagnosis and the differential diagnosis of primary liver cancers.</P>
Reduced electrical resistivity of reaction-sintered SiC by nitrogen doping
Jeon, Young-Sam,Shin, Hyunho,Lee, Young-Hyun,Kang, Sang-Won Cambridge University Press (Materials Research Soc 2008 Journal of materials research Vol.23 No.4
<P>A post heat treatment of reaction-sintered SiC at 1700 °C in nitrogen atmosphere significantly reduced electrical resistivity. A trace of insulating Si3N4 phase was detected via nitrogen heat treatment in high-resolution transmission electron microscopy observation; however, based on x-ray photoelectron spectroscopy, the evidence of nitrogen doping into SiC lattice has been claimed as the mechanism to the decreased resistivity. The increase of the total volume of SiC was apparent in x-ray diffraction during the nitrogen heat treatment, which was interpreted to stem from the growth of the nitrogen-doped intergranular SiC particles and surface doping of the primary SiC to reduce the contact resistance between the primary SiC particles.</P>
Jeon, Young-Sam,Shin, Hyun-Ho,Yoo, Dong-Joo,Yoon, Sang-Ok The Korean Ceramic Society 2012 한국세라믹학회지 Vol.49 No.1
An M-shaped SiC gas igniter was fabricated by a reaction sintering followed by nitrogen doping. The igniter showed both resistivity at room temperature and NTC to PTC transition temperature values that were lower than those of commercial igniters. It was deduced that the doped nitrogen reduces the electrical resistivity at room temperature, while, at high temperature, the doped nitrogen and a trace of $Si_3N_4$ phase work as scattering centers against electron transfer, resulting in a lowered NTC-to-PTC transition point (below $650^{\circ}C$). Such characteristics were correlated to the fast heating speed (as compared to the commercial models) and to the prevention of the high temperature overshooting of the nitrogen-doped SiC igniter.
Jeon, Beong-Sam,Park, Jeong-Won,Shin, Gab-Gyun,Kim, Beom-Kyu,Kim, Hee-Kyu,Song, Jae-Young,Cho, Young-Su,Cha, Jae-Young Korean Society of Life Science 2004 생명과학회지 Vol.14 No.3
초호열성 고세균 Thermococcus litoralis 유래의 4-$\alpha$-glucanotransferase는 클로닝 되어 염기배열이 밝혀졌으며, 대장균에서 발현되었다 발현된 이 효소는 기능적인 면에서는 D-enzyme과 유사하지만 아미노산 배열에서는 큰 차이점을 나타내었다. 이 효소는 cycloamylose를 생산하는 새로운 기능적인 특성을 가지고 있어 당대사 관련 효소 단백질에 관한 연구의 중요성 때문에 산업적으로 많은 각광을 받고 있다. 본 연구는 초호열성 고세균 T. litoris 유래 4-$\alpha$-glucanotransferase 유전자를 부위 특이적 변이 방법으로 재조합하여 lac와 T7프로모터를 이용해서 대장균 발현 벡터 시스템에서 대량발현 시켰다. 대장균에서 대량 발현된 재조합 효소 단백질은 열처리, 501빌Butyl-Toyopearl, Mono Q 크로마티그래피 방법에 의하여 간단히 정제되었다. 정제된 재조합 효소 단백질은 본래의 효소 단백질과 같은 기능을 가지고 있는 것으로 확인되었다. The gene encoding a extremely thermostable 4-$\alpha$-glucanotransferase from a hyperthermophilic archaeon, Thermococcus litoralis, was cloned, sequenced and expressed in Escherichia coli. The amino acid sequence of the enzyme was distantly related to other functionally-related ones, such as D-enzymes. The enzyme is of industrial interest because of a novel activity of producing cycloamylose and is also important for fundamental studies of protein, sugar-metabolizing enzymes. In this paper, the overexpression of 4-$\alpha$-glucanotransferase in E. coli was carried out expression vector system with lac and T7 promoters. The enzyme was successfully overexpressed, and purified by the heat treatment of a cell-free extract, successive Butyl-Toyopearl and Mono Q chromatographies. The purified recombinant enzyme showed the same specific activity and the same mobility in SDS-PAGE as natural enzyme.
Isolation and Characterization of Bacillus sp. BS-214 Producing Pectinase
Jeon,Beong Sam,Cha,Jae Young,Lee,Young Choon 한국생명과학회 2000 한국생명과학회 학술발표회 Vol.27 No.-
A bacterial strain BS-214 producing extracellular pectinase was isolated from soil. The isolated bacterium was identified as a strain of Bacillus sp. based on the morphological, biochemical, and physiological characteristics. Cell growth and pectinase activity of Bacillus sp. BS-214 were reached to maxium in the culture condition of pH 8.5 at 40℃. Production of pectinase by the strain was the highest when polygalacturonic acid was added to culture medium as a carbon source, and its optimal concentration was 1%. Also, yeast extract was used as the best nitrogen source for the production of pectinase by the concentration of 0.25%. Decomposition of a constituent of Edzeworthia papyrifera by the strain was observed by scanning electron microscope.
Purification and Some Properties of an Extracellular Pectinase from Bacillus sp. BS-214
Jeon, Beong-Sam,Song, Jae-Young,Lee, Gang-Deog,Kim, Beom-Kyu,Cha, Jae-Young,Lee, Young-Choon Korean Society of Life Science 2000 Journal of Life Science Vol.10 No.1
Pectinase was isolated from culture medium of Bacillus sp. BS-214 and purified 105-fold with 3.4% yield by ammonium sulfate precipitation, gel filteration using Sephadex G-75 and DEAE-cellulose followed by gel filteration through Sephadex G-100. The molecular weight of the purified enzyme was estimated to be about 43 kDa on SDS-PAGE and by gel filtration, indicating that the enzyme is a monomer. the optium pH and temperature of the enzyme were 9.0 and 55$^{\circ}C$, respectively. the enzyme was stable at 60$^{\circ}C$ for 30min and in a pH range from 7.5 to 10.5 for 12 h ant 4$^{\circ}C$. The enzyme activity was highly enhanced by Ca2+, and also K+, Li+ and Na+showed a positive effect, while stongly inhibited by Zn2+ and Hg2+.
Jeon, Young-Sam,Shin, Hyun-Ho,Park, Jin-Soo,Kang, Sang-Won The Korean Ceramic Society 2008 한국세라믹학회지 Vol.45 No.8
A series of reaction-sintered SiC was fabricated from preforms with varying volume fractions of two resin-coated SiC particles of different sizes (63 and $18{\mu}m$). The electrical resistivity and mechanical strength were eventually optimized at the small particle volume fraction of $0.3{\sim}0.4$, at which point the porosity of the preform was minimized. This study experimentally proves that additional processes after the formation of the preform, such as silicon infiltration and reaction sintering, do not apparently alter the optimum volume fraction of the preform packing, predicted by an existing analytical model based on solid packing. Thus, the volume fraction of particles of different sizes can be determined practically through the solid packing model to fabricate RSSCs with optimal properties.