• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.1220-1221
• /
• 2006

[ $LiMn_2O_4$ ] powders for lithium ion batteries were synthesized from two separate raw material pairs of LiOH/MnO and $LiOH/MnO_2$. The powders prepared at 780 and $850^{\circ}C$ and their difference of electrochemical properties were investigated. Both powders calcined at 780 and $850^{\circ}C$ were composed of a single-phase spinel structure but those treated at $850^{\circ}C$ showed a lower intensity ratio of $I_{311}$ to $I_{400}$, a slightly larger lattice parameter, and an increased discharge capacity by 10% under $3.0{\sim}4.3V$ voltage range. The XPS study on the oxidation states of manganese repealed that powders made from LiOH/MnO had less $Mn^{3+}$ ion and gave better battery performances than those from $LiOH/MnO_2$.

• Journal of Astronomy and Space Sciences
• /
• v.6 no.1
• /
• pp.57-72
• /
• 1989

A total of 80 photographs on 29 nights and another total of 44(22 each in B and V) photoelectric observations on 6 nights are secured for P/Halley(1982 ⅰ) for seven months before and after the perihelion passage. The photographic observations have been mode at different places depending on the position of the comet and the development of the tail, while the photoelectric observations were made only with 61-cm reflector at Yonsei University Observatory(YUO). Four most representative photographs are presented only to illustrate the remarkable features of the comet. The second one of these shows a coma with a possible flash activity on 1985 SEPT. 18.56 UT. The third one shows the largest tail recorded among our plates, and the last one prepresents unusual record made on northern hemisphere at a latitude as high as about $33^{circ}$12' N on the occasion of the comet's second perigee on 1976 APR. 11.6 UT. Photoelectric observations, on the other hand, determine the V and B-V of the total and the coma of the comet before its perihelion passage, and exhibit the light variations of 0m.6 in V in an hour and a half. Two new sets of m and n, one before and the other after the perihelion passage, determined based on the collected data, but the values are dissimilar one another significantly.

• Journal of Microbiology and Biotechnology
• /
• v.21 no.9
• /
• pp.885-892
• /
• 2011

The bacterial communities in the intestinal tracts of earthworm were investigated by culture-dependent and -independent approaches. In total, 72 and 55 pure cultures were isolated from the intestinal tracts of earthworms under aerobic and anaerobic conditions, respectively. Aerobic bacteria were classified as Aeromonas (40%), Bacillus (37%), Photobacterium (10%), Pseudomonas (7%), and Shewanella (6%). Anaerobic bacteria were classified as Aeromonas (52%), Bacillus (27%), Shewanella (12%), Paenibacillus (5%), Clostridium (2%), and Cellulosimicrobium (2%). The dominant microorganisms were Aeromonas and Bacillus species under both aerobic and anaerobic conditions. In all, 39 DNA fragments were identified by polymerase chain reaction-denaturing gradient gel electrophoresis (PCR-DGGE) analysis. Aeromonas sp. was the dominant microorganism in feeds, intestinal tracts, and casts of earthworms. The DGGE band intensity of Aeromonas from feeds, intestinal tracts, and casts of earthworms was 12.8%, 14.7%, and 15.1%, respectively. The other strains identified were Bacillus, Clostridium, Enterobacter, Photobacterium, Pseudomonas, Shewanella, Streptomyces, uncultured Chloroflexi bacterium, and uncultured bacterium. These results suggest that PCR-DGGE analysis was more efficient than the culturedependent approach for the investigation of bacterial diversity and the identification of unculturable microorganisms.

• Restorative Dentistry and Endodontics
• /
• v.28 no.2
• /
• pp.162-168
• /
• 2003

이 연구는 기존의 레진 근관봉함재를 보완하여 개발한 근관봉함재(Adseal; 새로운 레진 계통의 근관봉함재)를 이미 상품화된 레진 계통의 근관봉함재(AH 26, AH Plus), 산화 아연 유지놀 계통의 근관봉함재(TubliSeal EWT, Pulpcanal sealer EWT), 수산화 칼슘 계통의 근관봉함재(Sealapex)와 비교하여 세포독성과 항균작용을 평가하고자 한다. 세포독성 실험은 L929 쥐의 섬유아세포를 사용하여 세포의 viable ratio를 계산한 후, Giemsa stain으로 염색하여 세포의 양상을 관찰하였고, 항균작용 실험은 Enterococcus faecalis Porphyromonas endodontalis, Porphyomonas gingivalis, Prevotella intermedia, Fusobacterium nucleatum 와 Fusobacterium necrophorum를 사용하여 agar diffusion test로 평가한다. Adseal은 다른 근관봉함재에 비해 훨씬 낮은 세포독성을 보였고, AH Plus, AH 26, TubliSeal EWT, Sealapex, Pulpcanal sealer EWT의 순으로 세포독성의 정도가 높아짐을 알 수 있었다. 또한 Adseal은 Enterococcus faecalis 에서는 낮은 항균작용을 보이지만, Black-pigmented bacteria 에서는 높은 항균작용을 보이는데, 모든 근관봉함재는 서로 다른 종에 따라 어느 정도의 항균효과를 가지고 있음을 알 수 있었다.

• Proceedings of the Korean Biophysical Society Conference
• /
• 2003.06a
• /
• pp.70-70
• /
• 2003

Active sites and substrate bindings of 1-aminoxyclopropane-1-carboxylate oxidase (MD-ACO1) catalyzing the oxidative conversion of ACC to ethylene have been determined based on site-directed mutagenesis and comparative modeling methods. Molecular modeling based on the crystal structure of Isopenicillin N synthase (IPNS) provided MD-ACO1 structure. MD-ACO1 protein folds into a compact jelly roll shape, consisting of 9 ${\alpha}$-helices, 10 ${\beta}$-strands and several long loops. The MD-ACO1/ACC/Fe(II)/Ascorbate complex conformation was determined from automated docking program, AUTODOCK. The MD-ACO1/Fell complex model was consistent with well known binding motif information (HIS177-ASP179-HIS234). The cosubstrate, ascorbate is placed between iron binding pocket and Arg244 of MD-ACO1 enzyme, supporting the critical role of Arg244 for generating reaction product. These findings are strongly supported by previous biochemical data as well as site-directed mutagenesis data. The structure of enzyme/substrate suggests the structural mechanism for the biochemical role as well as substrate specificity of MD-ACO1 enzyme.

• Journal of Fisheries and Marine Sciences Education
• /
• v.28 no.4
• /
• pp.1014-1023
• /
• 2016

The purpose of this study is to suggest improvement directions and strategies for the minimization of ex-post damage and prevention of the generation of derelict fishing gear which lead to decreased fisheries resources and deteriorated marine ecosystem through ghost fishing and damaging spawning and growth grounds. Current problems related to derelict fishing gear in Korea are lack of reliable data on the generation amount of derelict fishing gear, absence of life-cycle monitoring and management system, insufficient supports for derelict fishing gear collection programs and R&D investment in environmentally friendly fishing gear, etc. Thus, this study suggests three basic improvement directions to prevent the generation and minimize the damage of derelict fishing gear. Such improvement directions contain more detailed strategies such as establishment of fishing gear management law and life-cycle management system, strengthening entry regulations on fisheries causing serious ghost fishing problems, increased supports for R&D investment and dissemination of bio-degradable fishing nets, and promotion of voluntary agreements among competing fishermen's groups.

• Archives of Pharmacal Research
• /
• v.28 no.11
• /
• pp.1239-1243
• /
• 2005

A new norditerpenoid and a known alkaloid were isolated from the alkaloidal fraction of the processed tubers of Aconitum carmichaeli. The structure of the new norditerpenoid alkaloid was elucidated as lipoforesaconitine (1) on the basis of spectroscopic analysis. The known norditerpenoid alkaloid was characterized as lipoyunanaconitine (2). In addition, a new flavonoid, 6'-O-acetylliquiritin (7), along with a known ceramide, (2S,3S,4R,8E)-2-[(2'R)-2'­hydroxylignoceroylamino]-8(E)-octadecene-1,3,4-triol (3), as well as a known steroid saponin, gracillin (8), and three known flavonoids, Iiquiritigenin (4), isoliquiritigenin (5), and liquiritin (6), were also isolated and characterized. All known compounds were isolated from this plant for the first time. The structures of the isolates were established by spectroscopic and chemical methods.

• Archives of Pharmacal Research
• /
• v.20 no.2
• /
• pp.148-154
• /
• 1997

The antioxidant activity of Artemisia iwayomogi was determined by measuring the radical scavenging effect on 1, 1-diphenyl-2-picrylhydrazyl (DPPH) radical. The methanol extract of A. iwayomogi showed strong antioxidant activity, and thus fractionated with several solvents. The antioxidant activity potential of the individual fraction was in the order of ethyl acetate > n-butanol > water > chloroform > n-hexane fraction. The ethyl acetate and n-butanol soluble fractions exhibiting strong antioxidant activity were further purified by repeated sitica get and Sephadex LH-20 column chromatography. Antioxidant chlorogenic acid was isolated as one of the active principles from the n-butanol fraction, together with the inactive components, 1octacosanol, scopoletin, scopolin, apigenin $7, 4^{I}$-di-O-methylether, luteolin $6, 3^{I}$-di-O-methylether (jaceosidin), apigenin methylether (genkwanin), 2, 4-dihydroxy-6-methoxyacetophenone $4-O-{\beta}-$D-glucopyranoside and quebrachitol. The antioxidant activity of chlorogenic acid was comparable to that of L-ascorbic acid, which is a well known antioxidant.

• Proceedings of the KSR Conference
• /
• 2004.10a
• /
• pp.1353-1359
• /
• 2004

There are many massive components added on the railway overhead-line. These components cause larger fluctuations of contact forces, which are due to wave reflections and Doppler effects when a high-speed train passes those. In this paper, mathematical formula are derived for the relation between the added mass and contact force fluctuations. Using the derived formula, we calculate a added mass on the overhead-line which cause amplification factor to become 2.5. German design practice requires that amplification factor due to the wave reflection should be less than 2.5 to obtain good current collection performance. To show the validity of the formula, simulation results are compared with the calculation results. Simulation results showed that contact force fluctuations grow rapidly when an added mass is larger than the calculation result. Therefore, the simple form of formula can be used for estimating maximum added mass not to cause large fluctuations of contact forces in early design phase.

• Journal of Institute of Control, Robotics and Systems
• /
• v.1 no.1
• /
• pp.4-12
• /
• 1995

In the sense of eigenstructure (eigenvalues/eignenvectors) assignment, the effectiveness and disturbance suppressibility of a controller depend mainly on the left eigenstructure (eignevalues/left eigenvectors) of a system. On the other hand, the disturbance decouplability is governed by the right eigenstructure (eignevalues/right eigenvectors) of the system. In this paper, in order to obtain a disturbance decouplable as well as effetive and disturbance suppressible controller, a concurrent assignment methodology of the left and right eigenstructure is proposed. The biorthogonality condition between the left and right modal matrix and state selection matrices are used to develop the methodology. The proposed concurrent eigenstructure assignment methodology guarantees that the desired eigenvalues are achieved exactly and the desired left and right eigenvectors are assigned to the best possible (achievable) sets of eigenvectors in the least square sense, respectively. A numerical example is presented to illustrate the validity and usefulness of the proposed methodology.