• 한국분말재료학회지
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• 제19권3호
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• pp.210-214
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• 2012

Mass production-capable $Li_2MnSiO_4$ powder was synthesized for use as cathode material in state-of-the-art lithium-ion batteries. These batteries are main powder sources for high tech-end digital electronic equipments and electric vehicles in the near future and they must possess high specific capacity and durable charge-discharge characteristics. Amorphous silicone was quite superior to crystalline one as starting material to fabricate silicone oxide with high reactivity between precursors of sol-gel type reaction intermediates. The amorphous silicone starting material also has beneficial effect of efficiently controlling secondary phases, most notably $Li_xSiO_x$. Lastly, carbon was coated on $Li_2MnSiO_4$ powders by using sucrose to afford some improved electrical conductivity. The carbon-coated $Li_2MnSiO_4$ cathode material was further characterized using SEM, XRD, and galvanostatic charge/discharge test method for morphological and electrochemical examinations. Coin cell was subject to 1.5-4.8 V at C/20, where 74 mAh/g was observed during primary discharge cycle.

• 한국우주과학회:학술대회논문집(한국우주과학회보)
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• 한국우주과학회 2009년도 한국우주과학회보 제18권2호
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• pp.30.2-30.2
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• 2009

There is a growing body of evidence for the presence of multiple stellar populations in some globular clusters, including NGC 1851. For most of these peculiar globular clusters, however, the evidence for the multiple red giant-branches (RGBs) having different heavy elemental abundances as observed in $\omega$ Centauri is hitherto lacking, although spreads in some lighter elements are reported. It is therefore not clear whether they also share the suggested dwarf galaxy origin of $\omega$ Cen or not. Here we show from the CTIO 4m UVI photometry of the globular cluster NGC 1851 that its RGB is clearly split into two in the U - I color. The two distinct RGB populations are also clearly separated in the abundance of heavy elements as traced by Calcium, suggesting that the type II supernovae enrichment is also responsible, in addition to the pollutions of lighter elements by intermediate mass asymptotic giant branch stars or fast-rotating massive stars. The RGB split, however, is not shown in the V - I color, as indicated by previous observations. Our stellar population models show that this and the presence of bimodal horizontal-branch distribution in NGC 1851 can be naturally reproduced if the metal-rich second generation stars are also enhanced in helium.

• Journal of Microbiology and Biotechnology
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• 제26권2호
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• pp.347-355
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• 2016

An exo-β-D-glucosaminidase (AorCsxA) from Aspergillus oryzae FL402 was heterologously expressed and purified. The deduced amino acid sequence indicated that AorCsxA belonged to glycoside hydrolase family 2. AorCsxA digested colloid chitosan into glucosamine but not into chitosan oligosaccharides, demonstrating exo-β-D-glucosaminidase (CsxA) activity. AorCsxA exhibited optimal activity at pH 5.5 and 50℃; however, the enzyme expressed in Pichia pastoris (PpAorCsxA) showed much stronger thermostability at 50℃ than that expressed in Escherichia coli (EcAorCsxA), which may be related to glycosylation. AorCsxA activity was inhibited by EDTA and most of the tested metal ions. A single amino acid mutation (F769W) in AorCsxA significantly enhanced the specific activity and hydrolysis velocity as revealed by comparison of V_max and k_cat values with those of the wild-type enzyme. The three-dimensional structure suggested the tightened pocket at the active site of F769W enabled efficient substrate binding. The AorCsxA gene was heterologously expressed in P. pastoris, and one transformant was found to produce 222 U/ml activity during the high-cell-density fermentation. This AorCsxA-overexpressing P. pastoris strain is feasible for large-scale production of AorCsxA.

• Journal of Microbiology and Biotechnology
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• 제24권11호
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• pp.1464-1472
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• 2014

The microbial community structures of two continuous stirred tank reactors digesting turkey manure with pine wood shavings as well as chicken and swine manure were investigated. The reactor fed with chicken/swine wastes displayed the highest organic acids concentration (up to 15.2 g/l) and ammonia concentration (up to 3.7 g/l ammonium nitrogen) and generated a higher biogas yield (up to $366ml/g_{VS}$) compared with the reactor supplied with turkey wastes (1.5-1.8 g/l of organic acids and 1.6-1.7 g/l of ammonium levels; biogas yield was up to $195ml/g_{VS}$). The microbial community diversity was assessed using both sequencing and profiling terminal restriction fragment length polymorphisms of 16S rRNA genes. Additionally, methanogens were analyzed using methyl coenzyme M reductase alpha subunit (mcrA) genes. The bacterial community was dominated by members of unclassified Clostridiales with the prevalence of specific clostridial phylotypes in each reactor, indicating the effect of the substrate type on the community structure. Of the methanogenic archaea, methanogens of the genus Methanosarcina were found in high proportions in both reactors with specific methanosarcinas in each reactor, whereas the strict hydrogenotrophic methanogens of Methanoculleus sp. were found at significant levels only in the reactor fed with chicken/swine manure (based on the analyses of 16S rRNA gene). This suggests that among methanogenic archaea, Methanosarcina species which have different metabolic capabilities, including aceticlastic and hydrogenotrophic methanogenesis, were mainly involved in anaerobic digestion of turkey wastes.

• Journal of Microbiology and Biotechnology
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• 제27권7호
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• pp.1233-1241
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• 2017

The ginsenoside Rh2 has strong anti-cancer, anti-inflammatory, and anti-diabetic effects. However, the application of ginsenoside Rh2 is restricted because of the small amounts found in Korean white and red ginsengs. To enhance the production of ginsenoside Rh2-MIX (comprising 20(S)-Rh2, 20(R)-Rh2, Rk2, and Rh3 as a 10-g unit) with high specificity, yield, and purity, a new combination of enzymatic conversion using the commercial enzyme Viscozyme L followed by acid treatment was developed. Viscozyme L treatment at pH 5.0 and $50^{\circ}C$ was used initially to transform the major ginsenosides Rb1, Rb2, Rc, and Rd into ginsenoside F2, followed by acid-heat treatment using citric acid 2% (w/v) at pH 2.0 and $121^{\circ}C$ for 15 min. Scale-up production in a 10-L jar fermenter, using 60 g of the protopanaxadiol-type ginsenoside mixture from ginseng roots, produced 24 g of ginsenoside Rh2-MIX. Using 2 g of Rh2-MIX, 131 mg of 20(S)-Rh2, 58 mg of 20(R)-Rh2, 47 mg of Rk2, and 26 mg of Rh3 were obtained at over 98% chromatographic purity. Then, the anti-cancer effect of the four purified ginsenosides was investigated on B16F10, MDA-MB-231, and HuH-7 cell lines. As a result, these four rare ginsenosides markedly inhibited the growth of the cancer cell lines. These results suggested that rare ginsenoside Rh2-MIX could be exploited to prepare an anti-cancer supplement in the functional food and pharmaceutical industries.

• 한국분말야금학회:학술대회논문집
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• 한국분말야금학회 1994년도 춘계학술대회강연 및 발표대회 강연및 발표논문 초록집
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• pp.6-6
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• 1994

Har dmaterials such as cemented carbides with or without coated layer, cermets, ceramics and diamond or c-BN high pressure sintered compact are used for cutting tools, wear -resistant parts, rock drilling bits and/or high pressure vessels. These hardmaterials contain not only hard phase, but also second consituent as the element for forming ductile phase and/or sintering aid, and the mechanical properties of each material depend on (1) the amount of the second constituent as well as (2) the grain size of the hard phase. The hardness of each material mainly depends on these two factors. The fracture strength, however, largely depends on other microstructur a1 factors as well as the above two factors. For all hardmaterials, the fracture strength is consider ably affected by (3) the size of microstructur a1 defect which acts as the fracture source. In cemented carbides, the following factors which are generated mainly due to the addition of the second constituent are also important; (4) the variation of the carbon content in the normal phase region free from V-phase and graphite phase, (5) the precipitation of $Co_3$ during heating at about $800^{\circ}C$,(6) the domain size of binder phase, and (7) the formation of ${\beta}$-free layer or Co-rich layer near the surface of sintered compacts. For cemented carbides coated with thin hard substance, the important factors are as follows; (8) the kind of coated substance, (9) the formation of ${\eta}$-phase layer at the interface between coated layer and substrate, (10) the type of residual stress (tension or compression) in the coated layer which depends on the kind of coating method (CVD or PVD), and (11) the properties of the substrate, and (12) the combination, coherency and periodicity of multi-layers. In the lecture, the details of these factors and their effect on the strength will be explained.

• 한국식품영양과학회지
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• 제17권3호
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• pp.233-241
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• 1988

어육 단백질의 기능성을 개선하기 위해 정어리 분말단백질의 pepsin가수분해물을 이용하여 plastein을 합성하기 위한 반응조건을 검토하였다. plastein합성반응 최적조건으로서는 pepsin, ${\alpha}-chymotrypsin$, protease(from Aspergillus saitoi) 및 papain의 경우 PH는 각각 4, 7, 5 및 6, 기질농도는 pepsin과 ${\alpha}-chymotrypsin$의 경우 40%였으나 protease와 papain은 50%였다. 온도는 4종의 효소 모두가 $50^{\circ}C$였다. 기질의 가수분해도가 60%이상에서 plastin합성반응이 이루어졌으며, 가수분해도가 78.4% 이상이었을 때 plastein 생성량은 높았다.

• 한국인터넷방송통신학회논문지
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• 제12권1호
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• pp.165-172
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• 2012

$1.3{\mu}m$ 파장에서 동작하는 비대칭 Mach-Zehnder 간섭기에 분할전극 구조를 배열하여 전계 측정시스템의 감지부를 설계, 제작하였다. BPM 전산모사를 통해서 소자를 설계하였고, $LiNbO_3$에 Ti 확산방법으로 구현된 채널 광도파로에 집중 전극구조를 배열하여 집적광학 칩을 제작하였다. ${\pi}/2$ 위상차를 갖도록 설계된 비대칭 구조에서는 DC 0V에서 측정된 출력 광세기가 최고치에 약 1//2에 해당됨을 확인하였으며, 1KHz 전기신호를 인가해서 ${\pi}/2$ 위상차 때문에 나타나는 전기적 현상들을 확인하였다.

• IMMUNE NETWORK
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• 제11권1호
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• pp.50-58
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• 2011

Background: Epstein-Barr virus associated gastric lymphoepithelioma-like carcinoma (LELC) is characterized by the intensive infiltration of lymphoid cells, the presence of EBV, and the better prognosis over typical adenocarcinoma. Thus, it was assumable that viral latent proteins may be responsible for the recruitment of a certain T cell repertoire to EBV-associated gastric carcinoma. Methods: To examine above possibility, EBV gene expression in gastric carcinoma tissues and usage of TCR among the tumor infiltrating lymphocytes were analyzed. Results: EBV specific DNA and EBERs RNA were detected in 4 out of 30 patients. RT-PCR analysis revealed that all 4 of EBV-positive tumor tissues expressed EBNA1 mRNA and BARTs and LMP2a was detected only one sample out of 4. However, the EBNA2 and LMP-1 transcripts were not detected in these tissues. $CD8^+$ T cells were the predominant population of infiltrating lymphocytes in the EBV-positive gastric carcinoma. According to spectra type analysis of infiltrating T cells, 10 predominant bands were detected by TCR $V{\beta}$ CDR3 specific RT-PCR from 4 EBV-positive tumor tissues. Sequence analysis of these bands revealed oligoclonal expansion of T cells. Conclusion: These findings suggest that clonally expanded T cells in vivo might be a population of cytotoxic T cells reactive to EBV-associated gastric carcinoma.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2008년도 춘계 학술발표회 제20권1호
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• pp.925-928
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• 2008

최근 내진부재 및 기존 구조물의 내진보강요소의 손상제어(Damage tolerance)성능을 충족할 수 있는 변형경화형 시멘트 복합체(Strain-hardening cement composites, SHCC)의 개발 및 활용 연구가 진행 중이며, 하이브리드화에 따른 경제성 및 성능향상 가능성도 보고되고 있다. 그러나 이러한 우수한 성능을 갖는 SHCC 재료가 실구조물의 보수/보강재 및 내진보강부재에 적용되기 위해서는 우수한 인장성능 발현뿐만 아니라, 보강섬유의 단가를 고려한 경제적 효과(Economical efficiency) 및 시공성 (Workability)이 요구된다. 따라서 본 연구에서는 SHCC를 내진부재 및 보강재료로써 적용하기 위한 연구의 일환으로 합성섬유를 하이브리드하여 혼입시 휨 및 인장강도, 변형능력 등 거동특성을 분석함으로써 각 보강섬유의 인장강도 탄성계수 등 기계적 특성과 혼입율에 따른 재료성능과의 상관관계를 비교 분석하여 평가하고자 한다. 또한 물시멘트비를 변수로 하여 시멘트 복합체의 강도특성과 보강섬유의 부착특성 및 균열제어성능을 규명하고자 한다. 이러한 결과를 근거로 향후 SHCC 재료의 실구조물 적용시 요구성능 및 경제성을 고려한 재료배합에 관한 기초자료를 제시하고자 한다.