• 한국재료학회지
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• 제9권3호
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• pp.307-314
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• 1999

반응생성에 의한 Ti/TiB 복합재료를 제조하기 위한 반응분말$(TiB_2, B_4C)$, 소결온도, 소결시간을 결정하기 위하여 제조조건에 따른 반응생성상, 미세조직, 상대밀도 등을 조사하였다. 제조된 복합재료의 기계적 성질은 상온 압축항복강도로 평가하였다. 복합재료를 제조하기 위하여 혼합하는 $TiB_2$반응분말의 경우 $1300^{\circ}C, B_4C$ 반응분말의 경우 $1400^{\circ}C$의 소결온도가 최적조건임을 확인하였다. 본 공정에 의해서 제조된 복합재료의 압축항복강도는 비교재인 Ti-6Al-4V 보다 모두 우수하였다. 또한 $TiB_2$반응분말에 의해서 제조된 복합재료가 $B_4C$ 반응분말에 의해서 제조된 복합재료보다 우수한 압축항복강도를 나타내었다. 이는, 압축시험한 복합재료에서의 균열전파양상을 조사한 결과, 강화상과 기지간의 접합특성을 $B_4C$ 반응분말에 의한 복합재료의 접합특성보다 우수하였기 때문이었다.

• 한국재료학회지
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• 제2권3호
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• pp.207-212
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• 1992

과잉의 CaO와 $TiO_2$를 각각 포함한 $CaTiO_3$의 결함구조를 평형상태의 전기전도도를 $85O^{\circ}C$와 $1050^{\circ}C$사이에서 산소분압의 함수로 측정하여 연구하였다. 과잉의 CaO는 A site와 B site에 나누어져서 용해되어 $Ca_{Ti}$"와 Vo", 결함을 생성하였으며, 과잉의 $TiO_2$는 $V_{Ca}$"과 Vo"을 생성했다. 평형상태의 전기전도도는 CaO 용해도 5000ppm과 $TiO_2$ 용해도 2000ppm을 각각 나타냈다. 과잉의 양이온에 의하여 생성된 산소공공은 이온전도를 하여 넓은 영역의 산소 분압에 무관한 전도도 최소값을 보였으며, 반대로 대전된 음이온 결함과 결함쌍은 관찰되지 않았다.온 결함과 결함쌍은 관찰되지 않았다.

• 통상정보연구
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• 제5권2호
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• pp.3-17
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• 2003

This paper examined a e-Business utility of on-line shopping mall firms. Based on the literature review and cases study, the following results were found. First, in e-business policy, it was found that partnership between government and market are very important to e-business utility. Second, e-CRM of on-line shopping mall firms should be considered web site design based on commodity, cafe based on experience and information shares, and transaction confirm service. Third, B2C e-commerce model should be contained firm-specific force, customer oriented force, social force, and technology force.

• 한국재료학회지
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• 제9권9호
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• pp.943-947
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• 1999

$La(Mg_{1/2}Ti_{1/2})O_3$ 세라믹스의 구조 및 고주파 유전특성에 관한 연구를 하였다. $La(Mg_{1/2}Ti_{1/2})O_3$ 는 B site 양이온이 1:1 규칙화된 단사정 구조를 가지고 있었고 격자상수는 $a = 5.5467(3) {\AA}, b = 5.5616(3) {\AA}, c = 7.8426(5) {\AA} 그리고 \beta = 89.9589 (2)^{\circ}$ 로 밝혀졌고. $P2_1/n$의 공간군을 가지고 있었다. $La(Mg_{1/2}Ti_{1/2})O_3$ 내부에는 산소팔면체의 동상 및 역상 기울림이 존재하고 $a^_a^_c^_$ 기울림 구조를 가지고 있음을 알수 있었다. 또한 A site 양이온의 역 평행이동도 발견되었다. $1600^{\circ}C$ 이상에서 소결된 시료는 모두 95% 이상의 상대이론 밀도를 가지고 있었고 유전상수는 대략 28 정도였다. $1630^{\circ}C$ 에서 5시간 소결된 시료에서 최고높은 $Q\timesf_0$값, 63,000을 얻었다. LMT의 공진주파수 온도 계수는 $>-77 ppm/^{\circ}C ~ -79 ppm/^{\circ}C$였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2009년도 추계학술대회 논문집
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• pp.498-500
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• 2009

When we urgently need to develop and supply an alternative energy, wind power is growing with much interest because it has relative low cost for generating power and small area for wind turbine. To estimate the wind power resource, it is necessary to make an observation first. Although the large wind farm and resources are near coast and mountain area, the wind energy in urban area has the strong thing of direct access to power generator. In this study, we estimate the probability of wind energy in urban mountain area using A2C (Atmospheric to CFD) model, which is used for horizontally urban scale phenomena. In the steady state results, the site C is most suitable for wind power in the point of the only wind speed. But, estimating the TKE and vertical wind shear, the site B is showing the better results than the site C.

• Journal of Plant Biology
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• 제9권1_2호
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• pp.7-16
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• 1966

In order to determine the factors related to site quality, 13 areas of Larch growing in the Kwangung and its vicinity forest as sample plots, were examined. Sample plots included various site classes as well as age classes. Three were divided into two groups (major and minor trees). Average height of dominant trees was determined through messurement of 5 to 6 dominant tree in each sample plots. Average height of dominant 30 year-old trees was the basis for site index. A Standard Yield Table for the larch produced in Kwangnung forest was made by various data, which included age class 5, ranging from 10 to 45 years. The relationship of the height of the trees, the site conditions, and ground vegetation are investigated in this paper. The site indexes of 40 forest class age in 28-B and 28-G forest classes of the larch associations for ground vegetation had comparatively rarge differences due to the sampled areas. The relation of the direction of forest communities to the height and the diameter of the tree shwoed that its communiteis of northest and northwest parts appeared higher valueof the height and the diameter. The diameter and the height of trees were closely realted to each other. The samller the occupied area per tree and the smaller the average distance among trees, the more density was increased. The larger the density was the lower height of the trees. In the ground vegetation of the larch communities, there seems to be a definite correlation between the height of trees and the occupied area per tree or the average distance among the trees. The height of trees and site index of two larch communities were as follow: 28-B forest class site index 20.8, height 24.0m, 28-G forest class site index 18.4, height 20.9m. The ground layer was analyzed by the method of Quadrat(20/20sq. cm) with an interval of 1M. It set up 40 Quadrats of the larch communiteis. The community structure of the ground vegetation of two larch was analyzed, and important value was calculated and then evaluated. The ground vegetation under the larch had developed Burmannii Beauv stratal society below the 28-B and 28-G the forest class. Accordingly, the first important value of Burmannii Beauv was found in two ground vegetation below the larch. Therefore, this species could be quantitatively considered as the forest indicator species. Common species of each community appeared 18 species out of 34 species in the ground vegetation under two larch communities. The ground vegetation of the 28-B forest class showed more than that of the 28-G forest class. the similarity of the ground vegetation was measrued by the Frequency Index Community Coefficient. The differences between the associations were lcearly manifested by the ground vegetation tested by Gleason's Frequency Index of Community Coefficient for the analysis of each stratal society of all associations. According to F.I.C.C. the ground vegetation under two larch(28-B and 28-G) forest classes showed higher value. An investigation into the relationship of physical and chemical properties of soil and site was considered the next step to be taken in the study of the larch site classification.

• 생명과학회지
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• 제15권6호
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• pp.904-908
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• 2005

최근에 발표된 연구 결과에 의하면 pylori CagA내에 존재하는 SHP-2 binding site의 아미노산 서열을 분석한 후, 특정 서열이 위선암의 발병과 연관되어 있다고 보고하였다. 그러나 한국인을 대상으로 CagA 내 에 존재하는 SHP-2 binding site아미노산 서열의 특성을 밝힌 연구는 없다. 따라서 본 연구는 한국인에서 획득한 H. pylori의 CagA SHP-2 binding site에 대해 아미노산 서열을 분석하여 그 특성을 알아보고자 하였다. 총 62 균주의 H. pylori 를 분석한 결과 환자의 질환과 관계없이 모든 H. pylori 균주에서 East Asian (A-B상 혹은 A-B-B-D)을 보여주었다. 일본과 더불어 한국은 위선암 유병률이 높은 나라이므로, 연구 대상의 모든 한국인에서 East Asian type CagA를 가진 H. pylori가 발견된 것이 위선암 유병률과 연관될 가능이 높아 보인다. 그러나 H. pylori의 발병 기전을 보다 더 명확히 이해하기 위해서는 보다 많은 국가와 지역을 대상으로 이러한 유전형 조사가 필요할 것 같다.

• Bulletin of the Korean Chemical Society
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• 제26권2호
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• pp.285-291
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• 2005

The nonstructural protein 5B (NS5B) of hepatitis C virus (HCV) is the viral RNA-dependent RNA polymerase (RdRp), which is the essential catalytic enzyme for the viral replication and is an appealing target for the development of new therapeutic agents against HCV infection. A small amount of serum from a single patient with hepatitis C was used to get the genome of a Korean HCV isolate. Sequence analysis of NS5B 1701 nucleotides showed the genotype of a Korean isolate to be subtype 1b. The soluble recombinant HCV NS5B polymerase lacking the C-terminal 24 amino acids was expressed and purified to homogeneity. With the highly purified NS5B protein, we established in vitro systems for RdRp activity to identify potential polymerase inhibitors. The rhodanine family compounds were found to be potent and specific inhibitors of NS5B from high throughput screening (HTS) assay utilizing the scintillation proximity assay (SPA) system. The binding mode of an inhibitor was analyzed by measuring various kinetic parameters. Lineweaver-Burk plots of the inhibitor suggested it binds not to the active site of NS5B polymerase, but to an allosteric site of the enzyme. The activity of NS5B in in vitro polymerase reactions with homopolymeric RNA requires interaction with multiple substrates that include a template/primer and ribonucleotide triphosphate. Steady-state kinetic parameter, such as Km, was determined for the ribonucleotide triphosphate. One of compounds found interacts directly with the viral polymerase and inhibits RNA synthesis in a manner noncompetitively with respect to UTP. Furthermore, we also investigated the ability of the compound to inhibit NS5B-directed viral RNA replication using the Huh7 cell-based HCV replicon system. The investigation is potentially very useful for the utility of such compounds as anti-hepatitic agents.

• Molecules and Cells
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• 제26권2호
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• pp.212-215
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• 2008

The GC-rich discriminator sequence between the -10 region and the transcription start site of the rnpB promoter is responsible for stringent control of M1 RNA synthesis. The rnpB promoter also contains a G nucleotide at the previously identified transcription start site. In this study, we examined by mutagenesis of G to A whether this +1G nucleotide is involved in the stringent response. We found that the change did not alter the stringent response. Since the +1 mutation might alter transcription initiation, we compared the transcription start sites of the wt and mutant promoters by primer extension analysis. Surprisingly, we found that wild type rnpB transcription starts at both the +1G position (70%) and the -1C position (30%), and that the +1A mutation led to transcription initiation exclusively at the -1C position. We also generated two transversion mutations at the -1 position, both of which led to transcription starting exclusively at that position. The -1G mutant promoter gave a stringent signal similar to the wild-type, whereas the -1A mutant generated a significantly less stringent signal. Base on these results, we propose that a short sequence, up to 7 bp downstream of the -10 region, is involved in the stringent response of the rnpB promoter.

• 한국세라믹학회지
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• 제40권1호
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• pp.37-45
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• 2003

$BaTiO_3$의 Ba 자리에 Ca, Ti 자리에 Zr을 첨가한 $(B a_{1-x}Ca_x)(Ti_{0.96-y}Zr_{y}Sn_{0.04})O_3$ $(0.15 {\leq} x{\leq}0.20,\; 0.09{\leq}y{\leq}$0.14) 조성에 2차상 형성을 유도하여 복합체를 만든 후 유전 및 소결 특성을 조사하였다. Ca량이 15mol% 이상 첨가됨에 따라 $CaTiO_3$를 주성분으로 하는 2차상이 석출하여 복합체가 형성되었으며, Ca량의 증가에 따라 2차상 분율이 증가하였다. Ca량의 증가는 큐리 온도를 mol%당 $1.7^{\circ}C$ 감소시키며, 저유전율 2차상의 영향으로 Ca량 증가에 따라 최대 유전율은 mol%당 200 감소하였다. Zr 첨가는 큐리온도를 mol%당 $10^{\circ}C$ 감소시키며, 확산형 상전이 현상을 증가시켜 최대 유전율을 217 감소시켰다. 2차상의 증가에 의하여 비정상 입성장이 억제되어 소결밀도, 내전압 특성이 향상되었으며, Zr 첨가에 의하여 커패시턴스의 온도 안정성을 제어하여 EIA 규격을 만족하는 고압, 고유전율 Y5U 콘덴서 조성을 개발하였다.