• 한국미생물·생명공학회지
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• 제32권2호
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• pp.128-134
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• 2004

가정에서 제조된 된장으로부터 -galactosidase의 생산균으로 분리된 YB-42는 형태적 특성, 생화학적 성질 및 16S rRNA의 염기서열에 근거하여 Bacillus licheniformis로 동정되었다. B. lichentyormiE YB-42의 -galactosidase 활성은 균체내ㆍ외에서 모두 관찰되었다. 배양상등액으로부터 DEAE-Sepharose와 Q-Sepharose 컬럼 크로마토그래피를 통해 부분 정제한 -galactosidase을 사용하여 para-nitrophenyl--D-galactopyranoside(pNP-Gal)의 가수분해 반응특성을 조사한 결과 와 pH 6.5에 서 최대 활성을 보였다. Melibiose, raffinose와 stachyose는 부분 정제효소액에 의해 완전히 가수분해 되었으며, 분해산물로 galactose가 생성된 것으로 보아 -1,6 결합이 분해된다는 것이 확인되었다. 한편 pNP-Gal과 melibiose의 가수분해 활성은 galactose에 의해 가장 크게 저해되었으며, galactose보다는 낮지만 pNP-Gal의 가수분해 활성이 mannose와 glucose에 의해서도 저해되는 것으로 나타났다.

• Journal of Welding and Joining
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• 제31권3호
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• pp.31-38
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• 2013

The transition of serrated grain boundary and its effect on liquation behavior in the simulated weld heat-affected zone (HAZ) have been investigated in a wrought Ni-based superalloy Alloy 263. Recently, the present authors have found that grain boundary serration occurs in the absence of adjacent coarse ${\gamma}^{\prime}$ particles or $M_{23}C_6$ carbides when a specimen is direct-aged with a combination of slow cooling from solution treatment temperature to aging temperature. The present study was initiated to determine the interdependence of the serration and HAZ property with a consideration of this serration as a potential for the use of a hot-cracking resistant microstructure. A crystallographic study indicated that the serration led to a change in grain boundary character as special boundary with a lower interfacial energy as those terminated by low-index {111} boundary planes. It was found that the serrated grain boundaries are highly resistant to boron enrichment, and suppress effectively grain coarsening in HAZ. Furthermore, the serrated grain boundaries showed a higher resistance to susceptibility of liquation cracking. These results was discussed in terms of a significant decrease in interfacial energy of grain boundary by the serration.

• 대한한의학회지
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• 제20권1호
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• pp.11-21
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• 1999

Dansam, the root of Salvia miltiorrhiza BGE. (Labiatae), has a bitter and a slightly 'cold' property. and is nontoxic. It has been used for the treatment of diseases such as tumors, bruises, gynecologic diseases, menoxenia, anemia and so forth. As an oriental medicine pathway, anal therapy has many kinds of treatments, Retention enema is one the most useful, advantageous methods of anal therapy. This experiment was performed in order to study the effect of an aqueous extract of Salviae radix root(SRRAE) on Immediate type allergic reaction by Retention enema. The results were obtained as follows, 1. SRRAE inhibited compound 48/80-induced Immediate type allergic reaction 100% with the dose of 0.1g/kg by anal treatment. However, SRRAE showed no significant inhibitory effect on the same reaction by oral treatment. When mice were pretreated with SRRAE at a concentration ranging from 0.001 to 1.0g/kg, by intra-anal treatment, the serum histamine levels were reduced in a dose-dependent manner. 2. SRRAE also inhibited by 79.8% local cutaneous allergic reaction activated by anti-dinitrophenyl (DNP) IgE. 3. SRRAE close-dependently inhibited the histamine release from rat peritoneal mast cells(RPMC) by anti-DNP IgE., but SRRAE not inhibited compound 48/80-induced histamine release. 4. SRRAE dose-dependently inhibited tumor necrosis $factor-\;{\alpha}$ $(TNF-\;{\alpha}$) production from RPMC by anti-DNP IgE. Moreover, the level of cAMP in RPMC, when SRRAE was added, significantly increased compared with that of a normal control. According to the above results, anal therapy(Retention enema) of SRRAE may be beneficial in the treatment of systemic and local Immediate type allergic reactions.

• 한국정보시스템학회지:정보시스템연구
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• 제15권1호
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• pp.1-20
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• 2006

Peer-to-peer systems (P2P) are rapidly growing in importance on the Internet environment, quickly extending the range of their usage. However, peer-to-peer systems have not been widely applied in electronic commerce because they have not been established as an appropriate business model. Therefore, we firstly review the previous research relevant to peer-to-peer systems, and then analyze the business models for P2P systems presented by previous researchers. Furthermore, this study categorizes major issues in terms of the technical and business model aspects. On the basis of these reviews, we develop P2P electronic commerce systems based on the file sharing method between users, focusing on user interface friendliness. A developed P2P electronic commerce systems are programmed by using the C# based on the Microsoft.net solution. A database is implemented using the MSSQL2000. A main application technology is designed that P2P electronic commerce systems make it possible. for user to extend into BtoB Solution by using WSDL (Web Services Description Language), UDDI (Universal Description, Discovery, and Integration) and the XML that is a document for users. User interface is made as form of Internet messenger for a user's convenience and is possible to develop into a commodity transaction system based on XML. In this study, it is possible for the P2P electronic commerce system to have extended application to fields such as Internet shopping mall and property transaction in a nonprofit organization, a public institution and a large scale nonprofit institution that have a similar structure as compared with a structure of a nonprofit educational institution.

• 한국건축시공학회지
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• 제17권1호
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• pp.55-61
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• 2017

본 연구는 국내 레디믹스트 콘크리트 제조 시 57골재(5~25mm)의 경우 7번 입자(5~13mm)가 갭그레이딩되어 문제시 되는 것을 13mm 이하 RCA로 보충 해결하고자 하는 것이다. 실험 결과, 기존 레디믹스트 콘크리트용 57골재에 13mm 이하 RCA를 30%정도 혼합하여 30MPa급 콘크리트에 사용할 경우 연속입도 구현에 따른 유동성의 향상, 배합상 단위수량과 잔골재율의 감소가 가능해 압축강도를 향상시키며 건조수축을 저감시킬 수 있을 것으로 판단된다.

• 한국세라믹학회지
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• 제37권4호
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• pp.354-358
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• 2000

Tetragonal (t)-ZrO2/Al2O3 composites doped with Y2O3, Nb2O5, and Fe2O3 ((Y, Nb, Fe)-TZP/Al2O3) were prepared over the range containing Fe2O3 from 0.1 to 0.5 mol% with 0.1 mol% intervals to evaluate the effect of Fe2O3 addition on chromaticity, hydrothermal stability, and mechanical property of the composites. After autoclaving for 20 h at 18$0^{\circ}C$ under 3.5 MPa water vapor pressure, no tlongrightarrowm phase transformation was observed probably due to the preferential solid solubility of Fe2O3 in Al2O3, the presence of the rigid Al2O3 particles, and the inherent phase stability of (Y, Nb)-TZP. The optimized strength and the fracture toughness of the composite were 700 MPa and 8.5 MPa.m1/2, respectively, when 0.1 mol% Fe2O3 was added. The composites have shown a gradual color change from a slightly white ivory to a pale yellowish brown with increasing the Fe2O3 concentration.

• 한국세라믹학회지
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• 제48권5호
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• pp.447-453
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• 2011

The monodisperse spherical $SiO_2$ particles were overcoated with $Y_2O_3:Eu^{3+}$ phosphor layers via a Pechini sol-gel process and the resulting $SiO_2@Y_2O_3:Eu^{3+}$ core-shell phosphors were subsequently annealed at $800^{\circ}C$ at an ambient atmosphere. The crystallographic structure, morphology, and luminescent property of core-shell structured $SiO_2@Y_2O_3:Eu^{3+}$ phosphors were characterized by X-ray diffraction (XRD), field emission scanning electron microscopy (FE-SEM), and photoluminescence (PL). The spherical, nonagglomerated $SiO_2$ particles prepared by a Stober method exhibited a relatively narrow size distribution in the range of 260-300 nm. The thickness of phosphor shell layer in the core-shell particles can be facilely controlled by varying the coating number of $Y_2O_3:Eu^{3+}$ phosphors. The core-shell structured $SiO_2@Y_2O_3:Eu^{3+}$ phosphors showed a strong red emission, which was dominated by the $^5D_0-^7F_2$ transition (610 nm) of $Eu^{3+}$ ion under the ultraviolet excitation (263 nm). The PL emission properties of $SiO_2@Y_2O_3:Eu^{3+}$ phosphors were also compared with pure $Y_2O_3:Eu^{3+}$ nanophosphors.

• 한국재료학회지
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• 제22권10호
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• pp.504-507
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• 2012

Synthesis of RGO (reduced graphene oxide)-CdS composite material was performed through CBD (chemical bath deposition) method in which graphene oxide served as the support and Cadmium Sulfate Hydrate as the starting material. Graphene-based semiconductor photocatalysts have attracted extensive attention due to their usefulness for environmental and energy applications. The band gap (2.4 eV) of CdS corresponds well with the spectrum of sunlight because the crystalline phase, size, morphology, specic surface area and defects, etc., of CdS can affect its photocatalytic activity. The specific surface structure (morphology) of the photocatalyst can be effective for the suppression of recombination between photogenerated electrons and holes. Graphene (GN) has unique properties such as a high value of Young's modulus, large theoretical specific surface area, excellent thermal conductivity, high mobility of charge carriers, and good optical transmittance. These excellent properties make GN an ideal building block in nanocomposites. It can act as an excellent electron-acceptor/transport material. Therefore, the morphology, structural characterization and crystal structure were observed using various analytical tools, such as X-ray diffraction, scanning electron microscopy, transmission electron microscopy, and Raman spectroscopy. From this analysis, it is shown that CdS particles were well dispersed uniformly in the RGO sheet. Furthermore, the photocatalytic property of the resulting RGO-CdS composite is also discussed in relation to environmental applications such as the photocatalytic degradation of pollutants. It was found that the prepared RGO-CdS nanocomposites exhibited enhanced photocatalytic activity as compared with that of CdS nanoparticles. Therefore, better efficiency of photodegradation was found for water purification applications using RGO-CdS composite.

• 한국식품조리과학회지
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• 제30권6호
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• pp.716-725
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• 2014

Gelatinization properties and the molecular structure of Korean waxy rice starchesisolated from two japonica types, Sinseonchal, and Dongjinchal, as well as an indica type, Hangangchal 1 were investigated. Sinseonchal is preferred cultivar for making Korean traditional rice cakes and cookies. Sinseonchal starch was the highest in crude protein, amylopectin, damaged starch contents, and water binding capacity among the cultivars tested. The initial pasting temperature ($72.75^{\circ}C$), peak (360.54 RVU), breakdown (162.21 RVU) and setback (30.83 RVU) viscosities of Sinseonchal had the highest values (p<0.05). Onset and peak temperatures by differential scanning calorimeter were also the highest in Sinseonchal. The molecular weight of Sinseonchal amylopectin was 5.46 107higher than those of the other cultivars, but its peak height and area were the lowest among them. The amylopectin peak by HPSEC showed a shoulder in the lower molecular weight portion and its relative area decreased in the following order; Sinseonchal > Dongjinchal > Hangangchal 1. On the branch chain length distribution of amylopectin, the proportion of DP13-24 and DP25-36 showed reverse trends, with higher japonica type amylopectin in DP13-24.

• 대한금속재료학회지
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• 제48권1호
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• pp.28-38
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• 2010

High temperature high cycle and low cycle fatigue deformation behavior of automotive heat resistant aluminum alloys (A356 and A319 based) were investigated in this study. The microstructures of both alloys were composed of primary Al-Si dendrite and eutectic Si phase. However, the size and distribution for eutectic Si phase varied: a coarse and inhomogeneous distributed was observed in alloy B (A319 based). A brittle intermethallic phase of ${\alpha}-Fe\;Al_{12}(Fe,Mn)_3Si_2$ was detected only in B alloy. Alloy B exhibited high fatigue life only under a high stress amplitued condition in the high cycle fatigue results, whereas alloy A showed high fatigue life when stress was lowered. With regard to the low-cycle fatigue result ($250^{\circ}C$) showing higher fatigue life as ductility increased, alloy A demonstrated higher fatigue life under all of the strain amplitude conditions. Fractographic observations showed that large porosities and pores near the outside surface could be the main factor in the formation of fatigue cracks. In alloy B. micro-cracks were formed in both the brittle intermetallic and coarse Si phasese. These micro-cracks then coalesced together and provided a path for fatigue crack propagation. From the observation of the differences in microstructure and fractography of these two automotive alloys, the authors attempt to explain the high-temperature fatigue deformation behavior of heat resistant aluminum alloys.