• 한국재료학회지
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• 제12권4호
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• pp.317-323
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• 2002

Effect of V and Sb content on characteristics of ${\beta}\;to\;{\alpha}$ phase transformation in Zr-0.84Sn alloy has been studied using optical microscopy and transmission electron microscopy. As V content increased, the ${\beta}{\to}{\beta}+{\alpha}$ transformation temperature was lowered, thus allowing the width of $\alpha$-lath in air-cooled Zr-0.86Sn-0.40V alloy to be fine. The width of ${\alpha}$-lath in air-cooled Zr-0.84Sn-xSb, however, was rarely changed with Sb content. The ${\beta}\;to\;{\alpha}$ transformed microstructures of water-quenched Zr-0.84Sn, Zr-0.84Sn-0.10V and Zr-0.84Sn-0.19V alloys were mainly slipped martensite. On the other hand, those of wafter-quenched Zr-0.86Sn-0.40V and Zr-0.85Sn-0.05Sb alloys were predominantly twinned martensite. In case of water-quenched Zr-0.85Sn-0.12Sb and Zr-0.84Sn-0.17Sb alloys, basketweave structure was observed. The transition of slipped martensite to twinned martensite in Zr-0.84Sn-xV alloys and the transition of twinned martensite to basketweave structure in Zr-0.84Sn-xSb alloys were due to the decrease of $M_s$ temperature.

• 열처리공학회지
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• 제23권5호
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• pp.233-238
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• 2010

The phase transformations and the shape memory effect in In-rich Pb alloys and In rich-Sn alloys have been studied by means of X-ray diffractometry supplemented by metallographic observations. The alloys containing 12~15 at.%Pb transform from the ${\alpha}_2$ (fct) phase to the ${\alpha}_1$ (fct) phase by way of an intermediate phase (m phase) on cooling. The results of X-ray diffraction show that the metastable intermediate phase is observed both on cooling and heating, and has a face-centered orthorhombic (fco) structure. It is concluded that the ${\alpha}_1{\rightleftarrows}{\alpha}_2$ transformation is expressed by the ${\alpha}_1{\rightleftarrows}m{\rightleftarrows}{\alpha}_2$ transformation both on usual cooling and heating with the rate more than $8{\times}10^{-3}$ K/s. The $m{\rightleftarrows}{\alpha}_2$ transformation takes place with a mechanism involving macroscopic shear and are of diffusionless (martensitic) type. The temperature hysteresis in the two transformations is 10~13 K between the heating and cooling transformations. The alloys containing 0~11 at.%Sn are -phase solid solutions with a face centered tetragonal structure (c/a > 1) at room temperature, the axial ratio increasing continuously with tin content. The In-(11~15) at.%Sn alloys are mixtures of ${\alpha}$ and ${\beta}$ phases, the ${\beta}$ phase having a f. c. tetragonal structure (c/a < 1). The alloys containing more than 15 at.%Sn are ${\beta}$-phase solid solutions. The In-(12.9~15.0) at.%Sn alloys show a shape memory effect only when quenched to the temperature of liquid nitrogen, although their effect becomes weak and finally disappears after keeping at room temperature for a long time. The ${\beta}{\rightarrow}{\alpha}^{\prime}$ phase transformation is of the diffusionless (martensitic) type, and takes place between 330 K at 12.9 at.%Sn and 150 K at 14.5 at.%Sn. The hysteresis of transformation temperatures on heating and cooling is considerably large (29~40 K), depending on the composition. Both In-Pb and In-Sn alloys showed distinct the shape memory effects.

• 한국세라믹학회지
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• 제32권12호
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• pp.1417-1423
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• 1995

α/β sialon based composites containing silicon nitride whisker and silicon carbide platelet were fabricated by hot pressing. Effect of the reinforcing agents on the α to β phase transformation of the sialon as well as on the mechanical properties was investigated. Silicon nitride whisker and silicon carbide platelet promoted the phse transformation. TEM/EDS analysis revealed that the grain containing the whisker had 'core-rim' structure; core being high purity Si3N4 whisker and rim being β-sialon. Flexural strength of the composite decreased with the reinforcement addition which, on the other hand, improved fracture toughness of it. High temperature strength was measured at 1300℃ to be about 130 MPa lower than that measured at RT for the whisker reinforced composites.

• 열처리공학회지
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• 제16권2호
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• pp.90-96
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• 2003

The effect of betatizing temperature on microstructure and transformation characteristics in a Cu-AI-Ni based pseudoelastic alloy fabricated by heated mold continuous casting by using metallography, XRD and calorimetry. The microstructure of cast rod betatized at $600^{\circ}C$ revealed a ${\beta}_1$ parent phase and a ${\gamma}_2$ phase precipitated along the casting direction. When the cast rod was betatized at the elevated temperature above $600^{\circ}C$, the ${\gamma}_2$ phase is completely dissolved into the matrix so that the volume fraction of the ${\gamma}_2$ phase was decreased. The parent phase was stabilized by betatizing at $600^{\circ}C$. However, the ${\beta}_1$ parent phase was transformed to both ${{\beta}_1}^{\prime}$ and ${{\gamma}_1}^{\prime}$ martensites with increasing betatizing temperatures above $600^{\circ}C$, while $M_s$ and $A_s$ temperatures were decreased. The stress-strain curves for compression test were not same with betatizing temperature; the stress-strain curves of the specimen betatized at $600^{\circ}C$ and $700^{\circ}C$ were linear but those of the specimen betatized at $800^{\circ}C$ and $900^{\circ}C$ were not linear.

• Current Research on Agriculture and Life Sciences
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• 제11권
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• pp.11-17
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• 1993

완두에 있어서 보다 효율적인 형질전환 방법을 모색하고 형질전환된 개체를 얻고자 본 실험을 수행하여 얻어진 결과는 다음과 같다. 형질전환은 발아중인 완두의 생장점(shoot tip)을 제거한 다음 T-DNA내에 GUS gene과 neomycin phosphotransferase II gene이 들어있는 binary vector를 가진 Agrobacterium tumefaciens를 생장점을 제거한 부위에 감염시켰다. 감염 후 새로 형성된 shoot는 개체당 4~5개였으며, 그중 GUS유전자가 발현하는 shoot만을 정상적인 식물체로 분화 시켰다. 감염부위에서 형성된 shoot에서의 GUS유전자의 발현빈도는 10%내외였다. 이들 개체로 부터 genomic DNA를 분리하여 Dot blot hybridization분석 결과 T-DNA가 식물체 내에 존재함을 알 수 있었고, 수확한 종자를 발아시켜 Sorthern blot hybridization한 결과 T-DNA가 다음세대로 전달되었음이 확인되었으며 형질전환율은 2%이내였다.

• 한국분말재료학회지
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• 제20권3호
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• pp.210-214
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• 2013

This manuscript reports on compared color evolution about phase transformation of ${\alpha}-FeOOH@SiO_2$ and ${\beta}-FeOOH@SiO_2$ pigments. Prepared ${\alpha}$-FeOOH and ${\beta}$-FeOOH were coated with silica for enhancing thermal properties and coloration of both samples. To study phase and color of ${\alpha}$-FeOOH and ${\beta}$-FeOOH, we prepared nano sized iron oxide hydroxide pigments which were coated with $SiO_2$ using tetraethylorthosilicate and cetyltrimethyl-ammonium bromide as a surface modifier. The silica-coated both samples were calcined at high temperatures (300, 700 and $1000^{\circ}C$) and characterized by scanning electron microscopy, CIE $L^*a^*b^*$ color parameter measurements, transmission electron microscopy and UV-vis spectroscopy. The yellow ${\alpha}$-FeOOH and ${\beta}$-FeOOH was transformed to ${\alpha}-Fe_2O_3$ with red, brown at 300, $700^{\circ}C$, respectively.

• The Korean Journal of Ceramics
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• 제1권1호
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• pp.45-54
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• 1995

Four kinds of silicon nitride based ceramic materials have been hot pressed. Effect of the sintering additives on the phase transformation, microstructural development and mechanical properties was investigated. While sintering under the same condition a big difference among the microstructures of the specimens, they appeared alike if sintered to have a similiar $\alpha$-$\beta$ phase ratio. The specimen of the stoichiometric $\alpha$-$\beta$ sialon composition showed very limited amount of the intergranular glassy phase and a significant degree of the residual stress. It exhibited almost no strength degradation up to $1300^{\circ}C$, and the strength of the specimen degraded more as its composition deviated from the stoichiometry.

• Asian-Australasian Journal of Animal Sciences
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• 제6권4호
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• pp.581-589
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• 1993

A plasmid vector, $RSVLTR/{\beta}G2$, containing lacZ gene under the control of the RSVLTR promoter were transfected into chicken embryo fibroblasts by three different transfection methods. Calcium phosphate, lipsome and DEAE-dextran techniques were applied for transfection of chicken cells. A histochemical assay with X-gal was used as a simple method for screening transfected cells. Plasmid $RSVLTR/{\beta}G2$ was expressed proficiently in the chicken embryo fibroblast. Calcium phosphate-DNA precipitate transfection resulted in the highest efficiency for transient expression of $RSVLTR/{\beta}G2$. Transfected cells formed colonies on the 9th day of incubation indicating stable transformation of the inserted plasmid.

• East Asian mathematical journal
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• 제31권1호
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• pp.103-107
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• 2015

We use some known contiguous function relations for $_2F_1$ to show how simply the following three recurrence relations for Jacobi polynomials $P_n^{({\alpha},{\beta)}(x)$: (i) $({\alpha}+{\beta}+n)P_n^{({\alpha},{\beta})}(x)=({\beta}+n)P_n^{({\alpha},{\beta}-1)}(x)+({\alpha}+n)P_n^{({\alpha}-1,{\beta})}(x);$ (ii) $2P_n^{({\alpha},{\beta})}(x)=(1+x)P_n^{({\alpha},{\beta}+1)}(x)+(1-x)P_n^{({\alpha}+1,{\beta})}(x);$ (iii) $P_{n-1}^{({\alpha},{\beta})}(x)=P_n^{({\alpha},{\beta}-1)}(x)+P_n^{({\alpha}-1,{\beta})}(x)$ can be established.

• 약학회지
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• 제37권6호
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• pp.555-560
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• 1993

Methyl 3-[(phenylsulfonyl)methyl]-1, 4, 8-trimethoxy-2-naphthoate(7) preparad by 3 steps was condensed with 5-ethyl-2-cyclohexen-1-one(8) to afford the teracyclic aromatic ring system compound 10, which was stepwise converted into the precursor of 11-Deoxy-$\beta$-rhodomycinone by means of various functional groups transformation.