• 한국재료학회지
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• 제11권8호
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• pp.664-664
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• 2001

$\sigma$-VFe 금속간화합물에 대한 기계적 합금화(MA) 효과를 중성자 및 X선 회절법으로 조사하였다. MA 분말의 구조분석은 X선 회절(Cu-K$\alpha$) 린 중성자회절(HRPD, λ=1.835$\AA$)을 이용하여 행하였다. $\sigma$-VFe화합물의 MA시 큰 구조변화가 관찰되었으며, MA 60시간의 경우 Fe-Fe 훤자분포는 unit cell에 30개의 원자를 포함하고 있는 $\sigma$상의 tetragonal구조에서 $120^{\circ}C$이상에서 안정하게 존재하는 $\alpha$-(V,Fe) 고용체의 bcc 구조로 상변화함을 알 수 있었다. 또한 $\alpha$-VFe 화합물에 대한 중성자 및 X선 회절패턴의 비교분석을 행하였으며 그 결과 $\sigma$상이 가지는 화학적 규칙성에 기인하는 (101)과 (111) 회절 피크가 중성자 회절에서 뚜렷하게 관찰됨을 알 수 있었다.

• 자원리싸이클링
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• 제3권3호
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• pp.21-26
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• 1994

국내에서 산출되고 있는 반토혈암으로부터 고순도 $\alpha-Al_2O_3$를 얻기 위하여 황산암모늄을 사용한 염배소와 황산을 이용한 추출 그리고 하소 실험을 하였다. 황산의 농도, 반응시간, 온도 등이 알루미나 추출에 미치는 영향에 대하여 조사하였으며, 반응산물은 X-ray, DTA-TG, 화학분석, SEM 등으로 분석하였다. 추출조건은 전처리 조건으로 황산암모늄의 농도가 0.6M, 배소온도가 $650^{\circ}C$였으며, 황산추출은 황산농도 10%로 240분간 추출할 경우 96%의 수율을 나타내었다. 생성된 $Al_2O_3$ 분말을 X-ray 분석한 결과 $\alpha-Al_2O_3$였으며 그 순도는 99.23%였다.

• 한국환경보건학회지
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• 제29권4호
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• pp.48-54
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• 2003

This study investigated retrogradation properties of Jeungpyun substituted for cereals with dietary fibers of 60% of brown rice, and barley. Quality changes during storage periods of the functional Jeungpyun, were studied using $\alpha$-amylase iodine enzyme digestion methods, X-ray diffraction patterns, and differential scanning calorimetry (DSC). The barley substituted samples showed significantly lower retrogrdation rates than those of control when examined by $\alpha$-amylase method. The Relative crystallity by X-ray diffraction patterns had typical A type in all samples with appealing big crystallity around its diffraction angle 23$^{\circ}$degrees as storage periods were increased. The brown rice and barley Jeunpyun made smaller crystallity than that of control, representing slower retrogradation rates. The batter controls had significantly lower ΔH than the other compared samples when measured by DSC, but had significantly higher ΔH after 30 days of storage, implying that the control required more energy for regelatinization after the 30 days of storage.

• Journal of the Korean Physical Society
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• 제73권12호
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• pp.1834-1839
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• 2018

A tabletop ultrafast soft x-ray has been generated from the laser-produce plasma with a femtosecond pulsed Ti:Sapphire laser. The estimated total flux of Al $K{\alpha}$ is of $2.2{\times}10^9photons/sec$ in $4{\pi}$ radian and the parameters related to the optical performance were obtained. The tungsten/silicon multilayer, flat quartz and bent thallium acid phthalate (TLAP) crystal were used for monochromatization of soft x-ray to refine the aluminum $K{\alpha}$ radiation and compared the respective value of $E/{\Delta}E$. To estimate the size of the x-ray source beam generated by a fs laser, the approximation using the FWHM obtained from the x-ray beam scan near the focal point was discussed, and the size of the diameter was about $9.76{\mu}m$.

• 한국해양공학회지
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• 제8권1호
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• pp.114-122
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• 1994

X-ray stress constant, K, was determined for the diffraction line of (211)plane by using Cr-K$\alpha$ radiation. K was -340.87 MPa/deg. Fatigue crack propagation tests of SS41 steel were conducted under stress ratios of 0.1, 0.3 and 0.5. The half-value breadth of X-ray diffraction profile was measured at and beneath the fracture surface. The half-value breadth, B, on the fracture surface was found to increase with increasing $K_max$. The value of B was influenced by stress ratio in SS41 steel. The half-value breadth took the maximum value at the borden of reversed plastic zone, while it approached to the initial (pre-fatigue) value near the boundary of monotonic plastic zone. The maximum depth of the plasticzone was evaluated on the basis of the half-value breadth distribution. The depth $\omega$$_y$ is related to $K_max$by the following equation : $\omega$$_y$ = $\alpha$($K_max$/$\sigma$$_y$$)^2$ where .sigma.$\sigma$$_y$ is the yield strength obtength obtained in tension test .alpha.is 0.136 for SS41 steel.

• Macromolecular Research
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• 제13권2호
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• pp.156-161
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• 2005

The thermal transitions of a nylon 6/layered silicate nanocomposite were studied by differential scanning calorimetry and in-situ synchrotron X-ray diffraction. The drawn film of the nylon 6/layered silicate nanocomposite typically showed three endotherms in the DSC thermogram; a very broad endotherm at $\sim120^{\circ}C(T_{1})$, a double-melting endotherm at $\sim215^{\circ}C(T_{2})$, and a high temperature endotherm at $\sim240^{\circ}C(T_{3})$. The drawn film of the nylon 6/ layered silicate nanocomposite was comprised of a mixture of the $\alpha and \gamma$ forms, with $the \alpha form$ being generated by drawing the pressed film having $the \gamma form$. The melting and crystallization of the crystals were observed at the above thermal transitions during the heating experiment performed at the Pohang X-ray synchrotron radiation source (4C2). The newly generated form was meta-stable and melted $at {\sim}T_{1}$. The double-melting $at {\sim}T_{2}$ was due to the exothermic crystallization of $the \alpha form$ during the main endothermic melting of $the \gamma form$. $The \alpha form$ crystallized $at {\sim}T_{2}$ and melted $at {\sim}T_{3}$.

• 한국진공학회지
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• 제17권3호
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• pp.247-252
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• 2008

휴대용 XRF(X-Ray Fluorescence) 장치에 적용하기 위하여 개발한 투과 양극형 x-ray tube를 이용하여 XRF 실험을 하고, x-ray tube가 XRF data에 미치는 영향을 조사하였다. W-target tube와 Rh-target tube를 이용하여 측정한 XRF data는 알려진 결과와 잘 일치하였다. 35 kV와 관전압과 $40{\mu}A$의 관전류에서 W-target tube로 측정한 Fe $K_{\alpha}$-line의 FWHM은 약 180 eV로써, 이 값은 물질의 성분분석을 하기에 충분한 것으로 확인하였다. XRF data와 x-ray tube의 적분강도 곡선을 비교 분석해 본 결과, 휴대용 XRF 장치에는 W-Target tube보다는 Rh-Target tube를 사용하는 것이 더 유리함을 밝혀내었다.

• Molecules and Cells
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• 제19권2호
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• pp.219-222
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• 2005

The a-subunit of Escherichia coli tryptophan synthase (${\alpha}TS$), a component of the tryptophan synthase ${\alpha}_2{\beta}_2$ complex, is a monomeric 268-residues protein (Mr = 28,600). ${\alpha}TS$ by itself catalyzes the cleavage of indole-3-glycerol phosphate to glyceraldehyde-3-phosphate and indole, which is converted to tryptophan in tryptophan biosynthesis. Wild-type and P28L/Y173F double mutant ${\alpha}$-subunits were overexpressed in E. coli and crystallized at 298 K by the hanging-drop vapor-diffusion method. X-ray diffraction data were collected to $2.5{\AA}$ resolution from the wild-type crystals and to $1.8{\AA}$ from the crystals of the double mutant, since the latter produced better quality diffraction data. The wild-type crystals belonged to the monoclinic space group C2 ($a=155.64{\AA}$, $b=44.54{\AA}$, $c=71.53{\AA}$ and ${\beta}=96.39^{\circ}$) and the P28L/Y173F crystals to the monoclinic space group $P2_1$ ($a=71.09{\AA}$, b=52.70, $c=71.52{\AA}$ and ${\beta}=91.49^{\circ}$). The asymmetric unit of both structures contained two molecules of ${\alpha}TS$. Crystal volume per protein mass ($V_m$) and solvent content were $2.15{\AA}^3\;Da^{-1}$ and 42.95% for the wild-type and $2.34{\AA}^3\;Da^{-1}$ and 47.52% for the double mutant.

• 한국미생물·생명공학회지
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• 제18권4호
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• pp.352-359
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• 1990

분쇄마찰매체효소반응계에서 glucoamylase와 Alpha-amylase의 보완작용에 의한 옥수수 생전분의 효소당화 mechanism을 규명코자, 분리.정제된 상기 효소의 혼합 비율에 따른 당화양상 및 생성당 조성, 전분입자 구조, 생전분입자의 particle size 분포, X-ray 회절양샹의 변화 등을 관찰하였다. 분쇄마찰매체 효소반응계에서도 효소를 분리하여 사용하였을 때보다 glucoamylase와 $\alpha$-amylase를 혼합사용할 경우 당화율이 크게 향상되었으며, 고순도의 glucose 생산에 적합한 두 효소의 혼합비율은 약 1:1-1:2(unit) 로 판명되었다.

• 약학회지
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• 제40권4호
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• pp.382-386
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• 1996

The compound of the 6,7-dichloroquinoline-5,8-dione has two asymmetric chloro radicals at the position of the C6 and C7. When the compound reacts with ethyl acetoacetate in the presence of sodium ethoxide, it is considered that C6 and/or C7 position of the compound can be substitued. The exact substitued position of the product (I) could not be identified by the NMR analysis in our experiment. Therefore, we synthesized the 3-ethoxycarbonyl-2-methyl-1-N-propyl pyridino(2,3f)indole-4,9-dione by reaction of the product (I) with propylamine via intramolecular cyclization to identify the substitued position of the product (I) using the X-ray crystallographic structure analysis. The result demonstrates that the position of nucleophilic substitution of the product (I) is at the position of the C6.