• 한국발생생물학회지:발생과생식
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• 제4권2호
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• pp.181-186
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• 2000

생쥐 난소에서 glucosamine-6-phosphate deaminase (GNPDA)의 발현을 조사하였다. Western blot상에서 Mr. 31 kDa의 항원을 검출하였으며 출생 후2주에 급격한 발현의 증가가 확인되었다. 난소절편의 면역염색 결과 협막세포와 간충조직에서는 균질한 발현을 보인 반면 난포내 발현양상은 난포의 발달에 따라 다르게 나타났다. 일부 1차 난포의 난자에서 GNPDA의 발현이 관찰되었으나 강소형성 난포의 난자에서는 관찰되지 않았다. 황체화 과립세포에서의 발현은 황체발달에 따라 증가하였으며 황체퇴화 부위에서 강한 신호가 검출되었다. 난포발달에 따른 GNPDA발현의 차이는 GNPDA가 생쥐 난소 조직 재구성에 관여하고 있음을 암시한다.

• 한국세라믹학회지
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• 제30권1호
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• pp.7-16
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• 1993

Effect of sulfate on the reactionof C3S formation in presence of clinker melt and its appearance in clinker were investigated, using (NH4)2SO4 and CaSO4 as sulfate sources. When (NH4)2SO4 and CaSO4 were added, both showed the similar results, 1.0wt% of sulfate could promoted the reaction of C3S formation, however for its content of more than 2.0wt%, the formation of C3S was prevented. Residual limit of sulfate to C3S formation is about 1.4wt%. Appearances of sulfate were C4A3l and CaSO4 in interstitial phase. For the addition of (NH4)2SO4 or CaSO4 of 20wt%~4.0wt%, C3S grains showed the hypertrophic growth. We might consider that, because sulfate reduced the surface tension and viscosity of the clinker melt, C3S crystals were precipitated below 140$0^{\circ}C$, and the crystlas of C3S were coalesced and linked in the same crystallographical direction with increasing temperature becuase of their rapid growth rate.

• 한국세라믹학회지
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• 제48권6호
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• pp.589-594
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• 2011

Raw mix of molten clinker was fabricated using blast furnace slag as starting material. Raw mix was melted at 1620$^{\circ}C$ for molten clinker fabrication. It was found that molten clinker contained alite and belite equivalent to OPC clinker mineral by optical microscope and SEM. The size of alite was 10~50 ${\mu}m$ and that of belite was 20~80 ${\mu}m$. This result thought to be attributed low $Al_2O_3$ content and cooling condition. Interstitial phase increased with blast furnace slag content and gehlenite was formed by the condition of LSF and SM. So raw mix with 27~41% blast furnace slag could be converted into cement clinker by appropriate choice of melting andcooling methods in this study.

• Corrosion Science and Technology
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• 제7권1호
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• pp.1-5
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• 2008

The gas atmosphere in continuous annealing and galvanizing lines alters both composition and microstructure of the surface and sub-surface of sheet steel. The formation and morphology of the oxides of alloying elements in High Strength Interstitial Free (HS-IF), Dual Phase (DP) and Transformation-Induced Plasticity (TRIP) steels are strongly influenced by the furnace dew point, and the presence of specific oxide may result in surface defects and bare areas on galvanized sheet products. The present contribution reviews the progress made recently in understanding the selective formation of surface and subsurface oxides during annealing in hot dip galvanizing and conventional continuous annealing lines. It is believed that the surface and sub-surface composition and microstructure have a pronounced influence on galvanized sheet product surface quality. In the present study, it is shown that the understanding of the relevant phenomena requires a combination of precise laboratory-scale simulations of the relevant technological processes and the use of advanced surface analytical tools.

• Archives of Metallurgy and Materials
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• 제66권3호
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• pp.729-733
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• 2021

Ferrotitanium can be produced as a method of recycling Ti scraps. The eutectic composition of ferrotitanium, Fe_29.5Ti_70.5, can be obtained as a nanocrystalline phase due to relatively low melting point. Fe_29.5Ti_70.5 in which FeTi and β-Ti form a lamellar structure have high strength but low strain. To improve this, impurities were removed through hydrogen plasma arc melting (HPAM) and annealed. HPAM can remove substitutional/interstitial solid solutions. As a result, from 6733 ppm to 4573 ppm of initial impurities were removed by HPAM process. In addition, the strain was improved by spheroidizing and coarsening the lamellar structure through annealing. The effect of impurities removed through HPAM on the Young's modulus, yield strength, and strain was observed.

• KSBB Journal
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• 제13권5호
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• pp.577-584
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• 1998

A sensitive membrane strip assay for plasma lipoprotein cholesterol that can be performed without handling reagents has been investigated. We previously developed an assay system with immobilized enzymes (cholesterol esterase and cholesterol oxidase) on the surfaces of nitrocellulose membrane(1). In such a case, the amount of enzymes present on the membrane was limited by its surface area and, thus, the detection capability was relatively poor (> 50 mg/dL cholesterol). To overcome this problem, we devised a new system with non-immobilized enzymes by placing them within interstitial spaces of a celullose membrane pad in a dry state. Upon contact with sample medium, the enzymes were immediately dissolved and participated in the reactions with cholesterol in a liquid phase. We constructed a user-friendly system consisting of four membrane pads fro sample application, cholesterol decomposition, color development as signal, and medium absorption to invoke a continuous flow (sequential location from the bottom). A sample containing lipoproteins was added into the application pad by capillary action and transferred to the next pad for decomposition. The decomposition pad (namely, enzyme pad) contained a detergent (sodium cholate) for the destruction of lipoprotein particles, the two enzymes for cholesterol decomposition, and a chromogen (3,3'-diaminobenzidine). As a consequence of the enzyme reactions, hydrogen peroxide was produced, and then reacted in the presence of the chromogen with horseradish peroxidase immobilized on the signal generation pad. Finally, a colorimetric signal directly proportional to the cholesterol concentration was produced. The detection limit determined from this system under optimal conditions was at least 2 times lower than of the enzyme-immobilized system.

• 한국재료학회지
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• 제22권3호
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• pp.150-154
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• 2012

Ti-6Al-4V ELI (Extra Low Interstitial) alloy have been widely used as alternative to bone due to its excellent biocompatibility, although it still has many problems such as high elastic modulus and toxicity. Therefore, biomaterials with low elastic modulus and non toxic characteristics have to be developed. A novel ${\beta}$ Ti-35wt%Nb-7wt%Zr-Calcium pyrophosphate (CPP) composite that is a biocompatible alloy without elemental Al or V was fabricated by spark plasma sintering (SPS) at $1000^{\circ}C$ under 70 MPa using high energy mechanical milled (HEMM) powder. The microstructure and phases of the milled powders and the sintered specimens were studied using SEM, TEM, and XRD. Ti-35wt%Nb-7wt%Zr alloy was transformed from ${\alpha}$ phase to ${\beta}$ phase in the 4h-milled powder by sintering. The sintered specimen using the 4h-milled powder showed that all the elements were distributed very homogeneously and had higher density and hardness. ${\beta}$ Ti alloy-CPP composite, which has nanometer particles, was fabricated by SPS using HEMMed powder. During the sintering process, $CaTiO_3$, TixOy, and CaO were formed because of the reaction between Ti and CPP. The Vickers hardness of the composites increases with the increase of the milling time and the addition of CPP. The biocompatibility of the Ti-Nb-Zr alloys was improved by addition of CPP.

• 한국자기학회지
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• 제3권2호
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• pp.87-93
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• 1993

질화철(Fe-N) 박막을 DC magenetron sputtering 방법으로 증착하였다. 스퍼터링 기체중의 질소유량비와 스퍼터링 power가 박막의 구조와 조성, 자기적 특성에 미치는 영향을 조사하였다. 증착 박막중의 질소원자 함유량은 박막의 구조, 생성상 및 자기적 특성을 결정짓는 지배적인 인자이다. 낮 은 질소 유량비에서 증착하였을 경우 박막은 질소 침입형 $\alpha$-Fe 결정구조를 갖으며, 질소원자 함유량에 비례하여 격자변형은 증가하고 포화자화값은 감소하였다. 격자변형이 어느 정도 심하게 일어 나면 주상정으로의 성장이 억제되어 평탄한 표면형상과 균일한 미세구조를 갖게되며, 자구벽의 이동이 용이하게 되어 보자력의 급격한 감소를 가져왔다. 질소유량비가 증가하여 박막내의 질소함유량이 15 at.%가 되면 격자정수 d(110)이 5% 증가하게 되며 이때 $Fe_{2-3}N$ 상으로의 상변화가 일어나 포화 자화값은 급격히 감소한다.

• 한국건설순환자원학회논문집
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• 제10권3호
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• pp.211-218
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• 2022

석탄재는 시멘트 클링커의 실리카와 알루미나질 공급원으로서 활용이 고려되고 있다. 이러한 석탄재의 시멘트 클링커 소성과정에서 소성온도에 따른 고온 미세구조변화를 검토하여, 시멘트 클링커 소성에서 미치는 영향을 파악하고자 하였다. 시멘트 클링커의 원료로서 사용된 석탄재는 소성온도 950 ℃부터 입자 표면의 형상변화가 관찰되었으며, 1250 ℃ 이상의 소성온도에서 부터는 석탄재의 형상이 소멸되었다. 석탄재의 Al, Fe 성분은 1350 ℃ 이상의 온도에서는 시멘트 간극상으로 전환되는 되는 것을 확인하였다. 또한, 다량의 석탄재를 원료로 적용한 클링커는 1150~1200 ℃의 소성온도 구간에서 Lime의 함량이 낮고, Belite의 함량이 높게 나타나, 석탄재의 적용으로 초기 소성온도에서 칼슘실리케트 광물의 형성이 더 원활하게 진행되는 것을 확인하였다.

• 한국발생생물학회지:발생과생식
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• 제6권2호
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• pp.123-129
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• 2002

비만유전자 산물인 leptin은 비만뿐만 아니라 여성의 생식 생리와 관련이 있는 것으로 보이나, 아직 이러한 leptin이 난소에 직접적으로 작용하는지 정확하게 밝혀지지 않고 있다. 따라서 본 연구에서는 흰쥐 난소에서 leptin과 leptin 수용체의 발현을 면역조직화학방법으로 확인하고 발정주기에 따른 leptin과 leptin 수용체의 발현 양상을 RT-PCR 방법으로 조사하고자 하였다. 면역조직화학적 염색방법 결과 흰쥐 난소내에서 leptin은 협막세포와 폐쇄 난포의 일부 과립세포에 염색되었고, leptin 수용체는 협막세포, 간질세포와 난포강이 형성되지 않은 난포의 난자에 염색되었다. 특히 폐쇄 난포에서는 leptin과 leptin 수용체가 정상 난포에 비해 강하게 염색되었다. 흰쥐의 발정주기 동안 혈청내 estradiol, progesterone leptin의 농도는 ELISA 방법으로 측정하였고, 난소내 leptin과 leptin 수용체의 mRNA 발현 양상은 RT-PCR 방법으로 조사하였다. 혈중 leptin 농도를 측정한 결과 estrous 시기에 비하여 metestrous 시기에 유의하게 증가하였고, 이 시기에 progesterone 농도가 함께 증가하는 것을 관찰할 수 있었다. Leptin mRNA는 모든 발정주기에서 발현되지 않았지만 leptin 수용체 mRNA는 diestrous 시기를 제외한 다른 발정주기에 모두 발현되었다. 이러한 결과는 leptin이 흰쥐 난소의 기능을 조절하는데 직접적으로 관여할 수 있다는 것을 제시하고 있다.