• 폴리머
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• 제34권5호
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• pp.480-484
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• 2010

무수산인 4,4'-(4,4'-isopropylidene-diphenoxy)bis(phthalic anhydride)(BPADA)와 아민계인 2,2'-bis(trifluoromethyl)benzidine(TFB), bis(3-aminophenyl)sulfone(APS), 4,4'-methylene-bis-(2-methylcyclohexylamine)(MMCA), bis[4-(3-aminophenoxy)phenyl]sulfone(BAPS)에 melamine을 각각 5 몰%로 반응시켜 N,N'-dimethylacetamide(DMAc) 용매 속에서 폴리아믹산(poly(amic acid), PAA)들을 얻었다. 용액 상태의 PAA를 캐스팅하여 각각 다른 반응 온도에서 열처리를 통해 무색 투명한 폴리이미드(PI) 필름을 얻었다. PI의 열적 성질, 광학적 특성을 다양한 아민 구조의 변화에 따라 조사하였으며, 열적 성질은 differential scanning calorimetry(DSC), thermogravimetric analysis(TGA), thermomechanical analysis(TMA)를 이용해 측정하였고, 광학적 투명도는 색차계(spectrophotometry)를 이용하였다. 제조된 모든 필름의 열 팽창계수는 $48.53-64.24ppm/^{\circ}C$ 사이의 값을 얻었으며, 모든 필름 시료의 노란색 지수(yellow index, YI)는 3 이하를 나타내었다.

• Journal of the Korean Wood Science and Technology
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• 제43권3호
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• pp.334-343
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• 2015

본 연구에서는 국내에서 상업적으로 이용되고 있는 국산 낙엽송 열처리재의 여러 가지 물성(밀도, 평형함수율, 수축률, 흡습/흡수성, 종/횡압축강도, 휨강도, 경도, 내부후성능)을 정량적으로 평가하기 위하여 수행되었다. 고온처리에 의해 목재의 소수성이 증가함에 따라 평형함수율이 감소하였다. 이에 따라 수축률 및 흡습/흡수성이 감소하여 치수안정성이 개선되었고, 낮은 함수율의 영향으로 압축강도가 증가하였으며, 목재 주성분의 변화와 낮은 함수율의 영향으로 내부후성능이 개선되었다. 하지만 열처리에 의해 밀도와 휨강도 및 경도는 감소하였다.

• 한국재료학회지
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• 제4권2호
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• pp.241-249
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• 1994

항공기용 고력 AI합금인 7075 AI합금의 물성개선을 위한 가공열처리 방안으로서 과시효처리후 온간 및 냉간 압연에 의한 소성가공이 재결정조직과 강도에 미치는 영향에 대하여 연구하였다. 소송가공후 재결정처리에 의해 결정립을 미세화하는 공정에서 소성가공 전 과시효를 함으로써 재결정립의 미세화 정도는 더욱 현저하였다. 이는 과시효에 의한 조대한 석출물이 재결정처리시 핵생성 site로서 작용하였음을 의미한다. 본 연구에서 항복강도와 재결정립의 크기와는 Hall-petch식을 만족하지 않았으며 이는 등축이 아닌 연신된 결정조직에 기인된 결과로 보이며, 항복강도가 재결정립의 종횡비에 직선적으로 비례하였다. 또한 결정립 미세화를 통한 강도, 인성향상을 목적으로 하는 TMT(Thermo mechanical Treatment)공정에서는 심한 냉간가공에 의해서보다는 온간에서의 소성가공이 바람직함을 알 수 있었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 초전도 자성체 연구회
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• pp.34-37
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• 2003

본 연구는 고온초전도 coated coductors의 기판으로 cube texture된 순수 Ni 기판을 개발하기 위하여 전체 가공율과 압연율에 따른 (100) texture의 변화와 1차적으로 열처리한 기판을 다시 압연한 후 재열처리 하였을 때의 전체 가공율과 압연율에 따른 (100) texture의 변화를 GADS XRD와 SEM을 이용하여 연구하고자 하였다. 그 결과, 압연 후에는 압연율에 관계없이 비교적 약한 강도의 (220)과 (200), (111), (311) peak가 나타났는데, 4%로 압연했을 경우 (220) peak가 가장 강한 peak로 나타난 반면, 10%로 압연한 경우에는 (200) peak가 비교적 강하게 나타났다. 그러나 이를 $900^{\circ}C$에서 열처리한 후에는 (200) peak 만 뚜렷이 발달되어 나타났는데, 전체 가공율과 압연율이 높을수록 (200) peak의 강도가 높게 나타나 압연을 통하여 발달한 결정립자의 (110) 면을 따른 배열이 열처리 과정을 통하여 회전하여 (100)면을 따른 배열로 바뀌는 것으로 추측할 수 있었다. 그러나 $900^{\circ}C$에서 열처리한 두께 0.2mm 판재를 다시 0.1mm까지 4%와 10%의 압연율로 압연하고 500~$900^{\circ}C$에서 1시간동안 최종 열처리한 후에는 상대적으로 낮은 2차 가공율에 의하여 집합조직의 전체 가공율과 압연율에의 의존성이 사라지는 것으로 나타났다.

• 한국약용작물학회지
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• 제17권6호
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• pp.379-387
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• 2009

The aim of this investigation was to examine the influence of extrusion on dietary fiber profile and the content of bioactive compounds, rutin and quercetin in young sprout, whole seed, and matured stem of Tartary buckwheat. WSI(water soluble index) is increased by a function of both screw profile and process temperature, compared to control in different parts of Buckwheat. Also, WSI of ME is increased more than 5.2 times in grain, compared to that of control. The effect of precooking by extrusion on the dietary fiber profile of buckwheat flour was evaluated. Precooking by extrusion significantly increased SDF in flour, although in most cases extrusion decrease in TDF a little. The thermo-mechanical treatment undergone by the buckwheat flour during extrusion led to redistribute part IDF fraction to SDF, leading to an increase in the latter. The content of rutin was increased about two fold in extruded flour of sprout, compared to in control. This increase maybe why these compounds are released from cell wall by high shear processing under high temperature.

• 대한금속재료학회지
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• 제49권12호
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• pp.995-1000
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• 2011

The microstructure of Cu-24 wt.%Ag filamentary nanocomposite fabricated by a thermo-mechanical process has been investigated by transmission electron microscopy (TEM) observations. This study is focused on the stability of Ag filaments formed by cold drawing; the effects of thermal treatment on the precipitation behavior and distribution of Ag-rich precipitates were also investigated. The Ag filaments elongated along the <111> orientation were observed in Cu-rich ${\alpha}$ phase of the as-drawn specimen and the copper matrix and the silver filament have a cube on cube orientation relationship. Annealing at temperatures lower than $200^{\circ}C$ for the as-drawn specimen caused insignificant change of the fibrous morphology but squiggly interfaces or local breaking of the elongated Ag filaments were easily observed with annealing at $300^{\circ}C$. When samples were annealed at $400^{\circ}C$, discontinuous precipitation was observed in supersaturated Cu solid solution. Ag precipitates with a thickness of 7-20 nm were observed along the <112> direction and the orientation relationship between the copper matrix and the Ag precipitates maintained the same orientation relationship in the as-drawn specimen. The interface between the copper matrix and the Ag precipitates is parallel to {111} and micro-twins were observed in the Ag precipitates.

• 열처리공학회지
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• 제5권1호
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• pp.41-49
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• 1992

The effects of alloying elements on the superplastic properties of Al-Li based alloys had been investigated. The intermediate thermo-mechanical treated (ITMT) Al-2.0wt%Li, Al-2.0wt%Li-1.0wt%Mg, Al-2.0wt%Li-0.12wt%Zr and Al-2.0wt%Li-1.2wt%Cu-1.0wt%Mg-0.12wt%Zr alloys were tested in tension at various temperature (400, 450, 500 and $550^{\circ}C$) and strain rate($6.7{\times}10^{-3}$, $1.0{\times}10^{-2}$, $1.6{\times}10^{-2}$ and $5.0{\times}10^{-2}/sec$). The results were as follows : The superplasticity in binary, ternary and pentanary alloys appeared at 500 to $550^{\circ}C$, and good strain rate for superplasticity. $1.6{\times}10^{-2}/sec{\sim}1.0{\times}10^{-2}/sec$ for a binary alloy and $1.0{\times}10^{-2}/sec{\sim}6.7{\times}10^{-3}/sec$ for ternary and pentanary alloys. A Zr-added ternary alloy had best value of elongation (730%) in four alloys at $550^{\circ}C$ of tension temperature and $1.0{\times}10^{-2}/sec$ of strain rate. The strain rate was greatly dependent on tension temperature and true strain rate was more than 1.0 at all test temperature and strain rate. In binary and Mg-added teranry alloys. the necks were slightly formed and their fracture surface had lips shape, but Zr-added ternary and pentanary alloy fractured along the grain boundary without necking. Their dislocations moved to grain boundary during superplasticity deformation and arranged perpendicular to grain boundary. Super plastic deformation was made by grain boundary slip of dislocation slip creep and model of core and mantle.

• Asian Pacific Journal of Cancer Prevention
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• 제15권1호
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• pp.49-54
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• 2014

Background: Hydrogels are a class of polymers that can absorb water or biological fluids and swell to several times their dry volume, dependent on changes in the external environment. In recent years, hydrogels and hydrogel nanocomposites have found a variety of biomedical applications, including drug delivery and cancer treatment. The incorporation of nanoparticulates into a hydrogel matrix can result in unique material characteristics such as enhanced mechanical properties, swelling response, and capability of remote controlled actuation. Materials and Methods: In this work, synthesis of hydrogel nanocomposites containing magnetic nanoparticles are studied. At first, magnetic nanoparticles ($Fe_3O_4$) with an average size 10 nm were prepared. At second approach, thermo and pH-sensitive poly (N-isopropylacrylamide -co-methacrylic acid-co-vinyl pyrrolidone) (NIPAAm-MAA-VP) were prepared. Swelling behavior of co-polymer was studied in buffer solutions with different pH values (pH=5.8, pH=7.4) at $37^{\circ}C$. Magnetic iron oxide nanoparticles ($Fe_3O_4$) and doxorubicin were incorporated into copolymer and drug loading was studied. The release of drug, carried out at different pH and temperatures. Finally, chemical composition, magnetic properties and morphology of doxorubicin-loaded magnetic hydrogel nanocomposites were analyzed by FT- IR, vibrating sample magnetometry (VSM), scanning electron microscopy (SEM). Results: The results indicated that drug loading efficiency was increased by increasing the drug ratio to polymer. Doxorubicin was released more at $40^{\circ}C$ and in acidic pH compared to that $37^{\circ}C$ and basic pH. Conclusions: This study suggested that the poly (NIPAAm-MAA-VP) magnetic hydrogel nanocomposite could be an effective carrier for targeting drug delivery systems of anti-cancer drugs due to its temperature sensitive properties.