• 한국재료학회지
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• 제8권3호
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• pp.224-228
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• 1998

비정량적 조성을 가진 비정질 산화타이타늄 박막을 반응성 스퍼터링으로 제조한후, $500^{\circ}C$~$600^{\circ}C$에서 10분-3시간 열처리후 냉각속도를 달리하였을 때의 상변태과정을 고찰하였다. 10분-30분정도의 단기간의 열처리후 급냉한 경우에는 Mageneli상이 관찰되어 비정상정 상($TiO_{2-x}$)이 산화되는 속도가 결정화속도보다 훨씬 느린 것으로 생각되었다. 그러나 열처리 유지시간이 증가하면 $500^{\circ}C$에서 부터의 느린 냉각과정에서는 Magneil가 anatase로 변화하며 변태한 anatase는 저온에서는 rutile로 변화하지 않았으나 $500^{\circ}C$~$300{\circ}C$의 온도 구간을 비교적 빠르게 냉각하면 Matneli상은 직접 rutile상으로 변화할 수 있는 것으로 고찰되었다. 또한 $600^{\circ}C$에서 냉각시에도 rutile상이 형성됨으로서 rutile상은 $500^{\circ}C$이상의 고온에서도 이 상ㅇ르 거치지 않고 변태할 수 있는 것으로 분석된다. 결정화 및 산화과정은 부피의 변화를 야기하여 박막의 표면 형상의 변화도 가져옴이 관찰되었다.

• 한국재료학회지
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• 제9권5호
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• pp.503-508
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• 1999

We have investigated the physical and diffusion barrier property of Ti-Si-N film for Cu metallization. The ternary compound was deposited by using reactive rf magnetron sputtering of a TiSi$_2$target in an Ar/$N_2$gas mixture. Resistivities of the films were in range of 358$\mu$$\Omega$-cm, to 307941$\mu$$\Omega$-cm, and tended to increase with increasing the $N_2$/Ar flow rate ratio. The crystallization of the Ti-Si-N compound started to occur at 100$0^{\circ}C$ with the phases of TiN and Si$_3$N$_4$identified by using XRD(X-ray Diffractometer). The degree of the crystallization was influenced by the $N_2$/Ar flow ratio. The diffusion barrier property of Ti-Si-N film for Cu metallization was determined by AES, XRD and etch pit by secco etching, revealing the failure temperature of 90$0^{\circ}C$ in 43~45at% of nitrogen content. In addition, the very thin compound (10nm) with 43~45at% nitrogen content remained stable up to $700^{\circ}C$. Furthermore, thermal treatment in vacuum at $600^{\circ}C$ improved the barrier property of the Ti-Si-N film deposited at the $N_2$(Ar+$N_2$) ratio of 0.05. The addition of Ti interlayer between Ti-Si-N films caused the drastic decrease of the resistivity with slight degradation of diffusion barrier properties of the compound.

• 대한기계학회논문집A
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• 제39권8호
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• pp.781-785
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• 2015

엔지니어링 플라스틱(Engineering Plastic ; EP)에 대한 내구성 평가를 위해 현재 새롭게 국내에서 개발한 초음파 피로시험법을 이용하여 EP 중에서도 결정화 속도가 빠르고 결정화도가 높은 범용 POM(Polyoxymethylene) 소재에 대한 초음파 가속피로시험 거동을 평가하고자 하였다. 이에 본 연구에서 사용된 POM 소재의 밀도는 $1.37g/cm^3$, 동탄성계수는 3.49 GPa 로 측정되었으며, 초음파피로시험 20kHz, 응력비 R= -1 의 판상시편 두께 (4t, 7t, 10t)에 따른 피로수명평가 결과 전체 응력진폭 5.0~6.0MPa 부위에서 피로한도를 확인하였다. 피로시험 후 파단 면을 관찰한 결과 7t, 10t 두께 시편의 크랙 시작위치에서 미소 공동들이 서로 연결된 형태의 잔금(crazing) 균열현상으로 파단된 dimple 구조형상을 전자현미경을 통해 확인할 수 있었다.

• 공업화학
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• 제25권6호
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• pp.564-569
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• 2014

지르코니아 나노분말을 수열합성법으로 제조하였으며, 반응온도, 반응시간, 침전제의 종류 및 농도, 전구체의 종류를 실험 변수로 하였고, 각각의 제조된 분말을 X-선 회절(XRD)과 주사전자현미경(FE-SEM)을 통해 입자크기 및 결정상을 측정하였다. 침전제의 농도 증가에 따라 지르코니아 입자크기가 증가하였으며, 입자의 결정화도도 높아졌고, KOH 보다 NaOH 침전제를 사용하였을 경우, 입자 성장 속도가 증가하였다. 이는 입자의 크기 컨트롤에 있어 NaOH를 사용하는 경우보다 KOH를 사용하는 것이 더 효과적이었다. 4 h의 수열반응시간에서는 4 h의 수열반응시간에서는 비정질의 지르코니아 입자가 발견되었지만, 8 h 이상 합성 시, 단사정상의 지르코니아 입자가 생성됨을 확인하였고, 반응시간이 길어짐에 따라 지르코니아 입자의 폭이 소폭으로 줄어들고, 길이는 소폭 늘어남을 확인하였다. 동일한 합성 조건에서 전구체로서 zirconium (IV) acetate, zirconium nitrate, zirconium chloride 중에서 zirconium chloride를 사용하여 합성하였을 경우, 입자의 크기가 가장 작게 형성되었다.

• 한국식품위생안전성학회지
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• 제18권3호
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• pp.146-152
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• 2003

당 대사에 관여하는 Pyruvate dehydrogenase phosphatase (PDP)는 해당과정에서의 대사 산물인 pyruvate 를 acetyl CoA로 만들어 구연산 회로로 진입시켜주는 효소인 Pyruvate dehydrogenase complex(PDP)의 활성을 조절하는 중요한 효소이다. PDP의 catalytic subunit는 PDP의 dihydrolipoamide acetyltransferase(E2), PDP regulatory subunit (PDPr), 그리고 칼슘 결합 도메인 등으로 구성되어 있는 것으로 추측되어지고 있다. 본 연구에서는 PDP 단백질을 분리정제하고 결정화 하고자하였다. PDP는 catalytic subunit(PDPc, Mr 52,600 Da)과, regulatory subunit (PDPr, 95,600 Da)으로 구성되어 있으며 칼슘 존재하에 PDPc는 dihydrolipoamide acetyltransferase(E2) component와 결합하여 기질인 인산 E1 component의 탈인산화율을 증가시킨다. PDPc는 intrinsic 칼슘 결합부위를 가지며 두 번째 칼슘 부위는 E2 존재 하에 형성된다. 이러한 특이한 상호반응을 이용한 GSH-Sepharose-GST-L2 matrix를 이용하여 약 1000 U/mg의 specific activity를 갖는 순수 PDPc를 약 80%의 yield로 얻어 결정화에 사용하였다.

• Journal of Pharmaceutical Investigation
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• 제41권3호
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• pp.125-142
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• 2011

Solid dispersion, defined as the dispersion of one or more active ingredient in a carrier or matrix at solid state, is an efficient strategy for improving dissolution of poorly water-soluble drugs for enhancement of their bioavailability. Compared to other conventional formulations such as tablets or capsules, solid dispersion which can be prepared by various methods has many advantages. However, despite numerous studies which have been carried out, limitations for commercializing these products remain to be solved. For example, during the manufacturing process or storage, amorphous form of solid dispersion can be converted into crystalline form. That is, the dissolution rate of solid dispersion would continuously decrease during storage, resulting in a product of no value. To resolve these problems, studies have been conducted on the effects of excipients. In fact, modification of the solid dispersions to overcome these disadvantages has progressed from the first generation to the recent third generation products. In this review, an overview on solid dispersions in general will be given with emphasis on the various manufacturing processes which include the use of polymers and on the stabilization strategies which include methods to prevent crystallization.

• Elastomers and Composites
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• 제40권3호
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• pp.212-221
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• 2005

유연사슬길이가 6인 4,4'-bis(6-hydroxy hexoxy)biphenyl (BP-6)의 메소겐 디올을 합성하였고, 이것을 4,4'-diphenylmethane diisocyanate (MDI)와 용액축중합하여 폴리우레탄 (MPU-6)을 합성하였다. 합성된 MPU-6는 $0.23{\sim}0.56 dL/g$의 고유점도를 보였다. MPU-6는 X-ray, 편광현미경으로부터는 액정을 형성할 수 있었으나, DSC로 분석 시에는 액정거동을 관찰할 수 없는 '가상액정'의 거동을 보였다. 또한 MPU-6의 분자량이 낮을수록 결정화 속도와 결정화 온도가 높음을 알 수 있었으며 이는 분자량이 낮을수록 고분자의 mobility가 증가함으로써 메소겐기의 배향이 용이하고, 이것이 기핵으로 작용하였기 때문으로 생각된다.

• 한국광물학회지
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• 제4권2호
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• pp.69-89
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• 1991

The anorthositic rocks and the many other plutons which are of different varieties and age were distributed in the northern extremity of the distributed areas of H-S anorthositic rocks. The purpose of this study was to find plutons which had comagmatic relationships, and to make clear the magmatic process of anorthositic magma. The plutons were classified, and the petrological and the geochemical characteristics of the plutons were compared and researched in this study. And, because, like anorthosite, the rocks which intrude in the deep crust accompany assimilation, an AFC model calculation was performed to make the differentiation process of the anorthositic rocks clear. The plutons in this area were classified into three groups, and the three groups were composed of the Precambrian anorthositic rocks and related rocks, the Jurassic gabbro, and the plutons of undnown age. The anorthositic magma was differentiated from the anorthositic rocks through the tonalite to the alkali-feldspar granite, and it was differentiated under K, Mg, Fe free/lack condition. It was found from the result of AFC model that the anorthositic rocks were differentiated by fractional crystallization, but they were assimilated with wall-rocks, and the assimilation was performed at the rate of r$\leq$0.1. The plutons which intruded the anorthositic rocks subsequently consisted of the gabbro, the megacrystic granite, the fine-grained granite, and the gneissose granite. But they were formed by the repeated intrusion of magma, which may, or may not, be of the same origin. According to the result of the RCF model, these plutons were differentiated by simple fractional crystallization, and they were assimilated relatively less than the anorthositic rocks.

• 자원환경지질
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• 제32권6호
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• pp.669-688
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• 1999

The Yeongju granitoid batholith is a plutonic complex of huge area (1180km2) intruding the metamorphic rocks of the Yeongnam massif. The batholith, which is divided into fivelithofacies, consists of three separate plutons. The oldest Buseok pluton comprises four lithofacies: hornblende biotite tonalite, porphyrotoc biotite granodiorite, equigranular biotite grandiorite and biotite granite. The middle Chunyang pluton has been called as Chunyang granite that ranges in compostion from granodiorite to granite. The youngest Jangsu pluton is intrusions that has lithofacies of two mica granite. The contact between Buseok pluton and the rest two plutons shows obvious intrusive relations, but relation between the Chunyang and the Jangsu pluton is far away, so gives no indication of relative ages. Changes in nextures and micristructures, as well as in the mineral contents, take place between rock types og the plutons. only the Buseok pluton shows faliations of two type: magmatic foliation and regional mylonal foliation. K-Ar age deteminations fall into 171.7$\pm$3.2~162.3$\pm$3.1 Ma in the Buseok pluton, 153.9$\pm$2.9 Ma in the Chunyang pluton and 145.3$\pm$2.7 Ma in the jangsu Pluton. The batholith presents three separate intrusive phases which range in composition from tonalite to granite to granite. Each intrusive phase apperars to have been intruded in a pulse from an underlying, differentiating magma. The petrochemical data showthat three plutons are within the diagnostic range for continental arc orogenic tectonic setting, whereas Jangsu pluton approaches postorogenic setting. The data suggest that three plutons are calc-aclkalline series, and that temporal compositional variations change progerssively from tonalite through grandiorite to granite between the intrusive phases. so we consider that the magmas for all the phases were probably derived from a differentiation by fractional crystallization of a parental magma. The tonalite magma of the Buseok phase was tapped was tapped from a chamber deep in the crust, and then would have to rise at a rapid rate to its final level of emplacement. The tonalite magma in the chamber was gradually enolved through granodiorite magma into granite magma by fractional crystallization. The magmas of the younger phases were respectively tapped with temporal interval from a evolved magma of the chamber that rose into a shallower lever in the crust, and rose to their present level of emplacement.

• 한국결정성장학회지
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• 제13권1호
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• pp.5-14
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• 2003

Principles of a novel pulse growing method are described. The method realized in the crystal growing on a seed from melts under raw melt feeding provided a more reliable control of the crystallization process when producing large alkali halide crystals. The slow natural convection of the melt in the crucible at a constant melt level is intensified by rotating the crucible, while the crystal rotation favors a more symmetrical distribution of thermal stresses over the crystal cross-section. Optimum rotation parameters for the crucible and crystal have been determined. The spatial position oi the solid/liquid phase interface relatively to the melt surface, heaters and the crucible elements are considered. Basing on that consideration, a novel criterion is stated, that is, the immersion extent of the crystallization front (CF) convex toward the melt. When the crystal grows at a <> CF immersion, the raised CF may tear off from the melt partially or completely due to its weight. This results in avoid formation in the crystal. Experimental data on the radial crystal growth speed are discussed. This speed defines the formation of a gas phase layer at the crystal surface. The layer thickness il a function of time a temperature at specific values of pressure in the furnace and the free melt surface dimensions in the gap between the crystal and crucible wall. Analytical expressions have been derived for the impurity component mass transfer at the steady-state growth stage describing two independent processes, the impurity mass transfer along the <> path and its transit along the <> one. The heater (and thus the melt) temperature variation is inherent in any control system. It has been shown that when random temperature changes occur causing its lowering at a rate exceeding $0.5^{\circ}C/min$, a kind of the CF decoration by foreign impurities or by gas bubbles takes place. Short-term temperature changes at one heater or both result in local (i.e., at the front) redistribution of the preset axial growth speed.