• 한국재료학회지
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• 제5권7호
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• pp.820-828
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• 1995

초청정 Si 기판위에 Ti을 증착하여 형성시킨 Ti-silicide의 상전이와 각상의 표면 및 계면형상을 Ti 증착두께, 열처리 온도, 기판의 방위에 따라 조사하였다. 초 고진공 챔버에서 각각 400$\AA$ 및 200$\AA$의 Ti를 50$0^{\circ}C$부터 90$0^{\circ}C$까지 10$0^{\circ}C$간격으로 가열되어 있는 Si(100) 및 Si(111) 기판에 증착하여 Ti-silicide를 형성하였다. 형성된 Ti-silicide를 XRD, SEM, TEM으로 상전이와 각상의 표면 및 계면 형상을 관찰하였다. 관찰결과 C49에서 C54상으로의 상전이 온도는 $650^{\circ}C$정도이었고, 기판의 방위와 박막의 증착 두께에 따라 상전이 온도의 변화가 관찰되었으며, 이 상전이 온도의 변화를 표면에너지와 체적에너지에 기초를 둔 고찰을 통해 설명하였다. 그리고 C49상은 증착한 박막에서의 Si 원자의 비균질한 확산 특성으로 인해 거친 계면을 나타내고 있으나, C54상은 비교적 균질한 계면을 나타내고 있으며 응집화에 의해 island가 형성된 것이 관찰되었다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 하계학술대회 논문집 Vol.4 No.1
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• pp.54-57
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• 2003

[ $HfO_xN_y$ ] films using a hafnium tertiary-butoxide $(Hf[OC(CH_3)_3]_4)$ in plasma and $N_2$ ambient were prepared to improve the thermal stability of hafnium-based gate dielectrics. A 10% nitrogen incorporation into $HfO_2$ films showed a smooth surface morphology and a crystallization temperature as high as $200^{\circ}C$ compared with pure $HfO_2$ films. The $TaN/HfO_xN_y/Si$ capacitors showed a stable capacitance-voltage characteristics even at post-metal annealing temperature of $1000^{\circ}C$ in $N_2$ ambient and a constant value of 1.6 nm EOT (equivalent oxide thickness) irrespective of an increase of PDA and PMA temperature. Leakage current densities of $HfO_xN_y$ capacitors annealed at PDA temperature of 800 and $900^{\circ}C$, respectively were approximately one order of magnitude lower than that of $HfO_2$ capacitors.

• Progress in Superconductivity
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• 제8권1호
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• pp.93-97
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• 2006

YBCO films were deposited on a moving substrate by a spray pyrolysis method using nitrate aqueous solution as precursors. Deposition was made on $LaAlO_3$(100) single crystal substrate by spraying precursor droplets generated by a concentric nozzle. The cation ratio of precursor solution was Y:Ba:Cu=1:2.65:4.5. The distance between nozzle and substrate was 15 cm. Substrate was transported with a speed ranging from 0.23 cm/min to 0.5 cm/min. Films were deposited at the pressure ranging from 10 Torr to 20 Torr and the deposition temperature was ranged from $740^{\circ}C\;to\;790^{\circ}C$. Oxygen partial pressure was controlled between 1 Tow and S Torr. Superconducting YBCO films were obtained from $740^{\circ}C\;to\;790^{\circ}C$ with an oxygen partial pressure of 3 Torr. Scanning electron microscope(SEM) and X-ray diffraction(XRD) observation revealed that films are smooth and highly texture with(001) plans parallel to substrate plane. Highest Jc was 0.72 $MA/cm^2$ at 77K and self-field for the film with a thickness of 0.15 m prepared at a substrate temperature of $740^{\circ}C$ and $PO_2$=3 Torr.

• 대한수의학회지
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• 제34권1호
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• pp.9-18
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• 1994

The morphological changes of Sertoli cells of the Korean native pheasant were studied in the active and inactive spermatogenic phases. Twenty-four male of the pheasants were studied in the active (April~June) and inactive(August~March) phase. These data are useful in studying the male genital organs of the Korean native pheasant. Light microscopic morphological changes of the Sertoli cells were studied on paraffin-embedded sections stained with hematoxylin-eosin stain. Ultrastructural changes of Sertoli cells were investigated of ultrathin section using electron microscope. Results are summarized as follows: During the active phase, the average diameter of seminiferous tubule was $245.33{\pm}29.93{\mu}m$ and was largely decreased by $94.50{\pm}14.10{\mu}m$, and the thickness of interstitial tissue was comparatively increased during the inactive phase. During the active phase, in the cytoplasmic process of Sertoli cell and lipid droplets appeared disperse. Well-developed smooth Endoplasmic Reticulum and microtuble were observed in the cytoplasmic process. The nuclei of Sertoli cells were adjacent to the basement membrane. The size of nuclei was reduced and nuclei of Sertoli cells were densely packed within the tubule. Few collagen fibers, fibroblast and various sizes of lipid droplets were observed in the interstitial cell of the seminiferous tubule.

• 한국재료학회지
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• 제13권6호
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• pp.369-373
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• 2003

Magneto-optic Kerr Effect(MOKE), AFM and magnetoresistance measurements have been carried out on as-deposited and annealed Magnetic Tunnel Junctions(MTJs) with junction sizes 180, 250, 320 and 380 $\mu\textrm{m}$ in order to investigate the correlation among interlayer exchange coupling, surface roughness and junction size. Relatively irregular variations of coercivity $H_{c}$ (∼17.5 Oe) and interlayer exchange coupling $H_{E}$ (∼17.5 Oe) are observed over the junction in as-deposited sample prepared by DC magnetron sputtering. After annealing at $200^{\circ}C$, $H_{c}$ decreases to 15 Oe, while $H_{ E}$ increases to 20 Oe with smooth local variation. $H_{E}$ shows very good correlation with surface roughness across the junction in agreement with Neel's orange peel coupling. The increasing slope per $\mu\textrm{m}$ of normalized $H_{c}$ and $H_{E}$ are same near junction edge along free-layer direction irrespective of junction size, giving relatively uniform $H_{c}$ and $H_{ E}$ for wider junction size. Thickness profiles of the junctions measured with $\alpha$-step show increasingly flat top surface for larger junctions, indicating better uniformity for large. junctions in agreement with the normalized$ H_{c}$ and H$/_{E}$ curves. TMR ratios also increase with increasing junction size, indicating improvement for larger uniform junctions.

• 한국재료학회지
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• 제10권8호
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• pp.525-531
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• 2000

플라즈마 화학증착법을 이용하여 Corning glass 1737 기판에 안티몬 도핑 산화주석 박막을 증착하였다. 플라즈만 화학증착시 반응변수에 따른 박막의 결정상 및 형성된 표면거칠기에 대하여 XRD와 AFM을 이용하여 검토하였다. 반응온도 $450^{\circ}C$, 유입가스비 R[$P_{SbCl}P_{{SnCl}_4}$]=1.12, r.f. power 30W에서 비교적 결정성이 뛰어난 박막을 얻을 수 있었다. 화학증착법(TCVD)에 비해 플라즈마 열화학증착법(PECVD)으로 얻은 박막의 표현형상이 보다 균일하였다. 안티몬 도핑농도가 증가할수록, 증착온고가 낮을수록, 증착두께가 작을수록 박막의 표면거칠기가 보다 감소하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제19권3호
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• pp.30-38
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• 2015

적설한랭지의 경우, 동절기의 동해 및 적설에 의한 교통통행의 원활을 기하기 위하여 제설제를 사용한다. 이와 같은 제설염의 사용은 동결융해 및 염화물에 의해 콘크리트의 급속한 스케일링 피해를 야기시킨다. 이에 대한 피해로 인하여 콘크리트 포장은 콘크리트의 피복두께 감소에 따른 조기 열화 및 사용자의 안정성 등 여러 가지 문제를 발생시킨다. 이에 따라 국외적으로 이와 같은 현상에 대하여 평가를 하기 위해 다양한 시험 및 평가 방법이 제시되고 있다. 하지만 국내에서는 아직 평가방법에 대한 규정은 없으며, 관련 연구 또한 미미한 수준이다. 따라서 본 논문에서는 각 기관 및 나라에서 제시되고 있는 평가방법을 조사하고, 각각의 규정에 따라 실험을 수행하여 결과를 도출하여 비교 분석하였다. 나아가 이와 같은 실험방법과 실험결과의 고찰을 통하여 국내현장에 맞는 실험법을 제안하고자 한다.

• 대한화장품학회지
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• 제25권1호
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• pp.37-54
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• 1999

분체 특성으로 매끄러운 사용감과 피부 부착력이 우수하며 판상의 체질안료보다 유동성이 큰 실리카 미립자를 제조하기 위해 실리카 조대입자의 제조와 이의 다단계 분쇄 공정을 이용하여 여러 층의 terrace를 가지고 있는 판상 체질안료의 표면과 다른 평골한 표면 상태의 평탄면을 가지는 실리카 미립자를 제조하였다 여기에서 제조된 실리카 단일 입자를 모입자로 사용함으로써 이산화티탄의 균일침전반응법에 의해 제조된 복합입자는 평탄면을 가지게 되어 유동성의 조절과 부착력의 조절에 의해 도포 층이 균일하게 형성되는 분체 특성을 가지고 있다 본 실험에서 가장 적합한 침전 반응의 조건은 요소농도가 0.2~0.3mol/$\ell$이고 황산농도가 0.3~O.4mol/$\ell$이고 황산티타닐의 농도가 0.007~0.015mol/$\ell$며, 반응온도는 60~8$0^{\circ}C$였다 이와 같은 균일 침전 반응의 조건에 따라 초미립자상 이산화티탄의 피복량과 피복된 초미립자의 입경을 제어함으로써 분체의 광학적 특성을 조절하였고, 그 결과 피부 도포 시 피부색에서 600nm이상의 장파장 영역에서 반사율을 증가시켜 강한 피부색 tone을 표현할 수 있도록 하였다.

• Journal of Welding and Joining
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• 제20권3호
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• pp.122-128
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• 2002

The laser welding in the automotive industries has been used widely for the butt joint of blank sheets rather than the lap joint of automotive body panels. But as a substitute far the spot welding of automotive body panels, the so called three dimensional laser welding will be important far the body panel engineers. Specially the laser welding of body panels with a smooth weld line is applied increasingly, for example, to the side panels. So far, some criteria of the laser weld quality was suggested by in-house regulations or national standards from experiences and/or rule of thumbs. In the manufacturing places, a go or no-go criterion is adopted because of the simplicity or a lack of rational criteria. It is true specially for the selection of the process parameters, which gives the basic causes for the good quality of laser welds. In this study, the effects of joint combination, gap and welding speed on the lap joint $CO_2$ laser welding of two mild steel sheets with different thicknesses are obtained through a $2{\times}3{\times}7$ factorial experiment. The results of the weld quality are statistically analysed using analysis of variance (ANOVA) and compared between two characteristic zones, which are separated by the type of sectional shapes and the level of input energy per volume. The thickness combinations are 0.8mm/1.2mm, 1.2mm/0.8mm of mild steel sheets. The welding speed covers from the deep penetration to the partial penetration. The gap size has three levels of no-gap, 0.16m, and 0.26mm. The bead width, penetration depth and input energy per volume are measured and used as the weld quality criteria.

• Journal of Welding and Joining
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• 제15권5호
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• pp.134-143
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• 1997

The formation of thick alloyed layer with high Si content have been investigated on the surface of Al alloy (A5083) plate by PTA process with Si powder. Hardening characteristics and wear resistance of alloyed layer was examined in relation to the microstructure of alloyed layer. Thick hardened layer in mm-order thickness on the surface of A5083 plate can be formed by PTA process with wide range of process condition by using Si powder as alloying element because of eutectic reaction of Al-Si binary alloy. High temperature and rapid solidification rate of molten pool, which are features of PTA process, enable the formation of high Si content alloyed layer with uniform distribution of fine primary Si paticle. High plasma arc current was beneficial to make the alloyed layer with smooth surface appearance in wide range of powder feeding rate, because enough volume of molten pool was necessary make alloyed layer. Uniform dispersion of fine primary Si particle with about 30${\mu}{\textrm}{m}$ in particle size can be obtained in layer with Si content ranging from 30 to 50 mass %. Hardness of alloyed layer increased with increasing Si content, but increasing rate of hardness differed with macrostructure of alloyed layer. Wear resistance of alloyed layer depended on $V_{si}$(volume fraction of primary Si) and was remarkably improved to two times of base metal at 20-30% $V_{si}$ without cracking, but no more improvement was obtained at larger $V_{si}$.