• 한국공작기계학회논문집
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• 제12권6호
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• pp.44-49
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• 2003

To obtain the surface roughness with range from 10nm to 1nm we need the study of ultra-precision machine, cutting condition, and materials. In this paper, the optimal cutting conditions for getting mirror surface of aluminum alloy have been examined experimentally by using ultra-precision turning machine and sing1e crystal diamond tool. In generally, the cutting conditions such as feed rate and depth of cut have effect on the surface roughness in ultra-precision turning. The result of surface roughness was measured by the ZYGO New View 200. Therefore, The surface roughness and cutting conditions has been clarified. The smooth surface of aluminum alloy less than 1nm RMS, 1nm Rmax can be obtained by the ultra-precision cutting.

• 한국결정성장학회지
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• 제7권2호
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• pp.315-323
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• 1997

수직승화방법을 이용하여 시료의 용융점 미만의 온도에서 CdS 단결정을 성장하였다. 분말법을 이용한 X-ray 실험으로부터 구한 CdS 단결정의 격자상수 값은 $a_0=4.139\AA$, $c_0=6.719\AA$이었다. 성장된 CdS 단결정과 CuCl 용액을 사용하여 $Cu_2$S/CdS 태양전지를 제작한 후 2분 동안 공기중에서 $250^{\circ}C$로 열처리한 후 light-to-dark J-V cross over effect를 측정하였다. 측정된 Voc, Jsc, Vop와 fill factor값은 각각 0.40 volt, $4.2mA/\textrm{cm}^2$, 0.31 volt,$3.8mA/\textrm{cm}^2$, 0.68이었으며, 효율은 3.8 %를 나타내었다. 제작된 태양전지의 spectral response는 광발광 실험으로부터 498 nm (2.49eV)와 585 nm (2.12 eV)에서 그 peak가 나타남을 확인하였다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.175-178
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• 2004

The stochiometric mixture of evaporating materials for the $ZnIn_2S_4$ single crystal thin film was prepared from horizontal furnace. To obtain the $ZnIn_2S_4$ single crystal thin film, $ZnIn_2S_4$ mixed crystal was deposited on throughly etched semi-insulating GaAs(100) in the Hot Wall Epitaxy(HWE) system. The source and substrate temperature were $610^{\circ}C$ and $450^{\circ}C$, respectively and the growth rate of the $ZnIn_2S_4$ sing1e crystal thin film was about $0.5\;{\mu}m/hr$. The crystalline structure of $ZnIn_2S_4$ single crystal thin film was investigated by photoluminescence and double crystal X-ray diffraction(DCXD) measurement. The carrier density and mobility of $ZnIn_2S_4$ single crystal thin film measured from Hall effect by van der Pauw method are $8.51{\times}10^{17}\;cm^{-3}$, $291\;cm^2/V{\cdot}s$ at $293_{\circ}\;K$, respectively. From the photocurrent spectrum by illumination of perpendicular light on the c - axis of the $ZnIn_2S_4$ single crystal thin film, we have found that the values of spin orbit splitting ${\Delta}S_O$ and the crystal field splitting ${\Delta}Cr$ were 0.0148 eV and 0.1678 eV at $10_{\circ}\; K$, respectively. From the photoluminescence measurement of $ZnIn_2S_4$ single crystal thin film, we observed free excition $(E_X)$ typically observed only in high quality crystal and neutral donor bound exciton $(D^{o},X)$ having very strong peak intensity The full width at half maximum and binding energy of neutral donor bound excition were 9 meV and 26 meV, respectively, The activation energy of impurity measured by Haynes rule was 130 meV.

• Journal of the Optical Society of Korea
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• 제19권1호
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• pp.63-68
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• 2015

A one-step fabrication of a photonic crystal (PC) with functional defects is demonstrated. Using multi-beam phase-controlled holographic lithography with a diffracting optical element, large area one dimensional (1D) and two dimensional (2D) PCs with periodic defects were fabricated. The uniform area is up to $2mm^2$, and tens of defect channels have been introduced in the 1D and 2D PC structure. This technique gives rise to substantial reduction in the fabrication complexity and significant improvement in the spatial accuracy of introducing functional defects in photonic crystals. This method can also be used to design and fabricate three dimensional (3D) PCs with periodic defects.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2004년도 추계학술대회 논문집 Vol.17
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• pp.671-674
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• 2004

BSCCO thin films have been fabricated by epitaxy growth at an ultra-low growth rate. The growth rates of the films was set in the region from 0.17 to 0.27 nm/min. MgO(100) was used as a substrate. In order to appreciate stable existing region of Bi 2212 phase with temperature and ozone pressure, the substrate temperature was varied between 655 and 820 $^{\circ}C$ and the highly condensed ozone gas pressure(PO3) in vacuum chamber was varied between $2.0{\times}10^{-6}$ and $2.3{\times}10^{-5}$ Torr. Bi 2212 phase appeared in the temperature range of 750 and 795 $^{\circ}C$ and single phase of Bi 2201 existed in the lower region than $785\;^{\circ}C$. Whereas, $PO_3$ dependance on structural formation was scarcely observed regardless of the pressure variation. And high quality of c-axis oriented Bi 2212 thin film with $T_c$(onset) of about 90 K and $T_c$(zero) of about 45 K is obtained. Only a small amount of CuO in some films was observed as impurity, and no impurity phase such as $CaCuO_2$ was observed in all of the obtained films.

• Progress in Superconductivity
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• 제4권1호
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• pp.14-18
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• 2002

We had succeeded to grow bulk sing1e crystals of La／sub 2-x／Sr／sub x／$CuO_4$by the traveling solvent floating zone method (TSFZ), and to prepare La／sub 2-x／Sr／sub x／CuO$_4$single-crystalline thick films on the Zn-doped La$_2$$CuO_4$ substrate by new liquid phase epitaxial technique using an infrared heating furnace (IR-LPE). In this paper, Ireview growth of bulk single crystals and single-crystalline thick films of La／sub 2-x／Sr／sub x／$CuO_4$, and discuss on their device properties to develop high speed integrated electronic devices.

• Bulletin of the Korean Chemical Society
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• 제22권1호
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• pp.59-62
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• 2001

The dried fruit-body of Daedaleopsis tricolor was extracted by the petroleum ether. The extracts were purified by liquid-liquid extraction, column chromatography, and recrystallization. The purified compound was a colorless orthorhombic crystal form. Its melting point, molecular weight and molar extinction coefficient $(\varepsilon)$ were estimated $168-170^{\circ}C$, 424 and 3,935 at 208 nm, respectively. Its structure was elucidated to be 20(29)-lupen-3-one by UV-Vis, FT-IR, NMR and X-ray crystallographic analysis. It showed antifungal activities against Saccharomyces cerevisiae and Microsporum gypseum, and antibacterial activities against Escherichia coli, Proteus vulgaris, Pseudomonas pyocyanea, Bacillus subtilis, and Staphylococcus aureus. In addition, this compound showed an antioxidative activity on lipid-peroxidation by 6.4%.

• 한국결정성장학회지
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• 제10권3호
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• pp.189-198
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• 2000

수평전기로에서 $CuGaSe_2$다결정을 합성하여 HWE(Hot Wall Epitaxy) 방법으로 $CuGaSe_2$단결정 박막을 반절연 성 GaAs(100)기판 위에 성장하였다. $CuGaSe_2$단결정박막은 증발원의 온도를 $610^{\circ}C$, 기판의 온도를 $450^{\circ}C$로 성장하였다. 이때 성장된 단결정 박막의 두께는 2.1$\mu\textrm{m}$였다. 단결정 박막의 결정성의 조사에서 20K에서 광발광(photoluminescence) 스펙트럼이 672.6nm(1.8432 eV)에서 exciton emission 스펙트럼이 가장 강하게 나타났으며, 또한 이중결정 X-선 요동곡선(DCRC)의 반폭치(FWHM)도 138 arcsec로 가장 작아 최적 성장 조건임을 알 수 있었다. Hall 효과는 van der Pauw 방법에 의해 측정되었으며, 온도에 의존하는 운반자 농도와 이동도는 293 K에서 각각 $4.87{\times}10^{23}$ electron/$m^{23}$ , $1.29{\times}10^{-2}$$\m^2$/v-s였다. $CuGaSe_2$ 단결정 박막의 광전류 단파장대 봉우리들로부터 20K에서 측정된 $\Delta$Cr(crystal field splitting)은 약 0.0900 eV $\Delta$So(spin orbit coupling)는0.2493 eV였다. 20K에서 광발광 봉우리의 667.6nm(1.8571 eV)는 free exciton($E_x$), 672.6nm(1.8432 eV)는 acceptor-bound exciton 인 $I_2$와 679.3nm(1.8251 eV)는 donor-bound exciton인 $I_1$였다. 또한 690.9nm(1.7945 eV)는 donor-acceptor pair(DAP) 발광 $P_0$이고 702.4nm(1.7651 eV)는 DAP-replica $P_1$, 715.0nm(1.7340 eV)는 DAP-replica $P_2$, 728.9nm(1.7009 eV)는 DAP-replica $P_3$, 741.9nm(1.6711 eV)는 DAP-replica $P_4$로 고찰된다. 912.4nm(1.3589 eV)는 self activated(SA)에 기인하는 광발광 봉우리로 고찰되었다.

• 한국산학기술학회논문지
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• 제8권2호
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• pp.207-211
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• 2007

본 논문에서는 단결정$(Al_2O_3)$ 성장을 DC-Motor로 제어하여 양질의 결정을 얻도록 하는 자동 가스 조절용 DC-Motor의 운영 시스템과 실시간 모니터링 시스템을 연구 개발하였다. 인조 보석류나 예물시계의 유리와 고열 내화용 투명유리 등에 사용되는 단결정(單結晶:$Al_2O_3$) 제품은 대부분의 가열 소성제품처럼 결정 성장 중에 로(爐)내의 열 흐름에 의해 제품의 품질과 특성에 결정적인 영향을 받게 된다. 따라서 수소와 산소를 적절히 혼합하여 로(爐) 내에서 연소시킴으로 공정시간 동안 로(爐)의 온도를 최적의 상태로 유지시키는 것이 양질의 단결정$(Al_2O_3)$을 제조하는 핵심 요소가 된다. 본 연구에서 수행한 가스 조정용 전동 밸브는 기존의 수작업으로 수행하던 압력 밸브의 제어를 기기 작동 밸브의 압력을 샘플링 하여 변위 값들을 일련의 명령어로 변환한 후 컴퓨터의 제어 신호로 바꾸어 밸브를 조정하도록 함으로서 직경이 확대된 단결정의 제조를 가능하게 하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 The 6th International Symposium of East Asian Resources Recycling Technology
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• pp.633-637
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• 2001

Oil fly ash is known as one source of raw materials from which vanadium and nickel metals can be recovered. The current recovery process of valuable metals from oil fly ash is mainly the hydrormetallurgy one. Nevertheless, a great amount about 50~80%, of unburned carbon remains as byproduct after hydrormetallursy process. In Taiwan, if hydrormetallursy processes have proceeded, it can be estimated that the annual production of unburned carbon is 25 thousand tons. From the viewpoint of resource recycling, this study is a preliminary study and investigates in recovery of sub micron- graphitized carbon from unburned carbon by a designed process. The designed process included the following steps: 1.selecting a portion with +400mesh size from unburned carbon; 2.treating the selected in ultrasonic waves; 3.using a 400mesh sieve to obtain the product which is under 400mesh; 4.Removal ash from the product. In regard to treatment by ultrasonic waves in the designed process, treating time of ultrasonic waves is a simple and only variance in this study. The results indicate that the production yields increase with the treating time of ultrasonic waves; the production yield in specific conditions of this study can reach about 23%, in which ash content in product is about 2.5%. According to results of SEM, TEM and XRD, the products from the designed process are flakes in shape, several microns in size and graphitized carbon in carbon crystal phase. Except to graphitized carbon, there are a little carbon blacks, which are graphite 2H in carbon crystal phase in the products. Conclusively, the designed process is possibly applicable, by which comes to the recovery of micron- graphitized carbon.