• 전자공학회논문지A
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• 제31A권10호
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• pp.87-93
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• 1994

Ohmic contacts between Au and p-HgHg_{0.7}Cd_{0.3}Te$ with low specific contact resistance have been obtained. The contact region of the wafer is first pre-heated for 5 seconds in a rapid thermal processing equipment. The temperature reaches a maximum value of about 200$^{\circ}C$ at the end of the 5 seconds. Next, a thin Au film is formed on the contact region by immersing the sample in AuCl$_{3}$ solution. the sample is then post-annealed in the same condition as the pre-heating after Pb/In pad metals are deposited on the electroless Au contacts. The specific contact resistance measured by transmission line model is 5${\times}10^{-3}{\Omega}cm^{2}$ at 80K. RBS and differential Hall measurement data suggest that the above low resistance ohmic contact is ascribed to surface traps and increased gold diffusion rate.

• Current Optics and Photonics
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• 제3권6호
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• pp.541-547
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• 2019

A novel photonic crystal fiber (PCF) sensor with three D-shaped holes based on surface plasmon resonance (SPR) is analyzed in this paper. Three D-shaped holes are filled with the analyte, and the gold film is deposited on the side of three planes. The design of D-shaped holes with outward expansion can effectively solve the uniformity problem of metallized nano-coating, it is beneficial to the filling of the analyte and is convenient for real-time measurement of the analyte. Compared with the hexagonal lattice structure, the triangular arrangement of the clad air holes can significantly reduce the transmission loss of light and improve the sensitivity of the sensor. The influences of the air hole diameter, the distance between D-shaped holes and core, and the counterclockwise rotation angle of D-shaped holes on sensing performance are studied. The simulation results show that the wavelength sensitivity of the designed sensor can be as high as 10100 nm/RIU and the resolution can reach 9.9 × 10^-6 RIU.

• 대한치과기공학회지
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• 제33권4호
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• pp.271-281
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• 2011

Purpose: The aim of this study is to investigate the changes in hardness and microstructure of a dental multipurpose alloy after simulated complete firing with controlled cooling rate and holding time by characterizing the changes in hardness and microstructure after simulated firing with various cooling rates and holding times. Methods: Before hardness testing, the specimens were solution treated and then were rapidly quenched into ice brine. The specimens were completely fired in furnace. Hardness measurements were made using a Vickers microhardness tester. The specimens were examined at 15 kV using a field emission scanning electron microscope. Results: The maximum hardness value was obtained at stage 0 after simulated firing with various cooling rates (quick cooling, stage 0, stage 1, stage 2, stage 3). By the repetitive firing, the hardness of the tested alloy decreased gradually. By holding the specimen at $500^{\circ}C$ for 10-20min after simulated firing, the hardness increased apparently. However, to hold the alloy for long periods of time in the relatively high temperature after simulated firing resulted in the formation of thick oxidation layer. The oxide film formed on the surface of the alloy after simulated complete firing with controlled cooling rate, which was mainly composed of O and Zn. Conclusion: It is reasonable to hold the alloy at $500^{\circ}C$ for 10-20min after complete firing in other to improve the final hardness of the alloy.

• 대한기계학회논문집B
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• 제21권4호
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• pp.579-588
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• 1997

The heat transfer and flow measurements from a convex curved surface to a circular impinging jet have been made. The flow at the nozzle exit has a fully developed velocity profile. The jet Reynolds number (Re) ranges from 11,000 to 50,000, the dimensionless nozzle-to-surface distance (L/d) from 2 to 10, and the dimensionless surface curvature (d/D) from 0.034 to 0.089. The results show that the stagnation point Nusselt number (N $u_{st}$ ) increases with increasing value of d/D. The maximum Nusselt number at the stagnation point occurs at L/d .ident. 6 to 8 for all Re's and d/D's tested. For larger L/d, N $u_{st}$ dependency on Re is stronger due to an increase of turbulence in the approaching jet as a result of the more active exchange of momentum with a surrounding air. The local Nusselt number decreases monotonically from its maximum value at the stagnation point. However, for L/d=2 and Re=23,000, and for L/d.leq.4 and Re=50,000, the stream wise Nusselt number distributions exhibit secondary maxima at r/d .ident. 2.2. The formation of the secondary maxima is attributed to an increase in the turbulence level resulting from the transition from a laminar to a turbulent boundary layer.ndary layer.

• 대한기계학회논문집B
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• 제23권6호
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• pp.734-743
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• 1999

The local Nusselt numbers have been measured for a round turbulent jet impinging on the concave surface with and without rib. Liquid crystal/transient method was used to determine the Nusselt number distributions along the surface. The temperature on the surface was measured using liquid crystal and a digital color image processing system. The experiments were made for the jet Reynolds number (Re) 23,000, the dimensionless nozzle-to-surface distance (L/d) from 4 to 10, the dimensionless surface curvature (d/D) 0.056, and the rib type (height ($d_1$) 0.2 cm, pitch (p) from 1.2 to 3.2 cm). It was founded that only when $L/d{\geq}6$, the average Nusselt numbers on the concave surface with rib are higher than those without rib, mainly due to an increase in the turbulent intensity caused by the effect of rib attached to the wall surface. It was realized that the rib attached to the concave surface may no longer enhance the heat transfer rate or even lowers it depending on the rib type and flow conditions. In addition, the results by the steady-state method using the gold-film Intrex were in good agreement with those by the transient shroud method.

• 복식문화연구
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• 제13권5호
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• pp.763-776
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• 2005

The purpose of this study is to analyze the glamour image in contemporary women's fashion since 1990. The method of study is to analyze the documentary and fashion magazines about the glamour images. Most of all, glamour has been composed by connection of hollywood film industry and fashion. Glamourous body image showed sensual, threatening and vague body. Formative characteristics in fashion showed a tight silhouette, neglige, lace look, dress showing neck and shoulder, fur coat, stiletto, diamond, gold, big and thick jewelry, satin, velvet, lace, mink and fox fur, etc. Internal meaning was a fantasy, ideal, wealth, fame, hyper-feminity, vagueness, vulgarity, sexuality, mystery, professional, fatalness, aggressiveness and evil. Since 1990, the glamour images in fashion were as follows; First, the glamour with hyper-feminity showed a classical femme-fatal image as fearful existence with a power more than allure. Second, the glamour with vulgarity showed an exaggerated, cheap and popular kitsch image, which have intense colors, lavish surfaces and excessive sexual signs. Third, the glamour with classical sensuality showed a hi-glamour image of hollywood actresses being active from 1930 to 1950, which was expressed glittery dress, stole, diamond, fur wrap, hill, luxury dress. Fourth, the glamour with sexual perversion showed an erotic, vague and sexual drag image, and fetish costume. Fetishistic elements were rubber, PVC, stiletto, thick and high boots and corset and particularly, they were a main method of expression of glamour image. Fifth, the glamour with future image showed a mechanical and mysterious image and it was a conscious style by metallic, plastic and sleeky fabric. In conclusion, glamour fashion image is an ideal beauty type of women and will exist as a meaningful aesthetic sign in women's fashion.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2014년도 제46회 동계 정기학술대회 초록집
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• pp.359-359
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• 2014

In this study, surface plasmon resonance structures for the selective and the enhanced transmission of infrared light were designed. In order to relieve the large discontinuity of refractive index between air and metal hole array, $Si_3N_4$ was used as the impedance matching layer. Experimental parameter were calculated and determined in advance by the rigorous coupled wave analysis (RCWA) simulation, and then the experiment was carried out. A 2-dimensional metal hole array structures were patterned on the size of $1{\times}1cm^2$ GaAs substrate using photolithography process, and 5 nm thick Ti, 50 nm thick Au were deposited by E-beam evaporator, respectively. Subsequently, $Si_3N_4$ films with various thicknesses (150, 350, 550, and 750 nm) were deposited by plasma enhanced chemical vapor deposition (PECVD). For the comparison, transmittance of specimens with and without $Si_3N_4$ was measured using Fourier transform infrared spectroscopy (FTIR) in the range of $2.5-15{\mu}m$. Furthermore, the surface and the cross-sectional images were collected from the specimens by scanning electron microscopy (SEM). From the results, it was demonstrated that the transmittance was enhanced up to 80% by the deposition of 750 nm $Si_3N_4$ at $6.23{\mu}m$. It has advantage of enhanced transmission despite the simple fabrication process.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2010년도 제39회 하계학술대회 초록집
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• pp.305-305
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• 2010

It is known that a pulse of electrons of high kinetic energy (1-3 eV) in metals can be generated with the deposition of external energy to the surface such as in the absorption of light or in exothermic chemical processes. These energetic electrons are not in thermal equilibrium with the metal atoms and are called "hot electrons" The concept of photon energy conversion to hot electron flow was suggested by Eric McFarland and Tang who directly measured the photocurrent on gold thin film of metal-semiconductor ($TiO_2$) Schottky diodes [1]. In order to utilize this scheme, we have fabricated metal-semiconductor Schottky diodes that are made of Pt or Au as a metallic layer, Si or $TiO_2$ as a semiconducting substrate. The Pt/$TiO_2$ and Pt/Si Schottky diodes are made by PECVD (Plasma Enhanced Chemical Vapor Deposition) for $SiO_2$, magnetron sputtering process for $TiO_2$, e-beam evaporation for metallic layers. Metal shadow mask is made for device alignment in device fabrication process. We measured photocurrent on Pt/n-Si diodes under AM1.5G. The incident photon to current conversion efficiency (IPCE) at different wavelengths was measured on the diodes. We also show that the steady-state flow of hot electrons generated from photon absorption can be directly probed with $Pt/TiO_2$ Schottky diodes [2]. We will discuss possible approaches to improve the efficiency of photon energy conversion.

• 대한기계학회논문집B
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• 제25권4호
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• pp.475-484
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• 2001

The purpose of this study is to investigate the heat transfer augmentation using the perforated plate placed in front of a target plate in an axisymmetric impinging air jet system. The new liquid crystal technique using neural networks with median filtering is used to determine the Nusselt number distributions on the target surface. The experiments were made for the jet Reynolds number (Re) 23,000. The effects of the pitch-to-diameter (p/d1) from 1.5 to 2.5 in the perforated plate, the hole diameter on perforated plate (d1) from 4㎜ to 12㎜, the perforated plate to target surface distance (z/d1) from 1 to 3, and the nozzle-to-target surface distance (L/d) from 2 to 10 on the heat transfer characteristics were experimentally investigated. It was found that when the perforated plate was located between the nozzle exit and the target plate, the average heat transfer rate at the stagnation region corresponding to r/d$\leq$1.0 was increased up to the maximum 2.3 times compared to the case without the perforated plate.

• 한국진공학회:학술대회논문집
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• 한국진공학회 2011년도 제40회 동계학술대회 초록집
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• pp.446-446
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• 2011

One dimensional (1-D) structures of ZnO nanorods are promising elements for future optoelectronic devices. However there are still many obstacles in fabricating high-quality p-type ZnO up to now. In addition, it is limited to measure the degree of the doping concentration and carrier transport of the doped 1-D ZnO with conventional methods such as Hall measurement. Here we demonstrate the measurement of the electronic properties of p- and n-doped ZnO nanorods by the Kelvin probe force microscopy (KPFM). Vertically aligned ZnO nanorods with intrinsic n-doped, As-doped p-type, and p-n junction were grown by vapor phase epitaxy (VPE). Individual nanowires were then transferred onto Au films deposited on Si substrates. The morphology and surface potentials were measured simultaneously by the KPFM. The work function of the individual nanorods was estimated by comparing with that of gold film as a reference, and the doping concentration of each ZnO nanorods was deduced. Our KPFM results show that the average work function difference between the p-type and n-type regions of p-n junction ZnO nanorod is about ~85meV. This value is in good agreement with the difference in the work function between As-doped p- and n-type ZnO nanorods (96meV) measured with the same conditions. This value is smaller than the expected values estimated from the energy band diagram. However it is explained in terms of surface state and surface band bending.