• Journal of Powder Materials
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• v.10 no.4
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• pp.241-248
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• 2003

Biaxially textured Ni tapes were fabricated by a cold working and recrystallization heat treatment processes from powder compact rods. The processing parameters associated with the cube texture formation in Ni tapes were systematically investigated by using X-ray diffraction and pole-figure analysis. The Ni powder used in this study was 5 $\mu$m in size and 99.99% in purity. To find the optimum sintering temperature, tensile tests were performed for Ni rods sintered at various temperatures. The Ni rods sintered at 100$0^{\circ}C$ showed poor elongation and low fracture strength, while the Wi rods sintered above 100$0^{\circ}C$ revealed good mechanical properties. The higher elongation and fracture strength of the Ni rods sintered at higher temperatures than 100$0^{\circ}C$ are attributed to the full densification of the sintered rods. The sintered Ni rods were cold-rolled with 5% reduction to the final thickness of 100 $\mu$m and then annealed for development of rube texture in rolled Ni tapes. The annealed Ni tapes depicted strong cube texture with FWHM(full-width at half-maximum) of in-plane and out-of-plane in the range of 8$^{\circ}$ to 10$^{\circ}$. The NiO deposited on the Ni tapes by MOCVD process showed good epitaxy with FWHM=10$^{\circ}$, which indicates that the Ni tapes can be used as a substrate for YBCO coated conductors.

• Journal of the Microelectronics and Packaging Society
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• v.15 no.2
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• pp.1-6
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• 2008

New devices with the structure of ITO/2-TNATA/NPB/TCTA/CBP:$7%Ir(ppy)_3$/BCP/SFC-137/LiF/Al were designed and fabricated to develop high efficiency green phosphorescent organic light emitting diodes and their electroluminescence properties were evaluated. Among the devices with different thicknesses of CBP in a range of $150{\AA}{\sim}350{\AA}$, the best luminance was obtained in the device with $300{\AA}$-thick CBP host. Nearly saturated current efficiencies indicates that the maximum efficiency value can be obtained with CBP thicknesses of $300{\AA}{\sim}350{\AA}$. The current density, luminance, and current efficiency of the PhOLED(phosphorescent organic light emitting diode) with $CBP(300{\AA}):7%Ir(ppy)_3-emissive$ layer at an applied voltage of 10V were $40mA/cm^2,\;10000cd/m^2$, and 25 cd/A, respectively. The maximum current efficiency was 40.5cd/A under the luminance of $160cd/m^2$. The peak wavelength and FWHM(full width at half maximum) in the electroluminescence spectral were 512nm and 60nm, respectively. The color coordinate was (0.28, 0.63) on the CIE (Commission Internationale de I'Eclairage) chart.

• Journal of Electrical Engineering and Technology
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• v.11 no.6
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• pp.1880-1885
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• 2016

This study aims to design a zonal lumen for parking garage LED lightings of a slim appearance and 20 W/2,000 lm capacity and to fabricate a lighting luminaire accordingly. The frame is of a one-dimensional bar type with a reverse V-shaped section, with LED chips arranged along both sides. To maximize the $60^{\circ}$ to $80^{\circ}$ zonal lumen, the geometric structure was designed with the apex of the reverse V-shaped section at $40^{\circ}$ and both sides at $70^{\circ}$. As for the LED light source, focusing lenses with narrower full-width half-maximum (FWHM) in luminous intensity were used. A ray-tracing simulation method was utilized for the zonal lumen simulation of the given structure. An actual hardware of luminaire based on the simulation results was fabricated and characterized. The suggested model is meant to develop LED lightings with a proper level of zonal lumen required in parking garages.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.07a
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• pp.848-850
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• 2001

In this work, we investigated on the white-colored ribbon fiber synthesized from GaN powder. We convinced the formation of monoclinic phase $\beta$-Ga$_2$O$_3$from the X-ray diffraction pattern on ribbon fiber. The 10 K PL spectrum consisted with the strong emission band caused by self-activated optical center at 3.464 eV with the full-width at half maximum of 48 meV and the impurity related emission bands. Through this work, the optical properties and the electrical conductivity of $\beta$-Ga$_2$O$_3$, it will be useful for the fabrication of optoelctronic devices operating in visible spectrum region.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.484-487
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• 2001

Amorphous carbon thin films were deposited using laser ablation technique on Si(100) substrates at different temperatures. In this study, effects of the substrate temperature on the properties of amorphous carbor, films were systematically investigated. The surface morphologic and structural properties of the films were studied by scanning electron microscopy (SEM) and raman spectroscope, respectively. With increasing of the substrate temperature, the surface morphologies were changed significantly. Moreover the intensity ratio of D-band and G-band and the full width at half maximum of these bands were dependent on substrate temperatures.

• KIEE International Transactions on Electrophysics and Applications
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• v.5C no.1
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• pp.39-43
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• 2005

We proposed a structure for a 1.55 ㎛ strained separate confinement heterostructure (SCH) multi- quantum well (MQW) superluminescent diode (SLD), having a tapered active region. SLD was fabricated through a two-step procedure: the first step being metal organic chemical vapor deposition (MOCVD) and the second-step being liquid phase epitaxy (LPE). We used a 15 laterally tilted stripe and window region to suppress the lasing action of the SLD. The performance of the SLD showed output power of 11 mW with no lasing under 200 mA pulse driving. The full-width at half-maximum was 42 nm at 200 mA, 25℃.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.37-39
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• 1996

A hydride vapor phase epitaxy (HVPE) method was performed to prepare the GaN thick-films on c-plane sapphire substrates. The full-width at half maximum of double crystal X-ray rocking curve from 350${\mu}{\textrm}{m}$ thick GaN was 576 arcsecond. The photo- luminescence spectrum measured (at room temperature) show the narrow bound exciton(I$_2$) line and weak donor-acceptor pair recombination peak, however, there was not observed deep donor-acceptor pare recombination indicate the GaN crystals prepared in this study are of high purity and high crystalline quality.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05b
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• pp.31-34
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• 2003

The sapphire wafers for blue light emitting devices were manufactured by the implementation of the surface machining technology based on micro-tribology. This process has been performed by chemical and mechanical polishing(CMP) process. The sapphire crystalline wafers were characterized by double crystal X-ray diffraction. The sample quality of sapphire crystalline wafer at surfaces has a full width at half maximum 89 arcses. The surfaces of sapphire wafers were mechanically affected by residual stress and surface default. Sapphire wafers's waveness has higher abrasion rate in the edge of the wafer than its center due to Newton's Ring interference.

• Journal of Magnetics
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• v.12 no.4
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• pp.141-143
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• 2007

We have fabricated (0001) oriented hexagonal $HoMnO_3$ thin films with thickness of 300 nm using Pulsed Laser Deposition (PLD) technique on $Pt(111)/Ti/SiO_2/Si$ substrates. The XRD $\theta-2\theta$ pattern shows only (0002), (0004), and (0008) reflection of a hexagonal phase, and the full width at half maximum (FWHM) of (0004) peak is under $1.6^{\circ}$. The chemical state of Mn from XPS spectra of the films reveals the presence of $Mn^{3+}$ only. The temperature dependence of dielectric constant shows a weak anomaly at magnetic $N\acute{e}el$ temperature $(T_N)$, which is about 70 K.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.28 no.1
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• pp.85-91
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• 2004

The sapphire wafers for blue light emitting devices were manufactured by the implementation of the surface machining technology based on micro-tribology. This process has been performed by chemical and mechanical polishing process. The sapphire crystalline wafers were characterized by double crystal X-ray diffraction. The sample quality of sapphire crystalline wafer at surfaces has a full width at half maximum of 89 arcsec. The surfaces of sapphire wafer were mechanically affected by residual stress during the polishing process. The wave pattern of optical interference of sapphire wafer implies higher abrasion rate in the edge of the wafer than its center from the Newton's ring.