• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.471-472
• /
• 2008

The properties of Al doped ZnO (AZO) thin flim for solar cells with various input currents were studied in this paper. Using facing target sputtering with 2wt.% AZO targets, TCO films were deposited on glass(corning 2948) substrate at room temperature. AZO thin films were deposited by 0.2A, 0.4A, 0.6A and 0.8A at the thickness of 300nm. Electrical, optical and structural of thin films investigated by a Hall effect measurement (Ecopia), an UV-VIS spectrometer(HP) and a X-ray diffractometer (Rigaku). As a results, all thin films showed transmittance about 80%, respectively and resistivity was $7.67\times10^{-4}\Omega$-cm at 0.6A.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2008.06a
• /
• pp.216-217
• /
• 2008

Zinc-oxide films were deposited by pulsed laser deposition (PLD) technique using doped ZnO target (mixed $In_2O_3$ 0.1, 0.3, 0.6 at. % - atomic percentage) on the p-type Si(111) substrate. A little Indium has added at the n-ZnO films for the electron concentration control and enhanced the electrical properties. Also, post thermal annealed ZnO films are shown an enhanced structural and controled electron concentration by the annealing condition for the hetero junction diode of a better emitting characteristics. The electrical and the diode characteristics of the ZnO films were investigated by using Hall effect measurement and current-voltage measurement.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 1998.06a
• /
• pp.67-70
• /
• 1998

In this work, the freestanding GaN single crystalline substrates without cracks were grown by hydride vapor phase epitaxy (HVPE). The GaN substrates, having a current maximum size of 350 $\mu\textrm{m}$-thickness and 10${\times}$10 $\textrm{mm}^2$ area, were obtained by HVPE growth GaN on sapphire substrate and subsequent mechanical removal of the sapphire substrate. A lattice constant of c$\_$0/=5.18486 ${\AA}$ and a FWHM of DCXRD was 650 arcsec for the single crystalline freestanding GaN substrate. The low temperature PL spectrum consist of excitonic emission and deep donor to acceptor pair recombination at 1.8 eV. The Raman E$_2$ (high) mode frequency was 567 cm$\^$-1/ which was the same as that of strain free bulk single crystals. The Hall mobility and carrier concentration was 283 $\textrm{cm}^2$/V$.$sec and 1.1${\times}$10$\^$18/ cm$\^$-3/, respectively. The freestanding and crack-free GaN single crystalline substrate suitable for the homoepitaxial growth of GaN, and the HVPE method are promising approaches for the preparation of large area, crack-free GaN substrates.

• Structural Engineering and Mechanics
• /
• v.17 no.5
• /
• pp.627-639
• /
• 2004

The objective of this research was to evaluate the performance of metal-plate-connected truss joints subjected to cyclic loading conditions that simulated seismic events in the lives of the joints. We also investigated the duration of load factor for these joints. We tested tension splice joints and heel joints from a standard 9.2-m Fink truss constructed from $38-{\times}89-mm$ Douglas-fir lumber: 10 tension splice joints for static condition and for each of 6 cyclic loading conditions (70 joints total) and 10 heel joints for static condition and for each of 3 cyclic loading conditions (40 joints total). We evaluated results by comparing the strengths of the control group (static) with those of the cyclic loading groups. None of the cyclic loading conditions showed any strength degradation; however, there was significant stiffness degradation for both types of joint. The results of this research show that the current duration of load factor of 1.6 for earthquake loading is adequate for these joints.

• Smart Structures and Systems
• /
• v.17 no.1
• /
• pp.17-29
• /
• 2016

Ultrasonic tomography is a powerful tool for identifying defects within an object or structure. But practical application of ultrasonic tomography to solids is often limited by time consuming transducer coupling. Air-coupled ultrasonic measurements may eliminate the coupling problem and allow for more rapid data collection and tomographic image construction. This research aims to integrate recent developments in air-coupled ultrasonic measurements with current tomography reconstruction routines to improve testing capability. The goal is to identify low velocity inclusions (air-filled voids and notches) within solids using constructed velocity images. Finite element analysis is used to simulate the experiment in order to determine efficient data collection schemes. Comparable air-coupled ultrasonic signals are then collected through homogeneous and isotropic solid (PVC polymer) samples. Volumetric (void) and planar (notch) inclusions within the samples are identified in the constructed velocity tomograms for a variety of transducer configurations. Although there is some distortion of the inclusions, the experimentally obtained tomograms accurately indicate their size and location. Reconstruction error values, defined as misidentification of the inclusion size and position, were in the range of 1.5-1.7%. Part 2 of this paper set will describe the application of this imaging technique to concrete that contains inclusions.

• Proceedings of the Korean Institute of Interior Design Conference
• /
• 2007.11a
• /
• pp.159-162
• /
• 2007

In the twentieth century, due to extraordinary development of companies and life style, etc, market environments to which companies around the world currently face are being changed with reflecting the current age in various fields, which result from globalization, digitalized innovation, diversity by information acceptance, an enhanced level of a consumer's consciousness, developed mass media, etc. The companies are trying to expand their sale areas, not only products but also their cultures, images, and brand power in the name of a 'marketing' in a space In other words, if companies and brands express some identities without considering an entire image evaluated by customers, a mis-positioning for the companies and the brands may be caused. In this case, the companies and brands may not influence on potential major customers at all, of an image for the companies and brands may be degrade Accordingly, a space marketing is required as a distinguished strategic means in characterizing identities according to brands. Also, a design for communicating the space marketing with the customers is required. Therefore, the purpose and effects of the present research are to analyze how identity characteristics for brands and company images are reflected by analyzing a faadeof a hall for housing cultures, and are to analyze how they are recognized by customer.

• Korean Institute of Interior Design Journal
• /
• v.26 no.1
• /
• pp.134-141
• /
• 2017

General hospitals in Korea have increased more in size since 2000, and as not only medical service but the quality of the environment also got important, the considerable changes have appeared revolving around the lobbies. This study is a basic research to find a direction of a plan for general hospital lobbies in response to the demands that change. It was examined the current condition of lobbies so as to derive the idea of types of lobbies and of functional elements, and based on the research, it was compared and analyzed in terms of the spatial configuration to draw the characteristics by type. The result of the research is as follows. (1) The lobbies were explored after being classified into four types; the plan(central type/street type) and the elevation(eclectic type/double-story type). (2) The hall and corridor were ranked high in order of importance in the whole spatial configuration, and it has been utilized in various ways. (3) Also, each type differed with the others in its main functional area, regarding traffic line efficiency and spatial intelligibility.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.06a
• /
• pp.55-56
• /
• 2007

The p-type ZnO thin film, fabricated by means of the ampoule-tube method, was used to make the ZnO p-n junction, and its characteristics was analyzed. The ampoule-tube method was used to make the p-type ZnO based on the As diffusion, and the hall measurement was used to confirm that the p-type is formed. the current-voltage characteristics of the ZnO p-n junction were measured to confirm the rectification characteristics of a typical p-n junction and the low leakage voltage characteristics. Using the ampoule-tube to fabricate the p-type ZnO will provide a very useful technology for producing the UV ZnO LED and ZnO-based devices.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2007.11a
• /
• pp.410-411
• /
• 2007

To investigate the ZnO LED which are interested in the next generation of short wavelength LEDs and Lasers, the ZnO thin films were deposited by RF magnetron sputtering system. The p-type ZnO thin film, fabricated by means of the ampoule-tube method, was used to make the ZnO p-n junction, and its characteristics was analyzed. The ampoule-tube method was used to make the p-type ZnO based on the As diffusion, and the hall measurement was used to confirm that the p-type is formed. the current-voltage characteristics of the ZnO p-n junction were measured to confirm the rectification characteristics of a typical p-n junction and the low leakage voltage characteristics. Analysis of ZnO LED V-I curve will provide a very useful technology for producing the UV ZnO LED and ZnO-based devices.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2004.07a
• /
• pp.263-266
• /
• 2004

The stochiometric mix of evaporating materials for the $ZnGa_2Se_4$ single crystal thin films were prepared from horizental furnace. The polycrystal structure obtaind from the power x-ray diffraction was defect chalcopyrite. The lattice costants $a_0\;and\;c_0\;were\;a_0=5.51\;A,\;c_0=10.98\;A$. To obtains the single crystal thin films, $ZnGa_2Se_4$ mixed crystal were deposited on throughly etched Si(100) by the Hot Wall Epitaxy (HWE) system. The temperates of the source and the substrate were $590^{\circ}C\;and\;450^{\circ}C$, respectively. The crystalline structure of single crystal thin films was investigated by the double crystal X-ray diffraction(DCXD). Hall effect on this sample was measured by the method of van der Pauw and studied on carrier density and mobility dependence on temperature. In order to explore the applicability as a photoconductive cell, we measured the sensitivity($\gamma$), the ratio of photocurrent to dark current(pc/dc), maximum allowable rower dissipation(MAPD), spectral response and response time.