• Proceedings of the Optical Society of Korea Conference
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• 1991.06a
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• pp.190-193
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• 1991

The monolithically integrated receiver OEIC using InGaAs/InP PIN PD, junction FET's and bias resistor has been fabricated on semi-insulating InP substrate. The fabrication process is highly compatible between PD and self-aligned JFET, and reduction in gate length is achieved using an anisotropic selective etching and a non-planar OMVPE process. The PIN photodetector with a 80 ${\mu}{\textrm}{m}$ diameter exhibits current of less than 5 nA and a capacitance of about 0.35 pF at -5 V bias voltage. An extrinsic transconductance and a gate-source capacitance of the JFET with 4 ${\mu}{\textrm}{m}$ gate length (gate width = 150 ${\mu}{\textrm}{m}$) are typically 45 mS/mm and 0.67 pF at 0 V, respectively. A voltage gain of the pre-amplifier is 5.5.

• Journal of the Korean institute of surface engineering
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• v.32 no.3
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• pp.303-306
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• 1999

On the effect of substrate bias at first stage of diamond synthesis at lower substrate temperature(approximately 673K) using microwave plasma CVD and effect of reaction gas system for the bias enhanced nucleation were studied. The reaction gas was mixture of methane and hydrogen or carbon monoxide and hydrogen. The nucleation density of applied bias -150V using $CH_4-H_2$ reaction gas system, significantly higher than that of $C-H_2$ reaction gas system. When the $CH_4-H_2$ reaction was used, nucleation density was increased because of existence of SiC as a interface for diamond nucleation. By use of this negative bias effect for fabrication of CVD diamond film using two-step diamond growth without pre-treatment, fabrication of the diamond film consist of diamond grains $0.2\mu\textrm{m}$ in diameter was demonstrated

• Transactions of Materials Processing
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• v.15 no.7 s.88
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• pp.496-503
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• 2006

The inner and outer car panels for bonnet, door, and trunk lid are assembled by hemming rather than welding. To achieve successful fabrication of these panels, the complicated timing chart of hemming units for pre-and main hemming stages should be made to optimal one. In this study, a design system for automatic timing chart generation is developed. Using AutoCAD VBA and EXCEL data chart, hemming die design parameters and guidelines were put into the program to give hemming unit drawings and consequent timing charts. Then the prepared timing charts were checked and modified. The effectiveness of the system is verified by applying it successfully to hemming unit design for bonnet panel joining.

• Journal of Ocean Engineering and Technology
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• v.17 no.6
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• pp.65-71
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• 2003

Since the preflex beam is fabricated through welding, the pre-compressive stresses that should occur over the concrete pier are diminished by the welding residual stresses. Therefore welding residual stresses must be relieved during the fabrication. Therefore, the analysis and examination of the accurate welding residual stress distribution characteristics are necessary. In this study, accurate distribution of welding residual stress of the preflex beam is analyzed by the finite element method, using 2 dimensional and 3 dimensional elements. Further, the thermo-mechanical behavior of the preflex beam is also studied. After the finite element analysis, real distribution of welding residual stress is measured using the sectioning method, and then is compared with the simulation results. The distribution of welding residual stress by finite analysis agreed well with the experimental results.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.1
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• pp.94-100
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• 2009

This paper proposes a novel curved shape piezoelectric unimorph using a new fabrication method. Instead of using thermal coefficient mismatch, which has been used for conventional processes for curved shape unimorphs, we used pre-stressed substrates and the room temperature adhesion process. A difference of the mechanical strains between the substrate and the piezoelectric layer makes the final manufactured unimorph get curved. Several performance tests of the proposed unimorph actuators were accomplished and the test results showed the proposed unimorph actuator got comparable actuation capability compared with conventional curved shape actuators.

• Journal of the Korea Furniture Society
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• v.16 no.2 s.30
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• pp.67-76
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• 2005

Bauhaus, founded in Weimar, Germany in 1919, represented Modernism which is proven in the field of art as well as architecture. Furthermore, in design field, Bauhaus is the essential historical event whose influence continues in contemporary design. Bauhaus furniture is simple and austere and has linear shapes which are suitable for mass production. Bauhaus developed functional furniture design such as knock-down and pre-fabricated furniture. In terms of finishes, Bauhaus furniture epitomizes the influence of De Stijl which used either achromatic colors and three primary colors or natural finishes of wood. Bauhaus contributed to furniture design field as below. 1. Success in mass-produced furniture through standardization and pre-fabrication 2. Pioneered on industrialization through collaboration between academia and industry 3. played essential role developing modem furniture by using not only metal but also such diverse materials as plywood, glass, and leather

• Proceedings of the Korea Institute of Applied Superconductivity and Cryogenics Conference
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• 2003.02a
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• pp.105-108
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• 2003

Long length of Bi-2223 superconducting wires were fabricated by stacking, drawing process with different precursor owders and different heat-treatment histories. The precursor powders were 2 kinds of Pb content. And a part of the tapes were experienced pre-annealing process which caused tetragonal structure of Bi-2212 phase to orthorhombic structure of it was during drawing process. We confirmed the transformation of Bi-2212 phase from tetragonal structure to orthorhombic structure and reduction of second phases. We designed and made a continuous Ic measurement system for Bi-2223/Ag HTS tape. We could achieve best Ic of 65 A at the Bi-2223/Ag tape using low Pb content of precursor powder and experienced pre-annealing process.

• Journal of Ocean Engineering and Technology
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• v.18 no.2
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• pp.52-57
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• 2004

Preflex beam is a method of construction designed to hold the pre-compressive stresses over the concrete pier by the preflexion load. During the fabrication of the girder, welding causes residual stresses. The welding residual stresses must be relieved in order to generate the accurate compressive pre-stresses. In this study, to determine the thermal distribution characteristics on the girder by welding, both three-dimensional finite element analysis and two-dimensional finite element analysis, in a quasi-steady state, is carried out. After comparing each result between the three-dimensional analysis and the two-dimensional analysis, finite element analysis is carried out against the actual girder, and the welding thermal distribution characteristic over the preflex beam is analyzed. It is possible to provide the input data for the analysis of the welding residual stresses.

• Journal of the Korean Ceramic Society
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• v.37 no.3
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• pp.280-287
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• 2000

Adsorption behavior and amount of phenolic resin followed silica (SiO2) formation onto silicon nitride(Si3N4) surface were investigated using electrokinetic sonic amplitude (ESA) technique and with UV spectrometer, to fabricate Si3N4/SiC nano-composite based on reaction between SiO2 formed and phenolic resin absorbed onto Si3N4 particle. The amount of SiO2 formed and carbon from phenolic resin absorbed onto Si3N4 surface were calculated quantitatively to adjust the reaction between SiO2 and phenolic resin, resulting in no residual SiO2 and carbon. As a result, pre-heated tempeature for optimized reaction was below 25$0^{\circ}C$, in which there was no residual SiO2 and carbon.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2002.10a
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• pp.323-328
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• 2002

Since the pre flex beam is fabricated by welding, the precompressive stresses that should occur over the concrete pier are diminished by the welding residual stresses. Therefore the welding residual stresses must be relieved during the fabrication. So the analysis and examination of the accurate welding residual stress distribution characteristic are necessary. On this study, accurate distribution of welding residual stress of preflex beam is analyzed by finite element method.