• Journal of Powder Materials
• /
• v.6 no.2
• /
• pp.139-144
• /
• 1999

The pure Ti, Ni and carbon powders were reaction milled to synthesize the TiC-Ni based cermet powders with ultrafine microstructures. After milling, the ultrafine TiC or amorphous Ti-Ni phase was obtained, respectively, according to the milling condition. The effects of milling variables on the synthesizing behavior of the powders were investigated in detail. The sintered TiC-Ni based cermet of the reaction milled powders consisted of very fine TiC of 0.2~1.5$\mu$m, as compared with that of a commercial cermet of 3~5$\mu$m. This demonstrates the potenial of reaction milling as an effective processing route for the preparation of cermet materials.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
• /
• 2009.04a
• /
• pp.49-53
• /
• 2009

In this study, point gravity was measured to achieve terrestrid gravity data and the gravity is important element in precise geoid modelling. Surveys the relative gravity of 56 stations on 1st level route. In addition, it calculates gravity values, analysis gravity survey results using tidal correction, drift correction, datum-free adjustment. These point gravity data could be contribute in development of precise geoid model.

• 한국정보디스플레이학회:학술대회논문집
• /
• 2005.07a
• /
• pp.727-731
• /
• 2005

Design and manufacturing process of a full color LED microdislay fabricated by standard CMOS technology and containing an array of aluminum / nanostructured porous silicon reverse biased light emitting Schottky diodes will be discussed. Being of a solid state construction, this microdisplays are cost-effective, thin and light in weight due to very simple device architecture. Its benefits include also super high resolution, wide viewing angles, fast response time and wide operating temperature range. The advantages of full integration of an LED-array and driving circuitry onto a Si-chip will be also discussed.

• Journal of the Semiconductor & Display Technology
• /
• v.11 no.4
• /
• pp.7-12
• /
• 2012

Extrusion is one of the most important operations in the polymer-processing industry. Development of models for extrusion and computer tools offer a route to developing reliable and optimized process designs. The models are based on the analysis of physical phenomena encountered during the process. Balance equations for mass, momentum and energy are fundamental to the problem. A predictive computer model has been developed for the single screw extruders with conventional screws of different geometry. The model takes into account melting zones of the extruder and describes an operation of the extruder system, making it possible to predict mass flow rate of the polymer, pressure and velocity profiles along the extruder screw channel. The simulation parameters are the material and rheological properties of the polymer; the screw pitch, and screw speed.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.831-832
• /
• 2006

Solid-state processing via the bulk mechanical alloying enables us to directly fabricate $Mg_2X$ semi-conductive material performs. Precise control of chemical composition leads to investigation on the dilution and enrichment of X in $Mg_2X$. Two types of solid-state reactivity are introduced: e.g. synthesis of $Mg_2Si$ from elemental mixture Mg-Si is nucleation-controlled process while synthesis of $Mg_2Sn$ from Mg-Sn, diffusion-controlled process. Thermoelectricity of these $Mg_2X$ is evaluated for discussion on the validity and effectiveness of this new PM route as a reliable tool for fabrication of thermoelectric compounds.

• Proceedings of the Korean Powder Metallurgy Institute Conference
• /
• 2006.09b
• /
• pp.1290-1291
• /
• 2006

Fabrication of $Fe_3AlC$ matrix in-situ composite, reinforced by a FeAl phase, was studied by using the powder metallurgical processing route. Especially, in order to disperse the second phase more finely, we chose the mechanical alloying process. We investigated the microstructural and mechanical properties of the consolidated material. After consolidation by vacuum hot pressing, the compact showed almost full density and consisted of a $Fe_3AlC$ matrix and FeAl second phase (average particle size was less than 1m). The compact showed HV746, which was higher than that of the arc melted $Fe_3AlC$ monolithic material, HV603.

• Journal of the Korean Ceramic Society
• /
• v.25 no.2
• /
• pp.154-160
• /
• 1988

Almost single phase of Y1Ba2Cu3Ox, which exhibits the onset of superconducting transition at 90K, has been prepared via a conventional ceramic processing route followed by an anneal for a period of 10 hours at 45$0^{\circ}C$ in an atmosphere of 100% O2. The mean value for the oxygen content has been determined as x=6.85$\pm$0.02 by an iodometric titration technique. X-ray photoemission spectra are found to be consistent with a mixture of the d8(Cu3+) and d9(Cu2+) as the ground state and reveals that the local concentration of Cu3+ decreases with depth from the surface where x corresponds to 7.0. This is explained as being associated with the intercalation of oxygen during cooling from the annealing temperature.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.10
• /
• pp.3735-3737
• /
• 2011

We report a simple method for fabricating ZnO gas sensors via a sonochemical route and their $H_2$ gas sensing properties. Vertically aligned ZnO nanorod arrays as a sensing material were synthesized on a Pt-electrode patterned alumina substrate under ambient conditions. The advantage of the proposed method is a high speed of processing. The gas sensor based on ZnO nanorod arrays with large specific surface area showed a high response to $H_2$ and a detection limit of 70 ppm at $250^{\circ}C$. Also, their response and recovery time were relatively short and a complete regeneration was observed. A mechanism for sensing $H_2$ gas on the surface of ZnO nanorods is proposed.

• Journal of the Korea Safety Management & Science
• /
• v.9 no.5
• /
• pp.97-101
• /
• 2007

As the use of vehicle route application and LBS(location based service) are fast grew, the importance of maintaining road network data is also increased. To maintain road data accuracy, we can collect road data by driving real roads with probe vehicle, or using digital image processing for the extraction of roads from aerial imagery. After compare the new road data to current database, we can update the road database, but that job is mostly time and money consuming or can be inaccurate. In this paper, an updating method of using GPS(global positioning system) enabled cell phone is proposed. By using GPS phone, we can update road database easily and sufficiently accurately.

• Transactions of Materials Processing
• /
• v.11 no.6
• /
• pp.519-528
• /
• 2002

The microstructural evolution during the equal channel angular pressing of Ti-6Al-4V alloy was investigated using the transmission electron microscopy (TEM). ECA pressing was carried out isothermally with route C at $600^{\circ}C$ for two types of initial microstructure, i.e., equiaxed and Widmanstatten microstructures. At an initial stage of ECA pressing, the equiaxed microstructure showed more uniform flow than the Widmanstatten microstructure. However, both microstructures were significantly refined revealing nearly equiaxed grains of 0.3$mu extrm{m}$ in diameter with high angle grain boundaries after 4 passes of ECA pressing. These ultrafine gains were found to be stable with little grain growth, when annealed up to $600^{\circ}C$ for 1hr.