• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.2
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• pp.508-511
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• 2005

In the near future various new services will be created by using ubiquitous computing and ubiquitous network. Especially u-LBS(Ubiquitous Location Based Services) is recognized as one of the most important services. U-LBS is based on the data created by recognizing objects including both human and matters at any time and anywhere. Many researches related with object locating method by using RF are in the process of studying However there are few researches on the location of objects. In this paper we propose the recognition method of the location of objects by using RF and USN technology. In detail, the strength of RF signal is used to recognize the location of objects. Also we discuss about the future work to enhance the recognition rate of location by using a number of conditions including the weather, temperature etc. And Genetic Algorithm is used to get the optimal parameters with which we can get the more exact recognition rate of location.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.18 no.9
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• pp.2298-2306
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• 2014

In this paper, we propose an open loop power control algorithm to control transmission power of the On-The-Move(OTM) Satcom terminal in GEO satellite communication environment. The proposed algorithm identifies the current channel state restricted by an obstacle or an antenna depointing loss based on the received beacon signal strength. On the basis of the determined signal attenuation causes, the OTM Satcom terminal turns off the RF output when an antenna tracking is failed. If the OTM Satcom terminal experiences a channel blockage by an obstacle, the terminal spreads the transmit data to increase data reception probability. To evaluate the performance of the proposed algorithm, we compare an adjacent satellite interference level and an outage probability. The results show the performance of the proposed algorithm is better than that of the conventional algorithm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.4
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• pp.656-663
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• 2018

As the virtual reality technology, which has been attracting attention recently in the era of the fourth industrial revolution, is spreading and spreading throughout the society, expectation about virtual reality is gradually increasing. The major big companies such as Samsung and LG in Korea are concentrating on R &D and early ecosystem composition of virtual reality field as well as large global corporations such as Google and Facebook. But in Korea, the environment is not well equipped to compete with the global market and although there are many SMEs and start-up companies related to virtual reality, there are few successful companies. In this study, we analyze the domestic and foreign virtual reality market and industry and present ways of activation on virtual reality industry. We analysis by PEST analysis, SWAT and competitive structure analysis.Based on the analyzed results, ways to revitalize the virtual reality industry are suggested in this paper.

• Transactions on Electrical and Electronic Materials
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• v.1 no.4
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• pp.1-6
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• 2000

The mechanical strength of silicon carbide dose nor permit the use of diffusion as a means to achieve selective doping as required by most electronic devices. While epitaxial layers may be doped during growth, ion implantation is needed to define such regions as drain and source wells, junction isolation regions, and so on. Ion activation without an annealing cap results in serious crystal damage as these activation processes must be carried out at temperatures on the order of 1600$^{\circ}C$. Ion implanted silicon carbide that is annealed in either a vacuum or argon environment usually results in a surface morphology that is highly irregular due to the out diffusion of Si atoms. We have developed and report a successful process of using silicon overpressure, provided by silane in a CAD reactor during the anneal, to prevent the destruction of the silicon carbide surface, This process has proved to be robust and has resulted in ion activation at a annealing temperature of 1600$^{\circ}C$ without degradation of the crystal surface as determined by AFM and RBS. In addition XPS was used to look at the surface and near surface chemical states for annealing temperatures of up to 1700$^{\circ}C$. The surface and near surface regions to approximately 6 nm in depth was observed to contain no free silicon or other impurities thus indicating that the process developed results in an atomically clean SiC surface and near surface region within the detection limits of the instrument(${\pm}$1 at %).

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.5
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• pp.59-66
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• 2013

Because ordinary concrete cannot be hardened well under sub-zero temperatures, anti-freeze agents are typically added to prevent the frost damage and to ensure the proper hardening of concrete. With the advantage of a rapid exothermic reaction property, jet set concrete may be used as a cold weather concrete because it can reach the required strength before being damaged by cold weather. Recent studies are reported that magnesia-phosphate composites can be hardened very quickly and hydrated even in low temperature, which can be used as an alternative of severe cold weather concrete in arctic regions. This study developed the magnesia-phosphate composites that can be used in severe cold regions and suggested an appropriate mixture design from the experimental results.

• Journal of the Korean Institute of Gas
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• v.2 no.2
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• pp.34-39
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• 1998

Demand of the clean and convenient natural gas has continuously increased with recognizing of the environment problem since liquefied natural gas was introduced in Korea. Clean fuel natural gas was supplied to each city through high tensile strength pipeline connected by welding. Grades of pipeline were divided into the high and middle pressure according to supply pressure. Pipeline was welded mainly SMA welding process due to its easy handling, the other welding process was adopted according to the constructing condition. We were examined on the microstructure variation and mechanical properties of weld metal for high pressure pipeline, API 5L X-42.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.33 no.3
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• pp.107-113
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• 2005

A calorimeter of 2-ton thrust level rocket engine chamber has been developed to measure the wall heat flux. The liner of the chamber is made of copper-chromium alloy to maximize the heat transfer performance and structural strength. 1-D design code based on empirical correlations has been used for the prediction of the global thermal characteristics while 3-D CFD has been applied for the verification of local cooling performance. The predicted average wall heat flux at the throat is 43 $MW/m^{2}$ for the combustion chamber pressure of 53 bar. The chamber structure is confirmed to be safe at the pressure of 150 bar through 2-D stress analysis and measurement of the strain of the test species. Finally, the test of pressurizing the calorimeter chamber has been performed with water at the pressure of 150 bar in room temperature environment. No thermal damage has been detected after the hot-fire test in the test nozzle of same cooling performance with the developed calorimeter though the measured throat heat flux is higher than the design value by 10%.

• Journal of the Society of Disaster Information
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• v.8 no.4
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• pp.391-400
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• 2012

Recently, the construction industry commonly uses FRP as a reinforcement material because of its material advantages. FRP attached reinforcement has various advantages such as high strength, stiffness, excellent durability and construction practicability comparing to its weight. However, external attachment of FRP is water-tighted with low water permeable material, not draining water, probably causing damages on a permanent structure. The study manufactured it through pultrusion and examined GP(glass fiber panel) of which material-mechanical properties are almost same as the existing FRP but durability and attachment performance are better by stationary experiments, testing load-deflection curve, destruction types and load-deflection relation under repetitive loading test. As a result of 2,000,000 fatigue tests, it did not result in the destruction and showed excellent permanent attachment and durability as it displays significantly low compressive strain of concrete.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.8 no.2
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• pp.107-113
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• 2010

In this study, the adsorption reactions in the binary component system such as kaolinite-humic acid, kaolinite-americium and humic acid-americium were investigated. After performing the basic physico-chemical properties of the kaolinite, the adsorption reactions of the humic acid on the kaolinite were carried out with varying concentration of humic acid and ion strength, and pH. With increasing HA concentration and pH, the sorption of HA onto KA decreased, while the sorption of HA onto KA increased with increasing ionic stre ngth. Also, with varying pH, the adsorption reactions of the americium-kaolinite and americium-humic acid were studied. In the acid and neutral region, Am easily adsorbed on the HA, while the sorption of Am on the HA in the alkali region decreased because of electrostatic repulsion. The results from these studies make it possible to understand the characteristics of adsorption behaviour of the americium by the humic acid in the water environment.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.41 no.3
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• pp.66-70
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• 2009

Paper cultural heritages usually experienced the chemical and the physical deterioration because of various factors including preservation environment and the property of their materials. General restoration technology for paper cultural heritages is the lining. The application of the lining paper and the lining technology has varied depending on researcher's experiences. Therefore, each lining material and technology must be evaluated to develop a standard guide for preservation and restoration of paper cultural heritages. To date, various analysis techniques using lining paper, in terms of their materials, have been applied to analyses of causes and condition of damages, but it is difficult to develop a standard restoration treatment method of paper cultural heritages because it varies by their material. The Hanf, is made frrr the mulberry, is generally used for the lining in Korea.edt is required that the cr, in terms properties and general properties of Hanf, is used for lining papers, are evaluated to develop a standard guide for their restoration.ed this study, the general properties of several lining papers(Hanf), especially dimensave bility, were evaluated as part of the standardization of lining papers. The result have varied depending on the pulping chemical and the manufacturers. the basis weight, thickness and tensale strength of lining papers is bigger the paper treated by natural ash than the paper treated by sodium carbonate.ed case of formation, folding endurance, and dimensave bility, the paper treated by sodium carbonate showed better properties than those of the paper treated by natural ash.