• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.217-220
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• 2008

A modified FRP-concrete composite deck applicable to cable stayed bridge with long girder-to-girder span is proposed, and its design and economical efficiency are presented. The existing FRP-concrete composite deck has low section stiffness due to adoption of GFRP panel with low elastic modulus, which arrives at difficulty in meet of serviceability limit such as deck deflection. So a new-type FRP-concrete composite deck, named precast FRP-concrete deck, is developed by extensioning concrete at the both ends of FRP-concrete composite deck, which brings the effect of reduction of net span length of deck. Compared to the existing FRP-concrete composite deck this modified deck has the advantage of increasing span length but slightly increases self weight. For this type of deck the section optimization is carried out for the cases of simply supported on girder and composite to girder. The optimized deck was applied to cable stayed bridge with a center span length of 540m, and as a result it is verified that PFC deck can be applied efficiently to cable stayed bridge due to reduction of quantity of upper structure.

• The Journal of the Korea Contents Association
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• v.10 no.5
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• pp.229-240
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• 2010

Most of all researchs and analyses in the field of television industry of Korea were related to Cable Television SO(System Operator), but few about PP(Program Provider) from the viewpoint of Industrial Theory in Korea. However, there wasn't a comprehensive research analysis in terms of the co-relationship of the market structure, market conduct and market performance of PP. This research analyzes co-relationship and dynamics of the market structure of PP, its market conduct and market performance in a comprehensive way in Cable TV industry. Especially this paper focuses on the analysis of 1)relationship and its influence between market structure and market conduct, 2) relationship and its influence between their market conducts and market performances and 3) relationship and its influence between market structure and market performance among 40 commercial PPs in terms of the theory of Industrial Organization in Korea. This paper is delated and reported as follows in conclusion : 1)the type of horizontal integration has an effect on the price and scale in the relationship between the structure and its conduct. 2)the price has effect on the revenue and viewing rate between the conduct and performance. And high dependency of the Cable TV license fee has an effect on viewing rate and revenue per subscribers(ARPU) between the conduct and performance. 3)The horizontal integration between the structure and performance had a positive effect on viewing rate and its product differentiation has an effect on the revenue per subscribers. Net cost of the product had a negative effect on the rate of profit.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.16 no.1
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• pp.1-15
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• 1980

An underwater recording system was designed to measure the sound spectra of the underwater noises produced by fishing gears in operation. Recorded were noi~es from three types of fishing gears: an anchovy set net, three anchovy boat seine net and a stern trawlnet. Acoustic analysis were made using a heterodyne analyzer, a digital frequency analyzer and a level recorder. The no;'e produced by the anchovy set net was found in the high frequency region of the onset of ambient noise spectrum with a slope of - 6 dB/octave. Here the ambient noise spectrum is higher, though similar in shape, than Knudsen spectrum, and is attributed to the breaking action of the coastal wave. Measured noise spectra during the fishing operations of the anchovy boat seine nets are attributed to the background noise of the sea in the presence of the fishing vessels. The frequency distribution of the noise was 20~5, 000 Hz in the case of two steel anchovy boat seiners, and 20-3,000 Hz in the case of the wooden anchovy boat seiner. The predominant frequency range was 250~350 Hz and maximum sound pressure level was 122 dB (re $1\muPa$) in the case of the steel boat and ] 17 dB in the case of the wooden boat. The noises produced by the trawl fishing gears are remarkably higher than the background noi~e in the presence of the fishing vessel. The frequency distribution of the noi~e was 20-6,300 Hz. The predominant frequency range was 100~200 Hz and maximum sound pressure level was 137 dB ( re $1\muPa$) . The noise spectra were not so much different from that caused by vibrations of the towing cable and the structure of the ground rope of the trawl net towed in an experimental tank.

• Proceeding of KASS Symposium
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• 2008.05a
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• pp.15-18
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• 2008

A Spatial structure, having a curvature with a curved surface, is an extremely efficient mechanical creation considering the external load. It is resisted the out-of-plane direction load by in-plane forces using the structure's curvature. Spatial Structures include many types of structures, such as: space frames or grids; cable-and-strut and tensegrity; air-supported or air-inflated; self-erecting and deployable; cable net; tension membrane; lightweight geodesic domes; folded plates; and thin shells. Membrane structures, a kind of lightweight soft structural system, are used for spatial structures. It is very important that effects by wind load than seismic and dead load. And, wind load is different by surrounding and shape of building In this study, we analyze the results of design wind load and wind tunnel tests about the 2 stadiums which are constructed on sensitive sites by effect of wind loads.

• Korean Journal of Metals and Materials
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• v.47 no.6
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• pp.338-343
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• 2009

The purpose of this study is to make the tantalum powder for solid electrolyte capacitor with SHS (self-propagating high-temperature synthesis) process. Raw materials for manufacturing Ta powder were used $Ta_{2}O_{5}$, Mg and NaCl. While progressing SHS process, $Ta_{2}O_{5}$ powder was reduced by Mg powder. The combustion temperature and velocity were easily controled by the varying mole ratio of NaCl, Mg and initial reaction pressure. In the case of only using NaCl as an inorganic agent, the shape is unagglomerated and has high surface area. whereas we were given the powder which has good net structure by the addition of excessive Mg as a diluent.

• Structural Engineering and Mechanics
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• v.62 no.6
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• pp.749-758
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• 2017

In structural mechanics, traditional analyses methods usually employ matrix operations for obtaining displacement and internal forces of the structure under the external effects, such as distributed loads, earthquake or wind excitations, and temperature changing inter alia. These matrices are derived from the well-known principle of mechanics called minimum potential energy. According to this principle, a system can be in the equilibrium state only in case when the total potential energy of system is minimum. A close examination of the expression of the well-known equilibrium condition for linear problems, $P=K{\Delta}$, where P is the load vector, K is the stiffness matrix and ${\Delta}$ is the displacement vector, it is seen that, basically this principle searches the displacement set (or deformed shape) for a system that minimizes the total potential energy of it. Instead of using mathematical operations used in the conventional methods, with a different formulation, meta-heuristic algorithms can also be used for solving this minimization problem by defining total potential energy as objective function and displacements as design variables. Based on this idea the technique called Total Potential Optimization using Meta-heuristic Algorithms (TPO/MA) is proposed. The method has been successfully applied for linear and non-linear analyses of trusses and truss-like structures, and the results have shown that the approach is much more successful than conventional methods, especially for analyses of non-linear systems. In this study, the application of TPO/MA, with Harmony Search as the selected meta-heuristic algorithm, to cables net system is presented. The results have shown that the method is robust, powerful and accurate.