• Steel and Composite Structures
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• v.18 no.2
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• pp.395-408
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• 2015

The paper considers the free vibration analysis of FGM grid systems. Up to now, very little work has been done on this type of system and the paper aspires to fill this gap. Based on the hybrid-stress finite element formulation free vibration solutions for FGM grid systems of various aspect ratios, different types of gradations functions, and support conditions are determined. The tabulation of these results, not available thus far, should be useful to designers and researchers who may use them.

• Asia pacific journal of information systems
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• v.13 no.3
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• pp.85-106
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• 2003

Recently, firms which have offered a "free Internet service" to their customers, are considering a "charged Internet service" for increasing a company's profit. But they have doubts about the results, because consumers may fly away from their web-site easily and may discontinue using their services. The purpose of this study is to investigate which factors make consumers use the charged Internet services. To do this, the factors, which are ease of using the service, usefulness of the service, the reputation of the service provider, service cost, and the intention to use the service as a mediator, are analyzed. To achieve this research objective, a structural equation model was constructed and a field study method was used. The findings are summarized as follows: First, ease of using the service, usefulness of the service, and service cost have significant impacts on the charged Internet service usage through the intention to use. Especially, although service cost influences on the service usage largely, the usefulness of the service has a bigger impact on the charged Internet service usage than service cost. Second, the reputation of the service provider does not have any impact on the service usage. Third, consumers using only the free Internet service tend to hesitate about using the "charged Internet service" because they doubt its ease of use and usefulness in spite of the service cost.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.19 no.4
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• pp.813-818
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• 2015

In this paper, WiMedia Distributed-MAC protocol is adopted for development of a seamless N-screen wireless service. Furthermore, to provide the OSMU (One Source Multi Use) N-screen service through P2P streaming in the seamless D-MAC protocol, a new Multicast-free DRP Availability IE is proposed and analyzed. In this Multicast-free DRP Availability IE, indicating Multicast DRP Owner and Receiver is required. The ACK frame transmissions are not required for Multicast transmissions in P2P N-screen services. Using this property, the Multicast-free DRP Availability IE scheme is proposed to expand the number of time slots available for unicast and multicast DRP reservations. Simulation results show that our Multicast scheme enhances performances in vewpoints of DRP reservation conflict and throughput.

• Asian-Australasian Journal of Animal Sciences
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• v.25 no.8
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• pp.1138-1144
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• 2012

This study was conducted to evaluate the efficacy of the dipeptide form of phenylalanine as a new source of amino acid in terms of growth performance and whole-body amino acid composition in comparison to the free form for red seabream (Pagrus major). Fish ($1.46{\pm}0.001g$) were fed four isonitrogenous and isocaloric experimental diets containing 0.7 or 1.4% phenylalanine either in free or dipeptide form. A feeding trial was carried out in three replicates and the fish were fed to apparent satiation for six weeks. At the end of the feeding trial, feed intake of fish was influenced by both phenylalanine form and level and significantly higher values were obtained at an inclusion level of 0.7% and by the use of dipeptide form. However, the other growth parameters did not significantly differ among treatments. Whole-body amino acid compositions revealed no significant changes in concentrations of both essential and non-essential amino acids regardless of the increase in phenylalanine levels or the use of its different forms. The finding in this study indicates that juvenile red seabream can utilize dipeptide phenylalanine as efficiently as free form without any undesirable effects on growth performance or whole-body amino acid composition.

• Proceedings of the Korean Magnestics Society Conference
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• 2013.12a
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• pp.95-95
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• 2013

The NdFeB magnet can be classified into the sintered magnet and bonded magnet. The former has superior magnet characteristics but the degree of freedom in shape is highly restricted, whereas the latter has a high degree of freedom, but its magnet characteristics are inferior to the former. When a NdFeB magnet is used at the elevated temperature, part of Nd must be replaced with a high priced Dy to increase its coercive force. For these reasons, a Dy free and high performance NdFeB bonded magnet is desired strongly. The author successfully developed a Dy free NdFeB anisotropic bonded magnet based on discovery of new phenomena called as d-HDDR reaction and its mass production process such as a thermally balanced hydrogen reaction furnace, micro capsuled powder, compression molding / injection molding under magnetic field, magnetic die and so on. Applied to DC brush seat motor for automotive use, the motor has become 50% small in size and weight. The commercialization of a half sized motor for automotive use has been realized up to the market share of 30%. At present, its commercialization is extending to various types of motors such as power tool, ABS motor, wiper motor, window motor, electric bike power motor, and compressor motor. It is expected that the applications will be increasingly enlarged to EV motor, wind generator, EPS motor, washing machine, and glass cutting machine. This innovative technology has realized Dy free high performance magnet and mudt make big contribution to not only rare element strategies but also energy conservation.

• Archives of Pharmacal Research
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• v.26 no.6
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• pp.504-510
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• 2003

The aim of this study is to prepare biodegradable microspheres without the use of surfactants or emulsifiers for a novel sustained delivery carriers of protein drugs. A poly($\varepsilon$-caprolactone)/poly(ethylene glycol)/poly($\varepsilon$-caprolactone) (CEC) triblock copolymer was synthesized by the ring-opening of $\varepsilon$-caprolactone with dihydroxy poly (ethylene glycol) to prepare surfactant-free microspheres. When dichloromethane (DCM) or ethyl formate (EF) was used as a solvent, the formation of microspheres did not occur. Although the microspheres could be formed prior to lyophilization under certain conditions, the morphology of microspheres was not maintained during the filtration and lyophilization process. Surfactant-free microspheres were only formed when ethyl acetate (EA) was used as the organic solvent and showed good spherical micro-spheres although the surfaces appeared irregular. The content of the protein in the micro-sphere was lower than expected, probably because of the presence of water channels and pores. The protein release kinetics showed a burst release until 2 days and after that sustained release pattern was showed. Therefore, these observations indicated that the formation of microsphere without the use of surfactant is feasible, and, this the improved process, the protein is readily incorporated in the microsphere.

• Proceedings of the Korean Society for Quality Management Conference
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• 2006.04a
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• pp.375-380
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• 2006

Recently European Council(EU) published the RoHS(restriction of the use of certain hazardous substances in electrical and electronic equipment) which is prohibit the use of Pb, Hg, Cd, $Cr^{+6}$, PBB or PBDE in the electrical and electronic equipments. So EU member States shall ensure that, from 1 July 2006, new electrical and electronic equipment put on the market does not contain 6 hazardous substances. So many kinds of projects is proceeding to ensure the reliability of Pb-free electronics in the worlds. Especially it is necessary to evaluate of Pb-free solder joints in electronics. Therefore, on this paper, we compared with solder joint strength of chip components, respectively SnPb, Pb-free solder as follows reliability test methods. We also measured the shear strength of solder joint and also compared the effects of environmental test methods. In this results, we analyzed and compared the shear strength variation as follows solder materials and reliability test conditions.

• Transactions of the Korean hydrogen and new energy society
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• v.25 no.6
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• pp.648-655
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• 2014

This paper describes the continuing effort to develope a single acting free-piston Stirling engine/alternator combination for use of the household cogeneration. Free piston Stirling engines(FPSE) use variations of working gas pressure to drive mechanically unconstrained reciprocating elements. Stirling cycle free-piston engines are driven by the Stirling thermodynamic cycle which is characterized by an externally heated device containing working gas that is continuously re-used in a regenerative, reversible cycle. The ideal cycle is described by two isothermal process connected by two constant volume processes. Heat removed during the constant volume cooling process is internally transferred to the constant volume heating process by mutual use of a thermal storage medium called the regenerator. Since the ideal cycle is reversible, the ideal efficiency is that of Carnot. Free-piston Stirling engine is have no crank and rotating parts to generate lateral forces and require lubrication. The FPSE is typically comprised of two oscillating pistons contained in a common cylinder. The temperature difference across the displacer maintains the oscillations, and the FPSE operate at natural frequency of the mass-spring system. The power is generated from a linear alternator. The purpose of this paper is to describe the design process of the single acting free-piston Stirling engine/alternator. Electrical output of the single acting free-piston Stirling engine/alternator is about 0.95 kW.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.17 no.2
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• pp.67-85
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• 2013

Reproducing Polynomial Particle Method (RPPM) is one of meshless methods that use meshes minimally or do not use meshes at all. In this paper, the RPPM is employed for free vibration analysis of shear-deformable plates of the first order shear deformation model (FSDT), called Reissner-Mindlin plate. For numerical implementation, we use flat-top partition of unity functions, introduced by Oh et al, and patchwise RPPM in which approximation functions have high order polynomial reproducing property and the Kronecker delta property. Also, we demonstrate that our method is highly effective than other existing results for various aspect ratios and boundary conditions.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2022.04a
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• pp.71-72
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• 2022

In the case of free-form buildings, it is difficult to reuse the form for panel production because the shape and size of the interior and exterior panels of the building are different. In general, it is a free-form concrete panel (FCP) production technology using the existing plywood formwork, and the form is produced in a different shape each time and is discarded after only one use. The production of these disposable forms requires enormous resources, including materials, labor and time. Hence, it is necessary to develop innovative forms that can be reused for sustainable FCP construction. In this study, a technology has been developed that combines 3D Plastering Technique (3DPT) to produce FCP. By applying this technology to free-form building projects, the time and cost required for FCP production can be reduced. However, specific studies on the production process for this technology have not been done yet. Therefore, the objective of this study is a basic study of free-form concrete panel production process using 3D plastering technique.