• The Journal of the Acoustical Society of Korea
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• v.15 no.4E
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• pp.9-13
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• 1996

We developed an iterative algorithm which could improve the resolution of reconstructed tomograms having random attenuation patterns and analyzed the limitation of this algorithm. The simple back-and forth propagation algorithm has depth resolution about four wavelengths. An iterative algorithm, based on back-and-forth propagation, can be used to improve the resolution of reconstructed tomograms. We analyzed the wavefield for multi-layered specimen and programmed iterative algorithm using Clanguage. Simulation results show that the images get clearer as the number of iterations increases. Also, unambiguous images can be reconstructed using this algorithm even when the layer separation is only two wavelengths. However, this iteration algorithm comes up with an incorrect solution for the number of projections less than five.

• Korean Journal of Computational Design and Engineering
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• v.2 no.3
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• pp.142-149
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• 1997

This study is intended to develop a Feature based modeler. It is difficult to integrate CAD and CAM/CAPP with information that is given only by a conventional CAD system. Therefore a lot of studies have concentrated on a Feature based CAD system. But conventional Feature based modelers have had limitation on providing sufficient information related to Feature interaction. If a Feature based modeler is to be used in assembly simulation, a new Feature-based modeling method needs to be developed. Also to support collision detection between parts, we have to handle Feature interaction systematically. Therefore we suggest Cell data structure which handles interaction of Features by volume. The volume created by Feature interaction is saved as a Cell. With the Cell structure we solve problems involved with Feature interaction. This study shows how the Cell data structure can manage Feature interaction and give enough information in assembly simulation.

• Korean Journal of Computational Design and Engineering
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• v.17 no.5
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• pp.342-352
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• 2012

As a futuristic construction model, building information model (BIM) based project management system (PMIS) and mobile BIM simulator apps have been showing visible sign. However, researches on the BIM based 3D simulator using mobile device are hard to find result from limitation of mobile device (slow speed at huge 3D file, display size, and etc.) and undefined standard of business processes. Therefore, this research aims at studying application of mobile BIM apps based on cloud computing. Total 8 BIM cloud apps were selected and analyzed in the 5 application feasibility characteristics (speed, view, inquiry, markup, and usability). This research would be essential phase to construct BIM based mobile project management system using cloud computing in the future.

• Journal of the Korean Chemical Society
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• v.12 no.1
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• pp.35-38
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• 1968

Radio iodination of various aromatic derivatives (aniline, toluene, iodobenzene, acetanilide, benzene, benzoic acid) were achieved at low temperature by a chloroamine-T procedures in presence of polar solvent(dioxane). Organic base (piperidine) was used as the catalyst. Iodine replacement reaction had occured on the aromatic or alicyclic ring by this reaction, and the kind and ratio of iodinated products were proved to be different from those of usual iodide reaction in organic solvent at low temperature. The reactivity of various aromatic or alicyclic compounds towards the present iodination system was evaluated and the scope and limitation of the present procedures in the preparation of radio pharmaceuticals were discussed.

• Journal of the Korean Chemical Society
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• v.3 no.1
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• pp.3-8
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• 1954

Fowler obtained thermodynamic quantities assuming the theory which could be derived by representing the system with microcanonical ensemble, in order to introduce the temperature T of the system proper, he considered the combined systems which are composed of the system proper and another arbitrary system that is in thermal contact with the former, and represented the combined system by a microcanonical ensemble, here, he used the steepest descent method in his calculation. This Fowler's treatment is not only unsatisfactory at the point of theoretical view but also he could not make the formulation of free energy of Helmholtz's so that this formular was forced to be assumed. From the point of Quantum Statistical Mechanical view, the materially closed system which is in an equilibrium state with the temperature T is best represented by canonical ensemble. At the actual derivation of the distribution law and thermodynamic quantities, however, in order to avoid the difficulty of calculation Tolman proceeded his calculation either representing the system proper by the grand-canonical ensemble or adding a certain limitation.

• International Journal of Internet, Broadcasting and Communication
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• v.7 no.2
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• pp.117-122
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• 2015

Our research team proposed a flux-offset type fault current limiter as a new limiter. The flux-offset type fault current limiter uses a fault current limit technology based on the flux offset principle of the primary and secondary windings of a transformer. Stable fault current limit characteristics were achieved through a preliminary study. However, it was discovered that the initial fault current was not limited. Therefore, in this paper, a high-speed interrupter and a superconducting element were separately applied to the secondary winding of the flux-offset type fault current limiter and the operating characteristics were comparatively analyzed. In the experiment, when the superconducting element was applied to the secondary winding of the transformer, the initial fault current was limited while the limitation in the operation time was further shortened.

• International Commerce and Information Review
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• v.6 no.3
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• pp.137-157
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• 2004

It is very necessary to find how to develop international government procurement by analyzing functions and roles of information providing circumstance and existing total international government procurement information system. In addition, it would require to draw up a way of improving current international government procurement information system based on the problems of existing system. In this study, we analyze the current status of Korean international government procurement information system and give an idea of mutual cooperating with DGMARKET, a good example of international government procurement information system. As a practical method, cooperating with DGMARKET by building each countries' gateway will be very helpful in cost saving and providing information. It will also complement the limitation of Korean system's one way service. But supplying only international government procurement information is insufficient in realization of e-trade in international goverment procurement market. To settle these problems, treating international government procurement as a same field of trade and giving political support and incentive to company which hopes to participate international goverment procurement are absolutely needed.

• International Commerce and Information Review
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• v.6 no.3
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• pp.81-99
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• 2004

Research relevant to the electronic commerce tends to either overestimate or underrate the role of Information and Communication Technology (lCT). There is both technological skepticism within the social science circles and technical optimism within the engineering and computing field. Each perspective seems to have a limitation in adequately explaining the phenomenon of electronic commerce diffusion. Therefore, this research attempts to explore major characteristics of Web-based shopping systems as enablers of new business, concerning both the technical and business aspects in contemporary electronic commerce settings. On this basis, this paper addresses a configuration model of WBSS on the harmonious perspective concerning both the technical and business issues. It is our hope that both technical perspective and business perspective for exploring WBSS's configuration model presented in this paper can be an initial step towards a more balanced debate of ICT role, for electronic commerce.

• Journal of the Korea Society of Computer and Information
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• v.21 no.3
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• pp.123-128
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• 2016

This study aims to analyze the causal relation between identity and school adaptation of multicultural family children, starting from necessity of empirical research considering insufficient preceding research. To achieve the purpose of the research, this study implemented empirical analysis regarding the causal relation between factors of self-identity and school adaptation. As a result, factors of self-identity implies significant effect on school regulations, while factors of school adaptation partially have an effect on school class and relations with a teacher and friend. Based on the result of verification, this study emphasizes teachers' effort as well as comprehensive and practical development of an educational program to help children from multicultural family establish the right self-identity for settling into school life. Moreover, the limitation of this study and future research direction is presented.

• Proceedings of the Korean Society of Computer Information Conference
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• 2013.07a
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• pp.105-108
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• 2013

The commercialization of UCC was already initiated, and there are some successful cases like 'YouTube.' However, the development level of UCC is not mature, stable yet. It's because most of the UCC users are young people and the contents are mainly about humor, funny, minor story. In other words, the practical use of UCC is not totally popularized but partly active. Therefore we want to think out 'how UCC can be utilized by many people and applicable to many industries.' UCC has enough possibility to be advanced, and it will greatly influence the society. In this paper, we will first explain Web 2.0 and the present conditions of online movies. After analyzing the problems and limitation of today, we will propose some suggestions for plans for practical utilization of UCC.