• Journal of The Korean Astronomical Society
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• v.37 no.5
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• pp.571-574
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• 2004

Clusters of galaxies are filled with X-ray emitted hot gas with the temperature of T ${\~}$2-10 keV. Recent X-ray observations have been revealing unexpectedly that many cluster cores have complicated, peculiar X-ray structures, which imply dynamical motion of the hot gas. Moreover, X-ray spectra indicate that radiative cooling of the cool gas is suppressed by unknown heating mechanisms (the 'cooling flow problem'). Here we propose a novel mechanism reproducing both the inhomogeneous structures and dynamics of the hot gas in the cluster cores, based on state-of-the-art hydrodynamic simulations. We showed that acoustic-gravity waves, which are naturally expected during the process of hierarchical structure formation of the universe, surge in the X-ray hot gas, causing a serous impact on the core. This reminds us of tsunamis on the ocean surging into an distant island. We found that the waves create fully-developed, stable turbulence, which reproduces the complicated structures in the core. Moreover, if the wave amplitude is large enough, they can suppress the cooling of the core. The turbulence could be detected in near-future space X-ray missions such as ASTRO-E2.

• Culinary science and hospitality research
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• v.11 no.4 s.27
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• pp.102-117
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• 2005

It was maintained that successful establishment and accomplishment of outsourcing might be possible only when those eating-out companies re-establish their concept of management strategy, identify core competencies through value-chain analysis, make a through cost analysis, select cooperative companies via overall screening, expand the area of outsourcing, enhance partnership to improve service quality, harmonize bilateral organization culture, remove the ambiguity of contract terms, protect core competencies of the rest area, continue with evaluation and control, and spinoff or invest to a new specialized business. Then, it was suggested that highway rest area business construct the core competencies and introduce outsourcing from a future-oriented viewpoint so that they can concentrate the competencies to competitive area and expand outsourcing scope to professional area such as finance and accounting, general affairs, personnel affairs, logistics, marketing, and R&D. They need to make out the problem of productivity reduction resulted from many years working employee's old age, refine human resource, and maintain the standards of skill so that they can improve service quality of the rest area, streamline each organization currently having so a large manpower, reduce manpower, and improve the productivity.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1737-1740
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• 2005

As the various manufacturing technology of optical glass is developed, the aspherical lenses are applied to many fields. However, It is still very difficult to manufacture glass lens because of the high cost and the short life of core. In recent years, the demands of the aspherical glass lenses increase since it is difficult to obtain the desirable performance in the plastic lens. In the glass mold lens, it has merits of high productivity and reproductivity since lens is manufactured by the only forming with high precision mold. The fabricating conditions for glass mold lens are glass surface that does not cause fusion, viscosity of 108-1013 poise for the $0.2{\mu}m$ accuracy, and viscoelasticity for the roughness less than 100 angstrom. In this thesis, ultra-precision grinding characteristics of tungsten carbide for forming the aspherical glass lens core were studied and the result of it is applied to manufacture the tungsten carbide-base core of the glass lens used to the laser scanning unit and the camera phone.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1910-1913
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• 2005

As the various manufacturing technology of optical glass is developed, the aspherical lenses are applied to many fields. However, It is still very difficult to manufacture glass lens because of the high cost and the short life of core. In recent years, the demands of the aspherical glass lenses increase since it is difficult to obtain the desirable performance in the plastic lens. In the glass mold lens, it has merits of high productivity and reproductivity since lens is manufactured by the only forming with high precision mold. The fabricating conditions for glass mold lens are glass surface that does not cause fusion, viscosity of 108-1013 poise for the $0.2{\mu}m$ accuracy, and viscoelasticity for the roughness less than 100 angstrom. In this paper, ultra-precision grinding characteristics of tungsten carbide for forming the aspherical glass lens core were studied and the result of it is applied to manufacture the tungsten carbide-base cores of the glass lens used to the laser scanning unit and the camera phone.

• Proceedings of the Korean Society of Near Infrared Spectroscopy Conference
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• 2001.06a
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• pp.3101-3101
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• 2001

Near Infrared spectroscopy (NIR) used on human skin measurement was explored in the past decade. Many publications in different journals and magazines discussed the feasibility of the NIR technique for cosmetic product property studies. Based upon the results of pioneers, we have pursued some work of the NIR instrument coupled with a probe module for skin measurement in vivo and vitro. In part I of this paper, the specific Near Infrared spectroscopy instrument stability, human subject conditions and other parameters, which could affect the measurements reproducibility are discussed. Second derivative NIR spectra and Principle Components Analysis (PCA) are utilised for data interpretation. In part II of this paper, the relationship of human skin moisture and ageing, the gender information and finally, the discovery of penetration depth of NIR incident light on skin are reported. A theoretical penetration depth calculation equation is proposed. In part III, the study results of a couple of commercial skin care products effect will be described. The skin lotions were applied on human skin (in vivo) in order to exam the NIR feasibility to monitor the changes of moisture level. The results are consistently positive. From our primary study, it can conclude that the NIR is potentially a very powerful instrument for skin condition diagnostics, either for cosmetic and/or for medication purposes.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.3 s.234
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• pp.470-476
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• 2005

Ultra light metal structures have been studied for several years because of their superior specific stiffness, strength and potential of multi functions. Many studies have been focused on how to manufacture ultra light metal structures and optimize them. In this study, we introduced a new idea to make sandwich panels having octet truss cores. Wires bent in a shape of triangular wave were assembled to construct an Octet truss core and it was bonded with two face sheets to be a sandwich panel. The bending & compressive strength and stiffness were estimated through elementary mechanics for the sandwich specimens with two kinds of face sheets and the results were compared with the ones measured by experiments. Some aspects of assembling and mechanical behavior were discussed compared with Kagome core fabricated from wire, which had been introduced in the authors' previous work.

• The Journal of Society for e-Business Studies
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• v.23 no.1
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• pp.37-45
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• 2018

The current system upon which a variety of programs are in operation has continuously expanded its domain from conventional single-core and multi-core system to many-core and heterogeneous system. However, existing researches have focused mostly on parallelizing programs based CUDA framework and rarely on AMD based GCN-GPU optimization. In light of the aforementioned problems, our study focuses on the optimization techniques of the GCN architecture in a GPGPU environment and achieves a performance improvement. Specifically, by using performance techniques we propose, we have reduced more then 30% of the computation time of matrix multiplication and convolution algorithm in GPGPU. Also, we increase the kernel throughput by more then 40%.

• Journal of Advanced Marine Engineering and Technology
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• v.30 no.5
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• pp.636-644
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• 2006

Recently, there were some successful examples that the laser welding was introduced into production line. However, the spread of laser welding is not sufficient in many industries. There are several reasons why it is difficult to penetrate the laser welding into production lines. Because it is different from reflection, absorption and permeation of laser beam according to material and surface condition. Moreover, there are significant problems in processing such as absorption and scattering of beam by the induced plasma or plume. Therefore, understanding of mechanism on formation of weld defect in laser welding of the laminated core for motor is very important. In this paper, it was analyzed in terms of materials which was source of defect in laser welding and conventional arc welding. As a results of analysis, insulation coating film of the laminated core was judged to main factor of weld defect. it could be well aware as tracing carbon volume, and it was deduced that weld defect by insulation coating film was caused by difference of mechanism between the two heat sources.

• Review of Korean Society for Internet Information
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• v.14 no.3
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• pp.5-20
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• 2013

ICANN has been governing the Domain Name System(DNS) "technically" since 1998. The architecture is called Internet Governance, and it brings about many different discourses; "What does that govern?", "Who delegate its role to ICANN?"," How could the regime ensure fairness?" etc. This article will analyze on Internet Governance by applying the government approach of Foucault, and try to compare two parts, the 'core' and the 'edge' of Internet Governance for method. Whereas the 'core' of it refers the site that be governed by the formal contract directly, the 'edge' as the rest of it means informal friendly relations with ICANN. The 'core' rule was stemmed from technological community such as IAB or IETF historically. They had invented new world and its population to integrate the technical order as protocol and the semiotic order as language, that be based on new government mode. On the other hand, ".KR" domain, one of the 'edges', has been evolved into more heterogeneous system, through contest and conflict between traditional state and Internet Governance. The governed object of ".KR" domain is situated in the crossing of each other the 'protocol user', the 'language-semiotic user' and the' geographical resident'. Here the 'geographical resident' rule was weird for DNS, so that shows the internal lack of Internet Governance. It needs to move to the concept of 'Hangeul(Korean-language) user' rather than the 'geographical resident'.

• Journal of Digital Convergence
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• v.7 no.3
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• pp.35-47
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• 2009

The IS project is getting more and more complicated and large-scaled. Many researchers and practitioners are interested in the IS development methodologies, automated tools and techniques, TQM to decrease project failure, and to increase IS performance. But, in spite of such various efforts, the latest Standish Group's research indicates that the project scale is bulkier than $1{\sim}2$ year ago and IS development project's batting average falls from 34% to 28% at the same time, proceeded project is increased, and project discharged arrives to $15%{\sim}18%$. According to a research, success possibility increased by 37% after a year of PMO introduction, and increased sharply by 62% after 2 years and by 65% after S years. This research has a goal to survey how the PMO function and operation type affect the IS project performance in the financial industry. I determine nine independent variables and three dependent variables from previous researches. The results of this study are that the four core functions of PMO have relationship with project performance. But, technical support function does not relate with organization performance. Among the four core PMO operation types, three types have an effect on the IS project performance except the perfectionist type.