• Proceedings of KOSOMES biannual meeting
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• 2017.04a
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• pp.193-193
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• 2017

• International Journal of Aerospace System Engineering
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• v.2 no.1
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• pp.24-30
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• 2015

In helicopter bearingless rotor design, the flexbeam is the key component of rotor system, which plays an importantrole in the blade flapping, lead-lag movement, torsion, and load transfer. Flexbeam must have the minimum torsion stiffness with enough tension strength. In this paper, we first investigated the torsion stiffness of different cross section configurations of the flexbeam through some simple experiments. Then we analyzed a rotor's dynamical characteristics with finite element method and got the rotor's fan plot. After that, we studied the relationship between the frequency changes with the spanwise distribution of mass and stiffness in bearingless rotor. Finally, we analyzed the influence of the flexbeam on dynamical characteristics of the bearingless rotor system, and completed the design of this type of rotor flexbeam.

• Journal of Environmental Science International
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• v.17 no.12
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• pp.1373-1380
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• 2008

Anthracene appended new host compounds have been synthesized by imine reaction. Fluorescent open chain host compounds Trisanthryl-tris(2-aminoethyl)imine 1 was synthesized from the reaction of tris(2-aminoethyl)amine and anthracene-9-carboxaldehyde in EtOH. Tris-10-chloroanthryl-tris(2-aminoethyl)imine 2 was synthesized from tris(2-aminoethyl)amine and 10-chloro-9-anthraldehyde in EtOH. The structures of all reaction product were identified by $^1H$ NMR, $^{13}C$ NMR, GC/MS, FAB Mass, IR spectrum and DSC. Cation complexation behavior was investigated by fluorescence spectroscopy measurements. The capability of transition metals cation recognition between fluorescent open chain host compound 1, 2 were investigated with $Co^{2+},\;Ni^{2+}\;and\;Cu^{2+}$. The fluorescence intensity was increased by host compounds corresponding guest cations. The relative order of fluorescence intensity changes were $Co^{2+}>Cu^{2+}>Ni^{2+}$. Compound 2 is very sensitive fluorescent sensor of $Co^{2+}$ ion.

• Journal of Korean Foot and Ankle Society
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• v.16 no.3
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• pp.141-147
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• 2012

A tarsal coalition is an abnormal union between 2 or more tarsal bones of the hind- and midfoot, which can be congenital or acquired. The documented overall incidence of tarsal coalition is 1% or less. The resulting abnormal articulation leads to accelerated degeneration within adjacent joint. Pain is often diffuse, exacerbated by strenuous activity or following an ankle sprain. The findings on physical examination is protruded mass, diminished range of motion of the involved joint. It is possible to identify of tarsal coalitions with conventional radiography, but CT scanning necessary to evaluate of the size, location, characteristic and preoperative planning of tarsal coalitions. The initial treatment for a tarsal coalition is conservative, but tarsal coalitions unresponsive to conservative treatment, are managed by coalition resection, or arthrodesis in case of presence of degenerative changes.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.4 s.235
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• pp.477-484
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• 2005

Model fer the dynamic simulation of dynamic behaviors of a solid oxide fuel cell (SOFC) is provided. This model is based upon (1) coupled mass and heat transfer characteristics and (2) important chemical reactions such as electrochemical and reforming reactions in high temperature fuel cells such as SOFC. It is found that the thermal inertia of solid materials in SOFC plays an important role to the dynamic behavior of cell temperature. Dynamic characteristics of cell voltage, power, and chemical compositions with different levels of load change are investigated.

• Journal of the Korean Society for Library and Information Science
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• v.16
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• pp.243-279
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• 1989

Public library effectiveness is determined by a complexity of the internal and external environments of the library. The purpose of this article is to investigate community environments and library resources as determinants of the output measures of the 15 municipal libraries in Seoul and to cope with changes in the environments for the improvement of their performance. This study is based on the hypotheses that the library's output would be proportioned to the size of budget and library collection, and to the relationships between the characteristics of the library and of the community in which the library develops. The variables identified in this .study are population density, family size, institutions (social, cultural, financial and educational), presence of the mass media, size of service area, and economic level of the community. The output measures employed for analysis are: number of professional staff, expenditures, number of books in the collection, number of books added annually, total circulation, number of library visits, circullation per capita, library visits per capita, .and registration as a percentage of population. The recommendation made in this study is the innovation of the 15 libraries in organization.

• Journal of Korean Neurosurgical Society
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• v.30 no.7
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• pp.921-924
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• 2001

The authors report a case of cholesterol granuloma in the sphoid sinus in 54-year old woman, which is probably the first report of cholesterol granuloma arising primarily in the sphenoid sinus apart from the petrous bone. The initial clinical presentations were unilateral decreased visual acuity and facial sensory change. The mass was removed totally via transsphenoidal route and the pathological examination revealed cholesterol clefts and chronic granulomatous changes. The differences between the present case and the previous reports are discussed.

• Journal of Welding and Joining
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• v.34 no.4
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• pp.9-16
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• 2016

Metal parts are produced by conventional methods such as casting, forging and cutting, extrusion, etc. However, nowadays, with additive manufacturing (AM), it is possible to directly commercialize by means of stacking of equipment to the 3D drawing and use of high precision tools such as laser source. Thus, drawing of materials is an important aspect in delivering good products. AM deals with production of lighter aircraft parts and few more three-dimensional molds, it wish to manufacture special medical parts and want to steadily expand the new market area. The cost of related equipment and materials are still expensive and difficult to obtain on a mass production. However, the ability to make changes and lead the innovation in the paradigm of traditional manufacturing process is still effective. In this paper, we introduce metal AM and the principles of the related devices, metal powder production process, and their application.

• Bulletin of the Korean Chemical Society
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• v.16 no.5
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• pp.443-449
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• 1995

N-(Isopropyloxycarbonyloxy)maleimide (iPOCMI) has been synthesized and polymerized to give both the homopolymer and copolymers with substituted styrenes. These polymers were readily deprotected by thermolysis of the isopropyloxycarbonyl (iPOC) groups to provide the corresponding N-hydroxymaleimide (HOMI) polymers. The homopolymer and styrenic copolymers of iPOCMI were radically obtained in higher conversion and higher molecular weight than those obtained by direct polymerizations of N-hydroxymaleimide. The homopolymer of iPOCMI was transformed into poly(N-hydroxymaleimide)P(HOMI) by thermolysis of iPOC groups at 205 $^{\circ}C$ with concurrent release of propene and carbon dioxide. The copolymer of iPOCMI and styrene was thermally deprotected to the copolymer of HOMI and styrene at 235 $^{\circ}C.$ The mass loss was 28% and the Tg of the resulting copolymer was 250 $^{\circ}C.$ The thermal deprotection readily provided the desired, polar HOMI polymers which have Tgs above 240 $^{\circ}C.$ The deprotection was accompanied by large changes in aqueous base solubility.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.239-243
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• 2012

This paper is concerned with turbulent flow computations using Large Eddy Simulation (LES) and the flow interaction of vortex shedding in a cylindrical duct flow driven by mass blowing through the wall. The purpose is to analyze non-linear combustion characteristics in the presence of vortex shedding generated in a hybrid rocket motor. Experimental studies have shown sudden changes in pressure (referred as a DC-shift), which depend on the strength of vortex strength of incoming flow. The combustion instability because of a sudden change in pressure fluctuations is mainly related with the interaction between vortex shedding. Therefore LES computation on a duct with injected normal blowing was performed to simulate the turbulent flow interactions with the behaviors of vortices and vortex structures along the injected wall.