• Journal of KSNVE
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• v.3 no.1
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• pp.77-82
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• 1993

In general, the dynamic analysis with FEM(Finite Element Method) of large structures requires large computer memory space and long computational time. For the purpose of economical dynamic analysis of large structures, most of engineers want to use an efficient solution algorithm. This paper reports the modified CMS(Component Mode Synthesis) method which uses more efficient algorithm than the classical CMS method. In this paper, it is shown that Ritz vector sets can play the role of normal mode vector sets of substurctures in the CMS algorithm. The modified CMS method has good convergence performance compared with that of the classical CMS method.

• Journal of Korean Neurosurgical Society
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• v.37 no.1
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• pp.70-72
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• 2005

Primary spinal cord lymphomas are rare, and are either extra-/intradural masses with leptomeningeal infiltration or intramedullary in nature. The authors present a patient with a diffuse large B-cell lymphoma involving the sacral nerve root, extension to extradural space, and the cranial nerve.

• Journal of the Korean housing association
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• v.19 no.4
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• pp.41-48
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• 2008

In this study, an analysis is carried out on the acoustic design for an indoor gymnasium scheduled to be built at Buan County, Chonbuk Province. By way of background, the study examines the case of a large-scale indoor gymnasium that has been constructed in the local area of Hangan-myeon. There are many examples whereby this gymnasium could be used not only as a sporting facility for the residents, but also as a multipurpose space for public performances such as leisure activities, lectures, assembling activities, theatre and concerts etc. In order to maximize the functional utilization of such an indoor gymnasium, it is important to simultaneously verify the acoustic capabilities of the space in terms of Definition of both Voice and Music. However, as a large-scaled athletic facility, the building was designed with a high ceiling-height to accommodate its functional characteristics. The space forms a Sound Focus whereby the sound is concentrated at a specific part, and because the vibration of sound is too loud due to its broad volume, acoustic defects arise such as a significant number of Echoes. Using this gymnasium as a precedent, this study proposes an acoustic design based on the drawings of the indoor gymnasium that is scheduled to be built at B County, Chonbuk Province. The gymnasium is equipped with an optimized acoustic condition passing through the Acoustic Simulation Phase. From the results of an Acoustic Simulation, we can design an indoor gymnasium that is equipped with a considerably satisfying and improved acoustic performance compared with the building before it was reformed. It is also considered that the use of such materials can fundamentally reduce construction costs and can improve acoustic performance, at the planning and design stages for similar sporting facilities in the future.

• Journal of The Korean Astronomical Society
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• v.46 no.1
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• pp.33-40
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• 2013

We investigate the dependence of the extended X-ray emission from the halos of optically luminous early-type galaxies on the small-scale (the nearest neighbor distance) and large-scale (the average density inside the 20 nearest galaxies) environments. We cross-match the 3rd Data Release of the Second XMMNewton Serendipitous Source Catalog (2XMMi-DR3) to a volume-limited sample of the Sloan Digital Sky Survey (SDSS) Data Release 7 with $M_r$ < -19.5 and 0.020 < z < 0.085, and find 20 early-type galaxies that have extended X-ray detections. The X-ray luminosity of the galaxies is found to have a tighter correlation with the optical and near infrared luminosities when the galaxy is situated in the low large-scale density region than in the high large-scale density region. Furthermore, the X-ray to optical (r-band) luminosity ratio, $L_X/L_r$, shows a clear correlation with the distance to the nearest neighbor and with large-scale density environment only where the galaxies in pair interact hydrodynamically with seperations of $r_p$ < $r_{vir}$. These findings indicate that the galaxies in the high local density region have other mechanisms that are responsible for their halo X-ray luminosities than the current presence of a close encounter, or alternatively, in the high local density region the cooling time of the heated gas halo is longer than the typical time between the subsequent encounters.

• Aerospace Engineering and Technology
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• v.6 no.1
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• pp.64-73
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• 2007

A Large thermal vacuum chamber (LTVC) for space environment simulation on large satellites was successfully developed and constructed by KARI (Korea Aerospace Research Institute) in Korea with a local company. This chamber has an effective diameter of 8 meters and depth of 10 meters, and is composed of vacuum system, thermal control system, and anti-vibration system. Temperature below $-190^{\circ}C$ is maintained over the thermal shroud wrapping a satellite under $3.7{\times}10^{-5}Pa$ ($5{\times}10^{-7}torr$) vacuum level, and optical test can be done in this chamber by seismic mass with $10^{-5}g_{rms}$ or lower vibration level. In addition, the shroud temperature can be increased up to $123^{\circ}C$ using halogen lamps. Chamber control program based on PLC (Programmable Logic Controller) could control this large thermal vacuum chamber automatically.

• Journal of the Korean Mathematical Society
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• v.31 no.2
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• pp.279-288
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• 1994

• The Bulletin of The Korean Astronomical Society
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• v.14
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• pp.13.2-13.2
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• 1989

• Journal of Korean Association for Spatial Structures
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• v.6 no.1 s.19
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• pp.7-14
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• 2006

• Journal of Korean Association for Spatial Structures
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• v.18 no.1
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• pp.6-17
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• 2018

• Kyungpook Mathematical Journal
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• v.28 no.1
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• pp.107-114
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• 1988