• Journal of Korean Neurosurgical Society
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• v.48 no.6
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• pp.534-537
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• 2010

Spinal extradural meningeal cyst has been rarely reported, whose etiologies are assumed to be the communication of cerebrospinal fluid (CSF) between intradural subarchnoid space and cyst due to the congenital defect in dura mater. Although the CSF communication due to this defect can be found, in most case, few cases in which there is a lack of the communication have also been reported. We report a case of the huge extradural meningeal cyst occurring in the thoracolumbar spine (from T10 to L2) where there was a lack of the communication between the intradural subarachnoid space and cyst in a 46-year-old man who presented with symptoms that were indicative of progressive paraparesis and leg pain. The patient underwent laminectomy and cyst excision. On intraoperative findings, the dura was intact and there was a lack of the communication with intradural subarachnoid space. Immediately after the surgery, weakness and leg pain disappeared shortly.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.7
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• pp.3247-3252
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• 2013

The convergence of ICT and cloud computing is treated as a main issue all over the fields including education. This development leads to change from e-learning to u-learning and smart education. Therefore, we need to study in term of the systematic and a long-term viewpoint how smart education environment have an influence on the practical space. And we need a concrete study for smart education space based on property of space. Under these critical mind, this study understands the smart education space in terms of the convergence of computing space and physical space. As a Result, smart education space have major property such as flexibility, communication, polyvalence.

• Journal of Astronomy and Space Sciences
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• v.37 no.4
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• pp.219-228
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• 2020

A CubeSat platform has become a popular choice due to inexpensive commercial off-the-shelf (COTS) components and low launch cost. However, it requires more power-efficient and higher-data rate downlink capability for space applications related to remote sensing. In addition, the platform is limited by the size, weight and power (SWaP) constraints as well as the regulatory issue of licensing the radio frequency (RF) spectrum. The requirements and limitations have put optical communications on promising alternatives to RF communications for a CubeSat platform, owing to the power efficiency and high data rate as well as the license free spectrum. In this study, we analyzed the performance of optical downlink communications compatible with CubeSat platforms in terms of data rate, bit error rate (BER) and outage probability. Mathematical models of BER and outage probability were derived based on not only the log-normal model of atmospheric turbulence but also a transmitter with a finite extinction ratio. Given the fixed slot width, the optimal guard time and modulation orders were chosen to achieve the target data rate. And the two performance metrics, BER and outage data rate, were analyzed and discussed with respect to beam divergence angle, scintillation index and zenith angle.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.14 no.1
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• pp.93-113
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• 2020

According to information theory, non-orthogonal transmission can achieve the multiple-user channel capacity with an onion-peeling like successive interference cancellation (SIC) based detection followed by a capacity approaching channel code. However, in multiple antenna system, due to the unideal characteristic of the SIC detector, the residual interference propagated to the next detection stage will significantly degrade the detection performance of spatial data layers. To overcome this problem, we proposed a modified power-domain non-orthogonal multiple access (P-NOMA) scheme joint designed with space-time coding for multiple input multiple output (MIMO) NOMA system. First, with proper power allocation for each user, inter-user signals can be separated from each other for NOMA detection. Second, a well-designed quasi-orthogonal space-time block code (QO-STBC) was employed to facilitate the SIC-based MIMO detection of spatial data layers within each user. Last, we proposed an optimization algorithm to assign channel coding rates to balance the bit error rate (BER) performance of those spatial data layers for each user. Link-level performance simulation results demonstrate that the proposed time-space-power domain joint transmission scheme performs better than the traditional P-NOMA scheme. Furthermore, the proposed algorithm is of low complexity and easy to implement.

• The Journal of the Korea institute of electronic communication sciences
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• v.12 no.6
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• pp.997-1002
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• 2017

Underwater communication, which is used acoustic channel of 1500[m/s] speed being different of wireless electric wave in terrestrial communication, is sensitive on water temperature and salinity and also affected from 3D underwater space. 3D underwater communication is sensitive on propagation loss of acoustic wave and underwater noise with complexity of communication space. In this paper, transmission performance with consideration of these characteristics of 3D underwater communication environments is measured and analyzed on MANET operated on 3D underwater communication environments. Some underwater MANET operation conditions will be suggested. Computer simulation with underwater simulator based on NS-2 will be used for performance measure, performance parameter like as throughput, transmission delay, packet loss rate and consumed energy will be used in simulation for performance measure.

• Journal of Astronomy and Space Sciences
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• v.27 no.1
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• pp.31-42
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• 2010

We developed a computer program to predict solar interference period. To calculate Sun's position, we used DE406 ephemerides and Earth ellipsoid model. The Sun's position error is smaller than 10arcsec. For the verification of the calculation, we used TU media ground station on Seongsu-dong, and MBSAT geostationary communication satellite. We analysis errors, due to satellite perturbation and antenna align. The time error due to antenna align has -35 to +16 seconds at $0.1^{\circ}$, and -27 to +41 seconds at $0.25^{\circ}$. The time errors derived by satellite perturbation has 30 to 60 seconds.

• Proceedings of the Korean Institute of Interior Design Conference
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• 2003.05a
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• pp.44-49
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• 2003

Exhibition can be a type of mass-communication since it should contains some 'meaning' or 'message' that is to be delivered. The purpose of visiting museum is to view exhibits. Thus, factors, such as exhibits, exhibition media, show-case, direction signs, and gates, form visual perception, which means there exists homogeneity between visual perception and action. Visitors acquire knowledge by the space interaction when one can acknowledge the consecutive time flow while moving along the exhibition space. Visitors' movements can be formed by visual and perceptive experience that follows environmental stimulus and individual desire. Therefore, museum visitors experience certain shift flow with visual perception caused by the continuity of space. Thus, the research on development of focus in continuity is required. In addition, if the quality of exhibition space and organized continuity with visual diversity can be improved in exhibition design, it would expand the function of communication in exhibitions.

• Proceeding of Spring/Autumn Annual Conference of KHA
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• 2009.04a
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• pp.95-100
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• 2009

In the coming 21st centuries, words of development of information communication technology among the key words being emerged as an important concern has been talked about frequently and ubiquitous environment that helps human living being networked with humans, objects and environments has been rapidly progressed, influencing significantly over the various fields as well as architectural area. And eventually in this architectural area, the space that is desired to be shown to and experienced by the people could be found in the creation of a space in a new form that has not been existed in this world by utilizing the information communication technology. The purpose of this study is to develop one-step advanced space from the existing space and to form a new paradigm of the future space by utilizing convergence technology and the psychology-based design principle of behavioral inducement called affordance.

• Journal of the Korean Graphic Arts Communication Society
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• v.19 no.2
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• pp.58-67
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• 2001

Gamut mapping is a technique that acts on cross-media color reproduction to transform a color between devices for the purpose of enhancing the appearance or preserving the appearance of an image. Gamut mapping essentially produces color conversion error which depends the gamut mapping method, source and destination devices, and sample points for gamut modeling. For color space conversion between monitor colors and printer colors, empirical representation using sample measurements is currently widely utilized. Color samples are uniformly selected in the device space such as CMY or RGB, represented as color patches, and then measured. However, in the case of printer, these color samples are not evenly distributed inside the printer gamut and the color conversion error is increased. Accordingly, this paper introduces a equally distributed color sampling method in CIELAB space, a device- independent color space, to reduce color conversion error, and the performance is analyzed via color space conversion experiments using tetrahedral interpolation.

• Journal of electromagnetic engineering and science
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• v.13 no.1
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• pp.16-21
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• 2013

This study presents the angular effects of virtual vertices inserted for effective treatment of the boundary edge laid on an infinite conducting surface in a half-space scattering problem. We investigated the angular effects of virtual vertices by first computing the radar cross section (RCS) of a specific scatterer; i.e., a tilted conducting plate in contact with the ground surface, by inserting the virtual vertex in half-space. Here, the electric field integral equation is used to solve this problem with various virtual vertex angles (${\theta}_{\nu}$) and conducting plate inclination angles (${\theta}_r$) ranging from $0^{\circ}$ to $180^{\circ}$. The effects of the angles ${\theta}_{\nu}$ and ${\theta}_r$ on the RCS computation are clearly shown with numerical results with and without the virtual vertices in free- and half-spaces.