• 한국전자통신학회논문지
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• 제11권12호
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• pp.1159-1164
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• 2016

본 연구는 디지털위성중계기용 SHF 대역 저잡음증폭장치의 설계 및 구현에 대해 기술하였다. 잡음지수 최소화를 위하여 저잡음 증폭소자인 HEMT(: High Electron Mobility Transistor)소자를 적용하였고, 우주환경에 대한 사전 시뮬레이션 분석을 통하여 장비 오동작 가능성을 최소화 시켰다. 발사환경 시 발생하는 진동 및 우주방사능에 의한 TID(: Total Ionizing Dose)에 대한 시뮬레이션을 통해 신뢰성 있는 저잡음증폭장치를 설계하였으며, 제작 후 주요 성능지표에 대해 만족여부 확인 및 사전 성능 시뮬레이션 결과와 비교하였다.

• IEIE Transactions on Smart Processing and Computing
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• 제3권1호
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• pp.10-18
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• 2014

From the perspective of reducing the sampling cost of color images at high resolution, block-based compressive sensing (CS) has attracted considerable attention as a promising alternative to conventional Nyquist/Shannon sampling. On the other hand, for storing/transmitting applications, CS requires a very efficient way of representing the measurement data in terms of data volume. This paper addresses this problem by developing a measurement-coding method with the proposed customized Huffman coding. In addition, by noting the difference in visual importance between the luma and chroma channels, this paper proposes measurement coding in YCbCr space rather than in conventional RGB color space for better rate allocation. Furthermore, as the proper use of the image property in pursuing smoothness improves the CS recovery, this paper proposes the integration of a low pass filter to the CS recovery of color images, which is the block-based ${\ell}_{20}$-norm minimization. The proposed coding scheme shows considerable gain compared to conventional measurement coding.

• Journal of Korean Neurosurgical Society
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• 제48권6호
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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.

• 한국산학기술학회논문지
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• 제14권7호
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• pp.3247-3252
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• 2013

정보기술의 융합화와 클라우드 컴퓨팅의 확산 등 빠르게 발전하는 정보통신기술은 학제간 융복합을 통해 새로운 교육의 패러다임 시대를 열고 있다. 정보통신기술의 발전에 따라 그동안 교육환경은 이러닝에서 유러닝을 거쳐 이제 스마트교육으로 변화되고 있다. 이미 교육계에서는 향후 교육환경의 변화를 가져올 스마트교육에 대한 다양한 연구들이 진행되고 있지만 스마트 환경이 구축될 교실공간, 곧 물리적 공간환경에 대한 연구는 거의 이루어지지 않고 있다. 이러한 문제의식 하에 본 연구는 교육의 새로운 패러다임으로 등장한 스마트교육과 스마트교육이 적용되는 물리공간의 특성을 살펴보았다. 그 결과 스마트교육이 적용될 물리공간은 공간의 소통성, 경계의 유연성, 요소의 다가성이 그 특성으로 나타남을 알 수 있었다.

• Journal of Astronomy and Space Sciences
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• 제37권4호
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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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• 제14권1호
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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.

• 한국전자통신학회논문지
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• 제12권6호
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• pp.997-1002
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• 2017

무선전파를 사용하는 지상통신과는 달리 1500[m/s] 속도의 음향채널이 사용되는 수중통신은 수중온도, 염도를 비롯한 통신환경에 민감할 뿐 아니라 3D 공간의 영향을 받는다. 3D 수중통신은 통신공간의 복잡성과 더불어 음파의 전파손실, 해저환경에서 발생되는 음향잡음 등에 민감하다. 본 연구에서는 이와 같은 3D 수중통신환경의 특성을 고려하여 3D 수중통신환경에서 운용되는 MANET을 대상으로 전송성능을 측정 분석하고 이를 토대로 수중 MANET 운용조건을 제시한다. 본 연구는 NS-2를 기반으로 구축한 수중통신 시뮬레이터를 사용하여 수행하며, 성능파라미터로는 처리율, 전송지연, 패킷손실율 및 소비에너지를 사용한다.

• Journal of Astronomy and Space Sciences
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• 제27권1호
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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.

• 한국실내디자인학회:학술대회논문집
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• 한국실내디자인학회 2003년도 춘계학술발표대회 논문집
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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.

• 한국주거학회:학술대회논문집
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• 한국주거학회 2009년 춘계학술발표대회 논문집
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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.