• 한국통신학회논문지
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• 제22권1호
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• pp.193-204
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• 1997

In this research we propose the design of the Order Statistic-Adaptive Weighted Average Hybrid(OS-AWAH) filter which can suppress noise from the corrupted image sequence effectively while preserving the image structure. The proposed filter combines the desirable properties of the order static based spatial filter which can preserve the image structure while reducing noise and the adaptive weighted average based temporal filter which can adapt the filtering weights according to the amount of motion without motion estimation. Performance characteristics of the OS-AWAH filter in noisy sequences containing moving step edges are investigated throuth computer simulations and compared with the median based filters such as 3-D WM(weighted median) filter, MMF (multistage median filter), ADCWM(adaptive directional center weighted median) filter. The visual evaluations are also carried out by applyin gthe filters to the real images. The statistical analysis and experimental reslts show that the OS-AWAH filter is effective in preserving image structures while suppressing noise effectively without motion compensation preprocessing.

• ETRI Journal
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• 제38권1호
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• pp.81-89
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• 2016

In this paper, a beam ID preamble (BIDP) technique, where a beam ID is transmitted in the physical layer, is proposed for efficient beam training in millimeter-wave cellular communication systems. To facilitate beam ID detection in a multicell environment with multiple beams, a BIDP is designed such that a beam ID is mapped onto a Zadoff-Chu sequence in association with its cell ID. By analyzing the correlation property of the BIDP, it is shown that multiple beams can be transmitted simultaneously with the proposed technique with minimal interbeam interference in a multicell environment, where beams have different time delays due to propagation delay or multipath channel delay. Through simulation with a spatial channel model, it is shown that the best beam pairs can be found with a significantly reduced processing time of beam training in the proposed technique.

• 천문학회지
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• 제52권5호
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• pp.145-158
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• 2019

We conducted a survey of open clusters within 1 kpc from the Sun using the astrometric and photometric data of the Gaia Data Release 2. We found 655 cluster candidates by visual inspection of the stellar distributions in proper motion space and spatial distributions in l - b space. All of the 655 cluster candidates have a well defined main-sequence except for two candidates if we consider that the main sequence of very young clusters is somewhat broad due to differential extinction. Cross-matching of our 653 open clusters with known open clusters in various catalogs resulted in 207 new open clusters. We present the physical properties of the newly discovered open clusters. The majority of the newly discovered open clusters are of young to intermediate age and have less than ~50 member stars.

• Journal of Communications and Networks
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• 제1권3호
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• pp.182-188
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• 1999

The optimal joint maximum-likelihood sequence estima-for using an array of antennas is derived for synchronous direct sequence-code division multiple access (DS-CDMA) system. Each user employs a rate 1/n convolutional code for channel coding for the additive white Gaussian noise (AWGN) channel. The array re-ceiver structure is composed of beamformers in the users' direc-tions followed by a bank of matched filters. The decoder is imple-mented using a Viterbi algorithm whose states depend on the num-ber of users and the constraint length of the convolutional code. The asymptotic array multiuser coding gain(AAMCG)is defined to encompass the asymptotic multiuser coding gain and the spatial information on users' locations in the system. We derive the upper and lower bounds of the AAMCG. As an example, the upper and lower bounds of AAMCG are obtained for the two user case where each user employes the maximum free distance convolutional code with rate 1/2. The enar-far resistance property is also investigated considering the number of antenna elements and user separations in the space.

• Molecules and Cells
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• 제26권5호
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• pp.474-480
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• 2008

OsMADS1 is a rice MADS box gene necessary for floral development. To identify the key cis-regulatory regions for its expression, we utilized transgenic rice plants expressing GUS fusion constructs. Histochemical analysis revealed that the 5.7-kb OsMADS1 intragenic sequences, encompassing exon 1, intron 1, and a part of exon 2, together with the 1.9-kb 5' upstream promoter region, are required for the GUS expression pattern that coincides with flower-preferential expression of OsMADS1. In contrast, the 5' upstream promoter sequence lacking this intragenic region caused ectopic expression of the reporter gene in both vegetative and reproductive tissues. Notably, incorporation of the intragenic region into the CaMV35S promoter directed the GUS expression pattern similar to that of the endogenous spatial expression of OsMADS1 in flowers. In addition, our transient gene expression assay revealed that the large first intron following the CaMV35S minimal promoter enhances flower-preferential expression of GUS. These results suggest that the OsMADS1 intragenic sequence, largely intron 1, contains a key regulatory region(s) essential for expression.

• 대한기계학회논문집A
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• 제20권2호
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• pp.431-439
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• 1996

본 연구에서 탐구된 새로운 설계조건과 설계원칙들을 적용함으로써 세탁기용 트랜스미션으로 대표되는 기계 시스템을 효과적으로 설계할 수 있었다. 개발된 자동설계 프로그램을 이용함으로써 다양한 설계시뮬레이션을 단기간에 수행할 수 있었으며 설계 실무자로 하여금 설계변수와 상태변수 등에 관한 민감도를 파악하게 하는데 매우 효과적이었다. 본 연구에서 새롭게 제안된 시스템 설계조건들과 설계원치기들은 세탁기용 트랜스미션 뿐만 아닌 일반적인 기계시스템 설계시에도 적용될 수 있는 것으로 판단된다.

• 한국정보통신학회논문지
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• 제9권5호
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• pp.1019-1024
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• 2005

MPEG-2로 부호화 된 영상에서 발생하는 전송 오류는 화질의 열화를 가져오고, 시공간적으로 오류를 전파시킨다. 특히 비디오 비트열에서 헤더 정보의 오류는 복호화 과정 전체에 영향을 미치므로 데이터 정보의 오류와 달리 전체 영상에 심각한 화질의 열화를 일으킬 수 있다. 따라서 헤더 정보에서의 오류를 복원하는 것은 데이터 정보에서 오류를 복원하는 것보다 더 중요하다. 본 논문에서는 LSB(least significant bit) 부호화를 이용하여 헤더 정보를 양자화 된 DCT(discrete cosine transform) 계수에 반복적으로 삽입하여 전송함으로써 MPEG-2의 신택스 구조 그대로 유지하면서 헤더 정보의 오류를 복원할 수 있는 방법을 제안한다.

• 대한공간정보학회지
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• 제18권2호
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• pp.93-97
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• 2010

본 연구에서는 카메라 자세 정보가 없는 무인헬기에 탑재된 카메라로부터 취득된 연속영상을 등록하기 위한 개량형 KLT기법을 제시하였으며 그 절차는 다음과 같이 구성된다. 초기 특징점은 연속영상에서 모서리점을 검출하고 동적프로그래밍에 의한 특성곡선매칭에 의해 특징점을 추적하였다. 추적된 특징점 중 오류점은 RANSAC추정법에 의해 제거되며 호모그래피이론에 의해 나머지점은 정확한 정합점으로 분류되었다. 영상등록에 의한 편위보정영상모자이크생성은 쌍일차보간법에 의해 생성하였으며, 결과분석을 통해 제시된 방법이 흔들림이 있는 연속영상을 등록하는데 적합한 방법임을 제시하였다.

• 대한전자공학회논문지SP
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• 제40권2호
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• pp.29-36
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• 2003

본 논문에서는 디지털 워터마킹을 이용하여 기존2차원 TV와 호환가능한 새로운 3차원 동영상 전송기법을 제안한다. 일반적으로 3차원 영상을 효과적으로 전송하기 위해 스테레오 영상간의 시간적 공간적 중복성을 이용한 동영상 전송방법을 사용하고 있다. 그러나 3차원 영상의 압축에 대한 효율성 때문에 복호화과정에서 기존의 일반 디지털 TV로는 전송된 3차원 영상의 시청이 불가능한 단점이 있다. 이러한 문제점을 개선하기 위해 제안한 방법에서는 디지털 워터마킹이 시각적으로 보이지 않는 곳에 새로운 정보를 은닉시키는 부분에 착안하여 스테레오 영상의 다른 한쪽 영상의 정보를 기준 영상의 각 채널별로 은닉하여 복호화시 3차원 영상의 복원 뿐만아니라 기존의 디지털 TV로도 시청 가능하도록 하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제13권1호
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• pp.237-253
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• 2019

For massive multiple-input multiple-output (MIMO) circumstances with time division duplex (TDD) protocol, pilot contamination becomes one of main system performance bottlenecks. This paper proposes an uplink pilot sequence assignment to alleviate this problem for spatially correlated massive MIMO circumstances. Firstly, a single-cell TDD massive MIMO model with multiple terminals in the cell is established. Then a spatial correlation between two channel response vectors is established by the large-scale fading variables and the angle of arrival (AOA) span with an infinite number of base station (BS) antennas. With this spatially correlated channel model, the expression for the achievable system capacity is derived. To optimize the achievable system capacity, a problem regarding uplink pilot assignment is proposed. In view of the exponential complexity of the exhaustive search approach, a pilot assignment algorithm corresponding to the distinct channel AOA intervals is proposed to approach the optimization solution. In addition, simulation results prove that the main pilot assignment algorithm in this paper can obtain a noticeable performance gain with limited BS antennas.