• 전자공학회논문지
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• 제54권2호
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• pp.85-91
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• 2017

렌즈의 굴절률은 빛의 파장 대역에 따라 다르다. 이로 인하여 서로 다른 파장 대역의 광선들이 다른 위치에서 초점이 맞게 되어 영상의 화질이 떨어지게 되고 에지 주변에서 색수차가 발생하게 된다. 본 논문은 컬러 영상의 색수차를 제거하기 위한 방법을 제안하였다. 컬러 채널들 기울기들의 상관관계가 높다는 이론을 기반으로 하여 컬러 채널들의 기울기 차이에 대한 비용 함수를 설계하였다. 설계된 비용 함수의 에너지를 최소화하도록 하는 해를 찾음으로써 색수차가 제거된 고화질의 컬러 영상을 추정할 수 있다. 추가적으로, 제안하는 방법은 컬러 영상뿐만 아니라 다중 분광 대역 영상에 대해서도 적용 가능하다. 실험 결과에서 제안하는 방법이 효과적으로 색수차를 제거할 수 있다는 것을 보여준다.

• 한국의류학회지
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• 제35권12호
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• pp.1486-1496
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• 2011

The present study analyzed the consumer acceptance of labels, satisfaction with cosmetics after purchase, the relationship between consumer acceptance of cosmetics labels and satisfaction with cosmetics as viewed by type of distribution channel. The study was implemented through a descriptive survey method based on a self-administered questionnaire. The sample consisted of 759 women between the ages of 21 and 49, residing in the area of Seoul, Gwangju, and Gyeonggi Province. There were significant differences in the levels of consideration of labels among consumers from each type of distribution channel. Consumers that prefer door-to-door sales consider the information about ingredients more crucial than consumers who prefer other types of distribution channels, department store consumers consider manufacturer information more important, and consumers who prefer specialty stores/chains and discount stores consider the date of manufacture less important than other types of distribution channels. Significant differences were found in consumer satisfaction with cosmetics after purchasing among consumers from each type of distribution channels. A significant relationship was found between the level of considering the product information listed on the labels and the satisfaction with the cosmetics. With respect to most of the factors, a higher level of label consideration was correlated with a higher satisfaction with cosmetics after purchase.

• Journal of the korean society of oceanography
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• 제31권1호
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• pp.7-17
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• 1996

The species composition and distribution patterns of the subtidal benthic faunal assemblage in Sokmo and Yomha Channels and Kyonggi Bay were studied in spring and fall of 1989 and correlated to some environmental variables: temperature, salinity and substrate type. For both seasons, a total of 7,779 organisms were counted belonging to 244 species. Of these, 3,647 organisms in 185 species were counted for spring (March 1989) and 4,132 in 189 species for fall (September 1989). The oyster, Cressostrea gigas and the tellinidean bivalve, Moerella rutilla were the two most abundant species in the spring, constituting 17.22%and 6.47% of the total abundance respectively. While in the fall, the barnacle, Balanus reticulatus and macrura, Ogyrides orientalis dominated comprising 13.72% and 6.87 % of the total number of individuals. Community structure analysis revealed good correlations with the variations of salinity in Yomha and Sokmo Channels and sedimentary facies in Kyonggi Bay, Korea.

• 한국통신학회논문지
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• 제33권5A호
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• pp.487-493
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• 2008

In this paper, we consider coded layered space-time architecture in MIMO-OFDM channels. Vertical Bell Lab Layered Space-Time(V-BLAST) scheme employing ordered successive interference cancellation(OSIC) algorithm provides very high spectral efficiency with low computational complexity. However, the error propagation is a major drawback constraining the overall performance of the V-BLAST system significantly. Based on this problem, we derive an improved detector using soft bit log-likelihood ratio(LLR) value. Simulation results show that the proposed detector outperforms the conventional V-BLAST scheme under spatially uncorrelated as well as correlated fading channels.

• ETRI Journal
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• 제26권6호
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• pp.622-634
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• 2004

In this paper, we discuss the design problem and the robustness of space-frequency trellis codes (SFTCs) for multiple input multiple output, orthogonal frequency division multiplexing (MIMO-OFDM) systems. We find that the channel constructed by the consecutive subcarriers of an OFDM block is a correlated fading channel with the regular correlation function of the number and time delay of the multipaths. By introducing the first-order auto-regressive model, we decompose the correlated fading channel into two independent components: a slow fading channel and a fast fading channel. Therefore, the design problem of SFTCs is converted into the joint design in both slow fading and fast fading channels. We present an improved design criterion for SFTCs. We also show that the SFTCs designed according to our criterion are robust against the multipath time delays. Simulation results are provided to confirm our theoretic analysis.

• The Journal of the Acoustical Society of Korea
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• 제21권3E호
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• pp.140-145
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• 2002

This paper introduces the downlink Eigen-beamformer with Space-Time Block Code (STBC)[1,2] employed on the MISO (Multiple Input Multiple Output) systems. The proposed scheme is acquired both transmit diversity gain from STBC and beamforming gain from Eigen-beamformer. In general, it is well described that the diversity gain be maximized when channel parameters associated to fingers are mutually independent. Major role of utilizing Eigen-beamformer is to enforce channel parameters being uncorrelated. According to this, the proposed STBC combined with Eigen-beamformer on the downlink significantly improves its performance under the spatially correlated channel. Simulation results are accomplished under three distinct channels conditioned with varying the degree of their correlations. The result indicates that our proposed scheme is good performance in spatially correlated channel.

• 한국통신학회논문지
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• 제9권1호
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• pp.18-24
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• 1984

이온충 신틸레이션 채널(transionospheric scintillation channel)에서 PSK通信시스템의 誤率을 가우스 쿼드러처積分(Gauss quadrature integration)公式의 方法을 利用하여 계산하였다. 使用한 채널 모델은 Rino의 모델로 交信信號의 포락선이 相關가우스 랜덤 과정으로 천천히 변하는 페이딩 채널이다. 신틸레이션 채널에 대한 誤率은 UHF帶의 傳送에서 실제 이온중 신틸레이션 데이터를 使用하여 계산하였다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2001년도 하계종합학술대회 논문집(1)
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• pp.121-124
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• 2001

In this paper, we propose a robust trellis coded OFDM(orthogonal frequency division multiplexing) system for wireless communications over frequency selective fading channels. Computer simulations show that the proposed system achieves the better frame error rate(FER) performance as compared with the conventional Space time coded OFDM system in the correlated channel with multiple transmitter antennas.

• 한국항행학회논문지
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• 제12권1호
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• pp.54-60
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• 2008

일반적으로 무선통신 시스템은 채널 상에서 발생하는 페이딩, 음영효과, 전파감쇠, 잡음 및 간섭 등에 의해 신호의 신뢰성이 크게 저하된다. 따라서 멀티미디어 데이터들을 열악한 무선통신 채널에서 안정적으로 전송하기 위해서는 보다 신뢰성 있는 시스템이 필요하다. 본 논문에서는 무선통신 환경에서 보다 신뢰성 있는 정보 전송을 위해 STBC의 다이버시티 이득과 STTC의 채널 효율성, 코딩 이득 및 다이버시티 이득을 동시에 갖는 STTC 기반 STBC 시스템을 고려하고 송수신기 사이의 채널 간 상관 값을 갖는 슬로우 페이딩 채널환경에서 성능을 분석하였다.

• Journal of information and communication convergence engineering
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• 제13권1호
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• pp.1-6
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• 2015

In this study, we consider visible light communication in an indoor line-of-sight environment. It has been proved that among the multiple input multiple output (MIMO) techniques, spatial modulation (SM) performs better than repetition coding (RC) and spatial multiplexing (SMP). On the basis of a combination of SM and pulse amplitude modulation (PAM), here, we propose an enhanced SM algorithm to improve the bit error rate. Traditional SM activates only one light-emitting diode (LED) at one time, and the proposed enhanced SM activates two LEDs at one time and reduces the intensity levels of PAM by half. Under the condition of a highly correlated channel, power imbalance is used to improve the algorithm performance. The comparison between the two schemes is implemented at the same signal-to-noise ratio. The simulation results illustrate that the enhanced SM outperforms the traditional SM in both highly correlated and lowly correlated channels. Furthermore, the proposed enhanced SM scheme can increase the transmission rate in most cases.