• KSII Transactions on Internet and Information Systems (TIIS)
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• 제6권12호
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• pp.3061-3080
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• 2012

To improve the sensing performance, cooperation among secondary users can be utilized to collect space diversity. In this paper, we focus on the optimization of cooperative spectrum sensing in which multiple cognitive users efficiently cooperate to achieve superior detection accuracy with minimum sensing error probability in multiple cross-over cognitive radio networks. The analysis focuses on two fusion strategies: soft information fusion and hard information fusion. Under soft information fusion, the optimal threshold of the energy detector is derived in both noncooperative single-user and cooperative multiuser sensing scenarios. Under hard information fusion, the optimal randomized rule and the optimal decision threshold are derived according to the rule of minimum sensing error (MSE). MSE rule shows better performance on improving the final false alarm and detection probability simultaneously. By simulations, our proposed strategy optimizes the sensing performance for each cognitive user which is randomly distributed in the multiple cross-over cognitive radio networks.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제4권6호
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• pp.1023-1041
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• 2010

In cognitive radio networks, cooperative spectrum sensing schemes are proposed to improve the performance of detecting licensees by secondary users. Commonly, the cooperative sensing can be realized by means of hard decision fusion (HDF) or soft decision fusion (SDF) schemes. The SDF schemes are superior to the HDF ones in terms of the detection performance whereas the HDF schemes are outperforming the SDF ones when the traffic overhead is taken into account. In this paper, a hybrid SFD-HDF cluster-based approach is developed to jointly exploit the advantages of SFD and HDF schemes. Different SDF schemes have been proposed and compared within a given cluster whereas the OR-rule base HDF scheme is applied to combine the decisions reported by cluster headers to a common receiver or base station. The computer simulations show promising results as the performance of the proposed scenario of hybridizing soft and hard fusion schemes is significantly outperforming other different combinations of conventional SDF and HDF schemes while it noticeably reduces the network traffic overhead.

• Journal of the Korean Data and Information Science Society
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• 제16권4호
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• pp.879-888
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• 2005

Fashion is hard to expect owing to the rapid change in accordance with consumer taste and environment, and has a tendency toward variety and individuality. Especially street fashion of 21st century is not being regarded as one of the subcultures but is playing an important role as a fountainhead of fashion trend. Therefore, Searching and analyzing street fashions helps us to understand the popular fashions of the next season and also it is important in understanding the consumer fashion sense and commercial area. So, we need to understand fashion styles quantitatively and qualitatively by providing visual data and dividing images. There are many kinds of data in street fashion information. The purpose of this study is to design and implementation for street fashion information analysis system using data fusion. We can show visual information of customer's viewpoint because the system can analyze the fused data for image data and survey data.

• 반도체디스플레이기술학회지
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• 제21권4호
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• pp.53-58
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• 2022

Shape changes of hard mask play a key role in the aspect ratio dependent etch (ARDE). For etch process using high density and energy ions, deformation of hard mask shape becomes more severe, and high aspect ratio (HAR) etch profile is distorted. In this study, polygonal geometric model for shape-deformation of amorphous carbon layered hard mask is suggested to control etch profile during the process. Mask shape is modeled with polygonal geometry consisting of trapezoids and rectangles, and it provides dynamic information about angles of facets and etched width and height of remained mask shape, providing important features for real-time HAR etch profiling.

• 한국컴퓨터정보학회논문지
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• 제15권11호
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• pp.47-56
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• 2010

항행중인 선박은 GPS, AIS, ECDIS, ARPA Radar 등 다양한 해양 장비를 통해 선내 외 상황에 대한 여러 정보들을 전달받고, 항해사는 이러한 다양한 정보를 이용하여 자선박의 항행 안전 상황을 인식 및 예측한다. 하지만 그로 인해 항해사의 장비 주시에 대한 업무 부담이 이전보다 증가하였으며, 때로는 장비 간 정보의 불일치가 발생하여 항해사를 혼란시키기도 한다. 이전 연구에서 이러한 문제를 해결하기 위해 항해사를 보조할수 있는 지능형 항행안전 정보 시스템의 개념모델과 CF(Certainty Factor)전문가 시스템을 이용한 그 개념모델의 예를 보인 바 있다. 정보 융합 기술에는 다양한 추론 기술들이 요구되는데 CF전문가 시스템만으로는 항해사의 의사결정과 같이 애매하고 불명확한 요소를 반영할 수 없다. 이 연구에서는 불명확한 요소를 반영할 수 있는 퍼지 전문가 시스템을 이용한 항행 정보 융합 방법을 제안하고, 제안된 방법을 설계 및 구현한 후 특정 시나리오에 대한 실행 예를 보임으로써 항행 정보 융합 시스템에 퍼지 전문가 시스템을 활용하는 것의 타당성을 보인다.

• 대한원격탐사학회지
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• 제22권1호
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• pp.75-85
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• 2006

This paper has dealt with a data fusion for the problem of land-cover classification using multisensor imagery. Dempster-Shafer evidence theory has been employed to combine the information extracted from the multiple data of same site. The Dempster-Shafer's approach has two important advantages for remote sensing application: one is that it enables to consider a compound class which consists of several land-cover types and the other is that the incompleteness of each sensor data due to cloud-cover can be modeled for the fusion process. The image classification based on the Dempster-Shafer theory usually assumes that each sensor is represented by a single channel. The evidential approach to image classification, which utilizes a mass function obtained under the assumption of class-independent beta distribution, has been discussed for the multiple sets of mutichannel data acquired from different sensors. The proposed method has applied to the KOMPSAT-1 EOC panchromatic imagery and LANDSAT ETM+ data, which were acquired over Yongin/Nuengpyung area of Korean peninsula. The experiment has shown that it is greatly effective on the applications in which it is hard to find homogeneous regions represented by a single land-cover type in training process.

• 한국측량학회:학술대회논문집
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• 한국측량학회 2002년도 추계학술발표회 논문집
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• pp.219-223
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• 2002

영상융합에 관한 여러 가지 기법들이 지금까지 연구되고 있다. 하지만 몇몇 기법들은 복합한 이론 배경으로 여러 단계를 거쳐야 하기에 적용이 쉽지 않은 경우도 있다. 본 연구에서는 현재까지 가장 좋은 방법으로 알려진 웨이블릿 변환기법을 다른 기존의 방법과 비교 분석하고자 한다. 이를 위하여 서로 다른 분광특성 정보를 중심으로 테스트하기 위해 4개의 지역으로 절취하였다. 그 결과 절취후 처리결과와 전체영상을 처리한 결과는 수계지역을 제외하고는 큰 차이는 없었으며 대부분의 지역에서 웨이블릿 방법이 우수함을 알 수 있었다. Multiplicative 방법도 비교적 좋은 결과를 보여주었다.

• Journal of Information Processing Systems
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• 제15권3호
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• pp.604-615
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• 2019

Single-user spectrum sensing is susceptible to multipath effects, shadow effects, hidden terminals and other unfavorable factors, leading to misjudgment of perceived results. In order to increase the detection accuracy and reduce spectrum sensing cost, we propose an adaptive cooperative sensing strategy based on an estimated signal-to-noise ratio (SNR). Which can adaptive select different sensing strategy during the local sensing phase. When the estimated SNR is higher than the selection threshold, adaptive double threshold energy detector (ED) is implemented, otherwise cyclostationary feature detector is performed. Due to the fact that only a better sensing strategy is implemented in a period, the detection accuracy is improved under the condition of low SNR with low complexity. The local sensing node transmits the perceived results through the control channel to the fusion center (FC), and uses voting rule to make the hard decision. Thus the transmission bandwidth is effectively saved. Simulation results show that the proposed scheme can effectively improve the system detection probability, shorten the average sensing time, and has better robustness without largely increasing the costs of sensing system.

• Journal of Communications and Networks
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• 제14권5호
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• pp.471-480
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• 2012

Reliable detection of primary user activity increases the opportunity to access temporarily unused bands and prevents harmful interference to the primary system. By extracting a global decision from local sensing results, cooperative sensing achieves high reliability against multipath fading. For the effective combining of sensing results, which is generalized by a likelihood ratio test, the fusion center should learn some parameters, such as the probabilities of primary transmission, false alarm, and detection at the local sensors. During the training period in supervised learning, the on/off log of primary transmission serves as the output label of decision statistics from the local sensor. In this paper, we extend unsupervised learning techniques with an expectation maximization algorithm for cooperative spectrum sensing, which does not require an external primary transmission log. Local sensors report binary hard decisions to the fusion center and adjust their operating points to enhance learning performance. Increasing the number of sensors, the joint-expectation step makes a confident classification on the primary transmission as in the supervised learning. Thereby, the proposed scheme provides accurate parameter estimates and a fast convergence rate even in low signal-to-noise ratio regimes, where the primary signal is dominated by the noise at the local sensors.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2016년도 추계학술대회
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• pp.792-793
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• 2016

최근 의료시스템과 정보통신기술을 융합하여 언제 어디서나 제약을 받지 않고 사용자의 생체정보를 측정하는 웨어러블에 대한 연구가 진행되고 있다. 그러나 기존의 웨어러블 기기는 측정된 생체정보를 모니터링 할뿐 사용자가 위급한상황이 발생할 경우에 대한 대처는 미흡한 실정이다. 본 논문에서는 이러한 문제점을 해결하기 위해 생체정보를 측정하는 센서들과 알고리즘을 활용하여 사용자의 상태를 식별하는 시스템을 제안한다. 이를 통해 사용자가 낙상이나 넘어짐 같은 위험상황이 발생할 경우 지정된 보호자에게 긴급 알림 메시지를 전송하여 위험상황을 신속하게 대처할 수 있을 것으로 사료된다.