• Journal of Satellite, Information and Communications
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• v.4 no.2
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• pp.46-51
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• 2009

This paper addresses the calculation method of the interference produced between the LEO(Low Earth Orbit) satellite constellation and Terrestrial system operating in the same frequency and area. We describes the procedure used in the numerical computation of the statistics of the total interference produced by interference system. The presented results are applied for mutual protection of LEO satellite constellation and FS system during system design phase.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2013.06a
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• pp.29-31
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• 2013

본 논문에서는 기존라디오(primary) 네트워크와 스펙트럼을 공유하는(spectrum sharing) 인지라디오(cognitive radio) 네트워크에서 비재생적(non-regenerative) 다중안테나 중계 (relay) 시스템을 위한 소스(source) 및 중계기 프리코딩(precoding) 기법을 제안한다. 제안된 기법은 소스와 중계기 프리코딩 행렬의 최적해를 구하기 위해 QCQP(Quadratically Constrained Quadratic Programming) 문제를 통해 구한다. 제안된 기법은 기존라디오 수신기에서의 간섭세기 제한을 만족하면서 낮은 MSE(Mean squared error)와 높은 MI(Mutual Information)를 달성함을 모의실험결과를 통해 보인다. 또한 아주 빠른 속도로 최적해로 수렴함을 보이고 있다.

• Annual Conference on Human and Language Technology
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• 1992.10a
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• pp.39-49
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• 1992

시소러스를 작성하기 위해 시소러스 작성자가 고려래야 하는 문제는 단어간의 개념 관계이다. 단어간의 관개는 계층구조에 정의된 개념을 기반으로 분석하여 하향식으로 시소러스를 작성하는 것이 일반적이다. 이러한 방식은 작성자에 의존적이므로 시소러스의 정확도를 보장할 수 없고 주관적인 성향을 가진다. 그래서 Corpus에서 자동으로 개념 및 개념 관계를 추출하는 상향식 방법들이 다양하게 시도되고 있다. 본 논문에서는 시소러스 작성을 위한 자동 개념 획득 도구를 설계, 구현하였다. Mutual Information이라는 방법을 이용하여 공기 정보(Collocation)를 정량화하고 이를 통하여 단어간의 개념관계의 크기를 측정한 후 개념 관계의 크기(MI 값)가 큰 값을 선택하여 개념 화일을 작성한다. 실험 결과로 얻은 개념 화일은 두 개념간의 밀접도를 나타내므로 시소러스 작성에 매우 유용하다.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.22.1-22
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• 2001

In this paper we present Multiple-Channel Active Noise Control[ANC] system by employing Independent Component Analysis[ICA] and Adaptive Network Fuzzy Inference System[ANFIS]. ICA is widely used in signal processing and communication and it use prewhiting and appropriate choice of non-linearities, ICA can separate mixed signal. ANFIS controller is trained with the hybrid learning algorithm to optimize its parameters for adaptively canceling noise. This new method which minimizes a statistical dependency of mutual information(MI) in mixed low frequency noise signal and there is no need to secondary path modeling. The proposed implementations achieve more powerful and stable noise reduction than Filtered-X LMS algorithms which is needed for LTI assumption and precise secondary error

• Journal of Korea Multimedia Society
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• v.13 no.2
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• pp.225-236
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• 2010

This study proposes a method for the recognition of emergency situation according to the bimodal information of camera image sensor and gravity sensor. This method can recognize emergency condition by mutual cooperation and compensation between sensors even when one of the sensors malfunction, the user does not carry gravity sensor, or in the place like bathroom where it is hard to acquire camera images. This paper implemented HMM(Hidden Markov Model) based learning and recognition algorithm to recognize actions such as walking, sitting on floor, sitting at sofa, lying and fainting motions. Recognition rate was enhanced when image feature vectors and gravity feature vectors are combined in learning and recognition process. Also, this method maintains high recognition rate by detecting moving object through adaptive background model even in various illumination changes.

• Korean Journal of Remote Sensing
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• v.37 no.3
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• pp.475-491
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• 2021

With the recent increase in available high-resolution (< ~1 m) satellite SAR images, the demand for precise registration of SAR images is increasing in various fields including change detection. The registration between high-resolution SAR images acquired in different look angle is difficult due to speckle noise and geometric distortion caused by the characteristics of SAR images. In this study, registration is performed in two stages, coarse and fine, using the x-band SAR data imaged at staring spotlight mode of TerraSAR-X. For the coarse registration, a method combining the adaptive sampling method and SAR-SIFT (Scale Invariant Feature Transform) is applied, and three rigid methods (NCC: Normalized Cross Correlation, Phase Congruency-NCC, MI: Mutual Information) and one non-rigid (Gefolki: Geoscience extended Flow Optical Flow Lucas-Kanade Iterative), for the fine registration stage, was performed for performance comparison. The results were compared by using RMSE (Root Mean Square Error) and FSIM (Feature Similarity) index, and all rigid models showed poor results in all image combinations. It is confirmed that the rigid models have a large registration error in the rugged terrain area. As a result of applying the Gefolki algorithm, it was confirmed that the RMSE of Gefolki showed the best result as a 1~3 pixels, and the FSIM index also obtained a higher value than 0.02~0.03 compared to other rigid methods. It was confirmed that the mis-registration due to terrain effect could be sufficiently reduced by the Gefolki algorithm.

• Journal of the Korean Society for Library and Information Science
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• v.39 no.1
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• pp.45-58
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• 2005

This Paper is a comparative study of feature selection methods for Korean web documents clustering. First, we focused on how the term feature and the co-link of web documents affect clustering performance. We clustered web documents by native term feature, co-link and both, and compared the output results with the originally allocated category. And we selected term features for each category using $X^2$, Information Gain (IG), and Mutual Information (MI) from training documents, and applied these features to other experimental documents. In addition we suggested a new method named Max Feature Selection, which selects terms that have the maximum count for a category in each experimental document, and applied $X^2$ (or MI or IG) values to each term instead of term frequency of documents, and clustered them. In the results, $X^2$ shows a better performance than IG or MI, but the difference appears to be slight. But when we applied the Max Feature Selection Method, the clustering Performance improved notably. Max Feature Selection is a simple but effective means of feature space reduction and shows powerful performance for Korean web document clustering.

• Archives of design research
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• v.18 no.1 s.59
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• pp.185-194
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• 2005

The objectives of this research are to examine the relationships among designers' characteristics, mutual communication, conflicts between CI designer and client, to test the impacts of conflicts and four type of resolution strategies on the performance of CI development, and to recommend proper strategies for successful CI process and output management. The survey results show as follows. First, CI designers' confidentiality on clients' internal information and creative designing ability were found to affect mutual communication between them. Second, proper communication was found to lessen the conflict level which in turn yielded the positive performance of CI development, especially for the clients' side. Third, it is suggested that the conflict level be first reduced and conflict resolution strategies be applied depending upon the conflict level and related party of designer or client position, respectively.

• Journal of Multimedia Information System
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• v.9 no.1
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• pp.51-60
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• 2022

This paper raised the need to examine how the online education environment triggered by COVID-19 and the smart learning environment can be established in consideration of the improvement of education and learning through learning analysis. Many studies are being conducted in Korea, and the Ministry of Education is continuously striving to build a smart school by promoting strategies for promoting smart education on the way to a talent powerhouse. Nevertheless, there is no unified definition of smart learning, and it can be seen as customized (individualized) learning using smart devices. However, most of the discussions on the construction of smart schools so far have limitations in that they are limited to physical spaces. Accordingly, the opinions of teachers and learners were not sufficiently reflected in the establishment of the facility. This study intends to study smart learning in various departments. In addition, the subjects students in charge of the co-researcher of this study were analyzed. The total number of subjects was 951, and 434 responded to this study survey. In addition, students were well accepting the online environment, and in the future, regardless of COVID-19, research will be presented to improve mutual communication between professors and students in smart learning.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.16 no.9
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• pp.1983-1989
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• 2012

The IEEE 802.1x standard provides an architectural framework which can be used various authentication methods. But, IEEE 802.1x also has vulnerabilities about the DoS(Denial of Service), the session hijacking and the MiM(Man in the Middle) attack due to caused by structural of authentication protocol. In this paper, we propose a WLAN system which can offer safety communication by complement of IEEE 802.1x vulnerabilities. The WLAN system accomplishes mutual authentications between authentication servers, clients and the AP using PKI and prevents an illegal user from intervening in communication to disguise oneself as a client, the AP or authentication servers. Also, we guarantee the safety of the communication by the Dynamic WEP key distribution between clients and the AP.