• Journal of the Institute of Electronics Engineers of Korea SP
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• v.38 no.5
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• pp.548-555
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• 2001

In this paper, we proposed a HVS(human visual system) model-based digital image watermarking which is not only invariant to rotation and translation but also more robust to lossy compression, cropping, and scaling as compared to the conventional method. Fourier transform and log-polar mapping is used to make the proposed algorithm invariant to rotation and translation, and in addition, watermark energy is embedded maximally based on spatial frequency sensitivity of HVS without the deterioration of the invisibility. As a result, the robustness of watermarking is improved both in general image processing operations such as cropping, low pass filtering, and lossy compression and in geometrical transforms such as rotation, translation, and scaling. And, by disjoint embedding of the watermark and the template without intersection, the deterioration of invisibility and robustness is prevented. Experimental results show that proposed watermarking is about 30~75 [%] more robust af compared to the conventional methods.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2003.05a
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• pp.59-263
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• 2003

정보통신의 비약적인 발전에 힘입어 멀티미디어 데이터는 언제 어디서든 전송 받거나 공유할 수 있게 되었다. 아날로그 형태에서 디지털의 아날로그를 형태로 빠르게 대체되고 있으며, 디지털로 신호를 표현하는 방법은 기존 사용하여 표현하는 방법에 비해 많은 장점을 가지고 있다. 하지만 디지털로 된 데이터는 언제 어디서든 대단위 복제가 가능하다. 즉, 저작권 침해, 불법 복제 및 배포, 손쉽게 위조할 수 있다는 점이 그것이다. 디지털 컨텐츠의 불법 복제와 유통은 저작자의 창작 의욕과 수입원을 차단하는 매우 중요한 문제이며, 이를 방지하기 위해서 멀티미디어 데이터의 저작권을 가진 소유자가 원하는 정보를 삽입함으로써 데이터의 저작권 보호와 복사 방지 및 불법적인 유통을 막고자 하는 기술이 개발되고 있다. 디지털 영상 정보의 보호를 위해 디지털 영상의 불법적인 내용 조작을 막고, 영상의 소유권을 보장할 수 있는 방법으로 디지털 워터마크(Digital Watermark)가 있다. 디지털 워터마크는 공개키 알고리즘이나 방화벽 등으로 해독된 영상에 대하여 부가적인 보호를 제공한다. 디지털 영상에 대한 저작권 정보, 배포자 정보 그리고 사용자 정보를 영상에 삽입함으로써 훗날 법적인 문제가 발생하였을 때 해결책을 제시할 수 있다. 본 논문에서는 디지털 영상 데이터의 정보 보호를 위해 주파수 영역에서의 웨이브릿 변환(Wavelet Transform)을 이용한 이미지 적응 디지털 워터마킹(Image-Adaptive Digital Watermarking) 방법을 제안한다. 이미지 적응 웨이브릿(Image-Adaptive Wavelet)은 영상을 주파수적으로 분해하면서 각 대역들의 공간 영역에서의 정보를 함께 지니고 JND(Just noticeable difference)을 포함한다. 이미지 적응 웨이브릿의 이러한 특성을 이용하여 다해상도 분해하고, 손실 압축(toss Compression) 이나 필터링(Filtering), 잡음(Noise) 등에 크게 영향받는 저주파 성분과 인간의 시각적으로 큰 의미를 갖는 고주파 성분의 특성을 이용하여 워터마크를 삽입한다.

• The Journal of the Korea Contents Association
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• v.20 no.10
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• pp.715-725
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• 2020

In this paper, we propose an optimization scheme for a k-Nearest Neighbor(k-NN) query, which finds k objects closest to the query in the high dimensional feature vectors. The k-NN query is converted and processed into a range query based on the range that is likely to contain k data. In this paper, we propose an optimization scheme using DNN model to derive an optimal range that can reduce processing cost and accelerate search speed. The entire system of the proposed scheme is composed of online and offline modules. In the online module, a query is actually processed when it is issued from a client. In the offline module, an optimal range is derived for the query by using the DNN model and is delivered to the online module. It is shown through various performance evaluations that the proposed scheme outperforms the existing schemes.

• Journal of the Korean BIBLIA Society for library and Information Science
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• v.23 no.4
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• pp.283-308
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• 2012

With explosive growth of information by recent advancements in information technology and the Internet, users need a method to acquire appropriate information. To solve this problem, an information retrieval and filtering system was developed as an important tool for users. Also, users and service providers are growing more and more interested in personalized information recommendation. This study designed and implemented personalized information recommendation system based on AR as a method to provide positive information service for information users as a method to provide positive information service. To achieve the goal, the proposed method overcomes the weaknesses of existing systems, by providing a personalized recommendation method for contents that works in a large-scaled data and user environment. This study based on the proposed method to extract rules from log files showing users' behavior provides an effective framework to extract Association Rule.

• The KIPS Transactions:PartD
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• v.9D no.6
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• pp.1009-1016
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• 2002

We design and implement a new case-based recommender system using implicit rating information for a digital content site. Our system consists of the User Profile Generation module, the Similarity Evaluation and Recommendation module, and the Personalized Mailing module. In the User Profile Generation Module, we define intra-attribute and inter-attribute weight deriver from own's past interests of a user stored in the access logs to extract individual preferences for a content. A new similarity function is presented in the Similarity Evaluation and Recommendation Module to estimate similarities between new items set and the user profile. The Personalized Mailing Module sends individual recommended mails that are transformed into platform-independent XML document format to users. To verify the efficiency of our system, we have performed experimental comparisons between the proposed model and the collaborative filtering technique by mean absolute error (MAE) and receiver operating characteristic (ROC) values. The results show that the proposed model is more efficient than the traditional collaborative filtering technique.

• Journal of KIISE:Databases
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• v.32 no.5
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• pp.558-566
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• 2005

The XML is the new standard fir data representation and exchange on the Internet. In this paper, we describe a new approach for evaluating a path-oriented query against XML document. In our approach, we propose the Parallel Match Indexing Fabric to speed up evaluation of path-oriented query using path signature and design the parallel match algorithm to perform a match process between a path signature of input query and path signatures of elements stored in the database. To construct a structure of the parallel match indexing, we first make the binary tie for all path signatures on an XML document and then which trie is transformed to the Parallel Match Indexing Fabric. Also we use the Parallel Match Indexing Fabric and a parallel match algorithm for executing a search operation of a path-oriented query. In our proposed approach, Time complexity of the algorithm is proportional to the logarithm of the number of path signatures in the XML document.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.8 no.3
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• pp.563-568
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• 2007

We propose the computation reduction method of real root method that is used in the EVRC(Enhanced Variable Rate Codec) system. The real root method is that if polynomial equations have the real roots, we are able to find those and transform them into LSP. However, this method takes much time to compute, because the root searching is processed sequentially in frequency region. But, the important characteristic of LSP is that most of coefficients are occurred in specific frequency region. So, to reduce the computation time of real root, we used the met scale that is linear below 1kHz and logarithmic above. In order to compare real root method with proposed method, we measured the following two. First, we compared the position of transformed LSP(Line Spectrum Pairs) parameters in the proposed method with these of real root method. Second, we measured how long computation time is reduced. The experimental result is that the searching time was reduced by about 48% in average without the change of LSP parameters.

• Journal of KIISE:Computing Practices and Letters
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• v.11 no.1
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• pp.69-80
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• 2005

Recent popularity of web-ready mobile devices such as PDA and cellphone has made mobile Internet access very popular. However, most of existing Web contents and services are optimized for desktop computing environment and not well suited for mobile devices. Considering different system features of mobile devices such as small display and limited input capability, an alternative scheme to access the Web efficiently is required. On the other hand, personalization plays an important role in the tailored access to the Web contents and services. In this paper, we propose a proxy- based personalization scheme of Web service pages for mobile users. For that purpose, in addition to log data. service related features of Web pages are considered for the correct identification of popular services. It automatically provides mobile users with the tailored list of Web services well suited for diverse mobile devices. Consequently, mobile users can utilize customized Web services with minimum navigation on the mobile devices with limited capability. In order to show its effectiveness, we have performed several experiments on the prototype system and reported some of the results.

• Geophysics and Geophysical Exploration
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• v.1 no.3
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• pp.183-187
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• 1998

Seismic waveform estimation is based on the assumption that the seismic trace tying a well is one dimensional convolution of the propagating seismic waveform and the reflectivity series derived from well logs (sonic and density). With this assumption, the waveform embedded in a seismic trace can be estimated using a Wiener match filter. In this paper, I experimented a preprocessing procedure that applies both on the seismic trace and on the reflectivity series. The procedure is based on the assumption that the travel time can be estimated better from the seismic trace and that the instantaneous reflectivity values can be measured better on the well log. Thus the procedure is, 1) start-time adjustment and dynamic differential stretches are applied on the sonic log, and 2) seismic amplitudes are balanced such that the low frequency part of the seismic are matched to that of the reflectivities derived from well logs.

• The Journal of the Acoustical Society of Korea
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• v.32 no.3
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• pp.269-278
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• 2013

The speech recording of the National Archives of Korea contains very important traces which represent modern times of Korea. But the way to be recorded by analogue is easily contaminated as time goes by. So it has to be digitalized for management and services. Consequently, restoration method of distorted speech is needed. We propose the four classes for each distortion kind and apply restoration algorithms for the cases of speech level, stationary noise and abrupt noise. As a result, speech volume adjusts to -26 dBov for only on the speech region and SNR improves above 10dB. Especially, conventional way to remove the noise is almost impossible because we need to listen to all of them but it can be more effective by adaptation of auto restoration algorithm.