• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2010.06a
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• pp.53-60
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• 2010

위치 기반 서비스(Location-Based Services: LBS)에서 질의 요청자가 자신의 위치 정보와 원하는 질의를 전송하면, 위치 기반 서버는 이를 기반으로 질의를 처리하고 결과를 전송한다. 이 때 질의 요청자는 자신의 정확한 위치 좌표를 서버에 전송하기 때문에 개인 정보가 악용될 수 있는 위험에 노출된다. 이러한 문제를 해결하기 위하여 제안된 연구는 크게 Location Clocking 기법과 Private Information Retrieval(PIR) 기법으로 분류된다. Location Cloaking 기법은 사용자의 위치 좌표를 k-1개의 다른 사용자와 함께 묶어 하나의 Cloaking 영역을 생성하고 이를 바탕으로 질의를 처리한다. 그러나 영역에 대한 질의 후보 집합을 결과로 전송하므로 사용자에게 노출되는 POI 수가 증가하는 문제점을 지닌다. PIR은 암호화 기법으로 위치 기반 서버나 공격자에게 사용자의 위치와 질의 타입을 드러내지 않고 질의를 수행한다. 그러나 암호화 된 질의 결과로 사용자에게 데이터 전체를 전송하기 때문에 막대한 통신비용을 초래한다. 따라서 본 논문에서는 Location Cloakng과 PIR 기법의 장점을 결합하여 사용자의 개인 정보와 위치 기반 서버의 POI 정보 보호를 고려한 Approximate k-최근접점 질의 처리 알고리즘을 제안한다. 질의 전송시, 질의 요청자는 Cloaking 영역을 생성하여 위치 좌표를 감추고, 질의 결과 전송 시 Cloaking 영역에 제한된 PIR 프로토콜을 적용한다. 또한 k-최근접점 질의 수행시, 반환되는 POI의 수를 최소화하고, 정확도 높은 질의 결과를 만족하기 위해 Overlapping parameter를 적용한 색인 기법을 제안한다.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2006.04a
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• pp.208-215
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• 2006

This study provides a new operation strategy which can guarantee the data consistency of engineering information among the various intelligent information systems. We present the strategies for the operation of bridges engineering information and the construction methodology of integrated database. The two core standard techniques are adopted to construct the integrated database. One of these standards is the Standard for the Exchange of Product Model Data (STEP) for CAD/CAE information and the other is the Extensible Markup Language (XML) for engineering document information. This study can transform a document me into a data type for web-based application modules which assist end-users in searching and retrieval of engineering document data. In addition, relaying algorithm is developed to integrate the two different information, e.g. CAD/CAE information and engineering document information. The pilot application modules for management and maintenance of existing bridge are also developed to show application of the strategy.

• Journal of Korea Multimedia Society
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• v.11 no.8
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• pp.1043-1050
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• 2008

XML has become a standard for data representation and exchange on the Internet. With a large number of XML documents on the Web, there is an increasing need to automatically process those structurally rich documents for information retrieval, document management, and data mining applications. In this paper, we propose a new method to measure the similarity between XML documents by considering their structures and contents. The similarity of document's structure is found by a simple string matching technique and that of document's contents is found by weights taking into account of the names and positions of elements. The overall algorithm runs in time that is linear in the combined size of the two documents involved in comparison evaluation.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.390-395
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• 2009

The robustness of audio fingerprinting system in a noisy environment is a principal challenge in the area of content-based audio retrieval. The selected feature for the audio fingerprints must be robust in a noisy environment and the computational complexity of the searching algorithm must be low enough to be executed in real-time. The audio fingerprint proposed by Philips uses expanded hash table lookup to compensate errors introduced by noise. The expanded hash table lookup increases the searching complexity by a factor of 33 times the degree of expansion defined by the hamming distance. We propose a new method to improve noise robustness of audio fingerprinting in noise environment using predominant pitch which reduces the bit error of created hash values. The sub-fingerprint of our approach method is computed in each time frames of audio. The time frame is transformed into the frequency domain using FFT. The obtained audio spectrum is divided into 33 critical bands. Finally, the 32-bit hash value is computed by difference of each bands of energy. And only store bits near predominant pitch. Predominant pitches are extracted in each time frames of audio. The extraction process consists of harmonic enhancement, harmonic summation and selecting a band among critical bands.

• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.57-60
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• 2007

Monthly mean data of ${\AA}ngstr{\ddot{o}}m$ exponent and Aerosol optical thickness (AOT) from Sea-viewing Wide Field-of-view Sensor (SeaWiFS) measurements over the East Asian waters were analyzed. Increasing trend of the satellite-derived ${\AA}ngstr{\ddot{o}}m$ exponent from 1998 to 2004 was found while AOT mean was observed stable during the same period. The trend of ${\AA}ngstr{\ddot{o}}m$ exponent is then interpreted as increase in fraction of small aerosol particles to give quantitative estimates on the variability of aerosols. The mean increase is evaluated to be $4{\sim}5%$ over the 7-year period in terms of the contribution of small particles to the total AOT, or sub-micron fraction (SMF). Possibilities of the observed trend arising from the sensor calibration or algorithm performance are carefully checked, which confirm our belief that this observed trend is rather a real fact than an artifact due to data processing. Another time series of SMF data (2000-2005) estimated from the fine-mode fraction (FMF) of Moderate Resolution Imaging Spectroradiometer (MODIS) supports this observation yet with different calibration system and retrieval algorithms.

• Journal of Internet Computing and Services
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• v.10 no.4
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• pp.45-54
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• 2009

In this paper we propose a new approach that recognizes the similar categories by weighting distinctive features. The approach is based on the PLSA that is one of the effective methods for the object categorization. PLSA is introduced from the information retrieval of text domain. PLSA, unsupervised method, shows impressive performance of category recognition. However, it shows relatively low performance for the similar categories which have the analog distribution of the features. In this paper, we consider the effective object categorization for the similar categories by weighting the mainly distinctive features. We present that the proposed algorithm, weighted PLSA, recognizes similar categories. Our method shows better results than the standard PLSA.

• Journal of Information Science Theory and Practice
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• v.8 no.2
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• pp.6-17
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• 2020

Word similarity is often measured to enhance system performance in the information retrieval field and other related areas. This paper reports on an experimental comparison of values for word similarity measures that were computed based on 50 intentionally selected words from a Reuters corpus. There were three targets, including (1) co-occurrence-based similarity measures (for which a co-occurrence frequency is counted as the number of documents or sentences), (2) context-based distributional similarity measures obtained from a latent Dirichlet allocation (LDA), nonnegative matrix factorization (NMF), and Word2Vec algorithm, and (3) similarity measures computed from the tf-idf weights of each word according to a vector space model (VSM). Here, a Pearson correlation coefficient for a pair of VSM-based similarity measures and co-occurrence-based similarity measures according to the number of documents was highest. Group-average agglomerative hierarchical clustering was also applied to similarity matrices computed by individual measures. An evaluation of the cluster sets according to an answer set revealed that VSM- and LDA-based similarity measures performed best.

• Journal of Communications and Networks
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• v.17 no.3
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• pp.306-320
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• 2015

Due to an explosive growth in services running in different datacenters, there is need for service selection and routing to deliver user requests to the best service instance. In current solutions, it is generally the client that must first select a datacenter to forward the request to before an internal load-balancer of the selected datacenter can select the optimal instance. An optimal selection requires knowledge of both network and server characteristics, making clients less suitable to make this decision. Information-Centric Networking (ICN) research solved a similar selection problem for static data retrieval by integrating content delivery as a native network feature. We address the selection problem for services by extending the ICN-principles for services. In this paper we present Queue and Latency, a network-driven service selection algorithm which maps user demand to service instances, taking into account both network and server metrics. To reduce the size of service router forwarding tables, we present a statistical method to approximate an optimal load distribution with minimized router state required. Simulation results show that our statistical routing approach approximates the average system response time of source-based routing with minimized state in forwarding tables.

• The KIPS Transactions:PartD
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• v.8D no.3
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• pp.211-220
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• 2001

A planning agent supporting customers plays a distinguished role in internet marketplaces. Although several internet marketplaces have been built with the maturity of tools based on internet and distributed technologies, there has been no actual study up to now with respect to the implementation of the planning agent. This paper describes the design and implementation of an XML-based planning agent for internet marketplaces. Since implementing internet marketplaces encounter problems similar to those in other fields such as multidatabase or workflow management systems, we first compare those features. Next we identify functions and roles of the planning agent. The planning agent is implemented using COM+, ASP, and XML, and demonstrated using real data used in an existing system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.7A
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• pp.1044-1049
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• 2000

Projection that can be used as a feature for image representation, includes much available informations such as approximated shape and location. But when we retrieve image using it, there are some disadvantage such as requiring much index data and making different length of projected vector for differenr image size. In order to overcome these problems, we propose a method of using block variance for the projected vector. We use block variance of the projection vector to localize the characteristics of image and to reduce the number of index data in database. Proposed algorithm can make use of statistical advantage through database including various size of images and be executed with fast response time in implementation.