• Journal of KIISE:Software and Applications
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• v.36 no.5
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• pp.347-352
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• 2009

Nonnegative matrix factorization (NMF) is a popular method for multivariate analysis of nonnegative data, the goal of which is decompose a data matrix into a product of two factor matrices with all entries in factor matrices restricted to be nonnegative. NMF was shown to be useful in a task of clustering (especially document clustering). In this paper we present an algorithm for orthogonal nonnegative matrix factorization, where an orthogonality constraint is imposed on the nonnegative decomposition of a term-document matrix. We develop multiplicative updates directly from true gradient on Stiefel manifold, whereas existing algorithms consider additive orthogonality constraints. Experiments on several different document data sets show our orthogonal NMF algorithms perform better in a task of clustering, compared to the standard NMF and an existing orthogonal NMF.

• Journal of the Korea Convergence Society
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• v.8 no.11
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• pp.37-42
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• 2017

Over the next decade, there are estimated to be 250 billion IoT devices in the future, and a variety of new services and device markets are expected to be created via a new network connection. However, it is difficult to accommodate various sensors and IoT devices, such as product and installation environments, for existing IP/SIP/IMS cameras and video door phone. Additionally, recently, sensors and actuators that can accommodate IoT technology and standards are continually updated. In addition, this paper has developed an SIP/IMS intelligent gateway to flexibly accommodate IoT related equipments and to interface with ZigBee/Z-Wave/NFC endpoints in addition to the gateway basic functions. This intelligent gateway will contribute to the development of the IMS system to replace the VoIP system with the IMS equipment due to the growth of the IMS market.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2015.05a
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• pp.227-230
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• 2015

For analyzing and prediction of economic trends, it is necessary to collect particular economic news and stock data. Typical Web crawler to analyze the page content, collects document and extracts URL automatically. On the other hand there are forms of crawler that can collect only document of a particular topic. In order to collect economic news on a particular Web site, we need to design a crawler which could directly analyze its structure and gather data from it. The wrapper-based web crawler design is required. In this paper, we design a crawler wrapper for Economic news analysis system based on big data and implemented to collect data. we collect the data which stock data, sales data from USA auto market since 2000 with wrapper-based crawler. USA and South Korea's economic news data are also collected by wrapper-based crawler. To determining the data update frequency on the site. And periodically updated. We remove duplicate data and build a structured data set for next analysis. Primary to remove the noise data, such as advertising and public relations, etc.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.2B
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• pp.158-166
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• 2004

Address lookup is one of the most essential functions of the Internet routers and a very important feature in evaluating router performance. Due to the facts that the Internet traffic keeps growing and the number of routing table entries is continuously growing, efficient address-lookup mechanism is indispensable. In recent years, various fast address-lookup schemes have been proposed, but most of those schemes are not practical in terms of the memory size required for routing table and the complexity required in table update In this paper, we have proposed a parallel IP address lookup architecture based on multiple hashing. The proposed scheme has advantages in required memory size, the number of memory accesses, and table update. We have evaluated the performance of the proposed scheme through simulation using data from MAE-WEST router. The simulation result shows that the proposed scheme requires a single memory access for the address lookup of each route when 203kbytes of memory and a few-hundred-entry TCAM are used.

• Proceedings of the Korea Water Resources Association Conference
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• 2007.05a
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• pp.879-882
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• 2007

수문관측자료 운영 개선방안에 대한 연구(2006, 김휘린, 조효섭)에서 건설교통부 한강홍수통제소에서 수행하고 있는 수문관측자료를 대상으로 하여 관측, 기록, 전송, 품질관리, DB구축 및 정보화의 5단계로 임의 분류하고 각 단계별 현황을 파악하여 문제점을 검토하고 개선방안을 제안하였다. 이는 적극적으로 수용되어 수문관측자료 운영에 대해 개선을 시도하였으며 본 논문에서는 이를 간략히 소개하고자한다. 첫째, 관측소 점검 대장이 조사과와 전기통신과로 이분화되어 있고 각 관측소별로 점검대장이 비치되어 있으나 이를 수기로 작성하고 있으며 자료의 업데이트 및 과거점검대장의 DB 구축과 비전산화를 지적한 바 있다. 이에 '물관련시스템 DB연계 사업'을 통해 수기로 작성된 관측시설 점검대장을 전부 DB로 구축하였고 이를 총괄하여 관리 및 점검사항을 업데이트할 수 있는 관측시설 점검대장 관리 및 입력 프로그램을 구축하였고 현재 한강홍수통제소에서 시험 운영 중에 있다. 향후 보완이 끝난 후에는 낙동강, 금강, 영산강 홍수통제소에도 확대 설치 및 운영을 실시할 예정이다. 둘째, 수문자료의 품질관리에 있어서 전산시스템에 의한 완전 자동화는 실현하기가 어려울 뿐 아니라 바람직하지 못한 결과를 가져올 수 있으므로 담당자의 수동 검토 및 처리과정은 필수적이라고 논한 바 있다. 그 후 수문자료품질관리T/F팀(조사과, 전기통신과, 하천정보센터)이 구성되었고, 홍수기 오 결측자료 발생 확인, 긴급대응 촉구, 이상치 발생원인 추정 및 대책 마련 등 고품질 수문자료를 생성하기 위해 노력하였다. T/F팀 활동사항은 타홍수통제소에서도 벤치마킹이 되고 있다. 보다 정확한 댐운영자료 공유방안을 위한 관련기관과의 협력회의가 개최되어 품질관리된 자료의 정보 공유시기, 공유방식, 자료형태 등이 결정되었다. 이는 유관기관간 품질관리된 댐운영자료의 효율적인 정보 공유체계 확립을 위한 체계를 마련하는 계기라고 사료된다. 또한, 유량측정사업 결과를 익년에 반영하는 기존 방식을 개선하기 위해 유량자료관리및분석시스템(프론티어사업에서 수행, 한국건설기술연구원 개발)을 통제소내에 설치 운영을 추진하고 있다.

• Journal of Korean Society for Geospatial Information Science
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• v.16 no.3
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• pp.29-34
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• 2008

Demand for car navigation systems has been an explosive increase because of prevalence of owner-drivers, spare time spread, and so on. In addition, car navigation systems are achieving a rapid growth to be the important part of telematics industry with services such as real-time traffic information and DMB(Digital Multimedia Broadcasting). The network data, one of the composition components in car navigation systems, is most important component because that is abstract of real world road network and base data in pathfinding. However most of the car navigation systems have been stand-alone system. Thus user's network data becomes outdated according to the time passing and does not reflect the change of road information in real world. To overcome this problem, users have to update network data in car navigation systems periodically. This method is quite cumbersome process. For this reason, this study proposed a new update method to serve the difference network data on user's device and the real world in real time, and simulated to verify.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2018.10a
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• pp.304-305
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• 2018

Recently, Industrial-IoT (IIoT) solutions accounted for up to 55% in 2016 and technological innovation and various new business models are being developed. In this paper, apply IIoT device in various environments and implement an ontology system that can interwork with block type IIoT device to easily add / change / delete sensor. The proposed system consists of IIoT device, block-type module, and ontology server. When the block-type module is connected to the IIoT device, the appropriate driver is installed and the firmware is downloaded through the ontology server. Even if a block is added / changed / deleted, it can be updated automatically. Through experiments, we confirmed that the normal operation of the server and the updating and downloading of software are implemented normally.

• Journal of Digital Contents Society
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• v.18 no.2
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• pp.311-317
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• 2017

A drama, generally composed of dozens of times, is one of the most popular broadcasting program genres, and it has the characteristics that the status and interrelationships of characters are changing as time goes on and important acts affecting the story occur sporadically. Therefore, when viewers missed some times in the middle of a drama, it is difficult to understand the drama without the changed information on the characters and notable actions. This paper proposes a data service which provides the updated information of the characters and important acts based on the drama scene. The data service has the characteristics that it provides the information on the characters shown in the current drama scene, and the information about the people mentioned in the dialogue in the scene. This paper includes a general introduction to the data services, the formal definition of the drama scene identification and character information, and an DVB-SI-based method for transmitting the information to the data service.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.5B
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• pp.509-516
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• 2009

The Stream Control Transmission Protocol(SCTP) is a reliable transport layer protocol that provides several features. Multihoming is the one of the features and allows an association(SCTP's term for a connection) between two endpoints to use multiple paths. One of the paths, called a primary path, is used for initial data transmission and in the case of retransmission an alternate path is used. SCTP's current retransmission policy attempts to improve the chance of success by sending all retransmissions to an alternate destination address. However, SCTP's current retransmission policy has been shown to actually degrade performance in many circumstances. It is because that, due to Karn's algorithm, successful retransmissions on the alternate path cannot be used to update RTT(Round-Trip Time) estimation for the alternate path. In this paper we propose a scheme to avoid such performance degradation. We utilize 2bits which is not used in the flag field of DATA and SACK chunks to disambiguate original transmissions from retransmissions and to keep RTT and RTO(Retransmission Time-Out) values more accurate.

• Journal of KIISE:Databases
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• v.32 no.1
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• pp.1-11
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• 2005

An aggregation query computes aggregate information over a data cube in the query range specified by a user Existing methods based on the prefix-sum approach use an additional cube called the prefix-sum cube(PC), to store the cumulative sums of data, causing a high space overhead. This space overhead not only leads to extra costs for storage devices, but also causes additional propagations of updates and longer access time on physical devices. In this paper, we propose a new prefix-sum cube called 'SPEC' which drastically reduces the space of the PC in a large data warehouse. The SPEC decreases the update propagation caused by the dependency between values in cells of the PC. We develop an effective algorithm which finds dense sub-cubes from a large data cube. We perform an extensive experiment with respect to various dimensions of the data cube and query sizes, and examine the effectiveness and performance ot our proposed method. Experimental results show that the SPEC significantly reduces the space of the PC while maintaining a reasonable query performance.