• Journal of KIISE:Computer Systems and Theory
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• v.27 no.5
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• pp.464-474
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• 2000

All-to-all personalized communication, or complete exchange, is at the heart of numerous applications, such as matrix transposition, fast Fourier Transform(FFT), and distributed table lookup.We present an efficient all-to-all personalized communication algorithm for a 2D torus inwormhole-routed networks. Our complete exchange algorithm adopts divide-and-conquer approach toreduce the number of start-up latency significantly, which is a good metric for network performancein wormhole networks. First, we divide the whole network into 2x2 basic cells, After speciallydesignated nodes called master nodes have collected messages to transmit to the rest of the basic cell,only master nodes perform complete exchange with reduced network size, N/2 x N/2. When finishedwith this complete exchange in master nodes, these nodes distribute messages to the rest of the masternode, which results in the desired complete exchange communication. After we present our algorithms,we analyze time complexities and compare our algorithms with several previous algorithms. And weshow that our algorithm is efficient by a factor of 2 in the required start-up time which means thatour algorithm is suitable for wormhole-routed networks.

• Journal of KIISE:Databases
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• v.37 no.6
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• pp.292-299
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• 2010

Recently, as flash memory is used as digital storage devices, necessity for digital forensics is growing in a flash memory area for digital evidence analysis. For this purpose, it is important to recover crashed files stored on flash memory efficiently. However, it is inefficient to apply the hard disk based file recovery techniques to flash memory, since hard disk and flash memory have different characteristics, especially flash memory being unable to in-place update. In this paper, we propose a flash-aware file recovery technique for digital forensics. First, we propose an efficient search technique to find all crashed files. This uses meta-data maintained by FTL(Flash Translation Layer) which is responsible for write operation in flash memory. Second, we advise an efficient recovery technique to recover a crashed file which uses data location information of the mapping table in FTL. Through diverse experiments, we show that our file recovery technique outperforms the hard disk based technique.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.11
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• pp.2052-2060
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• 2017

The SOLAS ship should carry at least 83 different types of equipment based on the SFI group codes and each of which consists of several to dozens of components. During ship operation, it is necessary to ensure the normal operation of such equipment, and remote maintenance is highly demanded for immediate repair in the event of a equipment fault. This study proposes to find suitable classification system and to derive database structure for remote maintenance of navigation and communication equipment. As a result of this study, the classification system of equipment should be layered into equipment type, model, and component, and main table in the database consists of FMEA, service history, case data through Q&A, Preventive Maintenance. A database was constructed for 140 navigation and communication equipment models and 750 components. In order to evaluate the practical effects, service engineer evaluated the usefulness using the cloud app.

• The KIPS Transactions:PartD
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• v.14D no.6
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• pp.623-632
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• 2007

GML is a markup language presented as exchange standard for geographic information by the OGC(Open GIS Consortium). In spatial network databases, researches for supporting GML(Geographic Markup Language) can be divided into the parsing, the storing and the retrieval of GML documents. Among them, the study on the storage of GML documents is essential for their efficient retrieval. However there is little research on the storing of GML documents whereas there have been a lot of researches on the storing of n documents. Because the storage schema designed for XML documents are not appropriate for geographic information, we, in this paper, propose three storage schema for efficiently storing GML documents including geographic information in order to solve the problem that the XML storage schema store duplicate data and need to search many tables for obtaining elements. In addition, we design and implement a low-level storage manager which can store GML documents using the proposed GML storage schema.

• Annual Conference on Human and Language Technology
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• 1999.10d
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• pp.60-75
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• 1999

품사 태깅은 자연 언어 처리의 가장 기본이 되는 부분으로 상위 자연 언어 처리 부분인 구문 분석, 의미 분석의 전처리로 사용되고, 독립된 응용으로 언어의 정보를 추출하거나 정보 검색 등의 응용에 사용되어 진다. 품사 태깅은 크게 통계에 기반한 방법, 규칙에 기반한 방법, 이 둘을 모두 이용하는 혼합형 방법 등으로 나누어 연구되고 있다. 포항공대 자연언어처리 연구실의 자연 언어 처리 엔진(SKOPE)의 품사 태깅 시스템 POSTAG는 미등록어 추정이 강화된 혼합형 품사 태깅 시스템이다 본 시스템은 형태소 분석기, 통계적 품사 태거, 에러 수정 규칙 후처리기로 구성되어 있다. 이들은 각각 단순히 직렬 연결되어 있는 것이 아니라 형태소 접속 테이블을 기준으로 분석 과정에서 형태소 접속 그래프를 생성하고 처리하면서 상호 밀접한 연관을 가진다. 그리고, 미등록어용 패턴사전에 의해 등록어와 동일한 방법으로 미등록어를 처리함으로써 효율적이고 강건한 품사 태깅을 한다. 한편, POSTAG에서 사용되는 태그세트와 한국전자통신연구원(ETRI)의 표준 태그세트 간에 양방향으로 태그세트 매핑을 함으로써, 표준 태그세트로 태깅된 코퍼스로부터 POSTAC를 위한 대용량 학습자료를 얻고 POSTAG에서 두 가지 태그세트로 품사 태깅 결과 출력이 가능하다. 본 시스템은 MATEC '99'에서 제공된 30000어절에 대하여 표준 태그세트로 출력한 결과 95%의 형태소단위 정확률을 보였으며, 태그세트 매핑을 제외한 POSTAG의 품사 태깅 결과 97%의 정확률을 보였다.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.34 no.12B
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• pp.1535-1541
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• 2009

In this paper, we suggest an efficient path searching algorithm that reduces the hop count when each node sends a data in ZigBee networks. As the hop count reduces, the network traffic is also reduces and leads to less energy consumption. This enables the sensor network live longer with limited node power. The proposed path searching algorithm consists of two sub-algorithms. One for upstream process and the other for downstream process. When a node selects its proper routing path, the node not only uses the information of the parent and child node, but it also uses the neighbor nodes for each node. In the simulation, we changed various network environment factors such as network parameters, number of nodes, and number of neighbor nodes and observed their performances. We compare the performance to the previous ZigBee Tree routing algorithm with separate two algorithms, the upstream and the downstream, and then compare the performance when all two algorithms are applied.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.11 no.5
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• pp.217-228
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• 2011

In centralize CDN systems, the content server selection is performed by service node for every user request, and the selected node is notified to the user. In this paper, we present distributed CDN architecture and algorithm in which the request from a user is delivered to the content source by a P2P algorithm utilizing DHT(distributed hash table) through the overlay network and the user selects one of the source nodes based on real-time user-centric criteria. For this purpose, we propose a modified Pastry algorithm for contents registration, search and selection, in addition to the distributed architecture. The proposed architecture has the advantages of load balancing, traffic balancing, scalability, fault-tolerance due to the self-configuration, self-healing attributes of distributed architecture. Various simulation shows the feasibility of the proposed architecture and algorithm, and the performance is compared and discussed for the variations of the proposed scheme.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.6
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• pp.923-930
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• 2002

This study aims at developing dialog system to improve the quality of life of the elderly with a dementia. The proposed system mainly consists of three modules including speech recognition, automatic search of the time-sorted dialog database, and agreeable responses with the recorded voices of caregivers. For the first step, the dialog that dementia patients often utter at a nursing home is first investigated. Next, the system is organized to recognize the utterances in order to meet their requests or demands. The system is then responded with recorded voices of professional caregivers. For evaluation of the system, the comparison study was carried out when the system was introduced or not, respectively. The occupational therapists then evaluated a male subjects reaction to the system by photographing his behaviors. The evaluation results showed that the dialog system was more responsive in catering to the needs of dementia patient than professional caregivers. Moreover, the proposed system led the patient to talk more than caregivers did in mutual communication.

• Journal of the Korea Society for Simulation
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• v.15 no.1
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• pp.59-67
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• 2006

In this paper, we propose an effective use of SuperSQL for efficient media publication that utilizes relational databases. SuperSQL is an enhanced SQL processing system that converts data stored in relational databases into a variety or applied formats, such as XML and HTML, as a result or query. In order to integrate various media generators in SuperSQL query processor, we discuss methods to prepare both for new media promptly and for efficient media publication processing system. This research makes two main contributions: (1) it is a study about methods to integrate media generators by combining common processes in SuperSQL query processor, and (2) it introduces the trinity data model, which divide the media generating processes into three aspects, which are value, structure and medium abstraction. We also show the good performance and feasibility of our system.

• Journal of the Institute of Electronics Engineers of Korea CI
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• v.42 no.3 s.303
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• pp.9-16
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• 2005

For designing the database more efficiently, normailzation can be enforced to minimize the degree of unnecessary data redundancy and contribute to enhance data integrity. However, deep normalization tends to provoke multiple way of schema join, which could then induces response time degradation. To mitigate this sort of side effect that the normalization could brought, a number of field studies we observed adopted the idea of denormalization. To measure whether denormalization contributes to response time improvement, we in this paper developed two different data models about customer service system, one with perfect normalization and the other with denormalization, and evaluated their query response time behaviors. Performance results show that normalization case consistently outperforms denormalization case in terms of response time. This study show that the idea of denormalization, quite rarely contributes to that sort of improvement due ironically to the unnecessary data redundancy.