• Journal of Computing Science and Engineering
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• v.2 no.4
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• pp.394-411
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• 2008

The data in automation and control systems can be achieved not only from different field devices but also from different OPC (OLE for Process Control) servers. However, current OPC clients can only read and decode the simple data from OPC servers. They will have some problems to acquire structured data and exchange the structured data. In addition to the large network control systems, the OPC clients can read, write, and subscribe to thousands of data points from/to OPC servers. Due to that, the most important factor for building a high performance and scalable industrial control system is the ability to transfer the process data between server and client in the most efficient and fastest way. In order to solve these problems, we propose a means to implement the OPC DA (Data Access) server supporting the OPC complex data, so that the OPC DA clients are able to read and decode any type of data from OPC servers. We also propose a method for caching the process data in large industrial control systems to overcome the limitation of performance of the pure OPC DA system. The performance analysis and discussion indicate that the proposed system has an acceptable performance and is feasible in order for applying to real-time industrial systems today.

• Journal of KIISE:Databases
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• v.35 no.6
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• pp.495-504
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• 2008

Recently, there has been much work on supporting keyword search not only for text documents, but a]so for structured data such as relational data, XML data, and RDF data. In this paper, we propose an efficient keyword search method for RDF data. The proposed method first groups related nodes and edges in RDF data graphs to reduce data sizes for efficient keyword search and to allow relevant information to be returned together in the query answers. The proposed method also utilizes the semantics in RDF data to measure the relevancy of nodes and edges with respect to keywords for search result ranking. The experimental results based on real RDF data show that the proposed method reduces RDF data about in half and is at most 5 times faster than the previous methods.

• Proceedings of the Korean Information Science Society Conference
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• 2006.06a
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• pp.250-252
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• 2006

Web technologies are gaining increased importance in automation and control systems. However, the choice of Web technologies depends on the use cases in the application environment. In industrial systems, the data can be got not only from many different field systems and devices but also from different OPC (OLE for Process Control) Servers. Current OPC Client might be able to read simple data from OPC Server, but there are some problems to get structured data and to exchange structured information between collaborating applications. Therefore, OPC Foundation has defined interfaces to OPC XML-DA (OPC XML Data Access) and OPC Complex Data that aim to solve those problems. The OPC XML-DA can facilitate the exchange of plant data across the internet, and upwards into the enterprise domain. In addition, the OPC Complex Data will extend the OPC DA specification to allow the OPC Client to read and decode any type of data from measurement and control systems on the plant floor. This paper will describe the concept of OPC XML-DA and OPC Complex Data. And then it proposes a mechanism to implement the OPC Complex Data into OPC XML-DA Server. Additionally, the paper also discusses the security aspects.

• Journal of KIISE
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• v.43 no.2
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• pp.135-142
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• 2016

Visual analysis of spatiotemporal data has focused on a variety of techniques for analyzing and exploring the data. The goal of these techniques is to explore the spatiotemporal data using time information, discover patterns in the data, and analyze spatiotemporal data. The overall trend flow patterns help users analyze geo-referenced temporal events. However, it is difficult to extract and visualize overall trend flow patterns using data that has no trajectory information for movements. In order to visualize overall trend flow patterns, in this paper, we estimate continuous distributions of discrete events over time using KDE, and we extract vector fields from the continuous distributions using the gravity model. We then apply our technique on twitter data to validate techniques.

• KIISE Transactions on Computing Practices
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• v.21 no.1
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• pp.58-63
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• 2015

In this work, we present a novel fountain code-based hybrid P2P storage system that combines cloud storage with P2P storage. The proposed hybrid storage system minimizes data transmission time while guaranteeing high data retrieval and data privacy. In order to guarantee data privacy and storage efficiency, the user transmits encoded data after performing fountain code-based encoding. Also, the proposed algorithm guarantees the user's data retrieval by storing the data while considering each peer's survival probability. The simulation results show that the proposed algorithm enables fast completion of the upload transmission while satisfying the required data retrieval and supporting the privacy of user data under the system parameters.

• Journal of KIISE:Databases
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• v.33 no.1
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• pp.32-41
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• 2006

In data-centric networks, various data items, such as temperature, humidity, etc. are sensed and stored in sensor nodes. As these attributes are mostly scalar values and inter-related, multi-dimensional range queries are useful. To process multi-dimensional range queries efficiently in data-centric storage, data addressing is essential. The Previous work focused on efficient query processing without considering overall network lifetime. To prolong network lifetime and support multi-dimensional range queries, we propose a dynamic data distribution method for multi-dimensional data, where data space is divided into equal-sized regions and linearized by using Hilbert space filling curve.

• Journal of the Korea Society of Computer and Information
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• v.14 no.6
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• pp.125-134
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• 2009

A biological data acquisition based on web has emerged as a powerful tool for allowing scientists to interactively view entries form different databases, and to navigate from one database to another molecular-biology database links. In this paper, the biological conceptual model is constructed hybrid biological data model to represent interesting entities in the data sources to applying navigation rule property for each biological data source based on four biological data integrating layers to control biological data. When some user's requests for application service are occurred, we can get the data from database and data source via web service. In this paper, we propose a query processing model and execution structure based on integrating data layers that can search information on biological data sources.

• Proceedings of the Korean Information Science Society Conference
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• 2005.11a
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• pp.271-273
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• 2005

In wireless UDP data transfers, the handoff is one of the most breaking down things. To polycast multimedia data to several clients a sewer may connect clients by UDP networks. Mostly, video data must be compressed based on difference between before and next packets. Thus, the packet losses on the video stream may cause the recomposing of video data to be corrupt. This proposal provides simply retransmitting of lost packets according to a sequence and buffering packets in a given order.

• Proceedings of the Korean Information Science Society Conference
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• 1998.10a
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• pp.577-579
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• 1998

지상파, 케이블, 위성 등의 기존 방송망을 이용하여, 사용자의 부합하는 데이터를 전송하는 데이터 방송 기법에 대한 연구와 표준화 작업이 활발하게 진행 중이다. 우리나라의 경우, 무궁화 위성을 이용한 부가 데이터 방송을 구현하고자 연구중이다. 데이터 방송시 데이터 전송 기법에는 데이터 스트리인(data streaming). 데이터 파이핑(data piping),데이터 캐루셀(data carousel)등이 제안되고 있다. 본 논문에서는 표준화 단체인 DVB에서 정의하고 있는 데이터 전송 기법에 대한 소개와, 함께, 데이터 캐루셀을 이용한 데이터 방송 구현에 필요한 소프트웨어 설계와 실제 구현에 관한 내용을 담고 있다.

• Journal of Computing Science and Engineering
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• v.11 no.2
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• pp.69-77
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• 2017

Recent GPUs have adopted cache memory to benefit general-purpose GPU (GPGPU) programs. However, unlike CPU programs, GPGPU programs typically have considerably less temporal/spatial locality. Moreover, the L1 data cache is used by many threads that access a data size typically considerably larger than the L1 cache, making it critical to bypass L1 data cache intelligently to enhance GPU cache performance. In this paper, we examine GPU cache access behavior and propose a simple hardware-based GPU cache bypassing method that can be applied to GPU applications without recompiling programs. Moreover, we introduce a hybrid method that integrates static profiling information and hardware-based bypassing to further enhance performance. Our experimental results reveal that hardware-based cache bypassing can boost performance for most benchmarks, and the hybrid method can achieve performance comparable to state-of-the-art compiler-based bypassing with considerably less profiling cost.