• The Journal of Korean Institute of Communications and Information Sciences
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• v.39A no.6
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• pp.303-309
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• 2014

Chaos communication system can improve a system security due to characteristics of non-periodic, non-predictability, broadband signal and easy implementation. Also, chaos signal is sensitive to initial conditions of chaos map. By these reasons, security of chaos communication system is superior to digital communication system. BER performance of COOK modulation system is better than other chaos modulation systems, even if COOK modulation system uses an asynchronous receiver. However, security and safety of COOK modulated signal are worse than other chaos modulation systems, because information bits can be easily predicted from COOK modulated signal. In this paper, for security improvement of COOK modulated signal, we propose a novel Scrambling COOK modulation system by applying the scrambling method. Conventional COOK modulated signal can be predicted, because chaos signal is generated when data is only 1. However, proposed system cannot be predicted, because chaos signal is generated when data is 0 or 1. Therefore, security and safety of transmitted signal in scrambling COOK modulation system is superior to conventional COOK modulation system.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.33 no.9B
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• pp.832-844
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• 2008

Distributed localization algorithms are necessary for large-scale wireless sensor network applications. In this paper, we introduce an efficient node distribution based localization algorithm that emphasizes simple refinement and low system load for low-cost and low-rate wireless sensors. Each node adaptively chooses neighbor nodes for sensors, update its position estimate by minimizing a local cost function and then passes this update to the neighbor nodes. The update process considers a distribution of nodes for large-scale networks which have same density in a unit area for optimizing the system performance. Neighbor nodes are selected within a range which provides the smallest received signal strength error based on the real experiments. MATLAB simulation showed that the proposed algorithm is more accurate than trilateration and les complex than multidimensional scaling. The implementation on MicaZ using TinyOS-2.x confirmed the practicality of the proposed algorithm.

• Journal of the Korean Society for Library and Information Science
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• v.49 no.3
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• pp.333-349
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• 2015

This study examined the application of the FRBR model to newspapers and news articles. In order to meet the purpose that was mentioned above, we analyzed data items based on the level of newspapers and articles and discussed how the FRBR model may be applied. In terms of the level of a newspaper, each of newspapers, morning/evening paper, issue and edition are regarded as an individual work, and the relationship among them are considered to be the 'whole-part relationship'. Each article on the level of article basis was considered to be a work and was in a relationship of 'whole-part relationship' with the edition of each level of newspapers. Newspaper articles can be represented as texts, photographs, graphics, and tables, etc., and regarded as an individual work. Each work can be a part of the article on a newspaper or can be an independent article itself. Moreover, a uniform heading of each boxed article and running story is included in the work of each article and is forming a 'whole-part relationship'. Because of the changes of the newspaper name, the uniform title of each name regarded as a single binding. It is called the superwork and it is forming 'whole-part relationship' with each name.

• The Journal of the Korea institute of electronic communication sciences
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• v.14 no.3
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• pp.537-546
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• 2019

In this paper, a system that integrates a home concentrate unit(HCU) in a smart electricity meter to collects water, gas, hot water, and heating usage required for AMI has been proposed. The collected data could be transmitted to the in house display(IHD) and server to provide a more economical AMI system. The developed system is less expensive in the network configuration than the existing system, which could reduce the operating cost, and be easy to install. By applying the developed system, the usage of electricity, water, gas, hot water and heating could be measured and these make it easier to apply AMI system. The main contents of the development are the smart electricity meter and embedding of HCU into the smart electricity meter, and transferring these data to IHD and server to structure the AMI system. The each developed unit has been networked to structure the AMI system to perform the actual meter reading operation and show the result.

• Journal of the Korea Society for Simulation
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• v.30 no.1
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• pp.139-152
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• 2021

Simulations enable virtually experiencing rare events as well as analytically analyzing such events. Defense modeling and simulation research and develops the virtual and the constructive simulations to support these utilizations. These virtual and constructive(VC) simulations can interoperate to simultaneously virtual combat experience as well as evaluations on tactics and intelligence of combat entities. Moreover, recently, for artificial intelligence researches, it is necessary to retrieve human behavior data to proceed the imitation learning and the inverse reinforcement learning. The presented work illustrates a case study of VC interoperations in the aircombat scenario, and the work analyze the collected human behavior data from the VC interoperations. Through this case study, we discuss how to build the VC simulation in the aircombat area and how to utilize the collected human behavior data.

• The Journal of the Acoustical Society of Korea
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• v.40 no.2
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• pp.148-154
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• 2021

Text-Independent speaker verification needs to extract text-independent speaker embedding to improve generalization performance. However, deep neural networks that depend on training data have the potential to overfit text information instead of learning the speaker information when repeatedly learning from the identical time series. In this paper, to prevent the overfitting, we propose a segment unit shuffling layer that divides and rearranges the input layer or a hidden layer along the time axis, thus mixes the time series information. Since the segment unit shuffling layer can be applied not only to the input layer but also to the hidden layers, it can be used as generalization technique in the hidden layer, which is known to be effective compared to the generalization technique in the input layer, and can be applied simultaneously with data augmentation. In addition, the degree of distortion can be adjusted by adjusting the unit size of the segment. We observe that the performance of text-independent speaker verification is improved compared to the baseline when the proposed segment unit shuffling layer is applied.

• Journal of Digital Convergence
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• v.12 no.9
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• pp.201-207
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• 2014

In the cloud environment, the company needs data integration and analysis to make decision and policy. If new system is added to this environment, a lot of time and cost is needed due to disparate properties among systems when data is integrated. Therefore, in this paper, we propose a DBaaS hub system for multi-database service. The DBaaS may require a different database and need data integration for relevant service. Using the ontology, we propose a metadata query to resolve the interoperability issues between data of DBaaS. The meta-query is not a query to access the real data, but the query for the upper level. This method provides data integration by accessing the data with the converted query through an ontology when we access the actual database.We also constructs a document-oriented database system using the metadata.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.9
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• pp.1-8
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• 2017

The purpose of this study is to propose a cache structure for processing large-volume building information modeling (BIM) geometry data,whereit is difficult to allocate physical memory. As the number of BIM orders has increased in the public sector, it is becoming more common to visualize and calculate large-volume BIM geometry data. Design and review collaboration can require a lot of time to download large-volume BIM data through the network. If the BIM data exceeds the physical free-memory limit, visualization and geometry computation cannot be possible. In order to utilize large amounts of BIM data on insufficient physical memory or a low-bandwidth network, it is advantageous to cache only the data necessary for BIM geometry rendering and calculation time. Thisstudy proposes acache structure for efficiently rendering and calculating large-volume BIM geometry data where it is difficult to allocate enough physical memory.

• Proceedings of the Korea Contents Association Conference
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• 2009.05a
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• pp.3-7
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• 2009

Data centric storages for sensor networks have been proposed to efficiently process multi-dimensional range queries as well as exact matches. Usually, a sensor network does not process only one type of the query but supports various types of queries such as range queries, exact matches and skyline queries. Therefore, a sensor network based on a data centric storage for range queries and exact matches should process skyline queries efficiently. However, existing algorithms for skyline queries have not considered the features of data centric storages. Some of the data centric storages store similar data in sensor nodes that are placed on geographically similar locations. Consequently, all data are ordered in a sensor network. In this paper, we propose a new skyline query processing algorithm that exploits the above features of data centric storages.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.10
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• pp.2292-2302
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• 1997

In this paper, we propose a wireless MAC protocol named APRMA, which is capable of supporting the ABR type data service and maximizing channel utilization. In PRMA protocol, data terminals with random data packets cannot reserve slot. That is, slot reservation is applicable to the time constraint voice packet exclusively. But the reservation scheme has to be performed for loss sensitive data packet, and so data packets can get their quality of service. Therefore, in wireless MAC, reservation technique has to be used for both voice and data services. But in service aspects, if a fixed bandwidth is allocated to data terminals, time constraint voice packets may have a low efficiency. So in this study, the terminal which wants to request for ABR tyupe service, acquires a minimum bandwidth from system for thefirst time. If the system has extra available bandwidth, ABR terminals would acquire additional bandwidth slot by slot. As a result, APRMA protocol cansupporty the data service with loss sensitivity and maintain their channel utilization high. Also high priority services like voice can be satisfied with their QoS by APRMA.