• The Transactions of the Korea Information Processing Society
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• v.7 no.3
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• pp.766-775
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• 2000

Representing 3-D objects with LOD requires a set of appropriate meshes according to the detail requirements. We have developed a system for improved geometry model data transmission and management by having only the wavelet coefficienets of the model corresponding to the detail levels, instead of generation all the meshes through wavelet transformation, when generating multiresolution meshes.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2003.06a
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• pp.238-241
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• 2003

This paper presents a nonlinear least squares decision feedback equalizer Bilinear systems are attractive because of the ability to approximate a large class of nonlinear systems efficiently. The nonlinearity of channel is modeled using a bilinear system. The algorithms are derived by using the QR decomposition for minimization covariance matrix of prediction error by applying Givens rotation to the bilinear model. Result of computer simulation experiments that compare the performance of the bilinear DFE to two other DFE's in eliminating the intersymbol interference caused by a nonlinear channel are presented In the paper.

• Proceedings of the Korea Institute of Convergence Signal Processing
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• 2000.08a
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• pp.89-92
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• 2000

필터뱅크를 기반으로 하는 이산 웨이브렛 멀티톤(DWMT) 데이터 전송 시스템은 전송 채널의 영향으로 발생하는 심벌간 및 부채널간의 간섭 잡음에 민감하다. 본 논문에서 제안한 시간 영역 등화기(TEQ)는 전송 채널 응답의 길이를 단축시키는 TEQ-S와 전송 채널의 주파수 특성을 향상시키는 TEQ-C등 2단계로 이루어져 있다. 제안한 시간영역 등화기(TEQ)를 DWMT 데이터 전송 시스템에 적용하면 많은 간섭 성분을 감소시킬 수 있어 하드웨어적으로 보다 간단한 FEQ로도 잔여 간섭 잡음을 효과적으로 제거할 수 있다.

• Proceedings of the Korea Information Processing Society Conference
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• 2009.04a
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• pp.1264-1266
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• 2009

We introduce a location-based routing model applied for grid backbone nodes in wireless mesh network. The number of paths with nearest distance between two nodes is calculated and used as key parameter to execute routing algorithm. Node will increase the transmission range that makes a trade off with data rate to reach its neighbors when node itself is isolated. The routing model is lightweight and oriented thanks to the simple but efficient routing algorithm.

• Proceedings of the Korea Information Processing Society Conference
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• 2008.11a
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• pp.1211-1214
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• 2008

최근 Path-diversity에 근거한 통신 방식은 다양한 P2P streaming 어플리케이션에 대역폭 고갈 현상을 해결하는 쪽으로 연구가 진행 중이다. 이 논문에서는 네트워크의 대역폭 확보와 효과적인 데이터 전송을 위해서 다소 직관적인 방법인 다중시간이론을 소개하고, 이를 P2P 네트워크에 적용할 수 있는 방법을 제시한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.4
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• pp.1931-1953
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• 2017

The reverse skyline query plays an important role in information searching applications. This paper deals with continuous reverse skyline queries in sensor networks, which retrieves reverse skylines as well as the set of nodes that reported them for continuous sampling epochs. Designing an energy-efficient approach to answer continuous reverse skyline queries is non-trivial because the reverse skyline query is not decomposable and a huge number of unqualified nodes need to report their sensor readings. In this paper, we develop a new algorithm that avoids transmission of updates from nodes that cannot influence the reverse skyline. We propose a data mapping scheme to estimate sensor readings and determine their dominance relationships without having to know the true values. We also theoretically analyze the properties for reverse skyline computation, and propose efficient pruning techniques while guaranteeing the correctness of the answer. An extensive experimental evaluation demonstrates the efficiency of our approach.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2004.04a
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• pp.375-382
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• 2004

Lately, 3D GIS begins to be widely used in many application fields. In this research, we proposed a survey and analysis result of research trends for 3D GIS technologies-acquisition of 3D spatial data, 3D features structuring, 3D visualization, data query, and transmission etc. The result is expected to give the helpful information for constructing research road-map on development of 3D GIS technologies.

• The Transactions of the Korea Information Processing Society
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• v.7 no.6
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• pp.1766-1777
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• 2000

In multimedia new service on the internet, there are problems such as server overload, network congestion and initial latency. To overcome these problems, we propose a proxy push-caching scheme that stores a portion of continuous media stream or entire stream, and a transmission scheme of NOD continuous media, RTP-RR and RTP-nR to exploit push-caching scheme. With the proposed push-caching scheme, NOD server pushes fixed portion of stream to a proxy when new data is generated, and the cached size of each stream changes dynamically according to the caching utility value of each stream. As a result, the initial latency of client side could be reduced and the amount of data transmitted fro ma proxy server to client could be increased. Moreover, we estimate a caching utility value of each stream using correlation between disk space occupied by the stream and the amount of data stream requested by client. And we applied the caching utility value ot replacement policies. The performance of the proxy push-caching and continuous media transmission schemes proposed were compared with other schemes using simulations. In the simulation, these schemes show better results than other schemes in terms of BHR (Byte Hit Rate), initial latency, the number of replacement and packet loss rate.

• Journal of Multimedia Information System
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• v.5 no.1
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• pp.27-34
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• 2018

In recent years, with the blooming of Internet of Things (IoT) and Cloud Computing (CC), researchers have begun to discover new methods of technological support in all areas (e.g. health, transport, education, etc.). In this paper, in order to achieve a type of network that will provide more intelligent media-data transfer new technologies were studied. Additionally, we have been studied the use of various open source tools, such as CC analyzers and simulators. These tools are useful for studying the collection, the storage, the management, the processing, and the analysis of large volumes of data. The simulation platform which have been used for our research is CloudSim, which runs on Eclipse software. Thus, after measuring the network performance with CloudSim, we also use the Cooja emulator of the Contiki OS, with the aim to confirm and access more metrics and options. More specifically, we have implemented a network topology from a small section of the script of CloudSim with Cooja, so that we can test a single network segment. The results of our experimental procedure show that there are not duplicated packets received during the procedure. This research could be a start point for better and more efficient media data transmission.

• International Journal of Internet, Broadcasting and Communication
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• v.15 no.4
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• pp.261-269
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• 2023

We propose to design a Holochain-based security and privacy protection system for resource-constrained IoT healthcare systems. Through analysis and performance evaluation, the proposed system confirmed that these characteristics operate effectively in the IoT healthcare environment. The system proposed in this paper consists of four main layers aimed at secure collection, transmission, storage, and processing of important medical data in IoT healthcare environments. The first PERCEPTION layer consists of various IoT devices, such as wearable devices, sensors, and other medical devices. These devices collect patient health data and pass it on to the network layer. The second network connectivity layer assigns an IP address to the collected data and ensures that the data is transmitted reliably over the network. Transmission takes place via standardized protocols, which ensures data reliability and availability. The third distributed cloud layer is a distributed data storage based on Holochain that stores important medical information collected from resource-limited IoT devices. This layer manages data integrity and access control, and allows users to share data securely. Finally, the fourth application layer provides useful information and services to end users, patients and healthcare professionals. The structuring and presentation of data and interaction between applications are managed at this layer. This structure aims to provide security, privacy, and resource efficiency suitable for IoT healthcare systems, in contrast to traditional centralized or blockchain-based systems. We design and propose a Holochain-based security and privacy protection system through a better IoT healthcare system.