• 한국IT서비스학회지
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• 제8권1호
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• pp.179-192
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• 2009

In wireless environments, it is very effective to introduce a data broadcast system for providing a number of clients with mobile data services. In particular, an efficient broadcast scheduling and a caching strategy are very important for performance of data broadcast systems in wireless environments which have such inherent restrictions as low bandwidth, frequent disconnections, and short battery life. In this paper, we present a data broadcast scheduling strategy using bit vectors to cope with dynamic request patterns of clients. In addition, we also propose an efficient caching strategy, 2FWT, that takes characteristics of the broadcast scheduling strategy into account. Finally, we evaluate performance of the data broadcast system. According to the results, the proposed system generally shows better performance than others.

• 한국인터넷방송통신학회논문지
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• 제14권5호
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• pp.173-178
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• 2014

스마트폰과 초고속 네트워크에 연결된 스마트폰과 같은 클라이언트는 다양한 위치기반 서비스를 언제 어디서나 사용할 수 있게 해주고 있다. 이런 환경에서 무선 데이터 방송 시스템은 대규모의 클라이언트들의 다양한 데이터 요구를 효과적으로 처리할 수 있게 한다. 효율적인 무선 데이터 방송 시스템을 구축하기 위해 다양한 데이터 스케줄링 기법과 인덱싱 기법이 개발되고 있으나 이러한 기법들을 신속히 평가하기 위한 시뮬레이션 프레임워크의 개발은 보고된 것이 없다. 본 논문에서는 시뮬레이션 기반의 무선 데이터 방송 시스템 성능 평가를 위한 시뮬레이션 프레임워크를 설계 및 구현한다. 개발된 프레임워크는 무선 데이터 방송 시스템의 성능을 빠르게 평가할 수 있으며 다양한 데이터 스케줄링 기법과 인덱싱 기법을 적용할 수 있는 확장성을 가진다.

• International journal of advanced smart convergence
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• 제9권2호
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• pp.164-172
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• 2020

The interest and importance of the convergence services for healthcare expand more and more as the average life expectancy increases. Convergence of ICT and healthcare technology unfold efficient and quick health services. Recently, healthcare services provide to clients with apps over web. On-demand wireless data broadcast supports any number of clients to access their desired data items dynamically by responding the needs for data items from the clients. In this paper, we propose an on-demand system to broadcast FHIR bundles for efficient healthcare services. We use time-parameterized replacing policy for renewing the bundle items on the wireless broadcast channel. The policy lets the on-demand broadcasting dynamic by controlling the time duration for the bundles to reside over the wireless channel. With simulation studies using an implemented testbed, we evaluate the performances of the proposed system in access time and tuning time. For evaluation, we compare the time-parameterized replacing policy of the proposed system with regular-number replacing policy. The proposed time-parameterized replacing policy shows shorter access time than the regular-number replacing policy because the policy responds more actively and dynamically to the change of the needs of the clients for FHIR bundles.

• International Journal of Advanced Culture Technology
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• 제6권4호
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• pp.65-70
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• 2018

Wireless data broadcasting system that can support any number of clients is the effective alternative for the challenge of scalability in ubiquitous computing in IoT environment. In the system, it is important to evaluate quickly the performance parameter, the access time that means how quickly the client access desired data items. In this paper, we derive the mathematical model for the access time in the wireless data broadcast system adopting two-tier indexing scheme. The derived model enables to evaluate the access time without the complicated simulation. In order to evaluate the model, we compare the access time by the model with the access time by the simulation.

• International journal of advanced smart convergence
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• 제7권4호
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• pp.10-18
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• 2018

For the information services supporting requests of data items from a great number of mobile clients, wireless data broadcasting is an effective way because it can accommodate any number of clients. In the wireless data broadcasting, various air indexing schemes and data scheduling schemes have been developed in order to enable the clients to access their desired data items efficiently. The broadcasting system needs a method to simulate newly designed air indexing and scheduling schemes of the system, and to evaluate the performance parameters of the schemes. In this paper, we design an expandable and efficient simulation framework for the wireless data broadcasting based on the partition of data ID space. The framework can adopt regular and irregular space partition and evaluate various performance parameters of the broadcasting system. We implement a testbed of the broadcasting system using the framework, that adopts IIP, GDI and EXP as its air indexing schemes. We simulate the system using the testbed and evaluate the performance parameters of the system. Thus, we show the efficiency and expandability of the designed and implemented framework.

• International Journal of Internet, Broadcasting and Communication
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• 제15권2호
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• pp.22-30
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• 2023

The portable mobile devices with high performance and high speed 5G network activate and explode the demands for ubiquitous information services that remove the limitations of time for the communication and places to request for the information. NN (Nearest Neighbor) search is one of the most important types of queries to be processed efficiently in the information services. Various indexes have been proposed to support efficient NN search in the wireless broadcast system. The indexes adopting Hilbert curve, grid partition or Voronoi diagram enable the clients to search for NN quickly in the wireless broadcast channel. It is necessary that an efficient means to evaluate the performances of various indexes. In this paper, we propose an open framework that can adopt a variety of indexing schemes and evaluate and compare the performances of them. The proposed framework is organized with open and flexible structure that can adopt hybrid indexing schemes extensible to Voronoi diagram as well as simple indexing schemes. With the implemented framework, we demonstrate the efficiency and scalability and flexibility of the proposed framework by evaluating various indexing schemes for NN query.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2008년도 한국컴퓨터종합학술대회논문집 Vol.35 No.1 (D)
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• pp.291-296
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• 2008

Wireless network technologies are becoming more widely used in industrial environment. The industrial communication system requires a real-time delivery of messages. The sensors periodically senses the physical environment and wants to deliver the data in real-time to the sink. This paper proposes a real-time protocol for periodic messages on wireless sensor and actor networks to be used in industrial communications. The proposed protocol delivers the data message using the shortest path from the source and the nearest actor. The protocol considers the energy consumption by reducing the number of broadcast messages during flooding. We have evaluated the performance of the proposed protocol using QualNet simulator. The simulation results show that the data messages have been delivered in real-time and the number of broadcast messages is reduced from 90% to 35% compared the existing protocols.

• 대한전자공학회논문지TC
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• 제46권5호
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• pp.56-63
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• 2009

IEEE 802.11 표준은 무선랜, 애드 혹 망 및 차량간 통신 망 등 무선 데이터 망에 광범위하게 이용되고 있다. 이에 따라 망 성능 최적화 및 효과적인 망 자원 관리 기법의 개발을 위해 IEEE 802.11의 성능 분석이 광범위하게 이루어져 왔으나 대부분의 성능 분석 연구들은 데이터 평면에서 유니캐스트 전송 기법의 성능에 관한 것들이었다. 그러나 무선 데이터 망에서는 망 형상 관리, 노드 사이의 경로 관리 및 데이터 전송 방법으로 IEEE 802.11 브로드캐스트 기법을 이용하고 있다. 따라서 IEEE 802.11 브로드캐스트 기법의 성능에 대한 정확한 이해는 무선 데이터 망 설계를 위해 매우 중요하다. 이에 따라 본 논문에서는 노드의 전송 범위, 데이터 전송율, 최소 경합 윈도우의 크기와 같은 IEEE 802.11 시스템 파라미터뿐만 아니라 노드의 수, 망의 부하, 전파 전송 환경과 같은 망 운용 환경을 모두 고려하여 IEEE 802.11 브로드캐스트 기법의 성능을 송신 노드와의 거리에 따른 브로드캐스트 프레임 수신 확률 측면에서 분석한다. 제안된 분석 프레임은 망 환경과 관련된 모든 파라미터들을 고려하기 때문에 동적인 무선 데이터 망 환경을 위한 적응성 있는 제어 기법 개발에 이용될 것으로 기대된다.

• 정보처리학회논문지C
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• 제12C권2호
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• pp.243-250
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• 2005

낮은 대역폭이나 잦은 단절 같은 무선 통신의 근본적인 제약으로 인한 방송 시스템의 성능 저하를 완화할 수 있는 방법 중의 하나는 클라이언트에 캐시를 도입하는 것이다. 본 논문에서는 비트 벡터를 이용한 혼합 데이터 방송 시스템에서 클라이언트가 최근에 요구하는 데이터를 효과적으로 방송할 수 있도록 pull 기반 방송전략을 제안한다. 그리고, 방송 알고리즘의 특성을 고려한 효율적인 캐싱 전략을 제안하고 시스템의 성능을 평가한다. 평가 결과에 따르면, 제안한 전략들을 수용한 시스템이 응답 시간 측면에서 전반적으로 좋은 성능을 보여준다.

• 한국방송∙미디어공학회:학술대회논문집
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• 한국방송공학회 2009년도 IWAIT
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• pp.673-677
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• 2009

In this paper, a transmitting process of a sequence of holograms describing 3D moving objects over the communicating wireless-network system is presented. A sequence of holograms involves holograms is transformed into a bit stream data, and then it is transmitted over the wireless LAN and Bluetooth. It is shown that applying this technique, holographic data of 3D moving object is transmitted in high quality and a relatively good reconstruction of holographic images is performed.