• KSII Transactions on Internet and Information Systems (TIIS)
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• 제12권4호
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• pp.1618-1637
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• 2018

By means of compressive sensing (CS) technique, this paper considers the collection of sensor data with spatiotemporal correlations in wireless sensor networks (WSNs). In energy-constrained WSNs, one-dimensional CS methods need a lot of data transmissions since they are less applicable in fully exploiting the spatiotemporal correlations, while the Kronecker CS (KCS) methods suffer performance degradations when the signal dimension increases. In this paper, an appropriate sensing matrix as well as an efficient sensing method is proposed to further reduce the data transmissions without the loss of the recovery performance. Different matrices for the temporal signal of each sensor node are separately designed. The corresponding energy-efficient data gathering method is presented, which only transmitting a subset of sensor readings to recover data of the entire WSN. Theoretical analysis indicates that the sensing structure could have the relatively small mutual coherence according to the selection of matrix. Compared with the existing spatiotemporal CS (CS-ST) method, the simulation results show that the proposed efficient measurement method could reduce data transmissions by about 25% with the similar recovery performance. In addition, compared with the conventional KCS method, for 95% successful recovery, the proposed sensing structure could improve the recovery performance by about 20%.

• 디지털산업정보학회논문지
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• 제5권3호
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• pp.107-115
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• 2009

Traditionally, simulation method is used to test and evaluate the performance of communication protocol or functional elements for mobile communication service. In this paper, wireless network simulator is implemented using the C++ object-oriented programming language. This simulator can simulate wireless data services, like as ad-hoc networks, by considering the user's mobility. In this paper, the simulator includes network traffic model to reflect wireless data service and traffic source model to represent a user's mobility similar to real service environment and traffic characteristics can be reflected on the simulation, and also more accurate simulation results can be got through that. In addition, by using object-oriented techniques, new service feature or environment can be easily added or changed so that the developed mobile communication simulator can reflect the real service environment all the time. This simulator can be used in adjusting the characteristics of wireless data hosts following the mobility of the user, and also can be used in building new wireless ad-hoc network routing protocols.

• 반도체디스플레이기술학회지
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• 제3권4호
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• pp.13-17
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• 2004

As the usage of wireless LAN becomes common in working environment, the number of database systems that support both wired and wireless users increases rapidly. The characteristics of wireless LAN that its speed is slow relatively comparing to wired network and the users in its environment connects to different communication points as they moves creates another challenge to be resolved in database systems. In the environment of hybrid communication systems, wired and wireless for voluminous data amount and a number of users, the two layer architecture of the conventional client-server database systems has limitation in the system performance. This is due to that server is the only point of data service in client-server database systems. In this paper, we discuss a new extended database system architecture that data services are distributed among servers and clients based on user database access patterns in order to improve system performance. We analyze the expected system performance by using simulation technique and prove the practical utilization of the system by demonstrating experimental results.

• 한국통신학회논문지
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• 제24권10A호
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• pp.1501-1506
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• 1999

DSR(Dedicated Short Communications)는 ITS 서비스를 지원하기 위한 이동 통신 방식으로서 교통 정보 서비스에 적합하다. 그러나 ITS에서 일반적인 데이터 서비스를 지원할 경우에는 기존의WAC (Wide Area wireless Communications) 방식을 고려할 필요가 있다. 특히 이동통신 망에서의 무선 인터넷 서비스 지원을 위한 활발한 연구를 고려할 때, ITS에서의 인터넷 서비스 지원은 고려할 가치가 있다. DSRC의 무선 구간 에러 및 흐름 제어를 담당하는 LLC(Logical Link Control) 프로토콜은 교통 정보 서비스를 지원하기에는 적합하나, 영상, 지리정보, 인터넷과 같은 서비스에는 효율적이지 못하다. 그 이유는 서비스에 따라 데이터의 트래픽 특성이 달라지기 때문이다. 따라서 본 논문에서는 DSRC에서 교통 정보 서비스뿐만 아니라 인터넷 웹 서비스까지 효율적으로 지원할 수 있는 LLC 프로토콜을 제안하고 그 성능을 분석한다. 성능 분석의 결과, 제안된 알고리즘이 교통 정보 서비스에 대해서는 일본과 유럽에서 제안된 DSRC LLC 프로토콜과 동일한 성능을, 인터넷 웹 서비스에 대해서는 우월한 성능을 나타냄을 확인하였다.

• 한국정보통신학회:학술대회논문집
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• 한국정보통신학회 2012년도 춘계학술대회
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• pp.232-234
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• 2012

NMEA2000 표준은 선박 내부 센서 및 장비들 간의 실시간 통신을 위해 개발되었다. 본 논문에서는 NMEA2000 네트워크 프로토콜을 분석하여 데이터를 무선으로 서비스하기 위한 게이트웨이 개발에 대해 기술한다. 확장성을 높이기 위해 개발된 게이트웨이는 NMEA2000 네트워크에 직접적으로 참여하지 않고 무선 장비와 NMEA2000 사이에 단순히 데이터를 중계하는 방식을 사용하였다.

• 한국멀티미디어학회논문지
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• 제20권9호
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• pp.1519-1526
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• 2017

The existing DSRC(Dedicated Short Range Communication) scheme has a limitation in providing various services through short-range wireless communication. Therefore, it is necessary to develop an intelligent WAVE/DSRC hybrid wireless platform that can improve data transmission speed and extend the effective communication range. This paper introduces WAVE/DSRC integrated platform technology using WAVE(Wireless Access in Vehicle Environments) to overcome the disadvantages of DSRC. First, the desinged software configuration of the WAVE/DSRC integrated platform is described. Then each task operation scheme and WAVE software design are described. By applying the WAVE/DSRC integrated platform, we can compensate the shortcomings of DSRC. It can provide more accurate and reliable services.

• Smart Structures and Systems
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• 제5권2호
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• pp.119-137
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• 2009

Smart sensors densely distributed over structures can use their computational and wireless communication capabilities to provide rich information for structural health monitoring (SHM). Though smart sensor technology has seen substantial advances during recent years, implementation of smart sensors on full-scale structures has been limited. Hardware resources available on smart sensors restrict data acquisition capabilities; intrinsic to these wireless systems are packet loss, data synchronization errors, and relatively slow communication speeds. This paper addresses these issues under the hardware limitation by developing corresponding middleware services. The reliable communication service requires only a few acknowledgement packets to compensate for packet loss. The synchronized sensing service employs a resampling approach leaving the need for strict control of sensing timing. The data aggregation service makes use of application specific knowledge and distributed computing to suppress data transfer requirements. These middleware services are implemented on the Imote2 smart sensor platform, and their efficacy demonstrated experimentally.

• 한국정보처리학회논문지
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• 제3권3호
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• pp.493-500
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• 1996

무선 메세지 전송, 무선 데이타 베이스, 이동 컴퓨팅 등에 대한 관심이 증대됨 에 따라 이동 데이타 서비스를 효과적으로 수용할 수 있는 방안이 절실하게 요구되고 있다. 본 논문에서는 음성 뿐만 아니라 다양한 데이타의 서비스 특성을 동시에 고려하여 음성과 데이타에 대해 보다 균형된 서비스 품질을 제공하기 위한 트래픽 처리 방법을 제안 하고 이 방법의 성능을 분석하였다. 성능분석 결과에 따르면 제안된 방법은 이전의 방법에 비해 데이타 품질을 개선할 수 있으며, 데이타의 부하 크기에 무관하게 허용가능한 수준의 음성 블러킹율을 동시에 제공할 수 있음이 확인되었다. 특히 메세지형 데이타서비스도 혼합된 환경 하에서는 성능향상 효과가 더 크다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제2권2호
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• pp.103-119
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• 2008

Traditional web-based services that require users to browse via documents and fill out forms, are difficult to use with mobile devices. Moreover, as the web paradigm assumes active clients, further complications are introduced in cases where the server is the active entity, instead of the client. This paper presents a Server-Centric Interaction Architecture (SCIA) for wireless applications. The architecture enables servers to initiate communication with clients as well as push secure targeted data to them, in a piecemeal fashion. It further enables the development of highly collaborative wireless services with interactive user interfaces.

• 인터넷정보학회논문지
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• 제11권1호
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• pp.15-20
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• 2010

본 논문은 무선 브로드캐스트 환경에서 인접한 노드들로부터의 정보를 활용하여 질의접근시간과 에너지소모를 줄이기 위한 인덱스 기법을 소개한다. 우리는 정보의 선별적 청취를 위해 HLBS라 불리는 3-계층 위치기반 순차적 접근방식의 인덱스를 제안한다. HLBS는 객체들의 위치를 참고한 순차적인 접근탐색 구조를 통해 포인터 없이 모든 객체의 인덱스를 구성한다. HLBS는 단순하고 적은 크기의 인덱스 구조로 무선 브로드캐스트 채널에서 효율적인 정보탐색을 지원한다. 시뮬레이션을 통해 제안 기법의 효율적인 정보검색의 성능을 증명하였다.