• Journal of information and communication convergence engineering
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• 제10권1호
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• pp.21-26
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• 2012

As the new requirements for wireless sensor networks are emerging, real-time communications is becoming a major research challenge because resource-constrained sensor nodes are not powerful enough to accommodate the complexity of the protocol. In addition, an efficient energy management scheme has naturally been a concern in wireless sensor networks for a long time. However, the existing schemes are limited to meeting one of these two requirements. To address the two factors together, we propose real-time communications with two approaches, a protocol for satisfied conditions and one for unsatisfied. Under the satisfied requirement, existing real-time protocol is employed. On the other hand, for the unsatisfied requirement, the newly developed scheme replaces the existing scheme by adjusting the transmission range of some surplus nodes. By expanding the transmission range, the end-to-end delay is shortened because the number of intermediate nodes decreases. These nodes conserve their energy for real-time communications by avoiding other activities such as sensing, forwarding, and computing. Finally, simulation results are given to demonstrate the feasibility of the proposed scheme in high traffic environments.

• Journal of Astronomy and Space Sciences
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• 제19권4호
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• pp.403-408
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• 2002

3D display of spacecraft motion by using telemetry data received from satellite in real-time is described. Telemetry data are converted to the appropriate form for 3-D display by the real-time preprocessor. Stored playback telemetry data also can be processed for the display. 3D display of spacecraft motion by using real telemetry data provides intuitive comprehension of spacecraft dynamics.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2007년도 한국컴퓨터종합학술대회논문집 Vol.34 No.1 (B)
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• pp.298-303
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• 2007

비휘발성 메모리의 하나인 플래시 메모리는 저전력 및 저비용 등의 장점으로 인해 임베디드 시스템에 필수적인 요소로 사용되고 있다. 이러한 장점에 반해, DRAM과 같은 휘발성 반도체 메모리와 비교하여 데이터 쓰기는 느리고, 데이터 업데이트를 위한 블록 소거 (erase) 동작의 오버헤드라는 단점이 있다. 특히 블록 소거 동작은 횟수가 제한되어 있으며, 이는 플래시 메모리의 수명을 결정하는데 중요한 요소이다. 본 논문에서는 플래시 메모리 기반 파일시스템에서 DRAM과 같은 동적 메모리를 사용하여 블록 소거의 횟수를 줄이고 입출력 속도를 향상시키는 기법을 제안한다.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 1999년도 추계종합학술대회 논문집
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• pp.125-128
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• 1999

In this paper, we propose a QoS-sensitive admission threshold method for the transmission of the non-real tine data packet such that the quality of services for both voice and data traffics are maintained to a required level. By detecting the active voice traffic during the current time slot, the non-real-time data packets are transmitted up to an admission threshold level during the next time slot. We found out that the optimum admission threshold is four voice traffic resources lower from the maximum allowable threshold to maintain the outage probability within 1% when the connected voice users are 15.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.691-694
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• 2003

This paper describes how to use Profibus networks to support real-time industrial communications, that is, how to ensure the transmission of real-time messages within a maximum bound time. Profibus is based on a simplified timed token protocol, which is a well-proved solution for the real-time communication systems. However, Profibus differs from the timed token protocol, thus the usual timed token protocol has to be modified in order to be applied in Profibus. In fact, the real-time solutions for networks based on the timed token protocol rely on the possibility of allocating specific bandwidth for the real-time traffic. This means that a minimum amount of time to transmit the real-time messages is always guaranteed whenever each token is arrived. In other words, with the Profibus protocol, at least, one real-time message should be transmitted per every token visit in the worst case. It is required to control medium access properly to satisfy the message deadlines. In this paper, we have presented how to obtain the optimal network parameter for the Profibus protocol. The selected network parameter is valid regardless of the behavior of asynchronous messages.

• ETRI Journal
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• 제35권4호
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• pp.726-729
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• 2013

For secure multimedia communications, existing encryption techniques use an online session key for the key exchange, for which key size is limited to less than 10 digits to accommodate the latency condition caused by user devices only being able to handle low computational loads. This condition results in poor security of recorded encrypted data. In this letter, we propose a packet key scheme that encrypts real-time packets using a different key per packet for multimedia applications. Therefore, a key of a relatively small size can provide after-transmission confidentiality to data of a real-time session.

• 한국정보과학회:학술대회논문집
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• 한국정보과학회 2005년도 한국컴퓨터종합학술대회 논문집 Vol.32 No.1 (A)
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• pp.430-432
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• 2005

센서 네트워크를 구성하는 대부분의 센서 노드들은 제한된 용량의 배터리로부터 전력을 공급받는다. 그러한 센서 노드들의 수명은 장착된 배터리의 수명에 의해 결정되기 때문에 배터리의 수명을 최대화시키는 것이 센서 네트워크 응용 설계에서 중요한 고려 사항이 된다. 한편, 배터리는 전력 소모 패턴에 따라 전지가 제공할 수 있는 총 용량이 일정하지 않으며 방전이 진행됨에 따라서 비선형적인 특성을 보이기 때문에, 배터리의 수명은 연결된 로드의 특성에 따라서 항상 다르게 결정된다. 본 논문에서는 그러한 배터리의 방전 특성을 고려한 실시간 태스크 스케줄링 알고리즘을 제안한다. 실험을 통하여 얻은 결과는 제안된 배터리의 특성을 고려한 태스크 스케줄링 알고리즘이 그렇지 않은 태스크 스케줄링 알고리즘에 비해 배터리 수명을 향상시킴을 보인다.

• 한국HCI학회:학술대회논문집
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• 한국HCI학회 2007년도 학술대회 3부
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• pp.318-321
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• 2007

This paper proposes a GPU-based approach to real-time skinning animation of large crowds, where each character is animated independently of the others. In the first pass of the proposed approach, skinning is done by a pixel shader and the transformed vertex data are written into the render target texture. With the transformed vertices, the second pass renders the large crowds. The proposed approach is attractive for real-time applications such as video games.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2000년도 ITC-CSCC -2
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• pp.747-749
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• 2000

A new scheduling algorithm called the Adaptive Weighted Round Robin with Delay Tolerance (AWRR/DT) is presented. The proposed scheme can reduce the average delay of non-real-time (NRT) class while maintaining the QoS of real-time (RT) classes. Our scheme can also reflect the traffic fluctuation of networks with a small processing burden.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2005년도 ICCAS
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• pp.1836-1839
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• 2005

We have developed Ethernet based real-time communication systems called "Vnet/IP" for DCS which is the control system for process automation. This paper describes the features and the technologies of the ASIC which is utilized in the communication interface hardware for Vnet/IP. Vnet/IP has been developed for mission-critical communications. Hence it has real-time feature, high reliability and precise time synchronization capability. At the same time, it is able to deal with standard protocols without influence on mission-critical communications. The communication interface hardware has a host interface and dual redundant network interfaces. The host interface can be chosen PCI-bus or R-bus which is the proprietary internal bus developed for the high reliable redundant controller. Each network interface is a RJ45 connection with 1Gbps maximum in compliance with IEEE802.3.