• 한국멀티미디어학회논문지
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• 제16권1호
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• pp.50-55
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• 2013

This article presents a simple and reasonable in-service, real-time, and continuous single-ended objective video quality assessment model for DTV broadcasting using a multiburst signal at the bottom of the transient effect area, similar to Vertical Interval Test Signals. The issue of in-service video-quality monitoring in DTV broadcasting is addressed, and an effective method of quality monitoring is presented. The proposed method is also implemented and tested in a range of situations using a simulated HDTV broadcasting network.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제8권10호
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• pp.3361-3377
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• 2014

Synchronous computing models provided by real-time synchrony protocols, such as TTA [1] and PALS [2], greatly simplify the design, implementation, and verification of real-time distributed systems. However, their application to real systems has been limited since their assumptions on underlying systems are hard to satisfy. In particular, most previous real-time synchrony protocols hypothesize the existence of underlying fault tolerant real-time networks. This, however, might not be true in most soft real-time applications. In this paper, we propose a practical approach to a synchrony protocol, called Quality-Aware PALS (qPALS), which provides the benefits of a synchronous computing model in environments where no fault-tolerant real-time network is available. qPALS supports two flexible global synchronization protocols: one tailored for the performance and the other for the correctness of synchronization. Hence, applications can make a negotiation flexibly between performance and correctness. In qPALS, the Quality-of-Service (QoS) on synchronization and consistency is specified in a probabilistic manner, and the specified QoS is supported under dynamic and unpredictable network environments via a control-theoretic approach. Our simulation results show that qPALS supports highly reliable synchronization for critical events while still supporting the efficiency and performance even when the underlying network is not stable.

• 한국도시철도학회논문집
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• 제6권4호
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• pp.351-361
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• 2018

본 논문에서는 실시간 통합 철도 안전 감시 시스템의 데이터 전송 품질 요구 사항을 만족시키기 위해 OMG DDS 표준에서 제공하는 네트워크 전송 품질을 제어 할 수 있는 DDS(Data Distribution Service) QoS(Quality of Service)에 관한 실험을 통한 분석을 진행하였다. '실시간 통합 철도 안전 감시제어시스템'은 철도 분야에서 다양한 센서의 데이터를 수집 및 분석하여 잠재적인 철도사고 위험을 예측하고 방지하는 시스템이다. 이 시스템에서 수집된 데이터를 정확하고 안정적으로 실시간으로 전송하려면 데이터 전송 품질을 보장해야 한다. 실험 결과에 따르면 DDS QoS를 사용하여 철도 안전을 모니터링하고 제어하기 위해 실시간으로 정확하고 안정적인 데이터 전송을 보장할 수 있다.

• 품질경영학회지
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• 제18권1호
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• pp.21-28
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• 1990

In this paper, the capacity of system which provides the real time response call service to the customer is studied. The quality of call service depends on the response time of the service in the system. Therefore, the focus of this paper is to investigate the capacity of system under the restriction of response time. In this paper, the system is modeled by queueing network. The analytical method is applied to solve this queueing network. The solution of the model has product form solution. To get the reasonable capacities, nonlinear programming problem is formulated and is solved by GINO.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제11권10호
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• pp.4823-4843
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• 2017

In this paper, an improved utility-based cross-layer dynamic subcarrier allocation (DSA) algorithm is proposed for single carrier frequency division multiple access (SC-FDMA) system, which adopts adaptive service rate control (ASRC) to eliminate the service rate waste and improve the spectral efficiency in heterogeneous network including non-real-time traffic and real-time traffic. In this algorithm, furthermore, a first in first out (FIFO) queuing model with finite space is established on the cross-layer scheduling framework. Simulation results indicate that by taking the service rate constraint as the necessary condition for optimality, the ASRC algorithm can effectively eliminate the service rate waste without compromising the scheduling performance. Moreover, the ASRC algorithm is able to further improve the quality of service (QoS) performance and transmission throughput by contributing an attractive performance trade-off between real-time and non-real-time applications.

• 한국정보통신학회논문지
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• 제2권3호
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• pp.401-408
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• 1998

최근 들어서 실시간 제어, 오디오/비디오 회의, Medical image등의 실시간에 관한 다양한 응용들이 출현하고 있으며 이들은 하부 통신 서브 시스템 (Underlying communication subsystem) 에서 각기의 일정한 QoS (Quality of Service)를 요구한다. 이 경우 통신 서브시스템은 각각의 응용들에 관한 QoS 요구를 만족시키는 실시간 통신 서비스를 제공하여야 하며 동시에 최적의 트래픽을 유지하기 위한 성능을 제공하여야 한다. 본 논문에서 고려하는 단대 단 망은 고 대역폭과 확장성을 내재하고 있음으로 인하여 분산 시스템에 대하여는 자연 적인 플랫폼을 제공하는 것으로 볼 수 있다. 본 논문에서는 QoS를 만족하는 단대 단 망에서의 실시간 프로토콜에 대해 살펴보고, 효율적인 실시간 채널의 디자인 요소(Design Factors)를 제안한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제15권11호
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• pp.3913-3934
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• 2021

Real-time prediction of Web service of quality (QoS) provides more convenience for web services in cloud environment, but real-time QoS prediction faces severe challenges, especially under the cold-start situation. Existing literatures of real-time QoS predicting ignore that the QoS of a user/service is related to the QoS of other users/services. For example, users/services belonging to the same group of category will have similar QoS values. All of the methods ignore the group relationship because of the complexity of the model. Based on this, we propose a real-time Matrix Factorization based Clustering model (MFC), which uses category information as a new regularization term of the loss function. Specifically, in order to meet the real-time characteristic of the real-time prediction model, and to minimize the complexity of the model, we first map the QoS values of a large number of users/services to a lower-dimensional space by the PCA method, and then use the K-means algorithm calculates user/service category information, and use the average result to obtain a stable final clustering result. Extensive experiments on real-word datasets demonstrate that MFC outperforms other state-of-the-art prediction algorithms.

• 한국융합학회논문지
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• 제8권9호
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• pp.249-254
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• 2017

본 연구는 모바일 부동산 서비스의 정보 품질과 허위매물의 개선방안을 검색 필터 서비스를 통해 성장 가능할 방안을 제공하였다. 현재 활발하게 사용 중인 각국의 대표적인 모바일 부동산 앱의 사례를 비교했으며 부동산 정보 탐색 시 가장 먼저 필요한 검색 필터 13개를 채택하여 사용성과 서비스 상태를 분석했다. 그 결과 모바일 부동산 서비스 정의 맞게 사용자들이 언제 어디서나 유기적으로 신속하며 신뢰성 있는 정보를 받기 위해서는 수준 높은 검색 필터 서비스 공급이 정보품질 개선을 위해 필수적이다. 결국, 허위매물에 대한 사후적인 대책 마련보다는 사전 검수가 야기되며 사용자의 니즈에 충족되어 보다 개선된 검색 필터 서비스를 제공하여 모바일 부동산 중개 서비스의 정의에 맞게 시간과 공간에 제약받지 않고 신뢰할 수 있는 정보품질의 서비스를 공급하는 것이 허위매물의 피해자를 사전적으로 예방하는 것이라 말할 수 있다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제5권1호
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• pp.123-140
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• 2011

In this paper, we propose an Energy Efficient Media Access Control (EE-MAC) protocol for wireless sensor networks. The proposed scheme is designed to save power consumption and guarantee quality-of-service for real-time traffic. EE-MAC uses the superframe structure which is bounded by the transmission of a beacon frame and can have an active and an inactive portion. The active period is divided into the contention free period (CFP) for real-time traffic transmission and the contention access period (CAP) for non-real-time traffic transmission. We propose the exclusively allocated backoff scheme which assigns a unique backoff time value to each real-time node based on bandwidth allocation and admission control. This scheme can avoid collision between real-time nodes by controlling distributed fashion and take effect a statistical time division multiple access. We also propose the algorithm to change the duty cycle adaptively according to channel utilization of media depending on network traffic load. This algorithm can prolong network lifetime by reducing the amount of energy wasted on idle listening.

• 한국정밀공학회지
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• 제26권10호
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• pp.40-46
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• 2009

Recently CAN (Controller Area Network) is widely used as an in-vehicle networking protocol for intelligent vehicle. The identifier field (ID) of CAN is used not only to differentiate the messages but also to give different priorities to access the bus. This paper presents a dynamic 10 allocation algorithm in order to enhance the real-time quality-of-service (QoS) performance. When the network traffic is increased, this algorithm can allocate a network resource to lower priority message without degradation of the real-time QoS performance of higher priority message. In order to demonstrate the algorithm's feasibility, message transmission delays have been measured with and without the algorithm on an experimental network test bed.