• 한국통신학회논문지
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• 제35권7B호
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• pp.1018-1033
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• 2010

최근 이동 단말기 사용이 일반화 되면서 이동성을 전제로 한 고속 인터넷 서비스에 대한 수요가 점차 증가하고 있으며, 사용자들은 유무선 통합 환경을 통하여 언제 어디서나 자유롭게 원하는 콘텐츠를 다양한 단말에서 제공받기를 원하고 있다. 이에 따라 단말의 이동성을 지원하는 여러 가지 메커니즘이 제안되었지만, 이러한 메커니즘들은 모바일 멀티캐스트 환경에서 끊기지 않는 이동성과 서비스 품질 보장을 지원해주기 어렵다. 본 논문에서는 이러한 사용자의 요구에 따라 모바일 IPTV 서비스 등과 같은 고품질 실시간 서비스를 유무선 통합 환경에서 효과적으로 제공해줄 수 있으며 서비스 품질 보장도 고려된 핸드오버 메커니즘을 제안하였다. 제안한 메커니즘은 유선망에서의 probing 기반 수락제어를 통한 서비스 품질 보장 방법을 PMIPv6 기반의 무선망까지 확장한 유무선 통합 망에서 2계층 멀티캐스트 정보 관리 기법으로 멀티캐스트 수락제어 및 핸드오버를 관리한다. 또한 네트워크 시뮬레이터 ㎱-2를 사용하여 제안한 메커니즘의 성능과 특성을 분석하였다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권3호
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• pp.1260-1281
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• 2015

As the number of services available on the Web increases, it is vital to be able to identify which services can be trusted. Since there can be an extremely large number of potential services that offer similar functionality, it is challenging to select the right ones. Service requestors have to decide which services closelysatisfy their needs, and theymust worry about the reliability of the service provider. Although an individual service can be trusted, a composed service is not guaranteed to be trustworthy. In this paper, we present a trust model that supports service discovery and composition based on trustworthiness. We define a method to evaluate trust in order to discover trustworthy services. We also provide a method to perform trust estimation for dynamic service composition, and we present results of two experiments. The proposed model allows for service requestors to obtain the most trustworthy services possible. Our mechanism uses direct and indirect user experience to discover the trustworthiness of the services and service providers. Moreover, composing services based on quantitative trust measurements will allow for consumers to acquire a highly reliable service that meet their quality and functional requirements.

• 한국병원경영학회지
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• 제25권4호
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• pp.29-37
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• 2020

Purposes: This study purposed to identify influence of postpartum care services on health-related quality of life in women after birth. Methodology: Korea Health Panel Survey 2009-2015 provided by the Korea Institute for Health and Social Affairs and National Health Insurance Service was used for the analysis. The health-related quality of life evaluate as a EuroQoL-5D(EQ-5D-3L, used the weight of the CDC) was used as dependent variables. Postpartum care services was used as independent variable. Demographic factors(education, economic activity, region, house income), health related variable(presence of chronic disease, self-rated health), birth related variable(birth-related problem, childbirth, pregnancy of advanced maternal age) used as covariates. Regression analysis was used. Findings: The rate of use of postpartum care services is increasing year by year. Postpartum care services and self-rated health positively influence on the health-related quality of life in women after birth and chronic disease and birth-related problem negatively influence on. Practical Implications: Therefore, it is necessary that the government's policy of the postpartum care service be expanded and systematized to increase accessibility on. There are rare studies on the health-related quality of life of women after childbirth, adjusted for birth-related variables. So this study has significance.

• 한국콘텐츠학회논문지
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• 제7권1호
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• pp.94-102
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• 2007

현재 무선 인터넷을 위한 패킷 데이터 서비스가 'WiBro WLAN 3G'를 통해 제공되고 있으나 개별망에서는 Seamless한 환경을 만족시키기 어렵다. 그리고 WiBro와 WLAN은 서비스영역이 상대적으로 작아 광역서비스 제공시 기지국수가 늘어나게 된다. 따라서 이용자는 이동시 연속적이고 끊김없는 데이터서비스를 이용할 수 있으며, 사업자는 망 구축비용 및 운용비용 절감을 얻기 위해 통합연동망을 도입할 필요성이 있다. 따라서 본 논문에서는 SDR 공용기지국환경에서 '사용자요구대역폭'과 '단말이동속도', '단말서비스셀지역'을 고려한 새로운 핸드오프 알고리즘을 제안하고 대역할당, QoS 만족도, 핸드오프 실패율의 우수성을 확인하였다.

• 디지털산업정보학회논문지
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• 제5권4호
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• pp.117-126
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• 2009

The recent interest in sensor networks has led to a number of routing schemes that use the limited resources available at sensor nodes more efficiently. These schemes typically try to find the minimum energy path to optimize energy usage at a node. Some schemes, however, are prone to unbalance of the traffic and energy. To solve this problem, we propose a novel solution: a gradient-field approach which takes account of the minimum cost data delivery, energy consumption balancing, and traffic equalization. We also modify the backoff-based cost field setup algorithm to establish our gradient-field based sensor network and give the algorithm. Simulation results show that the overhead of routing establishment obtained by our algorithm is much less than the one obtained by Flooding. What's more, our approach guarantees the basic Quality of Service (QoS) without extra spending.

• Journal of Communications and Networks
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• 제10권1호
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• pp.38-43
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• 2008

In this paper, adaptive channel borrowing approach fuzzy neural networks for load balancing (ACB-FNN) is presented to maximized the number of served calls and the depending on asymmetries traffic load problem. In a wireless network, the call's arrival rate, the call duration and the communication overhead between the base station and the mobile switch center are vague and uncertain. A new load balancing algorithm with cell involved negotiation is also presented in this paper. The ACB-FNN exhibits better learning abilities, optimization abilities, robustness, and fault-tolerant capability thus yielding better performance compared with other algorithms. It aims to efficiently satisfy their diverse quality-of-service (QoS) requirements. The results show that our algorithm has lower blocking rate, lower dropping rate, less update overhead, and shorter channel acquisition delay than previous methods.

• International journal of advanced smart convergence
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• 제12권2호
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• pp.173-181
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• 2023

Data collection is an essential element in the construction and operation of a smart factory. The quality of data collection is greatly influenced by network conditions, and existing wireless network systems for IoT inevitably lose data due to wireless signal strength. This data loss has contributed to increased system instability due to misinformation based on incorrect data. In this study, I designed a distributed MQTT IoT smart sensor and gateway structure that supports wireless multicasting for smooth sensor data collection. Through this, it was possible to derive significant results in the service latency and data loss rate of packets even in a wireless environment, unlike the MQTT QoS-based system. Therefore, through this study, it will be possible to implement a data collection management system optimized for the domestic smart factory manufacturing environment that can prevent data loss and delay due to abnormal data generation and minimize the input of management personnel.

• Journal of Communications and Networks
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• 제8권4호
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• pp.401-409
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• 2006

Orthogonal frequency division multiplexing (OFDM) and multiple input multiple output (MIMO) technologies provide additional dimensions of freedom with spectral and spatial resources for radio resource management. Multi-dimensional radio resource management has recently been identified to exploit the full dimensions of freedom for more flexible and efficient utilization of scarce radio spectrum while provide diverse quality of service (QoS) guarantees. In this work, a multi-dimensional radio resource scheduling scheme is proposed to achieve above goals in hybrid orthogonal frequency division multiple access (OFDMA) and space division multiple access (SDMA) systems. Cochannel interference (CCI) introduced by frequency reuse under SDMA is eliminated by frequency division and time division between highly interfered users. This scheme maximizes system throughput subjected to the minimum data rate guarantee. for heterogeneous users and transmit power constraint. By numerical examples, system throughput and fairness superiority of the our scheduling scheme are verified.

• 한국콘텐츠학회논문지
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• 제10권9호
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• pp.36-44
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• 2010

본 논문은 차세대 통합망 환경에서 IPTV와 같은 영상 스트리밍 서비스를 위해 종단간 가용대역폭 모니터링을 통하여 영상 품질을 제어할 수 있는 영상 품질 제어 시스템(VQCS)을 제안한다. IPTV 서비스를 통해 영상, 음성 및 게임과 같은 다양한 멀티미디어 서비스들을 제공할 수 있으며 이런 서비스들은 대용량의 대역폭을 소비하게 된다. 이때 네트워크 가용대역폭이 부족할 경우 영상 끊김, 형태 왜곡 및 잔상과 같은 영상 품질 저하가 발생하게 된다. 영상 스트리밍 서비스의 품질을 안정적으로 제어하기 위해서는 가용대역폭 모니터링 방안이 요구된다. 이에 우리는 단말 내의 영상 품질 제어 시스템에서 IP 헤더 내의 전체길이(Total Length) 필드를 이용하여 단위시간 동안 링크를 점유하고 있는 패킷 양 계산을 통해 가용 대역폭을 측정하였으며, 가용대역폭 정보를 기반으로 네트워크 내의 스케일러빌리티 추출기는 영상 스트림 데이터율을 적응적으로 선택하여 대역폭 부족으로 인한 영상 스트리밍의 품질 저하를 막아 서비스 품질을 향상시킬 수 있다.

• 전자공학회논문지CI
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• 제45권5호
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• pp.125-133
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• 2008

본 논문은 다양한 서비스 클래스가 제공되는 BcN (Broadband convergence Network) 환경에서 상위 우선순위 서비스의 품질을 보장하기 위한 능동 큐 관리 메커니즘 (Active-WRED)을 제안한다. 네트워크 혼잡 상황에서 제안된 메커니즘은 상대적으로 낮은 우선순위를 갖는 서비스의 drop 확률을 증가시키고 이에 따라 상위 우선순위 서비스의 drop 확률을 감소시킴으로써 상위 우선순위 서비스에 대해 패킷 손실로부터 품질을 보장할 수 있다. 제안된 능동 큐 관리 메커니즘의 성능을 분석하기 위해 이산 시간 큐잉 시스템의 통계적 분석 방법을 도입하였다. 두 서비스 클래스 (GS: Guaranteed Service, BS: Best Effort Service)만을 고려하여 제안 방안의 성능 분석을 위해 MMBP-2 (two-state Markov-Modulated Bernoulli arrival Process) 트래픽 소스 모델과 2차 이산시간 Markov 체인을 도입하였다.