• Proceedings of the Acoustical Society of Korea Conference
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• spring
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• pp.327-330
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• 2002

디지털 워터 마킹은 일반적으로 지적 재산권의 보호를 위해서 컨텐츠 소유자가 자신의 컨텐츠에 저작권 정보를 나타내는 워터마크를 삽입하여 제 3자가 허가 없이 디지털 컨텐츠의 사용을 할 경우 불법적인 사용을 막아내는 데 사용된다. 본 논문에서는 워터마킹 기법의 새로운 적용 예로써 인터넷 또는 무선 환경을 통한 멀티미디어 데이터 전송 시 수신된 데이터의 품질을 사용자 측면에서 측정 할 수 있는 방안, 즉 디지털 워터마킹 기법의 새로운 적용 예에 대하여 고찰하였다. 제안하는 방법은 네트워크 상에서 발생하는 패킷 손실, 지연 등의 통계적 해석으로 수신 된 멀티미디어 데이터의 품질을 평가하는 척도로 사용하는 기존의 방법과는 달리 사용자 측면에서 눈으로 보이는 데이터의 일그러짐 정도나, 음질의 왜곡을 정량적인 측정치로 보여 줄 수 있음으로써, 오디오 데이터의 QoS(Quality of Service)를 보장하기 위한 수단이나 수신품질에 따른 차별화 된 과금 결정 등에 활용할 수 있을 것이다. 이를 위해 본 논문에서는 멀티미디어 데이터의 품질 측정을 위한 블라인드 워터마킹 기법을 적용하고 다양한 비트 에러율 (Bit Error Rate, BER)을 갖는 BSC(Binary Symmetric Channel)에 적용시켜 봄으로써 멀티미디어 데이터에 삽입된 워터마크 신호의 검출정도와 수신된 미디어 신호의 PSNR비가 선형적인 분포를 가지게 됨을 확인 할 수 있었다.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2007.04a
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• pp.465-468
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• 2007

This paper addresses the scheme for transmitting Data and TDM signals based on E-PON. E-PON technology, that combines low-cost Ethernet technology and optical fiber infra-structure, has been appeared as a solution of next generation access network. The transmission speed of E-PON is 1Gbps and symmetric in both direction, such as downstream and upstream. Therefore, it is possible to save the cost through sample network architecture, efficient operation, and low maintenance cost of optical IP Ethernet network. By adding TBMoIP(Time Division Multiplexing over Internet Protocol) module to this E-PON system, and implementing QoS(Quality of Service) control function, this system can provide data and TDM service efficiently.

• Journal of the Korea Society of Computer and Information
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• v.25 no.1
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• pp.21-27
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• 2020

In this paper, a hybrid scheduling algorithm is proposed for CMS(Combat Management System) to improve QoS(Quality of Service) based on DWDRR(Dynamic Weighted Deficit Round Robin) and priority-based scheduling method. The main proposed scheme, DWDRR is method of packet transmission through giving weight by traffic of queue and priority. To demonstrate an usefulness of proposed algorithm through simulation, efficiency in special section of the proposed algorithm is proved. Therefore, We propose hybrid algorithm between existing algorithm and proposed algorithm. Also, to prevent frequent scheme conversion, a hysteresis method is applied. The proposed algorithm shows lower packet loss rate and delay in the same traffic than existing algorithm.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.9
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• pp.4242-4263
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• 2017

Multi-User Multiple-Input Multiple-Output (MU-MIMO) technology has recently attracted significant attention from academia and industry because of it is increasingly important role in improving networks' capacity and data rate. Moreover, MU-MIMO systems for the Fifth Generation (5G) have already been researched. High Quality of Service (QoS) and efficient operations at the Medium Access Control (MAC) layer have become key requirements. In this paper, we propose a downlink MU-MIMO MAC protocol based on adaptive Channel State Information (CSI) feedback (called MMM-A) for Wireless Local Area Networks (WLANs). A modified CSMA/CA mechanism using new frame formats is adopted in the proposed protocol. Specifically, the CSI is exchanged between stations (STAs) in an adaptive way, and a packet selection strategy which can guarantee a fairer QoS for scenarios with differentiated traffic is also included in the MMM-A protocol. We then derive the expressions of the throughput and access delay, and analyze the performance of the protocol. It is easy to find that the MMM-A protocol outperforms the commonly used protocols in terms of the saturated throughput and access delay through simulation and analysis results.

• Journal of KIISE:Information Networking
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• v.27 no.4
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• pp.441-452
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• 2000

이동 컴퓨팅 환경에서 멀티미디어 트래픽을 효율적으로 지원하기 위해서 가장 중요한 이슈는 이동호스트(클라이언트)에게 QoS(Quality of Service)를 지속적으로 보장하는 것이다. 그러나 핸드-오프를 필요로하는 클라이언트의 이동성으로 인해 클라이언트와 네트워크간에 협상된 QoS가 보장되지 못할 수도 있다. 본 논문은 이동 컴퓨팅 환경에서 클라이언트에게 지속적으로 QoS를 지원하기 위한 ARMM을 제안하였다. 각 셀은 핸드-오프 호를 위해 이웃 셀에게 대역폭을 예약하며 예약된 대역폭은 단지 핸드-오프 호들만이 사용할 수 있다 만약 핸드-오프 호를 위해 대역폭을 너무 많이 예약한다면 신규 호의 블록킹 확률이 증가하므로 예약할 대역폭의 크기를 정확히 결정하는 것이 중요하다 본 논문에서는 이 대역폭의 정확한 크기를 결정하고 네트워크 상태에 따라 크기를 적응적으로 조정하기 위해 MPP와 2-계층 셀 구조를 기반으로 한 기법을 제안하였다. 본 논문에서 제시된 대역폭 예약 메커니즘의 성능을 평가하기 위해 신규 호블록킹률, 핸트-오프 호 종료율 대역폭 이용률을 측정하였다. 시뮬레이션 결과 본 논문의 대역폭 예약 메커니즘의 성능이 No Reservation Fixed Reservation Adaptive Reservation과 같은 기존의 메커니즘보다 우수함을 알수 있었다.

• Proceedings of the Korea Contents Association Conference
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• 2007.11a
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• pp.611-614
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• 2007

The IEEE 802.11 Task Group E has worked to enhance the legacy 802.11 MAC to expand support for applications with QoS requirements. EDCF(Enhanced Distributed Coordination Function) of IEEE 802.11e is enhanced from DCF(Distributed Coordination Function) of 802.11 and It has differential AC(Access Category). In this paper, we change parameters(AIFS, CWmax) and make an analysis of network performance. We use NS-2 to verify change of network performance.

• Journal of Satellite, Information and Communications
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• v.11 no.2
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• pp.55-59
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• 2016

Conventional RF energy harvesting systems can harvest energy and decode information from same source as an Hybirid-AP (H-AP). However, harvesting efficiency is seriously dependent on distance between users and H-AP. Therefore, in this paper, we proposed a transmission model for RF harvesting consisting of information and power source separately called Decoupled RF Energy harvesting networks. Main purpose of this paper is to maximize energy efficiency under various constraints of transmit power from H-AP and power beacon (PB), minimum quality of service and quality of harvested power of each users. To measure proposed model's performance, we proposed optimal time scheduling algorithms for energy efficiency (EE) maximization using Lagrangian dual decomposition theory that locally maximizes the EE by obtaining suboptimal values of three arguments : transmit power of H-AP, transmit power of PB, frame splitting factor. Experiment results show that the proposed energy-efficient algorithms converge within a few iterations with its optimality and greatly improve the EE compared to that of baseline schemes.

• The Journal of the Korea institute of electronic communication sciences
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• v.5 no.3
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• pp.269-274
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• 2010

Recently IPTV service is becoming an emerging service representing IP convergence that is enabled on the broadband networks. It is an essential and very important issue to manage the service quality of IPTV service effectively for its successful deployment because of the innate nature of current Internet that cannot support quality of service (QoS). In particular, it is required that subscriber can measure and judge the service quality of IPTV service directly, which is impossible with the current method usually depending on a measurement equipment. In this paper, therefore, we introduce an implementation of a software that is installed at a set-top on the subscriber side and measures the quality of IPTV service in real time. In order to verify the performance of the implemented software, we perform a number of tests and compare the result with the measurement equipments in common use. By the comparison, it is shown that the measurement by the implemented software is precise and reliable.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.2
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• pp.834-841
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• 2012

In order to the mobile service uses the wireless terminal including the development of the wire wireless network and Smart phone, and etc. use including mobile office, which and etc. increases. Because in order that the u-Healthcare service using this appeared before the footlights and the existing quality measurement reference considered the speed, error rate, and etc. just, guarantees the stability of the u-Healthcare, the quality control by service are necessary. In this paper, the quality measurement reference by mobile service considering the radio environment as the method for satisfying the quality guarantee of the u-Healthcare mobile service user and user needs was presented. The WiBro u-Healthcare wireless data service quality based system in the end user perspective was established through the main performance index and entrepreneur case presented in the international standardization institute including 3GPP, WiMAX forum, GSMA, and etc. through the related research and the validity of the quality index establishment was presented according to each service.

• ETRI Journal
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• v.29 no.1
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• pp.113-115
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• 2007

A dynamic tri-threshold call admission control scheme has been developed. This scheme supports voice, data, and multimedia services and it complies with the universal mobile telecommunications system. The performance of the proposed scheme is evaluated under varying handover rates. The QoS performance-including channel utilization, call dropping probability, and blocking probability-is investigated. The performance of the developed scheme is found to be encouraging.