• The Journal of Korean Institute of Communications and Information Sciences
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• v.36 no.4B
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• pp.314-321
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• 2011

There have been considerable standardization works to measure subjective video quality. However, these standardization methods are based on the situation where they have original or reference video sequences, and measure the video quality by looking the sequence during short time duration, e.g. 10 seconds. Since people's TV watching time durations in IPTV services are very long (e.g. more than 30 minutes), the quality measurements by the standards are not practical. In this paper, we analyze the effect of video quality rating period to MOS (Mean Opinion Score), and suggest a proper rating duration of subjective video quality for IPTV services.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.6 no.4
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• pp.552-558
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• 2002

Differentiated services (DiffServ) architecture defines a new framework for the support of quality of service (QoS) in IP-based networks. RIO has received the most attention among all the active queue management mechanisms proposed for assured service in DiffServ environment. The paper proposed the enhanced RIO which could alleviate the impact of flow's packet sire on the realized throughput. The simulation results indicate that this mechanism, when combined with TSW as traffic conditioner, provide better throughput assurance and fair distribution of excess bandwidth independent of packet size of flows in case of well-provisioned network environment.

• Proceedings of the IEEK Conference
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• 2004.06a
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• pp.171-174
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• 2004

Packet classification is an essential architectural component in implementing the quality-of-service (QoS) in today's Internet which provides a best-effort service to ail of its applications. Multiple header fields of incoming packets are compared against a set of rules in packet classification, the highest priority rule among matched rules is selected, and the packet is treated according to the action of the rule. In this Paper, we proposed a new packet classification scheme based on parallel multiple hashing on tuple spaces. Simulation results using real classifiers show that the proposed scheme provides very good performance on the required number of memory accesses and the memory size compared with previous works.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.29 no.9B
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• pp.771-777
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• 2004

In a COMA system, the capacity is variable and mainly depends on multiple access interference. The multiple access interference has a deep relationship with transmitted or received power. The capacity of COMA2000 system is considered to be limited by the forward link capacity. In this paper, we show that the forward link cell load can be represented by the total transmitted power of base station and we propose a forward link call admission control (CAC) strategy for COMA2000 system. The proposed call admission scheme adopts the rate control algorithm for data call. This call admission scheme enables the system to utilize radio resource dynamically by controlling data rate according to the cell load status, and enhance the system throughput and grade of service (GoS). quality of service(QoS) such as blocking and outage probability.

• Annual Conference of KIPS
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• 2012.04a
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• pp.714-717
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• 2012

통신기술의 발전으로 사람과 사람의 의사소통에 있어서 IT 기술을 접목시킨 여러 기술들이 발전하고 있다. SIP 기반의 UC 서비스 또한 기업과 고객의 원활한 커뮤니케이션을 위하여 기술이 꾸준히 발전하고 있다. 그러나 UC 서비스 또한 IP 기반의 서비스이기 때문에 여러 가지 보안위협의 노출이 되어 있다. SIP 기반의 서비스는 QoS(Quality of Servic)가 보장되어야 하지만 품질에 중점을 두어 보안위협에 크게 노출 되어 있는 것이 사실이다. 이에 본 논문에서는 SIP 보안 메커니즘인 HTTP Digest 사용자 인증, TLS 홉간 보안, S/MIME을 이용한 단말간의 보안 메커니즘을 적용하고 Virtual Proxy Server를 이용한 보안 시스템을 설계 하였다.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2011.07a
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• pp.102-104
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• 2011

최근 비디오 스트리밍과 대화형 비디오 서비스 등과 같은 광대역 멀티미디어 서비스를 지원하기 위하여 Wimax와 같은 4G 무선네트워크 시스템 기술이 발전해 왔다. 4G 무선네트워크의 OFDM(Orthogonal Frequency Division Multiplexing)과 MIMO(multi Input Multi Output)은 사용자들에게 매우 유연한 QoS(Quality of Service) 서비스를 제공해 줄 수 있다.[1] 이 논문에서는 다양한 네트워크 상황에서 멀티캐스트 그룹에게 효율적인 방법으로 통신 자원을 할당하기 위해 OFDM 방법을 사용 하였다. 이에 본 논문에서는 한 셀(cell) 내의 서로 다른 멀티캐스트의 그룹의 다른 SNR(Signal to noise Ratio)의 사용자 분포에 따른 적응적인 scalable 비디오 멀티캐스트 방식을 제안한다. 더 나은 수신율을 가진 사용자는 최적의 MCS(Modulation and Coding Scheme) 할당을 통해 서로 다른 화질의 scalable 비디오 계층 중 높은 해상도의 비디오를 받을 수 있다. 논문에서는 전체 전송률을 최적화 하는 대신 전송받은 전체 비디오의 평균 화질을 최적화하는 방법을 제안한다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.2
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• pp.618-633
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• 2014

Relay technology is becoming more important for mobile communications and wireless internet of things (IoT) networking because of the extended access network coverage range and reliable quality of service (QoS) it can provide at low power consumption levels. Existing mobile multihop relay (MMR) technology uses fixed-point stationary relay stations (RSs) and a divided time-frame (or frequency-band) to support the relay operation. This approach has limitations when a local fixed-point stationary RS does not exist. In addition, since the time-frame (or frequency-band) channel resources are pre-divided for the relay operation, there is no way to achieve high channel utilization using intelligent opportunistic techniques. In this paper, a different approach is considered, where the use of mobile/IoT devices as RSs is considered. In applications that use mobile/IoT devices as relay systems, due to the very limited battery energy of a mobile/IoT device and unequal channel conditions to and from the RS, both minimum energy consumption and QoS support must be considered simultaneously in the selection and configuration of RSs. Therefore, in this paper, a mobile RS is selected and configured with the objective of minimizing power consumption while satisfying end-to-end data rate and bit error rate (BER) requirements. For the RS, both downlink (DL) to the destination system (DS) (i.e., IoT device or user equipment (UE)) and uplink (UL) to the base station (BS) need to be adaptively configured (using adaptive modulation and power control) to minimize power consumption while satisfying the end-to-end QoS constraints. This paper proposes a minimum transmission power consuming RS selection and configuration (MPRSC) scheme, where the RS uses cognitive radio (CR) sub-channels when communicating with the DS, and therefore the scheme is named MPRSC-CR. The proposed MPRSC-CR scheme is activated when a DS moves out of the BS's QoS supportive coverage range. In this case, data transmissions between the RS and BS use the assigned primary channel that the DS had been using, and data transmissions between the RS and DS use CR sub-channels. The simulation results demonstrate that the proposed MPRSC-CR scheme extends the coverage range of the BS and minimizes the power consumption of the RS through optimal selection and configuration of a RS.

• Journal of information and communication convergence engineering
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• v.6 no.2
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• pp.122-128
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• 2008

Multiprocessor architectures and platforms, such as, a multiprocessor system on chip (MPSoC) recently introduced to extend the applicability of the Moore's law, depend upon concurrency and synchronization in both software and hardware to enhance design productivity and system performance. With the rapidly approaching billion transistors era, some of the main problem in deep sub-micron technologies characterized by gate lengths in the range of 60-90 nm will arise from non scalable wire delays, errors in signal integrity and non-synchronized communication. These problems may be addressed by the use of Network on Chip (NOC) architecture for future System-on-Chip (SoC). We have modeled a concurrent architecture for a customizable and scalable NOC in a system level modeling environment using MLDesigner (from MLD Inc.). Varying network loads under various traffic scenarios were applied to obtain realistic performance metrics. We provide the simulation results for latency as a function of the buffer size. We have abstracted the area results for NOC components from its FPGA implementation. Modeled NOC architecture supports three different levels of quality-of-service (QoS).

• Journal of Digital Convergence
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• v.11 no.12
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• pp.353-359
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• 2013

The search method that web services offers has its limitations. The search service considers only functional factors based on the client's preferences. In order to improve the web service search - which alone only considers functional factors - our research introduces an execution phase which performs both functional and non-functional factors by utilizing WSDL and matching information. Our research studies the architecture of both the service selecting method and the selecting process to help determine the best service solution for the client. We do so, taking into consideration the client's preferences. Our research also studies selecting methods for the best overall service. This service not only considers the matching of functional factors provided by the web service's selecting process, but it is also accommodating by matching the information as defined by the client. This paper research can offer the best quality service preferred by any end-user. Again, this is done by utilizing web services that considers the user's non-functional factors identified by the web service's selecting process and also by extracting matching information.

• Convergence Security Journal
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• v.8 no.4
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• pp.105-113
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• 2008

Mobile computing environment is known to be quite difficult to provide user with a stable Quality of Service (QoS) due to vehicle mobility nature. In order to protect the inherent characteristics of wireless network such as low bandwidth and high transmission delay along with the vehicle's mobility, many works are conducted to apply caching and prefetching methods. This paper presents a novel prefetching technique which is based on owner's profile. It is the scheme with the vehicle velocity, the visit frequency and resident time of specific region for vehicle owner's past given period, and the user profile which has owner's personal inclination about a certain place. The proposed scheme shown relatively superior performance in terms of the utilization ratio of prefetched information and the failure ratio of information retrieval than the previous methods.