• 한국정보과학회논문지:정보통신
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• 제29권2호
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• pp.141-155
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• 2002

본 논문에서는 기지국과 단말기간의 전파지연이 비교적 짧은 마이크로셀 환경의 패킷 CDMA망에서 음성과 데이타를 통합 서비스하기 위한 MAC 프로토콜을 제안한다. 제안한 프로토콜을 위한 시스템의 상향링크 채널은 프레임을 구성하는 타임 슬롯과 각 슬롯별 확산코드에 의하여 제공된다. 지연에 민감한 음성 트래픽에 더 높은 우선순위를 부여하여, 음성 트래픽인 경우에는 발음구간 동안 임의의 확산코드를 예약하여 서비스된다. 반면, 데이타 트래픽은 매 패킷이 발생할 때마다 기지국으로부터 수신한 현재 슬롯의 예약상태 정보를 기반으로 서비스된다. 성능분석의 결과, 본 논문에서 제안한 기법은 음성과 데이타 패킷간의 충돌이 전혀 발생하지 않으므로 주어진 패킷 누락률 범위 내에서 수용 가능한 최대 음성 단말기 수를 증가시킬 수 있었다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제7권1호
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• pp.56-67
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• 2013

Because H.264/SVC can meet the needs of different networks and user terminals, it has become more and more popular. In this paper, we focus on the spatial resolution scalability of H.264/SVC and propose a blind video watermarking algorithm for the copyright protection of H.264/SVC coded video. The watermark embedding occurs before the H.264/SVC encoding, and only the original enhancement layer sequence is watermarked. However, because the watermark is embedded into the average matrix of each macro block, it can be detected in both the enhancement layer and base layer after downsampling, video encoding, and video decoding. The proposed algorithm is examined using JSVM, and experiment results show that is robust to H.264/SVC coding and has little influence on video quality.

• Journal of Power Electronics
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• 제14권6호
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• pp.1233-1242
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• 2014

A new inverter topology for single-phase photovoltaic (PV) systems is proposed in this study. The proposed inverter offers a four-level voltage in its output terminals. This feature results in easier filtering in comparison with other conventional two-level or three-level inverters. In addition, the proposed four-level inverter (PFLI) has a transformer-less topology, which decreases the size, weight, and cost of the entire system and increases the overall efficiency of the system. Although the inverter is transformer-less, it produces a negligible leakage ground current (LGC), which makes this inverter suitable for PV grid-connected applications. The performance of the proposed inverter is compared with that of a four-level neutral point clamped inverter (FLNPCI). Theoretical analysis and computer simulations verify that the PFLI topology is superior to FLNPCI in terms of efficiency and suitability for use in PV transformer-less systems.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2002년도 ITC-CSCC -2
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• pp.1090-1093
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• 2002

Location management schemes dealing with location information of moving terminals play an important role in the personal communications systems (PCS). Since the location management involves heavy signaling traffics to update the location information, reducing the location update cost becomes a critical research issue. This paper proposes a location management scheme which reduces the location update cost by employing the hierarchical structure in PCS environment. The paper also develops analytical models to evaluate the performance of the proposed scheme. The results obtained from the performance evaluation shows that the proposed scheme outperforms the conventional schemes in terms of the location update rates. Also, the difference in the performance becomes larger as the size of the location area (LA) becomes smaller and as the residual time of the mobile user becomes smaller.

• 한국컴퓨터정보학회논문지
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• 제22권8호
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• pp.25-32
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• 2017

In this paper we propose a resource management method which enables to guarantee the quality of experience (QoE) for handover in the overlaid macro-femtocell networks. How to cope with the resource demand of handover calls is necessary to efficiently support the movement of mobile terminals, the QoE degradation or the load control. We attempt to satisfy the QoE requirements of users and maximize the capacity of the system at the same time. In order to achieve this goal, this scheme divides the shared resources into two part for the movement of MT and QoE degradation, and allocates those resources with the competition between four types of handovers. Simulation results show that our scheme provides better performances than the conventional one with respect to the outage probability, data transmission throughput.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2011년도 춘계학술대회
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• pp.216-217
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• 2011

The problem of automated stacking cranes (ASC) dispatching in container terminals is addressed in this paper. We propose a heuristic-based ASC dispatching approach which adopts multi-criteria decision strategy. By aggregating different criteria the proposed strategy can consider multiple aspects of the dispatching situation and make robust decision in various situations. A multi-objective evolutionary algorithm (MOEA) is adopted to tune the weights associated to each criteria to minimize both the quay crane delay and external truck delay. The proposed approach is validated by comparison with different dispatching heuristics and simulation results obtained confirms its effectiveness.

• 한국컴퓨터정보학회논문지
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• 제21권1호
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• pp.49-57
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• 2016

In this paper we propose the resource allocation scheme for the overlaid macro-femtocell networks, which considers the type of handovers such as the inter-macrocell, macrocell-to-femtocell, femtocell-to-macrocell, or inter-femtocell in order to guarantee Quality of Service (QoS) and expand the accommodation capacity. Our proposed scheme takes into account the movement of mobile terminals, the QoS degradation, or the load control which trigger handovers in the overlaid networks, before it allocates resources dynamically. Moreover it considers QoS requirements of realtime or non-realtime mobile multimedia services such as video communication, Video on Demand (VoD) and dataa services. Simulation results show that our scheme provides better performances than the conventional one with respect to the outage probability, data transmission throughput and handover failure rate.

• Journal of Information Processing Systems
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• 제1권1호
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• pp.1-8
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• 2005

Embedded systems are used in many fields such as home appliances, terminals, controls, communications, etc. So, to manage, control, and test these embedded systems, monitoring programs have been developed variously. In this paper, to overcome the characteristic faults of embedded systems which have resource restrictions, we implemented a development environment based on NFS and designed a monitoring tool that can evaluate and analyze kernel performance in embedded equipment by using LTT(Linux Trace Toolkit). Also, we designed a method to show monitoring data collected by using a monitoring tool, called MONETA 2.0, through the web-page.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2000년도 제13회 춘계학술대회 및 임시총회 학술발표 논문집
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• pp.414-418
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• 2000

CDMA 단말기의 DBMS는 단말기를 운영하는데 필요한 시스템 및 가입자의 정보를 관리하기 위한 소프트웨어로서 서비스 제공에 있어서의 실시간성과 높은 신뢰성, 그리고 효과적인 Fault Tolerance 및 고장으로부터의 신속한 회복 기능을 제공하여야 한다. 이를 위해 이동통신용 단말기에서는 실시간 운영체제를 기반으로 하는 Non-Volatile 메모리인 EEPROM에 저장하여 관리하는 방법을 채택하고 있다. CDMA 단말기에서 사용하는 MSM(Mobile Station Modem)과 단말기 소프트웨어는 운영체제 환경하에서 동작하는데 기능 중심으로 여러 개의 Task들을 설계하고 이들이 필요한 기능들을 수행하도록 하고 있다. 본 논문에서는 CDMA 단말기 소프트웨어의 여러 Task 중에서 EEPROM과 관련하여 데이터베이스 시스템 역할을 수행하는 NVDB Task(Non-Volatile Database Task)의 기능과 구조를 다룬다.

• 한국정보처리학회:학술대회논문집
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• 한국정보처리학회 2000년도 제13회 춘계학술대회 및 임시총회 학술발표 논문집
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• pp.465-469
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• 2000

CDMA 단말기의 DBMS는 단말기를 운영하는데 필요한 시스템 및 가입자의 정보를 관리하기 위한 소프트웨어로서 서비스 제공에 있어서의 실시간성과 높은 신뢰성, 그리고 효과적인 Fault Tolerance 및 고장으로부터의 신속한 회복 기능을 제공하여야 한다. 이를 위해 이동통신용 단말기에서는 실시간 운영체제를 기반으로 하는 Non-Volatile 메모리인 EEPROM에 저장하여 관리하는 방법을 채택하고 있다. CDMA 단말기에서 사용하는 MSM(Mobile Station Modem)과 단말기 소프트웨어는 운영체제 환경하에서 동작하는데 기능 중심으로 여러 개의 Task들을 설계하고 이들이 필요한 기능들을 수행하도록 하고 있다. 본 논문에서는 CDMA 단말기 소프트웨어의 여러 Task 중에서 EEPROM과 관련하여 데이터베이스 시스템 역할을 수행하는 NVDB Task(Non-Volatile Database Task)의 기능과 구조를 다룬다.