• Journal of Korea Multimedia Society
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• v.25 no.2
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• pp.325-334
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• 2022

Digital twin has the advantages of quality improvement and cost reduction, so it is widely applied to various industries. In this paper, a method to implement the major technologies of digital twin easily and quickly is presented. These include data management and relay servers, real-time monitoring applications including remote control interfaces, and direct connection protocols for video streaming. In addition, an algorithm for controlling a two-wheeled vehicle with a 2D interface is also proposed. The implemented system performs near real-time synchronization between the real environment and the virtual space. The delay time that occurs in remote control of the vehicle in the real environment was compared with the results of applying the proposed delay time reduction method. In addition, in the case of 2D interface-based control, an algorithm that can guarantee the user experience was implemented and applied to the actual environment and verified through experiments.

• Journal of KIISE:Computing Practices and Letters
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• v.15 no.7
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• pp.489-494
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• 2009

Since multimedia content is often independently encoded into multiple variations having diverse bandwidths, resolutions and compression formats, the same segment might be stored at different temporal positions within the variations. In this paper, we present a durable multimedia bookmark mechanism which provides a convenient way of switching to any variation before or during playback of the multimedia content, without experiencing temporal discontinuity or overlapping a portion of the content. We also present a new multimedia bookmark player with which users can manage a personal collection of bookmarks with an intuitive visual interface.

• Journal of Korea Multimedia Society
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• v.7 no.8
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• pp.1058-1065
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• 2004

Embedded system is widely used in various applications from simple monitor to a set-top box with CPU, memory and hard disk drives. Specially, embedded OS is ported in moveable or small machinery since it ordinarily transmits multimedia data. In this paper, we propose Null copy scheme on the embedded linux system for multimedia service, which can reduce memory copy overhead from user address space to kernel one, and vice versa. Since embedded system for networked multimedia service has low level computing power as well as memory, the Null copy scheme can provide more improved QoS. Our image transmission experiment results on embedded linux target board(CPU utilization an Deadline miss rates) installed a web camera have shown that the proposed scheme can increase fast response and lower CPU overhead.

• Journal of Korea Multimedia Society
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• v.6 no.3
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• pp.488-495
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• 2003

With the development of networks, multimedia communication has expanded its application field. From the remote control for household electric appliances to medicine, games, video conferencing and multimedia chatting, multimedia communication is being used in all parts of our lives. This multimedia communication requires the transmission of a lot of data at high speed. But if the transmission rate of the communication network exceeds the processing speed of being used in the high speed network environment, a bottleneck occurs in each node and deteriorates the performance of the network. This is the main reason for the slow speed of data transmission and packet loss. In this paper, considering the client's processing performance, reception performance was predicted and the way of flow control was shown. The computing performance of relevant Processor and its performance was estimated through the actual implementation.

• Journal of Information Processing Systems
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• v.7 no.2
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• pp.299-320
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• 2011

The overhead of processing fine-grain tasks on a grid induces the need for batch processing or task group deployment in order to minimise overall application turnaround time. When deciding the granularity of a batch, the processing requirements of each task should be considered as well as the utilisation constraints of the interconnecting network and the designated resources. However, the dynamic nature of a grid requires the batch size to be adaptable to the latest grid status. In this paper, we describe the policies and the specific techniques involved in the batch resizing process. We explain the nuts and bolts of these techniques in order to maximise the resulting benefits of batch processing. We conduct experiments to determine the nature of the policies and techniques in response to a real grid environment. The techniques are further investigated to highlight the important parameters for obtaining the appropriate task granularity for a grid resource.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.170-173
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• 2009

In this paper, we propose a fast intra prediction mode selection method in Scalable Video Coding(SVC) which is an emerging video coding standard as an extension of H.264/Advanced Video Coding(H.264/AVC). The proposed method decides a candidate intra prediction mode based on the characteristic of macroblock smoothness. Statistical analysis is applied to computing that smoothness in spatial enhancement layer. We also propose an early termination scheme for Intra_BL mode decision where the RD cost value of Intra_BL is utilized. Compared with JSVM software, our scheme can reduce about 55% of the computation complexity of intra prediction on average, while the performance degradation is negligible; For low QP values, the average PSNR loss is very negligible, equivalently the bit rate increases by 0.01%. For high QP values, the average PSNR loss is less than 0.01dB, which equals to 0.25% increase in bitrate on average.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.149-150
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• 2016

모바일 컴퓨팅의 발전은 모바일 디바이스에게 클라우드 컴퓨팅 기술 도입을 가져왔다. 모바일 클라우드 컴퓨팅은 워크스테이션 및 클러스터로 구축된 클라우드 컴퓨팅과 다르게 모바일 디바이스만을 가지고 자원 서비스를 제공한다. 모바일 클라우드는 모바일 디바이스의 저조한 하드웨어 성능과 산발적인 네트워크 연결을 가진다. 모바일 클라우드의 인프라 구성을 위해서는 모바일 디바이스의 연결 및 자원 통합이 매우 중요시 된다. 본 논문에서는 모바일 클라우드 컴퓨팅의 인프라 구축을 위해 연결된 모바일 디바이스의 자원 통합 및 지속적인 자원 서비스 관리를 제공하는 M-RIM(Mobile device - Resource Integration Management)을 제안한다. M-RIM은 모바일 디바이스의 성능 정보 메타데이터 기반 분산 자원을 통합하고 사용자에게 자원 서비스를 제공한다.

• Proceedings of the Korea Information Processing Society Conference
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• 2016.10a
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• pp.151-153
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• 2016

모바일 디바이스의 성능 발전에 따라 높은 연산 능력을 요구하는 어플리케이션이 증가하고 있다. 3D 프로세싱, 영상 인코팅, 벡터 이미지 처리 등 연산량이 많아 기존에 데스크탑 컴퓨터에서 처리하던 작업들이 모바일 디바이스로 이전되고 있다. 그러나 모바일 디바이스 하드웨어의 발전 속도와 상이하게 사용자의 모바일 디바이스 교체 주기는 발전 속도를 따라잡지 못하고 있다. 따라서 추가적인 비용부담 없이 모바일 디바이스의 연산 능력을 향상시키기 위해 Mobile Cloud Computing(MCC)의 필요성이 대두되고 있다. MCC는 다수의 모바일 디바이스 리소스를 통합 관리하고 자원 서비스를 제공함으로써 작업 처리 및 자원 고가용성등의 성능 향상이 가능하다. 본 연구에서는 MCC 인프라 구축 방법인 Mobile Resource Integration(MRI)와 MRI에 적용되는 오프로드 방법을 제안한다. 모바일 디바이스로만 구성된 MRI는 분산된 모바일 디바이스로 작업를 분할 전송 처리는 방법이다. 이를 통해 중거리 및 원거리 통신망 연결이 어려운 경우에 단일 모바일 디바이스의 작업 처리 대비 높은 향상 속도를 보인다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.6 no.1
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• pp.241-269
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• 2012

Wireless networks composed of multimedia-enabled resource-constrained sensor nodes have enriched a large set of monitoring sensing applications. In such communication scenario, however, new challenges in data transmission and energy-efficiency have arisen due to the stringent requirements of those sensor networks. Generally, congested nodes may deplete the energy of the active congested paths toward the sink and incur in undesired communication delay and packet dropping, while bit errors during transmission may negatively impact the end-to-end quality of the received data. Many approaches have been proposed to face congestion and provide reliable communications in wireless sensor networks, usually employing some transport protocol that address one or both of these issues. Nevertheless, due to the unique characteristics of multimedia-based wireless sensor networks, notably minimum bandwidth demand, bounded delay and reduced energy consumption requirement, communication protocols from traditional scalar wireless sensor networks are not suitable for multimedia sensor networks. In the last decade, such requirements have fostered research in adapting existing protocols or proposing new protocols from scratch. We survey the state of the art of transport protocols for wireless multimedia sensor networks, addressing the recent developments and proposed strategies for congestion control and loss recovery. Future research directions are also discussed, outlining the remaining challenges and promising investigation areas.

• The KIPS Transactions:PartC
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• v.13C no.2 s.105
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• pp.241-248
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• 2006

Mobile computing has such characteristics as portability, wireless network, mobility, etc. These characteristics cause various problems to mobile terminals like frequent disconnection, high error rate, and varying network status. These problems motivate us to develop an adaptive error control mechanism for supporting multimedia service in mobile computing environment. In this paper, we propose the Adaptive Error Control(AEC) scheme using client's buffer size and current error rate. After categorizing the status into four groups according to client's buffer size and current error rate, this scheme applies an appropriate error control scheme to each status. In this scheme, thresholds of buffer size and error rate are determined by the data transmission time, play rate and average VOP size, and by the probability of error for a sequence of packets. The performance of proposed scheme is evaluated by flaying MPEG-4 files on an experimental client/server environment, respectively. The results show that error correcting rate is similar to other schemes while the time for correcting error reduce a little. In addition, the size of data for correcting error is decreased by 23% compared with FEC and Hybrid FEC, respectively. Theses results demonstrate that the proposed scheme is more suitable in mobile computing environment with small bandwidth and varying environment than existing schemes.