• Journal of Advanced Navigation Technology
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• v.19 no.1
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• pp.85-90
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• 2015

In this paper, a novel Internet-of-things (IoT) based telecare system is proposed to provide high-quality care services to silver generations. It consists of various sensor nodes including activity sensors, wearable emergency pagers, emergency telephone as a home gateway, and a server as a telecare service platform. Especially, an activity index as a qualification method is presented to analyze the activities of daily living. By using the activity index, the daily/weekly/monthly activity information can be obtained, from which we infer the activity pattern, notice the abrupt change of the activity, and take appropriate actions in abnormal situations.

• Journal of Broadcast Engineering
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• v.18 no.2
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• pp.185-195
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• 2013

In this paper, we propose a video summarization technique on a smartphone, based on spatiotemporal saliency. The proposed technique detects scene changes by computing the difference of the color histogram, which is robust to camera and object motion. Then the similarity between adjacent frames, face region, and frame saliency are computed to analyze the spatiotemporal saliency in a video clip. Over-segmented hierarchical tree is created using scene changes and is updated iteratively using mergence and maintenance energies computed during the analysis procedure. In the updated hierarchical tree, segmented frames are extracted by applying a greedy algorithm on the node with high saliency when it satisfies the reduction ratio and the minimum interval requested by the user. Experimental result shows that the proposed method summaries a 2 minute-length video in about 10 seconds on a commercial smartphone. The summarization quality is superior to the commercial video editing software, Muvee.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12B
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• pp.831-837
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• 2005

Personal general purpose computer(PC) has been evolved from desktop to portable mobile device such as tablet PC and PDA. Technology innovation on semiconductor have made it possible to package a reasonably Powerful Processor and memory subsystem with advanced input/output devices. At last these subsystems are miniaturized into wearable system. Wearable computer has recently gained attention as the post PC in the ubiquitous environment. Wearable computing becomes more and more feasible and receives growing attention throughout industry and the consumer marketplaces. This paper proposed and developed WPS that has multimedia features and network features as a wearable embedded platform. We explain the form, overall architecture, functions and user applications of this WPS. This paper also discusses the form of next generation computer platform with intuitive user interfaces and well designed applications in the future.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2007.10a
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• pp.437-440
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• 2007

Recently embedded system developed a lot. Physically, embedded systems range from portable devices such as digital watches and MP3 players, to large stationary installations like traffic lights, factory controllers, or the systems controlling nuclear power plants. This paper focuses on implementation of portable device which is applicable to the child-kidnap or missing child prevention system in residential area or public area. To be specific, this device is to transmit video data which comes from the camera in the device into the host PC via WLAN. Embedded hardware platform consists of s3c2440 with ARM9 core, WindowsCE OS and other sensors. OS enables the platform to do multitasking jobs which are handling GPS data, taking video, capturing audio via microphone in the device and transfer all kind of realtime data to the host PC.

• Journal of KIISE:Computing Practices and Letters
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• v.16 no.6
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• pp.637-647
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• 2010

Recent embedded systems are being more complicated due to their hierarchical software architecture including operating systems. The performance of such complicated software architecture could not be well analyzed through separate analysis of each software layer; the combined effect and the interactions among the whole software layers should be considered. In this paper, we show the design and implementation of a performance analysis framework that enables hierarchical analysis of performance of Linux-based embedded systems considering interactions among the software layers. By using the proposed framework, we can obtain useful run-time information about a hierarchical software structure which usually consists of user-defined function layer, library function layer, system call layer, and kernel events layer. Experimental results reveal that the proposed framework could accurately identify the performance bottlenecks with the corresponding software layers during executions of target applications through the accompanying sub-steps of the analysis: the actual execution paths, the execution time of each observed event in each software layer, and the control flows across the software layers.

• Journal of KIISE:Computer Systems and Theory
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• v.33 no.9
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• pp.626-633
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• 2006

The wireless sensor networks are sensing, computing and communication infrastructures that allow us to monitor, instrument, observe, and respond to phenomena in the harsh environment. Sensor operating systems that run on tiny sensor nodes are the key to the performance of the distributed computing environment for the wireless sensor networks. Therefore, sensor operating systems should be able to operate efficiently in terms of energy consumption and resource management. In this paper, we present an efficient memory allocation scheme to improve the time and space efficiency of memory management for the sensor operating systems. Our experimental results show that the proposed scheme performs efficiently in both time and space compared with existing memory allocation mechanisms.

• Science of Emotion and Sensibility
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• v.6 no.1
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• pp.11-16
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• 2003

In this study, we examined the evaluation of virtual Reality (VR) according to the use of motion platform. We recorded electrogastrogram, skin conductance, blood volume, skin temperature, heart rate, and the frequency of eyeblink before, during, after virtual navigation in 33 subjects. We used simulator sickness questionnaire, presence questionnaire , and self-report to evaluate cybersickness and presence in VR system. All subjects experienced VR two times in Motion platform condition and non-Motion platform condition at two-week intervals. Presence score of motion platform condition was greater than non-motion platform condition. The frequency and severity of cybersickness were significantly reduced in motion platform condition than non-motion platform condition. These results suggest that the use of motion platform that synchronizes visual presentation provides higher presence and reduces cybersickness.

• Proceedings of the KAIS Fall Conference
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• 2006.05a
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• pp.517-521
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• 2006

네트워크 가상현실 시스템은 먼 거리에 떨어진 사용자들 사이에 일관성 있는 가상 세계를 제공하며, 군사, 오락, 건축 등 여러 부분에 응용되고 있다. 본 논문에서는 그 동안 고성능 그래픽 워크스테이션 환경에서 중심적으로 연구되어 왔던 네트워크 가상현실 시스템을 가장 보편적인 플랫폼인 네트워크 환경에서 구현할 때 생기는 3차원 그래픽 처리 성능의 문제 등과 같은 이에 대한 해결책들을 제시하고 미로 환경과 지형 환경에 근거한 가상 세계를 응용 실험 대상으로 삼아 성능을 분석하였다. 실시간으로 상호 작용하는 어플리케이션은 성능을 유지하면서 모든 참가자들에게 동일한 뷰를 보여주는 것이 중요하다. 동일한 뷰를 제공하기 위해 참가자들이 전송하는 이벤트마다 재생 지연 시간을 설정하고, 수신한 이벤트에 대해서는 예정 재생 시각까지 버퍼에 저장하여 모든 참가자들이 동시에 이벤트를 실행하도록 하는 기법이 제안되어 왔다. 그러나 네트워크 트래픽이 동적으로 변하므로 네트워크 상에서 발생하는 전송 지연 시간도 동적으로 변화한다. 그러므로 고정된 재생 지연 시간을 사용할 경우, 네트워크 트래픽 감소에 따라 상호 작용 성능을 향상시킬 수 있는 기회를 상실하게 되고, 네트워크 트래픽 증가에 따라 이벤트 손실률이 크게 증가하게 되어 참가자들 간에 일치하지 않는 뷰를 초래하게 된다. 네트워크 트래픽이 적어서 전송 지연 시간이 짧을 경우 짧은 재생 지연 시간을 적용하여 상호작용 성능을 높여주고, 트래픽이 많은 경우에는 재생 지연 시간을 늘림으로써 상호 작용 성능을 해치지 않는 범위에서 이벤트 손실률을 줄인다. 실험을 통하여 제안하는 기법의 성능을 평가하였으며 그 결과 본 동기화 기법이 고부하(heavily loaded) 네트워크 상태가 지속되는 동안 기존 기법에 비해 참가자들에게 일치된 뷰를 제공할 수 있고, 저부하(lightly loaded) 네트워크 상태에서는 상호 작용 성능을 향상시킬 수 있다는 것을 확인하였다.

• Journal of KIISE:Information Networking
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• v.29 no.6
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• pp.613-624
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• 2002

Within the past decade, TCP/IP network environment has been explosively widespread all over the world. As the internet and the WWW expand their boundaries, the network traffic caused by data transfers over the internet has also increased. In this paper, we present the design and implementation of a WebTraMAS (Web-based Traffic Monitoring and Analysis System) which can resolve the shortcomings of current management approaches, particularly on the network traffic monitoring and analysis. The WebTraMAS presented in this paper performs the network management activities based on the parameters related to the MIB-II of SNMP and the parameters related to the QoS such as network performance and fault. The proposed WebTraMAS, implemented using the WWW technology, is able for the network manager to manage the network easily and platform independently with the performance analysis of internet traffic.

• Journal of KIISE
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• v.43 no.2
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• pp.152-162
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• 2016

Most traditional garbage collectors commonly use the language level metadata, which is designed for pointer type searching. However, because it is difficult to use this metadata in non-volatile memory allocation platforms, a new garbage collection technique is essential for non-volatile memory utilization. In this paper, we design new metadata for managing information regarding non-volatile memory allocation called "Allocation Tree". This metadata is comprised of tree data structure for fast information lookup and a node that holds an allocation address and an object ID pair in key-value form. The Garbage Collector starts collecting when there are insufficient non-volatile memory spaces, and it compares user data and the allocation tree for garbage detection. We develop this algorithm in a persistent heap based non-volatile memory allocation platform called "HEAPO" for demonstration.