• Journal of Korea Multimedia Society
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• v.18 no.6
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• pp.723-733
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• 2015

High availability is of utmost importance in real-time embedded systems. Temporary failures due to software or hardware faults should not result in a system crash. To achieve high availability, embedded systems typically use a combination of hardware and software techniques. A watchdog timer is a hardware component in embedded microprocessors that can be used to automatically reset the processor if software anomalies are detected. The embedded system relies on a single watchdog timer, however, can be permanently disabled if the timer is not properly configured, e.g. falling into an indefinite loop. STM32F4 provides two different types of watchdog timer in terms of timing accuracy and robustness. In this paper, we propose a hybrid approach, called long-tail watchdog timer, to utilize both timers to achieve self-reliance in embedded systems even though one of timers fails. Experimental results confirm that the proposed approach successfully handles various failure scenarios and present performance comparisons between single watchdog timer and hybrid approach in terms of configuration parameters of watchdog timers in STM32F4, counter value and window size.

• Journal of Korea Multimedia Society
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• v.8 no.9
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• pp.1282-1291
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• 2005

This paper presents the EVM(Embedded Virtual Machine) which enables the execution of dynamic applications loaded in the embedded systems such as Mobile Devices(mobile phone, PDA), Set-Top Box, and Digital TV using downloading techniques. To accomplish this goal, we defined a SIL-(Standard Intermediate Language) code, and implemented a Bytecode-to-SIL translator which enables the execution of programs written in java language in the EVM platform without JVM, and a MSIL--to-SIL- translator which enables for programs written in .NET language to be executed in the EVM platform without .NET platform. Also, we developed a EFF(Executable File Format) builder as an assembler which translates SIL codes into an executable file, *.evm, and implemented the EVM which reads the *.evm file and executes it. The virtual machine for embedded systems developed in this paper is the software technologies that enable the execution of applications or contents without changes to when the platforms change. In fact, the virtual machine suggested here is not only usable as a standard model for existing virtual machines but also aid in more efficient execution of applications loaded in the embedded systems such as Mobile Devices, Digital TV, and Set-Top Box.

• JSTS:Journal of Semiconductor Technology and Science
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• v.11 no.3
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• pp.207-220
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• 2011

Coarse-grained reconfigurable architecture (CGRA) based embedded systems aims to achieve high system performance with sufficient flexibility to map a variety of applications. However, the CGRA has been considered as prohibitive one due to its significant area/power overhead and performance bottleneck. In this work, I propose reconfigurable multi-array architecture to reduce power/area and enhance performance in configurable embedded systems. The CGRA-based embedded systems that consist of hierarchical configurable computing arrays with varying size and communication speed were examined for multimedia and other applications. Experimental results show that the proposed approach reduces on-chip area by 22%, execution time by up to 72% and reduces power consumption by up to 55% when compared with the conventional CGRA-based architectures.

• Journal of Korea Multimedia Society
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• v.13 no.5
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• pp.710-721
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• 2010

Recently, for the advancement of embedded technology about mobile device, a new kind of service, mash-up is appeared. It is service or application combining multimedia content making tool or device and web-GIS(geographic information system) service in the mobile environment. This service can be ease to use for casual user and can apply in various ways. So, It is served in web 2.0 environment actively. But, in the mashup service, because generated multimedia contents linked with web map are new type of multimedia contents which include user's migration routes in the space such as GPS coordinates. Thus, there are no protection ways for intellectual property created by GIS web-map service users and user's privacy. In this paper, we proposed a location and user information hiding scheme for GIS web-map service. This scheme embeds location and user information into a picture that is taken by camera module on the mobile phone. It is not only protecting way for user's privacy but is also tracing way against illegal photographer who is peeping person through hidden camera. And than, we also realized proposed scheme on the mobile smart phone. For minimizing margin of error about location coordinate value against contents manipulating attacks, GPS information is embedded into chrominance signal of contents considering weight of each digit about binary type of GPS coordinate value. And for tracing illegal photographer, user information such as serial number of mobile phone, phone number and photographing date is embedded into frequency spectrum of contents luminance signal. In the experimental results, we confirmed that the error of extracted information against various image processing attacks is within reliable tolerance. And after file format translation attack, we extracted embedded information from the attacked contents without no damage. Using similarity between extracted one and original templete, we also extracted whole information from damaged chrominance signal of contents by various image processing attacks.

• Journal of Korea Multimedia Society
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• v.14 no.7
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• pp.940-948
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• 2011

In this paper, we design and implement a task scheduler that considers real-time and fault tolerance in embedded system with a single processor. We propose a method how it can meet the deadlines of periodic tasks using RMS and complete the execution of aperiodic tasks by calculating surplus times from a periodic task set. And we describe a method how to recover of a transient fault task by managing backup time. We propose an important level of periodic tasks that can control the response time of periodic and aperiodic tasks. Finally, we analyse and evaluate the proposed methods by simulation.

• Journal of Korea Multimedia Society
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• v.9 no.4
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• pp.401-413
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• 2006

We propose video management system based on MPEG-7 for mobile device(MVMS). Most of existing MPEG-7 applications manage MPEG-7 document based on file system in the desktop environment. To contrast them, because the MVMS manages only necessary information using embedded database system for MPEG-7 documents in mobile devices, it can use efficiently lack of the resource in mobile device environment. MVMS supports key image extraction and MPEG-7 document edition function. Moreover, this is possible search and management of multi document because of MVMS manage MPEG-7 data through embedded DB.

• Journal of Korea Multimedia Society
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• v.13 no.9
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• pp.1322-1328
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• 2010

Recently, keyword spotting system is greatly in the limelight as UI(User Interface) technology of ubiquitous home network system. Keyword spotting system is vulnerable to non-stationary noises such as TV, radio, dialogue. Especially, speech recognition rate goes down drastically under the embedded DSP(Digital Signal Processor) environments because it is relatively low in the computational capability to process input speech in real-time. In this paper, we propose a new keyword spotting system using the call-command method, which is consisted of small number of recognition networks. We select the call-command such as 'narae', 'home manager' and compose the small network as a token which is consisted of silence with the noise and call commands to carry the real-time recognition continuously for input speeches.

• Journal of Korea Multimedia Society
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• v.12 no.2
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• pp.165-177
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• 2009

Embedded database systems (EDBMS) based on NAND flash memories are widely adopted for logging data on sensor nodes. Since write and erase operations of a flash memory are time consuming compared to read operations and wear memory cells, it is important to reduce these operations to enhance the EDBMS performance and to extend the memory life. In this paper, we propose a delayed write scheme to archive this goal. Proposed scheme stores updated parts of database pages into delayed write records to reduce the database page writes. By doing that, it decreases write and erase operations on a flash memory. Therefore, the proposed scheme enhances the logging performance of a write-intensive EDBMS on a sensor node and extends the flash memory life.

• Journal of Korea Multimedia Society
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• v.10 no.7
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• pp.882-892
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• 2007

In this paper, we propose a mechanism for both scheduling the hybrid-task set which consists of periodic and aperiodic tasks and recovering tasks with transient faults on the level of the operating system. Existing embedded operating systems would not provide the scheduling of both periodic and aperiodic tasks. Also because of not supporting the recovery of task failures, they can not prevent system failure from transient task faults. Proposed method, on the level of operating system, is able to not only meet the deadlines of all periodic tasks but also complete the execution of aperiodic tasks. In addition, it is able to prevent the system failure from transient task faults by recovering the task faults.

• Journal of Korea Multimedia Society
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• v.20 no.6
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• pp.893-910
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• 2017

In this paper, we propose a simple online multiple object (human) tracking method, LKDeep (Lucas-Kanade feature and Detection based Simple Online Multiple Object Tracker), which can run in fast online enough on CPU core only with acceptable tracking performance for embedded surveillance purpose. The proposed LKDeep is a pragmatic hybrid approach which tracks multiple objects (humans) mainly based on LK features but is compensated by detection on periodic times or on necessity times. Compared to other state-of-the-art multiple object tracking methods based on 'Tracking-By-Detection (TBD)' approach, the proposed LKDeep is faster since it does not have to detect object on every frame and it utilizes simple association rule, but it shows a good object tracking performance. Through experiments in comparison with other multiple object tracking (MOT) methods using the public DPM detector among online state-of-the-art MOT methods reported in MOT challenge [1], it is shown that the proposed simple online MOT method, LKDeep runs faster but with good tracking performance for surveillance purpose. It is further observed through single object tracking (SOT) visual tracker benchmark experiment [2] that LKDeep with an optimized deep learning detector can run in online fast with comparable tracking performance to other state-of-the-art SOT methods.