• Journal of the Korea Society of Computer and Information
• /
• v.14 no.1
• /
• pp.57-64
• /
• 2009

Recently virtualization has been one of the most popular research topics in system software area. While there already exist many commercial virtualization products for general-purpose computer system, little efforts are made to virtualize embedded system. In this paper, we design and implement a virtual machine monitor which divides each physical hardware resource of a embedded system into logical ones and reorganizes them into many virtual machines, which result in running several real-time operating systems concurrently on a single embedded system. We measure various performance metrics of the virtual machine monitor developed on a real embedded system. The results of the study show that our virtual machine monitor has enough potentiality of its application to real-world embedded systems.

• Journal of the Korea Society of Computer and Information
• /
• v.27 no.5
• /
• pp.11-19
• /
• 2022

In this paper, we propose a fault tolerant embedded system using memory redundancy on the full-virtualization based virtual machine monitor. The proposed virtual machine monitor first virtualizes main memory of embedded system utilizing efficient shadow page table scheme so that the embedded system runs as a virtual machine on the virtual machine monitor. The virtual machine monitor makes the backup of the embedded system run as another virtual machine by copying memory contents of the embedded system into memory space of backup system according to predefined schedules. When an error occurs in the target virtual machine, the corresponding standby virtual machine takes the role of target virtual machine and continues its operation. Performance evaluation studies show that such backups and switches of virtual machines are performed with minor performance degradation.

• Journal of the Korea Society of Computer and Information
• /
• v.22 no.6
• /
• pp.1-8
• /
• 2017

In this paper, we propose a fault tolerance technique which enables embedded systems to run without interruption while its operating system and tasks fail. In order to improve reliability, the proposed scheme makes an embedded system run as a virtual machine on virtual machine monitor. It also prepares a contingency virtual machine at which periodical backups of the embedded system are saved. When an error occurs in the main virtual machine, the corresponding standby virtual machine takes a role of the main virtual machine and continues its operation. Especially such backups and switches of virtual machines are performed with minor performance degradation by manipulating page table entries in virtual machine monitor. By conducting performance evaluation studies, we show that the proposed scheme makes embedded system robust against errors while it does not degrade the performance of the system significantly.

• Journal of the Korea Society of Computer and Information
• /
• v.17 no.9
• /
• pp.127-138
• /
• 2012

In this paper, we present a tool (named VMBootFailMonitor) to detect and analyze a failure of a VM boot creation caused by faults on virtual disks of a Xen-based VM. Also, we presents an architecture and detail analysis process of the virtual disk faults in our tool. Especially, VMBootFailMonitor provides a causual analysis result for a case of VM creation failure based on three modules which performs virtual disk analysis, virtualized system analysis and system log analysis. We also support a comparison result between boot times of normal VMs and fault detection times of VM creation based on abnormal virtual disks. At result, our tool detects VM boot failures (3~6 seconds) within normal VM boot times (8~16 seconds).

• Proceedings of the Korean Institute of Intelligent Systems Conference
• /
• 2003.09a
• /
• pp.70-73
• /
• 2003

This paper proposes a movement instruction system using virtual environment. This system consists of a monitor, cameras, ana a PC. A learner is coached by a virtual instructor that is displayed in virtual environment as 3 dimensional computer graphics on the monitor. Virtual instructor shows sample movement and suggests mistakes of learner's movement by recognizing movement of learner's movement from the picture that cameras capture. To improve the robust characteristic of information from cameras, the system enables to select optimum inputs from cameras based on learner's movement It implemented by Fuzzy associative inference system Fuzzy associative inference system is implemented by bi-directional associative memory and fuzzy rules. It is suitable to convert obscure information into clear. We implement and evaluate the movement instruction system

• Science of Emotion and Sensibility
• /
• v.19 no.3
• /
• pp.71-80
• /
• 2016

The purpose of this study was to examine the effects of display on time on tasks and virtual presence in the immersive virtual reality. Head mounted display (HMD) and monitor conditions were compared when the participants were asked to complete navigation tasks in a virtual classroom. Time on tasks and virtual presence were measured. Three factors of the virtual presence were applied as dependent variables such as 1) spatial presence, 2) involvement, and 3) realness. The results showed that HMD condition took longer time to finish tasks than monitor conditions. HMD condition showed significantly higher perception from all of the virtual presence factors. Interestingly, there was a significant interaction effect between the display conditions and presence factors. The relationship between display types and virtual presence factors were discussed for future study.

• Korean Institute of Interior Design Journal
• /
• v.17 no.5
• /
• pp.166-174
• /
• 2008

As the use of virtual environment for decision-making interior or architectural design has been increasingly broaden, the choice of media form-physical, objective properties of a display medium-became and important issue to take into consideration. This research deals with the effects and differences between two types of media for a virtual environment; wall projection screen(120") and PC monitor(17"). In addition, efficient adoption of the two media forms was also proposed in this research. A total of 90 subjects participated in pre-designed three experimental groups(A group: experiment with a wall projection screen, B group: experiment with PC monitor, C group: both) and answer the seating preferences, the presence inventory, and the decision confidence using a simulated virtual restaurant environment. The results are as follows: (1) seating preferences for the tables located in frequent traffic area and near other spaces such as restroom and th kitchen are significantly different by the media form. While there is no significant difference found in seating preferences for most tables except high traffic areas near entrances between the two media. This result demonstrates the effects of media type or screen size on user perception for the areas near structural or interior design elements. (2) The presence measure in this research consist of in this research consist of four factors: 'spatial presence,' 'object presence,' 'positive effects,' and 'the factor of negative effects. 'The mean values of the items involving engagement or interaction in the spatial presence factor and the object presence factor are significantly different by the media form. A higher sense of presence of presence was observed in the wall projection screen. (3) PC monitor condition was shown to provide a higher level of decision confidence. Based on the research finding, conclusions and implications are discussed.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.12 no.4
• /
• pp.14-19
• /
• 1998

The purpose of our study is to develop tool kits which give us inexpensive simulation method. We develop a Programmable Logic Controller (PLC) program module with which we can edit and monitor PLC program, a virtual PLC (VPLC) system and simulation equipment. The PLC and simulation equipment are interlinked each other and controlled by the PLC program in real time. So, e can get effect as actural operation. Using our new tool kits we don't have to prepare PLC and machine, because we can configure PLC system and see the response of virtual machine n monitor. For validity of the developed program, we make experiments for the PLC program of elevator and automatic materials weighting system. The experimental results show that the virtual machine (VM) operates properly by the PLC control program.

• The Journal of the Korea Contents Association
• /
• v.20 no.9
• /
• pp.531-540
• /
• 2020

Objectives: This study aimed to investigate the effects of a 4-weeks intervention using a monitor-based virtual reality game intervention(VRI) on the cognitive function and activities of daily living of individuals with acute stroke. Methods: For this study, 19 individuals with acute stroke were recruited. To compare the effectiveness of the VRI and the computer based cognitive intervention(CBCI), Each of the two groups were provided different interventions a 30 minutes a day, 5 times per week for 4 weeks, and to measure the effects of the intervention, the TMT A&B, DST, RKMT and K-MBI were performed before and after interventions. Results: Both the VRI and the CBCI were found to have significantly improved the cognitive function and activities of daily living, and the difference in change compared between groups showed that the effectiveness of the VRI was significantly higher. Conclusion: Based on the findings of this study, the monitor-based VRI is anticipated to prove useful as an effective intervention for the cognitive function and activities of daily living of stroke patients. Furthermore, the utility of monitor-based VRI is likely to be high in clinical occupational therapy.

• Proceedings of the IEEK Conference
• /
• 2005.11a
• /
• pp.19-22
• /
• 2005

In order to achieve high capacity and reliable link quality in user communication, this paper proposes a new concept of virtual cell: the Dual Virtual Cell(DVC), and DVC employment strategy based on DWCS. The proposed system uses two kinds of virtual cell. One is the AVC(Active Virtual Cell) which exists for actual traffic and the other is the CVC(Candidate Virtual Cell) which contains a set of candidate antennas to protect user's link quality from performance degradation or interruption. And also this system aims to reduce MT's overloads and acheive a prompt link change successfuly by introducing DVC structure which makes it possible for network to monitor real-time channel and to conrol communication links. The proposed system constructs DVC by using antenna selection method and improves frame error performance with employing Space-Time Trellis Code(STTC).