• Journal of Digital Contents Society
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• v.18 no.1
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• pp.167-173
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• 2017

As the increasing use of the cloud computing, virtualization technology have been combined and applied a variety of requirements. Cloud computing has the advantage that the support computing resource by a flexible and scalable to users as they want and it utilized in a variety of distributed computing. To do this, it is especially important to ensure the stability of the cloud computing. In this paper, we analyzed a variety of component measurement using open-source tools for ensuring the performance of the system on the education system to build cloud testbed environment. And we extract the performance that may affect the virtualization environment from processor, memory, cache, network, etc on each of the host machine(Host Machine) and a virtual machine (Virtual Machine). Using this result, we can clearly grasp the state of the system and also it is possible to quickly diagnose the problem. Furthermore, the cloud computing can be guaranteed the SLA(Service Level Agreement).

• Proceedings of the Korea Society for Simulation Conference
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• 2005.11a
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• pp.102-107
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• 2005

PMS(Plant Monitoring System) for simulation is the program for training that users such as instructor, operator, and supervisor can operate the plant virtually. Presented in this paper, are some lessons learned from implementation of PMS for simulation. First, this PMS fer simulation is based on LINUX instead of UNIX. These two OS(Operating System) have different platform and compiler version on it, so debugging needs to be done about variable defining part. Second, In LINUX system, the size of shared memory and message queue is already designated as a default value that user has to set up and use the RTAP DB. Third, to decrease the dummy data size, it has to be changed into binary formation. Lastly, PMS software for simulation provides several environments according to the command, so considered should be status monitoring, alarm, system organization, point and group monitoring, history storage and searching function.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2021.05a
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• pp.308-311
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• 2021

This paper describes the development of a functional game for preventing dementia for the elderly based on virtual reality. The game was developed using the Unity 3D engine to create a fishing spot, a virtual reality space. In consideration of the fact that the object of the game is an elderly person relatively unfamiliar with the virtual reality, the number of operation buttons is minimized and the sense of resistance and fatigue are reduced by an intuitive game configuration. In addition, the game was designed to give people a sense of accomplishment with a score system after the game, and to encourage them to participate in the game Overall, the developed game consists of main, interface, stage, score, TTS, tutorials, and ending credit. Each category stage is divided into three stages and realized in one integrated environment, and VRHMD can be used to games that enhance memory, attention, and judgment.

• KIISE Transactions on Computing Practices
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• v.24 no.3
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• pp.129-137
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• 2018

NVMe(Non-Volatile Memory Express) SSD(Solid State Drive) is a high-performance storage that makes use of flash memory as a storage cell, PCIe as an interface and NVMe as a protocol on the interface. It supports multiple I/O queues which makes it feasible to process parallel-I/Os on multi-core environments and to provide higher bandwidth than SATA SSDs. Hence, NVMe SSD is considered as a next generation-storage for data-center and cloud computing system. However, in the virtualization system, the performance of NVMe SSD is not fully utilized due to the bottleneck of the software I/O stack. Especially, when it uses I/O stack of the hypervisor or the host operating system like Xen and KVM, I/O performance degrades seriously due to doubled-I/O stack between host and virtual machine. In this paper, we propose a new I/O engine, called Direct-AIO (Direct-Asynchronous I/O) engine, that can access NVMe SSD directly for I/O performance improvements on QEMU emulator. We develop our proposed I/O engine and analyze I/O performance differences between the existed I/O engine and Direct-AIO engine.

• The KIPS Transactions:PartD
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• v.16D no.4
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• pp.507-516
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• 2009

In stream data processing system, generally the interval queries are in advance registered in the system. When a data is input to the system continuously, for realtime processing, a query indexing method is used to quickly search queries. Thus, a main memory-based query index with a small storage cost and a fast search time is needed for searching queries. In this paper, we propose a LVC-based(Limited Virtual Construct-based) query index method using a hashing to meet the both needs. In LVC-based query index, we divide the range of a stream into limited virtual construct, or LVC. We map each interval query to its corresponding LVC and the query ID is stored on each LVC. We have compared with the CEI-based query indexing method through the simulation experiment. When the range of values of input stream is broad and there are many short interval queries, the LVC-based indexing method have shown the performance enhancement for the storage cost and search time.

• Journal of The Korean Association of Information Education
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• v.3 no.1
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• pp.86-93
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• 1999

In this paper, we have designed and implemented that PC management system has the function of monitoring and controlling system management MIB defined for PC management using SNMP in PC room. System management MIB consists of monitoring MIB for system and processor information and controlling MIB for backup and restoration. For this, we have added new defined MIB variables to standard MIB and displayed system information, processor information, backup and restoration information of managed PC. And the structure between management system and managed system is shown and process of system information, processor information, backup and restoration of managed PC is illustrated. On real environmental, by monitoring window version, CPU type, system memory and virtual memory and performing backup and restoration of managed PC, actual operation is tested. Management system gathers system information and processor information from managed system and performs backup and restoration for recovering fault of managed system. Hence PC managers can operate and manage many PCs on LAN, efficiently.

• Journal of Korean Society of Archives and Records Management
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• v.16 no.1
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• pp.121-150
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• 2016

This paper reports the evaluation of six open-source software systems for participatory digital archives. This is an effort to create a digital platform for the social memory of No Gun Ri, which was first recognized in 1999 as a civilian massacre. The process of how it was reported and investigated is critical to understanding this brutal incident. In addition, the course of its cultural recovery has witnessed the reconstruction of the No Gun Ri memory. Thus, it is important to embrace the social memory around the massacre in these archives. In consideration of a virtual space for memory, this study takes the form of participatory archives to provide a mechanism in which anyone can share their memories. As a way to find a digital archives system for No Gun Ri, this study analyzed open-source software based on identified functions and requirements for participatory digital archives. Knowing the details of digital systems, this study discussed how contents for social memory can be stored and used in a digital system.

• Journal of Korea Multimedia Society
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• v.10 no.5
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• pp.583-593
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• 2007

We study the page replacement algorithms for demand paging, called CFLRU/C, CFLRU/E and DL-CFLRU/E, that reduce the number of erase operations and improve the wear-leveling degree of flash memory. Under the CFLRU/C and CFLRU/E algorithms, the victim page is the least recently used dean page within the pre-specified window. However, when there is not any dean page within the window, the CFLRU/C evicts the dirty page with the lowest frequency while the CFLRU/E evicts the dirty page with the highest number of erase operations. The DL-CFLRU/E algorithm maintains two page lists called the dean page list and the dirty page list, and first finds the page within the dean page list when it selects a victim. However, when it can not find any dean page within the dean page list, it evicts the dirty page with the highest number of erase operations within the window of the dirty page list. In this thesis, we show through simulation that the proposed schemes reduce the number of erase operations and improve the wear-leveling than the existing schemes like LRU.

• Journal of Advanced Marine Engineering and Technology
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• v.14 no.4
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• pp.46-56
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• 1990

Stress analysis of axi-symetric body with non-symetric loading and non-symetric given displacements is investigated in this paper using the finite element method. As the non-symetric load and non-symetric given displacements of axi-symetric body are generally periodic functions of angle .theta., the nodal forces and nodal displacements can be expanded in cosine and sine series, that is, Fourier series. Furthermore, using Euler's formula, the cosine and sine series can be converted into exponential series and it is prooved that the related calculus become more clear. Substituting the nodal displacements expanded in Fourier series into the strain components of cylindrical coordinates system, the element strains are expressed in series form and by the principal of virtual work, the element stiffness martix and element load vector are obtained for each order. It is also showed that if the non-symetric loads are even or odd functions of angle ${\theta}$ the stiffness matrix and load vector of the system are composed with only real numbers and relatively small capacity fo computer memory is enough for calculation.

• Journal of the HCI Society of Korea
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• v.13 no.4
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• pp.5-14
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• 2018

The Empathy for Dementia using Virtual Reality (EDuVR) system, developed by the Jeju Provincial Dementia Center, is a 3D video system capturing the experience of dementia in a first-person perspective using 360 degree vritual reality (VR) technology. It was developed to create a greater understanding of dementia and to help people empathize with individuals with dementia through an immersive VR experience. The EDuVR shows how a dementia patient has impairments in memory, orientation, language, judgment and problem solving, as well as problems with activities of daily living. The present study reported the effectiveness of the EDuVR experience in changing public awareness of, and attitude toward, dementia. Sixty-six participants were assigned to the EDuVR (n = 34) or the conventional education (n = 32) groups, and two types of questionnaires - attitude and awareness questionnaires - were administered to the subjects before and after the EDuVR experience or education. The simulator sickness and presence questionnaires were administered to the EDuVR group to assess cybersickness and presence of the VR experience. As a results, the attitude and awareness toward dementia patients changed positively in both the EDuVR and the conventional education groups, and these changes did not differ between two groups. Only one person reported a significant level of cybersicness after experiencing the EDuVR system. These results suggest that the EDuVR enhances the level of understanding and empathy for dementia and would be a useful tool for improving awareness in the general public.