• The Journal of Korean Institute of Communications and Information Sciences
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• v.41 no.12
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• pp.1793-1800
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• 2016

Network virtualization is considered as an enabling technology to accomodate recently introduced new services such as cloud services and data center networks on top of the existing network environment. In this paper, an efficient virtual network mapping method is proposed which takes account of the location and resource requirements of virtual nodes and the bandwidth requirements of virtual links. The proposed method sets bandwidth as the priority metric for network mapping, and searches for a set of substrate nodes and paths that houses the virtual nodes and virtual links. Through the simulation experiments, it is verified that the proposed method provides better cost to revenue ratio and fast experiment time without degrading success rate of virtual network mapping.

• Proceedings of the KIEE Conference
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• 2002.07d
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• pp.2625-2627
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• 2002

A virtual laboratory for measurement and instrumentation must aim to realize an integrated environment. To achieve this goal, we designed and implemented a client/server distributed environment and developed a web-based virtual laboratory system for electronic circuits. The proposed virtual laboratory system is composed of four important components : Principle Classroom, Virtual Experiment Classroom, Evaluation Classroom and Overall Management System. Through our virtual laboratory, the learners will be capable of learning the concepts and theories related to electronic circuit experiments and how to operate the experimental equipments. Also, every activity occurred in our virtual laboratory is recorded on database and printed out on the preliminary report form. All of these can be achieved by the aid of the Management System. The database connectivity is made by PHP and the virtual laboratory environment is set up slightly differently for each learner. Finally, we have obtained several affirmative effects such as reducing the total experimental hours and the damage rate for experimental equipments and increasing learning efficiencies as well as faculty productivity.

• Journal of Korean Elementary Science Education
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• v.38 no.2
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• pp.275-286
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• 2019

The purpose of this study is to investigate the features of inquiry activities using technology in the 2015 revised elementary science digital textbooks. For this, we analyzed the features of inquiry context and inquiry method presented in inquiry activities using three kinds of technology: Virtual experiment, virtual reality and augmented reality. As a result, firstly, the most common types of 77 inquiry activities were realistic type which shows the phenomenon actually and vividly as possible and realistic-abstract type which shows the phenomena with the abstract concepts. Second, the ways of using three technologies were different depending on the processes of inquiry and the sub-domains of science. For example, virtual experiment technologies were mostly used in the contents of physics and chemistry with the inquiry context of realistic-abstract type for investigating the relationship between variables of experiments and describing the phenomena mechanically. On the other hand, virtual reality and augmented reality techniques tended to be used more frequently in biology and earth science contents with the inquiry context of realistic type for observing and describing the phenomena. Finally, we discussed educational implications in terms of developing and applying technology-based inquiry activities.

• The Journal of Korean Association of Computer Education
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• v.11 no.1
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• pp.23-32
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• 2008

In this paper, we have investigated the education effect of a web-based virtual laboratory for digital logic circuits which consists of multimedia contents about the usages of equipments for logic circuit experiments and the experimental logic circuits. In case of the engineering experiment of the lower grades in universities, preunderstanding about the usages of experimental equipments and the experimental circuits is necessary for the learners to conduct the experiments well. But it is impossible for the learners to have access to the real experimental equipments earlier due to the lack of equipments and the difficulty in management of the equipments. We have implemented the digital logic circuit virtual laboratory which provides the same experimental environment as a real experimental lab, and the learner can conduct the same experiments as the real ones before the real laboratory class. The learners using the laboratory have reduced the experiment completion time by the average of about 8.2% during a term, compared with the learners not using the lab.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.9 no.5
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• pp.1184-1192
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• 2008

There have been a large number of trials of the experimental education in engineering using virtual laboratories implemented in virtual space, namely on the Web. Although virtual education is regarded as an effective educational means that overcomes the limit of time and space and bring high teaming effects, the problem of lack of reality must be solved. The present study proposed and implemented a real-time remote laboratory as a solution for the problem of lack of reality in virtual education. The remote laboratory provides functions with which learners can perform experiments by remote-controlling circuits and equipment related to experiments and practices on the Web and gets data and image information, so through it learners can make realistic experiments at any time and in any place. The remote laboratory module based on Internet open sources such as JAVA Web start technology, FTP technology and Telnet technology in server-client environment can be implemented at low cost, and is effectively applicable to engineering experiment education in various areas related to real-time hardware control.

• Journal of Power System Engineering
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• v.13 no.2
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• pp.71-82
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• 2009

This paper presents a real-time haptic rendering method for a realistic force feedback in a remote environment with varying communication time-delay. The remote environment is assumed as a virtual environment based on a computer graphics, for example, on-line shopping mall, internet game and cyber-education. The properties of a virtual object such as stiffness and viscosity are assumed to be unknown because they are changed according to the contact position and/or a penetrated depth into the object. The DARMAX model based output estimator is proposed to trace the correct impedance of the virtual object in real-time. The output estimator is developed on the input-output relationship. It can trace the varying impedance in real-time by virtue of P-matrix resetting algorithm. And the estimator can trace the correct impedance by using a white noise that prevents the biased input-output information. Realistic output forces are generated in real-time, by using the inputs and the estimated impedance, even though the communication time delay and the impedance of the virtual object are unknown and changed. The generated forces trace the analytical forces computed from the virtual model of the remote environment. Performance is demonstrated by experiments with a 1-dof haptic device and a spring-damper-based virtual model.

• Journal of Mechanical Science and Technology
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• v.14 no.9
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• pp.956-967
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• 2000

In this paper, we explore the issues of force display in the cooperative virtual environment shared by multiple users distributed over the network with heterogeneous hardware platforms. The proposed method is to cope with the problem of small time delay and the difference of sampling rate in the distributed configuration. In the proposed approach the interaction forces of the participants are just treated as the independent sources of acceleration. Thus the action of a participant simply changes the acceleration of the virtual object and consequently the states of the virtual object will be updated. When the updated states are reported to all the participants, the information on the time of state changes is delivered, too. Employing the discrete state information updated by the other users, each user modifies his own virtual environment and pseudo-realtime simulation can be realized. Excluding the software interface and the communication technique, it is proposed the simulation method for the operation of respective users and the way of calculating the driving input to the display device. For experimental verification we construct a cooperative virtual environment shared by two remote users and outline the results of experiments.

• The Journal of the Korea Contents Association
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• v.17 no.11
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• pp.446-460
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• 2017

The purpose of this study is to discover the nature of users' flow experience in virtual reality education services. To this end, we analyzed the factors that affect the user's immersion in virtual reality by applying grounded theory, which is one of the qualitative research method. An experiment was conducted on 11 subjects who were interested in conducting virtual reality education, and conducted interviews after experiments. All of the interviews were documented and configured to construct a paradigm model through the steps of opening coding, axial coding, selective coding. Based on the results, it presents suggestions for future virtual reality education services.

• Architectural research
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• v.22 no.4
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• pp.155-162
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• 2020

Numerous scholars have explored the modeling, control, and optimization of energy systems in buildings, offering new insights about technology and environments that can advance industry innovation. Eye trackers deliver objective eye-gaze data about visual and attentional processes. Due to its flexibility, accuracy, and efficiency in research, eye tracking has a control scheme that makes measuring rapid eye movement in three-dimensional space possible (e.g., virtual reality, augmented reality). Because eye movement is an effective modality for digital interaction with a virtual environment, tracking how users scan a visual field and fix on various digital objects can help designers optimize building environments and materials. Although several scholars have conducted Virtual Reality studies in three-dimensional space, scholars have not agreed on a consistent way to analyze eye tracking data. We conducted eye tracking experiments using objects in three-dimensional space to find an objective way to process quantitative visual data. By applying a 12 × 12 grid framework for eye tracking analysis, we investigated how people gazed at objects in a virtual space wearing a headmounted display. The findings provide an empirical base for a standardized protocol for analyzing eye tracking data in the context of virtual environments.

• The Journal of Korean Association of Computer Education
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• v.10 no.6
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• pp.11-18
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• 2007

The proposed virtual laboratory system for digital logic circuits is composed of two main sessions, which are concept-learning session and virtual experiment session by virtual digital kit. During concept-learning session the learners can easily understand the important principles in the digital circuits to be performed. In addition, during virtual laboratory session the virtual experiments are performed by assembling and connecting the circuits on the virtual bread board, applying input voltages, making the output measurements, and comparing and transmitting the virtual experimental data. Every activity done during the virtual laboratory session is recorded on database and will be provided with the learners as a preliminary report form including personal information. Thus, the educators may check out the submitted preliminary report to estimate how well the learners understand the circuit operations. Finally, in order to show the validity of our virtual laboratory system we investigated and analysed the damage rate of real experimental equipment during class and assessed student performance on the five quizzes for one semester.