• KSII Transactions on Internet and Information Systems (TIIS)
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• v.12 no.9
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• pp.4144-4165
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• 2018

Software-defined networking (SDN) has emerged as a promising technology for network programmability and experiments. In this work, we focus on virtual network embedding in multiple controllers SDN network. In SDN virtualization environment, virtual SDN networks (vSDNs) operate on the shared substrate network and managed by their each controller, the placement and load of controllers affect vSDN embedding process. We consider controller placement, vSDN embedding, controller adjustment as a joint problem, together considering different quality of service (QoS) requirement for users, formulate the problem into mathematical models to minimize the average time delay of control paths, the load imbalance degree of controllers and embedding cost. We propose a heuristic method which places controllers and partitions control domains according to substrate SDN network, embeds different QoS constraint vSDN requests by corresponding algorithms, and migrates switches between control domains to realize load balance of controllers. The simulation results show that the proposed method can satisfy different QoS requirement of tenants, keep load balance between controllers, and work well in the acceptance ratio and revenue to cost ratio for vSDN embedding.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.10
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• pp.1101-1108
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• 2015

In this paper, to provide a method and system for providing a network separation virtual machine environment. How to provide this virtual machine environment include phase generating necessary virtual resource requirement for the perform of virtual function and transfer to network changing protocol about request of registration virtual resource. For this reason, Registration procedure is to use a virtual machine for a virtual computing resource allocation and separation combined network any time, it became possible between servers and clients, or mobile phone. At any time, it is possible to process the work in the same environment as in a computer to access the Internet.

• Journal of the Korea Society of Computer and Information
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• v.14 no.11
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• pp.31-40
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• 2009

The most common cleaning methods of cleaning robot can be divided into two categories: the random and the boustrophedon method. A cleaning robot using the random method moves straight until it bumps into an obstacle. If it collides with an obstacle, the cleaning robot turns a specific angle and continues moving straight. Therefore, the random method often tends to clean the already clean area repeatedly. In addition, it takes a long time to complete cleaning. A cleaning robot using the boustrophedon method moves straight until it collides with an obstacle. If it meets an obstacle, the cleaning robot moves to the next uncleaned space through turning and moving ahead. when resuming cleaning from the new region, a cleaning robot moves in the direction opposite to the direction of the previous cleaning. Because the boustrophedon method cleans a cleaning space more densely, its performance is excellent in an obstacle-free space or a small space. However, In a space with obstacles or a complex structure, it takes a long time to complete the cleaning work. Cleaning should be systematically approached with a good understanding of the work area. The virtual map-based cleaning robot proposed in this paper cleaned a work space efficiently. The efficiency of the proposed method was measured through simulation.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.5 s.98
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• pp.112-123
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• 1999

Virtual reality is becoming a powerful tool for various applications such as training, entertainment, surgery, tele-robotics etc. One potential use for virtual reality is to allow several users to interact in a single virtual environment, for example several students sitting in front of different computers connected over a network. In this paper, we present a loosely coupled architecture of haptic display in the multi-user virtual world. The method of controlling haptic devices as well as the way of configuring individual haptic display system are addressed. We will develop an experimental virtual reality system for two remote users and conclude with an experimental work for the task of a multi-player ping-pong and grasping of a common object.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.54 no.6
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• pp.287-293
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• 2005

Equations have been derived for computing electromagnetic forces by using the Continuum Design Sensitivity Analysis based on the Continuum Mechanics and the Virtual Work Principle. The resultant expressions have similar terms relating to the Korteweg-Holmholz force density, Maxwell Stress Tensor and Magnetic Charge Method but numerical implementation of the proposed scheme leads to efficient calculation and improved accuracy. In addition, the method can be easily applied to computing the magnetic force distribution as well as the global force. Results show the aforementioned advantages in comparison with the conventional methods.

• International conference on construction engineering and project management
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• 2015.10a
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• pp.248-251
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• 2015

High injury and fatality rates remain a serious problem in the construction industry. Many construction injuries and fatalities can be prevented if workers can recognize potential hazards and take actions in time. Many efforts have been devoted in improving workers' ability of hazard recognition through various safety training and education methods. However, a reliable approach for evaluating this ability is missing. Previous studies in the field of human behavior and phycology indicate that the visual focus of attention (VFOA) is a good indicator of worker's actual focus. Towards this direction, this study introduces an automated approach for estimating the VFOA of equipment operators using a head orientation-based VFOA estimation method. The proposed method is validated in a virtual reality scenario using an immersive head mounted display. Results show that the proposed method can effectively estimate the VFOA of test subjects in different test scenarios. The findings in this study broaden the knowledge of detecting the visual focus and distraction of construction workers, and envision the future work in improving work's ability of hazard recognition.

• Convergence Security Journal
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• v.21 no.3
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• pp.25-30
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• 2021

Due to the current COVID-19 pandemic, companies and institutions are introducing virtual desktop technology, one of the logical network separation technologies, to establish a safe working environment in a situation where remote work is provided. With the introduction of virtual desktop technology, companies and institutions can operate the network separation environment more safely and effectively, and can access the business network quickly and safely to increase work efficiency and productivity. However, when introducing virtual desktop technology, there is a cost problem of high-spec server, storage, and license, and it is necessary to supplement in terms of operation and management. As a countermeasure to this, companies and institutions are shifting to cloud computing-based technology, virtual desktop service (DaaS, Desktop as a Service). However, in the virtual desktop service, which is a cloud computing-based technology, the shared responsibility model is responsible for user access control and data security. In this paper, based on the shared responsibility model in the virtual desktop service environment, we propose a cloud-based hardware security module (Cloud HSM) and edge-DRM proxy as an improvement method for user access control and data security.

• Journal of Welding and Joining
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• v.27 no.6
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• pp.55-61
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• 2009

This study aims for determination of cutting work envelope of an articular robot for H-beam cutting. The robot has its own work envelope. The cutting of piece with groove requires the specific position of the torch which contracts the work envelope. This study suggested the new method to determine the cutting work envelope for this case. The method simplified the problem by use of the combination of inverse kinematics and forward kinematics. The method was used for cutting the H-beam with groove. The cutting work envelope was determined easily. The result was verified by 3D simulation system which implements the articular robot with 6 axes and the H-beam in the virtual shop.

• Korean Institute of Interior Design Journal
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• no.40
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• pp.158-164
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• 2003

The rapid development of information technology has much influence on architectural design. Collaboration beyond time and space has been possible by networking the work environment and digital products. Thus, the virtual design studio on architectural design is getting more important than ever before. This research investigates a virtual design studio methodology for effective collaboration. The building design process and the communication model are studied and possible modes of design collaboration are defined. This paper proposes an internet-based Virtual Reality(VR) communication tool as well as new design methodology that we call the 'Hybrid Design Methodology'. We expect that this design methodology will dramatically increase design feedbacks, and thus results in better design alternatives. There are two issues involved in developing the collaborative virtual design studio: 1) an intuitive interface that presents collaborative relations, and 2) three-dimensional computer-mediated communication tool using sketch as a modeling method. Further research issues identified at the end of the research include developing algorithms that translate mapping images to polygons for the drafting phase in the design process.

• Structural Engineering and Mechanics
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• v.7 no.2
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• pp.159-180
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• 1999

The present paper shows a new non-tensorial approach to derive basic equations for various structural analyses. It can be used directly in numerical computation procedures. The aim of the paper is, however, to show that the approach serves as an excellent tool for analytical purposes also, working as a link between analytical and numerical techniques. The paper gives a method to derive, at first, expressions for strains in general beam and shell analyses, and secondly, the governing equilibrium equations. The approach is based on the utilization of local fixed Cartesian coordinate systems. Applying these, all the definitions required are the simple basic ones, well-known from the analyses in common global coordinates. In addition, the familiar principle of virtual work has been adopted. The method will be, apparently, most powerful in teaching the theories of curved beam and shell structures for students not familiar with tensor analysis. The final results obtained have no novelty value in themselves, but the procedure developed opens through its systematic and graphic progress a new standpoint to theoretical considerations.