• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
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• 2003.10a
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• pp.263-268
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• 2003

Presently, research is hard to see design lot construction on actuality three-dimensional route although it applied three-dimensional techniques using constructed already two-dimensional plane design. Therefore, this research wishes to study about efficient decision-making at the public problem and design change that can happen during construction designing three-dimensional road and construction at actuality route location using VGIS.

• Transactions of Materials Processing
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• v.9 no.4
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• pp.372-378
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• 2000

A process model including the effects of both the texture development and ductile damage evolution In plane strain rolling is presented. In this process model, anisotropy from deformation texture and deterioration of mechanical properties due to growth of micro voids are directly coupled Into the virtual work expressions for the momentum and mass balances. Special treatments in obtaining the initial values of field variables in the nonlinear simultaneous equations for the anisotropic, dilatant viscoplastic deformation are also given. Mutual effects of the texture development and damage evolution during plate rolling are carefully examined in terms of the distribution of strain components, accumulated damage, R-value as well as yield surfaces.

• Journal of KIISE
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• v.43 no.1
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• pp.27-33
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• 2016

Virtualization has become one of the most helpful techniques in computing systems, and today it is prevalent in several computing environments including desktops, data-centers, and enterprises. However, since I/O layers are implemented to be oblivious to the I/O behaviors on virtual machines (VM), there still exists an I/O scalability issue in virtualized systems. In particular, when a multi-queue solid state drive (SSD) is used as a secondary storage, each system reveals a semantic gap that degrades the overall performance of the VM. This is due to two key problems, accelerated lock contentions and the I/O parallelism issue. In this paper, we propose a novel approach, including the design of virtual CPU (vCPU)-dedicated queues and I/O threads, which efficiently distributes the lock contentions and addresses the parallelism issue of Virtio-blk-data-plane in virtualized environments. Our approach is based on the above principle, which allocates a dedicated queue and an I/O thread for each vCPU to reduce the semantic gap. Our experimental results with various I/O traces clearly show that our design improves the I/O operations per second (IOPS) in virtualized environments by up to 155% over existing QEMU-based systems.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.10
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• pp.4902-4932
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• 2016

The popularity of network virtualization has recently regained considerable momentum because of the emergence of OpenFlow technology. It is essentially decouples a data plane from a control plane and promotes hardware programmability. Subsequently, OpenFlow facilitates the implementation of network virtualization. This study aims to provide an overview of different approaches to create a virtual network using OpenFlow technology. The paper also presents the OpenFlow components to compare conventional network architecture with OpenFlow network architecture, particularly in terms of the virtualization. A thematic OpenFlow network virtualization taxonomy is devised to categorize network virtualization approaches. Several testbeds that support OpenFlow network virtualization are discussed with case studies to show the capabilities of OpenFlow virtualization. Moreover, the advantages of popular OpenFlow controllers that are designed to enhance network virtualization is compared and analyzed. Finally, we present key research challenges that mainly focus on security, scalability, reliability, isolation, and monitoring in the OpenFlow virtual environment. Numerous potential directions to tackle the problems related to OpenFlow network virtualization are likewise discussed.

• Advances in aircraft and spacecraft science
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• v.8 no.4
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• pp.345-372
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• 2021

The analysis of nonlinear vibrations, buckling, post-buckling, flutter boundary determination and post-flutter behavior of a homogeneous curved plate assuming cylindrical bending is conducted in this article. Other assumptions include simply-supported boundary conditions, supersonic aerodynamic flow at the top of the plate, constant pressure conditions below the plate, non-viscous flow model (using first- and third-order piston theory), nonlinear structural model with large deformations, and application of mechanical and thermal loads on the curved plate. The analysis is performed with constant environmental indicators (flow density, heat, Reynolds number and Mach number). The material properties (i.e., coefficient of thermal expansion and modulus of elasticity) are temperature-dependent. The equations are derived using the principle of virtual displacement. Furthermore, based on the definitions of virtual work, the potential and kinetic energy of the final relations in the integral form, and the governing nonlinear differential equations are obtained after fractional integration. This problem is solved using two approaches. The frequency analysis and flutter are studied in the first approach by transferring the handle of ordinary differential equations to the state space, calculating the system Jacobin matrix and analyzing the eigenvalue to determine the instability conditions. The second approach discusses the nonlinear frequency analysis and nonlinear flutter using the semi-analytical solution of governing differential equations based on the weighted residual method. The partial differential equations are converted to ordinary differential equations, after which they are solved based on the Runge-Kutta fourth- and fifth-order methods. The comparison between the results of frequency and flutter analysis of curved plate is linearly and nonlinearly performed for the first time. The results show that the plate curvature has a profound impact on the instability boundary of the plate under supersonic aerodynamic loading. The flutter boundary decreases with growing thermal load and increases with growing curvature.

• Fashion & Textile Research Journal
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• v.7 no.4
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• pp.426-432
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• 2005

The health of feet is connected with individual's health and affects a man's activity. Shoes need to be designed to protect feet and to absorb the impact of land. Thus, design, comfort and economical efficiency are important factors of shoes. Consumers can choose suitable shoes for their feet in off-line shopping. However, in on-line shopping, because they can not wear shoes, compare to the off-line shopping, there are many problems in internet shopping. First, consumers can get limited information of shoes because they must search information of purchase without other's help. Second, because consumers can not get important information such as design, size and a comfort of wearing, they can not make a careful decision. Above these, the solution of user-oriented internet shopping is development of new type of prototype which is accessible to user and to offer visual information through 3D-virtual reality. The purpose of this study is to develpoment of shoes easy-order prototype so to reduce of internet shopping risk and offer to shopping convenience. Contents of the new prototype are as follows; 1. Consumers can print out a foot shaped plane figure and compare it to their foot. If the size of printed sheet is not proper, consumers can choose another size. Through this step, they can get their own size. 2. In 3D-virtual reality, consumers can get a various visual information. So they feel wearing comfort indirectly. It is expected that the result of this study would be an important case study to develop of shoes' easy-order prototype for a disabled person.

• Journal of Periodontal and Implant Science
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• v.48 no.2
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• pp.124-134
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• 2018

Purpose: Clinicians must examine tooth wear to make a proper diagnosis. However, qualitative methosds of measuring tooth wear have many disadvantages. Therefore, this study aimed to develop and evaluate quantitative parameters using the cusp area and volume of virtual dental models. Methods: The subjects of this study were the same virtual models that were used in our former study. The same age group classification and new tooth wear index (NTWI) scoring system were also reused. A virtual occlusal plane was generated with the highest cusp points and lowered vertically from 0.2 to 0.8 mm to create offset planes. The area and volume of each cusp was then measured and added together. In addition to the former analysis, the differential features of each cusp were analyzed. Results: The scores of the new parameters differentiated the age and NTWI groups better than those analyzed in the former study. The Spearman ${\rho}$ coefficients between the total area and the area of each cusp also showed higher scores at the levels of 0.6 mm (0.6A) and 0.8A. The mesiolingual cusp (MLC) showed a statistically significant difference (P<0.01) from the other cusps in the paired t-test. Additionally, the MLC exhibited the highest percentage of change at 0.6A in some age and NTWI groups. Regarding the age groups, the MLC showed the highest score in groups 1 and 2. For the NTWI groups, the MLC was not significantly different in groups 3 and 4. These results support the proposal that the lingual cusp exhibits rapid wear because it serves as a functional cusp. Conclusions: Although this study has limitations due to its cross-sectional nature, it suggests better quantitative parameters and analytical tools for the characteristics of cusp wear.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.6 s.237
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• pp.671-686
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• 2005

The transient nature and complex geometries of two-phase gas-liquid flows cause fundamental difficulties when measuring flow velocity using an electromagnetic flowmeter. Recently, a current-sensing flowmeter was introduced to obtain measurements with high temporal resolution (Ahn et al.). In this study, current-sensing flowmeter theory was applied to measure the fast velocity transients in slug flows. The velocity fields of axisymmetric gas-liquid slug flow in a vertical pipe were obtained using Volume-of-Fluid (VOF) method, and the virtual potential distributions for the electrodes of finite size were also computed using the finite volume method for simulating slug flow. The output signal prediction for slug flow was carried out from the velocity and virtual potential (or weight function) fields. The flowmeter was numerically calibrated to obtain the cross-sectional liquid mean velocity at an electrode plane from the predicted output signal. Two calibration parameters are proposed for this procedure: a flow pattern coefficient and a localization parameter. The flow pattern coefficient was defined by the ratio of the liquid resistance between the electrodes for two-phase flow with respect to that for single-phase flow, and the localization parameter was introduced to avoid errors in the flowmeter readings caused by liquid acceleration or deceleration around the electrodes. These parameters were also calculated from the computed velocity and virtual potential fields. The results can be used to obtain the liquid mean velocity from the slug flow signal measured by a current-sensing flowmeter.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.37B no.10
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• pp.877-888
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• 2012

Network virtualization technology is a crucial research issue of Future Internet which pursues a service-oriented architecture so-called NaaS (Network as a Service) or SDN (Software Defined Network). Network virtualization is expected to play an important role in Future Internet researches as a network testbed technology which enables innovative protocols to be experimented independently on a common testbed environment. We propose a control framework in order to provide user defined topology and bandwidth services with network virtualization and to separate and manage multiple-user traffics in a small and medium scale - single domain research network. The proposed framework (VIMS; Virtual network Integrated control and Management System) supports testbed expansions without any changes of heterogeneous virtual network support equipments through accommodation of each equipment's control plane. The framework shows a feasibility through applied to KOREN and we describe the differences and further study directions for improvement the framework comparing with GENI control framework.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.1951-1956
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• 2004

The transient nature and complex flow geometries of two-phase gas-liquid flows cause fundamental difficulties when measuring flow velocity using an electromagnetic flowmeter. Recently, a current-sensing flowmeter was introduced to obtain measurements with high temporal resolution (Ahn et $al.^{(1)}$). In this study, current-sensing flowmeter theory was applied to measure the fast velocity transients in slug flows. To do this, the velocity fields of axisymmetric gas-liquid slug flow in a vertical pipe were obtained using Volume-of-Fluid (VOF) method and the virtual potential distributions for the electrodes of finite size were also computed using the finite volume method for the simulated slug flow. The output signal prediction for slug flow was carried out from the velocity and virtual potential (or weight function) fields. The flowmeter was numerically calibrated to obtain the cross-sectional liquid mean velocity at an electrode plane from the predicted output signal. Two calibration parameters are required for this procedure: a flow pattern coefficient and a localization parameter. The flow pattern coefficient was defined by the ratio of the liquid resistance between the electrodes for two-phase flow with respect to that for single-phase flow, and the localization parameter was introduced to avoid errors in the flowmeter readings caused by liquid acceleration or deceleration around the electrodes. These parameters were also calculated from the computed velocity and virtual potential fields. The results can be used to obtain the liquid mean velocity from the slug flow signal measured by a current-sensing flowmeter.