• Journal of Communications and Networks
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• v.11 no.6
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• pp.615-625
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• 2009

Worldwide inter-operability for microwave access (WiMAX) is a promising technology that provides high data throughput with low delays for various user types and modes of operation. While much research had been conducted on physical and MAC layers, little attention has been paid to a comprehensive and efficient security solution for WiMAX. We propose a hybrid security solution combining identity-based cryptography (IBC) and certificate based approaches. We provide detailed message exchange steps in order to achieve a complete security that addresses the various kind of threats identified in previous research. While attaining this goal, efficient fusion of both techniques resulted in a 53% bandwidth improvement compared to the standard's approach, PKMv2. Also, in this hybrid approach, we have clarified the key revocation procedures and key lifetimes. Consequently, to the best of knowledge our approach is the first work that unites the advantages of both techniques for improved security while maintaining the low overhead forWiMAX.

• International Journal of Advanced Culture Technology
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• v.4 no.4
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• pp.81-86
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• 2016

In this paper, we propose a simple and effective vision-based tracking controller design for autonomous object tracking using multicopter. The multicopter based automatic tracking system usually unstable when the object moved so the tracking process can't define the object position location exactly that means when the object moves, the system can't track object suddenly along to the direction of objects movement. The system will always looking for the object from the first point or its home position. In this paper, PID control used to improve the stability of tracking system, so that the result object tracking became more stable than before, it can be seen from error of tracking. A computer vision and control strategy is applied to detect a diverse set of moving objects on Raspberry Pi based platform and Software defined PID controller design to control Yaw, Throttle, Pitch of the multicopter in real time. Finally based series of experiment results and concluded that the PID control make the tracking system become more stable in real time.

• Journal of Welding and Joining
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• v.8 no.3
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• pp.60-69
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• 1990

Plasma arc cutting is a fusion cutting process in which a gas-constricted arc is employed to produce a high-temperature, high-velocity plasma jet on the workpiece. This process provides some advantages such as increased cutting velocity, excellent working accuracy and the ability to cut special materials (widely used stainless steels and Al-alloys, for example), when compared with iconventional oxyfuel gas cutting. From the view point of price and reliability of the power source, plasma arc cutting has also some distinct advantages over laser beam cutting. High-speed machines with NC or CNC systems are needed for the plasma arc or laser beam cutting process, while for oxyfuel gas cutting, low-speed machines with copying templates or optical-shape tracking sensors can be applied. The low price and high flexibility of the microprocessor arc contributing more and more the application of CNC system in the plasma arc cutting process, as in other manufacturing fields. From these points of view, a microprocessor-based plasma arc cutting system was developed by using a reference-pulse system, and its performance was tested. The interpolating routines were programmed in the assembly language for saving the memory volume and improving the compouting speed, which has an intimate relationship with the available cutting velocity.

• Progress in Superconductivity and Cryogenics
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• v.4 no.2
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• pp.73-77
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• 2002

In order to derive the detailed design of Thermal Shield Cryopanel. which plays a role to make the Tokamak Nuclear Fusion Equipment work at both static and efficient conditions the commercially available software package FLUENT Version 5.3, was utilized. This study investigated the effects of thermal sources and distributions on the temperatures of Lid. Body. Base. and EH-Port Cryopanel by the numerical technique whose grid generations cover the solid and 9as region of the panel. The physical model of the Thermal Shield Cryopanel is that the 10mm diameter of the pipe with 1mm thickness is soldered on the Stainless steel Panel with 4mm thickness. The heat fluxes to the panel are assumed to be by thermal radiation in the vacuum space and by conduction through the supporters. The inlet conditions of Helium gas are 20 atmospheric Pressures and 60K temperature. The panel shapes with cooling Pipes and the operational conditions to keep appropriate temperature distribution of Thermal Shield Cryopanel Have been found and suggested.

• International Journal of Advanced Culture Technology
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• v.3 no.2
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• pp.118-123
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• 2015

IT environment gets more complicated in terms of open platform, network standards, device design and hardware, etc. Smart network and application are in the fields of corporate as well as national competition for future fusion technology. In development environment focused on computers, the ideas of authoring tool have been presented in terms of improved software productivity. In smart environment where subdividing works are consecutively done, current authoring tool should be effectively updated for effective development of programs and easier access to business works. The basic concept of a new conceptual App development tool, Smart App Authoring Tool, which has been designed in this study and enables to apply on-site requirements to smart phones, is to develop Apps on the level using easy-to-learn Word or Excel in a computer. Therefore, this study is intended to design a conceptual Smart App Authoring Tool to optimize the cost and time for developing and maintaining new application services under various smart phone platform environments. Based on the performance of smart app authoring tool herein, every people can develop a smart app program at moderate level. So this paper have designed a conceptual smart app authoring tool. This study presented educational efficiency of the authoring tool by developing business Apps under various business environments and applying them under university and high school environments.

• The KIPS Transactions:PartD
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• v.9D no.1
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• pp.135-144
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• 2002

Multimedia systems design generally requires a collaborative effort from a group of designers with a variety of backgrounds and tasks, such as content experts, instructional designers, media specialists, users, and so forth. The fact that the designers have totally different backgrounds and tasks may hinder their collaboration. This research develops a collaborative design tool for multimedia systems design, called the Designer's Cafe, with which multimedia designers can share their design knowledge on the Web freely. Designer's Cafe consists of three intelligent agents that are designed for supporting collaboration activities of multimedia designers. The intelligent agents are implemented by using JAVA SCRIPT and COLD FUSION. By using the tool, designers create, revise, and share their knowledge/ideas in very structured ways. The structured design process might enhance the collaboration activities of designers while designing a multimedia system within a virtual working space.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2014.11a
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• pp.216-217
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• 2014

Science & Technology(S&T) is the most important thing to attain competitiveness in the 21st century. Our traditional S&T policies have been forcused on hardware infra structure. We should consider software of S&T to enhance effectiveness. S&T Should be had a correct understanding method of the creation for S&T culture. It implies that S&T policy should consider nonmaterial factors which include social, environmental and culture. Under this background, The purpose of this paper is to seek new S&T policy. Therefor this paper deals with how we can prepare for the future S&T policy and classify the change of S&T policy of korea. In addition, Recent construction sector integration and fusion technologies in various areas of research and planning system is being maintained by the system. Past experience of conservative management in this emerging technology-driven technology commercialization in management of technology through the convergence of various technologies and to find synergies to secure the future of construction technology because it is a need.

• Proceedings of the KIEE Conference
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• 2001.07d
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• pp.1984-1986
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• 2001

In order to provided continuous solutions, latest developing navigation systems tend to integrate GPS receiver with INS or DR. Using the GPS carrier-phase measurements, an attitude GPS receiver with three antennas obtain the 3-dimensional attitude such as roll, pitch, and heading as well as position and velocity. With these angle measurements, in the attitude GPS/INS integrated system, attitude or gyro errors can be directly compensated. In this paper, we develop an integrated navigation system that combines attitude GPS receiver with INS. The performance of real-time integrated navigation system is determined by not only the implements of integration filter but also the synchronization of measurements. To meet these real-time requirements, the navigation software is implemented in multi-tasking structure in this paper. We also employ time-synchronization technique in the multi-sensor fusion. Experimental results show that the performance of the attitude GPS/INS integrated system is consistent even when cycle-slip occurs in carrier-phase measurements.

• Composites Research
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• v.31 no.6
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• pp.311-316
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• 2018

In the present study, the effect of GO in damping capacity of CF/epoxy laminates was studied via free vibration analysis. The composite laminates were manufactured by using vacuum assisted resin transfer molding technique. The damping properties of the prepared hybrid composites were determined in terms of natural frequency and damping ratio in free vibration test. The foremost aspire of this investigation was to compare the vibration properties i.e. natural frequency and modal damping of the prepared composites with the numerical results. The numerical study was carried out via FEA using $ANSYS^{TM}$ workbench software. The parametric study of the numerical models was also studied considering the beam free length and the beam thickness. It was found that the incorporation of GO enhanced the damping capacity of the composite and the variation of natural frequencies in mode1varied by 2-5% compared to the experimental study.

• KIPS Transactions on Software and Data Engineering
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• v.10 no.8
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• pp.319-330
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• 2021

Recently, in the field of open domain natural language question answering, multi-task, multi-hop question answering has been studied extensively. In this paper, we propose a novel deep neural network model using hierarchical graphs to answer effectively such multi-task, multi-hop questions. The proposed model extracts different levels of contextual information from multiple paragraphs using hierarchical graphs and graph neural networks, and then utilize them to predict answer type, supporting sentences and answer spans simultaneously. Conducting experiments with the HotpotQA benchmark dataset, we show high performance and positive effects of the proposed model.