• KSII Transactions on Internet and Information Systems (TIIS)
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• v.17 no.3
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• pp.938-957
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• 2023

The limited computing power of sensor nodes in wireless sensor networks (WSNs) and data tampering during wireless transmission are two important issues. In this paper, we propose a scheme for independent individual authentication of WSNs data based on digital watermarking technology. Digital watermarking suits well for WSNs, owing to its lower computational cost. The proposed scheme uses independent individual to generate a digital watermark and embeds the watermark in current data item. Moreover, a sink node extracts the watermark in single data and compares it with the generated watermark, thereby achieving integrity verification of data. Inherently, individual validation differs from the grouping-level validation, and avoids the lack of grouping robustness. The improved performance of individual integrity verification based on proposed scheme is validated through experimental analysis. Lastly, compared to other state-of-the-art schemes, our proposed scheme significantly reduces the false negative rate by an average of 5%, the false positive rate by an average of 80% of data verification, and increases the correct verification rate by 50% on average.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.7
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• pp.525-534
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• 2019

Water rocket is a pressurized liquid propellant rocket that shares the same basic principles of space launch vehicles. Water rockets can be used as an engineering educational material for the liquid rocket principles and the launch vehicle systems, far beyond the scope of K-12 level science education. In this paper, the principles and theories of water rocket propulsion and flight dynamics was investigated at the level of undergraduate rocket engineering classes. Also, the system level design and operation of water rocket is summarized by including the components of launch vehicle, launch pad, payload and recovery as well as altitude measurement methods.

• Journal of the Korea Safety Management & Science
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• v.18 no.4
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• pp.19-30
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• 2016

This paper addresses the problem of how to effectively use virtual reality(VR) for improving the quality of safety training systems. As the working environment and the working system in the industry are more and more complex and large-scaled, the concern with system safety is accordingly growing. Safety training systems are regarded as an effective way for increasing workers' interest in system safety and enhancing their ability of preventing and handling accidents/incidents. Recently, it has been reported that VR would be effectively used for improving the quality of safety training systems, with its technically specialized features. However, little attention has been given to the problem of how to effectively use VR for safety training systems. In order to make the best use of new technology such as VR, it is important to examine its advantages and disadvantages and the contexts to which its use can be beneficial. This paper firstly reviews the current status of safety training systems and the use of VR for safety training systems in the inside and outside of the country. Next, we summarize the interview with safety managers in four manufacturing companies, which was conducted to understand the requirements of stake-holders of the issue. Based on the review and the interview, we suggested the ways of using VR in safety training systems in an effective manner. They are described from the four perspectives: development and maintenance cost, lack of specialized workers, design of accident scenarios used with VR, and empirical demonstration of the effectiveness of VR in safety training.

• Bulletin of the Korean Chemical Society
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• v.33 no.12
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• pp.4255-4257
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• 2012

• Structural Engineering and Mechanics
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• v.73 no.6
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• pp.685-698
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• 2020

The dynamic stability of a functionally graded polymer microbeam reinforced by graphene oxides subjected to a periodic axial force is investigated. The microbeam is assumed to rest on an elastic substrate and is subjected to various immovable boundary restraints. The weight fraction of graphene oxides nanofillers is graded across the beam thickness. The effective Young's modulus of the functionally graded graphene oxides reinforced composite (FG-GORC) was determined using modified Halpin-Tsai model, with the mixture rule used to evaluate the effective Poisson's ratio and the mass density. An improved third order shear deformation theory (TSDT) is used in conjunction with the Chebyshev polynomial-based Ritz method to derive the Mathieu-Hill equations for dynamic stability of the FG-GORC microbeam, in which the scale effect is taken into account based on modified couple stress theory. Then, the Mathieu-Hill equation was solved using Bolotin's method to predict the principle unstable regions of the FG-GORC microbeams. The numerical results show the effects of the small scale, the graphene oxides nanofillers as well as the elastic substrate on the dynamic stability behaviors of the FG-GORC microbeams.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.5 no.2
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• pp.102-107
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• 2005

This paper presents the comparison and performance analysis for CPL and CMOS based designs. We have developed the Verilog-HDL codes for the proposed designs and simulated them using ModelSim for verifying the logical correctness and the timing properties of the proposed designs. The proposed designs are then analyzed at the layout level using LASI. The layouts of the proposed designs are simulated in Winspice for timing and power characteristics. The result shows that the new circuits presented consistently consume less power than the conventional design of the same circuits. It can also be seen that these circuits have the lesser propagation delay and thus higher speed than the conventional designs.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.5 no.3
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• pp.189-195
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• 2005

One of the major components of any pervasive system is its proactive behavior. Various models have been developed to provide system wide changes which would enable proactive behavior. A major drawback of these approaches is that they do not address the need to make use of existing applications without modifying the applications. To overcome this drawback, a middleware architecture called 'Concord' is proposed. Concord is based on a simple model which consists of Lookup Server and Database. The rewards for this simple model are many. First, Concord uses the existing computing infrastructure. Second, Concord standardizes the interfaces for all services and platforms. Third, new services can be added dynamically without any need for reconfiguration. Finally, Concord consists of Database that can maintain and publish the active set of available resources. Thus Concord provides a solid system for integration of various entities to provide seamless connectivity and enable proactive behavior.

• Journal of Navigation and Port Research
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• v.32 no.9
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• pp.693-698
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• 2008

The maritime education and training is executed in Asian countries according to The International Convention on Standards of Training, Certification and Watch keeping for Seafarers(STCW). However, mainly basic training and education takes in maritime universities, because this convention is minimum requirements to become junior mariner. So, until now researches have not developed to the stage of discussing how maritime universities of advanced shipping countries should pursue the direction of education in the new eras. Korea and Japan as the leading shipping countries in Asia, need to take initiatives in building a new education system in order to foster the next generation maritime expert. To enhance the professional abilities of maritime technologists in the new era, element design of science and technology relating to maritime issues and a new education system based on an amalgamation of maritime education and scientific and technological education were discussed.

• Journal of the Korea Safety Management & Science
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• v.9 no.3
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• pp.1-7
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• 2007

A roadmap for Electrical Safety Technology has been designed based on the study that has been contributed by the specialists, professors and researchers in electral safety field. The roadmap is divided into five major fields including, for instance, the electrical fire accidents roadmap. The other four roadmaps are for electrical shock accidents, electrical facilities accidents, electrical safety policies and electrical safety culture-education, respectively. Each roadmap has a purpose, a scope, and a technical characteristic. Following the roadmaps can result in significant reduction of electrical fire accidents, electrical shock accident victims and so forth. The result can also be utilized in guiding the planning and development of the future electrical safety technology.

• Journal of Korea Multimedia Society
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• v.17 no.11
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• pp.1263-1269
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• 2014

As rapid development of new hardware control interface technology, new concepts have been being proposed and emerged. In this paper, a new approach based on leap motion system is proposed. While we employ a position information from sensor, the hand gesture recognition is suggested with the pre-defined patterns. To do this, we design a recognition algorithm with hand gesture and finger patterns. We apply the proposed scheme to 3-dimensional avatar controling and editing software tool for making animation in the cyber space as a representative application. This proposed algorithm can be used to control computer systems in medical treatment, game, education and other various areas.