• Journal of the Korean Society for Precision Engineering
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• v.22 no.3 s.168
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• pp.61-67
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• 2005

A dynamic model for flexure hinge-based compliant mechanisms is derived. The dynamic model of the previous works do not well describe the behaviors of rigid bodies in the compliant mechanism when the length of the flexure hinge is long. In this study, the effect on the length of the flexure hinge is pointed out and then the dynamic model is derived to overcome the length effect. For verification, modal analyses are carried out using the proposed dynamic model and FEM (Finite Element Method). Finally they are compared by the terms of modal frequency. As the result, the proposed dynamic model can be used in design and analysis of the compliant mechanism.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2003.05a
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• pp.275-280
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• 2003

This paper discusses on the dynamic responsed of an elastically restrained beam under a moving mass of constant velocity. Governing equations of motion taking into account of all inertia effects of the moving mass were derived by Galerkin's mode summation method, and Runge-Kutta integration method was applied to solve the differential equations. Numerical solutions for dynamic deflections of beams were obtained for the changes of the various parameters (spring stiffness, spring position, mass ratios and velocity ratios of the moving mass). In order to verify the numerical predictions for the dynamic response of the beam, experiments were conducted. Numerical solutions for the dynamic responses of the test beam have a good agreement with experimental ones.

• Journal of Digital Convergence
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• v.13 no.6
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• pp.151-156
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• 2015

In this paper, we have proposed personal multimodal biometric authentication system based on face detection, recognition and speaker verification for smart-phone environment. Proposed system detect the face with Modified Census Transform algorithm then find the eye position in the face by using gabor filter and k-means algorithm. Perform preprocessing on the detected face and eye position, then we recognize with Linear Discriminant Analysis algorithm. Afterward in speaker verification process, we extract the feature from the end point of the speech data and Mel Frequency Cepstral Coefficient. We verified the speaker through Dynamic Time Warping algorithm because the speech feature changes in real-time. The proposed multimodal biometric system is to fuse the face and speech feature (to optimize the internal operation by integer representation) for smart-phone based real-time face detection, recognition and speaker verification. As mentioned the multimodal biometric system could form the reliable system by estimating the reasonable performance.

• Smart Structures and Systems
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• v.12 no.3_4
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• pp.363-379
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• 2013

Dynamic displacement of structures is an important index for in-service structural condition and behavior assessment, but accurate measurement of structural displacement for large-scale civil structures such as long-span bridges still remains as a challenging task. In this paper, a vision-based dynamic displacement measurement system with the use of digital image processing technology is developed, which is featured by its distinctive characteristics in non-contact, long-distance, and high-precision structural displacement measurement. The hardware of this system is mainly composed of a high-resolution industrial CCD (charge-coupled-device) digital camera and an extended-range zoom lens. Through continuously tracing and identifying a target on the structure, the structural displacement is derived through cross-correlation analysis between the predefined pattern and the captured digital images with the aid of a pattern matching algorithm. To validate the developed system, MTS tests of sinusoidal motions under different vibration frequencies and amplitudes and shaking table tests with different excitations (the El-Centro earthquake wave and a sinusoidal motion) are carried out. Additionally, in-situ verification experiments are performed to measure the mid-span vertical displacement of the suspension Tsing Ma Bridge in the operational condition and the cable-stayed Stonecutters Bridge during loading tests. The obtained results show that the developed system exhibits an excellent capability in real-time measurement of structural displacement and can serve as a good complement to the traditional sensors.

• Nuclear Engineering and Technology
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• v.51 no.2
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• pp.444-452
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• 2019

To assess the availability of a nuclear power plant's dynamic systems, it is necessary to consider the impact of dynamic interactions, such as components, software, and operating processes. However, there is currently no simple, easy-to-use tool for assessing the availability of these dynamic systems. The existing method, such as Markov chains, derives an accurate solution but has difficulty in modeling the system. When using conventional fault trees, the reliability of a system with dynamic characteristics cannot be evaluated accurately because the fault trees consider reliability of a specific operating configuration of the system. The dynamic reliability graph with general gates (DRGGG) allows an intuitive modeling similar to the actual system configuration, which can reduce the human errors that can occur during modeling of the target system. However, because the current DRGGG is able to evaluate the dynamic system in terms of only reliability without repair, a new evaluation method that can calculate the availability of the dynamic system with repair is proposed through this study. The proposed method extends the DRGGG by adding the repair condition to the dynamic gates. As a result of comparing the proposed method with Markov chains regarding a simple verification model, it is confirmed that the quantified value converges to the solution.

• Journal of KIISE:Software and Applications
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• v.32 no.7
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• pp.663-673
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• 2005

An analysis model for the dynamics information of two-dimensional time-series patterns is described. In the proposed model, two novel transforms that visualize the dynamic characteristics are proposed. The first transform, referred to as speed equalization, reproduces a time-series pattern assuming a constant linear velocity to effectively model the temporal characteristics of the signing process. The second transform, referred to as velocity transform, maps the signal onto a horizontal vs. vertical velocity plane where the variation oi the velocities over time is represented as a visible shape. With the transforms, the dynamic characteristics in the original signing process are reflected in the shape of the transformed patterns. An analysis in the context of these shapes then naturally results in an effective analysis of the dynamic characteristics. The proposed transform technique is applied to an online signature verification problem for evaluation. Experimenting on a large signature database, the performance evaluated in EER(Equal Error Rate) was improved to 1.17$\%$ compared to 1.93$\%$ of the traditional signature verification algorithm in which no transformed patterns are utilized. In the case of skilled forgery experiments, the improvement was more outstanding; it was demonstrated that the parameter set extracted from the transformed patterns was more discriminative in rejecting forgeries

• The Journal of Korean Association of Computer Education
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• v.12 no.4
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• pp.65-75
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• 2009

The result verification is necessary to support a guarantee for the correctness of the task results be executed by any unspecified resources in desktop grid environments. Typically, voting-based and trust-based result verification schemes have been used in the environments. However, these suffer from two potential problems: waste of resources due to redundant replicas of each task and increase in turnaround time due to the inability to deal with a dynamic changeable execution environment. To overcome these problems, we propose a fuzzy inference-based replication scheme which can adaptively determine the number of replicas per task by using both trusty degree and result return probability of resources. Therefore our proposal can reduce waste of resources by determining the number of replicas meeting with a dynamic execution environment of desktop grids, not to mention an enhancement of turnaround time for entire asks. Simulation results show that our scheme is superior to other ones in terms of turnaround time, the waste of resources, and the number of re-replications per task.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.49 no.6
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• pp.505-513
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• 2021

We propose an autonomous mission management software design and verification technique for unmanned aerial vehicles to autonomously mitigate dynamic situation changes occurred in the inside and outside of an aircraft in compliance with the mitigation priority order. The proposed autonomous mission management software is designed in a modular architecture that consists of concurrently executing multiple threads. To verify it, we suggest three verification steps: 1) software integration by checking the expected request/response messages between the threads for all possible dynamic situation changes; 2) integration test to verify the software functionality; 3) performance test to verify the quantitative software performance. Especially, the software integration test environment is built and utilized to carry out the integration and performance tests.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.5
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• pp.789-798
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• 2020

This paper considers the development of the dynamic analysis model and simulation-based operation safety estimation of A-Frame to be applied to the test evaluation support vessel for real sea test. The support vessel will be manufactured by modifying the existing offshore support vessel. Also, development and installation of various sensors and supporting facilities for test evaluation are under preparation. Among these facilities, A-Frame is an equipment that transfers marine equipment from ship deck to the sea floor, and is being designed to transfer up to 50 ton class equipment. However, the A-Frame is a moving equipment using hydraulic cylinders. When the 50 ton equipment is attached and transferred to A-Frame, the buckling of cylinders may occur or A-Frame becomes inoperable due to the influence of huge inertia. For this reason, safety verification should be performed using dynamic analysis techniques that can take into account huge inertia forces in the design of A-Frame. Therefore, in this study, A-Frame and ship behavior were modeled using dynamic analysis method, and the applied loads of various equipment including hydraulic cylinder of A-Frame was measured and the operation safety review was performed.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.27 no.4
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• pp.811-820
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• 2017

Software automatic technology research recently focuses not only on generating a single path test-case, but also on finding an optimized path to reach the vulnerability through various test-cases. Although Dynamic Symbolic Execution (DSE) technology is popular among these automatic technologies, most DSE technology researches apply only to Linux binaries or specific modules themselves. However, most software are vulnerable based on input files. Therefore, this paper proposes an input file based dynamic symbolic execution method for software vulnerability verification. As a result of applying it to three kinds of actual binary software, it was possible to create a test-case effectively reaching the corresponding point through the proposed method. This demonstrates that DSE technology can be used to automate the analysis of actual software.