• Journal of the Korean Geotechnical Society
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• v.19 no.4
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• pp.145-153
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• 2003

The resonant column testing determines the shear modulus and material damping factor dependent on the shear strain magnitude, based on the wave-propagation theory. The determination of the dynamic soil properties requires the theoretical formulation of the dynamic behavior of the resonant column testing system. One of the theoretical formulations is the use of the wave equation for the soil specimen in the resonant column testing device. Wood, Richart and Hall derived the wave equation by assuming the linear elastic soil, and didn't take the material damping into consideration. Hardin incorporated the viscoelastic damping of soil in the wave equation, but he had to assume the material damping factor for the determination of the shear modulus. For the better theoretical formulation of the resonant column testing, this study derived a new wave equation to include the viscosity of soil, and proposed an approach for the solution. Also, in this study, the equation of motion for the testing system, which is another approach of the theoretical formulation of the resonant column testing, was also derived. The equation of motion leads to the better understanding of the resonant column testing, which includes the dynamic magnification factor and the phase angle of the response. For the verification of the proposed equation of motion for the resonant column testing, the finite element analysis was performed for the resonant column testing. The comparison of the dynamic magnification factors and the phase angles far the system response were performed.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.1259-1268
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• 2006

Dynamic pile loading test using PDA was introduced in 1994. Because of its economy and relatively easy and simple procedure, the number of PDA application increased quite rapidly. It is assumed that more than 10,000 dynamic pile loading tests are done annually. While the number of testing increases sharply, the quality of the tests does not really improve but the number of serious problems due to improper testing increases. According to the limited experiences of the authors, the common problems found in most of the cases are caused by ignorance of the most basic and fundamental requirements. In this paper some case histories are explained and the proposed solution is introduced.

• Smart Structures and Systems
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• v.14 no.6
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• pp.1105-1129
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• 2014

The unscented Kalman filter (UKF) has been developed for nonlinear model parametric identification, and it assumes that the model parameters are symmetrically distributed about their mean values without any constrains. However, the parameters in many applications are confined within certain ranges to make sense physically. In this paper, a constrained unscented Kalman filter (CUKF) algorithm is proposed to improve accuracy of numerical substructure modeling in hybrid testing. During hybrid testing, the numerical models of numerical substructures which are assumed identical to the physical substructures are updated online with the CUKF approach based on the measurement data from physical substructures. The CUKF method adopts sigma points (i.e., sample points) projecting strategy, with which the positions and weights of sigma points violating constraints are modified. The effectiveness of the proposed hybrid testing method is verified by pure numerical simulation and real-time as well as slower hybrid tests with nonlinear specimens. The results show that the new method has better accuracy compared to conventional hybrid testing with fixed numerical model and hybrid testing based on model updating with UKF.

• Proceedings of the KWS Conference
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• 1990.11a
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• pp.106-110
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• 1990

• Journal of the Earthquake Engineering Society of Korea
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• v.23 no.1
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• pp.43-54
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• 2019

Existing reinforced concrete frame buildings designed for only gravity loads have been seismically vulnerable due to their inadequate column detailing. The seismic vulnerabilities can be mitigated by the application of a column retrofit technique, which combines high-strength near surface mounted bars with a fiber reinforced polymer wrapping system. This study presents the full-scale shaker testing of a non-ductile frame structure retrofitted using the combined retrofit system. The full-scale dynamic testing was performed to measure realistic dynamic responses and to investigate the effectiveness of the retrofit system through the comparison of the measured responses between as-built and retrofitted test frames. Experimental results demonstrated that the retrofit system reduced the dynamic responses without any significant damage on the columns because it improved flexural, shear and lap-splice resisting capacities. In addition, the retrofit system contributed to changing a damage mechanism from a soft-story mechanism (column-sidesway mechanism) to a mixed-damage mechanism, which was commonly found in reinforced concrete buildings with strong-column weak-beam system.

• The Transactions of the Korea Information Processing Society
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• v.6 no.9
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• pp.2384-2392
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• 1999

Software engineers are used to analyse the error behavior of computer programs using test cases which are collected for the testing phase when software errors are detected. In actual software testing and debugging, it is important to adopt dynamic slicing technique which is concerned on all the statements to be affected by the variables of current inputs and to use technique of its implementations. The traditional dynamic slicing has focused on the single slicing criterion algorithm. It has been thought that it is needed to develope and implement algorithm for used multiple criteria variables program slicing, which finds every slicing criterion variable where it is used multiple criteria variables. In this paper, we propose an efficient algorithm to make dynamic program slices when it has used multiple criteria variables. The results of the implementation are presented by the making table on execution history and the dynamic dependence graph. Also we can find that the proposed dynamic program slicing approach using multiple criteria variables is more efficient than the traditional single case algorithm on the practical testing environment.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.11 no.3
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• pp.1393-1405
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• 2017

It is well known that duty-cycling control by dynamically adjusting the polling interval according to the traffic loads can effectively achieve power saving in wireless sensor networks. Thus, there has been a significant research effort in developing polling interval adaptation schemes. Especially, Dynamic Low Power Listening (DLPL) scheme is one of the most widely adopted open-looping polling interval adaptation techniques in wireless sensor networks. In DLPL scheme, if consecutive idle (busy) samplings reach a given fixed threshold, the polling interval is increased (decreased). However, due to the trial-and-error based approach, it may significantly deteriorate the system performance depending on given threshold parameters. In this paper, we propose a novel DLPL scheme, called SDL (Sequential hypothesis testing based Dynamic LPL), which employs sequential hypothesis testing to decide whether to change the polling interval conforming to various traffic conditions. Simulation results show that SDL achieves substantial power saving over state-of-the-art DLPL schemes.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.11
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• pp.34-41
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• 2001

This study is to investigate the energy absorption characteristics of CFRP(Carbon-Fiber Reinforced Plastics) tubes on static and dynamic tests. Axial static compression tests have been carried out using the static testing machine(Shin-gang buckling testing machine) and dynamic compression tests have been utilized using an vertical crushing testing machine. When such tubes are subjected to crushing loads, the response is complex and depends on the interaction between the different mechanisms that could control the crushing process. The collapse characteristics and energy absorption have been examined for various tubes. Energy absorption of the tubes are increased as changes in the lay-up which may increase the modulus of tubes. The results have been varied significantly as a function of ply orientation and interlaminar number.

• Proceedings of the Korean Reliability Society Conference
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• 2000.11a
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• pp.87-95
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• 2000

The testing product is the HSU(Hydrostatic Steering Unit) installed in the armored vehicle which has the compact structure of assembly with hydraulic pump, hydraulic motor, and several hydraulic valves. There are no assesment testing code for HSU within a country because the testing code for HUS is not involved in the technical concert from USA. Therefore the testing code is developed by the dynamic analysis of the armored vehicle. By the developed testing code, the test equipment is designed, manufactured, and used to apply the assesment test.

• International Journal of Internet, Broadcasting and Communication
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• v.9 no.3
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• pp.70-77
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• 2017

Dynamic visual acuity is used as an important factor to measure athletic performance in sports field. A study on visual acuity testing system using non-see head mounted display (NST-HMD) was conducted recently. However, the NST-HMD has a problem that the sense of space felt by the subject differs from the actual environment. This is because the view is blocked so that it is only implemented in a virtual space. This paper proposes a dynamic visual acuity testing system using optical see through head mounted display (OST-HMD). To do this, OST-HMD and NST-HMD comparative tests were conducted using existing K-D (King-Devick) charts. Experiments were performed on 30 subjects and their visual acuity was measured and analyzed by parametric statistics and one-sample T-test. The results of the study demonstrate the effectiveness of the proposed OST-HMD. This study is expected to use the visual inspection and training equipment of OST-HMD.