• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.1
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• pp.218-224
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• 2013

Generally, SAW device, which uses Time Domain Sampling, requires high speed A/D converter because SAW device using TDS needs high sampling speed as much as its high data speed. However, the high price of A/D converter discourages makers from using it. On the other hand, SAW device, which uses Frequency Domain Sampling, does not required high speed A/D converter because SAW device using FDS does not need high sampling speed. It is very efficient in price comparison to its performance because high processing speed of SAW device using FDS can be implemented using low price Embedded Systems. The purpose of the paper is to solve the issues above by designing and realizing SAW device(FDS) using SAW sensor for TDS.

• Fire Science and Engineering
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• v.31 no.4
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• pp.35-42
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• 2017

Large Eddy Simulation (LES) was peformed for the backdraft occurred in a compartment filled with high-temperature methane fuel using the Fire Dynamics Simulator (FDS) of version 6. The prediction performance of FDS, adopted the Eddy Dissipation Concept (EDC) combustion model with five different chemical reaction mechanisms, was evaluated. The temporal distributions of temperature, fuel mass fraction, velocity and pressure were discussed with numerical results and the pressure variation in time was compared with that of previous experiment. The FDS adopted the EDC model showed the possibility of LES for the backdraft phenomena. However, the prediction performance of the LES with EDC model strongly depended on the chemical reaction mechanism considered. It is necessary that the suitability of the chemical reaction mechanism should be validated in advance for LES with the FDS v6 to be applied to the simulation of backdraft.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.1594-1600
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• 2011

Recently developed FDS5 CFD code has employed a near-wall flow treatment method which is Werner-Wengle wall law provided by NIST(National Institute of Standards and Technology). In this study, the wall law has been verified against DNS(Direct Numerical Simulation) data in the parallel plate. The $y^+$ was kept above 11 to fulfill the near-wall flow requirement in the grid generation. The total grid was $32{\times}32{\times}32$. The boundary condition for inlet and outlet was periodic condition and for both side, symmetric condition was used. The fully developed turbulent flow was generated and Re = 10,700. The simulated results were compared with DNS data. RANS results were also used for verification.

• Journal of the Korean Society of Safety
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• v.25 no.3
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• pp.22-27
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• 2010

A prediction performance of Fire Dynamics Simulator(FDS) developed by NIST for the diffusion flame structure was validated with experimental results of a laminar slot jet diffusion flame. Two mixture fraction combustion models and two finite chemistry combustion models were used in the FDS simulation for the validation of the jet diffusion flame structure. In order to enhance the prediction performance of flame structure, DNS and radiation model was applied to the simulation. The reaction rates of the finite chemistry combustion models were appropriately adjusted to the diffusion flame. The mixture fraction combustion model predicted the diffusion flame structure reasonably. A 1-step finite chemistry combustion model cannot predict the flame structure well, but the simulation results of a 2-step model were in good agreement with those of experiment except $CO_2$ concentration. It was identified that the 2-step model can be used in the investigation of flame suppression limit with further adjustment of reaction rates

• Smart Structures and Systems
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• v.6 no.4
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• pp.363-372
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• 2010

Accurate peak response estimation of a seismically excited structure with frictional damping system (FDS) is very difficult since the structure with FDS shows nonlinear behavior dependent on the structural period, loading characteristics, and relative magnitude between the frictional force and the excitation load. Previous studies have estimated the peak response of the structure with FDS by replacing a nonlinear system with an equivalent linear one or by employing the response spectrum obtained based on nonlinear time history and statistical analysis. In case that earthquake excitation is defined probabilistically, corresponding response of the structure with FDS becomes to have probabilistic distribution. In this study, nonlinear time history analyses were performed for the structure with FDS subjected to artificial earthquake excitation generated using Kanai-Tajimi filter. An equation for the probability density function (PDF) of the displacement response is proposed by adapting the PDF of the normal distribution. Coefficients of the proposed PDF are obtained by regression of the statistical distribution of the time history responses. Finally, the correlation between the resulting PDFs and statistical response distribution is investigated.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.33 no.3
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• pp.156-163
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• 2009

In this study, comparative analysis on the back-layer phenomena in the tunnel-fire driven flow is performed using numerical simulation with LES and RANS. FDS(Fire Dynamics Simulator) code is employed to calculate the fire-driven turbulent flow for LES and Smartfire code is used for RANS. Hwang and Wargo's data of scaling tunnel fire experiment are employed to compare with the present numerical simulation. The modeled tunnel is 5.4m(L) ${\times}$ 0.4m(W) ${\times}$ 0.3m(H). Heat Release Rate (HRR) of fire is 3.3kW and ventilation-velocity is 0.33m/s in the main stream. The various grid-distributions are systematically tested with FDS code to analyze the effects of grid size. The LES method with FDS provides an improved back-layer flow behavior in comparison with the RANS (${\kappa}-{\epsilon}$) method by Smartfire. The FDS solvers, however, overpredict the velocity in the center region of flow which is caused by the defects in the tunnel-entrance turbulence strength and in the near-wall turbulent flow in FDS code.

• Journal of the Korea Safety Management & Science
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• v.11 no.2
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• pp.77-85
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• 2009

Considering heat insulation and beautiful sight of construction, making use of exterior panels is increasing. Recently the exterior panels now are weak very much, and so in consequence of the weakness fire spreads rapidly. Compared with internal fire, external vertical fire spread rate goes rapidly and it is extensive in spread range, therefore it is dangerous very much. Accordingly, under present condition of poor standard of exterior panels, it is required to take measure to meet the appropriate situation. In this study, by making use of FDS(Fire Dynamic Simulation) program about external vertical fire of high rise building, fire behavior is searched by computer. It is important that realizing by computer fire modeling about external vertical fire must be included certainly in procedure of fire performance design in the future. In modeling program, FDS version 5 is available, and aluminium composite panel is applied in external panels. In this study, for realizing of actual fire condition, FDS is applied by details of fire scenarios considering influence of wind.

• Fire Science and Engineering
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• v.26 no.2
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• pp.40-52
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• 2012

This paper presents the uncertainty analysis results of fire modeling input parameters for motor control center in switchgear room of nuclear power plants. FDS (Fire Dynamics simulator) 5.5 was used to simulate the fire scenario and Latin Hyper Cube Monte Carlo simulations were employed to generate random samples for FDS input parameters. The uncertainty analysis results of input parameters are compared with those of the model uncertainty analysis and sensitivity analysis approaches of NUREG-1934. The study results show that the input parameter uncertainty analysis approach may lead to more conservative results than the uncertainty analysis and sensitivity analysis methods of NUREG-1934.

• Proceedings of the SAREK Conference
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• 2008.06a
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• pp.1332-1337
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• 2008

Fire model shall be verified and validated to reliably predict the consequences of fires within its limitations. This study aims to predict pool fire with two rooms using FDS and to coompare FDS simulation results with PRISME experimental data which can be applicable to the fire of nuclear power plant facility. Four different sizes of grid (0.08m, 0.1m, 0.125m, 0.2m) are used in the simulation and the simulated results of specific quantities such as temperature, chemical composition, heat flux and heat release rate are compared to the experimental data. From this study, the FDS simulation results with the finer grid resolution show better similarity and trend with pool fire experimental data. The sensitivity analysis and the selection of the proper size grid are essential to predict the consequences of pool fire with two rooms reliably.

• Physical Therapy Korea
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• v.14 no.3
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• pp.9-15
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• 2007

The purpose of this study was to investigate electromyographic activities of the flexor digitorum superficialis (FDS) and the flexor carpi ulnaris (FCU) by the shape of the ultrasound head. Twelve healthy subjects participated and performed ultrasound therapy with a round head and a long handled head during each 5-minute application. Electromyographic activities of the FDS and FCU were recorded by surface electrodes and normalized by maximal voluntary isometric contraction (MVIC) values. There was no difference in the muscular fatigue of FDS and FCU as determined by the shape of the ultrasound head (p>.05). Without the shape of head, the mean power frequency decreased with the time. There also was no difference in %MVIC of the FDS and FCU as determined by the shape of the ultrasound head (p>.05), but the force exerted exceeded 20%MVIC. There was however a significant difference in the amount of cumulative workload of the FDS and FCU as determined by the shape of ultrasound head (p<.05). The workload was however not affected by the shape of the ultrasound head. Constant static grasp of ultrasound transducer head during ultrasound therapy is considered a high risk factor of work-related musculoskeletal disease.