• Transactions of the Korean Society of Mechanical Engineers B
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• v.38 no.10
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• pp.845-851
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• 2014

Dielectrophoresis (DEP) is defined as the motion of suspended particles in solvent resulting from polarization forces induced by an inhomogeneous electric field. DEP has been utilized for various biological applications such as trapping, sorting, separation of cells, viruses, nanoparticles. However, the analysis of DEP trapping has mostly employed the period-averaged ponderomotive forces while the dynamic features of DEP trapping have not been attracted because the target object is relatively large. Such approach is not appropriate for the nanoscale analysis in which the size of object is considerably small. In this study, we thoroughly investigate the dynamic response of trapping to various system parameters and its influence on the trapping stability. The effects of particle conductivity on its motion are also focused.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.14 no.1
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• pp.41-48
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• 2014

This paper analyzes the Monte Carlo localization (MCL) method, which estimates the pose of an indoor mobile robot. A mobile robot must know where it is to navigate in an indoor environment. The MCL technique is one of the most influential and popular techniques for estimation of robot position and orientation using a particle filter. For the analysis, we perform experiments in an indoor environment with a differential drive robot and ultrasonic range sensor system. The analysis uses MATLAB for implementation of the MCL and investigates the effects of the control parameters on the MCL performance. The control parameters are the uncertainty of the motion model of the mobile robot and the noise level of the measurement model of the range sensor.

• Journal of ILASS-Korea
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• v.3 no.3
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• pp.42-48
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• 1998

This study describes the spray structure of gasoline port injectors by using phase Doppler particle analyzer(PDPA) and particle motion analysis system(PMAS). The characteristics of fuel spray such as the spray penetration, spray angle and breakup processes were obtained by PMAS and the droplet size and mean velocity were measured by PDPA system. Pintle type and two-hole type injectors were used as gasoline port fuel injectors under various injection pressures. The effect of injection pressure on the droplet mean diameter and axial mean velocity of droplet were investigated under the various injection conditions. In addition the comparison of breakup processes for the two types of injectors was also conducted. It Is shown that pintle type injector has smaller droplet size than that of two-hole type injector.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.2
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• pp.193-203
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• 2014

Temperature-dependent stress analysis and heat transfer analysis of a rotating gas turbine blade made of functionally graded materials (FGMs) are presented considering turbine operating temperature and ceramic particle size. The material properties of functionally graded materials are assumed to vary continuously and smoothly across the thickness of the thin-walled blade. For obtaining system stiffness reflecting these characteristics, the one-dimensional heat transfer equation is applied along the thickness of the thin-walled blade for determining the temperature distribution. Using the results of the temperature analysis, the equations of motion of a rotating blade are derived with hybrid deformation variable modeling method along with the Rayleigh-Ritz assumed mode methods. The validity of the derived rotating blade model is evaluated by comparing its transient responses and temperature distribution with the results obtained using a commercial finite element code. The maximum tensile stress with operating speed and gradient index are obtained. Furthermore, the gradient index that minimizes blade temperature was investigated.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.05a
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• pp.15-19
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• 2006

A pulsed laser ablation deposition (PLAD) technique is an excellent method for the fabrication of amorphous carbon (a-C) films, because it can generate highly energetic carbon clusters on a substrate. This paper was focused on the understanding and analysis of the motion of C particles in laser ablation assisted by Ar plasmas. The simulation has carried out under the pressure P=50 mTorr of Ar plasmas. Two-dimensional hybrid model consisting of fluid and Monte-Carlo models was developed and three kinds of the ablated particles which are carbon atom (C), ion ($C^+$) and electron were considered in the calculation of particle method. The motions of energetic $C^+$ and C deposited upon the substrate were investigated and compared. The interactions between the ablated particles and Ar gas plasmas were discussed.

• Tunnel and Underground Space
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• v.6 no.2
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• pp.157-165
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• 1996

In order to analyze the effects of ground vibration caused by underground blasting having an effect on structure, the particle velocity and acceleration are calculated by using DYNPAK program. The DYNPAK program analyzes nonlinear transient dynamic problem and adopts the very popular and easily implemented, explicit, central difference scheme. In this program, the material behavior is assumed to be elasto-viscoplastic. Using the particle acceleration history, modal analysis method is applied to the forced vibration response of multiple-degree-of-freedom(MDOF) systems using unclupled equations of motion expressed in terms of the system's natural circular frequencies and modal damping factors. AS a means of evaluating the vibration behavior of building structure subjected to underground blasting, the time response of the displacements relative to the ground of five-story building is determined. It is concluded that the amount of explosives consumed per round, the location of structure, the properties of rock medium, the stiffness fo structure, etc. act on the important factors influencing on the safety of building and that the response of a structure subjected to a forced excitation can usually be obtained with reasonable accuracy by the modal analysis of only a few mode of the lower frequencies of the system.

• Nuclear Engineering and Technology
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• v.55 no.6
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• pp.1999-2010
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• 2023

Undesirable flapping motion of discs can cause the failure of swing check valves in nuclear passive safety systems. Time-resolved particle image velocimetry (PIV) was employed to investigate the flow characteristics around a free-to-rotate plate and the motion response, with the Reynolds numbers, based on the hydraulic diameter of the channel, from 1.32 × 10⁴ to 3.95 × 10⁴. Appreciable flapping motion (±3.52°) appeared at the Reynolds number of 2.6 × 10⁴ with the frequency of 5.08 Hz. In the low-Reynolds-number case, the plate showed negligible flapping. In the high-Reynolds-number case, the deflection angle increased with reduced flapping amplitude. The torque from the fluid determined the flapping amplitude. In the low-Reynolds-number case, Karman vortices were absent. With increasing Reynolds numbers, Karman vortices developed behind the plate with larger deflection angles. Strong interaction between the wake flow from the leading and trailing edge of the plate was observed. Based on power spectrum density (PSD) analysis, the vortex shedding frequency coincided with the flapping frequency, and the amplitude was positively correlated to the strength of the vortices. Proper orthogonal decomposition (POD) modes evince that, in the case of appreciable motion, coherent structures exhibited a larger spatial scale, enhancing the magnitude of the external torque on the plate.

• Transactions of the Korean Society of Mechanical Engineers
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• v.18 no.4
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• pp.920-932
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• 1994

The combustion phenomena of a reciprocating engine is one of the most important processes affecting performance and emissions. One effective way to improve the engine combustion is to control the motion of the charge inside a cylinder by means of optimum induction system design, because the flame speed is mainly determined by the turbulence at compression(TDC) process in S.I. engine. It is believed that the tumble and swirl motion generated during intake breaks down into small-scale turbulence in the compression stroke of the cycle. However, the exact nature of their relationship is not well known. This paper describes cycle resolved LDV measurement of turbulent flow inside the cylinder of a 4-valve engine under motoring(non-firing) conditions, and studies the effect of intake port configurations on the turbulence characteristics using following parameters ; Eulerian temporal autocorrelation coefficient, turbulence energy spectral density function, Taylor micro time scale, integral time scale, and integral length scale.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.21 no.12
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• pp.2196-2208
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• 1997

In this work, a magnetic levitation (maglev) system is developed to transport a wafer between semiconductor fabrication process modules in clean rooms to take advantages of eliminating particle and oil contamination that normally exist in conventional transport systems due to contact motion of mechanical components. A main feature of the maglev system developed in this work is that a controller and power supplying part are not mounted on the moving carrier but on the stationary track, which is defined a controller-free carrier, to reduce carrier's weight. Iron-core electromagnets and irons are used for levitation, and air-core electromagnets and permanent magnets are used for stabilization. Analysis, design, and modeling of the magnetically levitated transport system are presented. The performance of the maglev system is experimentally demonstrated.

• Journal of Ocean Engineering and Technology
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• v.33 no.2
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• pp.116-122
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• 2019

Among the various wave power systems, Salter's duck (rotor) is one of the most effective wave absorbers for extracting wave energy. The rotor shape is designed such that the front part faces the direction of the incident wave, which forces it to bob up and down due to wave-induced water particle motion, whereas the rear part, which is mostly circular in shape, reflects no waves. The asymmetric geometric shape of the duck makes it absorb energy efficiently. In the present study, the rotor was investigated using WAMIT (a program based on the linear potential flow theory in three-dimensional diffraction/radiation analyses) in the frequency domain and verified using OrcaFlex (design and analysis program of marine system) in the time domain. Then, an experimental investigation was conducted to assess the performance of the rotor motion based on the model scale in a two-dimensional (2D) wave tank. Initially, a free decay test (FDT) was carried out to obtain the viscous damping coefficient. The pitch response was extracted from the experimental time series in a periodic regular wave for two different wave heights (1 cm and 3 cm). In addition, the viscous damping coefficient was calculated from the FDT result and fluid forces, obtained from WAMIT, are incorporated into the final response of the rotor. Finally, a comparative study based on experimental and numerical results (WAMIT & OrcaFlex) was performed to confirm the performance reliability of the designed rotor.