• Journal of the Architectural Institute of Korea Structure & Construction
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• v.34 no.12
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• pp.73-82
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• 2018

The objective of this study was to evaluate particle collection performance of electrostatic precipitator (ESP) integrated with double skin façade in naturally ventilated residential buildings using numerical method. To evaluate the efficiency, computational fluid dynamics (CFD) simulation based on electric potential and Lagrangian method was applied. The CFD model was validated by comparing the simulated results with the experimental data including thermal characteristic of double skin façade (DSF) and particle removal characteristic of electrostatic precipitator. The validation results showed that the root mean square error (RMSE) between predicted values and measured values of velocity and temperature in intermediate space of DSF was 1.2%. The adequacy of ion space charge density and turbulent model were determined. The RMSE between predicted values and measured values of collection efficiency of ESP was 9.2%. In addition, the case study was performed to present the application of the numerical method based on validation results of ESP integrated with façade.

• Journal of the Korea Computer Graphics Society
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• v.25 no.2
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• pp.11-18
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• 2019

In this paper, we propose a framework that can perform acceleration collision detection efficiently by using a cone based collision area in a particle-based system which requires collision detection with many objects. Three conditions determine particle and cone-based collision regions: 1) If there is a cone position within the radius of the adjacent particle, 2) In the case where the position of the adjacent particle exists in the cone area, 3) When adjacent particles exist between two vectors forming a cone area. As a result, it is defined that when the above conditions are all satisfied, the particle and the region of a cone have collided. In this paper, we automatically update the area of the cone, which is the collision detection area, according to the particle movement. Determine the direction and length of the cone based on the position and velocity of the particle to calculate the dynamic change of the cone. Collision detection is performed quickly using only the particles in the finally calculated area. The acceleration method proposed in this paper is simple to implement because it is executed with a closed form equation instead of explicitly creating the tree data structure, and collision inspection performance is improved in all results.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.26 no.3
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• pp.367-376
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• 2016

Objectives: The production and use of nanoparticles have been increased. In 2014 Workplace Survey Results, 335 companies produce and treat nanoparticls. However, lack of data on nano-toxicity and a method for risk management and regulation on nanoparticles and the standard test method are not sufficient. Protective equipment selection guidelines for nanoparticles are not established. It is required to carry out respirator efficiency test against nanoparticles. This study was performed to evaluate filtration efficiency and manikin-based total inward leakage of particle filtering mask using in Korean country challenged with silver nanoparticles. Methods: We investigated filtration efficiency and total inward leakage of 7 respirator with silver nanoparticle. Results: The geometric mean diameters of Silver nanoparticles were 30 nm and number concentration were about $10^6{\sharp}/cm^3$. Filtration efficiency of six of the seven particle filtering masks was more than 98% and one particle filtering masks filtration efficiency was 94.9%. The filtration efficiency of particle filtering masks to 20 nm silver nanoparticels was highest. Artificial breathing machine with manikin based total inward leakage were 7.6% ~ 42.3%. Conclusions: The results of this study nano-silver filter efficiency was high but the total inward leakage was higher than filter penetration. Therefore, education on how to wear a respirator should be demanded. Especially for workers handling nanoparticles and toxic material, user seal checking and fit test must be performed.

• Particle and aerosol research
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• v.10 no.4
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• pp.163-167
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• 2014

Particle number portable emission measurement system (PN-PEMS) is an instrument for measuring number concentration of automobile exhaust. The principle of some pre-existing commercial PN-PEMS is to charge particles and display the number of particles by measuring current. However, this method has some problems for measuring exhaust. In this study, to solve these issues, we have developed a single particle counting PN-PEMS based condensation particle counter (CPC). The PN-PEMS based CPC does not affect driving conditions and it is convenient for mobile because the instrument is small and light in structure. We evaluated counting efficiency of PN-PEMS based CPC by using electrostatic method (electrometer and Faraday cup).

• Structural Engineering and Mechanics
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• v.83 no.5
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• pp.593-607
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• 2022

To solve the problem of detecting structural damage, a two-stage method using the Kalman filter and Particle Swarm Optimization (PSO) is proposed. In this method, the first PSO population is enhanced using the Kalman filter method based on dynamic responses. Due to noise in the sensor responses and errors in the damage detection process, the accuracy of the damage detection process is reduced. This method proposes a novel approach for solve this problem by integrating the Kalman filter and sensitivity analysis. In the Kalman filter, an approximate damage equation is considered as the equation of state and the damage detection equation based on sensitivity analysis is considered as the observation equation. The first population of PSO are the random damage scenarios. These damage scenarios are estimated using a step of the Kalman filter. The results of this stage are then used to detect the exact location of the damage and its severity with the PSO algorithm. The efficiency of the proposed method is investigated using three numerical examples: a 31-element planer truss, a 52-element space dome, and a 56-element space truss. In these examples, damage is detected for several scenarios in two states: using the no noise responses and using the noisy responses. The results show that the precision and efficiency of the proposed method are appropriate in structural damage detection.

• International Journal of Control, Automation, and Systems
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• v.4 no.6
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• pp.775-781
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• 2006

An intelligent optimization method for designing Fractional Order PID(FOPID) controllers based on Particle Swarm Optimization(PSO) is presented in this paper. Fractional calculus can provide novel and higher performance extension for FOPID controllers. However, the difficulties of designing FOPID controllers increase, because FOPID controllers append derivative order and integral order in comparison with traditional PID controllers. To design the parameters of FOPID controllers, the enhanced PSO algorithms is adopted, which guarantee the particle position inside the defined search spaces with momentum factor. The optimization performance target is the weighted combination of ITAE and control input. The numerical realization of FOPID controllers uses the methods of Tustin operator and continued fraction expansion. Experimental results show the proposed design method can design effectively the parameters of FOPID controllers.

• 한국전산유체공학회:학술대회논문집
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• 2011.05a
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• pp.278-285
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• 2011

In the present study, the numerical prediction of the oil amount leaked from the hole of a damaged tank is investigated using the improved MPS (Moving Particle Semi-implicit) method, which was originally proposed by Koshizuka and Oka (1996) for incompressible flow. The governing equations, which consist of the continuity and Navier-Stokes equations, are solved by Lagrangian moving particles, and all terms expressed by differential operators should be replaced by the particle interaction models based on a Kernel function. The simulation results are validated though the comparison with the analytic solution based on Torricelli's equilibrium relation. Furthermore, a series of numerical simulations under the various conditions are performed in order to estimate more accurately the initial amount of leaked oil.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2007.06a
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• pp.53-54
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• 2007

Charged particle type display using particles which have opposite charge and color is based on effect of reversible optical property due to electric field. we designed mask pattern for fabrication of the charged particle type display based on glass substrate and investigated cell gap dependent of driving voltage and selectively driving method. the panel driven by our selectively driving method, we could obtain image which had vary little crosstalk caused by electrical interference and conform the last image maintained by memory effect without additional voltage.

• Ocean Systems Engineering
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• v.7 no.3
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• pp.299-318
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• 2017

The paper aims at illustrating several key issues and ongoing efforts for development of a reliable fully-Lagrangian particle-based solver for simulation of hydroelastic slamming. Fluid model is founded on the solution of Navier-Stokes along with continuity equations via an enhanced version of a projection-based particle method, namely, Moving Particle Semi-implicit (MPS) method. The fluid model is carefully coupled with a structure model on the basis of conservation of linear and angular momenta for an elastic solid. The developed coupled FSI (Fluid-Structure Interaction) solver is applied to simulations of high velocity impact of an elastic aluminum wedge and hydroelastic slammings of marine panels. Validations are made both qualitatively and quantitatively in terms of reproduced pressure as well as structure deformation. Several remaining challenges as well as important key issues are highlighted. At last, a recently developed multi-scale MPS method is incorporated in the developed FSI solver towards enhancement of its adaptivity.

• Proceedings of the IEEK Conference
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• 2009.05a
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• pp.210-212
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• 2009

In object tracking based on the particle filter algorithm controlling the proper distribution of the samples is essential to accurately track the target. If the samples are spread too wide compared to the target size, the tracking accuracy may degrade as some samples can be caught by background clutters that is similar to the target. On the other hands if the samples are spread too narrow, the particle filter may fail to track the abrupt motion of the target. To solve this problem we propose an improved particle filter that adopts "re-weighting" technique at the observe step. We estimate the distribution of the weights of the current samples by its mean and variance. Then the samples are re-weighted so that the appropriate distribution of the samples in proportional to the target scale is obtained at the next select step. The proposed tracking method can avoid convergence to local mean and improve the accuracy of the estimated target state.