• 대한기계학회논문집B
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• 제25권12호
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• pp.1802-1812
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• 2001

The purpose of this study is to analyze numerically the movement of particles included in turbulent fluid flow characteristics of metallic surfaces. To describe fluid flew, the incompressible Navier-Stokes equation discretized by the finite volume method were solved on the non-orthogonal coordinates with non-staggered variable arrangement, and the k-$\xi$ turbulence model was adapted. After fluid flow was calculated, particle movement was predicted from the Lagrangian approaches. Non-essential complexities were avoided by assuming that the particles had spherical shapes and the Stoke's drag formula only consisted of external farces acting upon them. In order to validate the numerical calculations, the results were compared with the experimental data reported in literature and agreed well with them. The drag force coefficient equation showed better agreement with the experimental data in the prediction of particle movement than the correction factor equation. Impact velocity and impact angle increased as inlet turbulence intensity decreased, relative jet height was lower. or the Reynolds number was larger.

• International journal of advanced smart convergence
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• 제10권3호
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• pp.157-162
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• 2021

With the recent increase in YouTube content, many YouTubers are shooting with a handheld camera. Audiences are increasingly accustomed to the movement of handheld cameras. As the camera moves faster than the camera movement of the old movies, and the camera moves splendidly to the music of the music video, the camera movement in CG animation is also needed to change. The handheld Steadicam creates a natural camera movement by compensating so that the screen does not vibrate significantly even when the vibration is large and by minimizing rotation. In order to implement such camera movement, we tried to make a handheld Steadicam using nParticle simulation of Maya software and apply it to the scene to verify whether it is possible to implement the necessary natural and various movement.

• 한국지반공학회지:지반
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• 제13권5호
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• pp.155-168
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• 1997

흙 세립자의 이탈 및 유동은 지반공학이나 지반환경공학적인 관점에서 매우 중요한 현상 중의 하나이다. 특히 지반환경공학적인 견지에서 보면 세림자가 입자유동을 하기 전에 오염물질을 흡착하기 때문에, 오염물질 정화의 방편으로 이용될 수 있다. 본 논문에서는 한국에 가장 편재해 있는 화강풍화토의 입자유동특성을 실내시험에 의해 파악하였다. 실험에 사용된 시료는 대표적인 잔류토라 할 수 있는 서을 신내동, 포이동 및 경북 안동의 시료 각각에 대하여 흐름에 대한 지반특성 치등을 측정하였다. 풍화잔적토에서의 세립분 유동특성에 가장 큰 영향을 미차는 인자는 세립자의 함량과 초기간극률 그리고 입도분포로 나타났고 입자가 이탈되기 시작하는 한계속도는 200번체 통과량에 비례 하여 감소하는 경향을 보였다. 이탈률의 변화율은 간극률에 비례하여 증가함을 보였으며 입도분 포가불량하고200번체 통과량이 적은 시료에서의 입자이탈량이 가장 크게 나타났다. 또한 실험결과를 토대로 단계별 입자유동현상을 표현하는 기본방정식을 모델링하고 유한차분법을 이용하여 해를구하므로써 흐름이 발생하는 지반구조물에서 입자유동현상이 미치는 영향을 파악할 수 있는 토대를 마련하였다.

• 한국결정성장학회지
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• 제13권3호
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• pp.145-151
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• 2003

전산유체역학을 이용하여 전형적인 구조를 갖는 사이클론 분리기 시스템 내에서의 주입 가스 유동 및 입자 거 동해석을 통해 가스 주입 유속에 따른 입자 거동 양상을 3차원적으로 해석하였다. 해석 결과는 Navier-stokes 방정식을 이용한 유체 유동 현상과 Lagrangian 접근법을 이용한 입자 거동 경로 추적을 결합시켜 도출되었다. 주입 유속이 증가함에 따라 내부 압력 손실이 증가하였고 이런 내부 압력 변화는 분리기 내의 유체의 유동 양상에 영향을 미쳤다. 입자의 거동은 유체의 유동에 의해 결정되었으며 일정 유속에 대해서는 입자의 크기에 크게 의존하였다. 그리고 주입 유속의 증가는 입자의 경로를 증가시키면서 분리기의 하부 영역으로 이동시켰다. 이로 인해 분리기내에 존재하는 입자의 최소 크기가 작아지며 일정 크기의 입자의 경우 분리율이 증가하였다. 결론적으로 가스 유입 유속의 변화는 내부의 유체 유동 변화와 입자 거동 양상에 중요한 요인이 된다.

• 한국대기환경학회지
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• 제12권3호
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• pp.243-254
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• 1996

The main purpose of this study is to investigate the collection efficiency characteristics of a cylindrical ESP. To do that, it is necessary to analyze the electric field, gas flow field, and mechanism of particle movement by numerical simulation based on EHD model. For a gas flow field, Navier-Stokes equation involving the electric source term was solved by SIMPLE algorithm. In case of the electric field, the current continuity and electric field equations were solved by S.O.R. method. The analysis of particle movement was performed on the basis of PSI-CELL model from the Lagrangian viewpoint. The results showed that the influence on the gas flow field by the electric field is almost negligible in a cylindrical ESP. The particle drift velocity $V_P$ toward the collection surface is increased continuously by the electrostatic force due to the rise of particle charge as the particle is moving to the flow direction and the particle size becomes larger. The collection efficiency is to quitely higher with the increase of applied voltage for the same particle size, while becomes smaller as the inlet velocity is increased.

• 한국지능시스템학회논문지
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• 제19권4호
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• pp.586-591
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• 2009

본 논문에서는 Particle filter를 이용한 특징 벡터 기반 이동 물체 추적 알고리즘을 제안한다. 이를 위해, 첫 번째, RGB 칼라 모델을 이용하여 초기 이동 물체의 움직임 영역(blob)을 추출하고, KLT-알고리즘을 이용하여 입력 영상에 대한 특징 벡터를 구한다. 그 다음, 초기 추출된 이동 물체의 움직임 영역에 이 특징 벡터를 매칭시켜 1차 특징 벡터를 구한다. 두 번째로, RGB와 HSI 칼라모델을 이용하여 이동 물체의 움직임 영역을 추출하고, 앞서 구한 1차 특징 벡터에 Snake 알고리즘을 적용함으로써 새로운 특징 벡터를 구한다. 그 다음, 기 추출된 이동 물체의 움직임 영역에 이 새롭게 구한 특징 벡터를 매칭시켜 2차 특징 벡터를 구한다. 최종적으로, 2차 특징 벡터에 Particle filter를 적용함으로써 본 논문에서 제안한 이동물체를 추적하는 알고리즘을 완성한다. 마지막으로, 본 논문에서 제안한 알고리즘은 복잡하고 다양한 환경에서 실험을 통해 그 응용 가능성을 증명한다.

• 상하수도학회지
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• 제18권1호
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• pp.5-14
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• 2004

A feasibility of using Particle Entrainment Simulator (PES) to evaluate model variables describing sediment entrainment in a river system was investigated. PES in a laboratory was utilized to simulate the sediment resuspension phenomenon in the river and the subsequent relationship between shear rate and sediment entrainment was developed. The total suspended solids (TSS) data from PES was incorporated into statistical models in an effort to describe behaviors of net particle movement in the river. PES was found to be adequate for simulating particle entrainment phenomenon in a river system. Statistical analysis was used to assess propriety of PES data for predictive purposes. The results showed good relationships between PES results and system variables, such as average stream velocity and net particle movement.

• ETRI Journal
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• 제35권6호
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• pp.1168-1171
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• 2013

We propose an improvement of particle swarm optimization (PSO) based on the stabilization of particle movement (PM). PSO uses a stochastic variable to avoid an unfortunate state in which every particle quickly settles into a unanimous, unchanging direction, which leads to overshoot around the optimum position, resulting in a slow convergence. This study shows that randomly located particles may converge at a fast speed and lower overshoot by using the proportional-integral-derivative approach, which is a widely used feedback control mechanism. A benchmark consisting of representative training datasets in the domains of function approximations and pattern recognitions is used to evaluate the performance of the proposed PSO. The final outcome confirms the improved performance of the PSO through facilitating the stabilization of PM.

• Journal of Mechanical Science and Technology
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• 제19권4호
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• pp.1027-1035
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• 2005

Thermophoresis in dense gases is studied by using a multi-scale approach and Born- Yvon­Green (BYG) equation. The problem of a particle movement in an ambient dense gas under temperature gradient is divided into inter and outer ones. The pressure gradient in the inner region is obtained from the solutions of BYG equation. The velocity profile is derived from the conservation equations and calculated using the pressure gradient, which provides the particle velocity in the outer problem. It is shown that the temperature gradient applied to the quiescent ambient gas induces some pressure gradient and thus flow tangential to the particle surface in the interfacial region. The mechanism that induces the flow may be the dominant source of the thermophretic particle movement in dense gases. It is also shown that the particle velocity has a nonlinear relationship with the applied temperature gradient and decreases with increasing temperature.

• 한국전기전자재료학회논문지
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• 제25권2호
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• pp.129-134
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• 2012

We analyzed the movement and response time of charged particles according to particle-inserting methods to understand the variation of quantity of q/m of charged particles, which is a very important factor in electrical and optical characteristics of the charged particle type display, such as lifetime, response time, contrast ratio, reflectivity, etc. For our study we used white and black charged particles of which diameter is $20{\mu}m$, prepared pieces of ITO(indium tin oxide) coated glass substrate, and formed ribs on the glass substrates. The width of a rib is $30{\mu}m$ and the cell size is $220{\mu}m{\times}220{\mu}m$. As the particle-inserting methods, the white and black charged particles were respectively inserted into a front and a rear panel with a very small electric field and also the mixture of the white and black charged particles were inserted into a rear panel. As a result of the driving characteristics of charged particles, the factors about variation of quantity of q/m according to the particle inserting method was experimentally demonstrate, showing very different driving voltage, response time, the particle movement, etc.