• Title/Summary/Keyword: particle system

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Fume Particle Dispersion in Laser Micro-Hole Machining with Oblique Stagnation Flow Conditions (경사 정체점 유동이 적용된 미세 홀 레이저 가공 공정의 흄 오염입자 산포특성 연구)

  • Kim, Kyoungjin;Park, Joong-Youn
    • Journal of the Semiconductor & Display Technology
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    • v.20 no.3
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    • pp.77-82
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    • 2021
  • This numerical study focuses on the analysis of fume particle dispersion characteristics over the surface of target workpiece in laser micro-hole machining process. The effects of oblique stagnation flow over fume generating machining point are examined by carrying out a series of three-dimensional random particle simulations along with probabilistic particle generation model and particle drag correlation of low Reynolds number. Present computational model of fume particle dispersion is found to be capable of assessing and quantifying the fume particle contamination in precision hole machining which may influenced by different types of air flow patterns and their flow intensity. The particle size dependence on dispersion distance of fume particles from laser machining point is significant and the effects of increasing flow oblique angle are shown quite differently when slot blowing or slot suction flows are applied in micro-hole machining.

Dispersion Characteristics of Nonspherical Fume Micro-Particles in Laser Line Machining in Terms of Particle Sphericity (입자 구형도에 따른 레이저 선가공의 비구형 흄 마이크로 입자 산포 특성 연구)

  • Kim, Kyoungjin;Park, Joong-Youn
    • Journal of the Semiconductor & Display Technology
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    • v.21 no.2
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    • pp.1-6
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    • 2022
  • This computational investigation of micro-sized particle dispersion concerns the fume particle contamination over target surface in high-precision laser line machining process of semiconductor and display device materials. Employing the random sampling based on probabilistic fume particle generation distributions, the effects of sphericity for nonspherical fume particles are analyzed for the fume particle dispersion and contamination near the laser machining line. The drag coefficient correlation for nonspherical particles in a low Reynolds number regime is selected and utilized for particle trajectory simulations after drag model validation. When compared to the corresponding results by the assumption of spherical fume particles, the sphericity of nonspherical fume particles show much less dispersion and contamination characteristics and it also significantly affects the particle removal rate in a suction air flow patterns.

Validation Experiments for a Holographic Particle Velocimetry System (펄스 홀로그래프를 이용한 입자 속도 측정 시스템의 검증 실험)

  • Oh, Dai-Jin;Choo, Yeon-Jun;Kang, Bo-Seon
    • Proceedings of the KSME Conference
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    • 2001.06e
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    • pp.714-719
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    • 2001
  • The Holographic Particle Velocimetry system can be a promising optical tool for the measurements of three dimensional particle velocities. In this research, the optical system for double pulse holographic recording and reconstruction of particle images was developed. Validation experiments for the developed system were conducted measuring the velocities of glass beads on a rotating disk. Uncertainty analysis was performed to identify the sources of all relevant errors and to evaluate their magnitude. The measurement results of distance between glass beads, size, and velocities of them using holographic method compared reasonalbly well with the known values within acceptable range of errors.

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Simulation of Sediment Transport in a River System Using Particle Entrainment Simulator (페즈(PES)를 이용한 하천의 토사 이동 시뮬레이션)

  • Lee, Young-Soo
    • Journal of Korean Society of Water and Wastewater
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    • v.18 no.1
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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.

Small Particle Detection System by Optical Scattering Effect (광 산란특성을 이용한 미세입자 감지시스템)

  • Kim, Eung-Soo
    • The Journal of the Korea institute of electronic communication sciences
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    • v.7 no.3
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    • pp.579-583
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    • 2012
  • We have designed the small particle detection system. The scatteing effect of light was used to detect small particle. The fabricated system consisted of laser diode, lens, pin hole, and photo detector. The aperture, lens, and photo detector were optimized to improve the performance of detection system. The fabricated detection system detected the scattered light by small particle entering into detection system and its response time was fast.

Particle Swarm Optimization for Redundancy Allocation of Multi-level System considering Alternative Units (대안 부품을 고려한 다계층 시스템의 중복 할당을 위한 입자 군집 최적화)

  • Chung, Il Han
    • Journal of Korean Society for Quality Management
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    • v.47 no.4
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    • pp.701-711
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    • 2019
  • Purpose: The problem of optimizing redundancy allocation in multi-level systems is considered when each item in a multi-level system has alternative items with the same function. The number of redundancy of multi-level system is allocated to maximize the reliability of the system under path set and cost limitation constraints. Methods: Based on cost limitation and path set constraints, a mathematical model is established to maximize system reliability. Particle swarm optimization is employed for redundant allocation and verified by numerical experiments. Results: Comparing the particle swarm optimization method and the memetic algorithm for the 3 and 4 level systems, the particle swarm optimization method showed better performance for solution quality and search time. Particularly, the particle swarm optimization showed much less than the memetic algorithm for variation of results. Conclusion: The proposed particle swarm optimization considerably shortens the time to search for a feasible solution in MRAP with path set constraints. PS optimization is expected to reduce search time and propose the better solution for various problems related to MRAP.

Particle Agglomeration of a Bipolar Charging System with a Control Grid (제어전극을 갖는 쌍극성 하전장치의 입자응집 특성)

  • Moon, Jae-Duk;Ahn, Chang-Jin
    • The Transactions of the Korean Institute of Electrical Engineers C
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    • v.54 no.10
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    • pp.465-470
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    • 2005
  • In this paper. an experimental study, for method of increasing the efficiency of electrostatic precipitator for the collection of submicron-sized particles has been studied. All AC electric field was used to induce agglomeration of bipolory charged Particles. .4 bipolar AC-agglomeration system. consisted with a multineedle-mesh discharge system with a control grid, was proposed and investigated. Systematic experiments were carried out to investigate the agglomeration ratio of the AC-agglomeration system as a function of the different grid spacings and grid resistances for the submicron particles generated from liquid prorhane gas burning. The agglomeration ratios, which indicate the particle numbers before and after agglomeration of the test particles in number concentration base, were found to be 0.87, 1.80, 3.86, 9.50 and, 11.00 times for the particle sizes of 0.3. 0.5, 0.7, 1.0, and 2.0$\mu$m at applied voltage of 3.5kV, respectively which showed that the fine particle numbers were decreased while the larger particle numbers were increase greatly.

Influence of Aftertreatment System on the Size Distribution of Diesel Exhaust Particulate Matter (후처리 장치에 의한 디젤엔진 배출가스의 미세 입자 입경분포 변화)

  • 권순박;김민철;이규원;류정호;엄명도;김종춘;정일룩
    • Transactions of the Korean Society of Automotive Engineers
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    • v.7 no.7
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    • pp.113-121
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    • 1999
  • Diesel particulate matter is known to be one of the major harmful emissions produced by diesel engines. Diesel particulates are subject to diesel emission regulations and have lately become the focus in the diesel emission control technology. Thus, the aftertreatment system is adopted at the diesel engine exhaust to reduce the particulate emission. Although this benefit is recognized, it is not clear how the aftertreatment system influences quantitatively the particle size distribution distribution. In this study, the particle size distributions of diesel exhaust were measured using the scanning mobility particle sizer with and without the aftertreatment system. There results showed that the diesel particulate filter and plasm system reduced the number of emitted particles by more than 90% and about 80% respectivley in the particle size range of 20nm∼600nm. On the other hand no significant effect of the diesel oxidation catalyst on the particle number concentration was detected.

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Development and Performance Test of In-situ Particle Monitoring System using Ion-counter in Vacuum Environments (진공 환경내 실시간 입자 모니터링 시스템의 개발 및 성능평가)

  • Ahn Kang-Ho;Kim Yong-Min;Kwon Yong-Taek
    • Journal of the Semiconductor & Display Technology
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    • v.5 no.1 s.14
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    • pp.45-49
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    • 2006
  • In this paper, a new method that monitors the quantity of particles using ion-counter in vacuum environment is introduced. In-situ particle monitoring (ISPM) system is composed by Gerdien type ion-counter (house-made), DC power supply and electrometer. The ion-counter applied by positive voltage detects only positive charged particles. Therefore the particles to be detected should be in known charge state for further data analysis. ion-counter is installed at the exhaust line of process equipment where the pressure loss is structurally low. ISPM system performance has been verified with SMPS (Scanning Mobility Particle Sizer) system. The correlation coefficient is above 0.98 at the particle size range of $20{\sim}300nm$ in diameter with identified charge distribution under $0.1{\sim}10.0$ Torr.

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Effect of Specific Interaction of Multi-Ligands on the Specific Interaction between Particle and Cell (멀티 리간드의 특이적 상호작용이 입자-세포간 상호작용에 미치는 영향)

  • Yoon, Jung Hyun;Lee, Sei Young
    • Journal of Biomedical Engineering Research
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    • v.43 no.2
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    • pp.94-101
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    • 2022
  • Recent advancement of micro/nano technology enables the development of diverse micro/nano particle-based delivery systems. Due to the multi-functionality and engineerability, particle-based delivery system are expected to be a promising method for delivery to the target cell. Since the particle-based delivery system should be delivered to the various kinds of target cell, including the cardiovascular system, cancer cell etc., it is frequently decorated with multiple kinds of targeting molecule(s) to induce specific interaction to the target cell. The surface decorated molecules interact with the cell surface expressed molecule(s) to specifically form a firm adhesion. Thus, in this study, the probability of adhesion is estimated to predict the possibility to form a firm adhesion for the multi-ligand decorated particle-based delivery system.