• 제목/요약/키워드: Material Tracking

검색결과 310건 처리시간 0.022초

Numerical analysis of particle transport in low-pressure, low-temperature plasma environment

  • Kim, Heon Chang
    • 한국입자에어로졸학회지
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    • 제5권3호
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    • pp.123-131
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    • 2009
  • This paper presents simulation results of particle transport in low-pressure, low-temperature plasma environment. The size dependent transport of particles in the plasma is investigated with a two-dimensional simulation tool developed in-house for plasma chamber analysis and design. The plasma model consists of the first two and three moments of the Boltzmann equation for ion and electron fluids respectively, coupled to Poisson's equation for the self-consistent electric field. The particle transport model takes into account all important factors, such as gravitational, electrostatic, ion drag, neutral drag and Brownian forces, affecting the motion of particles in the plasma environment. The particle transport model coupled with both neutral fluid and plasma models is simulated through a Lagrangian approach tracking the individual trajectory of each particle by taking a force balance on the particle. The size dependant trap locations of particles ranging from a few nm to a few ${\mu}m$ are identified in both electropositive and electronegative plasmas. The simulation results show that particles are trapped at locations where the forces acting on them balance. While fine particles tend to be trapped in the bulk, large particles accumulate near bottom sheath boundaries and around material interfaces, such as wafer and electrode edges where a sudden change in electric field occurs. Overall, small particles form a "dome" shape around the center of the plasma reactor and are also trapped in a "ring" near the radial sheath boundaries, while larger particles accumulate only in the "ring". These simulation results are qualitatively in good agreement with experimental observation.

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곡 블록 자동화를 위한 지능형 용접 캐리지 개발 (Development of a Intelligent Welding Carriage for Automation of Curved Block)

  • 최희병;문종현;전완열;김세환
    • 대한조선학회 특별논문집
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    • 대한조선학회 2005년도 특별논문집
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    • pp.171-176
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    • 2005
  • This paper presents a novel Intelligent-Welding-Carriage (IWC) for automation of curved block in shipbuilding. The curved block is usually used in both front and back side of the ship. In curved block root gap is big, 1-7 (mm) and inclination, 0-30 (deg). Since available conventional carriage type is limited to use below root gap of 3 (mm), only manual welding is employed in curved block. To adopt an IWC in curved block, it requires control of the welding conditions, i.e., voltage. current, weaving speed, dwell time and travel speed, with respect to root gap and inclination to achieve good welding qualify. In this paper, an IWC is developed for automization of welding operation to accommodate gap and inclination. Kinematics model and dynamics using Lagrangian formulation of the manipulator is introduced. IWC utilizes a database to perform accurate welding. The database is programmed based on numerous experimental test results with respect to gap, inclination, material, travel speed, weaving condition, voltage, and current. Finally, experimental result using PID control is addressed for verifying the trajectory tracking accuracy of end-effector.

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Modelling cavitating flow around underwater missiles

  • Petitpas, Fabien;Saurel, Richard;Ahn, Byoung-Kwon;Ko, Sung-Ho
    • International Journal of Naval Architecture and Ocean Engineering
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    • 제3권4호
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    • pp.263-273
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    • 2011
  • The diffuse interface model of Saurel et al. (2008) is used for the computation of compressible cavitating flows around underwater missiles. Such systems use gas injection and natural cavitation to reduce drag effects. Consequently material interfaces appear separating liquid and gas. These interfaces may have a really complex dynamics such that only a few formulations are able to predict their evolution. Contrarily to front tracking or interface reconstruction method the interfaces are computed as diffused numerical zones, that are captured in a routinely manner, as is done usually with gas dynamics solvers for shocks and contact discontinuity. With the present approach, a single set of partial differential equations is solved everywhere, with a single numerical scheme. This leads to very efficient solvers. The algorithm derived in Saurel et al. (2009) is used to compute cavitation pockets around solid bodies. It is first validated against experiments done in cavitation tunnel at CNU. Then it is used to compute flows around high speed underwater systems (Shkval-like missile). Performance data are then computed showing method ability to predict forces acting on the system.

단일 스위치 배전압 방식의 단상 PFC 컨버터의 전류 제어기법 비교 (Comparison of Current Control Method for Single-phase PFC converter with 1-switch Voltage Doubler Strategy)

  • 구대관;지준근;차귀수;임승범;홍순찬
    • 전력전자학회논문지
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    • 제17권1호
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    • pp.1-7
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    • 2012
  • This paper describes the performance comparison results for current controller of a single-phase PFC converter with 1-switch voltage doubler strategy for single-phase double-conversion UPS(Uninterruptible Power Supply). A single-phase PFC converter with 1-switch voltage doubler strategy needs a diode bridge and one bidirectional active switch. Thus it is possible to reduce the material cost. However, the study results of current controller design and comparison of current control method has not been known after the converter circuit was proposed. For the performance comparison of current control, single-phase 3 kVA double-conversion UPS was tested. The performance of PI and PR current controller is experimentally confirmed with followings - input current reference tracking, input power factor correction and input current THD suppression.

마이크로 프로세서를 이용한 무인운반차량의 주행제어에 관한 연구 (A Study on the Driving Control for the Automated Guided Vehicle using Microprocessor)

  • 김병기;김진태;김윤상;오현철;이해기;안두수
    • 대한전기학회:학술대회논문집
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    • 대한전기학회 1998년도 추계학술대회 논문집 학회본부 B
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    • pp.432-434
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    • 1998
  • Recently, For the material transport is increased, the AGV(Automated Guided Vehicle) is the most important part in the industrial factory. So we treat the navigation control problem and experimental results using microprocessor. In navigation control, we have faced with velocity control problem related to guide path tracking problem. Carefully, In the straight line, the AGV moves at its high speed, but in the curve line, especially when the radian ratio is very big it is difficult to follow guide line. So, Using fuzzy controller we have simulated the guide path following AGV according to the varying velocity and experimented it with microprocessor.(Intel 80C196KC) Now, If we use the AGV industrial factory, we will improve the product and efficiency in spite of changing the factory environment.

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Gaze Differences between Expert and Novice Teachers in Science Classes

  • Kim, Won-Jung;Byeon, Jung-Ho;Lee, Il-Sun;Kwon, Yong-Ju
    • 한국과학교육학회지
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    • 제32권9호
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    • pp.1443-1451
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    • 2012
  • This study aims to investigate the gaze patterns of two expert and two novice teachers in one hour of lecture type class. Teachers recruited from the same middle school conducted the class each, wearing an eye-tracker. Gaze rate and gaze movement pattern were analyzed. The scene where teachers faced in the classroom was categorized into three zones; student zone, material zone, and non-teaching zone. Student zone was divided into nine areas of interest to see the gaze distribution within the student zone. Expert teachers showed focused gaze on student zone while novice teachers' gaze rate was significantly higher at the non-teaching zone, compared to expert teachers' one. Within student zone, expert teachers' gaze spread to the rear areas, but novice teachers' one was narrowly resided in the middle areas of the student zone. This difference in gaze caused different eye movement pattern: experts' T pattern and novices' I pattern. On the other hand, both teacher groups showed the least gaze rate onto the left and right front areas. Which change is required to teachers' gaze behavior and what must be considered in order to make effective teacher gaze in the classroom setting were discussed.

자동차 드럼 브레이크의 스퀼 전산 해석 연구 (Computational Study of Automotive Drum Brake Squeal)

  • 정택수;조종두
    • 한국자동차공학회논문집
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    • 제22권7호
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    • pp.16-22
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    • 2014
  • Automotive NVH on brake operation is mainly caused by a coupling action of vehicle speed and inter parts friction and its frequency occurs over a broad band of 0.1 kHz~10 kHz. Especially, squeal noise, being a self-excited vibration generated by friction force between drum and lining, occurs over 1 kHz and consequently dynamic instability is induced when friction energy is applied to a brake vibration system. The squeal strongly depends on nonlinear properties influenced by the material of lining, velocity of vehicle, and the dynamic properties of a brake system. The dynamic properties are considered as a main influential design factor to squeal noise, however the analysis of the properties are rarely facilitated due to arbitrariness of shape by wearing down. In this paper, we research generating tendency of squeal noise through complex eigenvalue analysis, tracking drum brake's unstable modes in accordance with the wear shape of drum and lining such as tapered and bellmouth shape, and analyze computed unstable modes by variable shapes.

RGB-D 센서 및 3D Virtual Clothing CAD활용에 의한 패션소재의 동적표현 시스템에 대한 연구 (A Study on the Dynamic Expression of Fabrics based on RGB-D Sensor and 3D Virtual Clothing CAD System)

  • 이지은;김슬기;김종준
    • 패션비즈니스
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    • 제17권1호
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    • pp.30-41
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    • 2013
  • Augmented reality techniques have been increasingly employed in the textile and fashion industry as well as computer graphics sectors. Three-dimensional virtual clothing CAD systems have also been widely used in the textile industries and academic institutes. Motion tracking techniques are grafted together in the 3D and augmented reality techniques in order to develop the virtual three-dimensional clothing and fitting systems in the fashion and textile industry sectors. In this study, three-dimensional virtual clothing sample has been prepared using a 3D virtual clothing CAD along with a 3D scanning and reconstruction system. Motion of the user has been captured through an RGB-D sensor system, and the virtual clothing fitted on the user's body is allowed to move along with the captured motion flow of the user. Acutal fabric specimens are selected for the material characterization. This study is a primary step toward building a comprehensive system for the user to experience interactively virtual clothing under real environment.

변형하는 가스 이송관 내에서 전파하는 탄화수소화염의 수치 해석 모델링 (Numerical simulation on propagation of hydrocarbon flame in a deformable tube)

  • 곽민철;여재익
    • 한국추진공학회:학술대회논문집
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    • 한국추진공학회 2012년도 제38회 춘계학술대회논문집
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    • pp.304-308
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    • 2012
  • 본 연구는 에틸렌-공기 혼합물로 채워져 있는 변형 가능한 구리 관에서의 초음속 화염 전파를 수치적으로 살펴보았다. 탄화수소의 화염 전파를 해석하기 위하여 지배방정식으로 Navier-Stokes 방정식과 Arrhenius 형태의 1단계 화학 반응식을 활용하였으며 변형 가능한 관을 해석하기 위하여 Inviscid Euler 방정식을 활용하였다. 또한, 두 물질 간 경계면 추적을 위하여 Level-set 기법을, 경계값 결정을 위하여 ghost fluid 기법을 사용하였다. 이러한 수치적 기법을 바탕으로 관의 변화에 따른 초음속 화염 내 팽창파의 전파 및 그에 따른 간섭 현상을 밀도 및 속도 변화를 통해 확인하였으며 초음속 화염 전파에도 안전성이 확보되는 최소 관 두께를 예측할 수 있는 수치적 기반을 마련하였다.

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소방공무원의 직업 적성도 도입에 관한 연구 (Study on the adoption of vocational aptitude test in the fire service)

  • 박경진;이봉우;이근출;남기훈
    • 한국산업융합학회 논문집
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    • 제22권2호
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    • pp.155-161
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    • 2019
  • Recently, increases in major disasters such as fires, earthquakes and typhoons have raised public expectations for safety. In addition to this increase in expectations of safety, the government continues to push for more manpower and better treatment for firefighters who are operating in the disaster scene. Despite the improvement of working conditions and increased welfare for firefighters, however, the incidence and turnover of various mental diseases continues to increase. It is reported that many of the diseases such as post-traumatic stress disorder and the turnover of firefighters are due to a mismatch in individual's personality and work environment. In this study, 108 firefighters were evaluated for their vocational aptitude in the new curriculum. Based on the analysis results, new firefighters were proposed to provide employment and education training improvements, and to provide job security suitable for the individual's personality type through the introduction of the vocational aptitude test for firefighters who are working in the fire service. In addition, we would like to use the vocational aptitude test as a material for reducing post-traumatic stress disorder and increasing turnover through long-term tracking and observation, rather than from a one-off perspective.