• 제목/요약/키워드: Three stage

검색결과 5,288건 처리시간 0.038초

Multiobjective Optimization of Three-Stage Spur Gear Reduction Units Using Interactive Physical Programming

  • Huang Hong Zhong;Tian Zhi Gang;Zuo Ming J.
    • Journal of Mechanical Science and Technology
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    • 제19권5호
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    • pp.1080-1086
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    • 2005
  • The preliminary design optimization of multi-stage spur gear reduction units has been a subject of considerable interest, since many high-performance power transmission applications (e.g., automotive and aerospace) require high-performance gear reduction units. There are multiple objectives in the optimal design of multi-stage spur gear reduction unit, such as minimizing the volume and maximizing the surface fatigue life. It is reasonable to formulate the design of spur gear reduction unit as a multi-objective optimization problem, and find an appropriate approach to solve it. In this paper an interactive physical programming approach is developed to place physical programming into an interactive framework in a natural way. Class functions, which are used to represent the designer's preferences on design objectives, are fixed during the interactive physical programming procedure. After a Pareto solution is generated, a preference offset is added into the class function of each objective based on whether the designer would like to improve this objective or sacrifice the objective so as to improve other objectives. The preference offsets are adjusted during the interactive physical programming procedure, and an optimal solution that satisfies the designer's preferences is supposed to be obtained by the end of the procedure. An optimization problem of three-stage spur gear reduction unit is given to illustrate the effectiveness of the proposed approach.

Modeling and Multivariable Control of a Novel Multi-Dimensional Levitated Stage with High Precision

  • Hu Tiejun;Kim Won-jong
    • International Journal of Control, Automation, and Systems
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    • 제4권1호
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    • pp.1-9
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    • 2006
  • This paper presents the modeling and multivariable feedback control of a novel high-precision multi-dimensional positioning stage. This integrated 6-degree-of-freedom. (DOF) motion stage is levitated by three aerostatic bearings and actuated by 3 three-phase synchronous permanent-magnet planar motors (SPMPMs). It can generate all 6-DOF motions with only a single moving part. With the DQ decomposition theory, this positioning stage is modeled as a multi-input multi-output (MIMO) electromechanical system with six inputs (currents) and six outputs (displacements). To achieve high-precision positioning capability, discrete-time integrator-augmented linear-quadratic-regulator (LQR) and reduced-order linearquadratic-Gaussian (LQG) control methodologies are applied. Digital multivariable controllers are designed and implemented on the positioning system, and experimental results are also presented in this paper to demonstrate the stage's dynamic performance.

정밀 위치 결정 및 고하중 부담 능력을 지닌 6-자유도 스테이지의 설계 (Design of a 6-DOF Stage for Precision Positioning and Large Force Generation)

  • 신현표
    • 한국정밀공학회지
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    • 제30권1호
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    • pp.105-112
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    • 2013
  • This paper presents the structural design and finite element analysis of precision stage based on a double triangular parallel mechanism for precision positioning and large force generation. Recently, with the acceleration of miniaturization in mobile appliances, the demand for precision aligning and bonding has been increasing. Such processes require both high precision and large force generation, which are difficult to obtain simultaneously. This study aimed at constructing a precision stage that has high precision, long stroke, and large force generation. Actuators were tactically placed and flexure hinges were carefully designed by optimization process to constitute a parallel mechanism with a double triangular configuration. The three actuators in the inner triangle function as an in-plane positioner, whereas the three actuators in the outer triangle as an out-of-plane positioner. Finite element analysis is performed to validate load carrying performances of the developed precision stage.

초정밀 스테이지 설계 및 제작

  • 강중옥;한창수;홍성욱
    • 한국반도체및디스플레이장비학회:학술대회논문집
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    • 한국반도체및디스플레이장비학회 2003년도 추계학술대회 발표 논문집
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    • pp.177-181
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    • 2003
  • This paper presents a 3-axis fine positioning stage. All the procedure concerning the design and fabrication of the stage are described. The stage considered here is composed of flexure hinges, piezoelectric actuators and their peripherals. A special flexure hinge is adopted to be able to actuate the single stage in three axes at the same time. A ball contact mechanism is introduced into the piezoelectric actuator to avoid the cross talk among the axes. The final design is obtained with the theoretical analysis on the stage. An actual fine stage is developed and the design specifications are verified through an experiment.

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한반도 후빙기의 저지대 식생사 (The Post-glacial Vegetation History of the Lowland in Korean Peninsula)

  • 최기룡
    • The Korean Journal of Ecology
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    • 제21권2호
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    • pp.169-174
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    • 1998
  • This is the review of vegetational history of the post-glacial period in Korea. most of studies for vegetational changes are located in the lowland alluvial plain, especially below the hilly zone of western and eastern coastal regions of Korea. A couple of methods, pollen analysis and radiocarbon dating, have been employed in these studies. These results lead us to establish the pollen zonation in Korea as the followings. Yasuda et al.(1980) classified six period in Yongrang lake of sokcho. These are as follow I. 17,000-15,000yr B.P.: Picea, Abies, Pinus(Haploxylon), Larix stage, II.15,000-10,000yr B.P:Herb, Pteridophyta stage, III.10.000-6,700yr BP.:Quercus stage, IV.6,700-4,500yr B.P.:Pinus, Quercus, Carpinus stage, V.4,500-1,400yr B.P.:Quercus. Pinus stage, VI.1,400yr B.P.-present: Pinus, Herbs stage. Jo(1979) also divided the period into two stages from the outcomes of analysis done in Jumoonjin and other sites I.10,000-6,000yr B.P.:Quercus stage, II.6,000-present: Pinus-Quercus stage, and three substages: IIa.6,000-3,400 yr B.P.:lower Pinus stage, IIb.3,400-2,000yr B.P.:Pinus-Quercus stage, IIc.2,000-present: Pinus stage. Choi(1993, 1996) divided the period into three stages: I.6,000-5,000yr B.P.:Alnus, Quercus stage, II.5,000-4,000yr B.P.: Alnus, Quercus, Pinus stage, III.4,500-2,600yr B.P.: Alnus, Pinus stage. In the period around 6,000yr B.P. distinct dominant species clearly occupied the lowland of the eastern and western coasts. Thus, this strongly supports the fact that even if Korea experienced its warm and wet climate after the lateglacial, it underwent a different environmental change, dry climate, compared to the regions of Japan.

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Food safety knowledge and practice by the stages of change model in school children

  • Kang, Nam-E;Kim, Ju-Hyeon;Kim, Young-Soon;Ha, Ae-Wha
    • Nutrition Research and Practice
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    • 제4권6호
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    • pp.535-540
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    • 2010
  • In this study, 342 grade 4-6 elementary school students in Gyeonggi-do were recruited to determine their readiness to change food safety behavior and to compare their food safety knowledge and practices by the stages of change. The subjects were divided into three stages of change; the percentage of stage 1 (precontemplation) was 10.1%, the percentage of stage 2 (contemplation and preparation) was 62.4%, and that of stage 3 (action and maintenance) was 27.5%. Food safety knowledge scores in stage 3 (4.55) or stage 2 (4.50) children were significantly higher than those in stage 1 children (4.17) (P < 0.05). The two food safety behavior items "hand washing practice" and "avoidance of harmful food" were significantly different among the three groups (P < 0.05). Stages of change were significantly and positively correlated with food safety knowledge and practice. Age was significantly and negatively correlated with the total food safety behavior score (r = -0.142, P < 0.05). The most influential factor on the stage of change was a mother's instruction about food safety (P < 0.01).

콘서트홀에서 무대음향에 대한 확산체의 영향 (The Effect of Stage diffusers on the Stage Acoustics in a Concert Hall)

  • 이충화;전진용
    • 한국음향학회지
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    • 제24권3호
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    • pp.171-177
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    • 2005
  • 본 논문에서는 콘서트홀에서 확산체의 Early Stage Support (ST1)에 대한 영향을 알아보기 위하여 1:25 축소모형에서 8지점을 설정하여 ST1을 측정하였다. 무대 바닥에 의한 영향을 살펴보기 위하여 흡음천의 유무에 따라 ST1의 결과값의 차이를 살펴보았다. 무대측벽에 대한 영향을 살펴보기 위하여 기존의 확산체, 확산체를 제거한 경우와 반구 확산체의 3가지 형태의 확산체를 사용하여 측벽의 변화에 의한 ST1 값의 결과를 살펴보았다. 결과적으로 무대 바닥에서의 흡음천의 사용은 ST1에서 고주파의 저감을 일으켰으나 평균값에는 큰 차이가 없었으며, 3가지 형태의 확산체는 뚜렷한 차이를 보이지 않았으나 측정 지점에 따라 ST1 값의 차이가 발생하였고, 특히 반구 확산체에서는 ST1 값이 고르게 분포하였다. 따라서 무대 바닥은 상대적으로 ST1의 변화에 큰 영향을 주지 않았고, 무대 측벽의 형상은 확산현상에 의해 ST1의 분포에 영향을 주었다.

벼 흰빛잎마름병균의 병원성 발현과 벼의 품종 및 생육시기와의 관계 (Interactions among Isolates of Xanthomonas oryzae, Rice Varieties and Growth Stages of Hosts)

  • 조용섭;이순구
    • 한국응용곤충학회지
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    • 제18권2호
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    • pp.77-84
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    • 1979
  • 벼 흰빛잎마름병균의 10균주(I군 3균주, II군 4균주, III군 3균주)를 저항성이 서로 다른 벼품종 '밀양 23호'(김남풍군), '유신'(황옥군), '통일'(Rantaiemas군)의 유묘기와 분얼초기, 최고분얼기, 지엽기에 각각 접종하였다. 그 결과 1) 병원성 발현의 양상이 균주 간 매우 다양하였다. 2) 특히 II군의 균주들은 같은 군균내에서도 변이가 매우 큰 것으로 나타났다. II군은 더 많은 균형으로 세분될 수 있었다. 3) 생육시기 별로 병원성 발현 양상이 달랐으며, 대체로 지엽기 이후 높은 발병을 나타내었다. II군중 G 7716균주는 출수이후에야 비로소 '유신'품종에 발병을 일으킬 수 있었다. 4) 통계분산분석(ANOVA) 결과, 각각 다른 균형의 균주, 품종, 생육시기가 발병정도의 분산에 주요인으로 작용하였고, 균주와 품종간의 상호작용(interaction)에 유의성이 있었으나 다른 요인간에는 없었다.

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국지풍모델을 이용한 연안지역 거대 점오염원의 이류확산 수치모의 (Numerical Simulation of Dispersion of a Vast Point Source in Coastal Area using the Local Wind Model)

  • 전병일
    • 한국환경과학회지
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    • 제7권4호
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    • pp.511-522
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    • 1998
  • The two-stage numerical model was used to study the relation between three-dimensional local wind seal area for Korean peninsula. The first stave is three dimensional time-dependent local wind model which elves the wind field and vertical diffusion coefncient. The second stage is advection/duusion model which uses the results of the first stage as input data. First, wand fields on Korean peninsula for none synoptic scale wand showed typical land and sea breeze circulation, and the emitted particles were transported by sea breeze for daytime, emissions return to sea by land breeze for nighttime.

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