• Title/Summary/Keyword: axis angle

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Voltage Angle Control of Surface Permanent Magnet Synchronous Motor for Low-Cost Applications

  • Lee, Kwang-Woon;Kim, Guechol
    • 전기전자학회논문지
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    • 제22권3호
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    • pp.716-722
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    • 2018
  • This paper presents a voltage angle control strategy for surface permanent magnet synchronous motor (SPMSM) drives used in low-cost applications, wherein a current vector control is not employed. In the proposed method, the current vector control scheme, which requires high precision phase-current sensing units and a fast calculation capability of a motor drive controller, is replaced with the voltage angle controller. The proposed voltage angle controller calculates a d-axis voltage command to make the d-axis current zero by using a simple equation obtained from the voltage equation of SPMSM. The proposed method shows performance similar to the current vector controlled SPMSM drive during steady-states and its structure is very simple and thus it can be easily implemented with a low-cost microcontroller. The effectiveness of the proposed method is verified through simulations and experiments.

Ellipsometric Characterization of Rubbed Polyimide Alignment Layer in Relation with Distribution of Liquid Crystal Molecules in Twisted Nematic Cell

  • Cho, Sung Yong;Park, Sang Uk;Yang, Sung Mo;Kim, Sang Youl
    • Current Optics and Photonics
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    • 제2권2호
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    • pp.185-194
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    • 2018
  • Ultra-small optical anisotropy of a rubbed polyimide (PI) alignment layer is quantitatively characterized using the improved reflection ellipsometer. Twisted nematic (TN) cells are fabricated using the rubbed PIs of known surface anisotropy as alignment layers. Distribution of liquid crystal (LC) molecules in the TN cell is characterized using transmission ellipsometry. The retardation of the rubbed PI surface increases as rubbing strength increases. The tilt angle of the optic axis of the rubbed PI surface decreases as rubbing strength especially as the angular speed of the rubbing roller increases. Pretilt angle of LC molecules in the TN cell shows strong correlation with tilt angle of the optic axis of the rubbed PI surface. Both the apparent order parameter and the effective twist angle of the LC molecules in the TN cell decrease as the pretilt angle of LC molecules increases.

소형견종의 후지정렬 측정 (Determination of Pelvic Limb Alignment in Small-breed Dogs)

  • 김주호;허수영;나지영;김남수;이기창;정성목;이해범
    • 한국임상수의학회지
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    • 제32권6호
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    • pp.481-485
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    • 2015
  • 후지 전체의 정렬 평가에 필요한 정렬각도의 정상치를 측정하기 위하여, 정형외과적 질환이 없고 육안 또는 방사선 검사에서 각기형이 없는 것으로 판단되는 소형견 사체(말티즈, 푸들, 시추, 요크셔테리어) 의 후지 60개를 사용하였다. 각각의 후지를 완전히 신장시켜 전면 방사선 사진을 촬영하였으며, 이를 통해 기계적경골대퇴골각도(mechanical tibiofemoral angle, mTFA), 기계적중족경골각도 (mechanical metatarsotibial angle (mMTTA) 기계축-대퇴각도(mechanical axis-femur angle (MAFA), 기계축-중족각도(mechanical axis-metatarsus angle (MAMTA)을 측정하였으며, 무릎관절과 뒷발목관절의 기계축변위(mechanical axis deviation, SMAD or TMAD)의 평균값과 95% 신뢰구간 값을 전체 그리고 품종별로 측정하였다. 소형견 전체의 mTFA, MTTA, MAFA, MAMTA의 95% 신뢰구간 값은 각각 $5.7-7.4^{\circ}$, $-2.2--0.8^{\circ}$, $3.5-4.5^{\circ}$, $1.0-2.0^{\circ}$였으며, SMAD와 TMAD는 2.1-2.7%, 0.5-1.0%로 측정되었다. 본 연구에서 제시한 소형견의 후지정렬 측정법과 정상치는 소형견종의 후지 각기형의 진단 및 평가, 수술 계획에 있어 유용하게 사용될 수 있을 것이라 사료된다.

근위경골절골술에서 해부학적 축과 역학적 축의 변화가 경골후방경사각에 미치는 영향 (The Effect of Anatomical Axis and Mechanical Axis on Change of Posterior Tibial Slope Angle in PTO(Proximal Tibial Osteotomy))

  • 신은지;김철웅;이호상;배지훈;왕준호;;오동준
    • 대한기계학회:학술대회논문집
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    • 대한기계학회 2008년도 추계학술대회A
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    • pp.1543-1546
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    • 2008
  • The purpose of this study was to investigate factors affecting the change of tibial posterior slope and introduce a mathematical model which calculate, through 3-dimensional analysis of the proximal tibia, how the angle of the opening wedge along the anteromedial tibial cortex influences the tibial posterior slope and valgus correction when performing a medial open wedge osteotomy. This mathematical model with navigation system can be guidelines which provide surgeons on preoperative and intraoperative measurements to maintain or correct the tibial slope and to obtain the desired valgus correction of the lower limb during an opening wedge osteotomy.

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6축 병렬기구 공작기계의 머신 시뮬레이션과 앵글밀링헤드 적용에 관한 연구 (A Study on the Application of Machine Simulation and Angle Milling Head of a 6-Axis Parallel Kinematic Machine)

  • 이인수;김해지;김남경
    • 한국기계가공학회지
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    • 제16권5호
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    • pp.47-54
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    • 2017
  • This study examines the implementation of a kinematic machining tool to evaluate the interference and collision phenomenon of 5-axis machining of wing ribs from airplanes, particularly for a large-size model airplane. We develop a machine simulation model of a parallel kinematic machining tool that can operate in a virtual space, which is equivalent to the authentic conditions in the field. The investigation of the simulation function elements indicates the necessity to generate the 6-axis machining, which attaches an angle head to the main axis of the machine. Using an NC program for the wing ribs, we attempt to verify the correspondence and conformity between the machine simulation model and the actual equipment.

유압 사축식 액셜 피스톤 펌프의 로드 구동에 관한 연구 제1보: 구동 메카니즘의 이론해석 (A Study on the Driving of Rods in Hydraulic Bent-axis-type Axial Piston Pump Part 1: The Theoretical Analysis of Driving Mechanism)

  • 김종기;오석형;정재연
    • Tribology and Lubricants
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    • 제14권4호
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    • pp.51-57
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    • 1998
  • Recently, bent-axis-type axial piston pumps driven by rods being in extensively used in the world, because of simple design, lightweight, effective cost. So, to guarantee the quality of bent-axis-type axial piston pumps driven by rods, it is necessary to know characteristics of the driving mechanism of rods. But, as they perform both reciprocating and spinning motions, it is difficult to understand driving mechanism. In this paper, I studied the theoretical driving mechanisms of cylinder block driven by rods through geometric method. I found that the cylinder block was driven by one rod in limited area and the driving area was changed by rod's tilting angle and cylinder block's swivel angle.

승마 평보 시 숙련자의 등자길이 피팅에 따른 기승자세정열의 운동학적 비교분석 (Kinematic Analysis of The Rider Postural Alignments According to The Fitting of Stirrups Lengths during Horse Walk of High Level Rider)

  • 류재청;현승현
    • 한국운동역학회지
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    • 제24권4호
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    • pp.329-338
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    • 2014
  • The purpose of this study was to analyze of the rider postural alignments according to the fitting of stirrups lengths during walk of high level riders. Participants selected as subject were consisted of horse riders of high level (age: $47.66{\pm}3.51yrs$, height: $168.40{\pm}4.84cm$, body weight: $73.36{\pm}15.58kg$, low extremity length: $94.76{\pm}3.98cm$, career: $23.33{\pm}5.77yrs$) and walk with 3 types of stirrup lengths(ratio of low extremity 68.04%, 73.25%, 78.48%). The variables analyzed were consisted of the displacement of Y axis (center of mass, head, thigh, shank and foot), FR angle, LR angle, dynamic postural stability index (DPSI), coefficient of variation (CV%), and distance (X axis) of low extremity limb between right and left. The displacement of Y axis in COM, thigh, shank, foot limbs were not statistically significant, but movements of head showed greater distance of B type and C type than that of A type during 1 stride of walk. The FR and LR angle in trunk of horse rider, dynamic postural stability index and, coefficient of variation didn't show significant difference statistically according to the fitting of stirrup lengths. Also the distance (X axis) of low extremity in thigh and shank didn't show significant difference statistically in between right and left, but right and left foot showed greater distance in C type than that of B and A types during walk in horse back riding. The hip and ankle joint angle not statistically significant according to stirrups lengths, But knee joint angle showed more extended according to the increase of stirrups lengths during stance and swing phase in walk.

RDC/TMD Axis I 진단에 따른 측두하악장애 환자의 측두 두부방사선적 특징에 관한 연구 (Cephalometric Characteristics of TMD Patients based on RDC/TMD Axis I Diagnosis)

  • 안지연;김용우;김영구;이정윤
    • Journal of Oral Medicine and Pain
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    • 제36권1호
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    • pp.39-51
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    • 2011
  • 본 연구는 측두하악장애의 연구 진단 기준(Research Diagnostic Criteria for Temporomandibular Disorder; RDC/TMD)을 이용하여 구분된 측두하악장애(Temporomandibular Disorder; TMD) 환자를 대상으로 안면의 골격적 양상과 TMD 사이의 연관성을 규명하고 교정 환자의 진단과 치료에 있어 RDC/TMD의 활용 가능성을 제시하고자 하였다. 서울대학교 치과병원 구강내과에 측두하악장애의 진단과 치료를 위해 내원한 여성 환자들의 의무 기록 및 방사선사진을 검토하였으며 환자의 연령이 18세 미만이거나 전신 질환, 골격적 기형 또는 측두하악관절 부위의 외상 병력이 있는 경우는 제외되었다. 총 96명의 여성 환자로부터 얻은 RDC/TMD Axis I 을 포함한 임상 검사 결과와 측방 두부규격방사선사진 (lateral cephalogram), 파노라마 방사선사진(panoramic radiograph) 및 횡두개 방사선사진(transcranial radiograph)을 이용한 방사선적 검사 결과를 분석하였다. RDC/TMD를 이용하여 집단을 분류한 후 측방 두부규격방사선사진의 각도 및 길이 요소들을 계측하여 안면의 골격 관계, 상하악 관계 및 치열 관계를 분석하였다. 통계적 분석법으로는 독립표본 t-검정(independent t-test), 일원분산분석(one-way Analysis of Variance; one-way ANOVA) 및 카이제곱 검정(chi-square test)을 이용하였고 다음과 같은 결과를 얻었다. 1. 근육 문제를 진단하는 RDC/TMD Axis I 의 제 1 군 측두 두부방사선적 특징에서 통계적 유의성이 인정되지 않았다. 2. 관절원판 변위를 임상적으로 진단하는 제 2 군에서는 개구 장애를 동반하지 않는 비정복성 관절원판 변위가 있는 경우 관절원판 변위가 없는 정상 집단에 비하여 articular angle이 큰 것으로 나타났다. 3. 관절통, 관절염 및 관절증을 진단하는 제 3 군에서는 articular angle, FMA, Bjork sum, posterior facial height 및 facial height ratio에서 유의한 차이가 있는 것으로 분석되었다. 4. TMD 진단군과 골격적 양상 사이의 관계를 단순화하기 위하여 RDC/TMD Axis I 각 군을 양분법적으로 분류한 뒤 동일 한 방식으로 분석을 시행하였다. 그 결과 제 1 군에서는 overjet, 제 2 군에서는 articular angle, facial height ratio 및 IMPA, 마지막으로 제 3 군에서는 articular angle, gonial angle, facial convexity, FMA, Bjork sum, posterior facial height, facial height ratio 및 ANB angle에서 유의한 차이를 보였다. 이상의 RDC/TMD Axis I 을 이용하여 진단된 측두하악장애 환자를 대상으로 안면의 골격적 양상과 TMD 사이의 연관성 을 분석한 결과로부터 RDC/TMD Axis I 임상 진단에 따라 진단한 측두하악장애 환자 중 제 2 군과 제 3 군의 환자들에서 측두하악장애와 관련된 것으로 알려진 하악골의 후하방 회전으로 인한 골격적 차이가 존재함을 확인하였다. RDC/TMD Axis I은 교정 전 혹은 교정 치료 진행 중에 임상 검사 및 일반 방사선사진으로부터의 제한된 정보를 바탕으로 교정 치료 중 고려하여야 할 TMD 환자를 감별하는데 유용한 정보를 제공할 수 있을 것이다.

공작물 받침대를 이용한 무심관통이송 공작물의 테이퍼링 오차 개선 (Improvement of the Tapering Error in the Centerless Through-feed Ground Parts Using a Work-rest Blade)

  • 김강
    • 한국정밀공학회지
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    • 제20권7호
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    • pp.70-77
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    • 2003
  • The centerless through-feed grinding is performed by passing the workpiece between the grinding wheel and the regulating wheel. So, the amount of removed material around the leading end, of the workpiece is always more than that around the trailing end until the leading end leaves the grinding wheel. Because of this, there are differences in diameters along the workpiece axis during grinding, and workpiece axis is not parallel to the grinding wheel axis and the contact lines between the workpiece and wheels. Thus the ground workpiece shows tapering error inherently. To eliminate this error, the workpiece axis must be kept to be parallel to the grinding wheel axis. And, the direction of the workpiece axis can be controlled by the work-rest blade. Therefore, the effects of work-rest blade inclination angle on the through-feed centerless ground part are investigated in this study. As a result, it is found that there is a positive inclination angle of the work-rest blade for minimizing the tapering error of a ground workpiece.

Mechanical performance of a new I-section weak-axis column bending connection

  • Lu, Linfeng;Xu, Yinglu;Lim, James B.P.
    • Steel and Composite Structures
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    • 제26권1호
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    • pp.31-44
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    • 2018
  • This paper reports a novel steel beam-to-column connection suitable for use in the weak axis of I-section column. Monotonic and cyclic loading experimental investigations and numerical analysis of the proposed weak-axis connection were conducted, and the calculation procedure of the beam-column relative rotation angle and plastic rotation angle was developed and described in details. A comparative analysis of mechanical property and steel consumption were employed for the proposed I-section column weak-axis connection and box-section column bending connection. The result showed that no signs of fracturing were observed and the plastic hinge formed reliably in the beam section away from the skin plate under the beam end monotonic loading, and the plastic hinge formed much closer to the skin plate under the beam end cyclic loading. The fracture of welds between diaphragm and skin plate would cause an unstable hysteretic response under the column top horizontal cyclic loading. The proposed weak-axis connection system could not only simplify the design calculation progress when I-section column is adopted in frame structural design but also effectively satisfy the requirements of 'strong joint and weak member', as well as lower steel consumption.