• Title/Summary/Keyword: slope angle

검색결과 800건 처리시간 0.029초

만곡수로에서의 곡률반경 변화에 따른 흐름특성 (Flow Characteristics for the Variation of Radius of Curvature in Open Channel Bends)

  • 윤세의;이종태
    • 물과 미래
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    • 제23권4호
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    • pp.435-444
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    • 1990
  • 만곡수로에서의 곡률반경에 대한 하폭비 변화에 따른 흐름특성을 단순화된 수치모형을 이용하여 분석하였다. 각 운동량 방정식과 힘의 평형원리로부터 각가 2차 흐름속도와 횡방향하상경사를 계산하였다. 깊이 방향으로 적분된 연속방정식과 흐름방향의 운동방정식을 양적 유한차분법으로부터 그 해를 구하였다. 곡률반경에 대한 하폭의 비를(Rc/B) 2.7, 5.4 및 8.1로 변화시키면 수치실험을 실행하여, 그 결과로부터 2차 흐름속도, 흐름방향유속, 최대유속의 이동경로, 편의각 및 질량이동유속에 관한 특성을 분석하였다.

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Treadmill에서의 경사로 정상보행에 관한 동작분석 (Motion Analysis of Tresidmill Walking with Various Slopes at a Normal Speed)

  • 김영호;양길태;문무성
    • 대한의용생체공학회:의공학회지
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    • 제18권1호
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    • pp.71-78
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    • 1997
  • Kinematic and kinetic studies were performed to investigate the walking characteristics on a treadmill with various slopes at the same speed of 1.25m/sec. Six different slopes of the treadmill were selected . -4%(-$2.3^{\circ}$), 0%($0^{\circ}$), 5%($2.9^{\circ}$), 10%($5.7^{\circ}$), 15%($8.6^{\circ}$), and 20%($11.3^{\circ}$). With increased slopes of the treadmill, both hip and knee flexion angles significantly increased at initial contact, and the maximum hip flexion during swing phase and the maximum knee flexion during stance phase also significantly increased Ankle dorsiflexion angle at initial contact and the maximum dorsiflexion increased with increased slopes. However, the maximum plantarflexion in early swing was slightly reduced with increased slopes. Hip extension in late stance and the maximum knee flexion in early swing was not changed sigilificantly with increased slopes. As for the vertical ground reaction force, compared to the yond level walking, both the first and the second peak forces increased, but the mid-support force decreased.

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RETScreen 모델이용 태양열온수시스템 초기설계단계 설계용량 최적화기법의 TRNSYS 모델과의 비교분석 (Comparative Study on Size Optimization of a Solar Water Heating System in the Early Design Phase Using a RETScreen Model with TRNSYS Model Optimization)

  • 이경호
    • 설비공학논문집
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    • 제25권12호
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    • pp.693-699
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    • 2013
  • This paper describes a method for size optimization of the major design variables for solar water heating systems at the stage of concept design. The widely used RETScreen simulation tool was used for optimization. Currently, the RETScreen tool itself does not provide a function for optimization of the design parameters. In this study, an optimizer was combined with the software. A comparative study was performed to evaluate the RETScreen-based approach with the case study of a solar heating system in an office building. The optimized results using the RETScreen model were compared to previously published results with the TRNSYS model. The objective function of the optimization is the life-cycle cost of the system. The optimized design results from the RETScreen model showed good agreement with the optimized TRNSYS results for the solar collector area and storage volume, but presented a slight difference for the collector slope angle in terms of the converged direction of the solutions. The energy cost, life-cycle cost, and thermal performance regarding collector efficiency, system efficiency, and solar fraction were compared as well, and the RETScreen model showed good agreement with the TRNSYS model for the conditions of the base case and optimized design.

도시철도의 직류전력 공급을 위한 사이리스터를 사용한 병렬 듀얼 컨버터의 순차적 모드 전환 제어 알고리즘에 대한 연구 (A Studies for Sequential Mode Change Control Algorithm of the Parallel Dual Converter of Using Thyristor for Supplying the Urban Railway DC Power)

  • 한성우;김성안;조윤현;변기식
    • 전기학회논문지
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    • 제65권3호
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    • pp.511-519
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    • 2016
  • This paper is proposed control algorithm for the using thyristor of the parallel dual converter for Urban railway power supply in order to return the regenerative power generated by regenerative braking in urban railway train. Conventional control algorithm of Thyristor dual converter for urban railway power supply has voltage variation within a control range of hysteresis band. The purposed control algorithm of the parallel thyristor dual converter is to maintain a constant voltage without voltage variation in accordance with variable load through the Sequential mode change. And the control algorithm need calculating optimum initial firing angle to consider magnitude of the load current slope. For this purpose, Proposed algorithm for sequential conversion mode of the dual converter was verified by applying for the simulation.

AlTiN코팅공구를 사용한 플라스틱금형강의 기계가공성 평가 (Machinability Evaluation of the Plastic Mould Steel using AlTiN Coated Tool)

  • 이승철;조규재
    • 한국생산제조학회지
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    • 제18권6호
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    • pp.629-635
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    • 2009
  • In this research, KP-4, one of the plastic mold steels, was coated with the AlTiN from one layer to four layers by the PVD method in the $\Phi$ 8mm cemented carbide ball end mill. Coated KP-4 was processed with various conditions. For example, slope of $15^{\circ}$, $30^{\circ}$ and $45^{\circ}$ the spindle rotation speed was changed from 10,000rpm to 16,000rpm, the tool feeding speed was changed from 1,300mm/min to 1,700mm/min, the depth of cut was also changed from 0.3mm to 0.9mm, and etc. Cutting component force according to the coating layer number, and surface roughness were studied. The cutting component force showed a good agreement better the up ward direction than the down ward direction under all experimental conditions. In case of the condition per the material shape, it was lessen when the tool have larger angle because the average effective diameter of the tool is larger. The surface roughness showed good condition in case of the up ward than the down ward direction. And, in the 3rd layer of AlTiN coating, it showed the most suitable condition.

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Unambiguous 3D Surface Measurement Method for a Micro-Fresnel Lens-Shaped Lenticular Lens Based on a Transmissive Interferometer

  • Yoon, Do-Young;Kim, Tai-Wook;Kim, Minsu;Pahk, Heui-Jae
    • Journal of the Optical Society of Korea
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    • 제18권1호
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    • pp.37-44
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    • 2014
  • The use of a laser interferometer as a metrological tool in micro-optics measurement is demonstrated. A transmissive interferometer is effective in measuring an optical specimen having a high angle slope. A configuration that consists of an optical resolution of 0.62 micron is adapted to measure a specimen, which is a micro-Fresnel lens-shaped lenticular lens. The measurement result shows a good repeatability at each fraction of facets, however, a reconstruction of the lens shape profile is disturbed by a known problem of $2{\pi}$-ambiguity. To solve this $2{\pi}$-ambiguity problem, we propose a two-step phase unwrapping method. In the first step, an unwrapped phase map is obtained by using a conventional unwrapping method. Then, a proposed unwrapping method based on the shape modeling is applied to correct the wrongly unwrapped phase. A measured height of each facet is compared with a profile result measured by AFM.

VLM-ST용 CAD/CAM 시스템에서 단위 형상층 생성 방법 및 적용예 (Generation of Unit Shape Layer on CAD/CAM System for VLM-ST)

  • 이상호;안동규;최홍석;양동열;문영복;채희창
    • 한국CDE학회논문집
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    • 제7권3호
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    • pp.148-156
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    • 2002
  • Most Rapid Prototyping (RP) processes adopt a solid Computer Aided Design (CAD) model, which will be sliced into thin layers of constant thickness in the building direction. Each cross-sectional layer is successively deposited and, simultaneously, bonded onto the previous layer; and eventually the stacked layers from a physical part of the model. A new RP process, the transfer-type Variable Lamination Manufacturing process using expandable polystyrene foam sheet (VLM-ST), has been developed to reduce building time and to improve the surface finish of parts with the thick layers and a sloping surface. This paper describes the generation of Unit Shape Layer (USL), the cutting path data of the linen. hotwire cutter for the VLM-ST process. USL is a three-dimensional layer with a thickness of more than 1 mm and a side slope, and it is the basic unit of cutting and building in the VLM-ST process. USL includes data such as layer thickness, positional coordinates, side angles of each layer, hotwire cutting speed, the heat input to the hotwire, and reference shape. The procedure of generating USL is as follows: (1)Generation of the mid-slice from the CAD model, (2)Conversion of the mid-slice into a simply connected domain, (3)Generation to the reference shape for the mid-slice, (4)Calculation of the rotation angle of the hotwire of the cutting system.

Ramifications of Structural Deformations on Collapse Loads of Critically Cracked Pipe Bends Under In-Plane Bending and Internal Pressure

  • Sasidharan, Sumesh;Arunachalam, Veerappan;Subramaniam, Shanmugam
    • Nuclear Engineering and Technology
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    • 제49권1호
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    • pp.254-266
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    • 2017
  • Finite-element analysis based on elastic-perfectly plastic material was conducted to examine the influence of structural deformations on collapse loads of circumferential through-wall critically cracked $90^{\circ}$ pipe bends undergoing in-plane closing bending and internal pressure. The critical crack is defined for a through-wall circumferential crack at the extrados with a subtended angle below which there is no weakening effect on collapse moment of elbows subjected to in-plane closing bending. Elliptical and semioval cross sections were postulated at the bend regions and compared. Twice-elastic-slope method was utilized to obtain the collapse loads. Structural deformations, namely, ovality and thinning, were each varied from 0% to 20% in steps of 5% and the normalized internal pressure was varied from 0.2 to 0.6. Results indicate that elliptic cross sections were suitable for pipe ratios 5 and 10, whereas for pipe ratio 20, semioval cross sections gave satisfactory solutions. The effect of ovality on collapse loads is significant, although it cancelled out at a certain value of applied internal pressure. Thinning had a negligible effect on collapse loads of bends with crack geometries considered.

생리학적인 하중 조건에서 소 상완골 연골의 기계적 특성 (In Situ Mechanical Response of Bovine Humeral Head Articular Cartilage in a Physiological Loading Environment)

  • 박성훈
    • 한국정밀공학회지
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    • 제25권1호
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    • pp.145-150
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    • 2008
  • One of the unresolved questions in articular cartilage biomechanics is the magnitude of the dynamic modulus and tissue compressive strains under physiological loading conditions. The objective of this study was to characterize the dynamic modulus and compressive strain magnitudes of bovine articular cartilage at physiological compressive stress level and loading frequency. Four bovine calf shoulder joints (ages 2-4 months) were loaded in Instron testing system under load control, with a load amplitude up to 800 N and loading frequency of 1 Hz, resulting in peak engineering stress amplitude of ${\sim}5.8\;MPa$. The corresponding peak deformation of the articular layer reached ${\sim}27%$ of its thickness. The effective dynamic modulus determined from the slope of stress versus strain curve was ${\sim}23\;MPa$, and the phase angle difference between the applied stress and measured strain which is equivalent to the area of the hystresis loop in the stress-strain response was ${\sim}8.3^{\circ}$. These results are representative of the functional properties of articular cartilage in a physiological loading environment. This study provides novel experimental findings on the physiological strain magnitudes and dynamic modulus achieved in intact articular layers under cyclical loading conditions.

X-ray 영상을 이용한 척추측만증 정도 검출 알고리즘 개발 (Development of Level Detecting Algorithm for Scoliosis using X-ray Image)

  • 박은정;정주영;이기영;이상식
    • 한국정보전자통신기술학회논문지
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    • 제4권4호
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    • pp.242-249
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    • 2011
  • 본 연구에서는 척추측만증의 정도를 자동으로 검출할 수 있는 알고리즘을 개발하였다. 개발한 시스템은 X-ray 영상 원본을 사용하였다. 척추 만곡 정도에 대한 수식은 S<0 이고, L>0 인 성립 조건을 갖는 $Y=SX^2+L$의 함수식이다. X축의 길이는 변경이 가능하고 모든 척추선 함수 그래프에서 동일하게 적용되었으며, 기울기 $S=-L/92^2$이다. 척추측만증 정도에 대한 미분 그래프의 수식은 Y'=2SX임을 알 수 있었고, 추출된 척추선에 대한 분류와 척추측만증 정도에 대한 분류가 가능한 알고리즘으로 판단된다.