• Title/Summary/Keyword: tangential

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A Study on Golf Ball Spin Mechanism at Impact (골프 공의 충돌 시 스핀 생성 원리 연구)

  • Roh, Woo-Jin;Lee, Chong-Won
    • Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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    • 2007.05a
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    • pp.1017-1022
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    • 2007
  • It is important to improve the initial launch conditions of golf ball at impact between golf club and ball to get a long flight distance. The flight distance is greatly influenced by the initial launch conditions such as ball speed, launch angle and back spin rate. It is also important to analyze the mechanism of ball spin to improve the initial conditions of golf ball. Back spin rate is created by the contact time and force. Previous studies showed that the contact force is determined as the resultant force of the reaction forces normal and tangential to the club face at the contact point. The normal force causes the compression and restitution of ball, and the tangential force creates the spin. Especially, the tangential force is known to take either positive or negative values as the ball rolls and slides along the club face during impact. Although the positive and negative tangential forces are known to create and reduce the back spin rate, respectively, the mechanism of ball spin creation has not yet been discussed in detail in the literature. In this paper, the influence of the contact force between golf club and ball is investigated to analyze the mechanism of impact. For this purpose, the contact force and time at impact between golf club head and ball are computed using FEM and compared with previous results. In addition, we investigate the impact phenomenon between golf club head and ball by FEM and clarify the mechanism of ball spin creation accurately, particularly focusing on the effect of negative tangential force on ball spin rate.

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On-line Estimation of Radial Immersion Ratio Using Cutting Force and Instantaneous Cutting Force Ratio in Face Milling (정면밀링 가공 중 절삭력과 순간 절삭력 성분비를 이용한 반경방향 절입비의 실시간 추정)

  • Kim, Myeong-Gon;Gwon, Won-Tae
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.8 s.179
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    • pp.2123-2130
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    • 2000
  • Radial immersion ratio is an important factor to determine the threshold in face milling and should be estimated in process for automatic force regulation. In this paper, presented is a method of on-line estimation of the radial immersion ratio using cutting force. When a tooth finishes sweeping, sudden drop of cutting forces occurs. This force drop is equal to the cutting force that acts on a single tooth at the swept angle of cut and can be obtained from cutting force signal in feed and cross-feed direction. The ratio of cutting forces in feed and cross-feed directions acting on the single tooth at the swept angle of cut is a function of the swept angle of cut and the ratio of radial to tangential cutting force. In the research, it is found that the ratio of radial to tangential cutting force is not affected by cutting conditions and axial rake angle. Therefore, the ratio of radial to tangential cutting force determined by just one preliminary experiment can be used regardless of the cutting conditions. Using the measured cutting force and predetermined ratio, the radial immersion ratio is estimated. Various experiments show that the radial immersion ratio and instantaneous ratio of the radial to tangential direction cutting force can be estimated very well by the proposed method.

Correction Method on Mismatched Posterior Edge of Medial and Lateral Tangential Fields for Three Fields Techniques in Breast Cancer (유방암 환자의 삼문 조사 시 내외측 접면 조사야의 Posterior Edge의 어긋남의 교정)

  • Kim Hun-Jung;Loh John JK;Kim Woo-Cheol;Park Sung-Young
    • Radiation Oncology Journal
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    • v.21 no.2
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    • pp.174-181
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    • 2003
  • Purpose: The target volume for the three field technique in breast cancer include the breast tangential and supraclavicular areas. The techniques rotating the gantry and couch angles, to match these two areas, will geometrically produce mismatching of the posterior edge between the medial and lateral tangential beams. This mismatch was confirmed by film dosimetry and three-dimensional computer planning. The correction methods of this mismatching were studied in this article. Materials and Methods: After the supraclavicular field was simulated using a half beam block and the medial and lateral tangential fields, by the rotation of the couch and gantry, we compared the following two methods to correct the mismatch. The first method was the rotation of coillmator until a line drawn on the posterior edge of tangential beams before the rotation of couch aligned the line drawn on the posterior edge after the rotation. The second method was the rotation of collimator according to the formula developed by the author as follows; Co=$2sin^{-1}${$sin\{theta}\{cdot}sin(C/2)$} (Co: collimator angle, $\theta$: angle between tangential beam and table, C: couch angle) Results: The film dosimetry showed the mismatching of posterior edges of the medial and lateral tangential fields prior to the rotation of collimator, while the posterior edges matched well after the rotation of collimator according to the formula. The three-dimensional computer plan also showed that the posterior edges matched well after the rotation of collimator accordingly. The DVH of the ipsilateral lung with the proper rotation of collimator angle was better than that without the rotation of collimator angle. Conclusion: The mismatching of the posterior edges of the medial and lateral tangential fields can be recognized on the three fileld technique in breast irradiation when the gantry and couch are simultaneously rotated and can be corrected with the proper rotation of the collimator angle. The radiation dose to the ipsilateral lung could be lowered with this technique.

A Study on Radial Velocity Transformation and Uncertainty Propagation (시선속도 변환과 불확도 전파에 관한 연구)

  • Ryu, Chung-Ho;Hwang, Gyu-Hwan;Jang, Yong-Sik;Kim, Moon-Ki;Choi, Ik-Hwan
    • Journal of the Korea Institute of Military Science and Technology
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    • v.16 no.2
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    • pp.199-206
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    • 2013
  • In general, radial velocity of a target can be obtained by acquiring doppler frequency shift in case of a doppler radar, or can be obtained by acquiring range rate in case of a pulse radar. Then radial velocity can be converted to tangential velocity using aspect angle or position variation per unit time. These two ways have the same meaning in physically, but result in different uncertainty finally. In this paper, it is described not only the two transformation procedures to calculate tangential velocity from radar measurement data, but also the result of combined uncertainty comparison between these two procedures.

Thickness Measurement of Pipe Using Tangential Radiography (Tangential Radiography를 이용한 배관의 두께 평가법)

  • Lee, S.S.;Kim, Young-H.
    • Journal of the Korean Society for Nondestructive Testing
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    • v.18 no.3
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    • pp.205-210
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    • 1998
  • 이미 오래전부터 국내외에서 석유화학공장 등의 보온 배관에서 보온재를 벗기지 않고 배관의 부식 손상 및 잔존두께를 평가하는데 방사선투과시험법을 적용해 오고 있다. 그러나 배관 용접부의 결함 탐상에 관한 방사선투과법에 대한 국제 및 국내 코드는 이미 마련되어 있지만 배관의 두께와 내부에 존재하는 부착물(deposit) 등의 두께를 측정하는 것에 관련한 국제 및 국내 코드는 미비되어 시험 절차 및 시험 결과에 대한 시비가 근본적으로 존재할 수 밖에 없을 뿐만 아니라 표준화된 시험 기술의 미비로 현장에서 많은 시행착오를 동반하였다. 그러나 최근 이 시험법에 대한 관련 원안(protocol)을 확정하기 위해 각국에서 개별적으로 수행되었던 기존의 연구 결과들이 취합되고 있으며 부족한 부분들에 대한 연구가 국제 공동 연구 형식으로 이뤄지고 있다. 따라서 본 연구에서는 tangential radiography를 적용하여 보온된 배관의 잔존 두께를 평가할 수 있는 시험 방법을 제시하고자 하였다.

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Prediction of Initiation Location and Direction of Fretting Fatigue Crack (프레팅 피로 균열의 발생 위치 및 방향 예측)

  • Huh, Yong-Hak;R. E. Edwards;M.W. Brown;E.R. de Ios Rios
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.27 no.7
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    • pp.1185-1192
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    • 2003
  • Governing parameters for determination of the location of crack initiation and direction of crack initiation were investigated by performing fretting fatigue tests and analysis on Al 2024-T351. Fatigue tests were carried out using biaxial fatigue machine. It was shown that the dominant fatigue crack tended to initiate at the outer edge of one of the four bridge pads, growing at an angle beneath a pad, before turning perpendicular to the orientation of the axial load. Distribution of stresses generated during fretting fatigue loading along the interface was calculated by elastic FE simulation. It can be known that the location of crack initiation can be predicted by using the maximum tangential stress range. Futhermore, the crack initiation direction can also be predicted by a maximum tangential stress range.

A Study on the Filtration Characteristics of Baghouse with Tangential Inlet Depending on the Shape of Inner Tube (접선유입 방식 여과집진기의 내통형상 변화에 따른 집진특성 연구)

  • Choi, H.K.;Park, S.J.;Lim, J.H.;Kim, S.D.;Park, H.S.;Park, Y.O.
    • Proceedings of the KSME Conference
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    • 2001.06e
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    • pp.158-161
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    • 2001
  • A new type baghouse with tangential inlet and inner tube was developed and it's performances were evaluated. Experiments with variable shapes of inner tube were performed to suggest an optimum shape of inner tube which might decrease the dust loading onto bag filter surface and the amount of reentrained particles by internal gas flow. The dust loading was lower when inner tubes parallel to outer casing exist. When an inner tube covering around the lower portion of bag filters was used, the dust particles detached from the filter surface by cleaning process were reentraind by internal recirculating gas flow.

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The Stress Field in the Body by Tangential Loading of a Rectangular Patch on a Semi-Infinite Solid (반 무한체 위의 사각조각 표면에 작용하는 접선하중에 의한 반 무한체내의 응력 해석)

  • Lee, Mun-Ju;Gu, Yeong-Pil;Jo, Yong-Ju
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.24 no.4 s.175
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    • pp.1032-1038
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    • 2000
  • The stress field in the body by tangential loading of a rectangular patch on a semi-infinite solid has been solved analytically using potential function. The validity of result of this study was proved by Saint-Venant's principle in the remote region and in the vicinity of the surface with superposition of point loads.

ESTIMATES FOR SECOND NON-TANGENTIAL DERIVATIVES AT THE BOUNDARY

  • Gok, Burcu;Ornek, Bulent Nafi
    • Communications of the Korean Mathematical Society
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    • v.32 no.3
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    • pp.689-707
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    • 2017
  • In this paper, a boundary version of Schwarz lemma is investigated. We take into consideration a function f(z) holomorphic in the unit disc and f(0) = 0, f'(0) = 1 such that ${\Re}f^{\prime}(z)$ > ${\frac{1-{\alpha}}{2}}$, -1 < ${\alpha}$ < 1, we estimate a modulus of the second non-tangential derivative of f(z) function at the boundary point $z_0$ with ${\Re}f^{\prime}(z_0)={\frac{1-{\alpha}}{2}}$, by taking into account their first nonzero two Maclaurin coefficients. Also, we shall give an estimate below ${\mid}f^{{\prime}{\prime}}(z_0){\mid}$ according to the first nonzero Taylor coefficient of about two zeros, namely z = 0 and $z_1{\neq}0$. The sharpness of these inequalities is also proved.

Damage Assessment of Buried Pipelines due to Deep Excavation-Induced Ground Movements (지반 굴착 시 지반 거동에 따른 매설관 손상 평가)

  • Yoo, Chung-Sik;Choi, Byoung-Seok
    • Proceedings of the Korean Geotechical Society Conference
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    • 2004.03b
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    • pp.765-774
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    • 2004
  • This paper presents a damage assesment method for buried pipelines subjected to Deep Excavation-induced ground movements. Ground deformation characteristics resulting from 3D finite element analysis was represented mathematically by a hyperbolic tangential function. A parametric study was performed on excavation depth and burial position of pipeline. The result of the parametric study indicate that length of hyperbolic tangential function affects the results of damage assessment. Using numerical studies for buried pipeline response to ground movements by relative flexibility of the pipe-soil system. The result of numerical studies are presented in forms of design charts which can be readily used for various condition encountered in practices.

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