• Title/Summary/Keyword: Motion reduction

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Reduction of Vibration for an Elastic Structure by means of a Relocation of Part (구조 재배치를 이용한 탄성체 진동 저감)

  • Kim, Giman;Choi, Seongdae
    • Journal of the Korean Society of Manufacturing Process Engineers
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    • v.19 no.7
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    • pp.98-105
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    • 2020
  • This study deals with the passive control of the dynamic characteristics of a theoretical model which is a string with fixed ends and loaded by two point masses - a main mass (Mo) and a secondary mass (Ms). It has been controlled passively by means of a relocation of a secondary mass. A main mass placed on the string is considered as a vibrating receiver which be forced to vibrate by a vibrating source being positioned on the string. By analyzing the motion of a string, the equation of motion for a string was derived by using a method of variation of parameters. To define the optimal conditions for the vibration reduction, the governing equation, which denotes the dynamic response of a string was derived in the closed form and then evaluated numerically. The possibility of reduction of an amplitude and a power being transmitted to a main mass were found to depend on the location and the magnitude of a secondary mass as well as the range of a forcing frequency.

Intra-Motion Compensation Using CSRS method in MRI

  • Ro, Y.M.;Yi, J.H.;Cho, Z.H.
    • Journal of Biomedical Engineering Research
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    • v.15 no.4
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    • pp.377-382
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    • 1994
  • In the conventional Fourier imaging method in MRI (Magnetic Resonance Imaging), intramotion such as pulsatile flow makes zipper-like artifact along the phase encoding direction. On the other hand, line-integral projection reconstruction (LPR) method has advantages such as imaging of short T2, object and reduction of the flow artifact by elimination of the flow-induced phase fluctuation. The LPR, however, necessarily requires time consuming filtering and back-projection processes, so that the reconstruction takes long time. To overcome the long reconstruction time of the LPR and to obtain the flow artifact reduction effect, we adopted phase corrected concentric square raster sampling (CSRS) method and improved its imaging performance. The CSRS is a fast reconstruction method which has the same properties with the LPR. In this paper, we proposed a new method of flow artifact reduction using the CSRS method. Through computer simulations and experiments, we verified that the proposed method can eliminate phase fluctuations, thereby reducing the flow artifact and re- markably shorten the reconstruction time which required long time in the LPR.

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Iterated Improved Reduced System (IIRS) Method Combined with Sub-Structuring Scheme (II) - Nonclassically Damped Structural Systems - (부구조화 기법을 연동한 반복적인 동적 축소법 (II) - 비비례 감쇠 구조 시스템 -)

  • Choi, Dong-Soo;Kim, Hyun-Gi;Cho, Maeng-Hyo
    • Transactions of the Korean Society of Mechanical Engineers A
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    • v.31 no.2 s.257
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    • pp.221-230
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    • 2007
  • An iterated improved reduced system (IIRS) procedure combined with sub-structuring scheme for nonclassically damped structural systems is presented. For dynamic analysis of such systems, complex eigenproperties are required to incorporate properly the nonclassical damping effect. In complex structural systems, the equations of motion are written in the state space from. Thus, the number of degrees of freedom of the new equations of motion and the size of the associated eigenvalue problem required to obtain the complex eigenvalues and eigenvectors are doubled. Iterated IRS method is an efficient reduction technique because the eigenproperties obtained in each iteration step improve the condensation matrix in the next iteration step. However, although this reduction technique reduces the size of problem drastically, it is not efficient to apply this technique to a single domain finite element model with degrees of freedom over several thousands. Therefore, for a practical application of the reduction method, accompanying sub-structuring scheme is necessary. In the present study, iterated IRS method combined with sub-structuring scheme for nonclssically damped structures is developed. Numerical examples demonstrate the convergence and the efficiency of a newly developed scheme.

Flicker Reduction in Image Sequences (영상 시퀀스의 플리커 제거)

  • Lee, Im-Geun
    • Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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    • 2010.05a
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    • pp.577-580
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    • 2010
  • This paper proposes a new algorithm for flicker reduction. Flicker is defined as unwanted luminance fluctuation in the image sequences. As the flicker degrades the performance of motion estimation or segmentation of the objects, it should be corrected before further processing. In this paper, we model the flicker effects as a linear system with gain and offset parameter and propose the new algorithm for flicker reduction. The proposed algorithm considers gain and offset parameter separately, and stabilizes the luminance fluctuation based on these parameters. We show the performance of the proposed method by testing on the sequence with artificially added luminance flicker and real sequence with object motion.

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Effects of Korean Medicine on Post-rotator Cuff Surgery Patients : A Retrospective Observational Study (회전근개 파열 수술 후 환자에 대한 한의학적 치료 효과 : 후향적 관찰연구)

  • Park, Jeong Wook;Oh, Min Seok
    • Journal of Physiology & Pathology in Korean Medicine
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    • v.33 no.4
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    • pp.233-238
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    • 2019
  • The aim of this study was to investigate the effect of Korean medicine treatments on pain reduction and functional improvement of patients after rotator cuff surgery. We studied 10 patients who had admitted to Dunsan Korean Medical hospital after have being diagnosed as rotator cuff tear and got a surgery at other hospital from April 30, 2014 to April 30, 2019. This study was conducted as retrospective study which analyzes patient's medical records. Statistical analysis was performed using the IBM SPSS statistics 24 program. We used Numeric Rating Scale to evaluate pain reduction, Range of Motion to evaluate shoulder functional improvement and Five-point likert scale to evaluate the patient's satisfaction. The result showed that Korean medicine treatments statistically significantly reduced pain on the patients after rotator cuff surgery. Although there were improvement of Range of Motion, it wasn't statistically significant. In conclusion, we found that the Korean medicine treatments showed a positive effect on pain reduction of patients after rotator cuff surgery and got a high satisfaction.

An Experimental Study on the Behavior of Open-ended Pipe Piles Ggroup to the Simulated Seaquake (해진시 개단무리말뚝의 거동에 관한 모형실험 연구)

  • 남문석;최용규;김재현
    • Proceedings of the Korean Geotechical Society Conference
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    • 1999.03a
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    • pp.447-454
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    • 1999
  • The compressive capacity and the soil plugging resistance of single open-ended pipe pile were completely decreased in the previous study on the behavior of shorter single pile during simulated seaquake induced by the vertical component of earthquake. But the capacity of single open-ended pipe pile with greater penetration and the capacity of piles group with shorter penetration were expected to be stable after seaquake motion. In this study, first, 2-piles or 4-piles are driven into the calibration chamber included in saturated fine medium sand with several simulated penetrations, and the compressive load test for each piles group was performed. Then, about 95 % compressive load of the ultimate capacity was applied on the pile head during the simulated seaquake motion. Finally, In confirm the reduction of pile capacity during the simulated seaquake motion, the compressive load test for each single pile or piles group after seaquake motion was performed. During the simulated seaquake, the compressive capacity of open-ended pipe piles with greater penetration ( 〉about 27 m) was not degraded even in deep sea deeper than 220 m and soil plug within open-ended pipe pile installed in deep sea was stable after seaquake motion. Also, in the case of 2-piles or 4-pile groups, the compressive capacity after seaquake motion was not degraded at all regardless of pile penetration depth beneath seabed, sea water depth and seaquake frequency.

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Field Mismatch Compensation and Motion Blur Reduction System for Moving Images (동영상의 필드불일치 보정 및 움직임열화 제거 시스템 개발)

  • Choung, Yoo-Chan;Paik, Joon-Ki
    • Journal of the Korean Institute of Telematics and Electronics S
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    • v.36S no.2
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    • pp.81-87
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    • 1999
  • In this research, we propose a field mismatch compensation method for interlaced scan image and a image restoration technique for removing motion blur. In order to compensate field mismatch, the edge classification-based linear interpolation technique and the method using the object-based motion compensation are described. We also propose an edge estimation method and an motion-based image segmentation algorithm. For removing motion blur, we adopt an adaptive iterative image restoration method using the motion-based segmentation result to improve the quality of restored image.

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Fast Motion Estimation Using Adaptive Search Range for HEVC (적응적 탐색 영역을 이용한 HEVC 고속 움직임 탐색 방법)

  • Lee, Hoyoung;Shim, Huik Jae;Park, Younghyeon;Jeon, Byeungwoo
    • The Journal of Korean Institute of Communications and Information Sciences
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    • v.39A no.4
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    • pp.209-211
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    • 2014
  • This paper proposes a fast motion estimation method which can reduce the computational complexity of HEVC encoding process. While the previous method determines its search range based on a distance between a current and a reference pictures to accelerate the time-consuming motion estimation, the proposed method adaptively sets the search range according to motion vector difference between prediction units. Experimental results show that the proposed method achieves about 10.7% of reduction in processing time of motion estimation under the random access configuration whereas its coding efficiency loss is less than 0.1%.

Modeling and Simulation of the 6 DOF Motion of a High Speed Planing Hull Running in Calm Sea (정수중을 활주하는 고속선의 6자유도 운동 모델링 및 시뮬레이션)

  • Yoon, Hyeon Kyu;Kang, Namseon
    • Journal of the Society of Naval Architects of Korea
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    • v.53 no.1
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    • pp.10-17
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    • 2016
  • When a planing hull straightly runs and turns, its floating position and pitch angle are changed depending on its speed, and large transient motion happens. In this paper, six degrees of freedom(6 DOF) equations of motion, which could simulate the motion of a planing hull, are established. Static and dynamic forces in vertical plane are modeled using pre-calculated displacements and metacentric heights depending on various draft, lift under bottom, and vertical damping coefficients which are used to tune the final motion. Hydrodynamic coefficients in horizontal plane at various equilibrium state are calculated by using Lewandowski's empirical formula and the speed-dependent equilibrium state are calculated beforehand by Savitsky's formula. The speed effects are considered by curve-fitting the coefficients at various speed to the polynomials. Accelerating, decelerating and backing, turning, and zig-zag are simulated and compared with the sea trial results, and it is confirmed that the speed reduction, roll, and pitch during such maneuvers of sea trial and simulation are well consistent.

Clinical Application and Limitations of the Capsular Pattern (관절낭 패턴의 임상적 적용과 한계)

  • Lim, Wootaek
    • Physical Therapy Korea
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    • v.28 no.1
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    • pp.13-17
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    • 2021
  • A normal range of motion is essential for performing activities of daily living. The capsular pattern is the proportional motion restriction in range of motion during passive exercises due to tightness of the joint capsule. Although the capsular pattern is widely referred to in clinical practice, there is no scientific evidence to support the concept. In this review, the appropriateness of the capsular pattern for evaluation of joint pathology was assessed. In the Textbook of Orthopaedic Medicine written by Cyriax, the capsular pattern did not specify how much reduction in angular motion is considered motion restriction. As the definition proposed initially was unclear, different methods have been used in previous studies investigating capsular pattern. In addition, the capsular pattern described all the major joints of the human body, but only the hip joint, knee joint, and shoulder joint were studied in experimental studies. Sensitivity and specificity were reported in one study and were meaningful in specific pathologies (loss of extension to loss of flexion). There was no consensus on the reliability and validity. In summary, the capsular pattern suggested by Cyriax or Kaltenborn is not supported or applies only to certain conditions. Various components around a joint complement each other and provide stability to the joint. It is recommended that the therapist perform multiple assessments rather than rely on a single assessment when evaluating joints.