• The Journal of Korean Physical Therapy
• /
• v.31 no.2
• /
• pp.76-81
• /
• 2019

Purpose: This study examined the effects of squatting with different foot positions on the muscle activation of the vastus medialis oblique (VMO) and vastus lateralis (VL) muscles in subjects with genu varum. Methods: Thirty four subjects participated in this study. Surface electromyography was used to measure the muscle activation of the VMO and VL muscles at the knee angles ($15^{\circ}$, $60^{\circ}$) at three foot positions (internal rotation, neutral position, external rotation) during squatting. Results: Muscle activation differences at different knee angles and foot positions differed significantly between the VMO and VL muscles in both the varus and normal groups. In addition, there was a significant difference according to the knee angles with the foot in external rotation in the VMO and VL ratio. In the varus group, however, the VMO and VL ratio were significantly different only with the feet in internal rotation. In the muscle activation changes of the knee angle differences in the foot position, there was no significant difference in the varus group, but both the VMO and VL muscles were significant different in the normal group. Conclusion: In both groups, regardless of the foot position, muscle activation of the VMO and VL muscles increased with increasing knee flexion angle. In the normal group, when squatting with the feet in external rotation, the VMO and VL muscles activations increased with increasing knee angle. In the varus group, however, the foot position did not affect the VMO or VL muscle activation. This study shows that subjects with genu varum and normal subjects have different VMO and VL muscle activation patterns during squat exercises.

• Korean Journal of Applied Biomechanics
• /
• v.16 no.3
• /
• pp.85-94
• /
• 2006

The purpose of this study was to analyze the kinematics variables of during forehand stroke by stance patterns. Eight high school tennis players were chosen for the study, who have never been injured for last six months, in Busan. They performed horizontal swing and vertical swing that it was done each five consecutive trial in the condition of square, open and semi-open stance. It was filmed by 6 video camera and used with 3-dimensional motion analyzer system. The following kinematic variables were analyzed in relation to angle of segment( shoulder, hip and knee joint). The conclusion were as follow: 1. The angle of hip joint represented at impact that horizontal swing was not significant difference by stance patterns but vertical swing was increased in open stance than square and semi-open stance. 2. The angle of both knee was not significant difference between all stance types and swing patterns. 3. The angle of shoulder, hip and knee joint rotation showed that open stance was increased than square and semi-open stance in all swing types and event.

• The Journal of Korean Physical Therapy
• /
• v.30 no.1
• /
• pp.23-28
• /
• 2018

Purpose: This study examined the effectiveness of iliopsoas self-stretching on the hip extension angle, gluteus maximus (GM) activity, and pelvic compensated angle during prone hip extension (PHE) in subjects with iliopsoas shortness. Methods: Twenty-healthy subjects with iliopsoas shortness were recruited. Electromyography (EMG) was used to examine erector spinae (ES), multifidus (MF), GM, and biceps femoris (BF) while performing PHE. An electromagnetic tracking motion analysis device was used to measure the pelvic compensations. The pelvic compensations while performing PHE were considered to be anterior tilting and rotation. A modified Thomas test was used to monitor the hip extension angle before and after iliopsoas self-stretching. A paired t-test was used to investigate the significant difference after iliopsoas self-stretching during PHE. The level of statistical significance was set to ${\alpha}=0.05$. Results: Muscle activity of GM and hip extension angle were significantly greater after iliopsoas self-stretching compared to that before iliopsoas self-stretching during PHE (p<0.05). BF and pelvic rotation angle were significantly lower after iliopsoas self-stretching compared to that before iliopsoas self-stretching during PHE (p<0.05). The muscle activity of ES was not significantly different between PHE before and after iliopsoas self-stretching (p>0.05). Conclusion: Iliopsoas self-stretching can be effective in selectively strengthening the GM muscles with minimized pelvic compensation in subjects with iliopsoas shortness.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.27 no.7
• /
• pp.1179-1184
• /
• 2003

The technique for measuring the rotational speed of tappet in direct acting type valve train system has been developed. The optic signal monitoring system with laser and optic fiber was designed to follow the signal of tappet rotation. The system was based on ON/OFF signal generation from the additional encoder teeth under the tappet with optic fibers attached photo transistor. The data showed that tappet rotation was affected by offset, oil temperature and cam shaft operating speed. Also it was found that tappet rotation increases with oil temperature. Tappet spin was delayed 10∼s20$^{\circ}$ cam angle after valve opening. The instantaneous rotational speed of tappet was reciprocal to cam shaft speed and the tappet and the cam angle ratio was located in the range of 0.1∼0.3.

• IEIE Transactions on Smart Processing and Computing
• /
• v.1 no.2
• /
• pp.73-77
• /
• 2012

This paper reports a combined depth- and model-based face detection and tracking approach. The proposed algorithm consists of four functional modules; i) color-based candidate region extraction, ii) generation of the depth histogram for handling occlusion, iii) rotation-invariant face region detection using ellipse fitting, and iv) face tracking based on motion prediction. This technique solved the occlusion problem under complicated environment by detecting the face candidate region based on the depth-based histogram and skin colors. The angle of rotation was estimated by the ellipse fitting method in the detected candidate regions. The face region was finally determined by inversely rotating the candidate regions by the estimated angle using Haar-like features that were robustly trained robustly by the frontal face.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2008.11a
• /
• pp.385-386
• /
• 2008

Dynamic stability of the vehicle rearview mirror is an important factor for the driver's visual perception (image blur) when driving down the road and regarded as one of the vehicle level N&V performance of visible component vibration. Several projects within GM identified a set of objective metrics and validation methods that can replace current existing subjective evaluation of mirror stability. This paper presents objective evaluation results for assessing dynamic stability (angle of rotation) of the vehicle rearview mirrors using both in-lab FRF measurements and on-road testing.

• Transactions of Materials Processing
• /
• v.13 no.2
• /
• pp.142-147
• /
• 2004

Three-dimensional rigid-plastic finite element analysis has been performed to optimize open die forging process to make round bar. In the round bar forging, it is difficult to optimize process parameters in the operational environments. Therefore in this study, finite element method is used to analyze the practice of open die forging, focusing on the effects of reduction, feeding pitch and rotation angle for optimal forging pass designs. The soundness of forging process has been estimated by the smoothness and roundness of the bar at various combination of feeding pitches and rotation angles. From the test result, process conditions to make round bar having precise dimensional accuracy have been proposed.

• Journal of Korean Ophthalmic Optics Society
• /
• v.18 no.4
• /
• pp.441-447
• /
• 2013

Purpose: The present study was conducted to investigate the axial rotations of toric soft lens during the change of lens wearer's posture, and the relationship between its rotation and corneal astigmatism. Methods: The amount, direction, and speed of toric soft contact lens rotation were measured for 42 eyes (aged 20s) with the rule astigmatism in the straight and lying postures, and it compared between their changes according to corneal astigmatism. Results: There was no significant difference in the axial rotation of lens for the astigmatism prescription between the straight and lying postures. However, the rotation angle was significantly different according to the posture of lens wearer. Rotating directions in straight posture were nasal direction for 20 eyes and temporal direction for 22 eyes. In lying posture, lenses of most wearers were rotated to a direction of lying posture, and the initial rotating speed was very fast in initial wearing for -0.75 D toric lenses, but consistency for -1.25 D toric lenses. The rotation angle in lying posture showed significantly different according to the amount of corneal astigmatism, the lens speed was also significantly different according to the wearing time but not the amount of corneal astigmatism. Conclusions: The axial rotation of toric soft lens was different by the lens wearer's posture and its amount was the greater with the higher degree of corneal astigmatism. Thus, these factors should be considered for the development of toric lens design.

• Journal of the Korean Society for Precision Engineering
• /
• v.19 no.2
• /
• pp.87-94
• /
• 2002

Most of Rapid Prototyping (RP) process adopt a solid Computer Aided Design (CAD) model, slicing into thin layers of uniform, but not necessarily constant, thickness in the building direction. Each cross-sectional layer is successive1y deposited and at the same time, bonded onto the previous layers; the stacked layers form a physical part of the model. The objective of this study is to develop a method for calculating the rotation angle ($$\theta$_x, $\theta$_y$) of hotwire of the cutting system in the three-dimensional space for the Variable Lamination Manufacturing process using expandable polystyrene foam sheet (VLM-S). In order to examine the applicability of the developed method to VLM-S, various three-dimensional shapes. such as a screw, an extruded cross, and free surface bodies such as miniatures of the monkey(a figure of Sonokong), were made using the data obtained form the method.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2005.06a
• /
• pp.1438-1441
• /
• 2005

To establish of standard technique of nano-length measurement in 2D plane, new AFM system has been designed. In this system, measurement uncertainty is dominantly affected by the Abbe error of XY scanning stage. No linear stage is perfectly straight; in other words, every scanning stage is subject to tilting, pitch and yaw motion. In this paper, an AFM system with minimum offset of XY sensing is designed. And XY scanning stage is designed to minimize rotation angle because Abbe errors occur through the multiply of offset and rotation angle. To minimize the rotation angle optimal design has performed by maximizing the stiffness ratio of motion direction to the parasitic motion direction of each stage. This paper describes the design scheme of full AFM system, especially about XY stage. Full range of fabricated XY scanner is $100um\times{100um}$. And tilting, pitch and yaw motion are measured by autocollimator to evaluate the performance of XY stage. Using this AFM system, 3um pitch specimen was measured. As a result, the uncertainty of total system has been evaluated.