• Journal of the Korean Society for Precision Engineering
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• v.17 no.8
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• pp.120-125
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• 2000

This paper proposes a tilt sensor made by MEMS technology. The sensor consists of an electrode glass a small mercury drop a circular channel and a cover glass. The mercury drop is used as medium of a current flow and in contact with two circular chromel electrodes used as an angular-motion resistance When this sensor inclines the mercury drop inside the circular channel moves into the bottom under the influence of gravity. A tilt angle can be measured by changed resistance as tilting this sensor, This sensor has a linear section between +50.$^{\circ}$ and -50.$^{\circ}$ with the accuracy of 2.$^{\circ}$. We are also studying about the enlargement of the linear section and the effect of the size of the mercury drop.

• Journal of International Academy of Physical Therapy Research
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• v.10 no.4
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• pp.1868-1872
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• 2019

Background: Lower trapezius muscle function is important for the prevention and treatment of shoulder injuries. However, scapular posterior tilt movement has been overlooked in lower trapezius strengthening exercise programs. Objective: To examine the effects of prone arm lifting with scapular posterior tilt (PALSPT) on trapezius muscles. Design: Crossover study Methods: 17 healthy males were recruited for participation in this study. Participants performed backward rocking diagonal arm lifting (BRDAL) and PALSPT. To train participants in scapular posterior tilt movements for PALSPT, visual biofeedback of scapular movements was provided using a motion sensor. Electromyography (EMG) activities of the middle and lower trapezius were recorded using a surface EMG system. Differences in middle and lower trapezius muscle activity between BRDAL and PALSPT exercises were analyzed. Results: Lower trapezius muscle activity was significantly greater during PALSPT than during BRDAL (p=.006). Although greater EMG activity was observed in the middle trapezius during PALSPT than during BRDAL, this difference was not significant (p=.055). Conclusions: The results of the present study indicate that scapular posterior tilt movements must be considered in lower trapezius muscle strengthening programs.

• The Journal of Korean Physical Therapy
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• v.30 no.1
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• pp.14-22
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• 2018

Purpose: This study examined the effects of the lower limb alignment on the pelvis, hip, and knee kinematics in people with genu varum during stair walking. Methods: Forty subjects were enrolled in this study. People who had intercondylar distance ${\geq}4cm$ were classified in the genu varum group, and people who had intercondylar distance <4cm and intermalleolar distance <4cm were placed in the control group. 3D motion analysis was used to collect the pelvis, hip, and knee kinematic data while subjects were walking stairs with three steps. Results: During stair ascent, the genu varum group had decreased pelvic lateral tilt and hip adduction at the early stance phase and decreased pelvic lateral tilt at the swing phase compared to the control group. At the same time, they had decreased minimal hip adduction ROM at the early stance and decreased maximum pelvic lateral tilt ROM and minimum hip rotation ROM at the swing phase. During stair descent, the genu varum group had decreased pelvic lateral tilt at the early stance and decreased pelvic lateral tilt and pelvic rotation at the swing phase. In addition, they had decreased pelvic frontal ROM during single limb support and increased knee sagittal ROM during the whole gait cycle. Conclusion: This study suggests that a genu varum deformity could affect the pelvis, hip and knee kinematics. In addition, the biomechanical risk factors that could result in the articular impairments by the excessive loads from lower limb malalignment were identified.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1996.11a
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• pp.333-337
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• 1996

The spindle directly affects parts accuracy during machining, or work piece in machine tools. In this paper a comprehensive study is performed combined mr performance of machine tool spindle. The developed methology has been practically applied to a spindle of machine tools.

• Journal of the Korean Society for Precision Engineering
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• v.27 no.2
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• pp.145-152
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• 2010

Gait phase detection is important for evaluating the recovery of gait ability in patients with paralysis, and for determining the stimulation timing in FES walking. In this study, three different motion sensors(tilt sensor, gyrosensor and accelerometer) were used to detect gait events(heel strike, HS; toe off, TO) and they were compared one another to determine the most applicable sensor for gait phase detection. Motion sensors were attached on the shank and heel of subjects. Gait phases determined by the characteristics of each sensor's signal were compared with those from FVA. Gait phase detections using three different motion sensors were valid, since they all have reliabilities more than 95%, when compared with FVA. HS and TO were determined by both FVA and motion sensor signals, and the accuracy of detecting HS and TO with motion sensors were assessed by the time differences between FVA and motion sensors. Results show of that the tilt sensor and the gyrosensor could detect gait phase more accurately in normal subjects. Vertical acceleration from the accelerometer could detect HS most accurately in hemiplegic patient group A. The gyrosensor could detect HS and TO most accurately in hemiplegic patient group A and B. Valid error ranges of HS and TO were determined by 3.9 % and 13.6 % in normal subjects, respectively. The detection of TO from all sensor signals was valid in both patient group A and B. However, the vertical acceleration detected HS validly in patient group A and the gyrosensor detected HS validly in patient group B. We could determine the most applicable motion sensors to detect gait phases in hemiplegic patients. However, since hemiplegic patients have much different gait patterns one another, further experimental studies using various simple motion sensors would be required to determine gait events in pathologic gaits.

• Physical Therapy Korea
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• v.18 no.1
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• pp.9-17
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• 2011

The purpose of this study was to assess visual biofeedback's influence on trunk muscles' (EMG) activity and endurance holding time for correct position during whole-body tilt exercise. For the study, we recruited 14 volunteers who showed no symptom of lumbar disease during medical tests. We measured the EMG activity of their rectus abdominis, external abdominal oblique, internal abdominal oblique and erector spinae muscles, and their endurance holding time for correct position during $40^{\circ}$ anterior and posterior whole-body tilt under two conditions: whole-body tilt with and without visual biofeedback. Resistance with gravitational force on the trunk during whole-body tilt was applied by using a device that had a monitor on which the subjects could check their alignment and that sounded an alarm if a subject's alignment collapsed. The study showed an increase in the EMG activity of external abdominal oblique, internal abdominal oblique/rectus abdominis ratio and endurance holding time for correct position during both $40^{\circ}$ anterior and posterior whole-body tilt with visual biofeedback compared with without visual biofeedback (p<.05). We suggest that the whole-body tilt exercise with visual biofeedback could be a beneficial strategy for selectively strengthening the internal abdominal oblique muscle and minimizing the rectus abdominis muscle's activity while maintaining correct alignment during whole-body tilt exercise.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.21 no.1
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• pp.3-8
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• 2011

This paper introduces a robot eye module, of which two degree-of-freedom motions, i.e. panning and tilting, are driven by a pair of wires. The main feature of the module is that each wire can generate push-pull motion without buckling. It is thanks to a Teflon tube which guides the path of the moving wire. End points of the tube and wire have pivot elements so that a smooth push-pull motion is produced even when the end point of wire is moved by eye rotation. This mechanism helps the eye module to be very compact. In this paper, the structure of the robot eye module is introduced in detail, and the required motor angles for a certain direction of eye line are investigated analytically and experimentally.

• Proceedings of the Korea Contents Association Conference
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• 2004.05a
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• pp.396-400
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• 2004

In this study, we have proposed the tracking system of single moving object. The tracking system was estimated motion using differential image, and than track the moving object by controlled Pan/Tilt device of camera. Proposed tracking system is devided into image acquisition and preprocessing phase, motion estimation phase and object tracking phase. To estimation the motion, differential image method was used. In the binary differential image, decision of threshold value was used adaptive method. And in grouping the object area, block_based recursive labeling algorithm was used. As a result of experiment, motion of moving object can be estimated. The result of tracking, object was not lost and object was tracked correctly.

• Journal of Information Display
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• v.6 no.4
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• pp.16-25
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• 2005

In this paper, a new 3D object tracking system using the disparity motion vector (DMV) is presented. In the proposed method, the time-sequential disparity maps are extracted from the sequence of the stereo input image pairs and these disparity maps are used to sequentially estimate the DMV defined as a disparity difference between two consecutive disparity maps Similarly to motion vectors in the conventional video signals, the DMV provides us with motion information of a moving target by showing a relatively large change in the disparity values in the target areas. Accordingly, this DMV helps detect the target area and its location coordinates. Based on these location data of a moving target, the pan/tilt embedded in the stereo camera system can be controlled and consequently achieve real-time stereo tracking of a moving target. From the results of experiments with 9 frames of the stereo image pairs having 256x256 pixels, it is shown that the proposed DMV-based stereo object tracking system can track the moving target with a relatively low error ratio of about 3.05 % on average.

• Journal of the Korean Society for Precision Engineering
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• v.22 no.9 s.174
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• pp.77-84
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• 2005

In most vision applications, we are frequently confronted with determining the position of object continuously. Generally, intertwined processes ire needed for target tracking, composed with tracking and control process. Each of these processes can be studied independently. In case of actual implementation we must consider the interaction between them to achieve robust performance. In this paper, the robust real time visual tracking in complex background is considered. A common approach to increase robustness of a tracking system is to use known geometric models (CAD model etc.) or to attach the marker. In case an object has arbitrary shape or it is difficult to attach the marker to object, we present a method to track the target easily as we set up the color and shape for a part of object previously. Robust detection can be achieved by integrating voting-based visual cues. Kalman filter is used to estimate the motion of moving object in 3D space, and this algorithm is tested in a pan/tilt robot system. Experimental results show that fusion of cues and motion estimation in a tracking system has a robust performance.