• Journal of Korean Physical Therapy Science
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• v.14 no.1_4
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• pp.1-10
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• 2007

The purpose of this study was to find the effects of the lumbar stabilizing exercise on the isometric lumbar extension strength and the range of motion of lumbar extension. 16 healthy subjects were recruited (9 males, 7 females, mean age 25${\pm}$3.2). They performed 5 types of exercises 5 times per week for 4 weeks. We evaluated isometric trunk extension strength (0, 12, 24, 36, 48, 60, $72^{\circ}$) by MedX(Ocala, FL) and measured range of motion of lumbar extension. All measurements were measured at pre-exercise and 4 weeks post-exercise. The results of this study were summarized as follows; After 4 weeks of exercise, isometric lumbar extension strength was generally increased but there were only significant differences at $12^{\circ},\;24^{\circ},\;48^{\circ}$. The range of motion of lumbar extension was increased (p<.05). The isometric lumbar extension strength correlated with the range of motion of lumbar extension. In conclusion, our results have shown that lumbar stabilizing exercise influenced both lumbar extension strength and range of motion of lumbar extension.

• International Journal of Fluid Machinery and Systems
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• v.4 no.3
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• pp.341-348
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• 2011

The study of bacterial flagellar swimming motion remains an interesting and challenging research subject in the fields of hydrodynamics and bio-locomotion. This swimming motion is characterized by very low Reynolds numbers, which is unique and time reversible. In particular, the effect of rotation of helical flagella of bacterium on swimming motion requires detailed multi-disciplinary analysis. Clear understanding of such swimming motion will not only be beneficial for biologists but also to engineers interested in developing nanorobots mimicking bacterial swimming. In this paper, computational fluid dynamics (CFD) simulation of a three dimensional single flagellated bacteria has been developed and the fluid flow around the flagellum is investigated. CFD-based modeling studies were conducted to find the variables that affect the forward thrust experienced by the swimming bacterium. It is found that the propulsive force increases with increase in rotational velocity of flagellum and viscosity of surrounding fluid. It is also deduced from the study that the forward force depends on the geometry of helical flagella (directly proportional to square of the helical radius and inversely proportional to pitch).

• Journal of Korean Society of Water and Wastewater
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• v.31 no.1
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• pp.13-19
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• 2017

Relatively low efficiency in anaerobic digestion process is mainly caused by unproper mixing method. In this study, tray motion type agitator was applied in actual anaerobic digestion tank in order to improve the digestion efficiency, equalize the flow velocity distribution and energy saving. The impeller of tray motion type agitator was reciprocated vertically. Gas lift type agitator and tray motion type agitator appears almost same mixing efficiency include digestion rates. However, tray motion type agitator have shown that lower energy consumption compared to the conventional gas lift type agitator. Implementation of tray motion type agitator in the anaerobic digestion tanks contributed to the stabilization of mixing environment, efficiency and energy efficiency of the tank.

• Journal of the Korea Institute of Military Science and Technology
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• v.15 no.3
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• pp.257-265
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• 2012

This paper presents a study on characteristics of precession motion of a smart munition. It's a kind of the Sensor Fuzed Weapon. The particular thing for the smart munition is that it has precession motion in the air while the sensor is searching the ground to detect ground vehicles such as tanks. The smart munition has a cylindrical shape and has a sensor attached on its side. Due to its non-uniform mass distribution, its center of gravity(CG) is located away from the center of volume(CV). In order for the smart munition to detect the target effectively, the ground searching pattern of sensor should have an uniform circular form, and for this, the precession motion of smart munition should be in its steady-state. Finally, it is necessary to choose the right initial conditions at the moment of firing, for the steady-state precession motion during flight.

• Journal of Korean Institute of Industrial Engineers
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• v.9 no.2
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• pp.9-25
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• 1983

The purpose of this study was to film up computerized analyses for both kinematic posture(film analysis) and muscle dynamics (EMG) during a weight-lifting motion. (Snatch, Clean and Jerk) Using a motor drive camera (3.5 frames/sec) and a Location Analyzer, motion tracks of 13 landmarks, which were attached to the major joints, during the motion were converted into digital values. At the same time, EMG amplitudes from 11 major muscle groups were recorded. Recorded data were processed via analog/hybrid computer (ADAC 480) and digital computer (PDP 11/44). Landmark locations and EMG amplitude were integrated by a computerized routine. Computer output included graphic reproductions on sepuential dislocations of body segments, center of gravity of body segments and the associated changes on EMG amplitude such as % EMG's of major muscle group during a weight lifting motion. The results strongly suggest that the computerized motion-EMG integration can provide a further working knowledge in selection and in training of workers and athletes. Suggestions for a further study include additional device for velocity measurement, expansion of the link model for biomechanical analysis and other implementations necessary for athletic application.

• Structural Engineering and Mechanics
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• v.53 no.5
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• pp.957-979
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• 2015

The present paper investigates the influence of the orientation of the ground-motion reference axes, the seismic incident angle and the seismic intensity level on the inelastic response of asymmetric reinforced concrete buildings. A single storey asymmetric building is analyzed by nonlinear dynamic analyses under twenty bi-directional ground motions. The analyses are performed for many angles of incidence and four seismic intensity levels. Moreover three different pairs of the horizontal accelerograms corresponding to the input seismic motion are considered: a) the recorded accelerograms, b) the corresponding uncorrelated accelerograms, and c) the completely correlated accelerograms. The nonlinear response is evaluated by the overall structural damage index. The results of this study demonstrate that the inelastic seismic response depends on the orientation of the ground-motion reference axes, since the three individual pairs of accelerograms corresponding to the same ground motion (recorded, uncorrelated and completely correlated) can cause different structural damage level for the same incident angle. Furthermore, the use of the recorded accelerograms as seismic input does not always lead to the critical case of study. It is also shown that there is not a particular seismic incident angle or range of angles that leads to the maximum values of damage index regardless of the seismic intensity level or the ground-motion reference axes.

• Journal of Korea Multimedia Society
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• v.23 no.1
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• pp.15-23
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• 2020

Recently, the increase in the elderly population due to an aging society has led to a relative increase in senile diseases such as vascular dementia or Alzheimer's disease, and the social burden for rehabilitation has increased. In addition, studies have been conducted for the risk assessment and prevention of musculoskeletal disorders. The purpose of this study is to suggest a system that can be used to help with dementia prevention training by tracking the movement of motion and virtual reality contents for the risk factors of musculoskeletal disorders of the elderly. We propose a training method for preventing dementia through musculoskeletal motion analysis algorithm and virtual reality content. Through motion recognition algorithm based on motion region design, we will track and analyze the moving radius of the target joint. The purpose of this study is to calculate and evaluate scores based on the time to accomplish the goals on virtual reality contents for the prevention of musculoskeletal disorders and the support of dementia prevention training, and the degree of difficulty, and to analyze the correlation between the results of performing K-MMSE and VR contents.

• Journal of Applied Reliability
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• v.16 no.2
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• pp.147-154
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• 2016

Purpose: To evaluate statistical differences among three measurements of range of motion (ROM) with Rapael Smart Glove (RSG) group 1, 2 and manual goniometer group. To investigate reference value of the kinematic analysis for range of motion (ROM) of distal upper extremity with Rapael Smart Glove (RSG). Methods: Sixteen normal persons without limitation of motion (LOM) enrolled in the study. The study was performed at two separate times and by two investigators on 16 normal adults. We compared ROM with RSG for measuring joint angles. We compared degrees of forearm supination/pronation, wrist flexion/extension and radial deviation/ulnar deviation during ROM of 16 participants using RSG. After one week, degrees of each motion were measured in the same way by other investigator to evaluate the reliability. Results: Statistical differences among three groups were showed. Most results of paired t-test between two RSG groups were over 0.05 and exceptions are supination, extension, and finger %. Conclusion: Our findings demonstrate that ROM of normal persons obtained by kinematic analysis with RSG are not valid as normal reference value for distal upper extremity motion. But, the reliability of between two RSG groups was showed with paired t-test and Pearson's correlation except supination, extension and finger %.

• Journal of International Academy of Physical Therapy Research
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• v.3 no.1
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• pp.364-369
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• 2012

The purpose of this study was to analyze lower limb muscle activity and 3D motion analysis according to change foot arch height during walking. We selected 9 young and healthy people who have been normal foot. And we selected 7 young and healthy people who have been flatfoot. So, people were divided into 2 groups and walked platform during 2 minutes twice for checked by 3D motion analysis. These data were characterized by EMG measurements of three muscles( tibialis anterior, medial and lateral gastrocnemius) while they were walking. The collected data were analyzed by Independent t test using the SPSS statistics program(Ver 12.0). In foot arch change, there were no significant difference in three muscles 3D motion analysis also found that there were no significant difference in joint angles. In this study was to analyze lower limb muscle activity and 3D motion analysis according to change foot arch, but there were no significant difference in 6 muscles neither joint angles.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 1995.10a
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• pp.185-190
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• 1995

In recent years, many researcher have been interested in the stability of a thin beam. Among them, Pai and Nayfeh[1] had investigated the nonplanar motion of the cantilever beam under lateral base excitation and chaotic motion, but this study is associated with internal resonance, i.e. one to one resonance. Also Cusumano[2] had made an experiment on a thin beam, called Elastica, under bending loads. In this experiment, he had shown that there exists out-of-plane motion, involving the bending and the torsional mode. Pak et al.[3] verified the validity of Cusumano's experimental works theoretically and defined the existence of Non-Local Mode(NLM), which is came out due to the instability of torsional mode and the corresponding aspect of motions by using the Normal Modes. Lee[4] studied on a thin beam under bending loads and investigated the routes to chaos by using forcing amplitude as a control parameter. In this paper, we are interested in the motion of a thin beam under torsional loads. Here the form of force based on the natural forcing function is used. Consequently, it is found that small torsional loads result in instability and in case that the forcing amplitude is increasing gradually, the motion appears in the form of dynamic double potential well, finally leads to complex motion. This phenomenon is investigated through the poincare map and time response. We also check that Harmonic Balance Method(H.B.M.) is a suitable tool to calculate the bifurcated modes.