• Journal of the Korean Society of Visualization
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• v.7 no.1
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• pp.21-28
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• 2009

The study of swirling flow is of technical and scientific interest because it has an internal recirculation field, and its tangential velocity is related to the curvature of streamline. The fluid flow for tubes and elbow of heat exchangers has been studied largely through experiments and numerical methods, but studies about swirling flow have been insufficient. Using the particle image velocimetry(PTV) method, this study found the time averaged velocity distribution with swirl and without swirl along longitude sections and the results appear to be physically reasonable. In addition, streamwise mean velocity distribution was compares with that of other. Furthermore, other experimental investigation was performed to study the characteristics of turbulent water flow in a horizontal circular tube by using liquid crystal. 2D PIV technique is employed for velocity measurement and liquid crystal is used for heat transfer experiments in water. Temperature visualization was made quantitatively by calibrating the colour of the liquid crystal versus temperature using various approaches.

• Journal of the Ergonomics Society of Korea
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• v.5 no.1
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• pp.29-41
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• 1986

This study intends to improve the efficiencies of school works by proposing a method of determining the standard sizes of chairs and desks. To achive this purpose, eight measurements were taken of 1248 school children. The main results drawn from this study are : 1. There are significant correlations between stature and popliteal height and between stature and elbow height (seated). 2. There are significant differences between men and women of similar stature in respect of popliteal height. 3. The standard sizes of chairs and desks ought to be based on the characteristics of human body size and their relationship.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.1
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• pp.36-41
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• 2002

The cause and the elimination method for the chattering phenomena were investigated in a check valve attached to the exit of an auxiliary cooling water pump in a Korean nuclear powerplant. From the site experiment and the numerical calculation, the incident angle of the disk was so small that it was not able to produce the sufficient lifting force to overcome the gravitational component of the disk weight. Moreover, it turned out that the installation position was not symmetric for the secondary vortical flow generated inside the elbow so that the flow structure had strongly unstable flow characteristics. From this study, the tapping noise and the chattering phenomena were eliminated exactly by changing the incidence angle of the valve disk and the installation position of the calve body.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1848-1853
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• 2000

Cause and the elimination method for the chattering phenomena were investigated the check valve attached exit of the auxiliary cooling water pump at a korean nuclear powerplant. From the site experiment and numerical calculation the incident angle of the disk was so small that it was not able to produce the lifting force to overcome the component of disk weight. Moreover, it turned out that the installed position was not symmetric for the secondary vortical flow generated inside the elbow, so that the flow structure had strongly unstable flow characteristics. From this technical support, the tapping noise and the chattering phenomena were eliminated exactly by changing the incidence angle of the valve disk and installed position of the check valve.

• Korean Journal of Applied Biomechanics
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• v.30 no.3
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• pp.225-234
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• 2020

Objective: The purpose of this study was to investigate the kinematic sequence patterns according to movement times during Karate choku-tsuki. Method: Ten Korea national Karate athletes participated in this study. Participants asked to perform jodan and chudan choku-tsuki. 30 infrared cameras were used to measure angular kinematic of elbow, shoulder, trunk, pelvis, hip, knee, ankle. Results: The two-way repeated measures ANOVA revealed significant effects for the joints (p<.05). But no significant effect for the movement time and interaction of joints x movement time existed for the kinematic sequence variables. Conclusion: For karate kumite players to reduce the movement time of punch, it is necessary to train kinematic sequences that allow each joint to rotate at a relatively similar timing.

• Korean Journal of Occupational Health Nursing
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• v.18 no.2
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• pp.270-280
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• 2009

Purpose: This study was conducted to examine the relationship between job stress and work-related musculoskeletal symptoms of hospital nurses. Method: The questionnaires were administered to 290 nurses working in a general hospital located in S city from September 1 to 15, 2008. The data were analysed with descriptive statistics, and logistic regression test by SPSS WIN 14.0. Results: With the NIOSH criteria 1, the musculoskeletal symptoms were prevalent in 66.8% of the subjects. The musculoskeletal symptoms by body parts appeared mostly on leg/foot(40.6%) and followed by shoulder (38.7%), waist(30.3%), neck(23.6%), hand/wrist/finger(14.0%) and arm/elbow(4.4%). There were statistically significant differences in prevalence rate of musculoskeletal symptoms by age, work department, career and job stress. Conclusion: When developing a management program for musculoskeletal symptoms of hospital nurses, it is necessary to fully understand nurses' work considering each hospital's nursing administration system.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2009.01a
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• pp.764-767
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• 2009

Motion capture systems allow to measure the precise position of markers on the human body in real time. These captured motion data, the marker position data, have to be fitted by a human skeleton model to represent the motion of the human. Typical human skeleton models approximate the joints using a ball joint model. However, because this model cannot represent the human skeleton precisely, errors between the motion data and the movements of the simplified human skeleton model happen. We propose in this paper a method for measuring a translation component of wrist, and elbow joints on upper limb using optical motion capture system. Then we study the errors between the ball joint model and acquired motion data. In addition, we discuss the problem to estimate motion of human joint using optical motion capture system.

• Proceedings of the KSME Conference
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• 2004.04a
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• pp.96-101
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• 2004

Cast austenitic stainless steel is used for several components, such as primary coolant piping, elbow, pump casing and valve bodies in light water reactors. These components are subject to thermal embrittlement at the reactor operating temperature. The objective of this study is to summarize the method of estimating ferrite content, Charpy impact energy and J-R curve and to evaluate the thermal embrittlement of the cast austenitic stainless steel piping used in the domestic nuclear power plants. The result of evaluation, two domestic nuclear power plants used CF-8M and CF-8A material has adequate fracture toughness after saturation.

• Journal of the Korean Society of Safety
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• v.17 no.4
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• pp.178-183
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• 2002

The purpose of this study was to quantitatively investigate the effects of external load upper extremity posture on perceived discomfort. An experiment was conducted for measuring discomfort scores depending upon external loads and upper extremity postures, in which the free modules and numeric estimate method of the magnitude estimation was adopted as a tool for obtaining discomfort ratings. The upper extremity postures were controlled by wrist flexion/extension, elbow foexion, shoulder flexion, and shoulder adduction/abduction. The results showed that all experimental variables except shoulder adduction/abduction were significant at ${\alpha}$=0.01 or 0.05. The effect of external load was very much larger than that of upper extremity postures. Therefore, it is recommended that a new posture classification scheme taking effect of external load to into consideration be developed for quantifying postural load.

• Journal of Biomedical Engineering Research
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• v.32 no.2
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• pp.118-126
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• 2011

This study proposes a human body orientation tracking system by inertial and earth magnetic sensors. These sensors were fused by indirect Kalman filter. The proposed tracking system was configured and the filter was implemented. The tracking performance was evaluated with static and dynamic tests. In static test, the sensor was fixed on the floor while its static characteristics was analyzed. In dynamic test, the sensor was held and moved manually for 30 seconds. The dynamic test included x, y, z axis rotations, and elbow flection/extension motions that mimic drinking. For these dynamic motions, the tracking angle error was under $4.1^{\circ}$ on average. The proposed tracking method is expected to be useful for various human body motion analysis.