• Journal of The Korean Society of Integrative Medicine
• /
• v.7 no.1
• /
• pp.81-88
• /
• 2019

Purpose : The purpose of this study was to examine if there is any correlation between pelvic tilt angle and trunk motion and trunk extensor during trunk forward flexion and to measure trunk motion, onset time of trunk motion, and onset time of trunk extensor activation. Methods : The subjects of this study were 42 healthy adults. The subjects had no back pain due to neurological disease and no experience of back surgery. After pelvic tilt angle was measured, each trunk forward flexion was performed three times. Trunk motion and onset time of trunk motion were measured using Myomotion. Four sensors were used, with one located at the upper thoracic (below $C_7$), the lower thoracic ($T_{12}-L_1$), the sacrum ($S_1$), and at the center of the anterior femur. Onset time of trunk extensors (spinalis, longissimus, gluteus medius, gluteus maximus, biceps femoris, and gastrocnemius) activation was measured using a wireless surface EMG. The EMG amplitude was normalized by using the reference voluntary contraction (RVC). The statistical significance of the results were evaluated using Pearson's correlation test. Results : The correlation between pelvic tilt angle and lumbar motion, onset time of pelvis motion, and onset time of gluteus medius activation was statistically significant in a positive direction (p<.05). The correlation between pelvic tilt angle with pelvis motion, onset time of lumbar motion, and onset time of longissimus activation showed a statistically significant negative correlation (p<.05). Conclusion : The study results provide a significant contribution to our understanding of the lumbar load at the initial stage of trunk flexion. Therefore, it may be possible to provide basic data for evaluation and treatment, such as orthodontic treatment for alignment of the spine and back pain. In addition, it is necessary to focus on normal exercise pattern reeducation as well as pelvic correction during exercise in daily life or in industrial fields.

• 제어로봇시스템학회:학술대회논문집
• /
• 1996.10b
• /
• pp.367-370
• /
• 1996

This study deals with the motion modeling by the unit motion of robots and the work measurement through classification of robot motions and standardization. The proposed approach is to scrutinize the Predetermined Time Standards(PTS) methods for measurement of manual tasks performed by people and the basic motions for accomplishing that tasks. And then, it constructs the unit motion models as subsets composed with the basic motions. It apply together with movements distance as a time variable, too. These results are used for the work measurements of robots by the unit motion models.

• Journal of the Ergonomics Society of Korea
• /
• v.8 no.1
• /
• pp.41-46
• /
• 1989

The purpose of this study is to improve robot motion control in teaching and operating the expert system/world coordinate system (TOES/WCS) constructed in the previous study. The major contribution of this study is reduction of the inaccuracy in coordinated reading and the movement time of robots in macro motion control. This study also reduces undesirable time of micro motion control by using an unit control (UC) and a micro unit control (MUC) in micro motion control.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.28 no.5
• /
• pp.233-247
• /
• 2024

The damage to structures during an earthquake can be varied depending on the frequency characteristics of seismic waves and the geological properties of the ground. Therefore, considering such attributes in the design ground motions is crucial. The Korean seismic design standard (KDS 17 10 00) provides design response spectra for various ground classifications. If required for time-domain analysis, ground motion time series can be either selected and adjusted from motions recorded at rock sites in intraplate regions or artificially synthesized. Ground motion time series at soil sites should be obtained from site response analysis. However, in practice, selecting suitable ground motion records is challenging due to the overall lack of large earthquakes in intraplate regions, and artificially synthesized time series often leads to unrealistic responses of structures. As an alternative approach, this study provides a case study of generating ground motion time series based on the hybrid broadband ground motion simulation of selected scenario earthquakes at sites in the Nakdonggang delta region. This research is significant as it provides a novel method for generating ground motion time series that can be used in seismic design and response analysis. For large-magnitude earthquake scenarios close to the epicenter, the simulated response spectra surpassed the 1000-year design response spectra in some specific frequency ranges. Subsequently, the acceleration time series at each location were used as input motions to perform nonlinear 1D site response analysis through the PySeismoSoil Package to account for the site response characteristics at each location. The results of the study revealed a tendency to amplify ground motion in the mid to long-period range in most places within the study area. Additionally, significant amplification in the short-period range was observed in some locations characterized by a thin soil layer and relatively high shear wave velocity soil near the upper bedrock.

• Korean Journal of Computational Design and Engineering
• /
• v.19 no.1
• /
• pp.68-79
• /
• 2014

Human model simulation has been widely used in various industrial areas such as ergonomic design, product evaluation and characteristic analysis of work-related musculoskeletal disorders. However, the process of building digital human models and capturing their behaviors requires many costly and time-consuming fabrication iterations. To overcome the limitations of this expensive and time-consuming process, many studies have recently presented a markerless motion capture approach that reconstructs the time-varying skeletal motions from optical devices. However, the drawback of the markerless motion capture approach is that the phenomenon of occlusion of motion data occurs in real-time human simulation. In this study, we propose a systematic method of discriminating missing or inaccurate motion data due to motion occlusion and interpolating a sequence of motion frames captured by a markerless depth camera.

• Korean Journal of Applied Biomechanics
• /
• v.17 no.3
• /
• pp.69-80
• /
• 2007

The purpose of this study was to investigate the difference of ground reaction forces of swimming athletes during their starting motion and to find out the most effective starting motions which were used in swimming athletes. The subjects were 9 male and 8 female high school swimming athletes who were athletic career over 7 years and used three starting motions in competition. The ground reaction forces were measured from each athletes performing three starting motion each of the open grap starting motion, closed grap starting motion and track starting motion. For the measurement, the force platform of AMTI company was utilized, and the analysis on measured ground reaction forces were used of Biosoft(Ver. 1.0). The items measured were stance time, Fz max deceleration force and Fz max deceleration force time, Fz mid stance force and Fz mid stance force time, Fz max acceleration force and Fz max acceleration force time, Torque maximum and Torque maximum time, Torque average, Excursion along Y axis of center of pressure of foot, Excursion along X axis of center of pressure of foot, Length of center of pressure of foot, Average velocity of center of pressure of foot. The data measured by the closed grap starting motion, open grap starting motion and track starting motion were analyzed by one-way repeated ANOVA. The results were as follows ; 1. The Fz max deceleration force time, Fz mid stance force, Fz max acceleration force, Torque maximum and Torque maximum time, Excursion along Y axis of center of pressure of foot, Average velocity of center of pressure of foot were significantly fast and large in the closed grap starting motion then open grap starting motion and track starting motion. 2. The Excursion along Y axis of center of pressure of foot was significantly long in the closed grap starting motion then open grap starting motion and track starting motion.

• Journal of the Ergonomics Society of Korea
• /
• v.32 no.3
• /
• pp.217-227
• /
• 2013

Objective: The purpose of this study was to analyze 'response time', 'peak response time' and 'overshoot value' for each muscle by applying the EMG signal to the vehicle response in ISO 7401 and to quantify the response of the driver according to vehicle characteristics by comparing vehicle characteristics and muscle responses of the driver. Background: The Open-loop test defined in international standards ISO 7401 is the only method for evaluating the performance of the vehicle. However, this test was focused only on mechanical responses, not driver's ones. Method: One skilled male driver(22 yrs. experience) was participated in this experiment to measure muscle activities of the driver in transient state. Then the seven muscle signals were applied to calculate 'response time', 'peak response time', and 'overshoot value'. Results: In the analyses of the EMG data, the effects of vehicle type and muscle were statistically significant on the 'response time' and 'peak response time'. Also, the effects of vehicle type, muscle, and lateral acceleration level were statistically significant on the 'overshoot value' in this study. According to the analyses of the vehicle motion data, vehicle motion variable(LatAcc, Roll, YawVel) was statistically significant on the 'response time' and vehicle type, vehicle motion variable, and lateral acceleration level were statistically significant on the 'peak response time', respectively. Conclusion: In the analyses of the 'response time' and 'overshoot value', the data of muscle activities(EMGs) was better index that could evaluate the vehicle characteristic and performance than the data of vehicle motion. In case of peak response time, both EMG and vehicle motion data were good index. Application: The EMGs data from a driver might be applicable as index for evaluation of various vehicle performances based on this study.

• Journal of radiological science and technology
• /
• v.16 no.2
• /
• pp.19-26
• /
• 1993

Magnetic Resonance Image represents three-dimensional diagnostic imaging technique using both nuclear magnetic resonance phenomenon and computer. Compared with computed tomography (CT), MRI have advantages harmless to patient's body, three-dimensional image with high resolution and disadvantages long data acquisition time because of long T1 relaxation time, relatively low signal to noise ratio, high cost of setting, also. As physiologic motion of tissue results in motion ghost in MRI, high 2.0Tesla make improve low signal to noise ratio. This study have aim to improve image quality with controling motion ghost of tissue. Supposing a moving pixel in constant frequency, one pixel make two ghosts which are same size and different anti-phase. So, this study will show adjust parameter on locational control of motion ghost. Author made moving phantom replaced by respiratory movement of human, researched change of motion frequency, FOV by location shift, and them decided optimal FOV (field of view). The results are as follows: 1. The frequency content of the motion determines how far the image always appear in phase-encoding direction, the morphology of the ghost image is characteristic of the direction of the motion and its amplitude. 2. Double FOV of fixed signal object for locational control of motion ghost is recommended. Decreasement of spatial resolution by increasing FOV can compensate on increasing of matrix in spite of scan time increasement.

• Journal of the Korean Society for Precision Engineering
• /
• v.18 no.7
• /
• pp.53-64
• /
• 2001

The gain-scheduling control technique is vary useful in the control problem incorporating time varying parameters which can be measured in real time. Based on these facts, in this paper the sway control problem of the pendulum motion of a container hanging on the trolly, which transports containers from a container ship to trucks, is considered. In the container crane control problem, suppressing the residual swing motion of the container at the end of acceleration, deceleration or the case of that the unexpected disturbance input exists is main issue. For this problem, in general, the trolley motion control strategy is introduced and applied. But, in this paper, we introduce and synthesize a new type of swing motion control system. In this control system, a small auxiliary mass is installed on the spreader. And the actuator reacts against the auxiliary mass, applying inertial control forces to the container to reduce the swing motion in the desired manner. In this paper, we assume that an plant parameter is varying and apply the gain-scheduling control technique design the anti-swing motion control system for the controlled plant. In this control system, the controller dynamics are adjusted in real-time according to time-varying plant parameters. And the simulation result shows that the proposed control strategy is shown to be useful to the case of time-varying system and, robust to disturbances like winds and initial sway motion.

• Journal of the Ergonomics Society of Korea
• /
• v.9 no.2
• /
• pp.21-28
• /
• 1990

The robot motion control in the industrial robot is generally executed by the teach pendant. But, it requires much teaching time and workload to the operators. This study suggests the use of the robot motion control method by the computed keyboard in the industrial robot instead of the teach pendant. TES/CCS(Teaching Expert System/Cartesian Coordinate System) and TES/WCS(Teaching Expert System/World Coordinate System) that have been proposed to improve the robot motion control are applied for this concept. This study is intended to improve the robot motion control in TES/CCS. Parameter limitation problems in getting the motion data on position and posture of the robot in macro motion control are solved by proposed geometric algorithm. This result demonstrates reduction of the average teaching task time to the teaching position.