• 대한의용생체공학회:의공학회지
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• 제38권2호
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• pp.57-61
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• 2017

The purpose of this study was to investigate the effect of direction (pitch and roll) on the perception of support surface rotation while standing. Thirty young healthy subjects participated in this study. Support surface was rotated at an unexpected instant in a very slow speed (0.2 deg/s). The direction of support surface rotation was randomly chosen among pitch (forward and backward) and roll (right and left) directions. The experiment was performed with eyes open and closed. Perception performance was evaluated by the perception threshold, defined as the rotation angle of the surface at the instant when a subject recognized that the support surface was moving. Results showed that the perception threshold was smaller for roll directions than pitch directions irrespective of vision and gender (p < 0.01). This indicates that the perception of support surface rotation is more sensitive in roll direction than in pitch direction. Among three sensory functions related to postural perception, the effect of vestibular and visual functions on the direction difference of the perception should be little because of the very slow surface rotation and independence on visual conditions. Therefore, the direction dependence of perception would have been affected mainly by the somatosensory function.

• 한국전문물리치료학회지
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• 제26권1호
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• pp.67-74
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• 2019

Background: Uncontrolled lumbopelvic movement leads to asymmetric symptoms and causes pain in the lumbar and pelvic regions. So many patients have uncontrolled lumbopelvic movement. Passive support devices are used for unstable lumbopelvic patient. So, we need to understand that influence of passive support on lumbopelvic stability. It is important to examine that using the pelvic belt on abdominal muscle activity, pelvic rotation and pelvic tilt. Objects: This study observed abdominal muscle activity, pelvic rotation and tilt angles were compared during active straight leg raise (ASLR) with and without pelvic compression belt. Methods: Sixteen healthy women were participated in this study. ASRL with and without pelvic compression belt was performed for 5 sec, until their leg touched the target bar that was set 20 cm above the base. Surface electromyography was recorded from rectus abdominis (RA), internal oblique abdominis (IO), and external oblique abdominis (EO) bilaterally. And pelvic rotation and tilt angles were measured by motion capture system. Results: There were significantly less activities of left EO (p=.042), right EO (p=.031), left IO (p=.039), right IO (p=.019), left RA (p=.044), and right RA (p=.042) and a greater right pelvic rotation angle (p=.008) and anterior pelvic tilt angle (p<.001) during ASLR with pelvic compression belt. Conclusion: These results showed that abdominal activity was reduced while the right pelvic rotation angle and anterior pelvic tilt angle were increased during ASLR with a pelvic compression belt. In other words, although pelvic compression belt could support abdominal muscle activity, it would be difficult to control pelvic movement. So pelvic belt would not be useful for controlled ASLR.

• Steel and Composite Structures
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• 제41권6호
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• pp.831-850
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• 2021

Surface subsidence caused by mining subsidence has an impact on neighboring structures and utilities. In other words, subsurface voids created by mining or tunneling activities induce soil movement, exposing buildings to physical and/or functional destruction. Soil-structure is evaluated employing probability distribution laws to account for their uncertainty and complexity to estimate structural vulnerability. In this study, to investigate the displacement field and surface settlement profile caused by mining subsidence, on the basis of a Winklersoil model, analytical equations for the moment-rotation response ofsoil during mining induced ground movements are developed. To define the full static moment-rotation response, an equation for the uplift-yield state is constructed and integrated with equations for the uplift- and yield-only conditions. The constructed model's findings reveal that the inverse of the factor of safety (x) has a considerable influence on the moment-rotation curve. The maximal moment-rotation response of the footing is defined by X = 0:6. Despite the use of Winkler model, the computed moment-rotation response results derived from the literature were analyzed through the ELM-SVM hybrid of Extreme Learning Machine (ELM) and Support Vector Machine (SVM). Also, Monte Carlo simulations are used to apply continuous random parameters to assess the transmission of ground motions to structures. Following the findings of RMSE and R2, the results show that the choice of probabilistic laws of input parameters has a substantial impact on the outcome of analysis performed.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1996년도 Proceedings of the Korea Automatic Control Conference, 11th (KACC); Pohang, Korea; 24-26 Oct. 1996
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• pp.393-396
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• 1996

This paper studies electrostatically suspended induction motors (ESIM). The ESIM possesses the rotating ability of an ordinary electrostatic induction motor, in addition to providing contactless support by electrostatic suspension. To accomplish these two functions, a feedback control strategy and the operating principle of an ordinary electrostatic induction motor are used. The stator possesses electrodes which exert the electrostatic forces to the rotor and are divided into a part responsible for suspension and one for rotation. Two rotor types are utilized: a polished glass disk without any surface treatment, and a polished glass disk covered with a thin layer of conductive material (ITO layer) on only one side. In this paper, the principle of the ESIM is described, followed by stator electrode design, experimental apparatus, control strategy for stable suspension. Experimental results show that the glass disk has been rotated with a speed of approximately 70 rpm while being suspended stably at a gap length of 0.3 mm.

• The Journal of Korean Physical Therapy
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• 제32권3호
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• pp.157-162
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• 2020

Purpose: This study was to evaluate several tasks performed at a high intensity in terms of their ability to elicit EMG activity in the serratus anterior by comparing the EMG activities of the serratus anterior, upper trapezius, and lower trapezius muscles during six tasks combined shoulder flexion with rotation. Methods: Fifteen healthy males were recruited to this study. Each subject was instructed to assume a sitting position without back support and asked to flex (90° or 120°) the right shoulder and protract the scapula in the sagittal plane with maximal external rotation; to assume a neutral position; or to internally rotate the glenohumeral joint. The EMG data were collected from the serratus anterior (SA), upper trapezius (UT), and lower trapezius (LT) muscles were normalized to maximum voluntary isometric contraction. The UT/LT and UT/SA muscle activity ratios in each task were assessed by calculating the surface EMG. Data were analyzed by two-way repeated-measures analysis of variance, with the level of significance set at p<0.05. Results: The results of this study, shoulder flexion with external rotation resulted in low upper trapezius/serratus anterior and upper trapezius/lower trapezius ratios and a relatively high level of serratus anterior activation. Conclusion: Shoulder flexion with external rotation used herein may be considered as important for clinical interventions aimed at selectively increasing SA strengthen and clinical selection of exercises for improving glenohumeral joint and scapulothoracic control.

• 대한정형도수물리치료학회지
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• 제11권2호
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• pp.71-82
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• 2005

The couple force of the scapular stabilizers for upward rotation that include the upper and lower trapezius, serratus anterior muscles is essential to maintain the stability of shoulder joint. But if there is an imbalance of these muscles, it would occur many problems of shoulder joint. A push-up plus exercise with an unstable support is used in order to increase the muscle activity and stimulate the proprioception of shoulder joint. The purpose of this study was to compare the muscle activity of upper and lower trapezius, serratus anterior muscles and to determine which exercise is more effective when subjects perform push-up plus exercise in the stable support and unstable support. 15 healthy subjects and 15 painful subjects with injury of shoulder joint participated in this study. Surface electromyography data were collected during plus phase of push-up plus exercise. The types of push-up plus exercise were composed of three conditions. Stable type is subjects performed the push-up plus exercise on the fixed support and unstable type 1 is on the sling without shaking and unstable type 2 is on the sling with shaking by tester's manual. The upper and lower trapezius activities of injured group were higher than uninjured group at three measure conditions, but serratus anterior activities were not. The UT/SA ratio of injured group was higher than uninjured group at three measure conditions. The serratus anterior activities were most high at unstable 2 measure in both groups. The UT/SA ratio was most low at unstable 2 measure condition in injured group only. The present result revealed that push-up plus exercise in the unstable support with shaking which took most high serratus anterior activities and most low of UT/SA ratio is optimal cure method that can improve the imbalance of the scapular stabilizer.

• Applied Microscopy
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• 제45권4호
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• pp.214-217
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• 2015

This study introduces metal coating as an effective sample preparation method to remove charge-up caused by the shadow effect during field emission scanning electron microscope (FE-SEM) analysis of dynamic structured samples. During a FE-SEM analysis, charge-up occurs when the primary electrons (input electrons) that scan the specimens are not equal to the output electrons (secondary electrons, backscattered electrons, auger electrons, etc.) generated from the specimens. To remove charge-up, a metal layer of Pt, Au or Pd is applied on the surface of the sample. However, in some cases, charge-up still occurs due to the shadow effect. This study developed a coating method that effectively removes charge-up. By creating a converted sample stage capable of simultaneous tilt and rotation, the shadow effect was successfully removed, and image data without charge-up were obtained.

• 제어로봇시스템학회논문지
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• 제10권11호
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• pp.1044-1051
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• 2004

This paper described a novel locomotion interface that can generate infinite floor for various surface, named as virtual walking machine. This interface allows users to participate in a life-like walking experience in virtual environments, which include various terrains such as plains, slopes and stair ground surfaces. The interface is composed of two three-DOF (X, Y, Yaw) planar devices and two four-DOF (Pitch, Roll, Z, and relative rotation) footpads. The planar devices are driven by AC servomotors for generating fast motions, while the footpad devices are driven by pneumatic actuators for continuous support of human weight. To simulate natural human walking, the locomotion interface design specification are acquired based on gait analysis and each mechanism is optimally designed and manufactured to satisfy the given requirements. The designed locomotion interface allows natural walking(step: 0.8m, height: 20cm, load capability: 100kg, slope:30deg) for various terrains.

• 천문학회보
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• 제44권2호
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• pp.68.4-68.4
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• 2019

In this poster, we present a relation between the Galactic foregrounds and Galactic latitude to study the structure of the Galactic foregrounds. We propose that the standard deviation of observed values along a line of sight with Galactic latitude b ('σ_l.o.s') is inversely proportional to ${\sqrt{sin{\mid}b{\mid}}}$. To confirm this, we use synchrotron intensity data from the Planck archive and rotation measure (RM) data from the NVSS. We divided the sphere of the Galactic coordinate into bins with a constant surface area and calculated the average of standard deviation along Galactic latitude ('σ_lat'). We compared σ_lat ${\sqrt{sin{\mid}b{\mid}}}$ with σ_lat along Galactic latitude and found that σ_lat ${\sqrt{sin{\mid}b{\mid}}}$ is the most constant. These results support that the relation is reasonable.

• 한국전문물리치료학회지
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• 제9권2호
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• pp.1-17
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• 2002

The purpose of this study was to identify the differences of the static and the dynamic balance reactions in the flexion syndrome (FS) and the extension syndrome (ES) group of the patients with chronic lowback pain (LBP) and healthy subjects. Twenty subjects were included in each group. By using EquiTest 5.02, the static balance was measured by the equilibrium score and the strategy score of sensory organization test (SOT), while the dynamic balance was measured by the latency of motor control test (MCT) and the sway energy of adaptation test (ADT). Oswestry Disability Index (OSI) was used to measure level of the disability in patients with chronic LBP. The equilibrium scores, the strategies of SOT, and thelatencies of MCT of three groups were compared with one way ANOVA, while the sway energy of ADT was compared with repeated measures one way ANOVA. The results of this study showed that the equilibrium scores and the strategy scores of SOT were significantly lower in patients with chronic LBP than in healthy subjects. The equilibrium scores and the strategy scores of SOT were significantly differences between the FS and ES groups in condition 5 (support surface was sway-referenced and visual information waseliminated by eye closure), and 6 (support surface was sway-referenced and visual information was altered by sway-referencing). The FS group showed delayed average reaction time at large posterior translation, however, the ES group showed delayed average reaction time at large anterior translation, Even though the sway energy of the patients with chronic LBP were greater than that of healthy subjects during the toe down (plantar flexion rotation), the values between the FS and ES groups didn't show any significant difference. The disability level showed highly correlation with the equilibrium score of the condition 5. As the results, the FS and ES groups divided by the their symptoms and signs in patients with chronic LBP showed different balance reaction. Therefore, more accurate evaluation and balance treatments are needed to focus on their symptoms and signs in patients with chronic LBP.