• Journal of the Korean Society for Precision Engineering
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• v.17 no.11
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• pp.81-87
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• 2000

A new resonator that is fabricated by single polysilicon layer process is presented. The resonator can move in two orthogonal direction on the plane parallel to the substrate. And the resonant frequencies of the two modes are intrinsically designed to be identical since the overall structure of the resonator is symmetric about the two directions of motion. Since the resonator ideally has two identical vibration mode, it can be applied to various micro-devices that requires multi DOF motion, especially to microgyroscopes. To investigate the feasibility of application of the resonator, dynamic model of the resonator including the nonlinear behavior of driving electrodes is derived and evaluated with the fabricated one, and the self-tuning characteristics are proved though experiments.

• International Journal of Internet, Broadcasting and Communication
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• v.10 no.4
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• pp.43-49
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• 2018

Modern people communicate in a digital space without being limited by physical space and time. On the internet, people's desire for self-expression is getting bigger, and the most common self-expression tool is characters. Characters are visual materials to express human thoughts and desires. This study is a method to positively express the viewer's self in an interactive Hangeul system. The proposed system produces new formative shapes and meanings of Hangeul through the process of deconstructing and reconstructing the characters. Immediate character transformations that are synchronized with the motion of the viewer act as a tool of self-expression by inducing the viewer's active interaction repeatedly. Therefore, the proposed interactive Hangeul is more than enough to be used as a new graphic tool beyond the text to be read, and it is highly likely to develop into cultural contents using it.

• Journal of Institute of Convergence Technology
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• v.6 no.2
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• pp.9-13
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• 2016

Robot usually requires spline motion to move through multiple knots. In this paper, catmull-rom spline method is applied to the trajectory planning of industrial robot in task space. Centripetal catmull-rom is selected to avoid self-intersection and slow motion which can be occurred in uniform and chordal spline. The method to set two control points are proposed to satisfy velocity conditions of initial and final knots. To optimize robot motion, time scaling method is presented to minimize margin between real robot value and maximum value in velocity and acceleration. The simulation results show that the proposed methods are applied to trajectory planning and robot can follow the planned trajectory while robot motion does not exceed maximum value of velocity and acceleration.

• Structural Engineering and Mechanics
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• v.29 no.4
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• pp.433-453
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• 2008

The equation of motion of a one way (vertical) spanning strip wall, as an assembly of two rigid bodies, is presented. Only one degree of freedom is needed to completely describe the wall response as the bodies are assumed to be perfectly rectangular and are allowed to rock but not to slide horizontally. Furthermore, no arching action occurs since vertical motion of the upper body is not restrained. Consequently, the equation of motion is nonlinear, with non constant coefficients and a Coriolis acceleration term. Phenomena associated with overburden to self weight ratio, motion triggering, impulsive energy dissipation, amplitude dependency of damping and period of vibration, and scale effect are discussed, contributing to a more complete understanding of experimental observations and to an estimation of system parameters based on the wall characteristics, such as intermediate hinge height and energy damping, necessary to perform nonlinear time history analyses. A comparison to a simple standing, or parapet, wall is developed in order to better highlight the characteristics of this assembly.

• The Journal of Korea Robotics Society
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• v.17 no.3
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• pp.359-364
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• 2022

This study presents a nonlinear model predictive control (NMPC)-based obstacle avoidance and whole-body motion planning method for the mobile manipulators. For the whole-body motion control, the mobile manipulator with an omnidirectional mobile base was modeled as a nine degrees-of-freedom (DoFs) serial open chain with the PPR (base) plus 6R (arm) joints, and a swept sphere volume (SSV) was applied to define a convex hull for collision avoidance. The proposed receding horizon control scheme can generate a trajectory to track the end-effector pose while avoiding the self-collision and obstacle in the task space. The proposed method could be calculated using an interior-point (IP) method solver with 100[ms] sampling time and ten samples of horizon size, and the validation of the method was conducted in the environment of Pybullet simulation.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.9
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• pp.942-949
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• 2014

In this paper, a new steering system for a self-balancing electric scooter is proposed with an intuitive steering command input method, where the steering command is generated from the rider's motion of shifting body to move the center of gravity toward the rotational direction. For the purpose, weight distributions on the rider's feet are measured using force sensors placed beneath the rider's feet, and the difference is applied to a steering control system. Stability of the steering system and resultant radius of gyration is investigated by modeling the steering system in consideration of the rider's motion and centrifugal force. The proposed steering system is applied to experiments, and the results are presented to prove the validity of the proposed method.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.30 no.6
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• pp.1033-1043
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• 1997

In order to understand the generation mechanism of the Ulleung Eddy, we carried out a series of numerical experiments using the nonlinear 11/2 - layer model allowing the inflow of the Tsushima Current. According to our numerical results, the Ulleung Eddy was generated due to the inflow variations of the Tsushima Current. Its inflow through the Korea Strait was deflected to the east due to the Coriolis force and the nonlinear self advection. Thus, an anticyclonic motion was formed at the north of the Korea Strait. The inflow became a coastal boundary current, and finally flowed out model ocean through the eastern exit. When the speed of inflow decreased slowly, the eddy- like motion at the north of the Korea Strait changed into an enclosed anticyclonic eddy of about 200 km in diameter. The Ulleung Eddy became circular shape due to the nonlinear self advection, then changed into elliptical shape in meridional direction because of the blocking effect of the western boundary.

• The Journal of Korean Physical Therapy
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• v.30 no.1
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• pp.23-28
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• 2018

Purpose: This study examined the effectiveness of iliopsoas self-stretching on the hip extension angle, gluteus maximus (GM) activity, and pelvic compensated angle during prone hip extension (PHE) in subjects with iliopsoas shortness. Methods: Twenty-healthy subjects with iliopsoas shortness were recruited. Electromyography (EMG) was used to examine erector spinae (ES), multifidus (MF), GM, and biceps femoris (BF) while performing PHE. An electromagnetic tracking motion analysis device was used to measure the pelvic compensations. The pelvic compensations while performing PHE were considered to be anterior tilting and rotation. A modified Thomas test was used to monitor the hip extension angle before and after iliopsoas self-stretching. A paired t-test was used to investigate the significant difference after iliopsoas self-stretching during PHE. The level of statistical significance was set to ${\alpha}=0.05$. Results: Muscle activity of GM and hip extension angle were significantly greater after iliopsoas self-stretching compared to that before iliopsoas self-stretching during PHE (p<0.05). BF and pelvic rotation angle were significantly lower after iliopsoas self-stretching compared to that before iliopsoas self-stretching during PHE (p<0.05). The muscle activity of ES was not significantly different between PHE before and after iliopsoas self-stretching (p>0.05). Conclusion: Iliopsoas self-stretching can be effective in selectively strengthening the GM muscles with minimized pelvic compensation in subjects with iliopsoas shortness.

• Journal of the Korea Convergence Society
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• v.9 no.4
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• pp.409-421
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• 2018

The purpose of this study was to examine the effects of shoulder rehabilitation exercise convergence program. This study used a nonequivalent control group pretest-posttest design. A sample of 58 patients undergoing shoulder surgery, was included. The experimental group was given shoulder rehabilitation exercise convergence program including audiovisual education, shoulder rehabilitation exercise and exercise monitoring. The data were collected using a structured questionnaire and measured range of motion(ROM) of shoulder joint and were analyzed using descriptive statistics, ${\chi}^2-test$, t-test and ANCOVA. The experimental group reported significantly lower shoulder pain than control group(p<.001). Shoulder joint ROM and exercise self-efficacy were significantly higher in the experimental group than in the control group(p=.038; p<.001). This findings indicate that shoulder rehabilitation exercise convergence program can be an effective intervention for shoulder surgery patients. Continued development of convergence interventions for patients undergoing various conditions in practice, is suggested.

• Structural Engineering and Mechanics
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• v.62 no.4
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• pp.497-506
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• 2017

A low damage self-centering braced frame equipped with post-tensioning strands is capable of directing damage to replaceable butterfly-shaped fuses. This paper investigates the seismic performance of rocking braced frame under near-field pulse-like ground motions compared to far-field records. A non-linear time history analysis is performed for twelve self-centering archetypes. A sensitivity analysis is carried out to examine the influences of ground motion types and modeling parameters. Findings represent the proper efficiency of the self-centering system under both far-field and near-field pulse-like ground motions.