• Journal of Korean Medicine Rehabilitation
• /
• v.18 no.1
• /
• pp.163-172
• /
• 2008

Objectives : This study was performed to evaluate the effects of thoracic vertebral region's Du mai(督脈) and Jia ji xue(夾脊穴) intervention on active range of motion(ROM) restricted shoulder pain. Methods : 1. Measurement : The unpleasantness of pain was measured by visual analogue scale(VAS), and ROM was measured by using Goniometer and scratch test. 2. Intervention : Use Acupuncture and bee venom injection in thoracic vertebral region's Du mai(督脈) and Jia ji xue(夾脊穴) that display main tender points. Results : The pain and ROM were improved after thoracic vertebral region intervention. Conclusion : Thoracic vertebral region intervention was effective to active ROM restricted shoulder pain, to reduce the pain and to improve ROM. And this study shows that active ROM restricted shoulder pain and thoracic vertebral region's tender points are connected to each other. Also, region that suggest main tender points previews region of thoracic vertebrae 5-8.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.30 no.4
• /
• pp.92-98
• /
• 2002

In this study, maximum launch range and F-pole are evaluated and analyzed for the semi-active radar missile concerning various launch condition, performance limitation and target maneuvers. Furthermore, general evasion maneuvers are considered when shooter approaches to target with head-on conditions. A point-mass target, shooter and missile model is used including aircraft and missile dynamics. More realistic missile motion simulation is conducted using aerodynamic performance data, geometry, performance limitation, radar seeker performance and so on. Maximum launch range, which is the distance for intercept satisfying target and missile motion and performance, is evaluated using root finding method. F-pole, which is the distance between target and shooter when intercept is completed, is evaluated assuming that shooter maneuvers through pursuit guidance to target.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2007.11a
• /
• pp.565-573
• /
• 2007

This paper is concerned with the dynamic modeling, active vibration controller design and experiments for a cylindrical shell equipped with MFC actuators. The dynamic model was derived by using Rayleigh-Ritz method based on Donnel-Mushtari shell theory. The actuator and sensors for the MFC actuator equations were derived based on pin-force model. The equations of motion were then reduced to modal equations of motion by considering the modes of interest. The sensor equations were also converted to a reduced form. An aluminum shell was fabricated to demonstrate the effectiveness of modeling and control techniques. The boundary conditions at both ends of the shell were assumed to be shear diaphragm. Theoretical natural frequencies were calculated and compared to experimental result. It was observed that the theoretical result is in good agreement with experimental result for the first two modes. The multi-input and multi-output positive position feedback controller, which can cope with first two modes, was then designed based on the blockinverse theory and implemented using DSP. It was found from experiment that vibrations can be successfully suppressed.

• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.4 no.4
• /
• pp.39-47
• /
• 2005

In this paper, a novel high power micropump using active check valves in place of conventional passive check valves employed at the inlet and outlet ports is presented. It actively controls open/close motion of check valves using piezoelectric actuator for expansion/contraction of pump chamber. A prototype micropump having an effective size of $17mm{\times}8mm{\times}11mm$ is fabricated. Frequency-dependent flow rate characteristics, bi-directional flow characteristics and load characteristics are experimentally investigated using a timing control method for valve closing motion. From the obtained experimental results, it is ascertained that optimal values of the phase shift compared to the voltage to drive pump chamber are $15^{\circ}$ for inlet check valve and $195^{\circ}$ for outlet. Based on the obtained results, a sheet-type active shuttle valve that has a unified valve-body for inlet and outlet check valves is proposed. A micropump with an effective size of $10mm{\times}10mm{\times}10mm$ is fabricated and the basic characteristics are experimentally investigated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
• /
• 2009.04a
• /
• pp.444-449
• /
• 2009

An engine is one of the most dominant noise and vibration sources in vehicle systems. Therefore, in order to resolve noise and vibration problems due to engine, various types of engine mounts have been proposed. This work presents a new type of active engine mount system featuring a magneto-rheological (MR) fluid and a piezostack actuator. As a first step, six degrees-of freedom dynamic model of an in-line four-cylinder engine which has three points mounting system is derived by considering the dynamic behaviors of MR mount and piezostack mount. In the configuration of engine mount system, two MR mounts are installed for vibration control of roll mode motion whose energy is very high in low frequency range, while one piezostack mount is installed for vibration control of bounce and pitch mode motion whose energy is relatively high in high frequency range. As a second step, linear quadratic regulator (LQR) controller is synthesized to actively control the imposed vibration. In order to demonstrate the effectiveness of the proposed active engine mount, vibration control performances are evaluated under various engine operating speeds (wide frequency range) and presented in time domain.

• Journal of Institute of Control, Robotics and Systems
• /
• v.2 no.3
• /
• pp.181-187
• /
• 1996

A frictionless positioning device using cone-shaped active magnetic bearings(AMBs) is developed, which is driven by a brushless DC motor equipped with resolver. The cone-shaped AMB feature that the structure is simple and yet the five d.o.f. rotor motion is controlled by four magnet pairs. A linearized dynamic model, which accounts for the relationship between input voltage and output current in the cone-shaped magnet, is developed and the azimuth motion of the frictionless positioning device is modeled as the second order system. The feedback controller is designed by using linear quadratic regulator with integral action optimal control law so that the cone-shaped AMB system is stabilized and the frictionless positioning device gets the zero steady state. It is observed that the linearized dynamic model is adequate and the frictionless positioning device can achieve the tracking accuracy within the sensor resolution.

• Journal of the Korean Society of Physical Medicine
• /
• v.6 no.1
• /
• pp.103-108
• /
• 2011

Purpose : The purposes of this study were to compare the muscle activity ratio of tibialis anterior (TA) / extensor digitorum longus (EDL) during the active ankle dorsiflexion in subjects with the normal toe (NT) and the hammer toe (HT). Methods : Nineteen subjects with the NT group and nineteen subjects with the HT group were recruited for this study. The muscle activities of TA and EDL were measured by using surface electromyography (EMG) and the angles of ankle dorsiflexion and eversion of the subtalar joint were measured by using 3-dementional motion analysis during the active ankle dorsiflexion in prone position. Results : The muscle activity ratio of TA / EDL was significantly lower in the HT group compared to the NT group (p<.05). The angle of ankle dorsiflexion was significantly lower in the HT group compared to the NT group (p<.05). Conclusions : These results suggest that muscle imbalance between TA and EDL muscle and decreased ankle dorsiflexion range of motion may contribute to hammer toe deformity. Further studies are needed to confirm that the correcting of this imbalance and the increasing ankle dorsiflexion could improve toe alignment in the subjects with HT.

• Proceedings of the KSME Conference
• /
• 2003.11a
• /
• pp.1864-1869
• /
• 2003

A novel piezoelectric micropump using active check valves in place of conventional passive check valves in inlet and outlet has been proposed and investigated. It actively controls open/close motion of check valves using piezoelectric actuator for expansion/contraction of pump chamber. In this paper, bi-directional flow characteristics and load characteristics are experimentally investigated using an adequate timing control for valve closing motion with a prototype micropump fabricated with the effective size of $17{\times}8{\times}11mm^{3}$. From the experimental results, it is ascertained that optimal values of phase shift against voltage to drive pump chamber for realization of a miniaturized but powerful micropump, are $15^{\circ}$ in inlet check valve and $195^{\circ}$ in outlet. Based on the obtained results, a sheet-type active shuttle valve that has a unified valve-body for inlet and outlet check valves is proposed. A micropump with the effective size of $10{\times}10{\times}10mm^{3}$ is fabricated and basic characteristics are experimentally investigated.

• Transactions of the Korean Society for Noise and Vibration Engineering
• /
• v.19 no.6
• /
• pp.583-590
• /
• 2009

An engine is one of the most dominant noise and vibration sources in vehicle systems. Therefore, in order to resolve noise and vibration problems due to engine, various types of engine mounts have been proposed. This work presents a new type of active engine mount system featuring a magneto-rheological (MR) fluid and a piezostack actuator. As a first step, six degrees-of freedom dynamic model of an in-line four-cylinder engine which has three points mounting system is derived by considering the dynamic behaviors of MR mount and piezostack mount. In the configuration of engine mount system, two MR mounts are installed for vibration control of roll mode motion whose energy is very high in low frequency range, while one piezostack mount is installed for vibration control of bounce and pitch mode motion whose energy is relatively high in high frequency range. As a second step, linear quadratic regulator (LQR) controller is synthesized to actively control the imposed vibration. In order to demonstrate the effectiveness of the proposed active engine mount, vibration control performances are evaluated under various engine operating speeds(wide frequency range) and presented in time domain.

• Proceedings of the KSME Conference
• /
• 2001.06b
• /
• pp.164-169
• /
• 2001

The active magnetic bearing has many advantages - an active positioning, no contact and lubrication free motion - and is widely used in high precision motion stages. But, the conventional magnetic bearings composed of electromagnets only are power consuming due to their bias current and have the excessive heat generation, which can make the repeatability of the positioning system worse. To overcome this drawback, we developed a novel permanent magnet (PM) biased linear magnetic bearing for a high precision magnetically levitated stage. The permanent magnets provide a bias flux and generate a bias force, and the electromagnet increases or reduces a flux of the permanent magnets and gives a levitation force. This paper presents a theoretical magnetic circuit analysis, FEM analysis and experimental data from the 1-DOF tests, and compares the theoretical power consumption of the electromagnetic bearings and the PM biased linear magnetic bearings. The PM biased linear magnetic bearing presented in this paper gives better load capacity but lower power consumption than a conventional electromagnetic bearing and will be adopted in our 6-DOF high precision linear positioning maglev stage.