• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.78.1-78
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• 2002

A quantitative performance evaluation of an intuitive robot teach method is presented. $\textbullet$ Teach times for two types of teach tasks are compared to the conventional teach pendant method. $\textbullet$ Teach tasks requiring a 4 DOF motion and a 6 DOF motion were tested. $\textbullet$ Compared to the teach pendant method, the proposed method reduce the teach times to 75% and 55%. $\textbullet$ The intuitive teach method is easier for the untrained robot users.

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.51.4-51
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• 2002

$\textbullet$ A noval haptic mouse system is developed for human computer interface. $\textbullet$ Five bar mechanism is adapted for 2 dof force feedback with virtual environment. $\textbullet$ Double prismatic joint type mechanism is adapted to reflect 1 dof grabbing force feedback. $\textbullet$ Cable driven mechansim is used for actuation to reduce backlash and endow backdrivability. $\textbullet$ Virtual wall perception experiment is conducted to obtain force specification for haptic mouse. $\textbullet$ Average mouse workspace is measured using magnetic position tracker.

• Journal of the Korean Society of Industry Convergence
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• v.19 no.4
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• pp.206-215
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• 2016

Delta parallel robots are now widely used for high-speed applications. However, typical Delta robots, such as ABB Flexpicker suffer from rotating axis with passive prismatic joint subjected to critical speed and so requiring careful maintenance. In this paper, a novel 4-DOF high-speed parallel robot with four legs is presented, which consists of three legs with 90 degree arrangement for translational motions and one remaining leg with rack & pinion gears for rotational motion. The inverse kinematics, velocity, acceleration, statics, and inverse dynamics have been analyzed. From the workspace analysis and inverse dynamics simulation for 0.43 sec cycle time, the 4-axis parallel robot prototype with 12kg payload has been designed. In the future research, computed torque control methods will be developed for the prototype.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.4_2
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• pp.655-662
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• 2022

Recently, with the increase in the use of UAV(unmanned aerial vehicles), research on horizontal maintenance stations that can take off and land in various environments has been actively conducted. These stations can safely land UAV through multiple DOF(degrees of freedom) or at least 2-DOF-based actuator actuation. Among them, many researchers are dealing with the multi-DOF stewart platform due to its high safety. However, the stewart platform requires high-precision control technology because it requires a lot of torque to actuate according to the load action. Therefore, in this paper, to solve the mentioned problem, a bevel gear-based 2-DOF horizontal maintenance station system is proposed. The proposed system is configured to prevent damage due to air resistance when maintaining ships and to install it in a small space. Also, in terms of system configuration, the bevel gear-based horizontal maintenance system has the main advantage of being able to take off and land UAVs of various sizes through the replacement of station pads. The driving of the system consists of a simple form that can control the motor by adjusting the rotation speed of the motor according to the sea waveform.

• The Journal of Korea Robotics Society
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• v.3 no.4
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• pp.315-322
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• 2008

A new soft finger mechanism using a spring as a backbone is proposed in this work. It is a 4 DOF mechanism that consists of a spring and 3 cylinders, which behave like joints with 3 up-and-down rotations and 1 left-and-right rotation. To control each joint, cylinders have small holes in their cross-sectional areas, and wires of different length are penetrated into these holes. We can control each joint by pulling the corresponding wire. The forward kinematics is solved by using the geometry of mechanism. And the relationship (Jacobian) between the linear velocity of the wires and the joint angular rate is obtained. A virtual simulator is developed to test the validity of the kinematic model. In the experiment, first, the position control is conducted by tracking a given trajectory. Second, to verify the flexibility and safety, we show that the soft finger deflects in a safe manner, in spite of the collision with environment.

• Interaction and multiscale mechanics
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• v.4 no.4
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• pp.273-289
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• 2011

The vibration response of the bridges under the moving vehicular load is of importance for engineers to estimate the serviceability of existing bridges and to design new bridges. This paper deals with the three dimensional vibration analysis of prestressed concrete bridges under moving vehicles. The prestressed bridges are modeled by four-node isoparametric flat shell elements with the transverse shearing deformation taken into account. The usual five degrees-of-freedom (DOFs) per node of the element are appended with a drilling DOF to accommodate the transformation of the local stiffness and mass matrices to the global coordinates. The vehicle is modeled as a single or two-DOF system. A single-span prestressed Tee beam and two-span prestressed box-girder bridge are studied as the two numerical examples. The effects of prestress forces on the natural frequencies and dynamic responses of the bridges are investigated.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.12
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• pp.47-53
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• 2000

The casing oscillator is a construction equipment to clamp, oscillate and push a casing for foundation work. In case that the casing oscillator is operated on the slant ground, if another construction heavy equipment is not used, it is impossible to insert the casing in ground using only casing oscillator. So in this paper, we present the new casing oscillator that need not to level the ground for work of casing insertion. This mechanism can execute 4 DOF motion by actuating 5 single - rod hydraulic cylinders. The inverse kinematics analysis of the casing oscillator is performed and we verify the validity of kinematics analysis through the experiment.

• Smart Structures and Systems
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• v.25 no.4
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• pp.393-399
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• 2020

In this paper, the design method and experimental validation for the two-degree-of-freedom (2DOF) electromagnetic energy harvester are presented. The harvester consists of the rigid body suspended by four tension springs and electromagnetic transducers. Once the two resonant frequencies and the mass properties are specified, both the constant and the positions for the springs can be determined in the closed form. The designed harvester can locate two resonant peaks close to each other and forms the extended frequency bandwidth for power harvesting. Halbach magnet array is also introduced to enhance the output power. In the experiment, two resonant frequencies are measured at 34.9 and 37.6 Hz and the frequency bandwidth improves to 5 Hz at the voltage level of 207.9 mV. The normalized peak power of 4.587 mW/G² is obtained at the optimal load resistor of 367 Ω.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.237-240
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• 1997

The casing oscillator is a construction equipment to clamp, oscillate and push a casing for foundation work. In case that the casing oscillator is operated on the slant ground, if another construction heavy equipment is not used, it is impossible to insert the casing in ground using only casing oscillator. So in this paper, we present the new casing oscillator that need not to level the ground for work of casing insertion. This mechanism can execute 4 DOF motion by actuating 5 single - rod hydraulic cylinders. The forward kinematics analysis of the casrng oscillator by tetrahedron geometry is performed so predict workspace, direction and poison of casing oscillatoer.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.37 no.4
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• pp.71-79
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• 2000

The original March algorithms cannot detect CMOS ADOFs(Address Decoder Open Faults) which requires separate deterministic test patterns. Modified March algorithm using DOF(Degree of Freedom) was suggested to detect these faults in addition to conventional stuck faults. This paper augments the modified march test to further capture NPSFs(Neighborhood Pattern Sensitive Faults). Complete CA(Cellular Automata) is used for address generation and Rl-LFSRs(Randomly Inversed LFSRs) for data generation. A new modified March algorithm can detect SAF, CF, TF, CMOS ADOFs, and part of NPSFs. Time complexity of this algorithm is still O(n).