• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.22 no.3
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• pp.208-213
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• 2012

With great advancement of the automobile functions, environmental factors become important performances, especially noise. This paper investigates noise sources of outer rotor type BLDC motor using in the air-conditioner of the automobiles. To this end, this paper is analyzed two viewpoints, structural and electromagnetic causes. Structural analysis is conducted through modal test and analysis. For modal analysis, 3D finite element analysis is carried out using commercial program ansys. Electromagnetic causes are analyzed from local force that is computed by Maxwell stress tensor method. Local force excites structure of motor directly. Finally, correlation analysis is performed to determine effect between noise causes.

• Journal of the Korean Society of Industry Convergence
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• v.21 no.1
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• pp.37-44
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• 2018

In this work, a 4-DOF industrial robot system with three translational and one rotational motions which is widely used in palletizing applications is developed. In order for small robot manufacturing companies to develop their own robot systems for CNC machining and/or general automations, the analysis and design methods of a 4-DOF robot manipulator are presented and the development of a PC-based robot controller with EtherCAT are introduced. It is noted that the robot controller is developed by using Simulink Real-Time, which can provide an integrated environment of easier control algorithm development and data logging. Through position control and accuracy/repeatability measurement results, the developed robot prototype has comparable performances with commercial counterparts. In the future works, the advanced functions of industrial robots such as kinematic calibration, vibration suppression control, computed torque control, etc. will be investigated.

• Journal of Mechanical Science and Technology
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• v.18 no.4
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• pp.573-581
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• 2004

A self-contained wall climbing robot, called MRWALLSPECT (Multi-functional Robot for WALL inSPECTion) II, is developed. It is designed for scanning external surfaces of gas or oil tanks with small curvature in order to find defects. The robot contains all the components for navigation in itself without any external tether cable. Although it takes the basic structure of the sliding body mechanism, the robot has its original characteristic features in the kinematic design with closed link mechanism, which is enabled by adopting a simple and robust gait pattern mimicking a biological system. By employing the proposed link mechanism, the number of actuators is reduced and high force-to-weight ratio is achieved. This paper describes its mechanism design and the overall features including hardware and software components. Also, the preliminary results of experiments are given for evaluating its performances.

• Journal of Institute of Control, Robotics and Systems
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• v.5 no.2
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• pp.208-219
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• 1999

Springs have been employed in a wide range of mechanical systems. This work deals with the concept of an adaptable spring mechanism which can arbitrarily modulate its spring characteristics. The adaptable spring is desired for enhancing performances of various mechanical systems employing springs. We demonstrate that such adaptable springs can be realized by adapting anthropomorphic musculoskeletal structures of the human upper-extremity, which possesses highly nonlinear kinematic-coupling among redundant muscles existing in its structures. This phenomenon has been explained by several human arm models. Based on the analysis results, we propose multi-degree-of-freedom spring mechanisms resembling the musculoskeletal structure of the human upper-extremity, and verifiy the applicability of these mechanisms through simulation.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.7
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• pp.694-699
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• 2009

This paper presents the implementation of the real-time object tracking control of the ROBOKER head. The visual servoing technique is used to track the moving object, but suffers from ill-estimated Jacobian of the virtual link design. To improve the tracking performance, the RBF(Radial Basis Function) network is used to compensate for uncertainties in the kinematics of the robot head in on-line fashion. The reference compensation technique is employed as a neural network control scheme. Performances of three schemes, the kinematic based scheme, the Jacobian based scheme, and the neural network compensation scheme are verified by experimental studies. The neural compensation scheme performs best.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.463-468
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• 2011

According to a quantum leap of the performances of automobile, environmental factors are important as functional factors, especially noise. BLDC motor, one of the part of automobile, is also no exception. In this paper, investigation of the sound sources of outer rotor type BLDC motor is performed. In order to reduce noise, it must be necessary knowing sound source. To this end, this paper is analyzed two viewpoints, structural and electromagnetic causes. For structural analysis, modal experiment and 3D mode analysis are performed. On behalf of electromagnetic analysis, 2D finite element method is carried out. Finally, coupling analysis is performed in order to know about influence between two factors.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1994.10a
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• pp.901-906
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• 1994

In designing and evaluating manipulators, itis important to understand the capability of kinematic and static performances. Both workspace and manipulability can be considered as such performance measures. In general, the measure of manipulability is related to the kinematics for serial type manipulators. However.in case of parallel manipulators such as Stewart Platform, the manipulability can be interpreted as the static capability of transforming the input forces of actuators to the wrench of the end-effector. In this paper, the mathematical and physical meanings of manipulability suggested in some research works have been examined, and more meaningful measure of manipulability using the absolute minimum eigenvalues of J $^{T}$ .del. J has been suggested, which has been applied to a Stewart Platform in order to investigate the manipulability of this mechanism..

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.4
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• pp.129-140
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• 1998

A numerical method is proposed to optimize automotive cam profiles. An acceleration curve of a cam follower motion is described by Hermite spline curves. Because of the intrinsic characteristics of the Hermite curve, it is possible to design an acceleration curve with arbitrary shape. Design variables in the optimization problem are location of control points which define the acceleration curve. Objective function includes dynamic performances as well as kinematic properties of a valve train. Similar optimization procedure was also performed using Polydyne cam profile synthesis method. Optimized profiles using the Hermite curve are proved to be superior to those using the Polydyne method.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1990.04a
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• pp.18-23
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• 1990

The paper is concerned with the elasto-plastic and geometrically nonlinear analysis of shell structures using an improved degenerated shell element. In the formulation of the improved degenerated shell element, an enhanced interpolation of transverse shear strains in the natural coordinate system is used to overcome the shear locking problems; the reduced integration technique in in-plane strains is applied to avoid membrane locking behavior; selective addition the nonconforming displacement modes improve the element performances. This element is free of serious locking problems and undesirable compatible or commutable spurious kinematic deformation modes and passes the patch tests. An incremental total Lagrangian formulation is presented which allows the calculation of arbitrarily large displacements and rotations. The resulting nonlinear equations are solved by the Newton-Raphson solution scheme. The versatility and accuracy of this improved degenerated shell element are demonstrated by solving several numerical examples.

• Korean Journal of Applied Biomechanics
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• v.21 no.4
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• pp.421-427
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• 2011

The purpose of this study was to analyze the difference between male and female tennis players' two-handed backhand stroke and to provide basic data which helps precise and efficient instruction for the sake of precise postures, enhanced performances and skills. 5 male and 5 female university players were recruited as subjects, and the mean difference between the kinematic variables such as the time from backswing to impact and total swing time, racket head velocity, change of the center of body gravity in two-handed backhand stroke through three-dimensional motion analysis. The test data was analyzed by t-test, and the alpha level of ${\alpha}$=.05 was set for all tests of significance. The findings of the study were as follows; First, there was no difference in the time from backswing to impact and total time of