• Journal of Institute of Control, Robotics and Systems
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• v.20 no.3
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• pp.333-344
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• 2014

This is the survey paper on the role of kinematics in robot development. The robot is considered as a form of mechanical systems which includes closed-chain loop system, open-chain loop system and closed and open switching system. To analyze these systems, kinematic notations has been developed in kinematics of mechanical theory since 1955 and has been applied in robotics. Several kinematic notations including Denavit-Hartenberg notations have been reviewed. The status of development of the spherical motor which has a great impact on the future robot advancement has reviewed, and research activity on a spherical motor and its application to 3-D spatial mechanisms at UNIST is introduced. For the open and closed switching mechanical systems, the bipedal robots' walking theories using Zero Moment Point are reviewed. And current status regarding bipedal robots based on newly developed passive dynamic walking theory is reviewed with the research activity at UNIST on this subject.

• Proceedings of the KIEE Conference
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• 2008.10c
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• pp.6-8
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• 2008

Electrical machineries have been developed as following with various and high technical application in these days. Especially the robot is integrated system including mechanical structure, electronic control, and electrical technology. The robot system is not compact and has not natural motion like human, although the technology of robot has been developing continuously. The spherical wheel motor is useful electric machine for using robot joint as operation of 3-degrees of freedom. In this paper, a permanent magnet spherical wheel motor is introduced and performance characteristics are analyzed for improving of operation stability.

• Journal of Electrical Engineering and Technology
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• v.9 no.5
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• pp.1544-1550
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• 2014

In this paper, an adaptive optimization strategy utilizing Kriging model and genetic algorithm is proposed for the optimal design of electromagnetic devices. The ordinary Kriging assisted by the spherical covariance model is used to construct surrogate models. In order to improve the computational efficiency, the adaptive uniform sampling strategy is applied to generate sampling points in design space. Through several iterations and gradual refinement process, the global optimal point can be found by genetic algorithm. The proposed algorithm is validated by application to the optimal design of a switched reluctance motor, where the stator pole face and shape of pole shoe attached to the lateral face of the rotor pole are optimized to reduce the torque ripple.

• Proceedings of the KIEE Conference
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• 2007.04c
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• pp.138-140
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• 2007

These days, robot-industry development requires a new motor technology. Robot system is more complex than the other machine ones. They need the simplicity and light weight as robot systems. Moreover, They have to become a high energy efficiency machine. For these reasons, in this paper, the 3-degrees of freedom permanent-magnet spherical motor is proposed instead of existing ones. The proposed motor model is analyzed by using FEA(Finite Element Analysis), for comparing the results, torque of the motor is simulated by derived torque function.

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.97.1-97.1
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• 2008

• Proceedings of the Korean Magnestics Society Conference
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• 2008.12a
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• pp.99.1-99.1
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• 2008

• Proceedings of the Optical Society of Korea Conference
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• 1999.08a
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• pp.128-129
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• 1999

Polygon Mirror Scanning(PMS) is composed of LED array, magnifying lens, polygon mirror and motor. It is important to correct the lens aberrations to gain the image we want to show. In this paper, we have simulated the lens aberration correction to reduce the spherical aberration . We have obtained a aspherical lens which is corrected the spherical aberration.

• Journal of Electrical Engineering and Technology
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• v.13 no.6
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• pp.2158-2167
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• 2018

This paper analyzed the magnetic field produced by the cylindrical stator coils of permanent magnet spherical motor (PMSM). The elliptic equations about the vector magnetic potential were given. Given that the eddy current effects are neglected, the magnet field of the PMSM is regarded as irrotational field, which can be calculated by scalar magnetic potential. The current density of cylindrical stator coil was proposed based on the definition of current density. The expression of current density of stator coil was obtained according to the double Fourier series decomposition and spherical harmonic functions. Then the magnetic flux density for scalar magnetic potential was derived. Further, the influence of different parameters on radial flux density was also analyzed. Finally, the results by the analytical method in this paper were validated by finite element analysis (FEA).

• Journal of Electrical Engineering and Technology
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• v.5 no.3
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• pp.431-434
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• 2010

This paper presents the torque calculation method of a permanent magnet spherical motor. To calculate using the finite element method (FEM), three-dimensional (3D) FEM must be used. However, since the method requires excessive time and memory, an easier torque calculation method is hereby presented. In the proposed method, it is very important to obtain the approximation function of the torque profile curve. We present the approximation method of the torque profile curve and show that the torque calculation result can approximate the torque obtained by 3-D FEM.

• Applied Microscopy
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• v.26 no.3
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• pp.329-348
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• 1996

The prenatal development of lateral motor columns in the lumbar spinal cord was studied by electron microscopy in human embryos and fetuses ranging from 9 mm to 260 mm crown-rump length ($5{\sim}30$ weeks of gestational age). At 9 mm embryo, the lateral motor column were developed from ventro-lateral projection into the marginal layer and composed of primitive neuroblasts. At 20 mm embryo the primitive motor neurons were packed closely together and could readly be distinguished from primitive glioblasts by a presence of large nuclei. The primitive multipolar neurons were observed in lateral motor column at 40 mm fetus. At 80 mm fetus multipolar neurons were characterized by their many dendrites and axons in the vicinity of motor neuron perikarya. At 260 mm fetus, the motor neurons were large and contained all intracytoplasmic structures in the cytoplasm which were also found in mature motor neuron in lateral motor column. The first axo-dendritic synapses found at 40 mm fetus and increased in number throughout fetal development. Axo-somatic synapses with spherical vesicles were first observed at 80 mm fetus. A few axo-somatic synapses were found at next prenatal stages. Axo-dendritic and axo-somatic synapses contained mixed populations of spherical and flattened vesicles by 120 mm fetus. These findings indicate that axo-dendritic synapses develop prior to axo-somatic synapses in the spinal cord during neurogenesis.