• The Journal of Korea Robotics Society
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• v.13 no.1
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• pp.63-71
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• 2018

This paper describes a study on posture control of the multi-legged biomimetic underwater robot (CALEB10). Because the underwater environment has a feature that all degrees of freedom are coupled to each other, we designed the posture control algorithm by separating each degree of freedom. Not only should the research on posture control of underwater robots be a precedent study for position control, but it is also necessary to compensate disturbance in each direction. In the research on the yaw directional posture control, we made the drag force generated by the stroke of the left leg and the right leg occur asymmetrically, in order that a rotational moment is generated along the yaw direction. In the composite swimming controller in which the controllers in each direction are combined, we designed the algorithm to determine the control weights in each direction according to the error angle along the yaw direction. The performance of the proposed posture control method is verified by a dynamical simulator and underwater experiments.

• Applied Microscopy
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• v.27 no.4
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• pp.483-488
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• 1997

A misfit dislocation generation in InAs epilayers grown on (001) InP substrates (oriented $2^{\circ}$ off (001) toward the [110] direction) using metalorganic chemical-vapor deposition was studied. The InAs film of 17 nm thickness grown at $405^{\circ}C$ showed the three different arrays of dislocations: a straight orthogonal array to the <110> direction, an array to the >100> direction, and an array tilted by a degree of $5\sim45^{\circ}$ from the [110] direction. All of the dislocations had a/2<101> Burgers vectors inclined $45^{\circ}$ to the interface. Upon annealing at $660^{\circ}C$ the InAs films with 60, 140 and 220 nm thicknesses, most of the misfit dislocations became the Lomer type $(\sim100%)$ oriented exactly along the >110> direction. These misfit dislocation spacings were decreased with increasing the InAs thickness up to 220 nm thickness. This phenomena was interpreted by the relationship between the dislocation interaction energy among parallel misfit dislocations and the opposite remnant InAs epilayer strain energy. The distance between misfit dislocations was measured by transmission electron microscopy.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.2
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• pp.126-132
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• 2012

The technique for estimation of sound source direction is one of the important methods necessary for various engineering fields such as monitoring system, military services and so on. As a new approach for estimation of sound source direction, this paper propose the bio-mimetic localization sensor based on mechanically coupling structure motivated by hearing structure of fly, Ormia Ochracea. This creature is known for its outstanding recognition ability to the sound which has large wavelength compared to its own size. ITTF (Inter-Tympanal Transfer Function) which is the transfer function between displacements of the tympanal membranes on each side has the all inter-tympanal information dependent on sound direction. The peak and notch features of desired ITTF can be generated by using the appropriate mechanical properties. A example of estimation of sound source direction using generated ITTF with monotonically changing notch and peak patterns is shown.

• Journal of KIISE:Software and Applications
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• v.31 no.12
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• pp.1581-1590
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• 2004

We present a robust off-line method recognizing handwritten digits by only using stroke direction codes as a feature of handwritten digits. This method makes general 8-direction codes for an input digit and then has the multi-layered neural networks learn them and recognize each digit. The 8-direction codes are made of the thinned results of each digit through SOG*(Improved Self-Organizing Graph). And the usage of these codes simplifies the complex steps processing at least two features of the existing methods. The experimental result shows that the recognition rates of this method are constantly better than 98.85% for any images in all digit databases.

• Journal of Welding and Joining
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• v.23 no.5
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• pp.20-24
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• 2005

Due to the difficulties associated with the supply of steel plates, hot rolled coil (Steel grade: SM490A) is considered fur structural materials in replace of the existing SWS50A-M1. However, it is found that SM490A exhibits a significant anisotropy in terms of impact energy with respect to transverse and longitudinal directions. In this study, an experimental investigation is carried out to examine the relationship between the anisotropy in impact values and the fatigue strengths of SM490A with respect to the rolling direction of test specimens. All test specimens failed around 1,500,000 cycles regardless of the test specimen direction. Therefore, it is found that the anisotropy in impact energy is not related to the fatigue strength of the materials considered in this study. However, the transverse direction specimen showed more rapid brittle fracture mode compared to that of longitudinal direction specimen, and this appears to be related to the lower impact values in transverse direction.

• Journal of Magnetics
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• v.7 no.4
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• pp.147-150
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• 2002

The pinning direction, the spin flop behaviors and the magnetoresistive properties in top synthetic spin valve structure [NiFe/CoFe/Cu/CoFe (t$_{p2}$)/Ru/CoFe (t$_{p1}$)/IrMn] were investigated. The magnetoresistive and pinning characteristics of synthetic spin valves strongly depended on the differences in the two pinning layer thickness, ${\Delta}t(=t_{p2}-t_{p1})$. In contrast to the conventional spin valves, the pinning direction (P1) was canted off with respect to the growth field axis with ${\Delta}t$. We found that the canting angle ${\Phi}$ had different values according to the annealing field direction and ${\Delta}t$. When the samples were annealed at above the blocking temperature of IrMn with zero fields, the canted pinned layer could be set along the growth field axis. Because the easy axis which was induced by the growth field during deposition is still active in all ferromagnetic layers except the IrMn at $250{^{\circ}C}$, the pinning direction could be aligned along the growth field axis, even in 0 field annealing.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2845-2850
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• 2007

Flow-induced forces on two identical nearby circular cylinders immersed in the cross flow at Re =100 were numerically studied. We consider all possible arrangements of the two circular cylinders in terms of the distance between the two cylinders and the inclination angle with respect to the direction of the main flow. It turns out that significant changes in the characteristics of flow-induced forces are noticed depending on how the two circular cylinders are positioned, resulting in quantitative changes of force coefficients on both cylinders. Collecting all the numerical results obtained, we propose a contour diagram for drag coefficient and lift coefficient for each of the two cylinders. The perfect geometrical symmetry implied in the flow configuration allows one to use those diagrams to estimate flow-induced forces on two identical circular cylinders arbitrarily positioned in physical space with respect to the main flow direction.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2890-2895
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• 2007

Heat transfer on two identical nearby circular cylinders immersed in the uniform cross flow at Re = 100 and Pr = 7.0 was numerically studied. We consider all possible arrangements of the two circular cylinders in terms of the distance between the two cylinders and the inclination angle with respect to the direction of the main flow. It turns out that significant changes in the characteristics of heat transfer are noticed depending on how the two circular cylinders are positioned, resulting in quantitative changes of heat transfer coefficients on both cylinders. Collecting all the numerical results obtained, we propose a contour diagram for averaged Nusselt number for each of the two cylinders. The perfect geometrical symmetry implied in the flow configuration allows one to use those diagrams to estimate heat transfer rates on two identical circular cylinders arbitrarily positioned in physical space with respect to the main flow direction.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2851-2856
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• 2007

Flow patterns in the presence of two identical nearby circular cylinders at =100 were numerically studied. We considered all possible arrangements of the two circular cylinders in terms of the distance between the two cylinders and the inclination angle with respect to the direction of the main flow. Eight distinct flow patterns were identified based on vorticity contours and streamlines, which are Base-Bleed, Biased-Base-Bleed, Shear- Layer-Reattachment, Induced-Separation, Vortex-Impingement, Flip-Flopping, Modulated Periodic, and Synchronized-Vortex-Shedding. Collecting all the numerical results, we propose a general flow pattern diagram for flows past the two cylinders. The perfect geometrical symmetry implied in the flow configuration allows one to use this diagram to distinguish flow patterns in the presence of two identical circular cylinders arbitrarily positioned in physical space with respect to the main flow direction.

• Journal of computational fluids engineering
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• v.13 no.2
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• pp.42-47
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• 2008

Heat transfer on two identical nearby circular cylinders immersed in the uniform cross flow at Re=120 and Pr=0.7 was numerically studied. We consider all possible types of arrangements of the two circular cylinders in terms of the distance between the two cylinders and the inclination angle with respect to the direction of the main flow. It turns out that significant changes in the characteristics of heat transfer are noticed depending on how the two circular cylinders are positioned, resulting in quantitative changes of heat transfer coefficients on both cylinders. Collecting all the numerical results obtained, we propose a contour diagram for averaged Nusselt number for each of the two cylinders. The perfect geometrical symmetry implied in the flow configuration allows one to use those diagrams to estimate heat transfer rates on two identical circular cylinders arbitrarily positioned in physical space with respect to the main flow direction.