• Journal of the Optical Society of Korea
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• v.12 no.2
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• pp.79-87
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• 2008

We have developed a miniature fisheye lens with $190^{\circ}$ field of view operating simultaneously in the visible and the near infrared wavelengths. The modulation transfer function characteristic for the visible wavelength is sufficient for a mega-pixel-grade image sensor. The lens also has a fair resolution in the infrared wavelength region. The calibrated $f-{\theta}$ distortion is less than 5%, and the relative illumination is over 90%. In consequence, a sharp wide-angle image can be obtained which is uniform in brightness over the entire range of field angles. The real image heights for the visible and the near infrared wavelengths have been fitted to polynomial functions of incidence angle with sub-pixel accuracies. Combined with the near equidistance projection scheme of the lens, this lens can be advantageously employed in various image-processing applications requiring a wide-angle lens.

• Proceedings of the KIEE Conference
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• 1999.07a
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• pp.397-399
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• 1999

This paper deals with the torque characteristics of a AFPM motor excited by permanent magnets. According to relative angle difference of two rotor, torque characteristics are studied. According to varied angle of two rotor, torque ripple and, total torque of AFPM motor is different. For minimum torque ripple, angle of two rotor of AFPM motor are investigated. For this study, we used to Maxwell EM 3D program. A prototype AFPM motor have been assembled and driving power supply are made. Characteristics of magnetical and electrical characteristic are investigated.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.209-212
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• 2006

Bond between reinforcing bar and surrounding concrete is supposed to transfer load safely in the process of design of reinforced concrete structures. The effects of defomation properties on bond of reinforcing bars to concrete are studied. Beam-end tests are used to investigate the effects of machining of bars in addition to rib angle and relative rib area. The test results show that bond strength of machined bars were higher than the conventional bars produced in factory. Higher rib height bars with rib angle $30^{\circ}{\sim}60^{\circ}$ showed higher bond strength than lower rib height bars with low angle.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.19 no.3
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• pp.289-303
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• 2015

In this paper, an optimal guidance law with terminal angle constraint considering the seeker's lock-on condition, in which the target is located within the field-of-view (FOV) and detection range limits at the end of the midcourse phase, is proposed. The optimal solution is obtained by solving an optimal control problem minimizing the energy cost function weighted by a power of range-to-go subject to the terminal constraints, which can shape the guidance commands and the missile trajectories adjusting guidance gains of the weighting function. The proposed guidance law can be applied to both of the midcourse and terminal phases by setting the desired relative range and look angle to the final interception conditions. The performance of the proposed guidance law is analyzed through nonlinear simulations for various engagement conditions.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2003.10a
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• pp.225-225
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• 2003

• Journal of Korea Multimedia Society
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• v.17 no.9
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• pp.1092-1097
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• 2014

It is difficult to perform automatic formation flight of UAV (Unmanned Aerial vehicle) when GPS (Global Positionig System) is out of order or has a system error, since the relative position estimation in the flight group is impossible in that case. In this paper, we design a relative localization system for the automatic formation flight of UAV. For this purpose, we adopt digital beam forming (DBF) to estimate the angle with the central controller of the flight group and Particle Filtering scheme to compensate the estimation error of ToA (time of arrival) method. Computer simulation results present a proper distance between the central controller and a following unit to maintain the automatic formation flight.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05a
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• pp.278-281
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• 2006

The aims of this study are to investigate rib geometries of reinforcing bars commercially available in Korea, Japan and USA, and evaluate bond performance using beam-end test specimens. Measurement of rib geometries of the bars include nominal area, average distance of rib, height of rib and an angle of rib perpendicular to bar axis. The result of this study show that rib height of Korean reinforcement bars are much less than those of Japan and USA resulting in the lowest value of relative rib area. Average bond strength of Korean D25 deformed bars is known as 9 % less than that of bars produced in USA. Bond strength depends primarily on the relative rib area. Bond strength of the high relative rib area bars produced in USA show 18% higher than that of bars produced in Korea.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.82-89
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• 2004

To secure stability and availability of Rammed Aggregate Pier method as the foundation of a structure, the shear strength characteristics according to the area replacement ratio of RAP and the relative density of in-situ ground was studied through soil laboratory tests and large direct shear tests in a model ground. As a result, the internal friction angle tends to increase in proportion to in-situ relative density(Very Loose, Loose, Medium) in composite ground formed by the same area replacement ratio of RAP and also increase in proportion to increasing the area replacement ratio(30, 40, 50%) of RAP in the same ground condition. Furthermore, the comparative analysis between the experimental value and theoretical value of the shear strength is carried out.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.7
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• pp.728-733
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• 2009

This paper presents the compensation of mechanical deflection error in SCARA robot. End of robot gripper is deflected by weight of arm and pay-load. If end of robot gripper is deflected constantly regardless of robot configuration, it is not necessary to consider above mechanical deflection error. However, deflection in end of gripper varies because that moment of each axis varies when robot moves, it affects the relative accuracy. I propose the compensation method of deflection error using neural network. FEM analysis to obtain the deflection of gripper end was carried out on various joint angle, the results is used in neural network teaming. The result by simulation showed that maximum relative accuracy reduced maximum 9.48% on a given working area.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.3
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• pp.411-418
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• 2000

By calculating the location and size of the relative eddy formed in the rotating impellers with the logarithmic spiral vanes, a new simple but accurate slip factor is analytically derived. The proposed slip factor depends on only one parameter that is a function of the number of vanes and the vane exit angle. Predicted slip factor for various cases are compared with those estimated by a number of previous slip factors as well as a recent theoretical calculation by Visser et al. ( JFM, Vol. 268, pp. 107-141, 1994). It is found that the present slip factor yields almost similar results to Wiesner's which has been empirically formulated based on the theoretical calculation of Busemann.