• Proceedings of the KSME Conference
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• 2000.04a
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• pp.809-813
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• 2000

In this study, screw machining system by use of a rotational tool such as an end-mill or a face cutter with Y axis off-set on a CNC turing center was developed for quick machining. In this system, It was possible to use different tools for different processes, and by off-setting the tool in Y direction by calculated amount it was possible to avoid tool interference problem which could occur within the central area at the end of a tool. In addition, machining a screw with a helix of up to 3 different leads combined and with tapered minor diameter was possible.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.47 no.3
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• pp.187-194
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• 2019

The off-axis Infra-Red(IR) seeker is mounted on the nose cone side of the anti-air high speed missile to alleviate thermal shield effect due to aerodynamic heating. The seeker output can not be regarded as the Line-of-Sight(LOS) rate any more as missile's roll motion to keep the target tracking is associated. In this paper, we propose a method to calculate the LOS rate for off-axis seeker on a 2-axis gimbal. Firstly, true LOS rate equations are analytically derived but not implementable because boresight error rate is not measurable. And then the first order lag approximation to obtain boresight error rate is proposed. The proposed LOS rate calculation method can compensate the coupling effect by considering the rotations of missile and gimbal. The performance of the proposed method is verified via full nonlinear 6-DOF(Degree of Freedom) simulations.

• Proceedings of the Materials Research Society of Korea Conference
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• 2002.11a
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• pp.159-159
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• 2002

• Proceedings of the Materials Research Society of Korea Conference
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• 2002.11a
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• pp.57-57
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• 2002

• Korean Journal of Optics and Photonics
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• v.9 no.3
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• pp.191-198
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• 1998

A method is described to produce off-axis hologram lenses without astigmatism for semiconductor lasers. We fabricated a holographic collimating lens by using dichromated gelatin film with high diffraction efficiency and without astigmatism which makes a collimated off-axis beam of semiconductor laser. We have designed the holographic collimating lens by applying the classical ray-tracing method to holographic diffraction. The elimination of astigmatism is obtained by choosing appropriate angles of recording and reconstruction beams. The hologram is recorded by use of Ar^{+}$ laser (488nm wavelength) and reconstructed by semiconductor laser(670nm wavelength). The physical parameters of recording and reconstruction angles, wavelength, and astigmatism are analytically calculated and experimentally confirmed.

• Korean Journal of Optics and Photonics
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• v.20 no.6
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• pp.328-333
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• 2009

We proposed a three-dimensional holographic display technique without twin image noise by converting a complex hologram to an off-axis hologram. To implement the proposed technique we record the complex hologram of a three dimensional object that is composed of two slides located with different depth locations. We added spatial carrier to the complex hologram and after that, extract the real part of the spatial-carrier-added hologram. This converts the complex hologram to an off-axis hologram. We also reconstruct the off-axis hologram using a spatial light modulator for three dimensional display.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2006.05a
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• pp.611-614
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• 2006

Resolution 122 requires to study power limitation applicable for HAPS ground stations to facilitate sharing with space station receivers in 47/48GHz bands. ITU-R Recommendation 1481-1 recommends to improve the side lobe characteristics of HAPS ground station antenna for sharing between FSS system and HAPS system. Thus, in this paper, we propose maximum allowable off-axis e.i.r.p. level of HAPS ground station antennas by considering power limitation to HAPS ground station in Resolution 122 in order to reduce unfeasible separate distance between HAPS and GSO FSS service coverage and improve the side lobe characteristics of HAPS ground station antennas in Recommendation SF.1481-1.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.11 no.3
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• pp.459-464
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• 2007

Resolution 122 requires to study power limitation applicable for HAPS ground stations to facilitate sharing with space station receivers in 47/48GHz bands. ITU-R Recommendation 1481-1 recommends to improve the side lobe characteristics of HAPS ground station antenna for frequency sharing between FSS system and HAPS system. In this paper, we propose the maximum allowable off-axis e.i.r.p. level of HAPS ground station antennas by considering power limitation to HAPS ground station in Resolution 122, and by improving the side lobe characteristics of HAPS ground station antennas in Recommendation SF.1481-1. The simulation results show that the unfeasible sharing distance between HAPS ground station and FSS earth station can be reduced remarkably, and give the possibility of frequency sharing between two above systems.

• Korean Journal of Optics and Photonics
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• v.15 no.6
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• pp.527-530
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• 2004

Using a polarimetry based on the rotating analyzer ellipsometer, a technique of measuring off-alignment angle between the slow-axis of the LCD (Liquid Crystal Display) polarizing plate and the transmission axis of the compensating plate attached to the polarizing plate is proposed. It is anticipated that this technique will reduce the optic axis off-alignment error coming from the process of attaching the compensating plate to the LCD polarizing plate markedly, and therefore will help maintain the quality of LCD display image uniformly.

• Korean Journal of Optics and Photonics
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• v.32 no.6
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• pp.296-305
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• 2021

This paper reports a study on the long axis performance of the line beam optics used in laser lift-off equipment for the OLED manufacturing process. The centration errors of the cylindrical lens are classified and defined in seven categories, and the measurement methods are presented. The cylindrical fly-eye lens is analyzed theoretically and experimentally to find the influence of the surface shape error and decentering error on the long axis performance of the line beam optics system. A future research direction is also presented to improve the long axis performance.