• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1555-1560
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• 2000

Recently, optical pickup actuators have been designed to have structures that extruded lens to decrease their height, because they are used in very thin drive for notebook computers. However, because of discordant and undesirable of forces that are supposed to happen in this design feature, subsidiary resonance such as rolling and pitching mode exert bad influence on actuator. In this paper, we presented force constituents to clarify the cause of subsidiary resonance and proposed new finite element analysis method to calculate force precisely, and performed frequency response analysis to evaluate characteristics of actuators. As a result, we could find out design parameters to diminish the influence of subsidiary resonance. Sample actuators designed with appropriate parameters were fabricated and put to practical tests. Comparing analysis with experimental results, we verified the accuracy of the analysis and the effectiveness of the method presented.

• Korean Journal of Optics and Photonics
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• v.13 no.4
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• pp.324-331
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• 2002

The fundamentals of light-emitting diode lamp design are presented. The shapes of the reflecting cup and lens employed in LED lamps can be flexibly adjusted, over a relatively large range, by using a few parameters. The analysis of the designed lamps by Monte Carlo photon simulation shows that diverse far-field beam patterns required in various application areas can be achieved.

• Design & Manufacturing
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• v.6 no.1
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• pp.12-17
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• 2012

In order to produce high-quality optical components, aspheric lenses have been widely applied in recent years. An aspheric lens consists of aspheric surfaces instead of spherical ones, which causes difficulty in the design process as well as the manufacturing procedure. Although injection molding is widely used to fabricate optical lenses owing to its high productivity, there remains lots of difficulty to determine appropriate mold design factors and injection molding parameters. In the injection molding fields, computer simulation has been effectively applied to analyze processes based on the shell analysis so far. Considering the geometry of optical lenses, a full-3d simulation based on solid elements has been reported as a reliable approach. The present work covers three-dimensional injection molding simulation and relevant deformation analysis of an injection molded plastic lens based on 3d solid elements. Numerical analyses have been applied to the injection molding processes of three aspheric lenses for an image sensing module of a mobile phone. The reliability of the proposed approach has been verified in comparison with the experimental results.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.12
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• pp.1997-2003
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• 2003

Recently, there have been many researches and developments in optical disc drive by high density of track and high access speed. Therefore, the optical pick-up should guarantee highly accurate dynamic characteristics for the wide bandwidth in order to cope with this trend. These demands for optical pick-up actuator can be solved by improvements of lens-holder through the following methods. The first way is the analysis of the sensitivity matrix of design variables for vibration modes after appropriate design parameters are selected like shapes and local dimensions of a lens-holder. The second way is the optimization of design variables by calculating sequential linear programming after the problem of extending bandwidth are converted to problem of minimizing adequate objective function. In the result, modified FE model is obtained through several iterations by finite difference scheme(FDS). While results of the first way show better convergence of the target frequency, the second result shows better reduction of mass increase.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.12
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• pp.1269-1275
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• 2003

In this paper, nonradiative dielectric(NRD) rotman lens with a gap-coupled unidirectional dielectric radiator(UDR) has been designed. Gap-coupled UDR is structurally suitable for NRD rotman lens. We have optimized NRD rotman lens for minimizing side-lobe, and calculated design parameters of UDR such as length of resonator and distance of gap using an equivalent circuit model of an evanescent NRD guide. Experimental prototype of UDR is fabricated and measured at the center frequency of 38 GHz. The simulated S-parameter and far-field radiation beam pattern of UDR show good agreements with measured data. Finally, total beam pattern of NRD rotman lens of multi-beam feed has been obtained using a measured pattern of UDR and array factor of NRD rotman lens. The obtained beam pattern shows remarkably suppressed side-lobe.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.743-746
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• 2000

Plastic microlenses play an important role in reducing the size, weight, and the cost of the systems in the fields of optical data storage and optical communication. In the present study, plastic microlens arrays were fabricated using micro-compression molding process. The design and fabrication procedures for mold insert were simplified by using silicon instead of metal. A simple but effective micro compression molding process, which uses polymer powder, were developed for microlens fabrication. The governing process parameters were temperature and pressure histories and the micromolding process was controlled such that the various defects developing during molding process were minimized. The radius and magnification ratio of the fabricated microlens were $125{\mu}m$ and over 3.0, respectively.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.8
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• pp.1242-1245
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• 2001

Plastic microlenses play an important role in reducing the size, weight, and the cost of the systems in the fields of optical data storage and optical communication. In the present study, plastic microlens arrays were fabricated using micro-compression molding process. The design and fabrication procedures for mold insert were simplified by using silicon instead of metal. A simple but effective micro compression molding process, which uses polymer powder, were developed for microlens fabrication. The governing process parameters were temperature and pressure histories and the micromolding process was controlled such that the various defects developing during molding process were minimized. The radius and magnification ratio of the fabricated microlens were 125$\mu\textrm{m}$ and over 3.0, respectively.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.3
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• pp.388-393
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• 2010

In recent years the research has been focused on the preparation of special glasses, i.e., chalcogenide and heavy metal oxide ones that can transmit optical radiation above 2 um and also other optical parameters exceed those of silica based glasses. The attention in this paper is focused on chalcogenide glasses, on preparation of high quality base glass, for an application in infrared optical product design and manufacture. The amorphous materials of As-Se and Ge-As-Se chalcogenides were prepared by a standard melt-quenching technique. The compositions were mesaured by ICP-AES and EPMA, and structural and thermal properties were studied through various annealing processes. Several anomalies of glass transition and crystallization were observed in the DSC/DTA/TG results of the chalcogenide glass.

• 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.

• Proceedings of the KIEE Conference
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• 2000.07b
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• pp.858-860
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• 2000

Recently, optical pickup actuators have been designed to have structures that extruded lens to decrease their height, because they are used in very thin drive for notebook computers. However because of discordant and undesirable of forces that are supposed to happen in this design feature, subsidiary resonance such as rolling and pitching mode exert bad influence on actuator. In this paper, we presented force constituents to clarify the cause of subsidiary resonance analysis to evaluate characteristics of actuators. As a result. we could find out design parameters to diminish the influence of subsidiary resonance. Sample actuators designed with appropriate parameters were fabricated and put to practical tests. Comparing analysis with experimental results, we verified the accuracy of the analysis and the effectiveness of the method presented.