• Journal of the Optical Society of Korea
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• v.18 no.1
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• pp.9-14
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• 2014

We numerically investigate the effect of sunlight polarization on the absorption efficiency of V-shaped organic solar cells (VOSCs) using the finite element method (FEM). The spectral distribution of absorbance and the spatial distribution of power dissipation are calculated as a function of the folding angle for s-and p-polarized light. The absorption enhancement caused by the light-trapping effect was more pronounced for s-polarized light at folding angles smaller than $20^{\circ}$, where s-polarized light has a relatively larger reflectance than p-polarized light. On the other hand, the absorption efficiency for p-polarized light is relatively larger for folding angles larger than $20^{\circ}$, where the smaller reflectance at the interface of the VOSC is more important in obtaining high absorption efficiency.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.12 s.255
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• pp.1557-1563
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• 2006

A scanning electron microscope (SEM) is well known as a measurement and analysis equipment in nano technology, being widely used as a crucial one in measuring objects or analyzing chemical components. It is equipped with an electron optical system that consists of an electron beam source, electromagnetic lenses, and a detector. The present work concerns numerical analysis for the electron optical system so as to facilitate design of each component. Through the numerical analysis, we investigate trajectories of electron beams emitted from a nano-scale field emission tip, and compare the result with that of experimental observations. Effects of various components such as electromagnetic lenses and an aperture are also discussed.

• Korean Journal of Optics and Photonics
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• v.3 no.2
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• pp.86-91
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• 1992

We describe the design of a soft X-ray grating monochromator for synchrotron radiation in the photon energy range 300~1200eV. We investigate the optimum condition in optical parameters of CEM (cylindrical element monochromator), whose performance is well known by Dragon beam line installed recently at Brookhaven National Laboratory by C. T. Chen, fitting the parameter of PLS (Pohang Light Source) storage ring construction.

• Journal of Institute of Control, Robotics and Systems
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• v.9 no.3
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• pp.251-258
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• 2003

Optical Switching Matrix (OSM) or Optical Multistage Interconnection Networks (OMINs) comprising photonic switches have been studied extensively as important interconnecting blocks for Optical Cross Connects (OXC) based on Optical Burst Switching (OBS). A basic element of photonic switching networks is a 2$\times$2 directional coupler with two inputs and two outputs. This paper is concerned with the diagnosis of multiple crosstalk-faults in OSM. As the network size becomes larger in these days, the conventional diagnosis methods based on tests and simulation become inefficient, or even more impractical. We propose a simple and easily implementable algorithm for detection and isolation of the multiple crosstalk-faults in OSM. Specifically. we develop an algorithm for isolation of the source fault in switching elements whenever the multiple crosstalk-faults arc detected in OSM. The proposed algorithm is illustrated by an example of 16$\times$16 OSM.

• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2009.10a
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• pp.323-327
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• 2009

Silicone is recently used for LED chip encapsulment due to its good thermal stability and optical transmittance. In order to predict residual stress which causes optical briefringence and mechanical warpage of silicone, finite element analysis was conducted for both curing and cooling process during silicone molding. For analysis of curing process, a cure kinetics model was derived based on the differential scanning calorimetry(DSC) test and applied to the material properties for finite element analysis. Finite element simulation result showed that the curing as well as the cooling process should be designed carefully so as to reduce the residual stress although the cooling process plays the bigger role than curing process in determining the final residual stress state.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.4
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• pp.295-302
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• 2004

In this study the optimization of a NFR suspension is performed using finite element method and experimental modal analysis. NFR suspensions are required to have low compliance modes to allow the slider to comply with the rotating disk, and high tracking stiffness modes to maximize the servo bandwidth of the tracking controller First of all, the dual suspension model is designed based on the characteristics of NFR drives. And the parametric study on the sensitivities of compliance modes and tracking stiffness modes is investigated. Finally, the model satisfying static characteristics is selected and shape optimization is performed to improve dynamic characteristics. A prototype of a NFR suspension is made by etching and modal ekperiment in free state is performed. The results of experiment almost agree with those of finite element method.

• Transactions of Materials Processing
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• v.24 no.2
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• pp.101-106
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• 2015

Recently, silicone is being used for LED chip lens due to its good thermal stability and optical transmittance. In order to predict residual stresses, which cause optical birefringence and mechanical warpage of silicone, a finite element analysis was conducted for the curing of silicone during molding. For the analysis of the curing process, a dynamic cure kinetics model was derived based on the results of a differential scanning calorimetry (DSC) testing and applied to the material properties for finite element analysis. Finite element simulation results showed that a step cure cycle reduced abrupt reaction heat and showed a decrease in the residual stresses.

• 한국정보통신설비학회:학술대회논문집
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• 2007.08a
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• pp.22-26
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• 2007

In the fibre to the home (FTTH) era, it is expected that broadband network provisioning will require thousands of optical fibres to be accommodated in a central office for optical access networks. An optical fibre line testing system could be used to reduce maintenance costs and improve service availability depending on the PON's element manager capabilities and the maintenance procedures adopted by the network supplier. When monitoring optical fibres transmitting communication lights, a wavelength of 1625 nm is used for maintenance testing. The splitter installed optical filters allow the communication light to pass but that cut off the test light in the front of optical line terminals (OLTs) and optical network terminals (ONTs). In the economic point of view, We design new planer lightwave circuit splitter embedded filtter and study it optical property.

• Proceedings of the Optical Society of Korea Conference
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• 2008.02a
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• pp.127-128
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• 2008

• The Transactions of the Korean Institute of Electrical Engineers D
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• v.55 no.5
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• pp.205-215
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• 2006

In this paper an optical power meter using Hadamard transform, which can be used in multiple channel optical elements alignment system, is proposed. A traditional optical power meter in multiple channel optical elements alignment system is able to judge how well the elements are aligned each other by measuring optical power of the first and the last two channels with at least two detectors. It has critical drawback that the alignment accuracy per channel is dependent on the number of detectors. The proposed optical power meter can get noise reduction by the Hadamard transform based multiplexing technique. The Hadamard transform based multiplexing technique using spatial light modulators is distinguished by the best enhancement of signal-to-noise ratio (SNR) for the reconstructed signals. Moreover, the noise reduction increases with increasing the order of multiplexing, namely the number of optical element channels. The proposed system is implemented by PDLC (Polymer Dispersed Liquid Crystal) mask which is operated by electric filed and generates optimal multiplexing patterns based on the Hadamard transform and single detector. It means that we obtain not only the each channel's optical power of multiple channel elements at once but also the best enhancement of SNR with single detector. Experimental results show that the proposed optical power meter is suitable for an active optical alignment system for multiple channel optical elements.