• Proceedings of the IEEK Conference
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• 2003.11a
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• pp.537-540
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• 2003

In this paper, we evaluated error correction performance and recording density of an optical disc system. The performance of Low-Density Parity Check code (LDPC) is compared to the HD-DVD (BD) ECC. The recording density of optical disc can be increased by reducing the redundancy of the user data. Moreover, since the correction capability of LDPC with decreased redundancy is better than that of BD, the recording density can also be increased by reducing the mark length of the data on the disc surface.

• Journal of the Korean Institute of Telematics and Electronics
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• v.23 no.6
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• pp.840-845
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• 1986

In this Part II of the paper, we evaluated the fabrication error and dividing characteristics for the opticalfilters proposed in the Part I. Furthermore, we propose an integrated optical filter with a new function that can eliminate the fabdrication error. The fabrication method and filtering characteristics have been tested by experiments, thereby confirming the validity of the design theory.

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.493-494
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• 2006

Fabrication-error tolerant directional couplers are designed and analyzed. In the wavelength region of $1.55{\mu}m$, the coupling characteristics of the 3dB coupler is 50${\pm}$4%, when the waveguide width error is ${\pm}0.2{\mu}m$.

• Proceedings of the IEEK Conference
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• 2000.06b
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• pp.262-265
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• 2000

This paper describes design of a (32, 28) Reed Solomon decoder for optical compact disk provides double error detecting and correcting capability. The most complex circuit in the RS decoder is part for solving the error location numbers from error location polynomial, and the circuit has great influence on overall decoder complexity. We use RAM based architecture with Euclid algorithm, Chien search algorithm and Forney algorithm. We have developed VHDL model and Performed logic synthesis using the SYNOPSYS CAD tool. Then, the RS decoder has been implemented with FPGA. The total umber of gate is about 11,000 gates and it operates at 20MHz.

• Journal of the Korean Society for Precision Engineering
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• v.29 no.8
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• pp.863-872
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• 2012

The squareness measurement of driving axes of a machine tool is very important to evaluate the performance of the machine. Laser interferometer measurement system is one of the most reliable equipment to measure the squareness. However, squareness measurement using laser system with an optical square result in restriction of straightness optics setup and Abbe's offset. This offset combines with angular errors during the motion of an axis to cause Abbe's error. In addition, the difficulty in optical square setup causes restriction of other optics and limitation of measurable range. In this paper, mathematical approaches are presented to eliminate the Abbe's error and to estimate squareness for full range by using the best fit of straightness data measured without an optical square. Experiments for squareness measurement of 3 axis machine tool were conducted and the proposed techniques were used for squareness evaluation with elimination of Abbe's error and squareness estimation for the full travel range.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.4
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• pp.1784-1788
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• 2012

In this paper we considered condition for keep standard error probability in optical transmission system that applied on-off keying transmission which are modulated amplitude along the signal. we calculated received sensitivity of receiver in on-off keying transmission for optical detector have quantum efficiency belong 1 in optical transmission system. For BT is over 30, the number of photon is belong 10000 for maintain standard error probability. also we considered Also, we install a preamplifier to the receiver for considering the low output may be used with a light that was able to get results.

• Proceedings of the Korean Society of Broadcast Engineers Conference
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• 2010.07a
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• pp.353-355
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• 2010

Optical flow 는 컴퓨터 비전에서 기본적이고 중요한 연구 분야 중에 하나이며 지금까지 많은 알고리즘이 제안되었다. 그러나 여전히 Optical flow의 많은 기법들은 텍스처가 없는 영역들과 이미지의 경계부분에서 정확한 결과를 얻는 데 많은 어려움을 갖고 있으며 이러한 Optical flow 의 성능을 평가하기 위해서 지금까지는 Endpoint Error 와 Angular Error 등과 같은 방법을 사용하고 있다. 이 논문에서는 유명한 optical flow 기법들을 초기 모델부터 최근 기법까지 간략하게 설명함으로써 optical flow 기법들이 어떻게 진행되어 왔는지 살펴보고 특히 occlusion 영역과 경계부분에서의 성능을 평가하였다.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.8
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• pp.1595-1604
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• 2009

An Optical disk driver is used in many electronic products besides the computers. In particular, the demands are recently increased as an optical disk player/recorder in the mobile products such as camcorder, portable player or in the home theater appliances, etc. However, the more the mobility is emphasized, the more the optical disk player is exposed to the disturbance inputs. For reducing the possibility of malfunction of the optical disk, we propose a nonlinear controller using the disturbance detecting algorithm based on the Kalman filter. Actual experiments were executed to verify the performance of the proposed method. The proposed method controls the tracking error signal within ${\pm}0.1{\mu}m$.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.11
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• pp.123-129
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• 2011

In terrestrial wireless optical communication links, atmospheric effects including turbulence, absorption and scattering have significant impact on the system performance. Based on the analysis of transmission in atmospheric channel concerning 830[nm] wavelength diode laser beam, performance of free space optical (FSO) link utilizing Galilean optics as a laser beam transmitting and receving optics, PIN photodiode as a detecting device. In this paper we designed optical link equation for received optical power and we analyze the atmospheric effects on the signal to noise ratio (SNR) and bit error rate (BER) of an terrestrial FSO system. We show that the possible communication distance for BER=$10^{-9}$ in proposed adverse atmospheric conditions.

• Journal of Astronomy and Space Sciences
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• v.36 no.3
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• pp.169-180
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• 2019

In this study, a batch least square estimator that utilizes optical observation data is developed and utilized to determine geostationary orbits (GEO). Through numerical simulations, the effects of error sources, such as clock errors, measurement noise, and the a priori state error, are analyzed. The actual optical tracking data of a GEO satellite, the Communication, Ocean and Meteorological Satellite (COMS), provided by the optical wide-field patrol network (OWL-Net) is used with the developed batch filter for orbit determination. The accuracy of the determined orbit is evaluated by comparison with two-line elements (TLE) and confirmed as proper for the continuous monitoring of GEO objects. Also, the measurement residuals are converged to several arcseconds, corresponding to the OWL-Net performance. Based on these analyses, it is verified that the independent operation of electro-optic space surveillance systems is possible, and the ephemerides of space objects can be obtained.