• Journal of the Korean Institute of Telematics and Electronics D
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• v.36D no.8
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• pp.79-86
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• 1999

A simulation of 10 Gbps optical fiber transmission system using DCf(dispersion compensating fiber) for the dispersion compensation is performed. In order to analyze the NRZ pulse propagation in nonlinear, dispersive and lossy fiber, the split-step finite element method that is combination of finite element method and finite difference method is used. Also, we obtained the optical eye diagram and BER characteristics at the receiver of the system that is contained the optical amplifier and system noises. As a result of simulation, we obtain that the dispersion penalty is about 0.8dB after 50km transmission and the receiver sensitivities at $10^{-9}$ BER are -27.4dBm with EDFA pre-amplifier of 12dB gain and -15.6dBm without EDFA.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.698-701
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• 2007

DAHAN, the first 1 MWe Solar Power Tower system locates north to Beijing where nearby The Great Wall is now under construction with cooperation between China and Korea. Results in predicting the preliminary performance of this central receiver system are presented in this paper. Operating cycles under some typical weather condition days are simulated and commented. These results can be used to assess the impact of alternative plant designs or operating strategies on annual energy production, with the final objective being to optimize the design of central receiver power plants. Two subsystems are considered in the system simulation: the solar field and the power block. Mathematic models are used to represent physical phenomena and relationships so that the characteristics of physical processes involving these phenomena can be predicted. Decisions regarding the best position for locating heliostats relative to the receiver and how high to place the receiver above the field constitute a multifaceted problem. Four different kinds of field layout are designed and analyzed by the use of ray tracing and mathematical simulation techniques to determine the overall optical performance ${\eta}_{field}$ and the spillage ${\eta}_{spill}$.The power block including a Rankine cycle is analyzed by conventional energy balance methods.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.4
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• pp.9-14
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• 2003

The new optical link receiver with data transfer rate higher than 10Mbps at the supply voltage of 1.8V was designed and fabricated using bipolar technology. The fabricated IC showed the dissipation current of 4.6mA under high level input voltage of 1.5V. The high level output voltage($V_{OH}$) and the low level output voltage($V_{OL}$) were 1.15V and 0V, respectively, for a given 10 Mbps signal which has duty ratio of 50%, $V_{IL}$(low level input voltage) of 0.5V, and $V_{IH}$(high level input voltage) of 1.5V, The duty ratio of output waveform was 52.6%. The rising time(t$_{r}$) and the falling time(t$_{f}$) were 9.5ns and 6.8ns, respectively. The propagation delay difference($t_{PHC}-t_{PLH}$) and the jitter($t_j$) were 11.7ns and 4.3ns, respectively.y.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.36C no.4
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• pp.45-53
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• 1999

A pre amplifier, a limiting amplifier, and a decision IC chipset for 10Gbit/s optical receiver was implemented with AIGaAs/GaAs HBT(Heterojunction Bipolar Transistor) technology. The HBT allows a cutoff frequency of 55GHz and a maximum oscillation of 45GHz. An optical receiver front-end was implemented with the fabricated pre amplifier IC and a PIN photodiode. It showed 46dB$\Omega$, gain and $f_{3db}$ of 12.3GHz. The limiting amplifier Ie showed 27dB small signal gain, $f_{3db}$ of 1O.6GHz, and the output is limited to 900mVp-p from 20mVp-p input voltage. The decision circuit IC showed 300-degree phase margin and input voltage sensitivity of 47mVp-p at 1OGbit/s.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.63 no.12
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• pp.1697-1703
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• 2014

In this paper, we propose an indoor RSSI (received signal strength indication)-based localization method that uses virtually overlapped visible light with an indoor LED lighting system. In our system, a photodiode (PD) measures the RSSI from LED lamps that blink in one row or column units. Subsequently, the RSSI is used to obtain the horizontal distances between the LED lamps and the receiver with the predetermined characteristics curve, R-D curve, that represents the relation between the RSSI and the horizontal distances. When the controlled LED lamps blink in one row or column units, the R-D curve at the border of the LED lamps is different because of the weak lighting, which results in the position sensing error of the receiver. The deviation of the optical power of each LED also causes the error. To solve these problems, we propose a method that overlaps the visible light through the numerical operation at the receiver side without any modification of the light source side. Our proposed method has been simulated in a room measuring $1.2{\times}1.2{\times}1.8m^3$ considering the effect of the error on the optical power of the LED. The simulation result shows that the proposed method eliminates the error condition with the R-D curve and achieves an average positioning error of 13.4 mm under the error rate 3% of the optical power.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.2
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• pp.134-139
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• 2004

A clock recovery circuit for a 40 Gb/s optical receiver has been designed and implemented. The clock recovery circuit consists of pre-amplifiers, a nonlinear circuit with diodes, a bandpass filter and a clock amplifier. Before implementing the 40 Gb/s clock recovery circuit, a 10 Gb/s clock recovery circuit has been successfully implemented and tested. With the 40 Gb/s clock recovery circuit, when a 40 Gb/s signal of -10 dBm was applied to the input of the circuit, the 40 GHz clock was recovered with the -20 dBm output power after passing through the nonlinear circuit. The output signal from the nonlinear circuit passes through a narrow-band filter, and then amplified. The implemented clock recovery circuit is planned to be used for the input of a phase locked loop to further stabilize the recovered clock signal and to reduce the clock jitter.

• Current Optics and Photonics
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• v.2 no.2
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• pp.195-202
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• 2018

A Scanning Rayleigh Doppler lidar for wind profiling based on a non-polarized beam splitter cube optically contacted FPI is developed for wind measurement from high troposphere to low stratosphere in 5-35 km. Non-polarized beam splitter cube optically contacted to the FPI are used for a stable optical receiver. Zero Doppler shift correction is used to correct for laser or FPI frequency jitter and drift and the timing sequence is designed. Stability of the receiver for Doppler shift discrimination is validated by measuring the transmissions of FPI in different days and analyzed the response functions. The maximal relative wind deviation due to the stability of the optical receiver is about 4.1% and the standard deviation of wind velocity is 1.6% due to the stability. Wind measurement comparison experiments were carried out in Jiuquan ($39.741^{\circ}N$, $98.495^{\circ}E$), Gansu province of China in 2015, showing good agreement with radiosonde result data. Continuous wind field observation was performed from October 16th to November 12th and semi-continuous wind field of 19 nights are presented.

• Journal of the Korean Institute of Telematics and Electronics
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• v.27 no.10
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• pp.154-160
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• 1990

System modeling for Heterodyne/Coherent Optical BFSK receiver is described and its receiver performance is evaluated. Receiver performance is deteriorated due to both shot noise and laser phase nois. Therefore, to minimize these noise impacts PLL loop natural frequency is selected optimally. For different power penalty due to phase error, required phase error variance to achieve $BER=10^{-9}$, nomalized loop power, and laser linewidth/bit rate(${\Delta\nu}s/Rb$) are derived. For 0.5dB power penalty, phase error variance=0.035(${rad^2}$), photon numbers=20.0, nomalized loop power = $3.8{\times}10^{-3}$(electron/s per herz), and ${\Delta\nu}s/Rb=5.24{\times}10^{-3}$ are obtained.

• ETRI Journal
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• v.38 no.5
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• pp.981-987
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• 2016

We present a cost-effective dual polarization quadrature phase-shift coherent receiver module using a silica planar lightwave circuit (PLC) hybrid assembly. Two polarization beam splitters and two $90^{\circ}$ optical hybrids are monolithically integrated in one silica PLC chip with an index contrast of $2%-{\Delta}$. Two four-channel spot-size converter integrated waveguide-photodetector (PD) arrays are bonded on PD carriers for transverse-electric/transverse-magnetic polarization, and butt-coupled to a polished facet of the PLC using a simple chip-to-chip bonding method. Instead of a ceramic sub-mount, a low-cost printed circuit board is applied in the module. A stepped CuW block is used to dissipate the heat generated from trans-impedance amplifiers and to vertically align RF transmission lines. The fabricated coherent receiver shows a 3-dB bandwidth of 26 GHz and a common mode rejection ratio of 16 dB at 22 GHz for a local oscillator optical input. A bit error rate of $8.3{\times}10^{-11}$ is achieved at a 112-Gbps back-to-back transmission with off-line digital signal processing.

• Proceedings of the IEEK Conference
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• 2002.07b
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• pp.1109-1112
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• 2002

A non-coherent synchronous all-optical code-division multiple-access (CDMA) network is proposed. In this network, symmetric codes derived from prime sequence codes are used. We present the construction of symmetric codes and show that the pseudo-orthogonality of the new codes is the same as that of the original prime-sequence codes while the cardinality of the new codes is larger than that of the prime sequence codes and the modified prime codes in the same field GF(p). Therefore, an optical CDMA LAN using symmetric codes can have a larger number of potential subscribers. The new codes allow designing fully programmable serial all-optical transmitter and receiver suitable for low-loss, high-capacity, optical CDMA LANs. It is also shown that compared to systems using modified prime codes the proposed system can achieve better BER performance for low received chip optical power.