• ETRI Journal
• /
• v.27 no.3
• /
• pp.312-318
• /
• 2005

Mid-span spectral inversion (MSSI) has to utilize high optical pump power, for its operation principle is based on a nonlinear optical wavelength conversion. In this paper, a low pump-power operation of MSSI-based chromatic dispersion compensation (CDC) has been achieved successfully, for the first time to our knowledge, by introducing a noise pre-reduction scheme in cascaded wavelength conversions with periodically poled $LiNbO_3$ waveguides at a relatively low operation temperature. As preliminary studies, phase-matching properties and operation-temperature dependence of the wavelength converter (WC) were characterized. The WC pumped at 1549 nm exhibited a wide conversion bandwidth of 59 nm covering the entire C-band and a conversion efficiency of -23.6 dB at 11 dBm pump power. CDC experiments were implemented with 2.5 and 10 Gb/s transmission systems over 100 km single-mode fiber. Although it is well-known that the signal distortion due to chromatic dispersion is not critical at a 2.5 Gb/s transmission, the clear recovery of eye patterns was identified. At 10 Gb/s transmission experiments, eye patterns were retrieved distinctly from seriously distorted ones, and notable improvements in bit-error rates were acquired at a low pump power of 14 dBm.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
• /
• v.14 no.10
• /
• pp.1104-1111
• /
• 2003

The paper presents an algorithm for the compensation of gain and phase imbalances to exist between I-phase and Q-phase signal at direct conversion receiver. We propose a gain and phase imbalances blind equalization compensation algorithm by using variable step-size adaptive loop at direct conversion receiver. The blind equalization schemes have trade-off between convergence speed and jitter effect for the compensation of gain and phase imbalance. We propose the variable step-size adaptive loop method, which varies the loop coefficients according to errors, for recovering these problem. By using variable step-size adaptive loops, we propose to speed up the convergence process and reduce the jitter effect and simulation results show that the algorithm compensates signal loss and speeds up convergence time.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.40 no.5
• /
• pp.322-331
• /
• 2003

Advances of high-definition television(HDTV) and personal computers call for the mutual conversion between interlaced signal and progressive signal. Especially, deinterlacing which is known as an interlaced to progressive conversion has been recently required and investigated. In this paper, we propose new deinterlacing algorithm considering sub-pixel motion information. In order to reduce the error of motion estimation, we analyze the effect of inaccurate sub-pixel motion information and model it as zero-mean Gaussian noises added respectively to each low resolution image(field). The error caused by inaccurate motion information is reduced by determining regularization parameter according to the error of motion estimation in each channel. The validity of the proposed algorithm is demonstrated both theoretically and experimentally in this paper.

• Journal of the Institute of Convergence Signal Processing
• /
• v.3 no.2
• /
• pp.83-88
• /
• 2002

In this paper, a POS interfacing and temperature compensable LPG dispensing control system(LDCS) has been developed. A LDCS includes a 16-bit 80C196 microprocessor, RAM, ROM, video driver, and programmable peripheral devices. Based on gas flow encoding pulse, temperature-voltage conversion values and apparatus calibration values, the LDCS controls the LPG dispensing quantity with switching on or off the solenoid valves. The temperature compensation is performed with a 10-bit A/D conversion and its range is from +7$0^{\circ}C$ to -3$0^{\circ}C$ with a 0.5$^{\circ}C$ resolution.

• Korean Journal of Optics and Photonics
• /
• v.16 no.1
• /
• pp.27-33
• /
• 2005

In this paper, a new wavelength converter using an SOA(Semiconductor Optical Amplifier)-loop-mirror for NRZ(NonReturn to Zero) optical data has been proposed and experimentally demonstrated. Conventional nonlinear fiber-loop-mirror methods can perform RZ-to-RZ, NRZ-to-RZ, and RZ-to-NRZ data format conversion, but NRZ-to-NRZ conversion has not been demonstrated until now. The experiment for the conversion from a 1300 nm NRZ data signal at 1.5 Gbps to a 1550 nm NRZ data one is successfully performed using a fiber-loop-mirror with 1300 nm-SOA.

• Tribology and Lubricants
• /
• v.21 no.5
• /
• pp.221-226
• /
• 2005

A new calibration method for exact measurement of friction force in atomic force microscope (AFM) is presented. A new conversion factor involves a contact factor affected by tip, cantilever and contact stiffness. Especially the effect of contact stiffness on the conversion factor between lateral force and lateral signal is considered. Conventional conversion factor and a new modified conversion factor were experimentally compared. Results showed that a new calibration method could minimize the effect of normal load on friction force and improve the conventional method. A new method could be applied to the specimens with different physical properties.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.28 no.12
• /
• pp.1906-1913
• /
• 2004

A new method has been proposed for the calibration of frictional forces in atomic force microscopy. Angle conversion factor is defined using the relationship between torsional angle and frictional signal. Once the factor is obtained from a cantilever, it can be applied to other cantilevers without additional experiments. Moment balance equations on the flat surface and top edge of a commercial step grating are used to obtain angle conversion factor. Proposed method is verified through another step grating test and frictional behavior of Mica.

• Proceedings of the KSME Conference
• /
• 2004.11a
• /
• pp.846-851
• /
• 2004

A new method has been proposed for the calibration of frictional forces in atomic force microscopy. Angle conversion factor is defined using the relationship between torsional angle and frictional signal. Once the factor is obtained from a cantilever, it can be applied to other cantilevers without additional experiments. Moment balance equations on the flat surface and top edge of a commercial step grating are used to obtain angle conversion factor. Proposed method is verified through another step grating test and frictional behavior of Mica.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.58 no.8
• /
• pp.1544-1550
• /
• 2009

In this paper, a new single phase voltage sag/swell compensator using direct power conversion is proposed. A new compensator consists of input/output filter, series transformer and direct ac-ac converter, which is a single-phase back-to-back PWM converter without dc-link capacitors. Advantages of the proposed compensator include: simple power circuit by eliminating dc link electrolytic capacitors and thereby, improved reliability and increased life time of the entire compensator; simple PWM strategy or compensating voltage sag/swell at the same time and reduced switching losses in the ac-ac converter. Further, the proposed scheme is able to adopt simple switch commutation method without requiring complex four-step commutation method that is commonly employed in the direct power conversion. Simulation and experimental results are shown to demonstrate the advantages of the new compensator and PWM strategy. A 220V, 3kVA single-phase compensator based on the digital signal processor controller is built and tested.

• MALSORI
• /
• no.45
• /
• pp.63-77
• /
• 2003

The purpose of voice color conversion is to change the speaker identity perceived from the speech signal. In this paper, we propose a new voice color conversion algorithm through the formant shifting and the spectrum-tilt modification in the frequency domain. The basic idea of this technique is to convert the positions of source formants into those of target speaker's formants through interpolation and decimation and to modify the spectrum-tilt by utilizing the information of both speakers' spectrum envelops. The LPC spectrum is adopted to evaluate the position of formant and the information of spectrum-tilt. Our algorithm enables us to convert the speaker identity rather successfully while maintaining good speech quality, since it modifies speech waveforms directly in the frequency domain.