• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.41 no.9
• /
• pp.39-48
• /
• 2004

Turbo codes, whose performance in bit error rate is close to the Shannon limit, have been adopted as a part of standard for the third-generation high-speed wireless data services. Iterative Turbo decoding results in decoding delay and high power consumption. As wireless communication systems can only use limited power supply, low power design techniques are essential for mobile device implementation. This paper proposes new effective criteria for stopping the iteration process in turbo decoding to reduce power consumption. By setting two stopping criteria, decodable threshold and undecodable threshold, we can effectively reduce the number of decoding iterations with only negligible error-correcting performance degradation. Simulation results show that the number of unsuccessful error-correction can be reduced by 89% and the number of decoding iterations can be reduced by 29% on the average among 12500 simulations when compared with those of an existing typical method.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.43 no.12
• /
• pp.1035-1047
• /
• 2015

Wind tunnel experiment and computational analysis have been carried out to evaluate the performance of propeller for scale electric-powered HALE UAV, named EAV-2H+. Performance curves are measured for three propellers and their adequacy for EAV-2H+ installation is examined through consideration of operating conditions. Decline in performance coefficients is observed in low rpm region. Also, the effect of transition tape on propeller performance is measured and analyzed. The computational performance analyses are carried out by using commercial CFD program. The thrust and power coefficient from computations show good agreement with experimental results. Performance coefficients are compared and the influence of measurement device which contributes to discrepancy of the results is examined. Transition SST model is confirmed to yield the tendency of performance decline in low rpm range, similar to experimental observation. The decrease in aerodynamic performance of blade element due to low Reynolds number is identified to cause the decline in propeller performance. Analyses for high altitude conditions confirms degradation in propeller performance.

• Journal of the Institute of Electronics Engineers of Korea SP
• /
• v.38 no.5
• /
• pp.529-537
• /
• 2001

According to increase of preference to the large display device, demand of a three-tube projection TV increase in the display market. But luminance per unit area of a 3-tube projection TV is less bright than that of original one -tube TV The color gamut of phosphor used in the projection TV is different to standard gamut of phosphor in NTSC. In this paper, we analyze the relationship between coordinates of RGB phosphor and RGB beam currents according to the color temperature in projection HDTV. We also proposed the range of reference white which maximize the luminance that viewer feel based on both Helmholtz-Kohlrausch effect which is visual property and degradation of image according to the change of beam profile by current-ratio.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.38 no.11
• /
• pp.765-770
• /
• 2001

Metal-ferroelectric-insulator- semiconductor(MFTS) devices by using rapid thermal annealed (RTA) LiNbO$_3$/AIN/Si(100) structures were successfully fabricated and demonstrated nonvolatile memory operations. Metal-insulator-semiconductor(MIS) C-V properties with high dielectric AIN thin films showed no hysteresis and good interface properties. The dielectric constant of the AIN film calculated from the capacitance at the accumulation region in the capacitance-voltage(C-V) characteristics was about 8. The C-V characteristics of MFIS capacitor showed a hysteresis loop due to the ferroelectric nature of the LiNbO$_3$ thin films. Typical dielectric constant value of LiNbO$_3$ film of MFIS device was about 23. The memory window width was about 1.2 V at the gate voltage of $\pm$5 V ranges. Typical gate leakage current density of the MFIS structure was the order of 10$^{-9}$ A/$\textrm{cm}^2$ at the range of within $\pm$500 kV/cm. The ferroelectric capacitors showed no polarization degradation up to about 10$^{11}$ switching cycles when subjected to symmetric bipolar voltage pulse(peak-to-peak 8 V, 50 % duty cycle) in the 500 kHz.

• Journal of the Institute of Electronics Engineers of Korea SD
• /
• v.38 no.5
• /
• pp.347-356
• /
• 2001

The issues that influence the packaging of high-speed LiNbO$_{3}$ modulators are discussed, and packaging approaches that result in only minor degradation of the modulator's RF performance are described. The primary problems dealt in this paper, associated with high-speed device packaging, are fallen into the following five categories: die features, pigtailing, suppression of RF package resonance, RF launcher approach, termination approach. By considering factors to influence the modulator performance in packaging, a LiNbO$_{3}$ intensity modulator was fabricated and packaged to have S21 better than -3㏈ upto 10㎓ and S11 below -l5㏈ upto 18㎓.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.38 no.9
• /
• pp.882-889
• /
• 2010

Semi-active vibration control is one of the attractive control methods for space application due to its robustness as passive damping system and much higher damping performance than passive system. However, a chattering induced by the sudden variation of damping force at the time of On-Off switching of semi-active control device degrades pointing performance of the on-board payload. In this paper, to enhance the pointing performance of the on-board payload, we proposed a semi-active vibration isolation with a strategy for attenuating chattering effect. Numerical simulation results using simplified analysis model indicated that the proposed semi-active control strategy produced much better isolation performance than the conventional Bang-Bang control semi-active control laws derived from skyhook and LQ theories.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.24 no.6B
• /
• pp.1156-1164
• /
• 1999

In this paper, we have studied the 8 YSB (8 Vestigial Side Band) method which is decided as the standard of modulators for next generation digital TV System. In developing digital TV System, one of the difficult problems is how digital signal can be transmitted to the receiver without any phase distortion. But, phase error is liable to occur by imperfect design, circumstance variation and device degradation. These characteristics result in distortion of 1,0 signal of modulator and interference in adjacent channels. In particular, the interference in modulator of a high power amplifier result in serious problems in adjacent channels. Here we analyzed problems of phase error which are occurred when 8 levels digital signals are modulated to If signal. And we suggested phase error compensation algorithm and discussed the results for adaptation of the algorithm

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
• /
• v.31 no.3
• /
• pp.141-145
• /
• 2018

Ni-InGaAs shows promise as a self-aligned S/D (source/drain) alloy for n-InGaAs MOSFETs (metal-oxide-semiconductor field-effect transistors). However, limited thermal stability and instability of the microstructural morphology of Ni-InGaAs could limit the device performance. The in situ deposition of a Pd interlayer beneath the Ni layer was proposed as a strategy to improve the thermal stability of Ni-InGaAs. The Ni-InGaAs alloy layer prepared with the Pd interlayer showed better surface roughness and thermal stability after furnace annealing at $570^{\circ}C$ for 30 min, while the Ni-InGaAs without the Pd interlayer showed degradation above $500^{\circ}C$. The Pd/Ni/TiN structure offers a promising route to thermally immune Ni-InGaAs with applications in future n-InGaAs MOSFET technologies.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.15 no.7
• /
• pp.1537-1542
• /
• 2011

In this paper, the subthreshold characteristics have been analyzed for various oxide thickness of double gate MOSFET(DGMOSFET) using Poisson's equation with nonuniform doping distribution. The DGMOSFET is extensively been studying since it can shrink the short channel effects(SCEs) in nano device. The degradation of subthreshold swing(SS) known as SCEs has been presented using analytical for, of Poisson's equation with nonuniform doping distribution for DGMOSFET. The SS have been analyzed for, change of gate oxide thickness to be the most important structural parameters of DGMOSFET. To verify this potential and transport models of thus analytical Poisson's equation, the results have been compared with those of the numerical Poisson's equation, and subthreshold swing has been analyzed using this models for DGMOSFET.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.36 no.1
• /
• pp.169-180
• /
• 2016

The spaces of port and urban in a Port City have different space characteristics substantially, but those are required to be developed interdependently. Degradation and loss of the sense of place in the existing spaces caused by decline of natural function have an adverse effect on the revival of local economy as well as make worse image of the entire city. In some developed countries, therefore, many researches on the port spaces lagging behind the times due to changes of the characteristics and function of port spaces have been conducted continuously for a long time. This study aims at seeking a device how the domestic hinterland could be utilized as efficient spaces having the characteristics of outskirts space and port city interface through the application of characteristics of the interface space of port city, capable of playing a role as buffer zone between the port space and the city space.