• Korean Journal of Cognitive Science
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• v.22 no.2
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• pp.173-192
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• 2011

The visual system applies previously learned contextual knowledge to facilitate the perception and encoding of scenes. When extrapolation following the employment of contextual information occurs, it sometimes leads to scene memory distortion: people report as if they saw more than they actually had seen. This phenomenon is called the "boundary extension" effect (Intraub & Richardson, 1989). The present study aimed to clarify the effects of contextual information on boundary extension in a more systematic way. Based on the assumption that it is harder to extract contextual information from inverted scenes compared to intact scenes, we presented inverted scenes either during encoding or retrieval to manipulate the level of contextual information and compared the magnitude of boundary extension effect for upright versus inverted scenes. In a series of experiments, we found that scene inversion during encoding, but not during retrieval, significantly reduced boundary extension. Showing reduced memory distortion for inverted scenes, the current study directly demonstrated that access to contextual information is a critical component of scene extrapolation process.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.31 no.2
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• pp.190-198
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• 1995

Many industrial servo amplifiers employ power transister as output device. Thyristor converters are not adopted to drive servo motor, although thyristor is superior to power TR in power rating, noise immunity, price, and size. The reason is, thyristor has no ability of self turn - off. Here in this paper line commutation, in which thyristor is turned off naturally since cathode voltage is higher than anode as time goes by, is employed to turn on thyristor with a delicate sequence. We developed thyristor servo amplifier which does not cause any damage on thyristor because it is designed to prevent triggering the two SCRs in the same arm simultaneously. And it was made clearly how to trigger SCR without any power line shorting and also harmonic analysis is carried out with the aid of FFT analyzer and proved that it can be used even severe reactive load. The designed circuit operated as a good DC amplifier in conventinal servomotor and the results can be use as a position control system application.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.10
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• pp.875-883
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• 2007

The objective of this research was to develop a coaxial rotor MAV which is suitable for a indoor reconnaissance mission. Preliminary design parameters were determined, based on the dimensions of other reference MAVs. The designed rotor performance was estimated by Blade Element Momentum Theory, and the analyses were compared against the measurements. Stability and vibration issues of the prototype were circumvented by making parts of vehicle with NC machine, as well as equipped with teetering rotor and stabilizer. The designed coaxial rotor MAV showed successfully flight equipped with video camera. However, it was founded that further research activities should be focused on efficient rotor design to obtain better performance.

• Journal of the Korean Magnetics Society
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• v.4 no.3
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• pp.256-262
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• 1994

$200{\AA}$ thick Co/Pd multilayered thin films were fabricated by sputtering. Two thicknesses of cobalt sublayer, $2{\AA}$ and $4{\AA}$ were chosen and the effects of sputtering pressure on the perpendicular magnetic anisotropy were investigated. It has been found that the optimum pressure for maximum perpendicular magnetic anisotropy(PMA) existed and the pressure for maximum PMA was lower for the multilayer with $2{\AA}$ cobalt layer than that with $4{\AA}$ cobalt thickness. As the sputtering gas presssure increased, domain wall motion with magnetization became difficult and the predominant mode of magnetization reversal changed from domain wall motion to magnetic moment rotation. It turned out that the perpendicular magnetic anisotropy was higher in case of $2{\AA}$ cobalt thickness than $4{\AA}$ cobait thickness.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2009.10a
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• pp.127-131
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• 2009

본 논문에서는 디지털 통신에서 비트 전송율을 향상 시킬 수 있는 웨이브릿 편이 변조 시스템을 제안한다. 기존의 웨이브릿 편이 변조 시스템에서는 스케일링 함수(scaling function)를 1로, 웨이브릿(wavelet)을 0으로 할당하여 0과 1을 구분하였다. 제안한 방식은 스케일링 함수와 웨이브릿 그리고 이 두 신호를 반전시킨 4개의 반송파를 사용하여 변조한다. 즉, 웨이브릿은 00, 반전된 웨이브릿은 01, 스케일링 함수를 10, 반전된 스케일링 함수를 11로 할당하여 비트 전송률을 2배로 향상시키고자 한다. 복조시에는 4개의 상관기를 이용하여 원래의 2진 데이터(2비트)를 복원하였다. 모의실험 결과 제안한 방식이 기존의 웨이브릿 편이 변조 시스템에 비해 전송효율이 2배 향상되었음을 알 수 있다.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.44 no.3 s.357
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• pp.20-25
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• 2007

The periodic domain-inversion in the selective areas of $Ti:LiNbO_3$ Mach-Zender waveguides was performed and band-pass modulators and single sideband (SSB) modulators were fabricated by using domain-reversal. The domain wall velocity was precisely controlled by real-time analysis of a poling-induced response current under an applied voltage. The domain wall velocity was significantly affected by the crystal orientation of the domain wall propagation which influenced the final domain geometry. In a certain case, the decomposition of $LiNbO_3$ crystal was observed, for example, under the condition of too fast domain wall propagation. The fabricated band-pass modulator with a periodic domain-inversion structure showed the maximum modulation efficiency at 30.3 GHz with 5.1 GHz 3dB-bandwidth, and SSB modulator was measured to show 33 dB USB suppression over LSB at 5.8 GHz RF.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.10
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• pp.76-81
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• 2013

A new phase frequency detector based digital phase-locked loop (PLL) of 125 MHz was designed using the 130 nm CMOS technology library consisting of inverting edge detectors along with a typical digital phase-locked loop to reduce the lock time and jitter for mid-frequency applications. XOR based inverting edge detectors were used to obtain a transition earlier than the reference signal to change the output more quickly. The HSPICE simulator was used in a Cadence environment for simulation. The performance of the digital phase-locked loops with the proposed phase frequency detector was compared with that of conventional phase frequency detector. The PLL with the proposed detector took $0.304{\mu}s$ to lock with a maximum jitter of approximately 0.1142 ns, whereas the conventional PLL took a minimum of $2.144{\mu}s$ to lock with a maximum jitter of approximately 0.1245 ns.

• Proceedings of the Optical Society of Korea Conference
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• 2005.07a
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• pp.102-103
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• 2005

• Proceedings of the Optical Society of Korea Conference
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• 2004.02a
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• pp.326-327
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• 2004

• Proceedings of the Optical Society of Korea Conference
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• 2006.07a
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• pp.121-122
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• 2006