• 제어로봇시스템학회논문지
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• 제13권1호
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• pp.58-64
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• 2007

In this paper, the stabilization problem of the image stabilization system(ISS) that captures the image of an object on the ground by remote sensing is considered. The ISS should be stable under outer disturbance such as helicopter vibration for tracking line of sight. Although PID controllers are optimized for the system, disturbances cause the instability of the system. To minimize the effect of the disturbance, the time-delayed control method is used to compensate for uncertainties. Simulation studies are performed and experiments are conducted to confirm the simulation results. Performances of PID control and time-delayed control methods are compared.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 심포지엄 논문집 정보 및 제어부문
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• pp.430-432
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• 2007

This paper proposes the possibility of SonicID system which is the active RFID based on the ultrasonic spectrum instead of using radio frequency. For the feasibility study, various performance indexes are measured in terms of power consumption and signal path loss onto the frequencies of 40KHz, 433MHz, and 2.4GHz. In addition to the line of sight condition, realistic situations are considered for diverse deploying environments. The results of these analyses demonstrate that the SonicID holds the potential to meet the needs of future advanced RFID system in a scalable fashion.

• 한국자동차공학회논문집
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• 제15권4호
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• pp.27-32
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• 2007

Head-Up Display system makes it possible for the driver to be informed of important vehicle data such as vehicle speed, engine RPM or navigation data without taking the driver's eyes off the road. Long focal length optics, LCD with bright illumination, image generator and vehicle interface controllers are key parts of head-up display system. All these parts have been designed, developed and applied to the test vehicle. Virtual images are located about 2m ahead of the driver's eye by projecting it onto the windshield just below the driver's line of sight. Developed head-up display system shows satisfactory results for future commercialization.

• ETRI Journal
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• 제23권3호
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• pp.121-128
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• 2001

In this paper, the theoretical as well as experimental results of BER characteristics of three different modulation schemes, ASK, FSK and BPSK, in a multi-path Rician channel are addressed. These BER characteristics are analyzed as a function of $E_b/N_o$ and the power ratio of the line of sight (LOS) component to the Rayleigh scattered component. The theoretical as well as computer simulation results shows the ASK is the most suitable modulation scheme for the dedicated short range communication (DSRC) in terms of implemental cost and system complexity. The decision feedback equalizer is proved to be very effective in canceling the multi-path interference in the DSRC channel environment. The simulation result of the equalized ASK, reveals the performance enhancement achievable with decision feedback (DFE) equalizer for the first generation DSRC system. The multi-ray DSRC channel model is also provided to predict the received carrier power and fluctuation, which are quite dependent on the surroundings of a cell.

• 천문학회보
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• 제39권1호
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• pp.42.1-42.1
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• 2014

A gravitational weak-lensing map provides a weighted "picture" of the projected surface mass density and is to be an important tool for identifying "mass-selected" clusters of galaxies. However, weak-lensing maps have a limitation due to the projection of large-sclae structure along the line-of-sight. Geller et al. (2010) and Kurtz et al. (2012) compared massive clusters identified in a dense redshift survey with significant weak-lensing map convergence peaks. Both assessments of the efficiency of weak-lensing map for cluster identification did not draw a general conclusion, because the sample is so small. Thus, we additionally perform deep imaging observations of fields in a dense galaxy redshift survey that contain galaxy clusters at z~0.2-0.5, using CFHT Megacam. Our study will provide an important opportunity to examine the efficiency and completeness of a weak-lensing selection, and further to improve the method of cluster identification in future weak-lensing surveys.

• 제어로봇시스템학회논문지
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• 제16권2호
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• pp.177-187
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• 2010

A MTG (Multimode Tracking and Guidance) system is employed to compensate for the limitations of individual seekers such as RF (Radio frequency) or IIR (Imaging Infra-red) and to improve the overall tracking and guidance performance in jamming, clutter, and adverse weather environments. In the MTG system, tracking filter, data association, and data fusion methods are important elements to maximize the effectiveness of precision homing missile guidance. This paper proposes the formulation of a Kalman filter for the estimation of line-of-sight rate from seeker measurements in missiles guided by proportional navigation. Also, we suggest the HPDA (Highest Probability Data Association) and data fusion methods of the MTG system for target tracking in the adverse environments. Mont-Carlo simulation is employed to evaluate the overall tracking performance and guidance accuracy.

• 대한전자공학회논문지TE
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• 제39권2호
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• pp.104-109
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• 2002

본 논문에서는 전파경로를 구할 수 있는 모델을 제안하였다. 이 모델은 가시거리영역에서 마지막으로 이루어지는 반사위치를 입사각의 변화에 따라 다르게 구하였고. 도심지역의 다양한 형태를 고려하기 위해 도로폭과 교차각을 각각 변화시켰다. 그 결과 전파경로는 교차각이 15$^{\circ}$~75$^{\circ}$로 변화함에 따라 증가하였으며 기존모델 보다 대략 1[dB]~2[dB]정도 감쇄됨을 알 수 있었다.

• Journal of Communications and Networks
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• 제14권5호
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• pp.518-523
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• 2012

This paper presents new coherent and non-coherent detection methods for the IEEE 802.15.4a low-rate ultra-wideband physical layer with forward error correction (FEC) coding techniques. The coherent detection method involving channel estimation is based on the correlation characteristics of the preamble signal. A coherent receiver uses novel iterated selective-rake (IT-SRAKE) to detect 2-bit data in a non-line-of-sight channel. The non-coherent detection method that does not involve channel estimation employs a 2-bit data detection scheme using modified transmitted reference pulse cluster (M-TRPC) methods. To compare the two schemes, we have designed an IT-SRAKE receiver and a MTRPC receiver using an IEEE 802.15.4a physical layer. Simulation results show the performance of IT-SRAKE is better than that of the M-TRPC by 3-9 dB.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1996년도 하계학술대회 논문집 B
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• pp.946-948
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• 1996

In this paper, we consider a 2-dimensional pursuit-evasion game between a maneuvering target and a coasting missile using qualitative game theory. The optimal evasion algorithm of the target and the optimal guidance algorithm of the missile are determined and the barrier trajectories of this game are obtained through computer simulation. The optimal strategy of the missile and target is to turn toward the final line of sight direction using maximum input and maintain its direction. The capture set of the missile can be obtained by backward integration from the BUP.

• Journal of Astronomy and Space Sciences
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• 제4권1호
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• pp.35-45
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• 1987

The peculiar elliptical (EOp) galaxy NGC 4486 and two KOII comparison stars HR5450, HR6935 were observed spectroscopically using the 74-inch telescope and Image Tube at Mt. Stomlo Observatory. From the Gaussian Broadening Function, broadened spectrum of two comparison stars were computed for the range between wavelength 4800$\AA$ and 5400$\AA$. Velocity dispersions in the line of sight of M87 were obtained by visual fitting. The fitted velocity dispersion is 450 km/sec at the nucleus, 350km/sec at r=12", and 300km/sec at r=24". Using the photometric data and the central value of velocity dispersion, we determined the mass of M87. From <$r^{2/4}$ law and the Virial theorem the calculated total mass in $2.1\times10^{12}M_\odot$ and from the King Model $M=1.2\times10^{12}M_\odot$. And M/L ratio of M87 is about 30.