• Journal of IKEEE
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• v.2 no.2 s.3
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• pp.194-199
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• 1998

In the atmospheric wireless optical communication system, the low power transmission can be accomplished by the high directivity of laser beam. But, the transmitted optical signal undergoes the serious influences by the atmospheric effects like absorption, scattering, and turbulence because the transmission channel is the atmospheric space. In this paper, therefore, we obtain the link equation for an atmospheric wireless optical LOS communication link under the atmospheric effects and find the repeaterless transmission length to estimate the system performance through the computer simulation. From the results of the computer simulation, we present the transmission length that is possible to transmit without a repeater at given data rates and know that data rate is decreased rapidly when the transmission length is increased slightly at given bit error rate.

• Journal of Broadcast Engineering
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• v.15 no.1
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• pp.99-111
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• 2010

In this paper as a follow-up to Paper I, the required fade margin derived in Paper I to preserve the same service quality has been examined by analyzing system and propagation characteristics as well as measured data. The comparison of the fade margin between simulated and measured results is also performed for the actual operating line-of-sight(LOS) and non-LOS links, and practical usefulness as an analysis tool is revealed by checking service quality of M/W system relevant to frequency reallocation. According to simulated and measured results, there was a little difference for LOS link between Mt. Moodung and Mt. Mangun, but a fairly good agreement was reached for non-LOS link between Andong KBS and transmitter site.

• Journal of The Korean Astronomical Society
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• v.54 no.2
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• pp.49-60
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• 2021

Observations of line of sight (LOS) Doppler velocity and non-thermal line width in the off-limb solar corona are often used for investigating the Alfvén wave signatures in the corona. In this study, we compare LOS Doppler velocities and non-thermal line widths obtained simultaneously from two different instruments, Coronal Multichannel Polarimeter (CoMP) and Hinode/EUV Imaging Spectrometer (EIS), on various off-limb coronal regions: flaring and quiescent active regions, equatorial quiet region, and polar prominence and plume regions observed in 2012-2014. CoMP provides the polarization at the Fe xiii 10747 Å coronal forbidden lines which allows their spectral line intensity, LOS Doppler velocity, and line width to be measured with a low spectral resolution of 1.2 Å in 2-D off limb corona between 1.05 and 1.40 RSun, while Hinode/EIS gives us the EUV spectral information with a high spectral resolution (0.025 Å) in a limited field of view raster scan. In order to compare them, we make pseudo raster scan CoMP maps using information of each EIS scan slit time and position. We compare the CoMP and EIS spectroscopic maps by visual inspection, and examine their pixel to pixel correlations and percentages of pixel numbers satisfying the condition that the differences between CoMP and EIS spectroscopic quantities are within the EIS measurement accuracy: ±3 km s-1 for LOS Doppler velocity and ±9 km s-1 for non-thermal width. The main results are summarized as follows. By comparing CoMP and EIS Doppler velocity distributions, we find that they are consistent with each other overall in the active regions and equatorial quiet region (0.25 ≤ CC ≤ 0.7), while they are partially similar to each other in the overlying loops of prominences and near the bottom of the polar plume (0.02 ≤ CC ≤ 0.18). CoMP Doppler velocities are consistent with the EIS ones within the EIS measurement accuracy in most regions (≥ 87% of pixels) except for the polar region (45% of pixels). We find that CoMP and EIS non-thermal width distributions are similar overall in the active regions (0.06 ≤ CC ≤ 0.61), while they seem to be different in the others (-0.1 ≤ CC ≤ 0.00). CoMP non-thermal widths are similar to EIS ones within the EIS measurement accuracy in a quiescent active region (79% of pixels), while they do not match in the other regions (≤ 61% of pixels); the CoMP observations tend to underestimate the widths by about 20% to 40% compared to the EIS ones. Our results demonstrate that CoMP observations can provide reliable 2-D LOS Doppler velocity distributions on active regions and might provide their non-thermal width distributions.

• International journal of advanced smart convergence
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• v.12 no.1
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• pp.31-40
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• 2023

This asymed drone controller is indispensable for two components: Guidance and Controller. In which the Ministry of Guidance will receive waypoints from which to form an orbit then combine the data with the current location of the vessel, thereby calculating and also supplying the controller to drive the vehicle to follow the outlined trajectory. This article will use the Line Of Sight (LOS) algorithm to design the Guidance and Controller sets. The result as well as the effectiveness of the controller will be shown through matlab/SIMULINK simulation.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.141.2-141
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• 2001

An approximate target adaptive guidance algorithm(TAG) is proposed on the basis of the assumption that angular acceleration of missile to target line-of-sight and start time for TAG can be obtained by IR seeker. The algorithm does not use any target state estimator. Instead, it avoids the problem of determining target attitude by using the observation that the missile using LOS rate guidance is nearly on the collision course in the later point of engagement. Computer simulation results show that the proposed algorithm can effectively perform target adaptive guidance.

• Proceedings of the Optical Society of Korea Conference
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• 2002.11a
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• pp.56-57
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• 2002

Wireless LAN(Local Access Network) 및 근거리 광대역 무선통신 등에 응용되어질 수 있는 근거리 무선 광통신을 저렴하고 소형의 모듈로 구현하였다. 100 Mb/s의 속도로 2-3m 거리에서 송 .수신 각도는 5-6$^{\circ}$로 LOS(Line Of Sight) 문제를 보상하여 동작 되도록 연구하였다 연구 결과를 모듈로 제작하여 인터넷 및 실시간 동영상 송.수신 실험을 수행하였다.

• International Journal of Aeronautical and Space Sciences
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• v.18 no.4
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• pp.697-708
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• 2017

The complex battlefield environment makes it difficult to intercept maneuvering targets for guided missiles. In this paper, a finite-time convergent (FTC) guidance law based on the second-order sliding mode (SOSM) control theory is proposed to achieve the requirements of stability, accuracy and robustness. More specifically, a second-order sliding mode observer (SMOB) is used to estimate and compensate for the total disturbance of the controlled system, while the target acceleration is extracted from the line-of-sight (LOS) angle measurement. The proposed guidance law can drive the LOS angular rate converge to zero in a finite time, which means that the missile will accurately intercept the target. Numerical simulations with some comparisons are performed to demonstrate the superiority of the proposed guidance law.

• Journal of the Korea Institute of Military Science and Technology
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• v.5 no.3
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• pp.62-76
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• 2002

This paper describes the design of a Coordinates Tracking algorithm for EOTS and its error analysis. EOTS stabilizes the image sensors such as FLIR, CCD TV camera, LRF/LD, and so on, tracks targets automatically, and provides navigation capability for vehicles. The Coordinates Tracking algorithm calculates the azimuth and the elevation angle of EOTS using the inertial navigation system and the attitude sensors of the vehicle, so that LOS designates the target coordinates which is generated by a Radar or an operator. In the error analysis in this paper, the unexpected behaviors of EOTS that is due to the time delay and deadbeat of the digital signals of the vehicle equipments are anticipated and the countermeasures are suggested. This algorithm is verified and the error analysis is confirmed through simulations. The application of this algorithm to EOTS will improve the operational capability by reducing the time which is required to find the target and support especially the flight in a night time flight and the poor weather condition.

• Journal of the Optical Society of Korea
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• v.9 no.2
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• pp.79-83
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• 2005

Spatial calibrations have been performed on the Medium-sized Aperture Camera (MAC) of the RazakSAT satellite. Topics discussed in this paper include the measurements of system modulation transfer function (MTF), relative pixel line-of-sight (LOS), and end-to-end imaging tests. The MTF measurements were made by capturing the scanned knife-edge image on a pixel, and an issue in the MTF calculation algorithm is discussed. The method used to place the focal plane at the correct focal position is described, since they make use of MTF measurements. Relative LOS measurements are done by theodolite measurements of the telescope. Qualitative ground test result of end-to-end imaging is given.

• Proceedings of the KIEE Conference
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• 2003.07d
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• pp.2088-2090
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• 2003

A practical recursive weighted least square(WLS) solution is proposed to solve the passive ranging problem. Apart from the previous works based on the extended Kalman filter(EKF), to ensure the convergency at long-range, the proposed scheme makes use of line-of-sight(LOS) rate instead of bearing information. The influence of LOS rate measurement errors is investigated and it is asserted that the WLS estimates contain bias and scale factor errors. Together with simple compensation algorithm, the estimation errors of proposed filter can be reduced dramatically.