• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.7
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• pp.705-710
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• 2011

In this paper, we proposed the low computational complexity soft-decision e-BCH decoding algorithm based on the Chase algorithm. In order to make the test patterns, it is necessary to re-order the least reliable received symbols. In the process of ordering and finding optimal decoding symbols, high computational complexity is required. Therefore, this paper proposes the method of low computational complexity algorithm for soft-decision e-BCH decoding process.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.3
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• pp.299-309
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• 2013

A comprehensive SAR(Synthetic Aperture Radar) simulation is considered to be a complicated task since a full knowledge of the signal propagation characteristics, antenna pattern, system internal errors and interference noises should be taken into account. In high resolution target application modes, the time varying nature of target RCS(Radar Cross Section) strongly affects the generated SAR images. In this paper, in-depth SAR simulations are performed and analyzed incorporating the STK tools and MATLAB software. STK provides realistic orbit parameters while its radar module helps to extract accurate radiometric parameters of ground targets. SAR raw data corresponding to a given target is generated and processed using MATLAB simulator. The performance is measured by PSLR(Peak Sidelobe Ratio) and ISLR(Integrated Sidelobe Ratio) for a point target, which can be used as reference parameters for accurate radiometric calibration. Finally, high resolution target simulations are performed by adopting time varying target RCS characteristics.

• Journal of Information Processing Systems
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• v.5 no.1
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• pp.33-40
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• 2009

Ever since the network-based malicious code commonly known as a 'worm' surfaced in the early part of the 1980's, its prevalence has grown more and more. The RCS (Random Constant Spreading) worm has become a dominant, malicious virus in recent computer networking circles. The worm retards the availability of an overall network by exhausting resources such as CPU capacity, network peripherals and transfer bandwidth, causing damage to an uninfected system as well as an infected system. The generation and spreading cycle of these worms progress rapidly. The existing studies to counter malicious code have studied the Microscopic Model for detecting worm generation based on some specific pattern or sign of attack, thus preventing its spread by countering the worm directly on detection. However, due to zero-day threat actualization, rapid spreading of the RCS worm and reduction of survival time, securing a security model to ensure the survivability of the network became an urgent problem that the existing solution-oriented security measures did not address. This paper analyzes the recently studied efficient dynamic network. Essentially, this paper suggests a model that dynamically controls the RCS worm using the characteristics of Power-Law and depth distribution of the delivery node, which is commonly seen in preferential growth networks. Moreover, we suggest a model that dynamically controls the spread of the worm using information about the depth distribution of delivery. We also verified via simulation that the load for each node was minimized at an optimal depth to effectively restrain the spread of the worm.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.25 no.8
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• pp.1110-1116
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• 2021

In this paper, we propose a conformal Ku-band data link antenna to ensure low RCS of stealth UAV. As a phased array antenna with electrical beam steering function, a transmitter and a receiver were designed and manufactured for FDD communication, respectively. Each antenna is designed as a 12*12 planar array antenna and has a function to form a uni-directional pattern and a bi-directional pattern through phase control of unit elements. The beam steering range is designed to be able to steer up to 60 degrees in theta direction and 360 degrees in the phi direction. As a result of manufacturing and measurement, the conformal type radome has low transmission loss and meets the required specifications including system performance. The feasibility of mounting the stealth UAV has been confirmed, and future research directions such as interworking of baseband devices and conversion to digital beam steering function are suggested.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.23 no.10
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• pp.1204-1211
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• 2012

Measurement and analysis results of the extracted radiation-patterns from the field-experiments which were conducted to acquire the generic technology for calibration and validation of the satellite SAR system(Synthetic Aperture Radar) are presented in this study. Prototype of active transponder is adjustable within maximum 63.1 dBsm of RCS (Radar Cross Section) and includes the receiving-function with external receiver. To increase an accuracy of these field experiments, we repetitively measured satellite SAR systems of the same operating mode(i.e., COSMO-SkyMed No. 2 & 3, hh-pol., strip-map himage mode, 3 m resolution). Then, the reliability of experimental results was cross-checked through analysis of the RCS of active transponder on SAR image. The property of azimuth radiation patterns of satellite SAR system extracted from them has $0.352^{\circ}$ of HPBW(half-power beamwidth), $0.691^{\circ}$ of FNBW(first-null beamwidth), and 11.17 dB of PSLR(peak to side lobe ratio), respectively.

• Journal of Auto-vehicle Safety Association
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• v.4 no.2
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• pp.32-36
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• 2012

The Automatic unmanned target object carrying system (AUTOCS) is developed for testing road vehicle radar and vision sensor. It is important for the target to reflect the realistic target characteristics when developing ASV or ADAS products. The AUTOCS is developed to move the pedestrian or motorcycle target for desired speed and position. The AUTOCS is designed that only payload target which is a manikin or a motorcycle is detected by the sensor not the AUTOCS itself. In order for the AUTOCS to have low exposure to radar, the AUTOCS is stealthy shaped to have low RCS(Radar Cross Section). For deceiving vision sensor, the AUTOCS has a specially designed pattern on outside skin which resembles the asphalt pattern. The AUTOCS has three driving modes which are remote control, path following and replay. The AUTOCS V.1 is tested to verify the radar detect characteristics, and the AUTOCS successfully demonstrated that it is not detected by a car radar. The result is presented in this paper.

• Journal of the Korea Institute of Military Science and Technology
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• v.24 no.5
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• pp.519-526
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• 2021

In this paper, an array antenna for LOS datalink for mounting UAV(Unmanned Aerial Vehicle) of low-probability of intercept is presented. For low RCS, radome was designed by conformal form, and other components were inserted into the UAV. The antenna of the transmitter and receiver are each composed of 12×12 array antennas, and include a beam steering function by controlling the phase of the unit element for the Uni-directional pattern and the Bi-directional pattern. As a result of the measurement of the manufactured antenna, it was confirmed that all the required specifications were met, and the installing possibility of the UAV platform on low-probability of intercept in the future was confirmed.

• Composites Research
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• v.23 no.2
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• pp.17-23
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• 2010

The stealth technology can increase the survivability of aircrafts or warships and enhance the capability of mission completion in hostile territory. The purpose of this paper is to present the low observable structure with curved surfaces made by fiber-reinforced composites and to show the possibility of developing omnidirectional stealth platforms for military applications. In this study, we developed a radar absorbing structures(RAS) based on a circuit analog absorber to reduce the radar cross section(RCS) of an object with curved surfaces. Firstly, the RAS with a periodic square patterned conducting polymer layer was designed and simulated using a commercial 3-D electromagnetic field analysis program. Secondly, the designed semi-cylindrical structure with low RCS was fabricated using fiber-reinforced composites and conducting polymer. To make the periodic pattern layer, acts as resistive sheet, the intrinsic conducting polymer paste containing PEDOT with a polyurethane binder was used. Finally, the radar cross section was measured to evaluate the radar absorbing performances of the fabricated RAS by the compact range facility in POSTECH.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.26 no.11
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• pp.937-950
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• 2015

Microstrip reflectarray is an antenna which controls its radiation pattern with a number of reflective elements. Conventionally, the reflectarray has been researched to replace curved reflector antennas. In this paper, design theories of reflectarray is briefly introduced, and research trends of high gain and broadband reflectarrays are reviewed. To improve the gain of the reflectarrays, it is required that the reflection phase errors on the reflectarray surface be minimized. For this purpose, sufficiently wide reflection phase range and low phase sensitivity should be realized with the designed element. For bandwidth improvement, the reflection phase of the element should be linear with the frequency variation. In this paper, various researches to improve the reflection phase characteristics of the element for high gain and broadband reflectarrays, such as multi-layer and single-layer multi-resonant structures, are reviewed. Also, dual-reflectarray configuration for compact antenna design is reviewed. Finally, various applications of reflectarrays such as contoured beam, near-field focusing, and RCS reduction are reviewed.

• Proceedings of the KSRS Conference
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• 2008.10a
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• pp.240-242
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• 2008

In the present article, we analyze airborne Pi-SAR (Polarimetric-Interferometric SAR) X-band images of ocean waves around the Miyake Island at approximately 180 km south from Tokyo, Japan. Two images of a same scene were produced at approximately 40 min. interval from two directions at right angles. One image shows dominant range travelling waves, but the other image shows a different wave pattern. This difference can be caused by the different image modulations of RCS and velocity bunching. We have estimated the dominant wavelength from the image of range waves, and from the wave phase velocity computed from the dispersion relation (though no wave height data were available), the image intensity is computed by using the velocity bunching model. The comparison of the result with the second image at right angle strongly suggests the evidence of velocity bunching.