• The Journal of Korean Institute of Communications and Information Sciences
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• v.25 no.9A
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• pp.1306-1312
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• 2000

The quality loss of a X-band transmitter has been derived by means of MC simulation. The transmitter as a payload of LEO(Low Earth Orbit) satellite is capable of the down transmission the image data of hundreds Mbps generated from the Electro-Optical Instrument in real time. The parameters such as data asymmetry amplitude unbalance,phase unbalance, wave shaping and channel interference are included in the quality loss simulation Assuming that normally distributed gaussian noise is simply added to the channel, the quality loss of 0.7 dB has been obtained through this simulation based on a 95% confidence interval. The obtained quality loss can be applied to the link budgets as an additional loss item.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.11 no.7
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• pp.1258-1270
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• 2000

A synthetic aperture radar (SAR) system is able to provide all-weather, day-and-night, high resolution imaging capability in the wide area of interest, and thus is extremely useful in surveillance for both civil and military applications. In this paper, the X-band high-resolution spaceborne SAR system design is described with the key design parameters for the mission and system requirement characterized by the small satellite platform. The SAR imaging mode design technique is presented, and the standard imaging mode design results are analyzed with respect to image quality performance. In line with the system requirement, X-band SAR payload and ground reception/processing subsystems are designed and the key design results are demonstrated with the outstanding performance characteristics. The designed small satellite SAR system shows the wide range of imaging capability, and proves to be an effective surveillance systems in the light weight, high performance and cost-effective points of view.

• Journal of Aerospace System Engineering
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• v.18 no.2
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• pp.104-116
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• 2024

A satellite is ultimately verified by performing a coupled load analysis with the launch vehicle. To increase the accuracy of the coupled load analysis results, it is important to have good accuracy of the finite element model. Therefore, finite element model correlation is essential. In general, model correlation is performed by changing the material properties and thickness one by one, but this process takes a lot of time and cost. The current paper proposes an efficient model correlation method using optimization. Significant variables were selected through analysis of variance, and the time and cost required for analysis and optimization were reduced by using the Kriging surrogate model. The method proposed in this paper can be applied only with the vibration test results, and it has a great advantage in terms of efficiency in that it can significantly reduce the numerical calculation cost and time required.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.29 no.8
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• pp.624-631
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• 2018

To meet the requirements of various satellite synthetic aperture radar(SAR) system performance parameters, the characteristics of the antenna pattern should be analyzed. In this paper, we propose a method to improve the SAR system performance using an effective technique for optimizing antenna pattern synthesis in the presence of element failure. The desired antenna pattern can be synthesized by referring to the optimized antenna mask templates using the particle swarm optimization algorithm. In the simulation, the performance of the proposed method is verified by analyzing characteristics related to the SAR system performance parameters using antenna pattern regeneration.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.30 no.7
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• pp.113-122
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• 2002

Control system modeling and optimal bending filter design for KSR-III (Korea Sounding Rocket III) are performed. Rigid rocket dynamics, aerodynamics, sloshing, structural bending, actuator dynamics, sensor dynamics and on-board computer characteristics are considered for control system modeling. Compensation for time-varying control system parameters is conducted by gain-scheduling. A filter to stabilize bending mode is designed using parameter optimization technique. Resultant attitude control system can satisfy required frequency domain stability margin.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.358-363
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• 2017

The high intercept probability depends on optimization of the system, which consists of target detection, tracking system, missile system and so on. To reduce the complexity of global optimization of the system performance, simplification of the relative dependances of each sub-system is done and design parameters for DACS configuration are identified. The conceptual design process is addressed based on the requirement of the design parameters and new methodology is suggested for higher performance.

• Proceedings of the Korean Information Science Society Conference
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• 2011.06b
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• pp.79-82
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• 2011

무인기용 비행제어 소프트웨어는 인터럽트 핸들러에서 비결정적인 수행결과를 조래하는 경합이 발생될 수 있다. 이러한 유형의 경합을 탐지하기 위한 기존 방법은 원시 프로그램의 인터럽트 핸들러를 스레드로 변환하여 정적 경합탐지 도구를 사용하므로 프로그램 수행 시 실제 발생하지 않는 부정확한 경합(false positives)를 보고한다. 본 연구는 부정확한 경합 보고를 줄이기 위해서 원시 프로그램을 POSIX 실시간 스레브 프로그램으로 변환하고 Lockset기반 탐지기법 의해서 탐지된 공유변수를 대상으로 Happens-before 관계 분석기법을 이용하여 경합을 탐지하는 동적 경합탐지 도구를 사용한다. 제시된 방법의 실험을 위해서 Knob Assembly에 탑재되는 비행제어 소프트웨어를 대상으로 정적 경합탐지 도구와 동적 경합탐지 도구의 경합탐지 결과를 비교 분석한다.

• Proceedings of the KSRS Conference
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• 2006.03a
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• pp.206-209
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• 2006

강우-유출 모델링에 있어 토지피복/이용 상태는 중요한 입력변수로 사용되지만 기존의 다중분광영상을 이용한 분류에는 한계가 있다. 본 연구에서는 위성탑재 초분광영상인 Hyperion 영상의 분광혼합분석을 통해 도시지역의 수문학적 토지피복/이용 분류를 실시하였으며 분류등급의 기준은 널리 사용되고 있는 SCS 토지피복/이용 등급을 이용하였다. 정확도분석을 위해 항공사진을 디지타이징하여 불투수면적의 비율을 비교하였으며 분광혼합분석 결과와 항공사진에서 불투수면적의 비율은 유사하게 나타났다. 그러나 SCS의 분류등급은 미국을 기준으로 개발되었기 때문에 임계치를 이용하여 분류된 등급과 실제 항공사진판독의 결과가 일부 다르게 나타나는 것을 알 수 있었다.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2003.05a
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• pp.115-118
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• 2003

A Propeller as the propulsion system of a target drone has been designed. The vortex theory has been applied for the propeller design method. A compressible effect has been removed and the Reynolds Number assumed to be constant. Design variables have been the chord length and the geometric angle of the blade. The aim of this optimum design has been an efficiency maximization. A performance of the designed propeller has been analyzed.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.2
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• pp.192-198
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• 2013

This paper presents the stabilization and design of a pan-tilt control part for the directional pan-tilt system for shipboard directional equipment. In order to control each control axis with compensation for ship motion, the 2 degree of freedom(2DOF) PID controller is designed and its parameters are tuned using a real-coded genetic algorithm(RCGA). Simulation demonstrates the effectiveness of the 2 DOF PID controller tuning.