• Journal of Positioning, Navigation, and Timing
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• 제11권3호
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• pp.181-189
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• 2022

The public open signals from Global Navigation Satellite System (GNSS) including Global positioning system (GPS) are used widely by many peoples in the world except for the public regulated restriction signals which are encrypted. Nowadays there are growing concerns about GNSS signal spoofing which can deceive the GNSS receivers by abusing these open services. To counter these spoofing threats, many researches have been studied including array antenna techniques which can detect the direction of arrival by means of Multiple Signal Classification (MUSIC) algorithm. Originally the array antenna techniques were developed to countermeasure the jamming signal in electronic warfare by using the nulling or beamforming algorithm toward a certain direction. In this paper, we study the anti-spoofing techniques using array antenna to overcome the jamming and spoofing issues simultaneously. First, we will present the theoretical analysis results of spoofing signal response of Minimum Variance Distortionless Response (MVDR) algorithm in array antenna. Then the eigenvector algorithm of covariance matrix is suggested and verified to work with the existing anti-jamming method. The modeling and simulation are used to verify the effectiveness of the anti-spoofing algorithm. Also, the field test results show that the array antenna system with the proposed algorithms can perform the anti-spoofing function. This anti-spoofing method using array antenna is very effective in the view point of solving both the jamming and spoofing problems using the same array antenna hardware.

• 시스템엔지니어링학술지
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• 제8권1호
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• pp.63-75
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• 2012

For the definition of development project, this paper proposes an integrated design model for the project 3P's(Products, Process, and People) architecture solutions balancing the originating requirements as well as the design targets of product, process, and IPDT. The model is suggested to develop the integrated design method with trade-off analysis and alternatives evaluation of products, processes, and IPDT using QFD.

• 전자공학회논문지SC
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• 제39권2호
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• pp.116-122
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• 2002

위상정합(coherent) 레이더에 대한 EA 효과를 다양하게 분석할 수 있는 타이밍 (timing) 신호 발생기를 설계 및 제작하였다. 제작한 신호발생기는 EA 장비 및 위상정합 레이더에 필요한 각종 타이밍 신호 및 모의 표적신호를 실시간으로 발생하며, 모의 표적신호 발생기능은 레이더에 대한 EA 효과를 쉽게 확인할 수 있도록 하여준다. 타이밍신호의 모든 파라미터는 프로그램에 의해 변경 가능하기 때문에, 다양한 형태의 시험 시나리오를 쉽게 구성할 수 있다.

• 한국군사과학기술학회지
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• 제21권5호
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• pp.684-696
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• 2018

The mission in missile systems can be conducted with multiple phases according to the characteristics of the systems and the targets. The safeguarded multi-phase mission includes a safeguarded phase before launch for considering the safety of operators in unexpected squib activation. However, the safeguard function should be disabled after launch to complete the mission. Therefore, the squib system needs to be selectively activated according to the phases. This paper presents a selective squib activation and check circuit design for safeguarded multi-phase missions in missile systems. The presented circuit design was implemented with various electronic components including a field-programmable gate array(FPGA). Its functions and performance were validated by both many ground tests and several flight tests.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2007년도 추계학술대회 논문집
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• pp.53-55
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• 2007

This paper describes an implementation of a wide-range dimming controller of a LED backlight for Avionics applications such as the control data unit(CDU) and multi-function display(MFD). A feedback controller using a light sensor is proposed to control the brightness in the low dimming range. The proposed controller provides an improved control performance in the wide dimming range of 1:3000 even under the temperature variations. The experimental results are provided to show the effectiveness of the proposed control system.

• 시스템엔지니어링학술지
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• 제5권1호
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• pp.49-56
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• 2009

This research attempts to acquire technical performance measure information based on identifying the Critical To Quality(CTQ) parameters of user requirement by using Quality Function Deployment(QFD) methodology in the initial phase of a defense R&D project. This results will contribute to the integration of technical progress to the Work Breakdown Structure(WBS) based project performance tracking. It also improve the bridging of systems engineering activities to the project management and the project decision making process.

• 대한산업공학회지
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• 제36권2호
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• pp.108-116
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• 2010

The maintenance of a deteriorating system is often imperfect. Previous studies have shown that the imperfect preventive maintenance (PM) can reduce the wear out and aging effects of deteriorating systems to a certain level between the conditions of as good as new and as bad as old. In this paper, we employ the concept of the improvement factor in investigating two optimal PM policies; failure limit policy and periodic PM policy. We redefine the improvement factor model as a function of the cost of PM, using this concept, we derive the conditions of optimal PM policies and formulate expressions to compute the expected cost rate. Based on this information, the determination of the maintenance policies which minimize the cost rate is examined. Numerical examples for the Weibull distribution case are also given.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2008년도 하계종합학술대회
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• pp.973-974
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• 2008

As radar signal environments become denser and more complex, the capability of high-speed and accurate signal analysis is required for ES(Electronic warfare Support) system to identify individual radar signals at real-time. In this paper, we propose the new novel clustering algorithm of radar pulses to alleviate the load of signal analysis process and support reliable analysis. The proposed algorithm uses KDE(Kernel Density Estimation) and its CDF(Cumulative Distribution Function) to compose clusters considering the distribution characteristics of pulses. Simulation results show the good performance of the proposed clustering algorithm in clustering and classifying the emitters.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.38-42
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• 2002

An apparatus was developed to repetitively apply a $-196^{\circ}C$ thermal load to coupon-sized mechanical test specimens. Using this device, IM7/5250-4 (carbon / bismaleimide) cross-ply and quasi-isotropic laminates were submerged in liquid nitrogen ($LN_2$) 400 times. Ply-by-ply micro-crack density, laminate modulus, and laminate strength were measured as a function of thermal cycles. Quasi-isotropic samples of IM7/977-3 (carbon / epoxy) composite were also manually cycled between liquid nitrogen and an oven set at $120^{\circ}C$ for 130 cycles to determine whether including elevated temperature in the thermal cycle significantly altered the degree or location of micro-cracking. In response to thermal cycling, both materials micro-cracked extensively in the surface plies fellowed by sparse cracking of the inner plies. The tensile modulus of the IM7/5250-4 specimens was unaffected by thermal cycling, but the tensile strength of two of the lay-ups decreased by as much as 8.5%.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2001년도 추계학술대회 논문집 Vol.14 No.1
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• pp.398-401
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• 2001

Indium tin oxide films were deposited on unheated PET substrates by DC reactive magnetron sputtering of In-Sn (90-10 wt%) metallic alloy target. Electrical and optical properties of as-deposited films were systematically studied by control of the deposition parameters such as working pressure, DC power, and oxygen partial pressure. The figures of merit are important factors that summarize briefly the relationship between electrical and optical properties of transparent conducting films. The formulae of $T/R_{sh}$ and $T^{10}/R_{sh}$ are expressed as a function of transmittance and sheet resistance. The best values of those figures of merit were approximately 38.6 and $8.95({\times}10^{-3}\Omega^{-1})$ respectively.