• Journal of Biomedical Engineering Research
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• v.11 no.1
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• pp.147-156
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• 1990

A two-dimensional pulsed doppler system for ultrasonic blood velocity doppler signals is studied and implemented. The second-order sampling method and serial data processing procedures are utillized in the sys- tem, which eliminates the untuning problems at phase channels in the quadrature detection method as well as in the channels of parallel data processing. rho digital signal processor used in this system allows a hardware savings and flexible design options. The efficiency of the various mean frequency estimators in the second-order sampling system is examined by computer simulation as a function of the intersequence sample delay time. The temporal delay for the quadrature component is changed from $1/(4f_o){\;}to{\;}3/(4f_o){\;}and{\;}5/(4f_o)$ where to is the center frequency of the transducer, It is found that autocorrelator is the optimum frequency estimator for the second-order sampling: with !he intersequence sample delay of $1/(4f_o){\;}to{\;}3/(4f_o){\;}and{\;}5/(4f_o)$. The qualitative variation and information proportional to blood velocity in the vessel system are obtained in the VIVO experiments.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1824-1827
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• 1998

A Laser Doppler Vibrometer(LDV) was developed using He-Ne laser as a light source. The heterodyne method was employed and its output signal was digitally processed with a $\mu$-processor and the result was displayed with LCD. The frequency shifted object beam(40 MHz) by a Bragg cell was focused on the surface of the moving target and the Doppler shifted reflected beam was recombined with reference beam at the fast photodetector to produce frequency modulated signal centered at 40 MHz. The signal from the detector was amplified and downconverted to intermediate frequency centered at 1 MHz after mixing process. The voltage output that was proportional to the velocity of the moving surface was obtained using PLL. With the same method, the fringe pattern signal of the moving surface is obtained. This fringe pattern signal is converted to TTL signal with ZCD(zero-crossing detector) and then counted to calculate the displacement due to the vibration, which is displayed with LCD. This LDV can be used to measure the resonant frequency of the electric equipments such as circuit breakers and transformers, of which resonant frequencies are changed when they are damaged.

• Proceedings of the KSRS Conference
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• 2007.03a
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• pp.198-203
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• 2007

최근 인공위성 SAR를 이용한 기술은 해풍，파랑，해류 등과 같은 해양에서 발생되는 다양한 현상을 관측하고 연구하는데 펼수적인 기술로 대두되고 있다. CMOD4, CMOD-IFR2 모델은 해상풍의 크기를 구할 수 있으며，wave-SAR 변환 기법과 inter-look cross-spectra 기법은 파랑의 크기，방향과 같은 물리적 값을 추출할 수 있다. 또한 Doppler shift 기법을 적용하여 해류속도를 구할 수 있다. 본 연구에서는 위의 기법들을 종합적으로 적용하여 SOP (SAR Ocean Processor) 프로세서를 개발하였다. 이 프로세서를 한반도 연안 지역에 적용하여 RADARSAT-1 영상자료로부터 해풍，파랑，해류의 물리적 정보를 추출하였으며，이를 현장 관련 자료와 비교하여 신뢰할만한 결과를 얻을 수 있었다.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.34D no.2
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• pp.10-20
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• 1997

This paper describes the design, the manufacture and the development of th eautomatic gain control unit which ajdusts the gain of IF processor in the high sensitive & multifunctional receiver unit (HMR) for pulse doppler radar system. Accodording to the effective distnce of target, radar cross section, and a lot of external environments (such as clutter), the receiving stage of RADAR system often deviates from dynamic range. To solve this kind o fproblem, continuous/pulse wave AGC are realized, make it possible to control the gain characteristics of receiver stably, and can increase dynamic range linearly by adjusting the gain slope of receiver which is limited by 1-dB gain compression point. In this study, AGC unit is designed to regulate the total gain of receiver by using te analog feedback theory. It also has rapid enough response to process pulse signal. This study presents the gain control method of IF, the real manufacture technique (the package-type components) and the measurement performance of AGC.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.31 no.1C
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• pp.46-54
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• 2006

The design method of synthetic aperture radar processor (SARP) in the critical design stage is to describe the processing algorithm, to estimate the fractional errors, and to set out the software (SW) and hardware (HW) mapping. The previous design methods for SARP are complex and depend on HW. Therefore, this paper proposes a critical design method that is of more general and independent of HW. This methodology can be applied for developing the space-based SARP using range-Doppler algorithm (RDA).

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.24 no.7
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• pp.737-747
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• 2013

A 3-D surveillance radar is a pulsed-doppler radar to provide various target information, such as range, doppler and angle by performing TWS. This paper introduces HW/SW architecture of radar signal processing board to process in real-time using high-speed multiple DSP(Digital Signal Processor) based on COTS. Moreover, we introduced a implemented algorithm consisted of clutter map creation/renewal, FIR(Finite Impulse Response) filter for rejection of zero velocity components, doppler filter, hybrid CFAR and finally presented computational burden of each algorithm by performing operational test using a beacon.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.20 no.5
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• pp.71-77
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• 2020

Recently, the tracking radar has confirmed the necessity of developing a small tracking radar that can be operated without various restrictions in various environments. In addition, the performance of a small tracking radar requires equal to or higher than the existing tracking radar. Such a small tracking radar can be implemented through miniaturization and low power of existing tracking radar. In this paper, the role and function of a signal processor for a small tracking radar are defined and we proposed a method to increase the efficiency of power consumption and miniaturization by minimizing the use of devices required to implement a signal processor for a small tracking radar. Used as a method for miniaturization, a device processor such as DDC and communication controller was implemented in an FPGA to design a signal processor for a small tracking radar. In addition, a low-power signal processor was designed by a power supply using a highly efficient switching regulator. Finally, the signal processor was verified by the performance test of the signal processor for the small tracking radar implemented, the Doppler tracking test using the signal processor on the small tracking radar, and the distance tracking test.

• Transactions of the Korean Society of Mechanical Engineers
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• v.11 no.5
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• pp.725-730
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• 1987

An experimental study of the air flow through inlet pipe of reciprocating two-cycle engine was investigated under motored condition. Measurements of the two components of velocity, velocity fluctuation, and the other behavior of inlet flow have been obtained by laser Doppler anemometer system. The research engine comprised the cylinder head of a two-cycle engine which mounted on optical spacer with measuring window and glass inlet entry for laser anemometer measurement. A dual beam laser Doppler anemometer was used with conventional forward scattered method and comprised argon-ion laser, frequency shifter with Bragg cell module, and the signal processor. Measurements of mean velocity fluctuation of inlet flow for different engine speeds, measuring positions, and the changes in cylinder volume are investigated. The results presented show that the changes in engine speed is shown to be strongly influenced on the mean velocity of inlet air. The effect of measuring position and cylinder volume on the inlet velocity was also investigated for the inlet port entry and is shown to be small compared to the engine speed.

• Journal of Advanced Navigation Technology
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• v.21 no.6
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• pp.554-560
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• 2017

Accurate altimetry is required for the reliable flight control of drones or unmanned air vehicles (UAVs), and the radar altimeter is commonly used owing to its accuracy for the ground level. Due to the limitation for size, weight and power consumption, the frequency modulated continuous wave (FMCW) radar is appropriate for drone because it has lower complexity than that of pulse Doppler (PD) radar. Especially, fast-ramp FMCW radar, which transmits linear FM signal during very short period, is generally utilized, because it is robust for the ego-motion of drone. Therefore, we present the design and implementation results of the radar signal processor (RSP) for fast-ramp FMCW radar system. The proposed RSP was designed with Verilog-HDL and implemented with Altera Cyclone-IV FPGA device. Implementation results show that the proposed RSP includes 27,523 logic elements, 15,798 registers and memory of 138Kbits and can measure the altimeter at the rate of 100Hz with the operating frequency of 50MHz.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.22 no.12
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• pp.1045-1059
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• 2011

A 3-D multi-function radar(MFR) is a modern radar to provide various target information, such as range, doppler, and angle by performing surveillance, multiple target tracking, and missile guidance. In this paper, we introduced a real-time radar signal processor(RSP), which is a crucial component of MFR with its design, implementation using high-speed multiple DSP, and performance. Additionally, we verified that several advanced signal processing algorithms were well-performed in our RSP, such as MCA-CFAR algorithm for target detection in clutter environment, range and velocity measurement algorithm using discriminator estimation, and noise jammer detection algorithm using local minimum selection.