• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.5 s.176
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• pp.1133-1145
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• 2000

It is necessary to develop an efficient analysis method to identify the dynamic characteristics of a large mechanical structure and update its finite element model. That is because these processes need the huge computation of a large structure and iterative estimation due to the use of the first- order sensitivity. To efficiently carry out these processes, a new method, called the generalized free-interface mode sensitivity method, has been proposed in the authors' preceeding paper. This method is based on substructuring approach such as a free-interface method and a generalized synthesis algorithm. In this paper, the proposed method is applied to the model updating of a car body structure to verify its accuracy and reliability for a large mechanical structure.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.185-187
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• 2017

국제 표준화 기구인 ISO/IEC와 NIST(National Institute of Standards and Technology)에서는 정보 유출 방지 및 정보의 유효성 인증을 위해 다양한 암호 기법들을 표준으로 권고하고 있다. 그 중 NIST SP 800-38D에서 표준으로 권고된 GCM(Galois/Counter Mode) 인증 암호화 모드는 블록암호의 CTR 운영모드와 GHASH를 이용하여 메시지의 기밀성과 무결성을 동시에 제공하는 운영모드이다. 본 논문에서는 ARIA 블록암호 기반의 ARIA-GCM 프로세서를 Verilog HDL로 모델링 하고, Virtex5 FPGA로 구현하여 정상 동작함을 확인하였다. $0.18{\mu}m$ 공정의 CMOS 셀 라이브러리로 합성한 결과 20 MHz의 동작주파수에서 44,986 GE로 구현되었다.

• Journal of Biomedical Engineering Research
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• v.20 no.4
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• pp.503-513
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• 1999

A general expression for the beam patterns of various synthetic aperture(SA) techniques was derived based on a unified SA model. This model was used to analyze and compare the performance of existing SA methods. Based on the theoretical studies, we propose a new synthetic aperture technique that is best suitable for the linear-scan imaging. The proposed method enables dynamic tow-way focusing in real imaging so that the B-mode image resolution can be greatly improved. Compared to the conventional focusing technique, the focused beam pattern by the proposed shows the mainlobe width reduced by half and comparable sidelobe levels. Computer simulation results demonstrated the validity of the theoretical analysis and the proposed SA method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.10a
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• pp.669-670
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• 2009

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.11a
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• pp.664-665
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• 2008

• Aerospace Engineering and Technology
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• v.3 no.2
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• pp.34-41
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• 2004

In this paper, the SAR operational mode for achieving mission is designed. Each mode, which is the strip mode, scan mode, and fine mode, is basically considered. Based on the characteristics, which includes incidence angle, of the topography in Korean Peninsula, look angle for SAR satellite is determined. The limited region of operating the mission, which is considered to be able to receive and transmit the radar data, was defined to use determined operational mode. In the future, as considering full requirements and conditions for the SAR satellite, requirements and parameters will be discussed and studied.

• Proceedings of the Korea Information Processing Society Conference
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• 2013.11a
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• pp.1532-1535
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• 2013

변환 블록은 영상 압축에서 데이터를 공간적 영역에서 주파수 영역으로 변환해줌으로써 압축의 효율성을 높이는 역할을 수행한다. 본 논문에서는 고성능 HEVC를 위한 4개의 TU 모드($4{\times}4$, $8{\times}8$, $16{\times}16$, $32{\times}32$)를 지원하는 변환 블록 하드웨어 구조를 제안한다. 제안하는 변환 블록의 하드웨어 구조는 공통 연산기를 사용하여 각 TU 모드에 맞는 행렬 계수들 간의 연산을 수행한다. 또한 병렬적인 구조로 설계하여 $4{\times}4$, $8{\times}8$, $16{\times}16$, $32{\times}32$ 크기 TU 모드의 행렬 연산을 처리하는 사이클수가 35cycle로 동일하게 처리된다. TSMC 180nm CMOS 공정 라이브러리를 통해 합성한 결과 $4k(3840{\times}2160)@30Hz$의 영상을 기준으로 최대 동작주파수는 400MHz이고 총 게이트 수는 159k이며, 10-Gpels/cycle의 처리량을 갖는다.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.6
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• pp.599-605
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• 2003

A dual-mode asymmetric canonical filter is widely used in an input demultiplexer for satellite transponder. This paper deals with a simple synthesis method fur an asymmetric canonical filter. The coupling matrix of an asymmetric canonical filter is obtained by applying plane rotation technique to the coupling matrix of a symmetric canonical filter. This paper gives a list of pivots and rotation angles to obtain the coupling matrix of asymmetric canonical structure filters. The coupling matrix of 8th and 10th order asymmetric canonical filter is obtained by this proposed method. It is shown that the frequency response of asymmetric canonical filter is identical to that of symmetric canonical filter.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.4
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• pp.302-309
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• 2002

A FRF-based substructuring method attempts to predict the dynamic characteristics of a complex structure from predetermined FRFs of the comprising uncoupled substructures. Although this method has the advantage of being able to incorporate experimental component FRFs directly, it is prone to errors : measurement errors, coordinate incompleteness, modal incompleteness, etc. Among the various sources of errors, this paper deals with the problem of modal incompleteness (or residual problem) of which importance is underestimated compared to others. It is a well-known rule of thumb that such a problem can be overcome by including modes up to 2 or 3 times the upper frequency of interest. Using a simulated case study, it is demonstrated that even including modes up to 20 times the upper frequency of interest does not guarantee a satisfactory result. A method to compensate the residual errors is introduced. This method requires the whole FRF matrices of substructures which is practically impossible for a complex structure. An applicable alternative is suggested and applied successfully to the case study. Finally, the effects of measurement errors on the residual compensation are also discussed.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.1
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• pp.57-63
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• 2014

In this paper, we have proposed a wide band antenna for manpack SDR(Software Defined Radio). The proposed antenna consists of feeding post, flexible gooseneck and two radiating elements composed of a upper and lower radiators. The upper radiator has a longer electrical length than the lower radiator in order to operate in the lower frequency. Also, the resonant frequency and impedance characteristics of the antenna can be adjusted independently for two radiators. Therefore, the proposed antenna can be achieved wide impedance bandwidth by the combination of two independent resonance modes. To analyze the characteristics of the antenna in the design process is employed the equivalent circuit theory and EM(Electro-Magnetic) simulation. The measurement results show that the proposed antenna have the sufficient wide bandwidth, above -3.4dBi of the gain and fairly good radiation pattern over the wide bandwidth.