• Journal of the Korean Society for Precision Engineering
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• v.11 no.5
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• pp.124-133
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• 1994

Many of non-contact measuring systems are used to estimate surface characteristics owing to their advantages of high speed and undanaged test. In this paper, a new measuring system is proposed to acquire image from CCD camera through back light illumination. Lowpass filter is very useful in view of noise removal and optimum binary image can be made through histogram equalization which is one of the histogram technique to maximize brightness intensity between workpiece and background. Laplacian operator is used to detect workpiece edge from binary image. In case of image treatment applying Laplacian operator, surface roughness is calculated by introducing conversion coefficient for coordinate of pixel which edge is composed of. In summary, the work is concerned with the development of a new technique for roughness measurement by the image processing in turning.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.36S no.6
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• pp.96-103
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• 1999

This paper proposes efficient VLSI architecture for computation of the 1-D discrete wavelet transform (DWT). The proposed VLSI architecture computes the wavelet lowpass and highpass output sequences using the product term anhm, $n,m{\ge}0$, where an and hm denote the imput sequence and the wavelet lowpass filter coefficient, respectively. Whereas the conventional architectures compute the lowpass and highpass output sequences using the product terms anhm and angm, respectively, where gm denotes the wavelet highpass filter coefficient. The proposed architecture is applied to computation of the Daubechies 4-tap wavelet transform using the relationships between the Daubechies wavelet filter coefficients. Performance comparison of various architectures for computation of the 1-D DWT are presented. Note that the proposed architecture does not require extra processing units whereas the conventional architectures need them. Also it is modeled in very high speed integrated circuit hardware description language (VHDL) and simulated to show its functional validity.

• Journal of the Korean Institute of Intelligent Systems
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• v.24 no.1
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• pp.22-27
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• 2014

Blocking and ringing artifacts continue to be the most serious defects that occur in images and video streams compressed to low bit rates using block-based discrete cosine transform(DCT) compression standards. These artifacts contain the high frequency components near the block and the edge boundaries. Usually the lowpass filter can remove them. However, simple lowpass filter results into blur by removing important information such as edges at the same time. To overcome these problems, we propose a novel postfiltering algorithm that calculate the weight value based on the intensity similarity in the neighboring pixels and multiply this weight to the Gaussian lowpass filter coefficient. Experimental results show that the proposed technique provides satisfactory performance in both objective and subjective image quality.

• Aerospace Engineering and Technology
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• v.1 no.2
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• pp.105-112
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• 2002

In this paper, a servo filter design for the gimbal engine actuator system of KSR-III(Korea Sounding Rocket-III) is considered. A reasonable filter structure is determined based on the actuator analytic models. The servo filter consists of a 2-nd order lowpass filter and a 1-st order compensator. The lowpass filter is required to protect the actuator from high frequency vibration, and the compensator to enhance the resulting stability. A Butterworth type servo filter is considered as the simplest one. The final servo filter type is determined by evaluating simultaneously both high frequency gain reduction performance and the corresponding KSR-III stability margin. Consequently it is revealed that a notch type servo filter located on the error between command signal and feedback signal in the control loop is very effective. Later, based on the proposed servo filter type, an onboard servo filter hardware of KSR-III will be designed and tested.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.14 no.3
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• pp.283-289
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• 2003

In this paper, we proposed novel multilayer photonic bandgap(PBG) structure using DSL(Descended Signal Line). From measurement result, the proposed PBG structure using DSL is reduced 72 % at size and increased 13 % at bandwidth compared to typical multilayer DGS(Defected Ground Structure). It is also reduced 42 % at size and increased 23 % at bandwidth compared to PBG structure using EGP(Elevated Ground Plane). In case of measurement for manufactured six PBG patterns, all patterns have the same cutoff frequency and bandstop characteristics. So it can be used for bandstop filter having very precise tolerance of below 300 MHz at 20 ㎓ if it is applied to real product and this filter will be useful for small microwave integrated circuit and module development.

• Journal of Korea Multimedia Society
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• v.5 no.6
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• pp.753-758
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• 2002

In this paper, low voltage 3V CMOS programmable gain amplifier(PGA) for using in the transmitter and receiver of ADSL analog front-end is designed. The designed receive PGA is connected with 1.1MHz continuous lowpass fillet and controls the gain from 0dB to 30dB. And also the transmitter PGA is connected with 138KHz lowpass filter and controls the gain from -15dB to 0dB. The gain of All PGAs can be programmed by digital logic circuits and main controller. The designed PGAs are verified using HSPICE simulation with $0.35\mu{m}$ CMOS parameter.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.12C
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• pp.1214-1221
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• 2005

In this paper, we propose a digital watermarking method for still images, in which the human visual system (HVS) is used in the discrete cosine transform (DCT) domain. The modulation transfer function (MTF) of the HVS model is employed to increase the invisibility of the inserted watermark in images. The proposed watermarking method is shown to be robust to several common image processing techniques, including lowpass filtering and cropping. Also, using the energy relationship of the DCT, we derive the equation that directly computes the watermark weighting factor in the DCT domain for the specified peak signal to noise ratio (PSNR) of the still image and the length of watermark to be inserted. The difference between desired PSNR and PSNR in spatial domain is within 0.07dB for the 7 test images.

• Proceedings of the KIEE Conference
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• 2000.07d
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• pp.3233-3235
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• 2000

A new method for HRV(heart rate variability} detection from the R-wave signal, based on the IPFM (integral pulse frequency modulation) model and its similarity to pulse position modulation, is presented. The proposed method exert lowpass filtering with a Kaiser window. In this paper, The proposed method presents a powerful, but simple, tool for investigation of HRV. It also guarantees real-time behavior, simplicity in design, and phase linearity. Even without the basic assumption of IPFM model, the new algorithm can still be used on-line and with higher performance. It is thoroughly proved that lowpass filtering is an ideal method for PSD (Power Spectrum Density) analysis of HRV.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.1405-1409
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• 2010

최근 우리나라는 물 부족 국가로서 물의 효율적 관리 필요성 증대, 기후변화에 따른 가뭄 홍수 피해 증가 등으로 신뢰성 있는 수문자료구축이 필요성이 요구되고 있다. 그 중 유량측정 분야는 모든 수자원 계획과 관리의 근간이 되는 분야로 그 중요성 또한 간과 할 수 없는 부분이다. 현재 우리나라에서는 한국건설기술연구원 산하 유량조사사업단에 의해 유량측정 주요지점에 자동유량측정 시설을 설치하고 이를 운영함으로써 각 지점의 특성에 따라 적절한 방식을 채택하여 이동시간차방식 초음파 유속계(UVM, Ultrasonic Velocity Meter)와 도플러방식 초음파유속계(ADVM, Acoustic Doppler Velocity Meter)를 설치하면서 향후 수문계측 분야 선진화를 위한 기초자료를 제공하고 있다. 하지만 실시간 무인화 계측시스템에 의해 제공되는 자료가 양질의 자료임을 보장할 수 없는 현실이기 때문에 측정된 기초자료의 필터링을 통한 자료의 질적 개선이 필요하다. 따라서 본 연구에서는 기존에 전산분야의 필터링 방법으로 널리 알려져 있는 LPF(Lowpass Filter)와 KF(Kalman Filter)를 이용하여 자동유량측정 자료의 필터링 방법으로 활용하고, 그 적용성을 검토하였다. 본 연구를 통해 기존 유량자료의 문제점을 개선하고 효율적인 유량조사를 위한 기초자료 확보 방법으로 활용될 수 있을 것으로 기대된다.

• The Journal of the Korea institute of electronic communication sciences
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• v.13 no.5
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• pp.965-970
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• 2018

In this paper, the transition of the folded substrate integrated waveguide (FSIW) using two substrates is suggested and applied to the bandpass filter. The FSIW has similar characteristics with the SIW and can be reduced the width of the SIW. The transition between the FSIW to the microstrip is designed by using shorted quarter wavelength line. Also, the bandpass filter is designed by using the FSIW and the elliptic lowpass filter of 5 section. Fabricated bandpass filter has the center frequency of 5.75 GHz and the bandwidth of 33.2%. Also, the insertion loss and return loss at the center frequency are 0.63dB and 19.1dB, respectively.