An Efficient Technique for the design of Maximally flat Zero-phase Digital Filters with wideband response

Joonhyeon Jeon 대한전자공학회 2007 ITC-CSCC :International Technical Conference on Ci Vol.2007 No.7

In this paper, we propose an efficient technique for the design of zero-phase wideband maximally flat lowpass FIR filters with the stopband attenuation exceeding 300 ㏈ almost everywhere. The technique is based on a wideband closed-form transfer function with real and even impulse response and is realized due to generalized-coefficient formulas derived by maximally flat constraints including an arbitrary cutoff point.

MAXFLAT FIR 필터의 일반적이고 간편한 설계를 위한 새로운 기술

전준현(Joonhyeon Jeon) 한국통신학회 2010 韓國通信學會論文誌 Vol.35 No.4

주파수영역 오차함수의 모델링과 분석을 통한 제로위상 FIR 필터 설계

전준현(Joonhyeon Jeon) 한국통신학회 2011 韓國通信學會論文誌 Vol.36 No.7

에지 패턴 기반 계층적 이동 보상 피라미드 부호화 방식 연구

전준현(JoonHyeon jeon) 한국통신학회 2003 한국통신학회 학술대회논문집 Vol.2003 No.7

근접 완전재생 Pseudo-QMF 뱅크를 위한 선형위상 프로토타입 저역통과 필터의 효율적인 설계 방법

전준현(Joonhyeon Jeon) 한국통신학회 2008 韓國通信學會論文誌 Vol.33 No.3C

M채널 NPR(Near-Perfect Reconstruction) pseudo-QMF(Quadrature Mirror Filter) 뱅크의 설계는 일반적으로 SF(Spectral Factorization) 접근 방식을 혼합하여 많이 사용하며, 분리와 합성 필터들은 프로토타입 저역통과 필터 (prototype lowpass filter : p-LPF)를 코사인 변조하여 사용한다. 그러나 이 방식은 2M<SUP>-th</SUP> 대역 필터 G(z)=z<SUP>-(N-1)</SUP>H(z<SUP>-1</SUP>)H(z)의 SF 방식에 의해 p-LPF H(z)을 설계하기 때문에 p-LPF가 선형위상을 갖지 못할 뿐만 아니라 진폭왜곡이 최적화되지도 않았다. 따라서 대부분의 방법들이 재생 진폭왜곡 보다는 중첩상쇄왜곡을 줄이기 위한 p-LPF 설계를 제안하였다. 본 논문에서는 NPR pseudo-QMF 뱅크 구현에 필요한 p-LPF 설계를 위해 폐쇄형전달함수를 갖는 선형위상의 Maxflat(maximally flat) FIR 필터를 이용하는 새로운 방식을 제안하였다. 또한 폐쇄형주파수함수를 이용하여 2M<SUP>-th</SUP> 대역 필터 G(z)=H²(z)로 표현되는 2M개 채널들의 전체진폭응답이 단일응답을 갖도록 p-LPF H(z)을 최적화하는 방법이 제안되었다. 실험 결과 시스템 최대진폭 왜곡이 3.5×10<SUP>-4</SUP> (?-70㏈)보다 적고 각 분리 및 합성 필터들의 저지대역 감쇠가 -100㏈ 이상의 매우 뛰어난 NPR pseudo-QMF 뱅크 설계가 가능함이 증명되었다. M channel near-perfect-reconstruction(NPR) pseudo-QMF banks are a hybrid of conventional pseudo-QMF design and spectral factorization approach where the analysis and synthesis filters are cosine-modulated versions of the prototype-lowpass filter(p-LPF). However, p-LPF H(z) does not have linear-phase symmetry as well as magnitude-distortion optimization since it is obtained by spectral factorization of 2M<SUP>-th</SUP> band filter G(z)=z<SUP>-(N-1)</SUP>H(z<SUP>-1</SUP>)H(z). A fair amount of attention , therefore, has been focused on the design of filter banks for reducing only alias-cancellation distortion without reconstructed-amplitude distortion. In this paper, we propose a new method for designing linear-phase p-LPF in NPR pseudo-QMF banks, which is based on Maxflat(maximally flat) FIR filters with closed-form transfer function. In addition, p-LPF H(z) is optimized in this approach so that the 2M-channel overall distortion response represented with G(z)=H²(z) approximately becomes an unit magnitude response. Through several examples of NPR pseudo-QMF banks, it is shown that the peek ripple of the overall magnitude distortion is less than 3.5×10<SUP>-4</SUP> (?-70㏈) and analysis/synthesis filters have the sharp monotone-stopband attenuation exceeding 100 ㏈.

Study on Durability and Stability of an Aqueous Electrolyte Solution for Zinc Bromide Hybrid Flow Batteries

Kim, Donghyeon,Jeon, Joonhyeon IOP Publishing 2015 Journal of Physics: Conference Series Vol.574 No.1

Contrast Enhancement of Medical Images by Combining Fuzzy C Means Clustering and Linear Scaling-up Mapping

Yuhan Wu,Joonhyeon Jeon 한국통신학회 2018 한국통신학회 학술대회논문집 Vol.2018 No.1

The vast majority of medical images (CT, MRI) have a common characteristic of low contrast and poor details. Conventional enhancement techniques histogram equalization is difficult to achieve a satisfactory effect to the medical images. In this paper, an effective method is presented for improving the visual quality of the medical image. The basic idea of the proposed method is to extract important representative pixels by using the fuzzy c means clustering (FCM) algorithm, and then, the extracted representative pixels are transformed through a new intensity distribution by using a designed algorithm called linear scaling-up mapping function. The results show that the proposed method provides an excellent performance for the high contrast and rich detail features of medical images.

일반화된 라그랑지 다항식을 사용하는 FIR 하프밴드 필터 설계

봉정식(Jeongsik Bong),전준현(Joonhyeon Jeon) 대한전자공학회 2013 전자공학회논문지 Vol.50 No.10

일반적으로 최대평탄 하프밴드 필터들은 다른 필터들에 비해 넓은 주파수 영역을 가지고 있다. 이것은 필터의 주파수 응답을 직접적으로 제어하기 위한 필터 차수의 여분이 없이 단지 z =±1에서 최대 가능한 제로 수를 갖도록 설계된 것으로 독립된 파라미터가 없기 때문이다. 본 논문에서는 천이 대역폭 직접 제어가 가능한 FIR 하프밴드 필터들의 설계를 위한 새로운 방법을 제안하였다. 제안된 방법은 필터의 0번째 계수인 h0를 파라미터화한 일반화된 라그랑지 하프밴드 다항식(g-LHBP)을 기반하고 있으며, h0를 제어함으로써 요구되는 주파수 응답을 갖는 필터를 설계하는 방식이다. 이때 h0는 g-LHBP 재귀관계의 이론적 분석을 통하여 천이대역의 경사도 파라미터로 모델링하였다. 또한, 이 방식은 요구된 필터 특성(:천이대역의 경사도와 대역 평탄도 사이의 균형) 선택과 관련된 설계 파라미터들(:필터 계수들)의 직접적인 계산을 위한 명확한 공식을 제공한다. 설계예시들은 제안된 방식이 최대평탄 하프밴드 필터들 보다 상대적으로 날카로운 천이대역 경사도를 가진 하프밴드 필터의 설계에 적합한 솔루션임을 보여준다. Maximally flat (MAXFLAT) half-band filters usually have wider transition band than other filters. This is due to the fact that the maximum possible number of zeros at z = ±1 is imposed, which leaves no degree of freedom, and thus no independent parameters for direct control of the frequency response. This paper describes a novel method for the design of FIR halfband filters with an explicit control of the transition-band width. The proposed method is based on a generalized Lagrange halfband polynomial (g-LHBP) with coefficients parametizing a 0-th coefficient h0, and allows the frequency response of this filter type to be controllable by adjusting h0. Then, h0 is modeled as a steepness parameter of the transition band and this is accomplished through theoretically analyzing a polynomial recurrence relation of the g-LHBP. This method also provides explicit formulas for direct computation of design parameters related to choosing a desired filter characteristic (by trade-off between the transition-band sharpness and passband & stopband flatness). The examples are shown to provide a complete and accurate solution for the design of such filters with relatively sharper transition-band steepness than MAXFLAT half-band filters.

헤르미트 보간법을 이용한 새로운 SOC 다항식

정지흥(Jiheung Jung),전준현(Joonhyeon Jeon) 大韓電子工學會 2011 電子工學會論文誌-SC (System and control) Vol.48 No.1

본 논문에서는 저전류 충방전용 배터리의 SOC(Storage of Charge)을 구하기 위하여 헤르미트 보간법을 이용한 새로운 SOC 다항식을 제안하였다. 또한 SOC 다항식의 계수들을 직접 구할 수 있는 일반 공식이 제안되었다. 실험한 결과, 제안된 방식이 기존의 볼츠만(Boltzmann) SOC 방정식보다 실측 SOC에 정확하게 근사됨을 알 수가 있었으며, 계산적으로도 효율적인 솔루션임이 입증 되었다. This paper provides, through the use of Hermite Interpolation, a new polynomial for Storage of Charge(SOC) solution of the low-power-battery. It also gives a general formula which permits direct and simple computation of coefficients of the proposed polynomial. From the simulation results based on real SOC, it is shown that this new approach is more accurate and computationally efficient than previous Boltzmann's SOC. This solution provides a new insight into the development of SOC algorithm

Effect of a bromine complex agent on electrochemical performances of zinc electrodeposition and electrodissolution in Zinc–Bromide flow battery

Kim, Miae,Yun, Deokhee,Jeon, Joonhyeon Elsevier Sequoia 2019 Journal of Power Sources Vol. No.

<P><B>Abstract</B></P> <P>To stabilize bromine during charging in zinc-bromide flow batteries, bromine-complexing agent is typically used as a supporting material in electrolyte. This paper describes the influences of the bromine-complexing agent on the electrochemical performances of the zinc deposition and dissolution process during charge and discharge. The surface morphologies before and after the zinc electrodissolution process are compared when using 1-Ethyl-1-methyl-pyrrolidinium bromide as a bromine-complexing agent in electrolyte, and the several measurements including surface chemical analysis are also performed in conjunction with the charge–discharge cell tests. Experimental results show that employing 1-Ethyl-1-methyl-pyrrolidinium bromide in electrolyte, through the formation of an electrostatic shield of 1-Ethyl-1-methyl-pyrrolidinium cations in-and-around the zinc dendrite during charging, provides powerful and effective effects yielding the uniformly flat formation of zinc as well as the prevention of zinc-dendrite growth. It also appears that the diffusion of 1-Ethyl-1-methyl-pyrrolidinium bromide on electrodeposited zinc produces not only two type morphologies of a melting-slurry agglomerate and a furrow ripple but also the change of chemical elemental composition, resulting in higher redox reaction reversibility and activity. Consequently, these results indicate that the propagation of zinc dendrite is mostly controlled by the diffusion rate of the 1-Ethyl-1-methyl-pyrrolidinium species on the zinc metallic surface.</P> <P><B>Highlights</B></P> <P> <UL> <LI> MEP∙Br in anolyte has a special effect on zinc deposition in ZnBr<SUB>2</SUB> flow battery. </LI> <LI> MEP cations lead to forming a electrostatic shield to prevent zinc dendrite growth. </LI> <LI> MEP∙Br(C<SUB>7</SUB>H<SUB>16</SUB>NBr) provides a change in two-shape morphologies of electrodeposited zinc. </LI> <LI> Overall discharge capacities are 35.77% higher than the pristine one. </LI> <LI> Performance potentially leads to 16.65% higher current efficiency. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>