소음계 자동 교정 시스템

조병모 순천대학교 공업기술연구소 1995 工業技術硏究所論文集 Vol.9 No.-

It is expected that the techniques are able to measured sound level meter automatically as soon as possible, coping with the increasing of calibration quantity for sound level meter. The error and the inconverience which are accomplished by manual calibration system will be reduced by means of automated calibration system. The purpose of this paper is to develope the automatic calibration system that be able to even the power spectrum of acoustic measurement system including a standard microphone and speaker system automatically and calibrate the spectrum of sound level meter at every calibrating frequency.

지체장애인의 정형구두 착용실태와 관련요인 분석

조병모,이형수 한국장애인재활협회 2009 재활복지 Vol.13 No.4

선형 위상 응답 특성을 갖는 빔 형성기 ( Adaptive Beamformer with Linear Phase Response )

조병모,강홍구,차일환,윤대희 대한전자공학회 1990 대한전자공학회 학술대회 Vol.1990 No.1

ON/OFF-스위치의 위치 인식 방법

조병모,이권연,손명식,Cho, Byung-Mo,Lee, Kwon-Yeon,Son, Myung-Sik 한국전기전자학회 2007 전기전자학회논문지 Vol.11 No.1

본 논문은 직렬로 연결된 스위치의 OFF-위치를 감지할 수 있는 방법을 제안한다. 각각의 스위치에는 병렬로 각기 다른 주파수 특성을 갖는 수동 소자가 병렬로 연결되어 있다. ON된 스위치에는 병렬로 연결된 수동 소자의 주파수 특성에 관계없이 평탄한 특성을 갖으며, OFF된 스위치의 경우에는 연결된 수동소자의 주파수 특성이 스위치의 양 단자에 나타난다. OFF된 스위치의 위치 인식은 직렬로 연결된 스위치의 양 단자에 백색 잡음(Maximum-Length Sequence)을 입력하고, 각각의 스위치를 OFF한 상태에서 출력 단자에서 스펙트럼을 계산하여 미리 참조 스펙트럼을 작성하고, 작성된 참조 스펙트럼과 입력 스펙트럼 간의 유사도를 계산하여 가장 근접한 참조 스펙트럼을 OFF된 스위치의 스펙트럼으로 인식한다. 이를 위한 디지털 신호처리 시스템을 설계하고, 설계된 시스템을 이용하여 스펙트럼 매칭으로 OFF-스위치의 위치를 감지한다. This paper proposes a detection method of position of OFF-switch. Each switch has the parallel path with a serial combination of passive element, its parallel path has each different frequency characteristics. Frequency characteristic of ON-switch reveals a flat spectrum irrelevant to frequency characteristic of passive element connected in parallel to its each terminal and frequency characteristic of OFF-switch reveals the same characteristic as one of passive element connected in parallel. Detection of position of OFF-switch is done by measuring the similarity of each spectrum corresponding to frequency characteristic of passive element connected in parallel to OFF-switch. The measure of their similarity is to calculate Euclidean distance between their test spectrum and reference spectrum. The spectrum with the smallest distance among reference spectrum is recognized as the spectrum of OFF-switch. The real time digital signal processing system is implemented to detect the position of OFF-switch by using spectrum matching.

개선된 FIR QMF 뱅크의 설계 방법

조병모,김영수 한국통신학회 2004 韓國通信學會論文誌 Vol.29 No.2c

A new method for design of two-channel finite-impulse response(FIR) quadrature mirror-image filter(QMF) banks with low reconstruction delay using weighting function is proposed. The weighting function used in this paper is calculated from the previous updated filter coefficients vector which is adjusted from iteration to iteration in the design of QMF banks. In this paper, passband and stopband edge frequency are used in design of QMF banks with low delay characteristic in time domain instead of specific frequency interval where the artifacts occur in conventional design method. The investigation of specific frequency interval where artifacts occur can not be required by using passband and stopband edge frequency. Some comparisons of performance are made with other existing design method to demonstrate the proposed method for QMF bank design. and it was observed that the proposed method using the weighted function and passband and stopband edge frequency improves the peak reconstruction error by 0.001 [dB], the peak-to-peak passband ripple by 0.003[dB], SNR with a white noise by 7[dB] and SNR with a step input by 32[dB], but with a reduction of the computational efficiency because of updating the weighting function over the conventional method in Ref [11]. 본 논문에서는 저지연 특성을 갖는 2 채널 FIR QMF 뱅크를 시간 영역에서 가중 함수를 이용해서 설계하는 새로운 방법을 제안한다. QMF 뱅크를 설계할 때에 본 논문에서 사용한 가중 함수는 QMF의 반복 설계 과정에서 얻어진 이전의 필터 계수 벡터를 이용하여 계산한다. 그리고 기존의 방법에서는 왜곡이 생기는 주파수 대역은 천이 대역에서 왜곡이 생기는 특정 주파수 대역을 이용하지만 본 논문에서는 통과 대역과 저지 대역 에지 주파수를 이용한다. 통과 대역과 저지 대역 에지 주파수를 이용함으로써 왜곡이 생기는 특정 주파수 대역을 조사할 필요가 없는 장점이 있다. QMF 뱅크 설계에 적용하기 위해서 제안된 방법의 성능 결과를 기존의 방법과 비교하였으며, 가중 함수와 통과 및 저지 대역 에지 주파수를 이용한 제안된 방법이 가중 함수를 계산하기 때문에 기존의 방법에 비해 연산 성능은 떨어지지만 재생 오차는 최대 0.001[dB], 통과 대역 리플은 0.003[dB] 그리고 백색 잡음에 대한 SNR은 71[dB], 스텝 입력에 대한 SNR은 32[dB] 증가했다.

M-계열 신호를 이용한 음향 임펄스 응답의 고속 측정법

조병모 順天大學校 1992 論文集 Vol.11 No.1

A method of measuring impulse response is described using Maximum-length sequence as the test input signal. The impulse response of a acoustic system from speaker (sound source) to Dummy Head ear can be determined by exciting the acoustic system with white noise, and cross-correlating the white noise input and Dummy Head ear output. In order to minimize the amount of computation required by the cross-correlation step, the acoustic system can be excited by Maximum-length sequence for the white noise input, and the cross-correlation can be performed with an algorithm based upon the Fast Hadamard Transform. A straightforward cross-correlation method would require the evaluation of approximately L² multiplications, but in this method the number of additions can be reduced to the order of L log2 L, where L is the length of the Maximum-length sequence.

Interpolation과 Decimation에 의한 음상정위 시스템의 역필터 설계

조병모,이권연 순천대학교 공업기술연구소 1996 工業技術硏究所論文集 Vol.10 No.-

Digital equalizer utilizing finite impulse response digital filters is developed with taking care to the minimum phase characteristic including all - pass phase. The HRTF(Head-Related Transfer Function) were measured with maximum - length sequences as a test signal at a sampling frequency of 35k㎐, and the impulse response were recovered by use of the fast Hadamard deconvolution algorithm. This paper proposes an efficient method of designing the crosstalk canceller and inverse filter of HRTF using interpolation and decimation method in designing the sound loalization system, which is including the method that takes the absolute value of group delay in minimum phase components.

일측 하퇴 의족 착용자의 절단단 길이에 따른 보행특성

조병모,변주남,김기순,김석산,박종 조선대학교 부설 의학연구소 1999 The Medical Journal of Chosun University Vol.24 No.1

This report studied 31 male patients who were in one hospital in Kwangju or came to a prosthesis clinic and are 15 normal control group to analyze the gait characteristics according to the stump length in the prosthesis users with the unilateral below-knee amputations. The patient group was divided into a short stump subgroup of 13 patients and a long stump subgroup of 18 patients according to the stump length, the control group was randomly sampled from 15 males who have similar age, height and weight to the experimental group. The results of analysis are summarized as follows. 1. There were no significant statistical differences of the general characteristics between patient and control groups and there was no difference of characteristics by patient groups except the mean gait distance a day. 2. Of 33 patients with amputation, 18 patients (57.8%) had phantom pain and 25 cases (80.6%) had neuroma. 3. Gait velocity, stride length of the affected side, step length of the sound side and base support among gait characteristics show a significant difference according to the stump length in the state excluding the effects of other factors (p<05) and the group with long stump showed closer gait characteristics to normal persons than those with short stumps. In conclusion, among the patients of unilateral below-knee amputations, the stump length affects the gait characteristics such as gait velocity, stride length, step and base of support and it is found that as the stump length gets longer, it shows the similar characteristics to gait characteristics of normal persons and long unilateral below-knee amputation can secure better gait characteristics.

Swedish Knee Cage 보조기 착용이 뇌성마비환자의 전반슬(Genu recurvatum)에 미치는 영향

조병모,Cho, Byeong-Mo 대한물리치료과학회 2001 대한물리치료과학회지 Vol.8 No.2

The purpose of this single subject case study was to evaluate the effectiveness of a swedish knee cage worn to prevent genu recurvatum in right spastic hemiplegic with cerebral palsy. The subject was a 6-year-old female who had right side hemiparesis with genu recurvatum on affected side for the 18 month from January 1998 to June 1999. As a result, genu recurvatum of the patient was reduced the 7 degree after the putting on the swedish knee cage.

변형된 Filtered-x LMS 알고리즘을 이용한 소음제어

조병모 순천대학교 공업기술연구소 1994 工業技術硏究所論文集 Vol.8 No.-

The Filtered-x LMS algorithm is an alternative form in active noise control system the existence of a auxiliary or error plant(path) in a conventional system has been shown to be generally degrade the performance of noise reduction. A modified form, which includes adaptive modeling process of auxiliary path in parallel using M-sequence signal, of Filtered-x LMS algorithm is proposed to widen the bounds for the convergence parameter and to improve the noise reduction. In the proposed method, the input signal to the noise controller passes through the error plant transfer function to form the noise estimate. this noise estimate is subtracted directly from the noise signal at error sensor output, yielding the error signal which is used in updating the controller coefficients. Next, the adapted coefficients is copied in noise controller to used in noise reduction process. Computer simulations have been used to compare the performance of the proposed method to that of a general Filtered-x LMS algorithm for noise attenuation. The simulation results indicate that the advantage of the proposed method over the conventional Filtered-x LMS algirithm has the wider convergence parameter because the error plant not exits, and that the noise reduction in proposed method is about 2-3dB greater for the band-limited noise input signal, but the proposed method requires a large amount of computation as compared with conventional one.