반사형 음향 현미경을 이용한 비파괴 검사 기술에 관한 연구

문건,고대식,김장권,전계석,Moon, Geon,Ko, Dae-Sik,Kim, Jang-Gwon,Jun, Gye-Seok 한국음향학회 1987 韓國音響學會誌 Vol.6 No.3

본 논문에서는 반사형 음향 현미경의 반사응답 특성인 V(z)현상을 고찰하고 이 현미경을 이용한 새로운 형태의 비파괴 검사 기술을 제시한다. 10원 주화, 알루미늄, 집적회로 소자, 그리고 kevlar-epoxy 등을 샘플로서 선택하고 중심주파수 3 MHz의 음향 현미경을 focused mode 및 defocused mode에서 동작시켜 실험하였다. 이 과정에서 음향 현미경의 분해능은 $500\mu m$로 나타났고 샘플의 표면 및 그 내부에 존재하는 결함은 검출되어 이를 영상화하였으며 샘플에 대한 영상의 콘트라스트 변화는 V(z)현상과 잘 일치함을 보였다. In this paper, the characteristic response of reflected signals of acoustic reflection microscope, V(z) phenomenon, has been studied and a new type of NDE technique has been presented. 10 Won coin, aluminium, IC component, and kevlar-epoxy samples have been used for the experiment of NDE and the acoustic microscope operating at a center frequency of 3 MHz has been used in the focused or defocused mode of operation. In experiment, it has been shown that the acoustic microscope has the resolution of $500\mu m$ and the defects present on the surface and near surface of samples have been detected by acoustic transducer and imaged on a monitor, and the variation of the contrast of image for samples has been in good agreement with V(z) phenomenon.

ANFIS 기반의 유황별 조건부 댐 유입량 예측기법 개발 및 평가

문건호,김선호,배덕효,Moon, Geon-Ho,Kim, Seon-Ho,Bae, Deg-Hyo 한국수자원학회 2018 한국수자원학회논문집 Vol.51 No.7

본 연구에서는 ANFIS 기반의 유황별 댐 예측유입량 산정 기법(Flow regime-based ANFIS Dam Inflow Prediction, FADIP)을 개발하고, 이를 단순 ANFIS 기반 댐 예측유입량 산정 기법(ANFIS Dam Inflow Prediction, ADIP)과 비교 평가하였다. 대상유역은 국내 주요 다목적댐인 충주댐 유역과 소양강댐 유역을 선정하였으며, 입력자료로 댐 유입량, 강수량, 장기기상예보 자료를 사용하였다. 모델의 훈련 및 보정기간으로 충주댐 유역은 1987~2010년, 소양강댐 유역은 1984~2010년을 선정하였다. 검정기간은 두 유역 모두 2011~2016년을 활용하였다. 훈련 및 보정결과 FADIP는 ADIP에 비해 평수기, 저수기에 훈련이 개선되는 것으로 나타났다. 검정결과 ADIP는 통계모델의 학습방법 특성상 일반적인 사상에 학습이 이루어져, 저수기에 예측성이 떨어지는 것으로 나타났다. 반면 FADIP는 ADIP에 비해 전기간의 정확도가 향상되었으며, 특히 평수기와 저수기에 예측성이 우수하였다. 따라서 FADIP는 다목적댐 이수관리에 활용성이 높을 것으로 판단된다. Flow regime-based ANFIS Dam Inflow Prediction (FADIP) model is developed and compared with ANFIS Dam Inflow Prediction (ADIP) model in this study. The selected study area is the Chungju and Soyang multi-purpose dam watersheds in South Korea. The dam inflow, precipitation and monthly weather forecast information are used as input variables of the models. The training and validation periods of the models are 1987~2010 for Chungju and 1984~2010 for Soyang dam watershed. The testing periods for both watersheds are 2011~2016. The results of training and validation indicate that FADIP has better training ability than ADIP for predicting dam inflow in normal and low flow regimes. In the result of testing, ADIP shows low predictability of dam inflow in the low flow regime due to the model tuning on all flow regime together. However, FADIP demonstrates the improved accuracy over the entire period compared to ADIP, especially during the normal and low flow seasons. It is concluded that FADIP is valuable for the prediction of dam inflow in the case of drought years, and useful for water supply management of the multi-purpose dam.

마이크로 프로세서를 이용한 CW송신 자동화 시스템

文建,金圭煥 군산대학교 1985 群山水産專門大學 硏究報告 Vol.19 No.3

In this paper, we described as to automatization on CW-transmission being mainly used in the maritime communication nowadays. The experimental results by using the edited programs and the developed interface hardware showed the excellent effectivity and accuracy. The CPU-6502 micro-processor was used in this system. It was proved that CW can be transmitted with good stability on the high speed more than 500CPM (characters per minute). We found that this system is very useful and effective and also save the the educational time of the students who are training the CW-morse code on keying and receiving skill.

비파괴검사에 사용되는 음향현미경 렌즈의 설계와 분해능 해석

文建 군산대학교 1986 群山水産專門大學 硏究報告 Vol.20 No.3

It has been necessary during the course of research to develop several new types of transducer for nondestructive testing. One of the best transducers is the scanning acoustic microscope using the acoustic lens. Acoustic microscope can display small opaque material or internal defects of solids. In this paper, I showed design method of acoustic lens and analyzed spherical aberration and diffraction effect which are very important factors in resolution of acoustic microscope.

Wiener 필터를 이용한 물체표면 음향영상의 품질향상

문건 濟州大學校工科大學産業技術硏究所 1996 尖端技術硏究所論文集 Vol.7 No.1

중심주파수 3Mhz의 구면형 음향변환자를 설계하여 음향영상 시스템을 구성하여서 100원 짜리 동전의 음향영상 데이터를 수신한 후에 Wiener 필터 방식을 적용하여 음향영상신호를 개선하여 잡음이 제거된 영상을 구현하였다. 여기서 잡음을 제거하기 위하여 사용한 Wiener 필터방식은 신호와 임펼스 응답신호를 컨벌루숀하여서 잡음신호와는 구별된 수 있도록 하는 방식으로 2차원 영상에 적용한 경우 매우 좋은 결과를 얻을 수 있었다. 음향신호에서 많이 나타나는 영상신호 이외의 간섭잡음 및 충격성 잡음을 제거하는 우수성을 구성한 시스템을 이용한 실험결과로서 확인하였다. 그러나 3차원 적인 영상검출 특히 고체내부의 결함검출을 위한 비파괴 검사에서 발생하는 복잡한 간섭잡음에 대하여 Wiener 필터방식을 적용하는 방안을 연구하여 더 발전해 나아가야 할 것이다. Although acoustic image is an effective and powerful method for image of materials, the technique is limited by the blurring and distortion introduced by limits of the image system. Therefore, some method of image-signal processing is essential to improve and restore the acquired images and to provide a qualitative improvement of the image evaluation process. The Wiener filtering method is one such proven method of image-signal restoration. This paper discusses the implementation of a Wiener filter in two dimensional application for image processing. Theoretical aspects of Wiener filter are briefly discussed. Results of processing acoustic signal and images acquired from coin samples are provided, also compared the methods and results between non-using Wiener filter and using Wiener filter.

음향파를 이용한 금속 부식상태 판별에 관한 연구

문건 제주대학교 산업기술연구소 1999 尖端技術硏究所論文集 Vol.10 No.2

On this study, constructed the reflective acoustic detecting system using 15MHz acoustic transducer. The most difficult problem in metal substance is to discriminate the corrosion state using none destructive method. As the test samples, the six 100 won coins which are issued on the different years are used. The experimental results showed the distinct difference among the coin's acoustic signals accorded to its issued years. I catches the common regulation in acquisited acoustic signals and convinced this technique to be very useful in corrosion discrimination of the metal substances on none destructive testing.

ANFIS를 활용한 댐 유입량 예측기법 개발 및 평가

문건호(Moon, Geon-Ho),김선호(Kim, Seon-Ho),배덕효(Bae, Deg-Hyo) 대한토목학회 2017 대한토목학회 학술대회 Vol.2017 No.10

한계레벨 가변방식에 의한 음향영상 분리검출

문건 제주대학교 산업기술연구소 2000 尖端技術硏究所論文集 Vol.11 No.1

본 연구에서는 15 MHz 의 음향 변환자를 사용한 C-스캔 반사형 음향시스템을 구성하였다. 음향영상이 동일축에 겹쳐있는 경우에 영상검출은 매우 어렵다고 알려지고 있다. 본 연구에서는 펄스 게이팅(pulse gating) 방식으로 얻어진 음향신호의 한계레벨을 가변 하는 기법을 사용하여 동일 축 상에 매우 근접하게 존재하는 음향영상을 분리 검출하는 방식을 제시하였다. 실험 샘플로는 집적회로를 사용하였고. 샘플 집적회로로부터 반사 되돌아온 음향신호 중에 강력한 표면 신호를 제거하여 내부영상을 검출하였다. 실험 결과는 다층구조에 존재하는 음향영상의 분리 가능성을 확인하였고, 이 방식은 비파괴검사 분야에서 다층영상 분리 기법에 매우 유용하게 사용될 수 있음을 확신할 수 있는 결과를 얻었다. On this study, constructed the reflective acoustic C-scanning system using 15MHz transducer. The image-detection in solid-interior in case images are existed on same perpendicular axis have been known as very difficult. This study showed the methode detecting separately the acoustic images existed very closely on the same axis by using the variation methode of threshold levels which are acquired from the time gated pulse signal. The integrated circuit(IC) is used as the experimental sample and I detected the subsurface images by using the proposed methode rejecting the strong surface image among the acoustic signals returned from the sample IC. The experimental results confirmed the possibility for the separating and detecting satisfactorily the acoustic images existed on the multiple layers and I convinced this technique to be very useful one in separating multiple layers images in none destructive testing.

탄성표면파 발진기의 가변 주파수범위 확대에 관한 연구

문건 군산대학교 1983 群山水産專門大學 硏究報告 Vol.17 No.3

Previous SAW oscillators have been designed to operate at a single frequency or over a relatively narrow range of frequencies. In this paper I describe a novel SAW oscillator which can be broaden its varriable frequencies range by phase shift circuit. SAW device is designed and consisted of two output Interdisital transducer(IDT) which are seperated by quarter of wave length. Output signal is synthesized by inductive and variable resister, and shifted its phase by external circuit. The results of this tests, the variable frequencies range could be broaden more five times than privious SAW oscillator, The short term stability is also good.

SC를 利用한 逋續近似 A/D-D/A 變換器의 變換特性에 관한 硏究

文建,金圭煥 군산대학교 1989 群山水産專門大學 硏究報告 Vol.19 No.3

Recently, the demand of A/D-D/A Converter has been increased as an I/O of analog data communication systems. But, as the most of A/D-D/A converter was built in complex circuit with many resistors, capacitors, and switches, there are necessity to reduce the cost and the number of required elements. In this paper, the operation and conversion character of simple and economic A/D-D/A converter of successive approximation type designed by using switched capacitor were studied analytically and its conversion deviation was considered experimentally. The results were as follows: 1.A/D converter of more than 6 bits could be realized by varying the time chart without the increase of logic circuit. 2.The conversion of high accuracy with linearity could be realized since it was conformed that the experimental values of conversion deviation were less than 1/2 LSB. 3.A part of the A/D converter could be used as D/A converter without changing the elements of circuit.