• 한국소음진동공학회논문집
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• 제21권3호
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• pp.227-233
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• 2011

The ultrasonic guided wave phased array using magnetostrictive patch transducers is proposed. The magnetostrictive transducer has received much attention because it is cost-effective and capable to generate ultrasonic waves with a simple configuration. However, it has not been used for ultrasonic guided wave phased array applications until now. In this paper, we propose a magnetostrictive transducer based phased array system consisting of a multi-channel function generator, power amplifiers and Lamb wave magnetostrictive transducers. To check the performance of the ultrasonic guided wave phased array, several Lamb wave focusing experiments were carried out in an aluminum plate. The results demonstrated the capability of the developed array to focus the Lamb waves at specific target points.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2001년도 ICCAS
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• pp.65.3-65
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• 2001

In order to apply for pickling line in cold rolling process, a high power magnetostrictive ultrasonic transducer was developed. The transducer is expected to overcome the shortcomings of conventional high power ultrasonic transducers. The transducer consists of Fe-Co-V alloy sheets for the magnetostrictive material, an ultrasonic horn made of Hastelloy to withstand acid solution, and electric driving circuit. In the development, the transducer was designed with the theoretical and numerical methods such as finite element method, and was characterized with experimental water tanks. The developed transducers turned out to be able to generate the sound pressure up to 20,000 Pa, and to be suitable for application ...

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2005년도 추계학술대회논문집
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• pp.856-859
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• 2005

The OPMT(Orientation-adjustable Patch-type Magnetostrictive Transducer) was proposed as a tool for generating and measuring the ultrasonic Lamb wave in plate type structures. This sensor has a lot of new features compared to the traditional piezo-type ultrasonic transducers. As an example, it does not need any kind of wiring for lunching or measuring ultrasonic waves. But it has also definite limitation for practical usage as a nondestructive testing tool in that it cannot help rotating the direction of ultrasonic wave manually. The idea for 'scanning OPMT' is proposed in this respect. Two kinds of basic ideas for rotating the wave direction not manually but electrically are proposed. The fabrication of the transducer and the testing for Identifying the primary characteristics are done for one of the proposed transducers. The results says that there are the possibilities as a new tool for NDE in that the proposed transducer follows well the characteristics of the traditional OPMT. But there are also the 1imitations to overcome.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2009년도 춘계학술대회 논문집
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• pp.691-692
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• 2009

• 한국소음진동공학회논문집
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• 제15권1호
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• pp.81-86
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• 2005

In this work, we propose a new ultrasonic damage inspection method in plate structures. The proposed method employs an OPMT(orientation-adjustable patch-type magnetostrictive transducer) in order to make the ultrasonic waves directed to a specific target point. For experiments, virtual grid points were set up at every 50 mm in an aluminum plate and two OPMTs were used for inspection. If there exists a crack in a plate, the reflected Lamb wave from the crack is measured in addition to the direct waves from the transmitting transducer to the receiving transducer.

• 한국소음진동공학회논문집
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• 제20권12호
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• pp.1200-1209
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• 2010

The main subject of this paper is to develop analytic method with which output power or sensitivity variations of a magnetostrictive ultrasonic transducer can be estimated with no aid of experiments. After the bias magnetic field deployed over the patch is calculated using finite element analysis for magnetostatics, the representative value is extracted by averaging these field values. The operating point on the characteristic curve for magnetostriction is identified by this value and then the output performance is calculated from it. It is verified that the results from this simple model match well with those of its experimental version and some limits of this modeling technique are also considered.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2004년도 추계학술대회논문집
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• pp.423-427
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• 2004

In this work, we propose a new ultrasonic damage inspection method in plate structures. The proposed method employs an OPMT (Orientation-adjustable Patch-type Magnetostrictive Transducer) in order to make the ultrasonic waves focused on the specific target point. For experiments, virtual grid points were set up at every 50 mm in an aluminum plate and two OPMTs were used for inspection. If there exists a crack in a plate, the reflected Lamb wave from the crack is measured in addition to the direct waves from the transmitting transducer to the receiving transducer.

• 비파괴검사학회지
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• 제28권2호
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• pp.205-210
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• 2008

파이프라인의 원거리 초음파검사를 위한 자왜 스트립형의 비틀림 모드 도파 변환기에 널리 사용되는 니켈 스트립과 철 코발트합금 스트립의 자기이력곡선을 측정하고 스트립의 자기적 특성이 변환기의 감도에 미치는 영향을 분석하였다. 최적화된 철 코발트합금 변환기의 감도는 니켈 변환기의 그것보다 약 30 배 정도로 우수하였다. 이는 두 자왜물질의 잔류자화 및 보자력의 차이에 주로 기인함이 밝혀졌다.

• 비파괴검사학회지
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• 제28권5호
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• pp.416-420
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• 2008

전자기음향변환기 분야에서는 나선형 RF 코일이 솔레노이드 코일보다 훨씬 널리 사용되고 있다. 그러나 실린더 구조물의 원거리 초음파검사용 자왜 스트립 도파변환기 분야에서는 솔레노이드 코일이 주로 사용되어왔다. 이는 아마도 낮은 주파수의(즉, 치수가 큰) 나선형 코일의 제작의 어려움에 기인하는 것 같다. 본 논문에서는 FFC(flexible flat cable)로 나선형 코일 자왜 스트립 도파변환기를 제작하는 방법을 기술한다. 기존의 솔레노이드 코일 변환기와의 비교실험을 통하여 나선형 코일 변환기가 훨씬 우수한 성능(감도, 신호-대-잡음 비, 도파방향조정능력)을 갖는다는 것을 실증한다.

• 비파괴검사학회지
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• 제31권3호
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• pp.278-286
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• 2011

The on-line monitoring for the wall thinning in secondary system has been considered one of main issues for the safety of nuclear power plants. To establish the on-line monitoring technique for the pipe wall thinning, the development of the ultrasonic transducer working in high-temperature is very important. In this investigation, the magnetostrictive transducer is concerned for high temperature condition up to $300^{\circ}C$. The magnetostrictive transducer has many advantages such as high working temperature, durability, cost-effectiveness, and shear waves, most of all. A thin Fe-Co alloy patch whose Curie temperature is over $900^{\circ}C$ was employed as a ferromagnetic material for magnetostriction. Wave transduction experiments in various temperature were carried out and the effect of bias magnets was considered together with the dry coupling performance of the transducer. From experimental results, consequently, it was found that the magnetostrictive transducer works stable even in high temperature up to $300^{\circ}C$ and can be a promising method for the on-line monitoring of the wall thinning in nuclear power plants.