• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2006년도 춘계학술대회 논문집
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• pp.35-36
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• 2006

In Nd:YAG laser welding, evaluation methods of welding flaw are various. But, the method due to fume shape is difficult to classification of welding flaw. The Nd:YAG laser process is known to have high speed and deep penetration capability to become one of the most advanced welding technologies. At the present time, some methods are studied for measurement of fume shape by using high-speed camera and photo diode. This paper describes the machining characteristics of SM45C carbon steel welding by use of an Nd:YAG laser. In spite of its good mechanical characteristics, SM45C carbon steel has a high carbon contents and suffers a limitation in the industrial application due to the poor welding properties. In this study, fume shape was measured by infrared thermal camera that is non-contact/non-destructive thermal measurement equipment through change of laser generating power, speed, focus. Weld was performed on bead-on method. Measurement results are compared as two equipments. Here, two results are composed of measurement results of fume quantities due to fume shape by infrared thermal camera and inspection results of weld bead include weld flaws by ultrasonic inspector.

• 대한기계학회논문집A
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• 제20권4호
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• pp.1233-1240
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• 1996

Conventional measurement methods using ultrasonic wave or x-ray, eddy current for non-destructive testing(NDT) in nuclear power plants and other industrial plants have been utilized as the method of contact with objects to be inspected. For this reason these methods require relatively much time and inspection area is limited by the location of probe or film. But holograpic interferometry which is a non-contact optical measurement method using a coherent light source has an advantage that quantative measurement can be performed at a time. In this paper a new method using realtime holographic interfreometry and image processing for detecting internal flaws of pressure vessels is presented.

• Journal of Radiation Protection and Research
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• 제41권2호
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• pp.93-99
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• 2016

Background: Industrial X-ray CT system is normally applied to non-destructive testing (NDT) for industrial product made from metal. Furthermore there are some special CT systems, which have an ability to inspect nuclear fuel assemblies or rocket motors, using high power and high energy (more than 6 MeV) pulsed X-ray source. In these case, pulsed X-ray are produced by the electron linear accelerator, and a huge number of photons with a wide energy spectrum are produced within a very short period. Consequently, it is difficult to measure the X-ray energy spectrum for such accelerator-based X-ray sources using simple spectrometry. Due to this difficulty, unexpected images and artifacts which lead to incorrect density information and dimensions of specimens cannot be avoided in CT images. For getting highly precise CT images, it is important to know the precise energy spectrum of emitted X-rays. Materials and Methods: In order to realize it we investigated a new approach utilizing the Bayesian estimation method combined with an attenuation curve measurement using step shaped attenuation material. This method was validated by precise measurement of energy spectrum from a 1 MeV electron accelerator. In this study, to extend the applicable X-ray energy range we tried to measure energy spectra of X-ray sources from 6 and 9 MeV linear accelerators by using the recently developed method. Results and Discussion: In this study, an attenuation curves are measured by using a step-shaped attenuation materials of aluminum and steel individually, and the each X-ray spectrum is reconstructed from the measured attenuation curve by the spectrum type Bayesian estimation method. Conclusion: The obtained result shows good agreement with simulated spectra, and the presently developed technique is adaptable for high energy X-ray source more than 6 MeV.

• 지구물리와물리탐사
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• 제16권1호
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• pp.45-52
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• 2013

본 연구에서는 판상 구조물의 비파괴시험을 위한 충격응답시험기 및 운용 소프트웨어를 개발하였으며, 콘크리트 또는 아스팔트로 포장된 인도에서 충격응답 자료 취득 시험을 실시하였다. 현장 자료 취득 시험에서 개발된 시스템은 안정적으로 신속하게 충격응답반응을 측정하였다. 현장 시험 결과, 포장재 특성에 따라 동적강성, 평균운동성 등의 절대 값이 크게 변화 하였다. 또한 일부 구간에서는 포장재 또는 하부 지반의 변화를 반영하는 것으로 판단되는 값의 변화가 측정되었다. 본 연구를 통해 만들어진 시스템은 판상구조물의 상태에 대한 정보를 쉽고 빠르게 획득할 수 있을 것으로 판단된다. 본 연구에서 개발된 장비를 이용하여 조사 대상물에 대한 2차원 측정과 모니터링을 한다면, 구조물의 유지 보수에 유용한 정보를 얻을 수 있을 것으로 기대된다.

• 농업과학연구
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• 제39권4호
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• pp.603-612
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• 2012

In this research, the feasibility of non-destructive measurement technique of pungency measurement was investigated for the red-pepper powders produced in different domestic areas in South Korea. The near-infrared absorption spectra in the range of 1100 nm~2300 nm was used to measure capsaicinoids content in red-pepper powders by using a NIR spectroscopy equipped with Acousto-optic tunable filters (AOTF). Fourth three different red-pepper powders from 14 different locations were collected and separated in three different particle size (below 0.425 mm, 0.425~0.71 mm, 0.71~1.4 mm) for the spectral measurements. The partial least square regression (PLSR) models to predict the capsaicinoids content depends on particle size were developed with the measured spectra. The determinant coefficients and standard errors of the developed models for the red-pepper powders of below 0.425 mm, 0.425~0.71 mm, and 0.71~1.4 mm were in the range of 0.859~0.887 and 12.90~12.99 mg/100 g, respectively. The PLS model with the pretreatment of Standard Normal Variate (SNV) for the red-pepper powders below 1.4 mm particle size showed the best performance with the determinant coefficient of 0.844 and the standard error of 14.63 mg/100 g.

• 비파괴검사학회지
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• 제28권3호
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• pp.245-253
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• 2008

A precise description of the material is a key point to obtain reliable results when using wave propagation codes. In the case of multipass welds, the material is very difficult to describe due to its anisotropic and heterogeneous properties. Two main advances are presented in the following. The first advance is a model which describes the anisotropy resulting from the metal solidification and thus the model reproduces an anisotropy that is correlated with the grain orientation. The model is called MINA for modelling anisotropy from Notebook of Arc welding. With this kind of material model1ing a good description of the behaviour of the wave propagation is obtained, such as beam deviation or even beam division. But another advance is also necessary to have a good amplitude prediction: a good quantification of the attenuation, particularly due to grain scattering, is also required as far as attenuation exhibits a strong anisotropic behaviour too. Measurement of attenuation is difficult to achieve in anisotropic materials. An experimental approach has been based both on the decomposition of experimental beams into plane waves angular spectra and on the propagation modelling through the anisotropic material via transmission coefficients computed in generally triclinic case. Various examples of results are showed and also some prospects to continue refining numerical simulation of wave propagation.

• 보존과학회지
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• 제26권1호
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• pp.77-83
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• 2010

국내에 서식하는 지중흰개미는 목재 내부에 공동화 현상이 발생되어 붕괴가 일어나기 직전까지도 외관상 특별한 변화가 발견되지 않는다. 이러한 흰개미의 활성을 비파괴적으로 측정하는 기술은 현재 국내에 적용된 사례가 없었다. 따라서 본 연구는 극초단파 탐지 장비(Termatrac, Australia)를 이용하여 목조 문화재의 비파괴 진단 기술을 정립하고자 한다. 연구 결과, 소나무의 경우 16cm(민감도 5, 6), 느티나무와 Douglas fir의 경우 17cm(민감도 5, 6)까지 측정이 가능하여 국내 대부분의 목조 건축물에 적용이 가능할 것으로 판단되었다. 현장조사 결과 전국 목조건축물 231동 중 33.8%가 흰개미에 의한 손상을 입었으며, 7.8%인 총 18개 건물에서 흰개미 가해가 진행 중인 것을 확인할 수 있었다. 이와 같은 결과를 통해 목조 문화재의 비파괴 분석법으로서 적용이 가능할 것이라 예상된다.

• Journal of Radiation Protection and Research
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• 제35권1호
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• pp.26-33
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• 2010

비파괴검사 분야의 방사선 검사(RT) 방식은 image plate (IP)를 사용한 Computed Radiography(CR) 영상시스템의 도입에 따라 필름 방식의 아날로그 영상이 점차 디지털 영상으로 교체되고 있다. 비파괴검사에서 결함을 효과적으로 검출할 수 있는 영상의 품질은 촬영 조건, 영상획득매체, 사용 선원의 종류 및 촬영 거리, 검사체 두께등이 영향을 미친다. 본 논문에서는 비파괴 검사 분야에 적용할 수 있는 감마선원의 기본 특성을 조사하였고, FUJI사에서 개발한 CR 영상 시스템에 $^{75}Se$, $^{192}Ir$ 동위원소를 적용하여 영상을 획득하였다. 획득된 영상의 gray scale을 이미지 소프트웨어를 통해 추출한 후에 대조도 및 신호대잡음비를 계산하고 비교 분석하였다. 또한 투과도계를 이용한 비교 영상을 통하여 식별도를 분석하였다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2002년도 가을 학술발표회 논문집
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• pp.685-691
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• 2002

Air exclusion test which is the way to assess the quality of the concrete is a part destructive test for minor damaging and accurate measurement. it has been well known but the test process is complexed, so it has been well known in foreign country but it is not usable in our country. For this experiment, it analyze its special quality through the inspection for the factor which effect to the result or accuracy for the Air exclusion test, and it examine through the experiment for the Non destructive test and cylinder compressive test which is different from the air exclusion test. We suggest the suitable classified table for the domestic concrete condition through the comparative analysis against the overseas result that has been suggested before.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 춘계학술대회 논문집
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• pp.510-514
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• 2002

The 3-dimensional measuring machine by using an ultrasonic sensor is used one of the NDE(Non Destructive Examination). It is applied to the inspection of pipelines, boreholes, pressure vessel and tank, and so on. In particular when a harsh environment prohibits the use of moving mechanical parts. The 3-dimensional measuring machine by using an ultrasonic sensor, which measure 1-dimensional information and 2-dimensional information simultaneously from a target of inspection, and then reembody 3-dimensional information. So we can find the situation in progress and predict remaining life and corrosion without destructive examination. It's a point of excellence that the 3-dimensional measuring machine is portable.