• Proceedings of the KSR Conference
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• 2005.05a
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• pp.397-402
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• 2005

The NDT(Non-Destructive Testing) is valid for the defect detection of rolling stocks because it can be used to detect the defect in many invisible parts. For example, fatigue cracks are initiated in press fit parts that suffer from fretting fatigue damage such as the wheel seat and the NDT technique can detect those cracks. But the conventional ICFPD method can not apply to detect such cracks in press fit parts of the axle by some technical problems. In this study, we have introduced the new concept ICFPD method that can be applied in press fit parts of the axle. And we have shown the basic techniques of FEM about the new concept ICFPD method.

• Journal of the Korean Society for Nondestructive Testing
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• v.3 no.1
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• pp.12-18
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• 1983

This paper describes the procedures and results of an acoustic emission testing performed during hydrotest of spherical pressure vessel for propane storage. A computer based multi-channel real time monitoring and source location analysis AET-4900 system was used for AE testing. The vessel was extremely quiet throughout the entire test run and especially 6 to $14.5kg/cm^{2}$, it is normal operating pressure range. After exceeding $14.5kg/cm^{2}$, one of the 20 sections showed the most event in any one section 11 total but there were scattered at different locations. In order to confirm the events seen in horizontal weld line of that section, proof testing was performed with ultrasonics and radiography.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.11
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• pp.943-950
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• 2008

A novel nondestructive testing (NDT) system, which is able to detect a crack with high speed and high spatial resolution, is urgently required for inspecting small cracks on express train wheels. This paper proposes a high speed scan type magnetic camera, which uses the multiple amplifying circuits and the crack indicating pulse output system. The linearly integrated Hall sensors are arrayed in parallel, and the Hall voltages from each sensor in the scanning direction are obtained and amplified. High-speed NDT can be achieved by using the exclusive analog-digital converter and micro-processor because the ${\partial}\;V_H/\;{\partial}$ x value, which provides the most important crack information, can be obtained by buffering and calculating. The effectiveness of the novel method was verified by examine using cracks on the wheel specimen model.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.52 no.10
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• pp.475-483
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• 2003

In this paper, dynamic characteristics of the magnetic flux leakage(MFL) type non-destructive testing(NDT) are analyzed. Effects of a sensor speed in MFL PIG system and remanent magnetization of the gas pipeline are analyzed by using 3 dimensional nonlinear finite element analysis including eddy current and hysteresis characteristics. Results show that the speed of the sensor reduces the magnitude of the sensing signals where as the hysteresis of the pipeline distorts the sensing signals.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1996.11a
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• pp.245-248
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• 1996

In this study, piezoelectric transducers were designed and manufactured using PZT-5A which had relatively high electromechanical coefficient, NDT system was developed with was able to inspect automatically using stepping motors, PC-Lab, and PC-Scope The optimum design conditions for NDT were presented and verified comparing PZT-5A probes with comercial probes. It was proved with comercial probes. It was proved by simulation and experiments that Epoxy is good as material of matching and backing layers. The envelope was reduced 60% with matching layer and 76% with matching and backing layer. NDT was successfully carried out for aluminum test pieces. Distance error of PZT-5A probe was 2.8%.

• Journal of the Korean Society of Safety
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• v.16 no.4
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• pp.29-38
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• 2001

The purpose of this paper is to evaluate the structural integrity of a reactor pressure vessel subjected to the pressurized thermal shock(PTS) during the transient events, such as main steam line break(MSLB) and small break loss of coolant accident(SBLOCA). For postulated surface or subsurface cracks, variation curves of stress intensity factor are obtained by using the three different methods, including ASME section XI code anlysis, the finite element alternating method and the finite element method. From the stress intensity factor curves, the maximum allowable nil-ductility transition temperatures(RT/NDT/) are determined by the tangent criterion and the maximum criterion for various crack configurations and two initial transient events. As a result of the analysis, it is noted that axial cracks have smaller maximum allowable RT$_{NDT}$ values than same-sized circumferential cracks for both the transient events in the case of the tangent criterion. Axial cracks have smaller RT$_{NDT}$ values than same-sized circumferential cracks for MSLB and circumferential cracks have smaller values than axial cracks for SBLOCA in the case of the maximum criterion.

• Electrical & Electronic Materials
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• v.10 no.2
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• pp.119-125
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• 1997

In this study, piezoelectric transducers were designed and manufactured using PZT-5A which had relatively high electromechanical coefficient, nondestructive testing system was developed which was able to inspect automatically using stepping motors, PC-Lab, and PC-Scope. The optimum design conditions for NDT were presented and verified comparing PZT-5A probes with comercial probes. It was proved by simulation and experiments that Epoxy is a good material as matching and backing layers. The envelope was reduced 60% with matching layer and 76% with matching and backing layer. NDT was successfully carried out for aluminum test pieces. Distance error of PZT-5A probe was 2.8%.

• Nuclear industry
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• no.4 s.4
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• pp.35-35
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• 1978

• Nuclear industry
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• no.4 s.4
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• pp.41-49
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• 1978

• The Journal of the Acoustical Society of Korea
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• v.5 no.1
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• pp.35-40
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• 1986

본 연구는 펄스 반사법을 이용하여 금속 재료 단면의 영상을 얻는데 그 목적이 있다. 기존의 탐 상기는 대부분 A - 스캔 방식으로 결과를 전시하여 검사자가 직접 CRT 상에 나타난 결과를 판독해야 하므로 숙련자라 하더라도 어느정도 오차가 수반되며 판독에 시간이 요하는 등 불편이 따른다. 본 연구 에서는 판독 과정을 자동화함으로써 정확도와 검사 속도를 개선하였으며 탐촉 지점은 스텝핑모터를 이 용하여 일정 간격으로 제어하였다. 도 탐상 결과를 B-스캔 방식으로 영상 처리함으로써 재료 단면의 상 태 파악을 용이하게 하였다.