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핵연료 채널과 LIN 간격 측정을 위한 전자기 분포해석 및 원격장 와전류 신호 모델링
이동훈,정현규,정용무,허형,이윤상 한국비파괴검사학회 2004 학술대회 논문집 Vol.- No.-
Fuel channels including pressure tube(PT) and calandria tube(CT) are important components of pressurized heavy water reactor(PHWR). A sagging of fuel channel increases by heat and radiation exposure with the increasing operation time. The contact of fuel channel to liquid injection nozzle(LIN) is thus a critical issue in power plant safety. In order to solve this safety issue, the electromagnetic technique was applied to compliment the present inspection technology. Electromagnetic fields were investigated for the gap measurement between CT and LIN using FEM computer modeling. We calculated the electromagnetic fields, such as, magnetic flux density, current density near the fuel channel and checked the adaptability of RFEC technology. The RFEC Signals using the volume integral method(VIM) were simulated for obtaining the optimal inspection parameters, including frequency, inter-coil spacing, coil size and configuration. Finally, we development the remote field eddy current sensor that can CT/LIN gap measurement efficiently
원심 주조 스텐레스 강에서의 이론적 모델을 통한 Beam Skewing 영향 고찰
이삼래,이윤상,임형택 한국비파괴검사학회 1990 한국비파괴검사학회지 Vol.10 No.1
Centrifugally Cast Stainless Steel generally shows similar structure to the weld in austenitic stainless steel in the point of casting. When examining this material ultrasonically, the beam does not generally propagate straightforward but rather deviates from its original direction and this phenomenon called skewing is originally caused by anisotropic material. In order to calculate the beam skewing effect theoretically, work has been performed based on a model approach which has regarded material itself as having been composed of multi-layered columnar dendrite structure and the result was compared with the one from experiment. The result from both theory and experiment showed good correlation and ultrasonic beam showed the least skewing with around 45 degree incident angle.
교차 배열된 지르코늄관 간격 측정을 위한 전압 평면에서의 신호해석
정현규,이윤상,이동훈,허형,정용무 한국비파괴검사학회 2003 학술대회 논문집 Vol.- No.1
The eddy current(EC) signals were evaluated for gap measurement of cross aligned zirconium tubes for preventing the contact which might be the safety concern. Liquid lnjection Nozzle(LIN) tube and Calandria tube(CT) were cross-aligned horizontally and LIN could be detected by inserting the EC probe into pressure tube (PT). Signal analysis on the voltage plane was applied to describe the position and shape of possible defects using several frequencies. Test variables are lift-off, PT thickness variation, and gap variation between PT and CT All the EC measurements in the laboratory were done in variance with the gap spacings and showed the possibility to evaluate the gap between CT. and LIN tube by analyzing the signal on voltage plane. Electromagnetic technique could be a potential tool for inspecting the inter-tube gap in CANDU reactor.
5052 알루미늄 합금 레이저 용접부의 기계적 성질에 관한 연구
윤종원,이윤상,이문용,정병훈 한국레이저가공학회 2003 한국레이저가공학회지 Vol.6 No.1
5052 aluminum alloy sheets of 2mm thickness were butt welded using a continuous wave Nd:YAG laser with and without Ar shielding gas. Vickers hardness, transverse-weld tensile and bulge tests were carried out to investigate the effect of Ar shielding gas on the mechanical properties and formability of laser welds. Porosity in the weld metals was investigated using an optical microscope. Mechanical properties and formability of 5052 aluminum alloy laser welds were degraded compared to those of base metal. However, those properties were improved due to the reduced size and number of porosity when Ar shielding gas was used.
6061 알루미늄 합금 Nd : YAG 레이저 용접의 기계적 성질에 관한 연구 YAG laser welded 6061 aluminum alloy
윤종원,이윤상,이문용,정병훈 한국레이저가공학회 2003 한국레이저가공학회지 Vol.6 No.2
6061 aluminum alloy sheets were I-square butt welded using a continuous wave Nd: YAG laser. Heat inputs were varied from 54.6 to 80 J/mm for butt welding using different sets of the laser power and the weld speed. I-square butt welds were also made with and without Ar shielding gas. The effect of Ar shielding gas and heat input on the mechanical properties and formability was investigated using Vickers hardness, transverse-weld tensile and bulge test. Porosity on the weld beads and sections and hot crack on the fracture surfaces of transverse-weld tensile test specimens were investigated using optical and scanning electron microscopy. The experimental results showed that mechanical properties and formability of 6061 aluminum alloy laser welds were degraded compared to those of base metal. Mechanical properties and formability of 6061 aluminum alloy laser welds were not substantially changed when Ar shielding gas was supplied or heat inputs were varied.
중수로 핵연료채널과 인접관의 간격측정을 위한 원거리장 와전류검사 기술개발
정현규,이동훈,이윤상,허형,정용무 한국비파괴검사학회 2004 한국비파괴검사학회지 Vol.24 No.2
중수로 내부구조물 중 칼란드리아관(CT)와 액체주입노즐관(LIN)은 서로 수평으로 90도 교차되게 배열되어 있으며 원자로 내의 열, 방사선, 하중에 의해 creep 현상이 발생되어 처짐이 일어난다. 칼란드리아관은 액체주입노즐관과 동일 재료이나 운전 온도와 방사선 조사량으로 인해 액체주입노즐에 비해 상당히 열악한 조건에 노출되어 있으므로 처짐이 심각할 것으로 예상된다. 만약 두 관의 접촉이 발생되면 원전 안전성에 영향을 미칠 것이므로 인접관에 대한 접촉여부 점검은 중수로 안전현안 중 하나이다. 이러한 접촉여부를 확인하기 위하여 핵연료채널 내부로 탐촉자를 삽입하여 인접관과의 교차점에서 간격을 직접측정하기 위한 방법으로 원거리장 와전류검사(RFECT) 기술을 적용하였다. 핵연료채널 인접관인 액체주입노즐관 신호 취득시 발생 가능한 잡음 신호(두께변화, Lift-off, 수축)에 대해 체적적분법에 의한 모델링으로 조사하였고, 신호와 잡음과의 분리가능한 조건을 확인하였다. 원거리장 와전류검사 적정 조건은 민감도와 투과력 그리고 잡음신호 등을 동시에 고려하여 주파수 1kHz와 코일간격 200mm로서 결정하였다. 원거리장 와전류검사 실험 결과 칼란드리아관과 액체주입노즐관 사이의 간격 변화에 대한 신호 특성을 전압평면을 이용하여 상관관계를 도출하였다. Liquid Injection Nozzle(LIN) tube and Calandria tube(CT) in Pressurized Heavy Water Reactor (PHWR) are cross-aligned horizontally. These neighboring tubes can contact each other due to the sag of the calandria tube resulting from the irradiation creep and thermal creep, and fuel load, etc. In order to judge the contact which might be the safety concern, the remote field eddy current (RFEC) technology is applied for the gap measurement in this paper LIN can be detected by inserting the RFEC probe into pressure tube (PT) at the crossing point directly. To obtain the optimal conditions of the RFEC inspection, the sensitivity, penetration and noise signals are considered simultaneously. The optimal frequency and coil spacing are 1 ㎑ and 200 ㎜ respectively. Possible noises during LIN signal acquisition are caused by lift-off, PT thickness variation, and gap variation between PT and CT. The simulated noise signals were investigated by the Volume Integral Method(VIM). Signal analysis on the voltage plane describes the amplitude and shape of LIN and possible defects at several frequencies. All the RFEC measurements in the laboratory were done in variance with the CT/LIN gap and showed the relationship between the LIN gap and the signal parameters by analyzing the voltage plane signals.