• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2006년도 춘계학술논문 발표대회 제6권1호
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• pp.185-187
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• 2006

This study deals with characterization and the application of magnetoelasticity as a device which measures existing steel stress. Available method of measuring existing stress needs break the concrete and cut the steel bar. But Proposed method doesn't need to cut the steel bar. A successful application of magnetoelasticity depends on the linearity of the relationship between the elastic and magnetic response due to loading. To investigate the correlation between two, steel bars are loaded in tension under uniaxial loading while the magnetic reading is recorded. Results showed linearity or partial-linearity of the elastic behavior of steel bars in relation to magnetic change. In the paper, the various factors affecting the measurements are also discussed.

• 한국생산제조학회지
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• 제19권3호
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• pp.313-320
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• 2010

The magnetic abrasive polishing (MAP) process is used to achieve the nano-meter grade polishing results on flat or complicated surface. In previous study, polishing the stainless steel plate which is a non-magneto-material was tried. To polish non-magneto-materials using the MAP process was very difficult because the process was fundamentally possible by the help of a magnetic force. Therefore, it had lower efficiency than magneto-materials such as SM45C. In this study, optimization for tool geometry of the MAP was performed to improve the magnetic force between tool and workpiece. Moreover, a permanent magnet was installed below the non-magneto-material to improve the magnetic force. And then the design of experiments was carried out to evaluate the effect of the MAP parameters on the polishing results.

• 대한기계학회논문집A
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• 제35권4호
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• pp.401-407
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• 2011

본 연구에서는 AZ31B 마그네슘 합금 평판 연마에 제 2세대 자기연마공정을 적용하고 실험계획법을 통해 공정인자들의 특성을 평가하였으며, 2차 반응표면모델을 이용한 표면거칠기 예측모델을 개발하였다. 비자성체 재료의 기존 자기연마 공정에서는 재료의 표면에서 자기력이 낮아 표면거칠기의 향상에 효율이 낮은 단점을 가진다. 이를 보완하기 위하여 전자석 배열을 이용한 자기력 테이블을 자기연마 공정에 적용하여 비자성체 표면의 자기력을 향상시킬 수 있었다. 이러한 시스템을 제 2세대 자기연마라 일컫고, 실험계획법에 따른 공정 인자 평가 결과, 자기력 테이블의 전자석 세기가 AZ31B 평판의 표면 거칠기 향상에 가장 큰 영향을 가지고 있음을 확인했다. 또한 자기력 테이블과 공구의 회전속도에 따른 반응표면모델을 개발함으로써 마그네슘 자기연마 공정의 효율성을 높일 수 있었다.

• Steel and Composite Structures
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• 제19권3호
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• pp.601-614
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• 2015

The Metal Magnetic Memory (MMM) method is a non-destructive testing method based on an analysis of the self-magnetic leakage field distribution on the surface of a component. It is used for determining the stress concentration zones or any irregularities on the surface or inside the components fabricated from ferrous-based materials. Thus, this paper presents the MMM signal behaviour due to the application of fatigue loading. A series of MMM data measurements were performed to obtain the magnetic leakage signal characteristics at the elastic, pre-crack and crack propagation regions that might be caused by residual stresses when cyclic loadings were applied onto the A283 Grade C steel specimens. It was found that the MMM method was able to detect the defects that occurred in the specimens. In addition, a justification of the Self Magnetic Flux Leakage patterns is discussed for demonstrating the effectiveness of this method in assessing the A283 Grade C steel under cyclic loadings.

• 한국자기학회지
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• 제10권6호
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• pp.302-309
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• 2000

박강판의 내부에 존재하는 개재물성 결함을 검사하기 위해 누설자속법을 이용하여 탐상하는 시스템을 개발하였다. 연자성 코어의 보자력을 이용한 차등형 플럭스게이트 자력계를 제작하였다. FEM 소프트웨어를 이용하여 전자석을 설계하였으며, 3축 이동이 가능한 누설자속탐상장치를 제작하여 냉연강판을 검사한 결과 개재물성 결함을 검사학 수 있음을 알았다. 누설자속값을 디지털화하여 2차원 이미지로 처리한 결과 냉연강판에 존재하는 개재물성 결함 이외의 결함을 일부 구분할 수 있음을 알았다.

• 한국생산제조학회지
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• 제20권3호
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• pp.304-309
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• 2011

A monitoring system for magnetic abrasive polishing process is necessary to ensure the polishing products the high quality and integrity. Acoustic emission (AE) signal is known to reflect the material removal phenomena in other machining processes. In a case of the magnetic abrasive polishing of non-magnetic materials, application of AE method is very difficult because of lower machining force on the surface of workpiece and the level of AE signal is extremely lower. In this study, AE sensor-based monitoring system is applied to the magnetic abrasive polishing. The relation between the level of the AE RMS and the surface roughness during the magnetic abrasive polishing of magnesium alloy steel is investigated.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2008년도 제39회 하계학술대회
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• pp.625-626
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• 2008

The magnetic domain-refining techniques such as ball scratching, laser irradiation and plasma have been developed to reduce the domain wall spacing and thus iron losses in Fe-3%Si grain-oriented silicon steels. In view point of magnetic properties, it was supposed that the locally residual stresses change the magnetoelastic energy of the material and thus the spacing between $180^{\circ}$ domain walls decreases in order to reduce the magnetostatic energy. The effect of laser irradiation on iron loss and magnetostriction reduction for Fe-3%Si grain-oriented steel were investigated. Since the local tensile stresses were induced at the surface of Fe-3%Si steel by the laser irradiation, the minimum iron loss caused by reducing eddy current loss was obtained in spiete of the decrease of permeability by hindering eddy current loss was obtained in spite of the decrease of permeability by hindering the domain wall movement around the induced stress field. Furthermore, the laser treated 3%Si steel has lower magnetostriction as compared to non laser-treated steel and is less sensitive to applying pre-stresses due to the volume reduction of $90^{\circ}$ domain in materials.

• Journal of Magnetics
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• 제21권2호
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• pp.209-214
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• 2016

This paper analyzes the magnetic property according to the machined shape of steel material with non-oriented silicon steel (50PN470/50A470), that is most commonly used in the design of electrical equipment. Toward this end, specimens were produced and divided into Bar-Specimen (Epstein Frame Tester) and Ring-Specimen (Toroidal Ring Tester). The characteristics of the electrical Silicon steel were measured using the instruments solely dedicated to measuring each specimen. The core loss of the Bar-Specimen, which is commonly used, was found to be less than that of the Ring-Specimen. This is a very important design factor in achieving the objectives of improving the product efficiency and predicting the performance of electrical equipment. It serves as a critical point of view in order to reduce the error between design value and product value. A comparative analysis was conducted regarding various characteristics (Hysteresis, B-H characteristic, Iron loss, Minor loop, Coercive force, Residual magnetic flux density, etc.) of the electrical silicon steel considered in the design of the electrical equipment according to the specimen.

• 한국구조물진단유지관리공학회 논문집
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• 제23권7호
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• pp.129-136
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• 2019

본 연구에서는 강판 손상 진단을 위하여 누설자속 기법을 적용하고, 신호 기반으로 신호의 이미지화 기법에 대해 연구를 실시하였다. 누설자속 신호의 이미지화를 위해 다른 두께를 가지는 강판시편을 준비하였고, 각 시편에 똑같은 위치에 6가지 깊이의 손상을 인공적으로 가공하였다. 홀센서와 Yoke를 이용한 센서헤드를 제작하여 강판시편을 자화시킴과 동시에 누설자속 신호를 계측하였다. 센서로부터 수집된 자속신호의 노이즈 제거 및 이미지 해상도를 높이기 위하여 여러 신호처리 과정을 거쳤으며, 각 손상부로부터 계측된 누설자속 신호의 분석을 위해 각 채널별로 P-P value를 분석하였다. 위의 신호처리 및 분석을 바탕으로 누설자속 신호를 이미지로 변환시켰다. 이를 통해 누설자속 신호 기반 강판 손상의 이미지화로 손상을 한눈에 파악하는 것이 가능하였다.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2009년도 제40회 하계학술대회
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• pp.851_852
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• 2009

Shrink fitting which is assembling process to fix stator core on the motor frame is widely used at the mass production line of motors because of cost and productivity. This process produces compressive stress on a stator core, which causes negative effect for example, core and copper losses on motor performance. Magnetic properties of electrical steel are effected by both compressive and tensile and thermal stresses. Electromagnetic field analysis is considered one of the effective process since one can predict motor performance including core loss precisely. This method can consider non linear magnetic property with magnetic saturation which is typical electrical steel behavior. However this method is strongly depended on non linear magnetic data, one may have different calculation result whether considering mechanical stress or not. This study describes magnetic field analysis of a motor considering mechanical stress from shrink fitting. Analysis results are compared with each stress-free and stressed condition.