연강 판재의 맞대기 용접에서 아크에 작용하는 자기력의 해석

배강열,Bae Kang-Yul 대한용접접합학회 2005 대한용접·접합학회지 Vol.23 No.4

Arc blow being occurred by Electro-Magnetic force(EMF) during the electric arc welding prevents the formation of a sound weldment. In this study, the effects of arc position, groove size, tack weld and base plate on the EMF in a butt-joint welding of mild steel plate are analyzed by a computer simulation based on the finite element method. The EMF can be numerically identified to be caused by a difference of the magnetic flux-density between ahead of and behind the arc in case that the workpiece locates asymmetrically around the uc. When there exists an air gap of groove ahead of the arc in the welding direction, the similar magnetic force has been producted regardless of the arc position and the gap size. The tack weld alleviates the magnetic force to about one fourth at the finish end of the workpiece. The magnetic force can be also significantly reduced with the base plate to about one fifth at the start end of the workpiece containing a tack weld.

연삭기용 직각 전자척의 자력특성에 관한 연구

맹희영,이용구 한국공작기계학회 2003 한국공작기계학회 춘계학술대회논문집 Vol.2003 No.-

The new square electro-magnetic chuck, which is using for the clamping devices on a grinding machine, is developed in this study to improve the convenience of grinding works. The various kinds of structures are recommended to find the most adequate magnetic characteristics through the analytical approach using finite element methods. The analyzed results are retrofitted to solve the drawbacks of previous models step by step by considering the magnetic fields, strength and distribution of drag force, and thermal deformations of chuck. such as high parallelism and flatness. Finally the best recommended models is designed to satisfy the KS specifications required for the commercial magnetic chuck. The prototype chuck with this dimensions and structures is manufactured. For this final model, the experimental verifications are investigated whether the KS specifications are satisfied.

반자성 물질에 의한 전자기차단효과에 관한 연구

황운택,Hwang, Yoon-Taek 한국정보통신학회 2008 한국정보통신학회논문지 Vol.12 No.8

비스무스는 융점이 낮아 취급이 용이하여 반자성체로서 전자기 차폐에 어떤 영향이 있는지 실험하기 쉽다. 그러나 실제 실험 재료를 원통으로 제작하여 측정된 경우를 찾아 볼 수 없다. 순수 비스무스는 반자성체로서 전자기 차폐에 어떤 영향이 있는가를 알기 위해서 비스무스를 다른 재료와 비교하기 위해서 원통으로 제조하였고 구리, 알루미늄, 철, 스텐레스 스틸도 원통을 만들어 정전차폐와 자기차폐를 저주파대에서 주파수 별로 측정하여 비교하였다. 그 결과 도표와 같이 구리와 비스무스 이중차폐가정전기에서는 제일 좋은 수치가 나왔다. 자기차폐에서는 철은 역시 가장 좋은 수치가 나왔고 비스무스는 별영향이 없이 나왔다. Bisumus has a low melting point, making it easier to handle. This allows us to test what type of effect diamagnetism has on electro static and magnetic field shields. However, the actual materials for experimentation have only ever been manufactured cylindrically, and so there have been no recorded cases of measurements to this effect. To understand what kind of effect pure bisumus as diamagnetism has on electro static and magnetic shields in comparison to other materials, bisumus, along with copper, aluminum and iron 스텐도, were used to make a cylinder each. These cylinders were then used to measure and compare the electro static shield and magnetic shield at different bands of frequencies, starting from a low frequency. As shown on the graph/chart/diagram, the best results were recorded for copper and bisumus as diamagnetism in an electro static field. In terms of magnetic shielding, iron provided the best results, as expected, whereas bisumus displayed minimal effect.

Phase-shifted and interleaved angle control for doubly Salient Electro-magnetic Machine

Weili Dai,Hao Tian,Jun Ding 제어로봇시스템학회 2014 제어로봇시스템학회 국제학술대회 논문집 Vol.2014 No.10

Doubly salient electro-magnetic machine using traditional control method has large torque ripple for dead-time during commutation process and its special structure. During commutation, electro-magnetic torque and power will decrease quickly due to all switches are off states. In order to avoid the problem, a novel phase-shifted and interleaved angel control strategy was proposed in this paper. The control algorithm can eliminate dead-time and shape phase current of electric machine to improve output power and reduce torque ripple by adjusting phase-shifted angle and interleaved angle. In this paper, the mathematical model of the machine and working principle of the control strategy were described in detail. Moreover, phase-shifted and interleaved angle optimum method based on low torque ripple and large output power was also given. Finally, a “field-circuit” co-simulation model of motor driving system based on novel control method was built by electro-magnetic finite element analysis and transient solver of control circuit, and simulation results verify theory analysis.

자기테이프용 Metal Powder의 초음파 분산에 의한 자기적 특성 향상에 관한 연구

김창곤,최현승,장학진,윤석영,김태옥,Kim, Chang-Gon,Choe, Hyeon-Seung,Jang, Hak-Jin,Yun, Seok-Yeong,Kim, Tae-Ok 한국재료학회 2001 한국재료학회지 Vol.11 No.11

It was investigated the effect of ultrasonic treatment on magnetic property of ultra fine magnetic Fe powders ($\alpha$-Fe) for magnetic tape. The properties were characterized with vibrating sample magnetometer (VSM), particle size analyzer (PSA) and scanning electron microscope (SEM). At 4hours ultrasonic treatment of 70 kHz, magnetic properties such as squareness ratio (S.Q. : 0.8868), orientation ratio (O.R. : 2.45) and switching field distribution (S.F. D. : 0.394) before taping were relatively enhanced. Cumulative particle size distribution of less than 5$\mu\textrm{m}$ fine powder was above 90% below 1 hour leaving time after ultrasonic treatment and it was supposed that ultrasonic treatment prevent aggregation. The magnetic values of S.Q. and S.F.D. of tape manufactured at 70 kHz and 4hour ultrasonic treatment were improved from 0.7747, 0.3818 to 0.8037, 0.3706, respectively. Electro-magnetic property used as in-output signal characteristic was improved, which showed that ultrasonic treatment developed the magnetic properties.

Biomimetic Swimming Mini-Robots Using Electro-Magnetic Actuation (EMA) System

Hyunchul Choi,Semi Jeong,Cheong Lee,Youngho Ko,Seong Young Ko,Jong-Oh Park,Sukho Park 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10

For the actuation of mini-robots, electromagnetic based actuation (EMA) methods were proposed. EMA system has many advantages for the wireless actuation of mini-robots. This paper introduces our proposed biomimetic swimming mini-robots such as tadpole robot and jellyfish robot. The biomimetic swimming mini-robots could be driven by an external alternating magnet field using three pairs of Helmholtz coils. The swimming mini-robots consist of a buoyant robot body, permanent magnets, and fins. Especially, the tadpole mini-robot has a single fin which is directly linked to the permanent magnet and the jellyfish mini-robot has multiple fins which have a permanent magnet at the end of fin. The external alternating magnetic field from three pairs of Helmholtz coils could generate the propulsion and steering force of the tadpole mini-robot and the jellyfish mini-robot in 2- and 3-dimensional (-D) space. Firstly, we demonstrated the fabrications of the EMA coil system and the mini-robots. Secondly, we summarized the locomotive algorithms of the mini-robots using EMA. Thirdly, we setup the control system for the EMA driven mini-robots, which consists of EMA coils, dual cameras, controller, power amplifier, and conventional joystick. Through various experiments, we evaluated the locomotion algorithms the swimming mini-robots using EMA system. Finally, we demonstrated the performances of the swimming mini-robots in 2-D and 3-D space.

전기수력학적 잉크젯 프린팅에서 기판과 자기장 세기의 영향

허종수(Jong Soo Heo),김건영(Keon Young Kim),이창열(Chang-Yull Lee) 한국항공우주학회 2017 한국항공우주학회 학술발표회 논문집 Vol.2017 No.11

Magneto-electro interaction of two offset indenters in frictionless contact with magnetoelectroelastic materials

Zhou, Y.T.,Pang, S.J.,Jang, Y.H. Butterworths [etc.] 2017 Applied mathematical modelling Vol.52 No.-

Within the theory of linear full-field magneto-electro-elasticity, magneto-electro interaction of two electrically-conducting and magnetically-conducting indenters acting over the surface of magnetoelectroelastic materials widely used in practical industries is examined. The operation theory, Fourier transform technique and integral equation technique are employed to address the two-dimensional, mixed boundary-value problem explicitly. The surface stresses, electric displacement and magnetic induction and their respective intensity factors are obtained in closed forms for two perfectly conducting semi-cylindrical indenters. Degradation from two perfectly conducting semi-cylindrical indenters to one single perfectly conducting cylindrical indenter is discussed. Numerical analyses are detailed to reveal the effects of the interactions between two semi-cylindrical indenters on contact behaviors subjected to multi-field loadings.

Magneto-electro-elastic vibration analysis of modified couple stress-based three-layered micro rectangular plates exposed to multi-physical fields considering the flexoelectricity effects

Mohammad Khorasani,Arameh Eyvazian,Mohammed Karbon,Abdelouahed Tounsi,Luca Lampani,Tamer A. Sebaey 국제구조공학회 2020 Smart Structures and Systems, An International Jou Vol.26 No.3

In this paper, based on the CPT, motion equations for a sandwich plate containing a core and two integrated face-sheets have derived. The structure rests on the Visco-Pasternak foundation, which includes normal and shear modules. The piezo-magnetic core is made of CoFe₂O₄ and also is subjected to 3D magnetic potential. Two face sheets at top and bottom of the core are under electrical fields. Also, in order to obtain more accuracy, the effect of flexoelectricity has took into account at face sheets' relations in this work. Flexoelectricity is a property of all insulators whereby they polarize when subject to an inhomogeneous deformation. This property plays a crucial role in small-scale rather than macro scale. Employing CPT, Hamilton's principle, flexoelectricity considerations, the governing equations are derived and then solved analytically. By present work a detailed numerical study is obtained based on Piezoelectricity, Flexoelectricity and modified couple stress theories to indicate the significant effect of length scale parameter, shear correction factor, aspect and thickness ratios and boundary conditions on natural frequency of sandwich plates. Also, the figures show that there is an excellent agreement between present study and previous researches. These finding can be used for automotive industries, aircrafts, marine vessels and building industries.

자기점성유체 댐퍼 코어의 최적화 설계를 위한 전자기장 해석

송준한(Song, June-Han),손성완(Son, Sung-Wan),전종균(Chun, C.K.),권영철(Kwon, Young-Chul),마양수(Ma, Y.S.) 한국산학기술학회 2008 한국산학기술학회논문지 Vol.9 No.6

외부에서 인가되는 전류의 세기에 따라 결합력의 세기가 달라지는 자기점성유체의 특성을 이용한 자기점성 유체 댐퍼는 유체의 결합력을 통해 전단력을 발생시켜 진통의 제어가 가능하다. 자기점성유체 댐퍼의 성능을 좌우 하는 코일 작동부의 최적화를 위해 유한요소해석을 이용해 코일 형상에 따른 전자기력의 성능비교를 실시하였다. 또한 고효율 댐퍼를 제작하기 위한 방법으로 다단의 코일 작동부를 가지는 댐퍼를 제안하였으며, 기존의 댐퍼와의 전자기적 성능 비교들 통해 댐퍼의 성능 비교를 수행하고 제한된 조건에서 최대의 효과를 가질 수 있는 방안을 제시하고 그에 따른 전자기장 해석을 수행하였다. The magneto-rheological fluid expresses different cohesiveness according to the strength of the external electric current. The magneto-rheological fluid damper, which uses such characteristics of the fluid, generates shear force due to the fluid’s cohesiveness. The core can be said to determine the magneto-rheological fluid damper’s performance. This study uses the finite element analysis to compare the performance of different electromagnetic forces, which are affected by the shapes of the coil, and thus to find the optimum design for the core. In addition, as a step to construct a high-efficient damper, we suggest a type of damper that can control multiple coils and compares the performance of this damper and that of the standard damper by comparing the performance of their electro-magnetic fields.