• 대한전기학회:학술대회논문집
• /
• 대한전기학회 1999년도 하계학술대회 논문집 A
• /
• pp.15-17
• /
• 1999

A voice-coil-type LOA consists of the NdFeB permanent magnets with high specific energy as the stator, a coil-wrapped nonmagnetic hollow rectangular structure. We have to obtain the back-EMF constant ${\kappa}_E$ from 3D FEA and experiments, precisely. The ${\kappa}_E$ and other parameters provide the transfer function, through which is derived the frequency response characteristics. Inverter-fed LOA is examined aiming to compare with results of simulation.

• 태양에너지
• /
• 제20권4호
• /
• pp.61-67
• /
• 2000

The purpose of this study is to improve heat transfer by attaching rectangular fins to tube. Experiments were carried out under the following conditions - Aspect ratio$(W_f/R_f)$ is 0.7, 1.2 and 1.8. Temperature conversion between high and low positions of water in the thermal storage appeared because maximum density point of water is about $4^{\circ}C$ and inlet direction of working fluid influenced conductive heat transfer Compared with the unfinned tube(bare tube), the rectangular tube increased the ice thermal storage energy and the ice thermal storage energy was increased as aspect ratio was increased.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제48권1호
• /
• pp.19-26
• /
• 1999

A moving-coil-type linear motor, designed and fabricated, is consisted of the NdFeB permanent magnets with high specific energy as the stator, a coil-wrapped nonmagnetic hollow rectangular structure and an iron core as a pathway for magnetic flux. The interaction between permanent magmet and armature fie1d, so called "push/pull effect", is to shift the airgap flux density variation due to the magnet alone by a certain amount. Thrust therefore is shift downward or upward. The push/pull effect was presented through the FEM analysis and the static tests. We compared the thrust obtained through the FEM analysis with the static tests. Finally, we present the linearity and correction coefficients of the thrust in consideration of the push/pull effects.l effects.

• 한국자기학회지
• /
• 제14권6호
• /
• pp.232-235
• /
• 2004

아날로그 형태의 신호를 전송하기에 적합한 특성을 보이는 선형 GMR(giant magnetoresistance) 아이솔레이터를 모델링하여 입력전류에 따른 출력전압과 전류를 조사하였다. GMR 아이솔레이터를 자기적 부분과 전기적 부분으로 나누고 선택된 스핀밸브 소자의 MR(magnetoresistance) 결과를 대입하여 출력전압을 구할 수 있는 순서도를 설정하였다. 자기적 모델링으로는 평판 코일의 3차원 모델을 FEM방법으로 해석하여 입력전류에 의해 생성되는 자장의 세기를 구하였으며, 여기에서 자기코어층이 있는 경우 50% 이상 더 커지는 결과를 얻었다. 그리고 아이솔레이터의 출력전압파형을 계산한 결과 입력 코일 전류에 따른 궤환 코일 전류가 $I_{out}$ = $I_{in}$ -5 mA의 선형함수와 비교시 평균 $\pm$0.25 mA 이내의 차이로 근사한 값으로 계산되었다. 또한 입력되는 코일 전류가 구형파일 때, 출력전압의 반응시간과 파형을 계산하였으며, 이때 최저전압에서 최대 전압까지 상승 및 하강하는 시간은 연산증폭 기의 slew rate가 0.3 V/${\mu}\textrm{s}$ 일 때, 최저전압에서 최대 전압까지 상승 및 하강하는 시간은 6 ${\mu}\textrm{s}$였다.

• 전기학회논문지
• /
• 제63권3호
• /
• pp.404-408
• /
• 2014

In this research we evaluate the excitation homogeneity and SAR of three different Tx arrays after B1+ Shimming in the human body at 3T. Through the simulations, we compared the field properties that are standard deviation and mean value of transverse magnetization for 1) strip line TEM array, 2) rectangular loop array, 3) combined array of strip line element and rectangular loop and shown the utilities of B1+ shimming in human body model. After B1+ shimming, it is evaluated four different types of SAR for body mesh through whole body simulation; those are average, maximum 1-cell, maximum 1-gram, and maximum 10-gram SAR. It appears that in this particular comparison an array based on strip line elements can produce better homogeneity and lower SAR than an array of rectangular loops or an array of combined elements (strip line and loop). While many factors are considered in designing coils for production, it is hoped that methods and results like these will be used in the future to guide decisions and maximize benefit.

• 대한기계학회논문집A
• /
• 제35권12호
• /
• pp.1573-1578
• /
• 2011

이 논문에서는 전자기구동시스템을 기반으로 이동 및 드릴링 기능을 수행하는 의료용 마이크로로봇 시스템을 제작하고 평가하였다. 마이크로로봇은 너무 작아 내부에 배터리나 제어장치를 삽입 할수 없다. 이 결점을 극복하기 위하여 외부에서 전자기 코일 시스템을 이용하여 전자기장의 힘으로 마이크로로봇을 구동 시킨다. 전자기 구동 코일 시스템은 x, y, z 각축에 사각형 타입의 헬름홀쯔 코일 3 쌍과 z축에 솔레노이드형 맥스웰 코일 1 쌍이 배치 되어 있고, 각 코일에 인가되는 전류값의 조절에 따라 구동에 필요한 자기장을 발생 시킨다. 다양한 실험을 통하여 우리는 제안된 시스템을 이용하여 마이크로로봇이 3 차원 공간에서 이동 가능하며 드릴링 기능을 수행할 수 있다는 것을 보였다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
• /
• 제48권5호
• /
• pp.241-248
• /
• 1999

Recently, many linear motion generators and motors are rapidly finding applications that ranges from short stroke linear motion vibrators, such as dynamic cone type loudspeakers to stirling engine driven linear reciprocating alternators, compressors, textile machines etc. The stroke-length may go up to 2m, and the maximum speed is in the range of 5 to 10m/s with oscillating frequency as high as 15 kHz. Therefore, the linear oscillating actuators(LOAs) may be considered as variable speed drivers of precise controller with stoke-length and reversal periods during the reciprocating motion. In this paper, the design, fabrication, experiments, and extraction of control parameters of a moving coil type LOA for driving of linear reciprocating motion control systems, are treated. The actuator consists of the NdFeB permanent magnets with high specific energy as the stator produced magnetic field, a coil-wrapped nonmagnetic hollow rectangular bobbin structure, and an iron core as a pathway for magnetic flux. Actually, the design is accomplished by using FEM analysis for the basic configuration of a magnetic circuit, and characteristic equations for coil design. In order to apply as the drivers of a linear motion reciprocating control system, the control parameters and circuit parameters, such as input voltage-stoke, exciting frequency-stoke, coil inductance and so on, are extracted from the analysis and experiments on concerning a fabricating LOA.

• 전기학회논문지
• /
• 제57권6호
• /
• pp.1026-1031
• /
• 2008

We report on the design and experimental results of a large diameter faraday rotator for the high-power laser system(KLF: Kaeri laser facility) that was completed in late 2007s at Korea Atomic Energy Research Institute. The design involves modelling the magnetic field of cylindrical coil with large diameter(110 mm). Magnetic field generation coil is designed by 6 layers using a rectangular wire with cross-sectional area $3{\times}5[mm^2]$. We obtain an isolation ratio for optical feedback of 35 dB at 1064 nm and magnetic field strengths ${\sim}25kG$. We expect that the design can be widely used optical isolators in high-power laser system.

• 비파괴검사학회지
• /
• 제28권6호
• /
• pp.496-503
• /
• 2008

We propose rectangular type spiral coils with folded comers for the applications to low frequency guided wave magnetostrictive transducers and describe a method for making the proposed coils from insulated electrical wire such as enameled copper wire. Expressions for the electrical properties of the coils are also presented and compared with experimental measurements. An overlapped-2-channel folded-comer spiral-coil array is fabricated and applied to a magnetostrictive strip transducer generating and detecting fundamental torsional mode guided waves. From the results we conclude that the design and fabrication method make it possible to use the magnetostrictive transducers optimized for various guided wave applications and also will greatly help engineers gain easy access to the optimized transducers.

• 조명전기설비학회논문지
• /
• 제25권7호
• /
• pp.78-82
• /
• 2011

In this paper, magnetic field compensation system with an open architecture and can be installed indoors is designed and measured by fabricated. To verify the shielding effectiveness, two rectangular helmholtz coils with 3-axis are fabricated to generate magnetic field and measured magnetic field inside compensation coil for 1~60[Hz], According to measurements, AC shielding effectiveness of compensation system is 96[%] of 1[Hz], 95[%] of 30[Hz] and 90[%] of 60[Hz]. The performance of system therefore can be used as the magnetically shielded room for medical and industrial field.