• 한국철도학회:학술대회논문집
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• 한국철도학회 2009년도 춘계학술대회 논문집
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• pp.1649-1654
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• 2009

Induction motors widely use in industry because structure is simple and hard and cost is generally cheap and they are easy to control. In recently, because of saving steel, ventilation and benefit of frame fixing, rectangular core type induction motors use in industry more and more. This paper presents current characteristic according to stator core cutting degree in three-phase induction motor (IM) with rectangular stator core. According to stator cutting degree, magnetic saturation and paths of flux are changed. Because of these situations, phase currents are unbalance and are produced harmonic components and they cause decrease of efficiency. We analyze each $10^{\circ}$ from $0^{\circ}$ to $30^{\circ}$ using 2-D finite element analysis (FEA). Optimal stator cutting core degree selection supplies stable currents and efficiency improvement. In this paper, loss separation test was executed by IEEE Std. 112-98 Method B and we compare with the result of loss separation by Simulation using FEM and by Experiment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.27-29
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• 1999

The starting characteristics of induction motors strongly depend on the leakage reactance and resistance of stator winding and rotor circuits. The magnetic field saturation in the rotor bridge of closed slot rotor makes it very difficult to compute the leakage reactance of rotor bars. This paper describes a comparison between timestep finite element analysis, time-harmonic analysis and experimental results for a test model which can represent the nonlinear behaviour of the rotor bridge.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 하계학술대회 논문집 A
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• pp.315-317
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• 1999

This paper presents a method for determining of the equivalent d-q model parameters of three-phase squirrel cage induction motors. The method is based on the use of a finite-element field calculation which enables the precise slot geometry to be modelled accurately, and includes the effects of magnetic saturation of iron core. The proposed method can reduce computational costs compared with the method that needs the iterative field analysis to obtain the impedance. It is verified that the circuit inductances are shown as functions of the current.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2002년도 추계학술대회 논문집
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• pp.21-24
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• 2002

The vector control system of an induction motor is the high performance drive system to achieve the instantaneous torque control. The vector control system is greatly divided into the direct control, and the indirect control that the most widely is used, The indirect vector control needs the rotor time constant, which changes widely according to the temperature, frequency, and current amplitude. The incorrect time constant leads to the saturation of magnetic flux or under-excitation phenomena. As a result, that deteriorate the control performance. Therefore, in this paper, the effect of time constant variation is investigated and its on-line tuning algorithm is proposed. The time constant using the torque angles was calculated and that of the validity of algorithm proposed was proved through the computer simulation and the experiment.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.884-885
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• 2007

This paper presents an window based user-friendly designed characteristics analysis program of permanent-split capacitor single-phase induction motor. For the analysis, equivalent magnetic circuit and symmetrical coordinate method are used. The saturation effect and iron loss of stator and rotor core are considered. The analysis program is made to GUI type which can be used easily by many elementary designer. The accuracy of analysis is verified by comparison with experimental results.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 C
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• pp.1066-1068
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• 1999

Magnetic field is commonly used in low temperature processing plasmas in order to obtain high density. E $\times$ B magnetron or surface multipole configuration were most popular. However, the properties of capacitively coupled rf plasma confined by axially applied static magnetic fields have rarely been studied. In this paper, the effects of magnetic field on the characteristics of 13.56MHz/40KHz argon plasma will be reported. Ion saturation current, electron temperature and plasma potential were measured by Langmuir probe and omissive probe. At low pressure region ($\sim$10mTorr), ion current was increased by a factor of 3 - 4 due to reduction of diffusion loss of charged particles to the wall. It was observed that magnetic field induces large time variation of the plasma potential. The experimental result was compared with particle-in-cell simulation. It was also observed that electron temperature tend to decrease with increasing magnetic induction level for 40KHz discharge.

• 한국자기학회지
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• 제3권2호
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• pp.135-138
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• 1993

Fe-B계 비정질합금에 Al을 치환한 $Fe_{82}B_{18-x}Al_{x}$ 및 $Fe_{80}B_{20-x}Al_{x}$급속응고합금의 포화자왜 인장응력에 의한 자기탄성효과가 조사되었다. 포화자왜는 Al 치환량이 증가 할수록 증가 하며, 비정질 $Fe_{82}B_{14}Al_{14}$합금에서 45 ppm으로 가장 높다. 비정질 $Fe_{82}B_{14}Al_{14}$ 합금의 인장응력에 따른 최대자속밀도의 변화율은 약 $0.026\;T.mm^{2}/N$으로 고분해능 역학센서로 응용이 가능할 것으로 예상된다.

• 한국전기전자재료학회논문지
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• 제23권12호
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• pp.988-995
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• 2010

In this study the (Alnico, Sm-Co) bonded magnets were fabricated by mixing the Sm-Co added alnico alloy powders with epoxy resin and binder, appropriately. Also, the hybrid ring magnets of (Alnico, Sm-Co)/Sr-ferrite were fabricated by coupling the Sr-ferrite composite layer with an (Alnico, Sm-Co) magnet. The magnetic properties of (Alnico, Sm-Co) ring magnets were varied with the amount of Sm-Co powders. The addition of Sm-Co powders increased a remanent induction($B_r$) and coercive force($_BH_C$), while decreasing a surface flux density and repulsive distance. The surface flux density and repulsive distance for the (Alnico, Sm-Co) ring magnet increased with a magnetizing voltage up to about 160 V and reached an apparent saturation point. Also, the measurements of temperature and moisture characteristics showed that the surface flux densities of N-S poles and repulsive distance decreased a little within 4% after 10 days passed.

• 한국재료학회지
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• 제12권8호
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• pp.600-607
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• 2002

The Ni-Zn synthetic ferrite were acquired from thermally decomposing the metal nitrates Fe(NO$_3$)$_3$.$9H_2$O, Zn($NO_3$)$_2$.$6H_2$O, Ni($NO_3$)$_2$. $6H_2$O, and Cu($NO_3$)$_2$. $3H_2$O at $150^{\circ}C$ for 24 hours and was calcined at $500^{\circ}C$. Each of those was pulverized for 3, 6, 9, and 12 hours in a steel ball mill and was sintered between $700^{\circ}C$ and $1,000^{\circ}C$ for 1 hour, and then their microstructures and electromagnetic properties were examined. We could make the initial specimens chemically bonded in liquid at the temperature as low as $150^{\circ}C$, by using the melting points less than $200^{\circ}C$ of the metal nitrates instead of the mechanical ball milling, then narrowed a distance between the particles into a molecular level, and thus lowed sintering temperature by at least $200^{\circ}C$ to$ 300^{\circ}C$. Their initial permeability was 50 to 400 and their saturation magnetic induction density and coercive force 2,400 G and 0.3 Oe to 0.5 Oe each, which were similar to those of Ni- Zn ferrite synthesized in the conventional process. In the graph of initial permeability vs frequencies, we could observe a $180^{\circ}C$rotation of the magnetic domain, which appears in a broad band of microwave near the resonance frequency.

• 한국재료학회지
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• 제5권8호
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• pp.1040-1044
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• 1995

Sm의 농도가 각각 0.3, 0.4, 0.6인 세종류인(YSmLuCa)$_3$(FeGe)$_{5}$ $O_{12}$ 가넷트 박막을 LPE법으로 비자성재료인 Gd$_3$Ga$_{5}$ $O_{12}$(GGG)기판상에 성장시켜, 버블 자성재료의 자기적 성질을 조사하였다. 공명폭 ΔH는 4$\pi$Ms의 증가에 따라 증가하였고 Sm 농도의 감소에 따라 감소한다. 수직 자기 이방성에너지 Ku는 Sm증가에 따라 증가하며 같은 Sm농도에서는 4$\pi$Ms의 증가에 따라 증가한다. 자벽 이동도는 4$\pi$Ms의 증가에 따라 증가하며 Sm의 증가에 따라 감소한다. Ms.ΔH의 곱이 일정한 사실로 부터 새로운 자기손실인자 Eι을 구할 수 있으며 이는 Sm의 농도에 의존한다.ι을 구할 수 있으며 이는 Sm의 농도에 의존한다.