• 한국초전도학회:학술대회논문집
• /
• v.12
• /
• pp.33-33
• /
• 2002

• Journal of IKEEE
• /
• v.26 no.4
• /
• pp.653-658
• /
• 2022

This paper presents a Maximum Torque per Ampere (MTPA) control algorithm for an interior permanent magnet synchronous motor (IPMSM) drive considering the permanent magnet (PM) flux linkage variations due to PM temperature variation. PM flux linkage are estimated in real time via a Gopinath style stator flux linkage observer and a torque error correction factor is calculated from the estimated PM flux linkage. A 2-dimensional (2D) MTPA look-up table (LUT) is developed to achieve the MTPA trajectory reflecting PM flux linkage variation for compensating torque error occurred by parameter variation. The proposed IPMSM control algorithm is verified through simulations.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2001.07a
• /
• pp.66-69
• /
• 2001

Effect of $N_2$ flow rate on properties of GaN thin films grown by plasma-enhanced molecular beam epitaxy(PEMBE) was discussed to optimize the quality of thin films. It was found that at low $N_2$ flow rate indicating high III/V flux ratio, the growth rate of GaN thin films was controlled by $N_2$ flux, and at high $N_2$ flow rate the growth rate was not controlled by $N_2$ flux any longer. It was also found that III/V flux ratio affected film quality. The film grown at higher $N_2$ flow rate showed low background carrier concentration, higher carrier mobility, and narrow FWHM in band-edge emission of low temperature PL. It is thought that the film in more Ga flux region was grown by 2-dimensional layer-by-layer growth mode, and the film in more nitrogen region was grown by 3-D island growth mode. All samples exhibited a good crystallinity.

• Proceedings of the KIEE Conference
• /
• 2002.07d
• /
• pp.2067-2069
• /
• 2002

The study of the vector control of the induction machine without speed sensor is going on and there are the adaptive performance method to use the flux observer. This study is to make the vector control without the speed sensor based on the flux oriented reference vector control theory. This paper proposes the new speed follow-up method to deduce the current value in the current sensor and the 2 order flux observer based on the observer theory and examine the possibility to realize the flux oriented vector control system using the simulation in this proposed method of this study.

• Journal of Advanced Marine Engineering and Technology
• /
• v.24 no.5
• /
• pp.25-32
• /
• 2000

In this paper, experiments investigating the high-temperature region heat transfer coefficients for the spray cooling of hot flat plates were performed by down spray water using flat spray nozzles. The heat transfer surface is made of copper and is 100mm in length and 40mm in width and 15mm in thickness. The experimental condition of spray are as follows: temperatures of the water droplets are T=20~$80^{\circ}C$ and droplets volume fluxes are D=0.001565~0.010438$m^3/m^2s$. Next, correlating equations for the heat transfer characteristics of spray cooling in the high temperature region are developed from the effects of droplets volume flux and the surface temperature of heat transfer plate.

• Journal of Electrical Engineering and Technology
• /
• v.9 no.4
• /
• pp.1290-1295
• /
• 2014

In this paper, various configurations of octagonal wound transformer core topology, which has previously proved advantages on conventional wound cores, are studied. Each configuration has different joint types and different placement of joint zones on the core. Magnetic flux distributions and power losses of each configuration are analyzed and compared. Comparisons are based on both 2D&3D finite element simulations and experimental studies. The results show that, joint types and their placements on the core cause local flux accumulations and dramatically affect power loss of the core.

• Journal of Magnetics
• /
• v.15 no.2
• /
• pp.64-69
• /
• 2010

This paper describes the development of a novel transverse flux linear motor (TFLM) excited by permanent magnets (PMs). It combines the advantage of two different TFLMs and produces high thrust with reduced normal force. The magnetic field is analyzed by combining the three-dimensional (3D) equivalent magnetic circuit network (EMCN) method with 2D finite element analysis. The experimental findings of the prototype motors are in good agreements with the analysis results, and demonstrate the potential of the proposed motor as a direct drive requiring relatively long displacement of a mover.

• Journal of Korean Society of Water and Wastewater
• /
• v.18 no.6
• /
• pp.770-777
• /
• 2004

Three pilot-scale membrane systems were operated using lake water as influent in this study. Microfiltration (MF) membrane with pore size of 0.01 m was used in Systen I of which filtration mode was set at constant pressure of $1kgf/cm^2$. Ultrafiltration (UF) membranes with molecular cutoff (MWCO) of 80,000 and 13,000 were used in System II-1 and II-2, respectively. Constant flow mode was applied at the range between 0.7 and $1.5m^3/m^2{\cdot}d$ (average of $1.1m^3/m^2${\cdot}d) for System II-1 and between 0.37 and $1.65m^3/m^2{\cdot}d$ (average of $1.18m^3/m^2{\cdot}d$) for System II-2. In System I, the flux changed from $1m^3/m^2{\cdot}d$ to $0.2m^3/m^2{\cdot}d$ during the operation time of 5 months. System II showed recovery of 94% under the allowable maximum pressure of $3kgf/cm^2$ during the same operation period. From these results, the efficient operation was observed in constant flow mode with respect to filtration time and recovery. Average filtrate turbidity showed 0.0071 NTU in System I and 0.0054 NTU in System II, which implied that high turbidity removal was obtained in both MF and UF systems with no significant difference between MF and UF. From the fact that membrane flux depends largely on membrane type and operation mode, a guideline of optimum design and operation should be suggested for application of membrane systems to full scale water treatment.

• Journal of Magnetics
• /
• v.8 no.4
• /
• pp.160-163
• /
• 2003

In magnetic flux measurement, output voltage drift of electronic integrator is an essential problem. In this work, we have developed a new kind of Miller type integrator using a sample and hold amplifier. Input bias current was measured and this value was hold in the sample and hold amplifier, after that input bias current of Miller integrator was compensated automatically using the value which holds in the sample and hold amplifier. Developed flux-meter shows the drift of flux-meter are smaller than 10$^{-5}$ Wb/min in full scale of 10$^{-2}$, and we could also measure multi-channel magnetic flux simultaneously.

• Membrane and Water Treatment
• /
• v.10 no.2
• /
• pp.127-137
• /
• 2019

The D2EHPA/TBP co-extractants immobilized PolyHIPE membrane can be used for the selective separation of Mn (II) from Co (II). By solvent-nonsolvent method, D2EHPA/TBP co-extractants can be effectively immobilized into PolyHIPE membrane. The pore structure of PolyHIPE membrane and the presence of TBP enhance the stability of immobilized co-extractants. The optimal operating conditions for the separation of Mn (II) and Co (II) are feeding phase at pH 5.5, sulfuric acid concentration in the stripping phase of about 50 g/L and stirring speed at 400 rpm. The D2EHPA/TBP co-extractants ratio of 5:1 shows synergetic effect on Mn/Co separation factor about 22.74. The removal rate and recovery rate of Mn (II) is about 98.4 and 97.1%, respectively, while for Co (II) the transport efficiency is insignificant. The kinetic study of Mn (II) transport shows that high initial flux, $J_f^o=80.1({\mu}mol/m^2s)$, and maxima stripping flux, $J_s^{max}=20.8({\mu}mol/m^2s)$, can be achieved with D2EHPA/TBP co-extractants immobilized PolyHIPE membrane. The stability and reusability study shows that the membrane can maintain a long term performance with high efficiency. High purity of Co (II) and Mn (II) can be recovered from the feeding phase and stripping phase, respectively.