• Membrane and Water Treatment
• /
• 제10권5호
• /
• pp.361-372
• /
• 2019

Effect of different alkane based solvents on the stability of emulsion liquid membrane was investigated using normal alkanes (n-hexane, n-heptane, n-octane and n-decane) under various operating parameters of surfactant concentration, emulsification time, internal phase concentration, volume ratio of internal phase to organic phase, volume ratio of emulsion phase to external phase and stirring speed. Results of stability revealed that emulsion liquid membrane containing n-octane as solvent and span-80 (5 % (w/w)) as emulsifying agent presented the highest amount of emulsion stability (the lowest breakage) compared with other solvents; however, operating parameters (surfactant concentration (5% (w/w)), emulsification time (6 min), internal phase concentration (0.05 M), volume ratio of internal phase to organic phase (1/1), volume ratio of emulsion phase to external phase (1/5) and stirring speed (300 rpm)) were also influential on improving the stability (about 0.2% breakage) and on achieving the most stable emulsion. The membrane with the highest stability was employed to extract acridine orange with various concentrations (10, 20 and 40 ppm) from water. The emulsion liquid membrane prepared with n-octane as the best solvent almost removed 99.5% of acridine orange from water. Also, the prepared liquid membrane eliminated completely (100%) other cationic dyes (methylene blue, methyl violet and crystal violet) from water demonstrating the efficacy of prepared emulsion liquid membrane in treatment of dye polluted waters.

• 한국정밀공학회:학술대회논문집
• /
• 한국정밀공학회 2005년도 춘계학술대회 논문집
• /
• pp.280-283
• /
• 2005

This study performed by a previous research for the applying expert system to active vibration control algorithm. In order to increase productivity and efficiency, high-speed rotating machines become popular these days. They are likely to vibrate and cause machine failure even though they have small unbalance. Therefore, a high-speed rotating machine needs a balancing technique. ISO 11342 classifies flexible rotors in accordance with their balancing requirements and establishes methods of assessment of residual unbalance. But, even if they finished balancing work, they have harmful effect vibration under the high-speed rotating environment. This vibration effect is very small, but it must be removed for the improvement of the rotor's spin accuracy. This paper introduces a new active control method that remove the exciting force by a phase control. For this method, the high-speed rotating rotor was reconstructed by a flexible rotor model. The forces which excite the rotating system suppose cyclic forces, we obtain the responses by numerical method. And then through the pattern analysis about the vibraton responses, the controler generate the control force with the reverse phase and similar magnitude. This paper suggest an phase control method and shows how to improve the rotating vibration accuracy of the flexible rotor dynamics system using phase control method.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
• /
• 제2B권3호
• /
• pp.115-124
• /
• 2002

This paper presents an active auxiliary edge-resonant DC link snubber with a ringing surge damper and a three-phase voltage source type zero voltage soft-switching inverter with the resonat snubber treated here for the AC servo motor driver applications. The operation of the active auxiliary edge-resonant DC link snubber circuit with PWM voltage is described, together with the practical design method to select its circuit parameters. The three-phase voltage source type soft-switching inverter with a single edge-resonant DC link snubber treated here is evaluated and discussed for the small-scale permanent magnet (PM) type-AC servo motor driver from an experimental point of view. In addition to these, the AC motor stator current and its motor speed response for the proposed three-phase soft-switching inverter employing Intelligent Power Module(IPM) based on IGBTS are compared with those of the conventional three-phase hard-switching inverter using IPM. The practical effectiveness of the three-phase soft-switching inverter-fed permanent magnet type AC motor speed tracking servo driver is proven on the basis of the common mode current in a novel type three-phase soft-switching inverter-fed AC motor side and the conductive noise on the mains terminal interface voltage as compared with those of the conventional three-phase hard-switching inverter-fed permanent magnet type AC servo motor driver for the speed tracking applications.

• 한국철도학회논문집
• /
• 제20권5호
• /
• pp.588-594
• /
• 2017

영구자석 저감형 동기전동기는 기존의 고속철도 추진용 유도기보다 높은 효율과 출력밀도를 보이고, 일반적인 영구자석 동기전동기에 비해 자석 사용량을 줄여 가격을 낮출 수 있다. 또한 5상 구동 시스템을 사용할 경우 3상 시스템에 비해 낮은 토크리플과 높은 출력밀도를 가지게 된다. 이러한 특성으로 인해 5상 영구자석 저감형 동기전동기는 고속철도 추진용 전동기로 적합한 특성을 가진다. 본 연구에서는 집중상수모델과 유전알고리즘을 이용하여 3상 및 5상 영구자석 저감형 동기전동기 3kw 축소모델을 최적설계하고 이들의 특성을 비교하였다. 또한 유한요소해석을 이용하여 최종 보정설계를 진행한 3상 및 5상 전동기를 제작하고 실험을 통해 해석값을 검증하였다.

• International Journal of Fluid Machinery and Systems
• /
• 제3권3호
• /
• pp.211-220
• /
• 2010

The objective of this study is to clarify the occurrence of the high-speed mode of unsteady swirling flows in straight tubes. The unsteady flows generated in the tube were measured by means of a semiconductor-type pressure transducer and an FFT analyzer. The high-speed mode measured has rotational speed which is approximately equal to or higher than the peripheral velocity of the swirling flow. The unsteady flow is due to cell rotation in the circumferential direction of the tube. The occurrence of the high-speed mode was confirmed, and the characteristics (rotational speed, pressure amplitude, and phase) of this mode were clarified. In order to understand the measured unsteady flows, the three dimensional vortex core profiles were discussed based on the distributions of the pressure amplitude and phase.

• 대한전기학회:학술대회논문집
• /
• 대한전기학회 2011년도 제42회 하계학술대회
• /
• pp.983-984
• /
• 2011

An effective estimation method of equivalent circuit parameters of three-phase induction motor by using FEM is presented in this paper. Arbitrary three torque-speed points at asynchronous speed on the torque-speed curve are required by using time-stepping FEM, then the equivalent circuit parameters of IM can be calculated rapidly with presented method. After obtaining the equivalent circuit parameters, the general analysis method based on equivalent circuit can be used to get entire torque-speed curve very quickly. Although the purely numerical method such as FEM also can estimate torque-speed curve directly and accurately, however, usually this process is time consuming.

• 전기학회논문지
• /
• 제58권7호
• /
• pp.1313-1320
• /
• 2009

This paper analyzes the steady-state operating characteristics of doubly-fed induction generator(DFIG) and fixed-speed induction generator(FSIG) in wind turbine system. It also presents a modeling and simulation of a grid-connected wind turbine generation system for dynamics analysis on MATLAB/Simulink, and compares the responses between DFIG and FSIG wind turbine systems with respect to wind speed variation, 3-phase fault and 1-phase ground fault of the network. Simulation results show the variations of generator's active/reactive output, rotor speed, terminal voltage, fault current, etc. Case studies demonstrate that DFIG illustrates better performance compared to FSIG.

• Journal of Power Electronics
• /
• 제1권1호
• /
• pp.19-25
• /
• 2001

A high speed, three phase, 12/8 pole, 225 kW switched reluctance motor (SRM) has been designed and analyzed. A circuital approach has been used to find the geometry, windings parameters and electromagnetic loading. Then, the 3D finite element method (FEM) has been used to calculate the static torque more accurately and optimize the design. The efficiency of the designed SRM is almost constant over wide range of speed and its phase current is less sensitive to the speed than that of an induction motor of the same rating. Recommendations for manufacturers and users are given.

• 한국분말재료학회지
• /
• 제8권1호
• /
• pp.42-49
• /
• 2001

Ti-50Ni(at%) and Ti-40Ni-10Cu(at%) alloy powders have been fabricated by ball milling method, and their microstructure and phase transformation behavior were investigated by means of scanning electron microscopy/energy dispersive spectrometry, differential scanning calorimetry (DSC), X-ray diffractions and transmission electron microscopy. In order to investigate the effect of ball milling conditions on transformation behavior, ball milling speed and time were varied. Ti-50Ni alloy powders fabricated with the milling speed more than 250 rpm were amorphous, while those done with the milling speed of 100rpm were crystalline. In contrast to Ti-50Ni alloy powders, Ti-40Ni-10Cu alloy powders were crystalline, irrespective of ball milling conditions. DSC peaks corresponding to martensitic transformation were almost discernable in alloy powders fabricated with the milling speed more than 250 rpm, while those were seen clearly in alloy powders fabricated with the milling speed of 100 rpm. This was attributed to the fact that a strain energy introduced during ball milling suppressed martensitic transformation.

• 전력전자학회논문지
• /
• 제12권4호
• /
• pp.310-317
• /
• 2007

본 논문에서는 평형 2상유도전동기에 대한 시스템 방정식을 유도하고 해석하였으며, 동기좌표계에서 평형 2상유도전동기의 속도제어 특성을 분석하였다. 3상 교류 전동기의 속도제어에 범용적으로 적용하는 벡터제어이론을 "2상 인버터 구동 2상 유도전동기 시스템"에 수정하여 적용하였으며, 이 때 2상 유도전동기 시스템은 수정된 간접 벡터제어이론에 의해 속도 제어하였다. 2상 유도기의 벡터제어의 특성과 근사함을 보여주기 위해 제안 시스템을 시뮬레이션하였다. 최종적으로 실험을 통해서 제안 시스템이 벡터제어에 확실히 적응하는 것을 확인하였다.