• Journal of the Korean Society for Precision Engineering
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• v.18 no.4
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• pp.209-218
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• 2001

Ultrasonic motors are newly developed motors which are expected to be useful as actuators in many practical systems such as robot arms or manipulators because of several advantages against the electromagnetic motors. However, the precise control of the ultrasonic motor is generally difficult due to the absence of appropriate and rigorous mathematical model. Furthermore, owing to heavy nonlinearity, the position control of a pendulum system driven by the ultrasonic motor has a problem that control method using multiple neural network controllers based on a fuzzy inference system that can determine the initial position of the pendulum in the beginning of control operation. In addition, and appropriate neural network controller that has been learned to operate well at the corresponding initial position is adopted by switching schemes. The effectiveness of the proposed method was verified and evaluated from real experiments.

• Transactions of the Korean Society of Automotive Engineers
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• v.25 no.3
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• pp.344-349
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• 2017

Suspension noise from under a passenger car is one of the important factors that impact the perceptual quality for drivers. However, it is difficult to validate this by component level testing in the early stage of development, because suspension noise caused by interaction of the related parts has been found at saleable vehicles late during development or at the manufacturing stage, when many customers have already filed for claims. This study proposed a validation testing under research by the DFSS process that enables reproduction of vehicle level noise by component level testing using a shock absorber with the related parts, such as urethane bumper and top mount. This study also developed a compromised test matrix while analyzing the noise factors through experimental design and analysis of variance to determine what factors can affect noise. Based on this study, we expect that the vehicle level and customer claim can be validated during initial development timing by a more reliable component noise validation test.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.60 no.2
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• pp.91-93
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• 2011

This paper is presented for the performance of the Fluid Dynamic Bearing(FDB) by the groove design and the tooling condition. Recently, spindle motors which require smaller size, lower sound noise, lower vibration, and higher speed of the rotation have been placed in high value-added products including Digital Lightening Processors(DLP), Hard Disk Drives(HDD), and ODDs. The spindle motors using the sintered porous metal bearing have higher vibration and acoustic noise by dry contact and large tolerance of the bearing parts. The Fluid Dynamic Bearing (FDB) with grooves is appropriate for spindle motors adequate in regards to mechanical vibration and acoustic noise. The paper shows the performance comparisons of between sintered porous metal bearing and FDB, and each FDBs according to the tooling deviations of grooves by the Finite Element Analysis(FEA) of the mechanical field. This paper shows the methods to make the grooves, the groove's depth, and the prototype of the motor with the fluid dynamic bearing. The performance characteristics of the grooves with the FDB are verified by the experimental results.

• Journal of Electrical Engineering and Technology
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• v.10 no.5
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• pp.2170-2178
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• 2015

This paper presents the effective and reliable speed control of PMDC motors under variable loads and reference speeds. As is known DC motors are more preferred in industrial practices. This is that, the PMDC motors don’t require brush and commutator care and to increase in torque per motor depending on developments in power electronics. In this study, proportional-integral controller (PI) and fuzzy logic controller (FL) have been designed for speed control of PMDC motor. In the design of these controllers, characteristics such as minimum overrun time, response time to the load, settling time and ideal rise time have been taken into consideration for better stability performance. In this design, the best system response was searched by examining the effect of different defuzzification methods onto the fuzzy logic system response. In conclusion, it has been seen that FL controller has a better performance for variable speed-load control of PMDC motor compared to PI controller.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.1928-1934
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• 2014

Induction motors are widely used due to their rugged, robust and easy to care features. Since they are heavily used in industry, testing of three phase induction motors have play a vital role. In order to determine motor equivalent circuit parameters, efficiency of motor, squirrel caged laboratory sized an induction motor test setup is prepared. It is suitable for the induction motor with the frame size of 100 and 112. A virtual Instrumentation typed engineering workbench (called as LabVIEW) software packet, is utilized as a graphical user interface program. Motor input power is measured by measuring the input voltage, current and power factor with the help of hall effect typed voltage and current transformers. Also, the output power is measured by measuring the speed and torque with the help of an encoder and torque sensor. All outputs of the voltage and current transformer, encoder and temperature, torque sensors are given to the Data Acquisition Card (DAQ) which acquires the data for processing and then the equivalent circuit parameters, efficiency, performance and loading characteristics are found out, using LabVIEW based user interface. It is suggested to use this test rig for the quality control of produced motors in industry, and an educational experiment setup in the school laboratories.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.460-463
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• 2011

Different kinds of solid rocket motors manufactured for various aim have their own shelf life. So they must be done away if not used. In general, ammonium perchlorate(AP) has used in the process of solid rocket motors, which is environmental pollutant. Out-burning and out-detonation were usual in the past, but they polluted the surrounding environment and raised safety issues. As an alternative to resolve these, water-washout process to separate the propellant from rocket motors and an eco-friendly way for recovering AP are studied in this paper.

• The Journal of Industrial Distribution & Business
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• v.9 no.9
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• pp.45-52
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• 2018

Purpose - This case study is dedicated to the study of the presence of KIA Motors in the Kingdom of Saudi Arabia (KSA) and its market and entry strategies for strategic globalization that allowed the company to establish itself within a conservative and clustered marketplace dominated by American and Japanese international brands. Research Design, data, and methodology - The main information for the case was gathered through an interview and questionnaire from the executives of the KIA Al Jabr, which got the exclusive dealership in Saudi Arabia. Moreover, secondary data were obtained from reliable and authoritative sources such as the Saudi government agency publications, newspapers, international business journals. Other related periodicals based on the results from previous and current studies on similar topics were critically reviewed as well. Results - The findings of this paper show the different business environments of the Saudi market and the importance of various points regarding the company's global entry strategy even if the host market culture is quite different in many ways from other international markets. Conclusions - This case can provide Korean companies interested in the Middle East with insight into market penetration and global strategy, and present various perspectives and implications for global market access as well.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.21 no.7
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• pp.117-123
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• 2007

This paper is about the economic analysis of the replacement of electric facilities in the production facilities. As the interest of energy is increasing, the efficiency of facilities become more important. So, in this paper, we diagnosed facilities, especially electric motors, in the plant and calculated the operating efficiency, power loss with the load factor. And when we replace these facilities into high-efficiency motors, we also calculated new energy efficiency, energy loss and economic analysis through capital recovery factor. As a result, we economically proved that using high-efficiency motor is more beneficial than using non-high-efficiency motors in the model process.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.5 no.7
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• pp.1314-1320
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• 2001

DC motors have widely been used in the field of variable-speed driving system since it is easy to control flux and torque of the motors precisely but it is hard to check and maintain those periodically. In addition, there are difficulties in high power and high speed running due to rectifying limit of commutator, and are a lot of restrictions in installation. Therefore, speed control in BLDC(Brushless DC) motors have seriously been studied for a long while. In this paper, a mathematical model of BLDC motor driven by PWM inverter is developed. Dynamics and steady-state characteristics of BLDC motor are simulated and analyzed with a series of experiments for the parameter estimation : torque, speed, phase voltage and current.

• Journal of Power Electronics
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• v.12 no.4
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• pp.615-622
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• 2012

The switching frequency of the power electronic devices used in large synchronous motor drives is usually kept low (less than 1 kHz) to reduce the switching losses and to improve the converter power capability. However, this results in a couple of problems, e.g. an increase in the harmonic components of the stator current, and an undesired cross-coupling between the magnetization current component ($i_m$) and the torque component ($i_t$). In this paper, a novel complex matrix model of electrically excited synchronous motors (EESM) was established with a new control scheme for coping with the low switching frequency issues. First, a hybrid observer was proposed to identify the instantaneous fundamental component of the stator current, which results in an obvious reduction of both the total harmonic distortion (THD) and the low order harmonics. Then, a novel complex current controller was designed to realize the decoupling between $i_m$ and $i_t$. Simulation and experimental results verify the effectiveness of this novel control system for EESM drives.