• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.488-490
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• 1994

To meet the requirements of high performance and reliability as a industrial motor drive, we developed an integrated oil-line fault diagnosis and monitoring system which consists of DSP-based controller and PC-based MMI (Man-machine interface) program. The dedicated controller performs real-lime fault detections and protections. The MMI program monitors the on-line fault status of the drive system and offers full explanations of the fault name(WHAT?), deducible causes of the fault operation(WHY?), and chock points (HOW?) based upon the experiences of the expert. Also the TRACE data which was stored just before and after the accident can be scrutinized using MMI tools.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.4
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• pp.166-174
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• 2002

Power steering systems far automobile are becoming ever more popular because they reduce steering efforts of the drivers, especially during parking lot maneuver. In this paper, the controller of the motor driven hydraulic power steering(MDHPS) has been designed and developed. This system uses a power source of DC motor instead of engine power source for power steering drive oil pump. The developed MDHPS system is accomplished a highly sensitive power steering resulted from electronic control under variable driving condition. Furthermore, this system is more improvement than type of engine driving far fuel economy.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.2649-2651
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• 2005

In trains driven by electric motor, when the adhesion force between rail and driving wheel decreases suddenly, the electric motor coach has slip phenomena. The characteristics of adhesion force coefficient are strongly affected by the conditions between rails and driving wheels, such as moisture, dust, and oil on the rails and so on. This paper proposes the vector control structure for the improved re-adhesion control with paralleled control of induction motors under the sudden variation of the adhesion force.

• Proceedings of the KIEE Conference
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• 2006.07d
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• pp.1879-1880
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• 2006

In electric motor coaches, when the adhesion force between rail and driving wheel decreases suddenly, the electric motor coach has slip phenomena. The characteristics of adhesion force coefficient is strongly affected by the conditions between rails and driving wheels, such as moisture, dust, and oil on the rails and so on. This paper proposes the simulation system for slip & slide test using virtual train. We can easily research the adhesion characteristics and adhesion control method with this equipment under the sudden variation of the adhesion force coefficient.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.530-532
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• 2002

This paper presents an optimum design of herringbone grooved journal bearing for spindle motor of hard disk drive (HDD) system. In addition to the conventional “rectangular” groove, various groove profiles are designed. The stiffness and damping coefficients of the oil film and frictional torque are calculated and compared for tile various groove profiles. The “circular”, “valley”, and “reversed saw tooth” grooves do not produce high direct stiffness, since they partly increase the groove depths in the direction of lubricant flow, causing to reduce the pumping action of the bearing. The maximum direct stiffness can be obtained by the “rectangular”, “saw tooth”, and “step” grooves. With the same cross sectional area of the grooves, these three grooves have the same maximum stiffness, damping coefficients, and frictional torque. Among these recommendable grooves, the saw tooth groove may keep its original profile for long, enduring metal-to-metal contact during startup and shutdown.

• 유체기계공업학회:학술대회논문집
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• 2003.12a
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• pp.315-322
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• 2003

High performance turbo compressor, Turbo Master, was successfully developed by applying combined technology and experience based on aero gas turbine engines. The Turbo Master, developed using our own technology, was designed for high performance and reliability And the Turbo Master will supply absolutely oil-free compressed air to your facilities. In special, a next-generation micro compressor was lately developed, using air foil bearing and high speed motor known as the latest high technology.

• Journal of Power Electronics
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• v.19 no.3
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• pp.714-726
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• 2019

This paper proposes a hybrid-boost Modular Multilevel Converter (MMC) for the Medium-Voltage (MV) Variable Speed Drives (VSDs) employed in subsea applications, such as oil and gas recovery. In the presented architecture, a hybrid-boost MMC with a reduced number of semiconductor devices driving a multiphase Induction Machine (IM) is investigated. The stepped output voltage generated by the MMC reduces or eliminates the filtering requirements. Moreover, the boosting capability of the proposed architecture eliminates the need for bulky low-frequency transformers at the converter output terminals. A detailed illustration of the hybrid-boost MMC operation, the expected limitations/constraints, and the voltage balancing technique are presented. A simulation model of the proposed MV hybrid-boost MMC-based five-phase IM drive has been built to investigate the system performance. Finally, a downscaled prototype has been constructed for experimental verification.

• Journal of Microbiology and Biotechnology
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• v.28 no.1
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• pp.95-104
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• 2018

Biosurfactants or microbial surfactants are surface-active biomolecules that are produced by a variety of microorganisms. Biodegradability and low toxicity have led to the intensification of scientific studies on a wide range of industrial applications for biosurfactants in the field of environmental bioremediation as well as the petroleum industry and enhanced oil recovery. However, the major issues in biosurfactant production are high production cost and low yield. Improving the bioindustrial production processes relies on many strategies, such as the use of cheap raw materials, the optimization of medium-culture conditions, and selecting hyperproducing strains. The present work aims to obtain a mutant with higher biosurfactant production through applying mutagenesis on Bacillus subtilis SPB1 using a combination of UV irradiation and nitrous acid treatment. Following mutagenesis and screening on blood agar and subsequent formation of halos, the mutated strains were examined for emulsifying activity of their culture broth. A mutant designated B. subtilis M2 was selected as it produced biosurfactant at twice higher concentration than the parent strain. The potential of this biosurfactant for industrial uses was shown by studying its stability to environmental stresses such as pH and temperature and its applicability in the oil recovery process. It was practically stable at high temperature and at a wide range of pH, and it recovered above 90% of motor oil adsorbed to a sand sample.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.676-678
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• 2002

This paper deals with the design and characteristic analysis of a coreless an axial flux permanent magnet (AFPM) motor. Axial-flux permanent magnet motors prove to be the best candidate for application in electric vehicles (EVs) as direct-drive wheel motors, as in comparison with conventional motors they allow design with higher compactness, lightness and efficiency. Recently, issues regarding environment and the diversification of dependence in oil are watched with keen interest. In this theses, through the simulation of AFPM for low and high torque which has stator in the center and two rotors each side, understand its specialty, with this, make a prototype motor and design drive which can enhance the motors stability in low speed. Especially, specialty of motors torque power output will be mainly talked and based on this, possibility of application in EVs will be inspected by the theoretical study and the test.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• v.9 no.1
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• pp.947-950
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• 2005

For revolving and elevating a turret of a tank, we substitute an existing oil pressure system with an electric system using a motor and applied the vector control method to this system. A switching method of an inverter for providing desired sinusoidal current to each phase of a motor, we adopted min-max pulse width modulation method which takes less computation time, rather than space vector pulse width modulation method. We designed a digital filter and applied it to the control system. Developed current controller is verified it's performance through a current control test, speed control test, frequency response and tracking a profile of speed test.