• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2006.05a
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• pp.243-246
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• 2006

In this paper, Experimental results on the measurement of mechanical properties of fine patterns in the MEMS structure are described. The mechanical properties of embossing patterns on metallic thin foil is measured using the nano indentation system, that is developed by Korea Institute of Industrial Technology(KITECH). These micro embossing patterns are fabricated using CIP(Cold Isostatic Press) process on micro metallic thin foils(Al-1100) that are made by rolling process. These embossing patterned metallic thin foils(Al-1100) are used in the reflecting plate of BLU(Back Light Unit) and electrical/mechanical MEMS components. If these mechanical properties of fine patterns are utilized in a design procedure, the optimal design can be achieved in aspects of reliability as well as economy.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.39 no.6
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• pp.545-556
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• 1990

A design method of a current source using 12-pulse phase-controlled rectifier (PCR) is presented. The critical inductance of the 12-pulse PCR is derived and it is shown that the critical inductance can be reduced using a current source. The control circuit of the 12-pulse PCR with an inner fast dynamic loop is proposed to give the frequency synchronism and to reduce the subharmonics due to the unbalance of the transformer of the power line. This circuit is analyzed and its dynamic loop is optimized. The optimal constant PIMF (proportional, integral and measurable variable feedback, and feedforware) controller is also designed using the time-weighted quadratic performance index. It is shown via experimental results that the proposed design method gives high dynamic and static performance of the current source using the 12-pulse PCR.

• 유체기계공업학회:학술대회논문집
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• 2001.11a
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• pp.54-60
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• 2001

In this research, we developed a computer code that designs a compressor impeller, which serves as an essential component of a vacuum cleaner, and predicted its performance. The TEIS model originally developed by Japikse(1985), and the mean line analysis m combined to design the centrifugal impeller optimally. In this program the inlet geometry is designed by using the mean line analysis, and with assumption of resonable exit blade angle, the optimal geometry is searched by means of TEIS model and iterative scheme. The performance of designed impeller was compared with experimental data, and the far-field noise by the rotating impeller is also predicted.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.9
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• pp.895-899
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• 2014

This paper presents the balancing control of a unicycle robot using air power. Since the robot has one wheel to move forward and backward, the balancing control is quite challenging. To control the balancing angle, the accurate angle estimation by a tilt and a gyro sensor is required a priori. A complementary filter is implemented to eliminate the defects of two sensors and to fuse together to estimate an accurate balancing angle. The optimal design of air ducts is found empirically. Experimental studies of the balancing control of a unicycle robot confirm that the robot is well regulated without falling down.

• Proceedings of the KSME Conference
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• 2003.04a
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• pp.998-1002
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• 2003

This paper investigates the characteristics of stiffness and load in the thrust bearing of spindle which could be changeable according to the groove shape of inlet, in order to design a high-stiffness air bearing by selecting a optimal groove shape. In experiments, dead weight and displacement sensor are used to measure the load carrying capacity and the stiffness respectively. Various shapes and different depth of groove of self-restrictor are used as experimental conditions. Comparative study between the theoretical value and the practical one by measuring the value of stiffness and load of the thrust bearing is performed.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.12 no.6
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• pp.36-43
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• 2003

In machining of ceramic materials, they are very difficult-to cut materials because of there high strength and hardness. Machining of ceramics are characterized by cracking and brittle fracture. Generally, ceramics are machined using conventional method such as finding and polishing. However these processes are generally costly and have low MRR(material removal rate). This paper focuses on determining the optimal levels of process parameters for products with CNC machining center. For this purpose, the optimization of cutting parameters is performed based on experimental design method. A design and analysis of experiments is conducted to study the effects of these parameters on the surface roughness by using the S/N ratio, analysis of ANOVA and F-test. Cutting parameters, namely, cutting speed, feed and depth of cut are optimized with consideration of the surface roughness.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.6 s.249
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• pp.698-704
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• 2006

This paper presents an electrode shape design method for the multi-mode sensors that could deteict the selected structural multiple modes. The structure used for this study is an isotropic cantilever beam type with a PVDF (polyvinylidene fluoride) which is bonded onto the structure as a sensor. The shape optimization problem is solved by using Genetic Algorithm (GA) with an appropriate objective function. The performance of analytical optimal shape sensor is compared with that of experimental work. The results show that the, obtained electrode shape sensors have good performance to detect the multiple vibration modes simultaneously.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.9
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• pp.796-803
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• 2008

Ultrasonic testing uses the directivity of the ultrasonic wave, which propagates in on direction. The directivity is expressed as the relationship between the propagate direction and its sound pressure. The directivity of an ultrasonic wave is related to the choice of probe arrangement, testing sensitivity and scanning pitch and correct measurement of defect size and location. This paper describes on the directivity measurement of ultrasonic wave using the visualization method. The directivity of shear wave emitted from the angle beam transducer were constant during propagation. The difference of directivity was existed between 2 MHz and 4 MHz angle beam transducers. When these experimental results were compared with the theory which was based on the continuous wave, it showed good agreement with theoretical directivity on the principal lobe.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2001.05a
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• pp.103-108
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• 2001

The structure of hard disk drive(HDD) is excited by dynamic motion of a disk-spindle motor, and it makes sound noise. Therefore, the cover and the base of HDD should be designed to reduce noise and vibration induced by spindle motor. The prediction technique of sound pressure level(SPL) of a given structural shape enables us to design a cover and a base with much less vibration and noise. In this paper, we measured the force of disk-spindle motor and predicted SPL from HDD by computational simulation. To get a SPL of HDD by computational simulation, modal analysis and forced vibration analysis were performed with ANSYS, and sound radiation was computed using SYSNOISE. The calculated results were compared with experimental results and a good agreement was obtained. With this computer simulation procedure and design of experiment(DOE), optimal thickness of noise barrier and damper was calculated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.925-930
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• 2004

This paper is to study vibration effects of the dynamic vibration absorber. Multi-body dynamic analysis is carried out for the vehicle driveline model using ADAMS with flexible propeller shaft attached with the vibration damper. Primary bending mode frequency of the propeller shaft is obtained from the simulation and coincides with the experimental result. Various design parameters are studied in dynamic simulation operated by the engine torque input. This paper identifies the responses of dynamic vibration absorbers in the driveline with propeller shaft, which will be used to find out optimal design parameters.