• Journal of Powder Materials
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• v.19 no.1
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• pp.67-71
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• 2012

The present paper gives an overview about the Atom Probe Tomography technique and its application to powder materials. The preparation of needle-shaped Atom Probe specimens from a single powder particle using focused-ion-beam milling is described. Selected experimental data on mechanically alloyed (and sintered) powder materials are presented, giving insight into the atomic-scale elemental redistribution occurring under powder metallurgical processing.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2004.05a
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• pp.429-432
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• 2004

Multidisciplinary design optimization technique is applied to drum type washer in order to minimize the vibration of the cabinet. Dynamic analysis and structural analysis are carried out by using commercial programs to obtain the reliable responses. Analysis models are compared to the experimental responses and finally validated for further design. Two commercial programs are integrated by the design framework EMDIOS that provides interfaces to conveniently link between analyzers and performs design optimization. In this research we could obtain an optimum design that reduces the magnitude of amplitude by about 33% compared with the original design.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.708-713
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• 2007

Finite element model updating has been performed using an optimization technique in the paper. The objective function consists of natural frequencies, modal assurance criterion values, and bandwidths of modes, which are obtained from finite element analysis and experiment. Young's modulus and damping coefficient of the material are selected as design variables whose values are modified to make the objective function as small as possible. To consider the loading effect of an accelerometer, its mass and moment of inertia are added to design variables. This model updating method has been applied to a cantilever beam, and experimental data are measured by modal test.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.24 no.8
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• pp.636-642
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• 2014

The sensor configuration of the magnetostrictive guided wave system can be described as a single continuous transducing element which makes it difficult to separate the individual modes from the reflected signal. In this work we develop the mode decomposition technique employing chirplet transform, which is able to separate the individual modes from dispersive and multimodal waveform measured with the magnetostrictive sensor, and to estimate the time-frequency centers and individual energies of the reflection, which would be used to locate and characterize defects. The reflection coefficients are calculated using the modal energies of the separated mode. Results from experimental results on a carbon steel pipe are presented, which show that the accurate and quantitative defect characterization could become enabled using the proposed technique.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.53 no.12
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• pp.700-708
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• 2004

Flux-reversal machine (FRM) is a new doubly-salient stator-permanent magnet (PM) machine with flux linkage reversal in the stator concentrated windings. It can operate in both motoring and generating modes. In this paper, a novel design technique to improve the performance of FRM is proposed. Proposed techniques have a new stator winding and a magnet arrangement method. The stator and rotor shape with a concave type and a flux barrier are also proposed. According to the experimental results, it is shown that the proposed FRM have an improved performance.

• Journal of the Korean Institute of Telematics and Electronics D
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• v.35D no.4
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• pp.18-23
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• 1998

Approximations inherent in the Cohn synthesis theory, which is generally perferree as a convinient design technique for direct-couple waveguide filter, results in considerable devications from the required responses as the design bandwidth increases. In this paper, two main deviations likely to occur in practice are examined using the mode-matching technique. They are a shift in couoff frquencies and large return loss occuring near coutoff frequencyles. Using the power loss ratio, the first effect is corrected to the resulant filter structure from cohn synthesis. In order to show the validity of the intorduced approackes. Ka-band waveguide filter ahs been designed and manufactored. The experimental curve follow the expected curves after corrections fairly closly.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2012.05a
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• pp.247-250
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• 2012

As industrialization progresses is rapidly growing, the city of density and temperature is rising successively. It leads to the status of environmental issues. It is needed to develop process of planting concrete block using by Eco-materials for replacing to he existing rooftop light soil that imported. In this study, developing the process of planting lightweight block is researched on using applications of 6 Sigma technique. It makes process object improve standard by using statistical method. Also, there are suggestion that it is optimum mix design conditions and affection of experimental factors in matters of developing planting concrete block for rooftop greening.

• Design & Manufacturing
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• v.2 no.2
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• pp.1-5
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• 2008

Mechanical properties of the materials used for mold and industrial machinery under high strain rate loading conditions such as high impact loading are required to provide appropriate safety assessment to varying dynamically loaded mechanical structures. The Split Hopkinson Pressure Bar(SHPB) technique with a special experimental apparatus can be used to obtain the material behavior under high strain rate loading conditions. In this paper, the dynamic deformation behavior of a brass under high strain rate compressive loading conditions has been determined using the SHPB technique.

• Proceedings of the KIEE Conference
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• 2001.07e
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• pp.90-94
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• 2001

The aim of this paper is twofold: The one is to design BLDC motors for an electric bicycle and the other is to develop a controller of the BLDC motors. A new BLDC Motor has a permanent magnet rotor in which the magnetic arrangement is radial to the shaft and integral to the rotor laminations instead of mounted on the perimeter of the rotor. This technique concentrates flux, giving a higher flux density than a surface-mounted PM motor and has the increase of reluctance torque. The stator of BLDC motor has parallel winding instead of interconnected wye-connection winding, allowing multi-phase separate independent controllability. It gets much more high power than wye-connection at same low voltage. The proposed controller has a technique of exited with modulation(EWM) and one H-bridge and two photo sensors per phase. Experimental results show the performance of the proposed BLDC motors for an electric bicycle.

• Korean Journal of Computational Design and Engineering
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• v.16 no.2
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• pp.126-136
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• 2011

The existing approaches to freeform building construction cause many problems. However, recent BIM technique development based on parametric modeling method and improvement of freeform materials manufacturing technology using IT technology encouraged many advanced countries to try experimental projects. Thus, laser scanning technique is in the limelight as a new alternative in the field of freeform building construction and inspection. This study selected a domestic small freeform building and practiced laser scanning and as-planned modeling by using Reverse Engineering. Then each deviation was comparatively analyzed through figures which extracted data by numerically analyzing the newly modeled as-built and Excel spread sheet. Through the process, limits and follow-up research subjects are discussed as well.