• Transactions of the Korean Society of Mechanical Engineers A
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• v.24 no.6 s.177
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• pp.1427-1437
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• 2000

In the authors＇ preceeding paper, an improved component mode synthesis (CMS) technique in which experimental data as well as finite-element data are available in sub-systems has been proposed. Thi s technique, called an improved experimental free-interface method (IEFIM), has been proved to be more accurate and more efficient than the conventional experimental CMS method based on McNeal's formulation. It is due to the facts that dynamic residual terms as well as static ones are compensated from experimentally obtained FRFs and that FRFs measured on any frequencies can be used for the compensation. In this paper, the technique is applied to the component mode synthesis of a car body structure. As a result, the applicability of the technique to a large structure is demonstrated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.719-724
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• 2002

Impact hammer is widely used as a convenient excitation tool in structural modal testing though, little is known about the dynamic characteristics of its impulse mechanism. Transmission of the impulsive force to the structure depends m the dynamic properties of the impact hammer as well as the stiffness of the tip. In this study an improved dynamic model of the impact hammer is proposed with the consideration of structure to be tested. The deformation masses of hammer tip and structure are as well as their contact stiffness. Numerical results show that this model is useful for the prediction of the impulse duration and the condition of rebounce..

• Journal of the Korean Institute of Telematics and Electronics A
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• v.29A no.1
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• pp.19-24
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• 1992

The analysis of the resonant tunneling based on the exact solution of Schrodinger equations is performed in a single quantum well structure under applied bias. The transmittivity and the net tunneling current density are calculated with Airy function and the boundary conditions which is suggested by Bastard. The results are compared with those from other methods and boundary conditions. From the calculated J-V characteristics for the tunneling current, the dependence of the voltage location showing the first peak current on the various temperatures and Fermi level is investigated. In addition, the wave function within the structure is obtained and compared with that from the flat-potential model.

• Proceedings of the Korea Society of Poultry Science Conference
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• 2005.11a
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• pp.82-83
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• 2005

Recently, layer industry shows the decrease in the number of farm and increase in rearing scale in both Korea and Japan. Seventy percent of layer farms in Japan feed more than 50,000 birds per each farm but in Korea, only 19.3% of layer farms are feeding more than 30,000 birds which covers 59% of total chicken number. This tendeney will be more accellerated from now on. Brand egg Production in Japan is developed with the involvement of farmers, sailers feed companies and also the marketing structure of brand egg is well organised in between farmers and consumers. However in Korea, the marketing structure of brand egg is not well settled for this reason the egg price is often decided lower much price than regrnlar price by the intermediate dealers. Under this kind of tough situation, Korean layer farmers are stressed to develop new brand products such as functional egg, settle the sales and distribution network with the good cooperation of farmers, and distributers.

• Journal of Magnetics
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• v.9 no.2
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• pp.65-68
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• 2004

Magnetically soft nanomaterials obtained by controlled crystallisation of metallic glasses are the newest group of materials for inductive components. In particular, research is carried out in the field of alloys for high temperature applications. This kind of materials must meet two basic requirements: good magnetic properties and stability of properties and structure. In the present work the magnetic properties and structure of Fe-Co-Hf-Zr-Cu-B (HIDTPERM-type) alloys were investigated, as well as their stability. Differential thermal analysis, (DTA), X-ray diffractometry (XRD), transmission electron microscopy (TEM), magnetometry (VSM) and quasistatic hysteresis loop recording were used to characterise structure and properties of the alloys investigated. Optimisation against properties and their stability was performed, resulting in formulation of chemical composition of the optimum alloy, as well as its heat treatment.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.09a
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• pp.364-372
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• 2001

An orifices fluid damper(OFD) having the capacity of about 2 tons was designed and fabricated and applied to a 6-story steel structure under random excitation and seismic excitation for the confirmation of its validity on structural vibration absorbtion. The experimental results demonstrated that the addition of an OFD to the test structure is very effective in reduction of vibration level of the higher modes as well as the fundamental mode. Maxwell model was adopted to described the frequency-dependent characteristics of the fabricated OFD and the numerical simulation was carried for the test structure. It was confirmed that the experimental and numerically simulated results agree well.

• Journal of Power System Engineering
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• v.13 no.5
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• pp.34-39
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• 2009

In this paper, the CFD analysis using various turbulent models has been performed to evaluate which type of turbulent models can predict well the mixing flow structure of $45^{\circ}$ impinging round jet. This CFD analysis has been carried out through the commercial Fluent software. As a result, any of turbulent models cannot predict the experimental results definitely all over the flow range. However, as compared with the experimental results, the turbulent model of realizable(RLZ) k-$\varepsilon$ only predicts well in the limited range between X/$X_0=1.1$ and X/$X_0=2.0$.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.6
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• pp.469-477
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• 2002

An orificed fluid damper(OFD) having the capacity of about 2 tons was designed and fabricated, and series of tests were performed to grasp the fundamental performance characteristics of it. Several important findings were observed and introduced in this paper. It was applied to a 6-story steel structure under random excitation and seismic excitation for the confirmation of its validity on structural vibration absolution. The experimental results demonstrated that the addition of an OFD to the test structure is very effective in reduction of vibration level of the higher modes as well as the fundamental mode. Maxwell model was adopted to describe the frequency-dependent characteristics of the fabricated OFD and the numerical simulation was carried for the test structure. It was confirmed that the experimentally and numerically simulated results agree well.

• Transactions of Materials Processing
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• v.9 no.1
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• pp.10-16
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• 2000

This research investigates microstructures and fatigue properties of the weldments of 6005A aluminum alloy developed for railroad vehicles. The samples were extruded into a truss structure and welded together using the gas metal arc welding process. The extruded sample showed a wide variation in grain size, possibly due to the frictional heating as well as the inghomogeneous metal flow in the extrusion die. The mechanical properties of the samples were affected by the mirocstructures. The fatigue strength of the welded structure was found to decrease significantly from that of the base metal. It was found that the fatigue characteristics of the welded structure were determined by the microstructure of the parent metal as well as weld defects such as porosities and the liquation cracks.

• ETRI Journal
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• v.38 no.6
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• pp.1104-1113
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• 2016

Non-linear document navigation refers to the process of repeatedly reading a document at different levels to provide an overview, including selective reading to search for useful information within a document under time constraints. Currently, this function is not supported well by small-screen tablets. In this study, we propose the concept of structure-aware touch-based scrolling (SATS), which allows structural document navigation using region-dependent touch gestures for non-sequential navigation within tablets or tablet-sized e-book readers. In SATS, the screen is divided into four vertical sections representing the different structural levels of a document, where dragging into the different sections allows navigating from the macro to micro levels. The implementation of a prototype is presented, as well as details of a comparative evaluation using typical non-sequential navigation tasks performed under time constraints. The results showed that SATS obtained better performance, higher user satisfaction, and a lower usability workload compared with a conventional structural overview interface.