• Proceedings of the KIEE Conference
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• 2006.07b
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• pp.1014-1015
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• 2006

In this paper, a new single phase voltage sag/swell compensator using direct power conversion is introduced. A new compensator consists of input/output filter, series transformer and direct at-ac converter, which is a single-phase back-to-back PWM converter without dc-link capacitors. Advantages of the proposed compensator include: simple power circuit by eliminating dc-link electrolytic capacitors and thereby, improved reliability and increased life time of the entire compensator; simple PWM strategy to compensate voltage sag/swell at the same time and reduced switching losses in the ac-ac converter. Further, the proposed scheme is able to adopt simple switch commutation method without requiring complex four-step commutation method commonly required in the direct power conversion. Simulation results are shown to demonstrate the advantages of the new compensator and PWM strategy.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.02a
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• pp.632-632
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• 2013

We generated single-crystal organic nanowire arrays using a direct printing method (liquidbridge- mediated nanotransfer molding) that enables the simultaneous synthesis, alignment and patterning of nanowires from molecular ink solutions. Using this method, single-crystal organic nanowires can easily be synthesized by self-assembly and crystallization of organic molecules within the nanoscale channels of molds, and these nanowires can then be directly transferred to specific positions on substrates to generate nanowire arrays by a direct printing process. The position of the nanowires on complex structures is easy to adjust, because the mold is movable on the substrates before the polar liquid layer, which acts as an adhesive lubricant, is dried. Repeated application of the direct printing process can be used to produce organic nanowire-integrated electronics with twoor three-dimensional complex structures on large-area flexible substrates. This efficient manufacturing method is used to fabricate all-organic nanowire field-effect transistors that are integrated into device arrays and inverters on flexible plastic substrates.

• Proceedings of the Korean Vacuum Society Conference
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• 2013.08a
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• pp.266.1-266.1
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• 2013

Large-scale single-crystal organic nanowire arrays were generated using a direct printing method (liquidbridge- mediated nanotransfer molding) that enables the simultaneous synthesis, alignment and patterning of nanowires from molecular ink solutions. Using this method, single-crystal organic nanowires can easily be synthesized by self-assembly and crystallization of organic molecules within the nanoscale channels of molds, and these nanowires can then be directly transferred to specific positions on substrates to generate nanowire arrays by a direct printing process. Repeated application of the direct printing process can be used to produce organic nanowire-integrated electronics with two- or three-dimensional complex structures on large-area flexible substrates. This efficient manufacturing method is used to fabricate all-organic nanowire field-effect transistors that are integrated into device arrays and inverters on flexible plastic substrates.

• Journal of the Semiconductor & Display Technology
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• v.17 no.3
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• pp.100-103
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• 2018

Due to the plasma applied from the outside, which acts as an etchant during the etching process, considerable heat is transferred to the wafer and a separate cooling process is performed to effectively remove the heat after the process. In this case, a direct cooling method using a refrigerant is suitable for cooling through effective heat exchange. The direct cooling method using the refrigerant using the latent heat exchange is superior to the cooling method using the sensible heat exchange. Therefore, in this paper, AMESim is used to design a direct refrigerant cooling system using latent heat exchange simulator was built.The constructed simulator is reliable compared with the actual experimental results. It is expected that this simulator will help to design and search for optimal process conditions.

• Structural Engineering and Mechanics
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• v.11 no.3
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• pp.325-340
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• 2001

This paper addresses an efficient modification method that eliminates the undesirable effects of strains due to various non-conforming modes so that the non-conforming element can pass the patch test unconditionally. The scheme is incorporated in the element formulation to establish new types of non-conforming hexahedral elements designated as NHx and NVHx for the regular element and variable node element, respectively. Non-conforming displacement modes are selectively added to the ordinary (conforming) element displacement assumptions to improve the bending behavior of the distorted solid element. To verify the validation of proposed direct modification method and the improvement of element behavior, several numerical tests are carried out. Test results show that the proposed method is effective and its applications to non-conforming solid elements guarantee for the element to pass the patch test.

• Journal of Biomedical Engineering Research
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• v.22 no.3
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• pp.223-229
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• 2001

In this paper, we have compared the direct fan-beam reconstruction method with the rebinning method in terms of computation time and spatial resolution using computer simulation. As a result, the direct fan-beam method is superior to the rebinning method in the spatial resolution though the former needs longer computation time. However, if we adopt the quarter-detector-offset technique to improve the spatial resolution, the rebinning method outperforms the direct fan-beam method. The computation times have been evaluated using the fast algorithms optimized to reduce the number of interpolation calculations at the back-projection, and the spatial resolutions have been compared using the computer generated phantoms.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.498-501
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• 2004

A new slab design using secant stiffness, Direct Inelastic Slab Design, was developed. Since basically the proposed design method uses linear analysis, it is convenient and stable in numerical analysis. At the same time, the proposed design method can accurately estimate the inelastic strength and ductility demands of slab because it can analyzes the inelastic behavior of structure using iterative calculations for secant stiffness. In the present study, the procedure of the proposed design method was established, and a computer program incorporating the proposed method was developed. Design examples using the proposed method were presented, and compared with traditional nonlinear analysis, and experiments. The Direct Inelastic Slab Design, as an integrated analysis/design method, can directly address the design strategy intended by the engineer, such as moment strength and ductility limit. As a result, economical and safe design can be achieved.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.25 no.12
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• pp.1228-1235
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• 2014

Input impedance of UHF RFID tag chip is needed to design a tag. In determining the chip impedance, direct measurement method is adopted commonly. In this paper, problems generated from fixtures that interface between tag chip and coaxial-oriented measurement instrument are investigated and the result of the problems is shown, when the direct measurement method is applied. As an alternative to the method, a modeling method is proposed and its validity and accuracy are shown.

• Journal of KSNVE
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• v.8 no.2
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• pp.274-282
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• 1998

A systematic procedure for designing a direct-radiator-type loudspeaker has been developed, based on the numerical vibro-acoustic analysis and the Taguchi method. The finite-element model of the speaker cone has been used to calculated the vibration response of the cone excited by the voice coil. The vibration displacement of the speaker cone has been converted into the vibration velocity and used as a boundary condition for the acoustic analysis. The acoustic frequency characteristics of the loudspeaker have been calculated by the boundary element method. The numerical results have been verified by the experiments carried out in an anechoic chamber. Some design parameters have been selected by using the Taguchi method, and the variations of the acoustic characteristics due to the changes of the parameter values have been examined using the numerical model.

• Journal of Mechanical Science and Technology
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• v.17 no.12
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• pp.1986-1993
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• 2003

The spatially resolved spray volume fractions from both line-of-sight data of direct measuring cells and a laser diffraction particle analyzer (LDPA) are tomographically reconstructed by the Convolution Fourier transformation, respectively. Asymmetric sprays generated from a twin-hole injector are tested with 12 equiangular projections of measurements. For each projection angle, a line-of-sight integrated injection rate was measured using a direct sampling method and also a liquid volume fraction from a set of line-of-sight Fraunhofer diffraction measurements was measured using a light extinction method. Interpolated data between the projection angles effectively increase the number of projections, significantly enhancing the signal-to-noise level in the reconstructed data. The reconstructed volume fractions from the direct sampling cells were used as reference data for evaluating the accuracy of the volume fractions from the LDPA.