• Journal of Korea Foundry Society
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• v.15 no.2
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• pp.156-163
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• 1995

Solidification of aluminum alloys under moderate pressures has been investigated. Interfacial heat transfer coefficient at the casting/mold interface varies with time after pouring the molten metal into the die cavity, and therefore plays an important role in determining solidification sequence. The heat transfer coefficients were evaluated by using an inverse problem method, based on the measured temperature distribution. The calculated heat transfer coefficients were used for solidification simulation in the squeeze casting process. The effects of applied pressure and positions of insulation in the mold have also been investigated on solidification microstructures and on the formation of macrosegregation of Al-4.5wt.%Cu alloys.

• Journal of the Korean Magnetics Society
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• v.5 no.2
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• pp.112-114
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• 1995

We show physically and mathematically that magnetoelastic coupling coefficients can be predicted to have a form of $B^{eff}=B^{b}+B^{s}/t$, sirniiarily in effective magnetic anisotropy energy in ultrathin films. The inverse thickness dependnce of magnetoelastic coupling coefficients implies lots of technical potentials.

• Proceedings of the KIEE Conference
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• 1995.07c
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• pp.1095-1097
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• 1995

We studied on Solide Oxide Fuel cells, have some advantages of higher power density and less cost for power-supply. Recently, Ni-YSZ materials are used as anode of SOFC. If its contents of Ni is higher then its electronic conductivity is higher. And If it has inverse tendency then its ionic conductivity become higher. So in this experiments, we investicated the optimum content of Ni, by testing expansion coefficient, impedance characteristics, overvoltage.

• 한국신재생에너지학회:학술대회논문집
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• 2010.06a
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• pp.186.2-186.2
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• 2010

풍력발전기의 구성요소 중 브레이드는 바람의 운동에너지를 회전력으로 변환하는 핵심요소이며, 효율적인 설계기법이 절실히 요구되는데 선진국에서는 설계기술을 회피하는 실정으로 브레이드 형상 설계기법의 확보는 어려운 실정이다. 본 논문은 날개요소 운동량이론(BEMT) 및 X-foil을 이용하여 10kW급 브레이드 국산화 개발에 목적을 두고 공기역학적 설계를 수행하여 국내 풍황에 적합한 최적의 풍력발전기 에어포일을 개발하는데 목적을 두고 그 방안을 제시한다.

• Advances in materials Research
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• v.6 no.1
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• pp.27-43
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• 2017

The transient thermo-mechanical behavior of a simply-supported beam made of a functionally graded material (FGM) under the effect of a moving heat source is investigated. The FGM consists of a ceramic part (on the top), which is the hot side of the beam as the heat source motion takes place along this side, and a metal part (in the bottom), which is considered the cold side. Grading is in the transverse direction, with the properties being temperature-dependent. The main steps of the thermo-elastic modeling included deriving the partial differential equations for the temperatures and deflections in time and space, transforming them into ordinary differential equations using Laplace transformation, and finally using the inverse Laplace transformation to find the solutions. The effects of different parameters on the thermo-mechanical behavior of the beam are investigated, such as the convection coefficient and the heat source intensity and speed. The results show that temperatures, and hence the deflections and stresses increase with less heat convection from the beam surface, higher heat source intensity and low speeds.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.30 no.4 s.247
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• pp.387-392
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• 2006

This paper predicts the modified mass and stiffness of structure using the sensitivity coefficients with the iterative method. The sensitivity coefficients are obtained by the change of the eigenvectors according to structural modification. The method is applied to an examples of a 3 degree of freedom system by modifying mass and stiffness. The predicted mass and stiffness are in good agreement with these from the structural reanalysis using the modified mass and stiffness.

• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.1215-1218
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• 1998

본 논문은 Digital Audio Compression(AC-3) Standard 인 A-52를 기반으로 하였으며 Borland C++3.1 Compiler를 사용하여 AC-3 Decoding Algorithm 구현하였다. Input Stream은 DVD VOB File에서 AC-3 Stream만을 분리하여 사용하며 최종 출력은 16 Bit PCM File이다. AC-3의 Frame구조는 Synchronization Information, Bit Stream Information, Audio Block, Auxiliary Data, Error Check로 구성된다. Aduio Block 은 모두 6개의 Block으로 나뉘어져 있다. BSI와 Side Information을 참조하여 Exponent를 추출하여 Exponent Strategy에 따라 Exponent를 복원한다. 복원된 Exponent 정보를 이용하여 Bit Allocation을 수행하여 각각의 Mantissa에 할당된 Bit수를 계산하고 Stream으로부터 Mantissa를 추출한다. Coupling Parameter를 참조하ㅕ Coupling Channel을 Original Channel로 복원시킨다. Stereo Mode에 대해서는 Rematrixing을 수행한다. Dynamic Range는 Mantissa와 Exponent의 Magnitude를 바꾸는 것으로 선택적으로 사용할 수 있다. Mantissa와 Exponent를 결합하여 Floating Point coefficient로 만든 후 Inverse Transform을 수행하면 PCM Data를 얻을 수 있다. PC에서 듣기 위해서는 Multi Channel을 Stereo나 Mono로 Downmix를 수행한다. 이렇게 만들어진 PCM data는 PCM Data를 재생하는 프로그램으로 재생할 수 있다.

• Proceedings of the IEEK Conference
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• 2000.09a
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• pp.389-392
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• 2000

In this paper, we propose a novel post processing method of deconvolution for SAR images based on phase extension inverse filtering, which improves spatial resolution as well as effectively eliminates sidelobes with low computational complexity. It extends the bandwidth only to control the magnitude of the processed SAR data without distortions of the phase in frequency domain unlike the other techniques such as spatially variant apodization (SVA), and other deconvolution techniques. We compare the image processed by the proposed method with images processed by uniform weighting function, Hamming weighting function whose coefficient is 0.75, and SVA.

• Journal of Power System Engineering
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• v.15 no.4
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• pp.25-30
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• 2011

This study is made to provide with a method for correcting the geometric distortion of the digital radiography image by analytical approach based upon the inverse square law and Beer's law. This study is aimed to find out and improve a mathematic model of nonlinear type. Variations in the alignment of the X-ray source, the object, and imaging plate affect digital radiography images. A model which is expressed in parameter values; e.g, angle, position, absorption coefficient, length, width and pixel account of radiography source, is developed so as to match the sample image. For the best correction of the digital image that is the most similar to the model image, a correction technique based upon tangent is developed; then applied to the digital radiography images of steel tubes. As a result, the image correction is confirmed to be made successfully.

• Economic and Environmental Geology
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• v.33 no.2
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• pp.111-116
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• 2000

Indentifying anomaly correlations between data sets is the basis for rationalizig geopotential interpretation and theory. A procedure is presented that constitutes an effective process for identifying correlative features between the two or more geopotential data sets. Anomaly features that show direct, inverse, or no correlations between the data may be separated by applying filters in the frequency domains of the data sets. The correlation filter passes or rejects wavenumbers between co-registered data sets based on the correlation coefficient between common wavenumbers as given by the cosine of their phase difference. This study includes an example of Magsat magnetic anomaly profile that illustrates the usefulness of the procedure for extracting correlative features between the data sets.