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각 스펙트럼 영역에서 개선된 Newton 알고리듬을 이용한 완전도체의 역산란 방법
박선규,박정석,라정웅 대한전자공학회 1994 전자공학회논문지-A Vol.31 No.6
In this paper, an iterative inversion method in angular spectral domain is presented for microwave imaging of a perfectly conducting cylinder. Angular spectra are calculated from measured far-field scattered fields. And then both the propagating modes and the evanescent modes are defined. The center and initial shape of an unknown conductor may be obtained by the characteristics of angular spectra and the total scattering cross section (TSCS). Finally, the orignal shape is reconstructed by the modified Newton algorithm. By using well estimated initial shape the local minima can be avoided, which might appear when the nonlinear equation is solved with Newton algorithm. It is shown to be robust to noise in scattered fields via numerical examples by keeping only the propagating modes and filtering out the evanescent modes.
박선규 대한건축학회지회연합회 2011 대한건축학회연합논문집 Vol.13 No.4
Demolition waste generation has exceedingly increased in the world, including korea. It is estimated the approximately 115 thousand tons of waste concrete are occurred in 2009 in this country. And it is estimated that the waste concrete will be more generated more each year than those of today. Therefore, it is necessary to use waste concrete for aggregate of concrete. Many studies have been conducted to reuse of recycled aggregate for construction materials. To make use of recycled aggregate, the elastic modulus of recycled aggregate concrete must bo assured. The purpose of this study is to predict elastic modulus of recycled aggregate concrete using neural network which was applied to predict properties of engineering problems. New learning algorithms for the prediction on the elastic modulus of recycled aggregate concrete is proposed focusing on input layer components and a normalization method for input data and their validity is examined through elastic modulus data of recycled aggregate concrete. In artificial neural network algorithm, the main input data to be trained are the water content, fine and coarse aggregate ratios, curing temperature of recycled aggregate concrete, water/cement ratios and etc. Through this study, it was confirmed that artificial neural network successfully predict the elastic modulus of recycled aggregate concrete.
박선규 成均館大學校 科學技術硏究所 1997 論文集 Vol.48 No.1
콘크리트의 압축강도와 인장강도는 철근콘크리트 구조물의 설계에서 뿐만 아니라, 토목·건축 구조물의 연구에 있어서도 가장 중요한 위치를 차지하고 있다. 같은 종류의 콘크리트라 하더라도 인장강도는 공시체의 모양, 타설방법, 양생조건 등에 상당히 민감하기 때문에 압축강도보다 더욱 더 큰 편차를 보이고 있다. 현재까지 콘크리트의 압축강도와 인장강도(순인장강도, 휨인장강도, 할열강도)사이의 상관관계를 찾기 위한 다방면의 실험과 연구가 계속되고 있지만 서로 약간의 차이를 보여 주고 있다. 본 연구에서는 실험을 통하여 콘크리트의 압축강도와 인장강도(순인장 강도, 휨인장강도, 할열강도, 비틀림강도) 간의 상관 관계를 고찰하고, 특히 각 공시체의 단면 형상에 따르는 비틀림인장강도의 영향을 연구하였다. The comprssive and tensile strengths of concrete are the most importantfacturs even in the study of normal structures as well as the design of reinforced concrete structures. Since the tensile stregth is very sensitive to mould, casting method, curing condition and so on. Various studies and experiments have been progressed to obtain the correlation between the compressive strength and the tensile strengths such as pure, bending tensiles and split strength of concrete. Each result shows a little difference. In the present study, the correlation between the compressive and tensile strengths is investigated through the experimental studies. The influence of torsional tensile strength is also considered in the section of mould.
박선규,이성래,조원일,조병원 대한금속·재료학회 2010 METALS AND MATERIALS International Vol.16 No.1
We studied the dependence of Al2O3 coating thickness and annealing conditions on the surface morphology and electrochemical properties of Al2O3 coated LiCoO2 films. The optimum coating thickness allowing for the highest capacity retention was about 24 nm. A sample consisting of Al2O3 coated on annealed LiCoO2film with additional annealing at 400 °C had a uniform coating layer between the coating materials and cathode films. This sample showed the best capacity retention of ~91 % with a charge-cut off of 4.5 V after 30 cycles,while the bare cathode film showed a capacity retention of ~32 % under the same conditions. The formation of second phases such as Co-Al-O was observed in the coating films by X-ray photoelectron spectroscopy (XPS). The Co-Al-O containing samples showed a higher initial capacity because of their smaller grain size,but less capacity retention than the Al2O3 containing samples.