• Computational Structural Engineering
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• v.3 no.3
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• pp.101-111
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• 1990

The elastic analysis of floor slabs using the p-version of finite element method encounters stress singularities at certain types of reentrant corners, openings and cut-outs. Results obtained using the computer code based on C.deg. - hierarchic plate element formulated by Reissner-Mindlin theory are compared with theoretical predictions and with computational results reported in the literature. The convergence rate of h-, p- and hp-version can be estimated on the basis of the energy norm in global sense. If accuracy in terms of the number of degree-of-freedom is used as a criterion, the solutions presented here are the most efficient that have been published up to date. Examples are the rhombic plate with the obtuse angle of 150.deg. and the square plate with cut-outs.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.3
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• pp.325-331
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• 2011

A new method to predict the proper promotion time on the near-step-temperature test profile when heating or cooling the test-piece in a test chamber to the test temperature for environmental tests has been proposed by using the lumped analysis. For a given test condition the analysis shows the existence of a promotion time that reduces the testing time and saves energy. The theoretical results are in reasonably good agreements with experimental results for steel specimens. The suggested promotion time is approximately proportional to the mass/surface area of the test-piece for a given material.

• Journal of the Korean Magnetics Society
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• v.10 no.3
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• pp.139-142
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• 2000

We present results based on FLAPW local spin density(LSD) calculations of double perovskite structure oxide L $a_2$MnFe $O_{6}$ . The total energy calculations with various spin structures show that this material has a stable ferromagnetic spin configuration. The ionic state of transition metals depend on the spin configuration $_Mn^{4+}$ and F $e^{2+}$ for ferromagnetic structure, M $n^{3+}$ and F $e^{3+}$ for ferrimagnetic structure). It is explained by super exchange interaction between transition metals. The calculated magnetic structure is well matched with recent experimental result.ult.t.

• Journal of the Korean Chemical Society
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• v.30 no.2
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• pp.172-180
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• 1986

The Hammett's substituent constants were analyzed for the substituted-benzoic acid, -benzene and -naphthalene by LCAO MO method. Hammett's ${\sigma}$-values have been theoretically proved to treat as the sum of independent contribution of inductive effect and resonance effect. That is, Is (static inductive effect) and Id (dynamic inductive effect) corresponding to inductive effect are chosen as net charge and approximate self atom polarizability indices respectively, and ${\Delta}E^{HOMO}$ which is the difference in HOMO energy level between substituted molecule and unsubstituted molecule as resonance effect. In conclusion, it has been found that the observed ${\sigma}$-values depend on the sum of Id, Is and ${\Delta}E^{HOMO}$.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.8
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• pp.238-244
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• 2013

In energy dispersive X-ray fluorescence analysis, the removal of the continuum on which the X-ray spectrum is superimposed is one of the most important processes, since it has a strong influence on the analysis result. The existing methods which have been used for it usually require tight constraints or prior information on the continuum. In this paper, an efficient background correction method is proposed for Energy Dispersive X-ray fluorescence (EDXRF) spectra. The proposed method has two steps of background modeling and background correction. It is based on the basic concept which differentiates background areas from the peak areas in a spectrum and the SNIP algorithm, one of the popular methods for background removal, is used to enhance the performance. After detecting some points which belong to the background from a spectrum, its background is modeled by a curve fitting method based on them. And then the obtained background model is subtracted from the raw spectrum. The method has been shown to give better results than some of traditional methods, while working under relatively weak constraints or prior information.

• Solar Energy
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• v.12 no.3
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• pp.47-59
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• 1992

In the concentric tube type recuperator, which is the most typical type of radiation recuperator, installed on the exhaust-secion of industrial furnace, air flows between the adiabatic outer tube and the inner tube in which exhausted gas flows with high temperature. The waste heat of the exhausted gas is transferred to the inner tube, and transferred from the inner tube to the flowing air. The heat transfer by radiation In the concentric tube type recuperator is modeled using spherical harmonics approximation, namely, P-N method and numerically analyzed considering the effect of dynamic flow field. The results are compared with the existing empirical data. In addition, a theoretical method is presented for the analysis of the heat transfer characteristics of a recuperator with a reradiator installed in the inner tube, which causes re-radiant in the inner tube, and the characteristics of the recuperator is analyszed and defined.

• Proceedings of the Korea Water Resources Association Conference
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• 1980.08a
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• pp.44-46
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• 1980

파의 에너지 감쇠기구의 관점에서 볼 때 분류손실방식인 유공벽식 방파제 중에서 원형공이 벽 전체에 균일하게 분포되어 있고 구멍 직경에 비해 벽 두께가 얇은 삼중 유공벽형 Caisson의 각 벽에 작용하는 파력에 고나해 이론적 접근과 실험을 통한 실증을 시도해 보았다. 이론적인 방법으로는 토굴구효남의 이론을 응용하였으며 주어진 파랑조건에 대해 각 유공벽 전 후면에 연속방정식과 Bernoulli 방정식을 이용하여, 각 영역별 연속 Potential의 진폭과 위상각에 대한 비선형 12원 연립방정식을 만들었고 Computer를 이용하여 반복법으로 각 속도 Potential을 확정하였다. 이렇게 구한 속도 Potential을 압력방정식에 대입하여 각 벽별 파력을 계산하였으며 동일한 파랑조건하의 실험에서 각 벽별 파력을 측정하여 양자를 서로 비교검토하였다. Bernoulli의 방정식중 에너지 손실항은 의사비선형으로 처리하였다. 유공율조합 0.25-0.3-0.2이고, 판두께가 1cm인 모형의 실험결과, 각 벽별 최대파력치의 특성으로서는 첫때, S-2, S-3등 간벽에 작용하는 파력이 전벽 및 후벽에 비해 두드러지게 작다는 사실과, 둘째 작용파력의 크기 순이 파형경사가 작을 때는 대략 S-4, S-1, S-2, S-3순이고 파형경사가 클 때에는 대략 S-1, S-4, S-2, S-3순이라는 점 등을 들 수 있겠다. 굴구효남이 가정한 f의 치 1.5를 사용하여 계산한 각 벽별 최대파력을 실험치와 비교해 본 결과, 파가 각 유공벽을 통과할 때의 손실수두를 실험에서의 양만큼 fr=1.5를 가정한 수학적 model이 설명해 주지 못한다고 볼 수 있으므로 두가지 방법에 의하여 본 실험에서 사용한 유공판의 손실계수를 근사적으로 추정하여 보았다. 추정한 f를 사용하여 다시금 각 벽별 최대파력을 계산하고 실험치와 비교해 보면 훨씬 서로 근접함을 알 수 있었다. 결국 본 논문의 이론을 사용하면 유공Caisson문제의 전체적인 윤곽 및 각 변수들의 파력에 대한 영향을 파악할 수 있겠다.

• Journal of Advanced Navigation Technology
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• v.21 no.4
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• pp.377-385
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• 2017

The solar cell need the characteristic interpreting because the solar cell changes greatly according to the isolation, temperature and load in the photovoltaic development. Moreover, to get many energy in photovoltaic development need the position tracking of the sun according to the environment change. Also, The solar cells should be operated at the maximum power point. In this paper, I used microprocessor and sensor and designed to improve the efficiency of the photovoltaic system the photovoltaic position tracker device, and compared the normal photovoltaic system of fixed form with the photovoltaic system of solar position tracked form. Moreover, compared the catalogue of solar cell module and the simulation through a mathematics modelling with the solar cell's characteristic interpreting and composed an power conversion system with boost converter and voltage source inverter. Used the constant voltage control method for maximum power point tracking in boost converter control and, used the SPWM(Sinusoidal Pulse Width Modulation) control method in inverter control. The result was less then 5% when compared the catalogue of solar cell module and the simulation through a mathematics modelling. The boost rate of boost converter was similar to 167 % with the simulation.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.4
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• pp.683-688
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• 2018

Recently, the demand for electric energy has been increasing due to the spread of hybrid electric vehicles. In this study, to meet this demand, the ANSYS MAXWELL electromagnetic simulation system was used to compare the power generation characteristics of three types of suspension system that can generate electricity using energy harvesting technology. Next, the optimal design was determined for each model by using the commercial PIDO (Process Integration and Design Optimization) tool, PIANO (Process Integration, Automation and Optimization). We selected three design variables and constructed an approximate model based on the experimental design method through electromagnetic analysis for 18 experimental points derived from Orthogonal Arrays among the experimental design methods. Then, we determined the optimal design by applying the Evolutionary Algorithm. Finally, the optimal design results were verified by electromagnetic simulation of the optimum design result model using the same analysis conditions as those of the initial model. After comparing the power generation characteristics for the optimal structure for each linear generator model, the maximum power generation amounts in the 8pole-8slot, 12pole-12slot, and 16pole-16slot structures were 366.5W, 466.7W and 579.7W, respectively, and it was found that as the number of slots and poles increases, the power generation increases.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.15 no.4
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• pp.675-691
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• 2002

The focus of this work is on the development of large-scale numerical optimization methods for optimal control of steady incompressible Navier-Stokes flows. The control is affected by the suction or injection of fluid on portions of the boundary, and the objective function of fluid on portions of the boundary, and the objective function represents the rate at which energy is dissipated in the fluid. We develop reduced Hessian sequential quadratic programming. Both quasi-Newton and Newton variants are developed and compared to the approach of eliminating the flow equations and variables, which is effectively the generalized reduced gradient method. Optimal control problems we solved for two-dimensional flow around a cylinder. The examples demonstrate at least an order-of-magnitude reduction in time taken, allowing the optimal solution of flow control problems in as little as half an hour on a desktop workstation.