• 대한조선학회논문집
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• 제41권4호
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• pp.38-44
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• 2004

The motion response analysis of a submerged elliptic cylinder in waves is presented and the elliptic cylinder is a simplification of the section of submarine in this paper. The method is based on boundary integral method and two-dimensional 3 degree motions are calculated in regular harmonic waves. The fully nonlinear free surface boundary condition is assumed in an numerical domain and this solution is matched along an assumed boundary as a linear solution composed of transient Green function, The large amplitude motions of an elliptic cylinder are directly simulated and effects of wave frequency, wave amplitude and the distance from buoyancy center to gravity center are discussed.

• 한국해양공학회지
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• 제14권1호
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• pp.60-66
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• 2000

In order to study for corrosion behavior of reinforcing steel with oxidation layer. Experiments were done with various NaCl concentrations and with immersion time in simulated concrete pore solution(SPS) the characteristics of corrosion behavior were measured by polarization resistance method and cyclic potentiodynamic method. reinforcements were coated by epoxy except corrosion without oxidation layer and it also showed two anodic-nose. by the result of potention dynamic test the potential curve shift to low with time and anodic-nose was appeared with 3% NaCl solution after 15 days. By result of cyclic Potentiodynamic test the type of corrosion was different accoding to concentration.

• Industrial Engineering and Management Systems
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• 제8권1호
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• pp.29-36
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• 2009

We present two local-search based metaheuristics for the multi-source capacitated facility location problem. In such a problem, each customer's demand can be supplied by one or more facilities. The problem is NP-hard and the number of locations in the optimal solution is unknown. To keep the search process effective, the proposed methods adopt the following features: (1) a multi-exchange neighborhood structure, (2) a tabu list that keeps track of recently visited solutions, and (3) a multi-start to enhance the diversified search paths. The transportation simplex method is applied in an efficient manner to obtain the optimal solutions to neighbors of the current solution under the algorithm framework. Two in-and-out selection rules are also proposed in the algorithms with the purpose of finding promising solutions in a short computational time. Our computational results for some of the benchmark instances, as well as some instances generated using a method in the literature, have demonstrated the effectiveness of this approach.

• 산업경영시스템학회지
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• 제30권1호
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• pp.82-88
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• 2007

This paper considers a topological optimization of a computer network design with a cost constraint. The objective is to find the topological layout of links, at maximal reliability, under the constraint that the network cost is less or equal than a given level of budget. This problem is known to be NP-hard. To efficiently solve the problem, a genetic approach is proposed. Two illustrative examples are used to explain and test the proposed approach. Experimental results show evidence that the proposed approach performs more efficiently for finding a good solution or near optimal solution in comparison with a simulated annealing method.

• Journal of Mechanical Science and Technology
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• 제20권8호
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• pp.1217-1223
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• 2006

Induction heating is a process that is accompanied with magnetic and thermal situation. This paper presents a simulation of a magneto-thermal coupled problem of an induction heating process for moving inductor coil. In the magnetic and thermal analyses, temperature-dependent magnetic and thermal material properties were considered. As the inductor coil moves in the process, solution domains corresponding to inductor changes into those of the air, and the solution domains of air change into those of the inductor. For these reasons, modeling of induction heating process is very difficult with general purpose commercial programs. In this paper, induction heating process for moving coil was simulated with the concept of traveling the position of the heating planes. Finite element program was developed and finite element results were compared with the experimental results.

• Korean Journal of Hydrosciences
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• 제5권
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• pp.85-97
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• 1994

A hybrid finite difference method for the longitudinal dispersion equation, which is based on combining the Holly-Preissmann scheme with fifth-degree Hermite interpolating polynomial and the generalized Crank-Nicholson scheme, is described and comparatively evaluated with other characteristics-based numerical methods. Longitudinal dispersion of an instantaneously-loaded pollutant source is simulated, and computational results are compared with the exact solution. The present method is free from wiggles regardless of the Courant number, and exactly reproduces the location of the peak concentration. Overall accuracy of the computation increases for smaller value of the weighting factor, $\theta$of the model. Larger values of $\theta$ overestimates the peak concentration. Smaller Courant number yields better accuracy, in general, but the sensitivity is very low, especially when the value of $\theta$ is small. From comparisons with the hybrid method using cubic interpolating polynomial and with splitoperator methods, the present method shows the best performance in reproducing the exact solution as the advection becomes more dominant.

• 대한기계학회논문집B
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• 제28권7호
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• pp.871-878
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• 2004

An accurate adaptive mesh refinement based on the CIP method is proposed and it is applied to solve the two dimensional advection equations. In this method, the level set function is employed to refine and merge the computation cells. To enhance the accuracy of the solution, the spatial discretization is made by the CIP method. The CIP method has many advantages such as the third order accuracy, less diffusivity, and shape conserving. The mathematical formulation and numerical results are also described. To verify the efficiency, accuracy, and capability of the proposed algorithim, two dimensional rotating slotted cylinder and idealized frontogenesis are numerically simulated by the present scheme. As results, it is confirmed that the present method gives an efficient, reasonable solution in the advection equation.

• Bulletin of the Korean Chemical Society
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• 제8권5호
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• pp.384-388
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• 1987

Modified Bloch equations were used to simulate the solution EPR spectra of mixed-valence heteropolyanions containing vanadium(IV) and vanadium(V). Simulated are the 15-, 22-, 36- and 43-line spectra of $\alpha$-1,2-$[PV(IV)VW_{10})O_{40}]^{6-},\;[P_2V(IV)V_2W_{15}O_{62}]^{10-},\;[HP_2V(IV)V_2W_{15}O_{62}]^{9-}$ and $\alpha$-1,2,3-$[HSiV(IV)V_2W_9O_{40}]^{7-}$, respectively. The transition probabilities for the intramolecular electron transfer were determined from the simulations.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2021년도 가을 학술논문 발표대회
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• pp.65-66
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• 2021

In this study, the optimum amount of hybrid inhibitors i.e. L-Arginine (LA) and sodium phosphate tribasic dodecahydrate (SP), applied for carbon steel rebar in simulated pore concrete (SCP) solution contaminated with 3.5 wt.% NaCl, was discovered. The corrosion inhibition performance of hybrid inhibitors was investigated by open circuit potential (OCP), electrochemical impedance spectroscopy (EIS), and potentiodynamic polarization. The highest corrosion inhibition efficiency was found as 99.52% corresponding to 2% LA and 0.25% SP after 210 h exposure. Anodic type inhibition action was confirmed by potentiodynamic polarization study. Surface studies including scanning electron microscopy (SEM), and atomic force microscopy (AFM) were used to figure out the surface morphology of the steel rebar treated with hybrid inhibitors in order to collaborate with electrochemical studies.

• Korean Chemical Engineering Research
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• 제43권1호
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• pp.33-38
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• 2005

피콜리네이트 착화제가 들어있는 제염 폐액에서 바나듐 및 철 이온종의 평행분배 거동을 pH 값과 조성이 다른 여러 조건에서 모사하였다. 피콜리네이트 대 바나듐의 몰비를 일정한 값으로 고정하고 금속 이온의 농도를 변화시킬 경우 평행분배 곡선의 형태는 바나듐에 대한 피콜리네이트의 농도가 6배인 고농도 및 3배인 저농도 LOMI 제염 조건의 용액에서 모두 크게 바뀌지 않았다. 그러나 저농도 피콜리네이트 조건의 용액에서는 철(II)-피콜리네이트의 평행분배 곡선의 형태가 많이 변화하였는데, 이와 같은 현상은 용액에 들어있는 철에 대한 피콜리네이트의 상대적인 양이 부족하기 때문에 일어나며 바나듐(III) 및 철(II) 이온종이 피콜리네이트 착화물을 형성하는 안정도 상수(stability constant)의 차이에서 비롯된다. 본 연구에서 구한 평형분배 곡선은 이온교환 조작과 같은 LOMI 제염 폐액의 처리 과정에서 용액의 조건 변화에 따른 반응 현상을 예측하거나 이해하는데 매우 유용하게 활용될 수 있다.