• Journal of the Korean Operations Research and Management Science Society
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• v.19 no.1
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• pp.113-122
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• 1994

This study proposes a new procedure to find an initial solution to reduce the number of iterations of goal programming. The process of computing an initial solution is divided into two steps in this study. Decision variables which satisfy feasibility using Gaussian eliminations construct an initial solution reducing the iterations in the first step. It uses LHS as a tool that decision variables construct an initial solution. The initial solution which is constructed by the first step computes the updated coefficient of the objective function in the second step. If the solution does not satisfy the optimality, the optimal solution using the Modified Simplex Method is sought. The developed method doesn't reduce the overall computing time of goal programming problems, because time is more required for the process of constructing an initial solution. But The result of this study shows that the proposed procedure can reduce the large number of iterations in the first step effectively.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 1996.04a
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• pp.530-533
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• 1996

This paper deals with finding an initial solution and modifying search direction by the centrering force in the predictor-corrector method which is a variant of the primal-dual barrier method. These methods were tested with NETLIB problems. Initial solutions which are located close to the center of the feasible set lower the number of iterations, as they enlarge the step length. Three heuristic methods to find such initial solution are suggested. The new methods reduce the average number of iterations by 52% to at most, compared with the old method assigning 1 to initial valurs. Solutions can move closer to the central path fast by enlarging the centering force in early steps. It enlarge the step length, so reduces the number of iterations. The more effective this method is the closer the initial solution is to the boundary of the feasible set.

• Geomechanics and Engineering
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• v.19 no.2
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• pp.141-151
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• 2019

A novel theoretical solution is presented for created (zero initial radius) cavity expansion problem based on CamClay model and considers the effect of initial anisotropic in-situ stress and drained conditions. Here the strain of this theoretical solution is small deformation in elastic region and large deformation in plastic region. The works for cylindrical and spherical cavities expanding in drained condition from zero initial radius are investigated. Most of the conventional solutions were based on the isotropic and undrained condition, however, the initial stress state of natural soil mass is anisotropy by soil deposition history, and drained cavity expansion calculation is closer to actual engineering in permeable soil mass. Finally, the parametric study is presented in order to the engineering significance of this work.

• Geomechanics and Engineering
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• v.19 no.6
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• pp.513-522
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• 2019

This study presents an elasto-plastic (EP) solution for drained cavity expansion on the basis of unified strength failure criterion and considers the influence of initial stress state. Because of the influence of initial consolidation of soil mass, the initial stress may be anisotropic in the natural soil mass. In addition, the undrained hypothesis is usually used in the calculation of cavity expansion problem, but most of the cases are in the drained situation in practical engineering. Eventually, the published solution and the presented solution are compared to verify the suitability of the study.

• Journal of the Korean Operations Research and Management Science Society
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• v.4 no.2
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• pp.41-43
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• 1979

In transportation problems, various initial solution methods are known and being used. The purpose of this paper is to compare effectiveness of those methods in terms of time required in computing an initial solution. In this paper, Northwest Corner rule, Least Cost rule, Vogel's Approximation rule, Russel's Approximation rule, are compared, These rules are similar in loxio sized problems. But as the size of the problem become bigger, Russet's and Vogel's methods are found much more effective than others.

• Korean Chemical Engineering Research
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• v.52 no.6
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• pp.775-780
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• 2014

Micellar enhanced ultrafiltration (MEUF) was used to remove cadmium from an aqueous solution using sodium dodecyl sulfate (SDS) as a surfactant. Operational parameters such as initial permeate flux, retentate pressure, initial cadmium concentration, pH solution, molecular weight cut-off (MWCO), and molar ratio of cadmium to SDS were investigated. Removal efficiency of cadmium from an aqueous solution increased with an increase of retentate pressure, pH solution and molar ratio of cadmium to SDS, and decreased with an increase of initial permeate flux. Higher removal efficiency of cadmium from the aqueous solution was achieved using lower MWCO (smaller membrane pore size). Under optimized experimental condition, cadmium removal efficiency reached 74.6 % within an hour. Using MEUF-ACF hybrid process the removal efficiency of both cadmium and SDS was found to be over 90%.

• Journal of Positioning, Navigation, and Timing
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• v.3 no.3
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• pp.117-122
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• 2014

In CDGPS, ambiguity resolution is determined by the performance of a floating solution, and thus, the performance needs to be improved. In the case of precise positioning at a stationary position, the batch method using multiple measurements is used for the accuracy improvement of a position. The position accuracy performance of a floating solution is outstanding, but it has a problem of high computation cost because all measurements are used. In this study, to improve the floating solution performance of the initial static user in CDGPS, a floating solution method using a recursive filter was implemented. A recursive filter estimates the position solution of the current epoch using the position solution of up to the previous epoch and the pseudorange measurement of the current epoch. The computation cost of the floating solution method using a recursive filter was found to be similar to that of the epoch-by-epoch method. Also, based on actual GPS signals, the floating solution performance was found to be similar to that of the batch method. The floating solution using a recursive filter could significantly improve the performance of the prompt initial position and ambiguity resolution of the initial static user.

• Journal of Soil and Groundwater Environment
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• v.18 no.1
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• pp.46-56
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• 2013

Laboratory scale experiments to remove benzene in solution by using the bio-carrier composed of dead biomass have been performed. The immobilized bio-carrier with dead Bacillus drentensis sp. and polysulfone was manufactured as the biosorbent. Batch sorption experiments were performed with bio-carriers having various quantities of biomass and then, their removal efficiencies and uptake capacities were calculated. From results of batch experiments, 98.0% of the initial benzene (1 mg/L) in 1 liter of solution was removed by using 40 g of immobilized bio-carrier containing 5% biomass within 1 hour and the biosorption reaction reached in equilibrium within 2 hours. Benzene removal efficiency slightly increased (99.0 to $99.4%{\pm}0.05$) as the temperature increased from 15 to $35^{\circ}C$, suggesting that the temperature rarely affects on the removal efficiency of the bio-carrier. The removal efficiency changed under the different initial benzene concentration in solution and benzene removal efficiency of the bio-carrier increased with the increase of the initial benzene concentration (0.001 to 10 mg/L). More than 99.0% of benzene was removed from solution when the initial benzene concentration ranged from 1 to 10 mg/L. From results of fitting process for batch experimental data to Langmuir and Freundlich isotherms, the removal isotherms of benzene were more well fitted to Freundlich model ($r^2$=0.9242) rather than Langmuir model ($r^2$=0.7453). From the column experiment, the benzene removal efficiency maintained over 99.0% until 420 pore volumes of benzene solution (initial benzene concentration: 1 mg/L) were injected in the column packed with bio-carriers, investigating that the immobilized carrier containing Bacillus drentensis sp. and polysulfone is the outstanding biosorbent to remove benzene in solution.

• Journal of Korean Society of Transportation
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• v.17 no.5
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• pp.111-122
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• 1999

A service network design model for LTL freight transportation is formulated as a mixed integer Programming Problem with two heuristic solution a1gorithms. The Proposed model derives the transportation Path for each origination-destination pair, taking into account transportation cost over the links and handling costs over the nodes. The first algorithm searches for a local minimum solution from a given initial solution by improving the quality of solution repeatedly while the second a1gorithm searches for a better solution using Simulated Annealing Method. For both solution algorithms, the initial solution is derived by a modified reverse Diikstras shortest Path a1gorithm. An illustrative example, Presented in the last part of the Paper, shows that the proposed algorithms find solutions which reduce the cost by 12% and 15% respectively, compared to the initial solution.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2008.10a
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• pp.236-246
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• 2008

We consider the Inventory Routing problem(IRP) for the vending machine operating system. An artificial immune system(AIS) is introduced to solve the IRP. The IPR is an rolling wave planning. The previous solution of IRP is one of good initial solution of current IRP. We introduce an Artificial Immune system with memory cell (AISM) which store previous solution in memory cell and use an initial solution for current problem. Experiment results shows that AISM reduced calculations time in relatively less demand uncertainty.