• 한국경영과학회지
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• 제19권1호
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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.

• 한국경영과학회:학술대회논문집
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• 대한산업공학회/한국경영과학회 1996년도 춘계공동학술대회논문집; 공군사관학교, 청주; 26-27 Apr. 1996
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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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• 제19권2호
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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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• 제19권6호
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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.

• 한국경영과학회지
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• 제4권2호
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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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• 제52권6호
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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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• 제3권3호
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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.

• 한국지하수토양환경학회지:지하수토양환경
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• 제18권1호
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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.

• 대한교통학회지
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• 제17권5호
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• pp.111-122
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• 1999

소화물 일관 운송 과정에서 발생하는 직접비용을 최소화하는 수리 모형과 해법이 제안되었다. 고려되는 비용으로는 화물 운송을 위한 차량 운행에 필요한 제반 비용인 링크 비용과 터미널에서 일어나는 하차, 분류, 재적 재등 하역 작업에서 발생하는 노드 비용을 감안하였고 총비용을 줄이기 위한 화물의 운송 경로가 모형의 결정변수이다. 해법으로는 최종해의 품질은 다소 미흡하나 계산 시간이 짧은 Steepest Descent Method와 최종해의 품질이 우수하나 계산 시간이 많이 소요되는 Simulated Annealing Method를 활용한 두개의 알고리즘이 고안되었다. 최적해를 찾아가기 위한 탐색의 출발점이 되는 초기해는 Dijkstra의 최단경로 알고리즘을 수정하여 찾는다. 예제를 통하여 알고리즘의 계산 과정을 설명하였고 제시된 두 방법의 최종해는 초기해에 비하여 비용 측면에서 각각 12%. 15%의 절감 효과가 있음을, 적재율 측면에서 초기해의 62.6%에서 각각 774%. 87.4% 향상됨을 확인하였다.

• 한국경영과학회:학술대회논문집
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• 한국경영과학회 2008년도 추계학술대회 및 정기총회
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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.