• Journal of the Korean Society for Precision Engineering
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• v.13 no.7
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• pp.66-77
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• 1996

Optimal topology design is to search the optimal configuration of a structure which can be used as a shape at the conceptual design stage. Our objective is to maximize the stiffness of the structures and ribs under a material usage constraintl. The density of each finite element is the design variable and its relationship with Young's modulus is expressed by quadratic form. The configuration is represented by the entire density distribution, the structural analysis is performed by finite element method and the optimiza- tion is performed by Feasible Direction Method. Feasible Direction Method can handle various problems simultaneously, that is, mult-objectives and multi-constraints. Total computation time can be reduced by the quadratic relationship between the density and the material property and fewer design variables than Homogenization Method. Toplogy optimization technique developed in this research is applied to design the shapes of the ribs.

• Journal of Environmental Health Sciences
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• v.40 no.1
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• pp.63-70
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• 2014

Objective: The purpose of this study was to investigate the occurrence of indicator organisms in essential sanitary ware in public restrooms. Methods: Twelve public restrooms were randomly selected. Samples at three locations (toilet seat, toilet flush handle/lever, and faucet handle) in the restrooms were collected with moistened-sterile cotton swabs and applied to media in order to determine aerobic colony count (ACC), total coliforms, and Escherichia coli. Results: Most of the samples taken in summer showed a higher level of ACC than those taken in winter (p<0.05). Female restrooms showed higher ACC levels on faucet handles and male restrooms on toilet flush handles/levers (p<0.05). Overall, faucet handles contained the greatest level of ACC, followed by toilet seats, whereas the least load was found on toilet flush handles/levers. The ACC level of samples in the restrooms in public parks, subway stations, and educational institutions varied. Total coliforms were identified in about 20% of toilet seats and faucet handles in male restrooms and faucet handles in female restrooms in summer. These locations were also the sites of positive results of E. coli isolation. Conclusions: The public restrooms were significantly more contaminated in summer than in winter. Overall, the most contaminated locations in the restrooms were toilet seats in male restrooms, and faucet handles in female restrooms. Poor hygienic status was indicated by the positive results of total coliforms and E. coli on samples from some sites. Therefore, sanitary control of restrooms should be improved. These results should be confirmed in a larger study that includes more public restrooms.

• Journal of Digital Convergence
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• v.17 no.1
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• pp.301-311
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• 2019

Digital convergence put a huge challenges for broadcast media in terms of integrating user generated content (UGC). Keeping this in mind, objective of the study is to explore the factors that affecting UGC's integration in Broadcast channel from developing countries' perspective. We explored how and why UGC are appearing in Bangladeshi Television news. In-depth interview was used and news editorial level staffs were selected from leading Bangladeshi television channels. Findings suggest that, state interventions in crisis events and lack of experiences to handle crisis reporting played a crucial role to incorporate UGC in television news bulletins. One of the significant findings is that, mere traditional guidelines and work policy of the media houses will not be enough to handle user generated content as well as citizen's participation in news media. Thus, we recommend to formulate a comprehensive user generated content integration policy in the context of Bangladesh.

• International conference on construction engineering and project management
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• 2007.03a
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• pp.642-652
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• 2007

Many contracting firms and project managers in the construction industry have started to utilize multi objective optimization methods to handle multiple conflicting goals for completing the project within the stipulated time and budget with required quality and safety. These optimization methods have increased the pressure on decision makers to search for an optimal resources utilization plan that optimizes simultaneously the total project cost, completion time, and crashing cost by considering indirect cost, contractual penalty cost etc., practically charging them in terms of direct cost of the project which is fuzzy in nature. This paper presents a multiple fuzzy goal programming model (MFGP) that supports decision makers in performing the challenging task. The model incorporates the fuzziness which stems from the imprecise aspiration levels attained by the decision maker to these objectives that are quantified through fuzzy linear membership function. The membership values of these objectives are then maximized which forms the fuzzy decision. The problem is solved using LINGO 8 optimization solver and the best compromise solution is identified. Comparison between solutions of MFGP, fuzzy multi objective linear programming (FMOLP) and multiple goal programming (MGP) are also presented. Additionally, an interactive decision making process is developed to enable the decision maker to interact with the system in modifying the fuzzy data and model parameters until a satisfactory solution is obtained. A case study is considered to demonstrate the feasibility of the proposed model for optimization of project network parameters in the construction industry.

• Journal of Korean Society for Geospatial Information Science
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• v.4 no.2 s.8
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• pp.55-61
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• 1996

The objective of this paper is to show an optimal design model for branched water supply system which also can find the optimal location of pumping stations using linear programming. GIS is utilized in this model to better handle the data and the results front the optimization. The developed model considers hydraulic influences of some appurtenances such as supply tunnels and a filtration plant The model also considers tunnel construction cost which should be treated differently from pipe construction cost Different from other models presently available, the model guarantees a nonnegative pressure at every junction node in the system. The objective function includes annual operation cost (electricity rate) ill addition to initial construction cost, thus producing a more reasonable decision. The model selects the optimal diameter not in the form of continuous number but in the form of commercial discrete diameter (pipe size) using the pipe lengths as decision variables instead of pipe diameters. The model not only determines the optimal pumping head for each pumping station but also finds the optimal location and number of pumping stations. GIS is used to handle hydraulic and budgetary data automatically and to visualize the results for the of optimal design of the system. The model has been applied to an existing water supply system. 'The results show that the optimization model with the aid of GIS is helpful in the decision-nulling process for the design of more economical systems, and can be dot into practice successfully.

• Journal of KIISE:Software and Applications
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• v.31 no.6
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• pp.829-839
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• 2004

Methods based on integer programming have been shown to be very effective in solving various crew pairing optimization problems. However, their applicability is limited to problems with linear constraints and objective functions. Also, those methods often require an unacceptable amount of time and/or memory resources given problems of larger scale. Heuristic methods such as neighborhood search, on the other hand, can handle large-scaled problems without too much difficulty and can be applied to problems having any form of objective functions and constraints. However, neighborhood search often gets stuck at local optima when faced with complex search spaces. This paper presents ,i hybrid algorithm of neighborhood search and integer programming, which nicely combines the advantages of both methods. The hybrid algorithm has been successfully tested on a large-scaled crew pairing optimization problem for a real subway line.

• Journal of the Korea Convergence Society
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• v.8 no.10
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• pp.19-28
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• 2017

Recently the cargo transportation is increasing according to lager containerships in the container terminal. Thus, the various ways(such as efficient vehicle scheduling and minimizing delay time) are applied to increase productivity to handle the increasing cargo transportation in the container terminal. In this paper, the optimized model(Solvers) is applied to improve the existing heuristic method as a way of increasing productivity. The experimental design is that the result of two objective functions(minimizing travel and delay time of the empty vehicle) is compared to the result of the existing heuristic method by six sample problems. As a result of the two objective function experiments, the optimized model draws 5.3% more improved performance than the heuristic method in four of six problem samples.

• The Journal of Society for e-Business Studies
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• v.18 no.1
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• pp.165-189
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• 2013

Conceptual modeling is a critical activity for developing successful business information systems. The objective of this study is to evaluate the possibility of applying the constant comparison method from the grounded theory to conceptual modeling. To achieve the objective, we trained novice modelers and split them into two groups for evaluation. The experimental results show that applying the constant comparison method could increase acceptability from more experienced conceptual modelers. Moreover, while the control group was experienced difficulties when domain knowledge is unfamiliar, the experimental group could handle difficulties more effectively. In addition, applying the constant comparison method also decreased the time to complete analysis for conceptual modeling.

• Journal of the Society of Naval Architects of Korea
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• v.45 no.2
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• pp.192-201
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• 2008

The design process becomes more difficult due to the increasing complexity of products. Thus, without any proper design experience, designer cannot handle his design problems systematically. Besides, the conventional optimal design method cannot be used effectively at the early design stage, since most design problems must be formulated in terms of objective and constraint functions based on the mathematical concepts of Operation Research. Thus, in this paper, new design concept based on FBS (Function-Behavior-Structure) design model is introduced to help the novice designer formulate the complex design problems systematically into a mathematical form. In this FBS model, function means the designer's new intents designer wants to create for, structure stand for a final product configuration and behaviour is a product's performance. FBS design model is thus rather totally different concept used for formulating design problem, compared with conventional optimal design method. To validate this new FBS model, 330K VLCC design case is performed, and we found, though it is one design example case, that this new design concept could be effectively used for future ship design problems since, during the formulating design problem, the only engineering terminology such as function, structure, and behaviour of design product is used based on the engineering concepts, instead of mathematical terminology such as objective and constraints.

• Journal of Ship and Ocean Technology
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• v.5 no.2
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• pp.14-26
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• 2001

This paper presents a novel design approach that could generate structural design alternatives having different topologies and then, select the optimum structure from them with simulataneously determining its optimum design variables related to geometry and the member size subjected to the multiple objective design environments. For this purpose, a specialized genetic algorithm, called StrGA_DeAl + MOGA, which can handle the design alternatives and multi-criteria problems very effectively, is developed for the optimal structural design. To validate the developed method, method, plain truss design problems are considered as illustrative example. To begin with, some possible topological of the truss structure are suggested based on the stability criterion that should be satisfied under the given loading condition. Then, with the consideration of the given multi-criteria, several different topology forms are selected as design alternatives for the second step of the conceptual design process. Based on the chosen topolgy of truss structures, the sizing or shaping optimization process starts to determine the optimum design parameters. Ten-bar truss problems are given in the paper to confirm the above concept and methodology.