• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.11
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• pp.1110-1118
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• 2009

This paper presents an optimal design of magnetorheological(MR) damper based on analytical methodology and finite element analysis. The proposed MR damper consists of MR valve and gas chamber. The MR valve is constrained in a specific volume and the optimization problem identifies geometric dimensions of the valve structure that maximize the pressure drop of the MR valve or damping force of the MR damper. In this work, the single-coil annular MR valve structure is considered. After describing the schematic configuration and operating principle of MR valve and damper, a quasi-static model is derived based on Bingham model of MR fluid. The magnetic circuit of the valve and damper is then analyzed by applying the Kirchoff' s law and magnetic flux conservation rule. Based on the quasi-static modeling and the magnetic circuit analysis, the optimization problem of the MR valve and damper is built. The optimal solution of the optimization problem of the MR valve structure constrained in a specific volume is then obtained and compared with the solution obtained from finite element method.

• Journal of the Korea Safety Management & Science
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• v.6 no.4
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• pp.155-170
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• 2004

Among the semiconductor If-chips, unlike memory chips, a majority of Application Specific IC(ASIC) products are produced by customer orders, and meeting the customer specified due date is a critical issue for the case. However, to the one who understands the nature of semiconductor manufacturing, it does not take much effort to realize the difficulty of meeting the given specific production due dates. Due to its multi-layered feature of products, to be completed, a semiconductor product(called device) enters into the fabrication manufacturing process(FAB) repeatedly as many times as the number of the product specified layers, and fabrication processes of individual layers are composed with similar but not identical unit processes. The unit process called photo-lithography is the only process where every layer must pass through. This re-entrant feature of FAB makes predicting and planning of due date of an ordered batch of devices difficult. Parallel machines problem in the photo process, which is bottleneck process, is solved with restricted roll out algorithm. Roll out algorithm is a method of solving the problem by embedding it within a dynamic programming framework. Restricted roll out algorithm Is roll out algorithm that restricted alternative states to decrease the solving time and improve the result. Results of simulation test in condition as same as real FAB facilities show the effectiveness of the developed algorithm.

• Journal of Korean Port Research
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• v.13 no.2
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• pp.189-198
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• 1999

The purpose of this paper is to develop a knowledge-based real-time decision support system to support decision makers for efficient berth operation of Inchon Port. In these days the berth operation problems have been many studied. The berth operation rules differ from port to port and the problem is highly dependent on natural geographical and operational environment of port. In Inchon Port the ship’s entrance into port and departure from port is extremely affected status of dock. In this paper we analyzed some effects of dock a specific character of Inchon Port with a real data of ship’s in Inchon Port. And reconstruct a previous expert’s knowledge of berth allocating problem in Inchon Port. Also the mechanism for the efficient berth operation has been studied by repeatedly dispatching in order to obtain a best effect of berth allocation, with real-time updated information for delay at service time of a specific berth and changing of a working-berth. The system is developed with graphic user interface(GUI) concept using user interactive approach. And this system will be provide decision support maker with an efficient and fast way to berth allocating and reduce wastes of time space and manpower in Inchon Port operation.

• Korean Journal of Computational Design and Engineering
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• v.14 no.5
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• pp.297-305
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• 2009

Automatic generation of the mid-surfaces of a CAD model is becoming a useful function in that it can help increase the efficiency of engineering analysis as far as it does not affect the result seriously. Several methods had been proposed previously to automatically generate the mid-surfaces, but they often failed to generate the mid-surfaces of complex CAD models. Due to the inherent difficulty of this mid-surface generation problem, it may not be possible to come up with a complete and general method to solve this problem. Since a method that can handle a specific case may not work for different cases, it seems that developing case-specific methods ends up with solving only a fraction of the problem. In this paper, therefore, we propose a method to generate mid-surfaces based on a divide-and-conquer paradigm. This method first decomposes a complex CAD model into simple volumes. The mid-surfaces of the simple volumes are automatically generated by the existing methods, and then they are converted into the mid-surfaces of the original CAD model.

• International Journal of Industrial Entomology and Biomaterials
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• v.38 no.2
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• pp.31-37
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• 2019

Silkworm larval mortality specifically during spinning stage leading to non-spinning with specific morphological symptoms was frequently complained by sericulturists in Karnataka, India during 2015. Survey was conducted and information collected through questionnaire from the identified farmers who faced the problem of non-spinning in both traditional and non-traditional areas of Karnataka. Survey results indicate that the problem is specific to the silkworm crop of those farmers' who shifted from other crops of agriculture/ horticulture/olericulture/ floriculture to Sericulture. Silkworm rearing performance of the batches fed with these leaves confirmed that the pesticide sprayed to the crops previous to mulberry, remain in the soil and when mulberry plantation is taken up in these gardens, the pesticide is absorbed by the roots of mulberry plants and transported to the leaves. Silkworms that feed on these mulberry leaves, grow and ripen normally but during spinning stage, larvae die with external symptoms like regurgitation, body shrinkage, rectal protrusion later become hook shaped leading to non-spinning or partial metamorphosis into pupa and death or spin flimsy cocoons. Larval mortality ranged from a minimum of twenty five percent to a maximum of hundred percent. The problem was noticed from the first harvest of leaves and lasted for a maximum period of 36 months. Cocoon crop loss depends on the concentration, duration and type of pesticides used previously for other crops.

• Proceedings of the Korean Operations and Management Science Society Conference
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• 2004.05a
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• pp.425-428
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• 2004

Flexible assembly line (FAL) is a production system that assembles various parts in unidirectional flow line with many constraints and manufacturing flexibilities. In this research we deal with a FAL balancing problem with the objective of minimizing the maximum workload allocated to the stations. However, almost all the existing researches do not appropriately consider various constraints due to the problem complexity. Therefore, this thesis addresses a balancing problem of FAL with many constraints and manufacturing flexibilities, unlike the previous researches. To solve this problem we use a genetic algorithm (GA). To apply GA to FAL, we suggest a genetic representation suitable for FAL balancing and devise evaluation method for individual's fitness and genetic operators specific to the problem, including efficient repair method for preserving solution feasibility. The experimental results are reported.

• Industrial Engineering and Management Systems
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• v.12 no.1
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• pp.9-15
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• 2013

An inverse minimum spanning tree problem makes the least modification on the edge weights such that a predetermined spanning tree is a minimum spanning tree with respect to the new edge weights. In this paper, the concept of uncertain ${\alpha}$-minimum spanning tree is initiated for minimum spanning tree problem with uncertain edge weights. Using different decision criteria, two uncertain programming models are presented to formulate a specific inverse minimum spanning tree problem with uncertain edge weights involving a sum-type model and a minimax-type model. By means of the operational law of independent uncertain variables, the two uncertain programming models are transformed to their equivalent deterministic models which can be solved by classic optimization methods. Finally, some numerical examples on a traffic network reconstruction problem are put forward to illustrate the effectiveness of the proposed models.

• Korean Management Science Review
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• v.20 no.2
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• pp.81-93
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• 2003

These days we come across many wicked problems whose solutions are beyond individuals intellectual ability. These problems can be resolved through collaborative group interaction. We developed an internet-based asynchronous group interaction support system, after looking into the collaborative problem solving process and the IBIS (Issue-Based Information System) argumentation model. It has the following characteristics ; 1) it is developed based on the modified IBIS model which is a model for group interaction to resolve wicked problems ; 2) it supports both processes of seeking and comparing solutions, while most similar systems do not have a feature to support the latter process ; 3) different structures can be defined dynamically according to the purpose of group interaction, so that it could be used for collaborative problem solving in a specific domain. To show the usability of the system, we carried out an experiment, whose result is shown at the end.

• Journal of Communications and Networks
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• v.11 no.5
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• pp.489-499
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• 2009

We describe the fundamental issue of scheduling the allocation of wireless network resources and provide several formulations of the associated problems. The emphasis is on scheduling transmission attempts. We place this problem in the context of existing approaches, like information theoretic and traditional network theoretic ones, as well as novel avenues that open up the possibility of addressing this issue for non-stationary and non-ergodic environments. We summarize concrete recent results for specific special cases that include unicast and multicast traffic, different objective functions, and reduced complexity versions of the problem. We conclude with some thoughts for future work. We identify and single out the cross-layer nature of the problem and include a simple physical-layer criterion in what is mostly a medium access control (MAC) problem.

• International Journal of Advanced Culture Technology
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• v.7 no.4
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• pp.222-228
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• 2019

In recent years, in order to enhance the problem-solving skills required by the industrial field, universities have introduced the Problem-Based Learning(PBL) method to solve the problems caused by the lack of creativity, problem solving ability and self-directed learning. This study applied PBL class methods such as 'learning based on individual specific problems', 'self-directed learning', and 'small-group learning of small members' to practical design of fashion design. To do this, I conducted a questionnaire after conducting research based on the PBL module for one semester in a practical class of fashion design major at P University. As a result of the survey, the satisfaction and achievement of the class conducted by PBL learning method was improved than the existing teaching method. As such, if PBL class is used as a way of solving problems through close communication between professors and learners, it is expected to be established as a learner-centered education method that can improve creativity and professionalism.