• Journal of the Ergonomics Society of Korea
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• v.13 no.2
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• pp.65-79
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• 1994

A biomechanical model of lower extremity in seated postures was developed to assess muscular activities of lower extremity involved in a variety of foot pedal operations. The model incorporated four rigid body segments with the twenty-four muscles to represent lower extremity. This study deals with quasi-static movement to investigate dymanic movement effect in seated foot operation. It is found that optimization method which has been used for modeling the articulated body segments does not predict the forces generated from biarticular muscles and antagonistic muscles reasonably. So, the revised nonlinear optimization scheme was employed to consider the synergistic effects of biarticular muscles and the antagonistic muscle effects from the stabilization of the joint. For the model validation, three male subjects performen the experiments in which EMG activities of the nine lower extremity muscles were measured. Predicted muscle forces were compared with the corresponding EMG amplitudes and it showed no statistical difference. For the selection of optimal seated posture, a physiological meaningful criterion for muscular load sharing developed.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.51 no.3
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• pp.285-294
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• 2015

As a "kind of" mature ship form, planing hull has been widely used in military and civilian areas. Therefore, a reasonable design for planing hull becomes more and more important. For planing hull, resistance and trim are always the most important problems we are concerned with. It affects the planing hull's economic efficiency and maneuverability very seriously. Instead of the expensive towing tank experiments, the development of computer comprehensive ability allows us to previously apply computational fluid dynamics(CFD)to the ship design. In this paper, the CFD method and Goal Driven Optimization (GDO) were used in the estimations of planing hull resistance and running attitude to provide a possible method for performance computation of planing hull.

• International journal of advanced smart convergence
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• v.9 no.2
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• pp.157-163
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• 2020

Recently the blockchain technology has been actively studied due to its great potentiality. The smart contract is a key mechanism of the blockchain system. Due to the short history of the smart contract, many issues have not been solved yet. One main issue is vulnerability and another main issue is cost optimization. While the vulnerability of smart contract has been actively studied, the cost optimization has been rarely studied. In this paper, we propose two cost optimization methods for smart contracts running on the blockchain system. Triggering a function in a smart contract program code may require costs and it is repeated continuously. So the minimization of costs required to trigger a function of smart contract while maintaining the performance equally is very important. The proposed two methods minimize the usage of expensive permanent variables deployed on the blockchain system. We apply the proposed two methods to three prevalent blockchain platforms: Ethereum, Klaytn and Tron. Evaluation experiments verify that the proposed scheme significantly reduces the costs of functions in the smart contract written with Solidity.

• Journal of Ocean Engineering and Technology
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• v.19 no.3
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• pp.59-65
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• 2005

In today's industry, the butterfly valve has been used to control a flow effectively. However, it is difficult to have the existing structural optimization using field analysis from CFD to structure analysis when the structure is influenced by fluid. Therefore, an initial model of this study is to evaluate the stability of the valve using FEM and CFD. And, it selected variable using initial analysis results. Also, it accomplished the shape optimization design using the orthogonal arrangement and characteristic function. Research result, a few experiments showed the optimal results of there dimensional structures to be multi-objective.

• Proceedings of the IEEK Conference
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• 2007.07a
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• pp.225-226
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• 2007

In this paper, we present our study about the optimization of the block matching algorithm on a VLIW based DSP. The block matching algorithm is well known for its computational burden in motion picture encoding. As supposed to the previous researches where the optimization is achieved by optimizing SAD, the most heavy routine of the block matching, we optimize the block matching algorithm by applying software pipelining technique to the whole routine of the algorithm. Through experiments, the efficiency of the proposed optimization is verified.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.14 no.3
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• pp.65-73
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• 2015

This paper presents a method of predicting the machining parameters on the turning process of low carbon steel using a neural network with back propagation (BP) and particle swarm optimization (PSO). Cutting speed, feed rate, and depth of cut are used as input variables, while surface roughness and electric current consumption are used as output variables. The data from experiments are used to train the neural network that uses BP and PSO to update the weights in the neural network. After training, the neural network model is run using test data, and the results using BP and PSO are compared with each other.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.6 no.4
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• pp.44-49
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• 2007

In this paper, propose an optimal design to improve the mechanical efficiency of gate valve made by forging method. In order to design the experiments using table of orthogonal array and optimization design is conducted as application of real response model to Taguchi method based approximation model using computer simulation. Also, from verification of the response model with optimized results was confirmed that usefulness and reliance of application Taguchi method to structural optimum design using finite element analysis and equation.

• Journal of Korean Institute of Industrial Engineers
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• v.37 no.4
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• pp.408-414
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• 2011

The objective of this paper is to define local optimization algorithms (LOA) to solve Resource-Constrained Project Scheduling Problem (RCPSP) and analyze the performance of these algorithms. By representing solutions with activity list, three primitive LOAs, i.e. forward and backward improvement-based, exchange-based, and relocation-based LOAs are defined. Also, combined LOAs integrating two primitive LOAs are developed. From the experiments with standard test set J120 generated using ProGen, the FBI-based LOA demonstrates to be an efficient algorithm. Moreover, algorithms combined with FBI-based LOA and other LOA generate good solutions in general. Among the considered algorithms, the combined algorithm of FBI-based and exchangebased shows best performance in terms of solution quality and computation time.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.19 no.2
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• pp.178-183
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• 2010

Base-mounted type(BMT) driving assembly in CNC machine tools is an indispensable part to improve productivity by reducing tool changeover time and to meet the ever-increasing demand of precision machine tools. This study aimed to perform finite element analysis and geometric parameter optimization to improve the efficiency of BMT driving assembly. First, simulations for three-dimensional structural and vibration analysis were performed using ANSYS/Workbench on the initial geometric models of BMT driving assembly. After analyzing stress and deformation concentration zones, several new geometrical models were designed and evaluated by design of experiments and ANSYS/DesignXplorer. Through a series of analysis-evaluation-modification cycles, it was seen that designed models were effective in determining optimal geometry of BMT driving assembly.

• Asian Journal of Innovation and Policy
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• v.8 no.1
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• pp.122-140
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• 2019

Providing free primary care to everyone is an important goal pursued by many countries under universal health care programs. Countries like India need to efficiently utilize their limited capacities towards this purpose. Unfortunately, due to a variety of reasons, patients incur substantial travel and out-of-pocket expenses for getting primary care from publicly-funded facilities. We propose a set-covering optimization model to assist health policy-makers in managing existing capacity in a better way. Decision-making should consider upgrading centers with better potential to reduce patient expenses and reallocating capacities from less preferred facilities. A multinomial logit choice model is used to predict the preferences. In this article, a brief background and literature survey along with the mixed integer linear programming (MILP) optimization model are presented. The working of the model is illustrated with the help of numerical experiments.