• Journal of Korean Society of Industrial and Systems Engineering
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• v.27 no.4
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• pp.42-48
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• 2004

This paper concerns on a multiprocessor task scheduling problem with precedence relation, in which each task requires several processors simultaneously. Meta-heuristic generally finds a good solution if it starts from a good solution. In this paper, a tabu search is presented to find a schedule of minimal time to complete all tasks. A modified tabu search is also presented which uses a new initial solution based on the best solution during the previous run as the new starting solution for the next iteration. Numerical results show that a tabu search and a modified tabu search yield a better performance than the previous studies.

• Journal of information and communication convergence engineering
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• v.17 no.3
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• pp.198-204
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• 2019

In this study, the author introduces a supply-chain management (SCM) solution that connects suppliers, manufacturers, customers, and other companies within a transactional relationship to enable efficient inventory management and timely product supply, which ultimately maximizes corporate profits. This proposed solution exploits Fourth Industrial Revolution technologies, such as artificial intelligence (AI) and the Internet of Things (IoT), which provide solutions to complex management issues generated by the broader market. The goal of the current study was to develop an advanced and intelligent smart SCM solution that complies with logistics standards, to enhance the visibility, safety, and efficiency of a supply chain made up of manufacturers and suppliers. This smart SCM solution aims at maximizing corporate profits through efficient inventory management and timely supply of products, and solves the complex management problems caused by operating within a wide range of markets.

• Structural Engineering and Mechanics
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• v.72 no.4
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• pp.491-502
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• 2019

This paper explores the analytical buckling solution of rectangular thin plates by the finite integral transform method. Although several analytical and numerical developments have been made, a benchmark analytical solution is still very few due to the mathematical complexity of solving high order partial differential equations. In solution procedure, the governing high order partial differential equation with specified boundary conditions is converted into a system of linear algebraic equations and the analytical solution is obtained classically. The primary advantage of the present method is its simplicity and generality and does not need to pre-determine the deflection function which makes the solving procedure much reasonable. Another advantage of the method is that the analytical solutions obtained converge rapidly due to utilization of the sum functions. The application of the method is extensive and can also handle moderately thick and thick elastic plates as well as bending and vibration problems. The present results are validated by extensive numerical comparison with the FEA using (ABAQUS) software and the existing analytical solutions which show satisfactory agreement.

• Journal of Theoretical and Applied Mechanics
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• v.3 no.1
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• pp.1-15
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• 2002

Reduction methods for large structural systems have been reviewed. Mai emphasis is put on the dynamic reduction. Recently, the computing resources and technologies have been expanded so fast that the huge matrices Invoked In the analysis of structural system can be processed without serious difficulties. For most users, however, the computer facilities are limited and the system reductions in some forms are required. The reduction procedure in static problems is simple and straightforward. The major task is the book-keeping in computations. In dynamic problems and structural optimization. however. the problem is much more complicated. The problem is, in general, nonlinear and hence the exact solution is not available. Therefore, approximate solutions are sought in an iterative manner. A proper convergence criterion needs to be employed in order to get an accurate solution efficiently. Several research works have been reported fer the structural optimization combined with system reductions.

• Proceedings of the KIEE Conference
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• 2002.07b
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• pp.756-760
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• 2002

This study presents a solution to control a Permanent Magnet Synchronous Motor without sensors. The control method is the presented superposition principle. This method of sensorless theory is very simple to compute estimated angle. Therefore computing time to estimate angle is shorter than other sensorless method. The use of this system yields enhanced operations, fewer system components, lower system cost, energy efficient control system design and increased efficiency. A practical solution is described and results are given in this Study. The performance of a Sensorless architecture allows an intelligent approach to reduce the complete system costs of digital motion control applications using cheaper electrical motors without sensors. This paper deals with an overview of sensorless solutions in PMSM control applications whereby the focus will be the new Controller without sensors and its applications.

• Proceedings of the Society of Korea Industrial and System Engineering Conference
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• 2002.05a
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• pp.31-36
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• 2002

Product Liability(PL) is a legal policy to deal with global competition by improving domestic industrial competitive power and to reduce the cost of defect products. The purpose of this paper is to address the state of the art solutions to dispute on PL, in reality of a frequent occurrence of global product exchange focussing on product safety that is one of the most important functions of PL and to improve solution of the product safety and reliability responsive to PL. To minimize PL exposure, manufacturers should reflect comprehensive product safety and reliability concepts in establishing PL prevention policies. PL prevention policies are composed of administration system, product safety management system, and total quality management system in respect of prevention, safety, and defence.

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2002.04a
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• pp.199-205
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• 2002

This application study presents a solution to control a Permanent Magnet Synchronous Motor without sensors. The use of this system yields enhanced operations, fewer system components, lower system cost , energy efficient control system design and increased efficiency. The control method presented is field oriented control (FOC). The sinusoidal voltage waveforms are generated by the power module using the space vector modulation technique. A practical solution is described and results are given in this application Study. The performance of a Sensorless architecture allows an intelligent approach to reduce the complete system costs of digital motion control applications using cheaper electrical motors without sensors. This paper deals with an overview of sensorless solutions in digital motor control applications whereby the focus will be the new Controller without sensors and its applications.

• Transactions of the Korean Society of Mechanical Engineers
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• v.17 no.8
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• pp.2099-2109
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• 1993

A gas-fired 4RT absorption heat pump was designed as an air-conditioner for domestic use during the summer. The absorption heat pump is air-cooled. double-effect, $LiBr-H_{2}O$ system with parallel flow type. The performance of the absorption heat pump in the cooling mode of operation was investigated through cycle modeling and simulation to obtain the system characteristics with parameter changes. System parameters considered in this analysis were the inlet temperature of cooling air to the absorber, the working solution concentrations, the ratio of the amount of the weak solution from the absorber, and the LTD's of each heat exchange component. The optimum designs and operating conditions were determined based on the operating constraints and the coefficient of performance.

• Journal of the Korean Society of Safety
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• v.14 no.2
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• pp.70-76
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• 1999

In this paper, a mixed-integer programming approach is presented for adjusting the voltage profiles in a power system. The advent of large-scaled system makes the reactive power and voltage problem-an attempt to achieve an overall improvement of system security, service quality and economy-more complex and seriously, Although the problem is originally a nonlinear optimization problem, it can be formulated as a mixed integer linear programming(MILP) problem without deteriorating of solution accuracy to a certain extent. The MILP code is developed by the branch and bound process search for the optimal solution. The variable for modeling transformer tap positions is handled as discrete one, and other variables continuous ones. Numerical data resulting from case study using a modified IEEE 30 bus system with outaged line show that the MILP can produce more reductions of magnitude in the operating cost. The convergence characteristics of the results are also presented and discussed.

• Journal of Ocean Engineering and Technology
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• v.26 no.4
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• pp.8-14
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• 2012

Two dimensional nesting is a common problem in industries such as the shipbuilding, automotive, clothing, shoe-making, and furniture industries, in which various parts are cut off from stock or packed in a flat space while minimizing waste or unoccupied space. Nesting is known as an NP-complete problem, which has a solution time proportional to the superpolynomial of the input size. It becomes practically impossible to find an optimal solution using algorithmic methods as the number of shapes to nest increases. Therefore, heuristic methods are commonly used to solve nesting problems. This paper presents an expert system that uses a heuristic search method based on an evaluation function for nesting problems, in which parts and stock are represented by pixels. The system is developed in CLIPS, an expert system shell, and is applied to four different kinds of example problems to verify its applicability in practical problems.