• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.199-199
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• 2000

Most of linear time-varying(LTV) systems except special cases have no general solution for the dynamic equations. Thus, it is difficult to design time-varying controllers in analytic ways, and other control design approaches such as robust control have been applied to control design for uncertain LTI systems which are the approximation of LTV systems have been generally used instead. A robust control method such as quantitative feedback theory(QFT) has an advantage of guaranteeing the stability and the performance specification against plant parameter uncertainties in frozen time sense. However, if these methods are applied to the approximated linear time-invariant(LTI) plants which have large uncertainty, the designed control will be constructed in complicated forms and usually not suitable for fast dynamic performance. In this paper, as a method to enhance the fast dynamic performance, the approximated uncertainty of time-varying parameters are reduced by the proposed QFT parameter-scheduling control design based on radial basis function (RBF) networks for LTV systems with bounded time-varying parameters.

• Journal of Intelligence and Information Systems
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• v.7 no.1
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• pp.81-95
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• 2001

Plant construction projects usually take much higher uncertainty and risks than the projects from other domains. This implies the importance of plant construction project management should be more emphasized than the other domain. Especially, the overall successes of the projects often depend on the performance of process planning and scheduling performed at the initial stage of the project. However, most plant construction projects suffer great difficulties in establishing proper process planning and scheduling timely because of unstructureness and dynamicity of environment of the project itself In this paper, we propose a knowledge-based process planning and scheduling approach in a plant construction domain to cope this problem. First, we modulize process planning knowledge and present the knowledge representation scheme. Second, we propose an inferencing mechanism to build a process planning for plant construction based on the represented process planning knowledge. Since our approach automate the initial process planning, which was usually done by manual way, it can improve the correctness and also completeness of the process plan and schedule by reducing the time to plan and allowing simulations on the various situation. We also design and implement this our approach as a real working system, and it is successfully applied to real plant construction cases from a leading construction company in Korea. Based on this success, we expect our approach can be easily applied to the projects of other areas, while contributing to enhancement in productivity and quality of project management.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.32 no.3
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• pp.40-48
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• 2009

In this article, scheduling of a casting sequence is studied in a casting foundry which must deliver products according to the Just-in-time(JIT) production policy of a customer. When a foundry manufactures a variety of casts with an identical alloy simultaneously, it frequently faces the task of production scheduling. An optimal casting schedule should be emphasized in order to maximize the production rate and raw material efficiency under the constraints of limited resources; melting furnaces and operation time for a casting machine. To solve this practical problem-fulfilling the objectives of casting the assigned mixed orders for the highest raw material efficiency in a way specified by the customer's JIT schedule, we implement simple integer programming. A simulation to solve a real production problem in a typical casting plant proves that the proposed method provides a feasible solution with a high accuracy for a complex, multi-variable and multi-constraint optimization problem. Employing this simple methodology, a casting foundry having an automated casting machine can produce a mixed order of casts with a maximum furnace utilization within the due date, and provide them according to their customer's JIT inventory policy.

• Journal of the Korean Society of Industry Convergence
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• v.24 no.3
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• pp.333-341
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• 2021

Irrigation scheduling is a water management strategy of applying the proper amount of water in a plant's root zone at the right time to maximize profit. We conducted an experimental evaluation of the response of soybean, sorghum, and sesame to an irrigation scheduling scheme. The soil water contents were adjusted in the root zone between 20% and 28% to reflect changes in crop water consumption. The other ones fixed at 25% during the whole growing season were compared to evaluate the effectiveness of irrigation scheduling. Surface drip irrigation (SDI) were employed as an irrigation method. For all three crops, the evapotranspiration (ET) was the greatest at flowering stage (6.93 mm), followed by vegetative growth stage (5.00 mm) and maturity stage (2.53 mm). The irrigation amount was significantly reduced by 21.8% (soybean), 22.2% (sorghum), and 16.1% (sesame), respectively, compared with the ones at constant soil water content treatment. Their water use efficiency (WUE) were also much higher than the controls: 2.65-fold increase at soybean, 1.82-fold increase at sorghum, and 1.47-fold increase at sesame. These results showed that an effective irrigation scheduling on upland crops (soybean, sorghum, sesame) could increase crop yield while minimizing water use.

• 제어로봇시스템학회:학술대회논문집
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• 1989.10a
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• pp.841-843
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• 1989

Aspects of modelling, performance monitoring, control and optimisation are discussed, with particular reference to the application of SPEEDUP. A new facility is described which allows SPEEDUP to operate in conjunction with other systems and several examples are briefly given of its power and flexibility. In particular, its use in on-line applications alongside plant management and distributed control systems is described and how it can be used in scheduling/sequencing problems in investigating batch and cyclic problems.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.04a
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• pp.301-305
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• 1992

A mold plant is characterized by complex processes, frequent schedule changes, and lots of troubles. In order to control the production in mold plant efficiently, huge amount of informations are to be managed in the appropriate way. In this paper, a modular software system for production control is described, which is located between a higher level production planning system and a process control system. It contains the functions such as order processing, operations scheduling and control, tool managemant, NC program managememt including DNC functions, production data acquisition and progress control and statistics.

• Korean Journal of Construction Engineering and Management
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• v.14 no.4
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• pp.140-151
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• 2013

In 2011 and 2012, Korean construction firms awarded around $ 64.5. Billion each year from the overseas market in 2011. This contract value accounted for overwhelming portion of total overseas construction contract values, and this growth is expected to continue for the next decade. However, contract scopes awarded to the Korean construction firms mainly involve detailed design and construction phases due to their competitiveness for the construction techniques. In other words, front-end-engineering-design and construction project management are not considered part of core business due to the lack of project management skills and experience. The researchers focused on development of construction sequence model required to improve construction planning and scheduling skills for the Korean construction firms. The model identifies critical work items and the sequence throughout project execution process. In addition, the researchers developed a risk evaluation method by applying fuzzy theory to the critical construction activities for the industrial plant construction projects. Developed methodology will help project practitioners to develop project schedule in a timely and effe ctive manner and evaluate project risks associated with scheduling process for the industrial plant construction projects.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.34 no.5
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• pp.193-200
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• 1985

Increased attention has been given in recent years to the use of pumped hydrostorage plant to meet the requirements for peak generation and bottom pumping. Once a pumped hydrostorage plant is installed, its economic operation as an integral component of a steam generating system requires the selection of a pumping and generating schedule which will result in the most effective use of the hydro generating capacity. The general object of coordination of pumped hydrostorage plants with electric power system is the minimization of the overall procduction cost and the maximization of generation reserves. This paper presents a method for the optimal scheduling of pumped hydrostorage plant and a computer program which determines weekly operating schedules for a pumped hydrostorage plant by dynamic programming method.

• Proceedings of the Korean Society for Agricultural Machinery Conference
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• 1993.10a
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• pp.952-965
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• 1993

A simulation modeling is necessary for the optimal design of a rice processing plant, which consists of a facility (a silo system) of rice drying and storage and a rice mill plant. In a rice processing plant, the production scheduling and the decision on capcity of each unit based on a queuing theory is very important and difficult. In this study a process-oriented simulation model was developed for the design of a rice drying and storage system with SLAMSYSTEM. The simulation model is capable of simulating virtually all the processing activities and provides work schedules which minimize total processing time , mean flow time and bottleneck of the plant system and estimate drying time for a batch in a drying silo. Model results were used for determination the size and capacity of each processing unit and for analyzing the performance of the plant . The developed model was actually applied to construct a grain silo system for rice drying and storage.

• International Journal of Control, Automation, and Systems
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• v.3 no.3
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• pp.493-501
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• 2005

A power plant simulation tool ('PowerSim') has been developed with 10 years experience from the development of a plant simulator for efficient modeling of a power plant. PowerSim is the first developed tool in Korea for plant simulation with various plant component models, instructor station function and the Graphic Model Builder (GMB). PowerSim is composed of a graphic editor using general purpose design software, a netlist converter, component models, the scheduler, Instructor Station and an executive. The graphic editor generates a netlist that shows the connection status of the various plant components from the Simdiagram, which is drawn by Icon Drag method supported by GUI environment of the PowerSim. Netlist Converter normalizes the connection status of the components. Scheduler makes scheduling for the execution of the device models according to the netlist. Therefore, the user makes Simdiagram based on the plant Pipe and Instrument Drawing (P&ID) and inputs the plant data for automatic simulating execution. This paper introduces Graphic Model Builder (GMB), instructor station, executive and the detailed introduction of thermal-hydraulic modeling. This paper will also introduce basic ideas on how the simulation Diagram, based on netlist generated from general purpose design software, is made and how the system is organized. The developed tool has been verified through the simulation of a real power plant.