• Journal of the Korean Society for Precision Engineering
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• v.14 no.1
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• pp.101-107
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• 1997

Recently, as the raw water quality becomes to be polluted and the seasonal and local variation of water quality becomes to be severe, an exact control of coagulant dosing have been required in the water treat- ment plant. The amounts of coagulant is related to the raw water quality such as turbidity, alkalinity, water temperature, pH and edectrical conductivity. However the process of chemical reaction has not been clarified so far, so the dosing rate has been decided by jar-test, which is taken one or two hours. For the sake of this coagulant dosing control, fuzzy neural network to fuse fuzzy logic and neural network was proposed, and the scheme was applied to automatic determination of coagulant dosing rate. This controller can automatically identify the if-then rules and tune the membership functions by utilizing expert's cintrol data. It is shown that determination of coagulant dosing rate according to real time sensing of water quality is very effect.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.11
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• pp.1036-1042
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• 2007

It is rather difficult to improve flight control computer(FLCC) hardware(H/W) development schedule due to lack of commercial off-the-self(COTS) tools or target specific tools. Thus, it is suggested to develop an enhanced process utilizing modeling, simulation and virtual reality tools. This paper presents H/W design process enhancement tool(PET) for FLCC design requirements such as FLCC input/output(I/O) signal flow, I/O fault detection, failure management algorithm, circuit logic, PCB assembly configuration and installation utilizing simulation and visualization in virtual space. New tool will provide simulation capability of various FLCC design configuration including shop replaceable unit(SRU) level assembly/dis-assembly utilizing open flight format 3-D modeling data.

• Proceedings of the KIEE Conference
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• 2007.04c
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• pp.97-99
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• 2007

This paper presents a fuzzy logical control method to implement an on-line optimum efficiency control for Permanent Magnet Synchronous Motor. This method real-timely adjusts the output voltage of the inverter system to achieve the optimum running efficiency of the whole system. At first, the input power is calculated during the steady state in the process of efficiency optimizing. To exactly estimate the steady state of the system, this section needs check up the speed setting on timely. The second section is to calculate input power of dc-bus. The exact measurement of the voltage and current is the vital point to acquire the input power. The third section is the fuzzy logic control unit, which is the key of the whole drive system. Based on the change of input power of dc-bus and output voltage, the variable of output voltage is gained by the fuzzy logical unit. With the on-line optimizing. the whole system call fulfill the minimum input power of dc-bus on the running state. The experimental result proves that the system applied the adjustable V/f control method and the efficiency-optimizing unit possesses optimum efficiency, and it is a better choice for simple variable speed applications such as fans and pump.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.16 no.1
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• pp.44-51
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• 2016

Recently, artificial intelligence has reached the level of top information technologies that will have significant influence over many aspects of our future lifestyles. In particular, in the fields of machine learning technologies for classification and decision-making, there have been a lot of research efforts for solving estimation and control problems that appear in the various kinds of portfolio management problems via data-driven approaches. Note that these modern data-driven approaches, which try to find solutions to the problems based on relevant empirical data rather than mathematical analyses, are useful particularly in practical application domains. In this paper, we consider some applications of modern data-driven machine learning methods for portfolio management problems. More precisely, we apply a simplified version of the sparse Gaussian process (GP) classification method for classifying users' sensitivity with respect to financial risk, and then present two portfolio management issues in which the GP application results can be useful. Experimental results show that the GP applications work well in handling simulated data sets.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.33 no.4
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• pp.326-330
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• 2020

Small-scale production control systems for smart manufacturing are becoming increasingly necessary as the manufacturing industry seeks to maximize manufacturing efficiency as the demand for customized product production increases. Correspondingly, the development of an embedded system to realize this capability is becoming important. In this study, we developed an embedded system based on an open source system that is cheaper than a widely applied programmable logic controller (PLC)-based production control system that is easier to install, configure, and process than a conventional relay control panel. This embedded system is system is based on a low-power, high-performance Cortex M4 processor and can be applied to smart manufacturing. It is designed to improve the development environment and compatibility of existing PLCs, control small-scale production systems, and enable data collection through heterogeneous communication. The real-time response characteristics were confirmed through an operation test for input/output control and data collection, and it was confirmed that they can be used in industrial sites.

• Journal of the Korean Institute of Intelligent Systems
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• v.5 no.3
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• pp.64-72
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• 1995

This paper proposes how to tune the gains of PI controllers in case of gain change in a process control system. Controllers of PI type have been used in industry and the gains of the controllers have been tuned by expert engineers. It, therefore, takes much time and efforts to tune the controllers. It is more difficult to find gains of multi-loop processes. The tuning method of a fuzzy tuner in this paper is developed based on the assumptions that the PI controllers are of analog type and are tuned off-line, and that the characteristic values must be supplied for the tuner. A Tuner using Fuzzy Logic(FLT1 is capable of showing presentlpast states of a process control system and finding gains of PI controllers. The verfication of the FLT is shown by various experiments.

• Asia pacific journal of information systems
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• v.13 no.1
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• pp.73-101
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• 2003

Firms can create additional customer values by changing the visibility characteristic of business transactions. Both visible and invisible transactions can provide distinctive values to the customers. Visible transactions are those that are open to the customer: the customer can see the detailed logic of the transaction and may manipulate specific variables to control the transaction process. Invisible transactions mean that customers have little ability to control the transaction flow and may even be insulated from seeing the transaction. These invisible transactions will be taken care of only by suppliers, and be regarded as a process performed by suppliers. This paper pursues finding out the contingencies of successful transaction visibility change by answering to the following question; "when does increasing(or decreasing) transaction visibility make sense to customers?" This archival case study finds out that transaction visibility change should fit to the need and capabilities of customers. Increasing transaction visibility makes sense when customers need a certain supplier's performance and have a confidence in the capabilities of executing the performance. By the same token, decreasing transaction visibility makes sense when customers have substantial troubles in conducting their current transaction actions or when customers don't feel it necessary to conduct them separately because they can be derived from other action.

• Journal of the Korean Institute of Intelligent Systems
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• v.18 no.4
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• pp.488-493
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• 2008

A mathematical model of molten steel level for continuous casting process is presented, where the molten steel level, input and output flow in the mold, the relation between stopper position and input flow etc. are considered. The mathematical model is implemented and simulated by using MATLAB. Comparing the result of molten steel level from the simulator with that of real plant, the performance of the model is shown to be reasonable. By using this simulator, it is shown that PI controller with variable P gain, adjusted by fuzzy logic system, has better control result than conventional PI controller.

• Journal of The Korean Association of Information Education
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• v.14 no.2
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• pp.273-283
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• 2010

Emergent process or behaviour can be seen in many places, from any multicellular biological organism to traffic patterns, cities or organizational phenomena in computer simulations. Similarly, the concept of 'Green IT' refers to the way complex systems and patterns arise inevitably among groups due to environmental concerns in real world. Green IT has good possibility to evolve as very chaotic system, in which the number of interactions between components increases geometrically with the number of components, thus potentially allowing for many new types of behaviour to emerge. However, when Green IT system regards as a complexity one, there exits some attractors to derive and control the system. In this context, this paper presents a new model based on type-2 fuzzy logic system to identify and assess the attractors of Green IT system which correspond to Reach-Richness matrix of Green IT.

• The Journal of Korean Association of Computer Education
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• v.7 no.2
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• pp.77-84
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• 2004

In this thesis, We propose the self-directed learning and test-performing abilities assessment method to evaluate the learning and the test-performing abilities in which learners can not only control their own learning abilities for themselves, but also judge objectively learning and test-performing abilities. This method shows the membership degree of learning and test-performing abilities by using both the triangle-type membership function and the fuzzy logic. In addition, it gives the fuzzy grades to each item. The final membership degrees are calculated and the fuzzy grades are decided by the operation and composition of fuzzy relations on the membership degrees of learning and test-performing abilities. In this method, which is applicable to a writing subject for information searchers, learners are asked to analyse the membership degrees of the learning and test-performing abilities and the final fuzzy grades and to adjust a learning process for themselves.