• Korean Chemical Engineering Research
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• v.46 no.2
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• pp.233-247
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• 2008

Process monitoring technology is able to detect the faults and the process changes which occur in a process unpredictably, which makes it possible to find the reasons of the faults and get rid of them, resulting in a stable process operation, high-quality product. Statistical process monitoring method based on data set has a main merit to be a tool which can easily supervise a process with the statistics and can be used in the analysis of process data if a high quality of data is given. Because a real process has the inherent characteristics of nonlinearity, non-Gaussianity, multiple operation modes, sensor faults and process changes, however, the conventional multivariate statistical process monitoring method results in inefficient results, the degradation of the supervision performances, or often unreliable monitoring results. Because the conventional methods are not easy to properly supervise the process due to their disadvantages, several advanced monitoring methods are developed recently. This review introduces the theories and application results of several remarkable monitoring methods, which are a nonlinear monitoring with kernel principle component analysis (KPCA), an adaptive model for process change, a mixture model for multiple operation modes and a sensor fault detection and reconstruction, in order to tackle the weak points of the conventional methods.

• Journal of The Korean Association of Information Education
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• v.25 no.5
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• pp.791-801
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• 2021

In this paper, an educational case that can be applied as artificial intelligence literacy education for preservice teachers and incumbent teachers was studied. To this end, a case of educating the operating principle of an artificial neural network that recognizes images is proposed. This training case focuses on the basic principles of artificial neural network operation and implementation, and applies the method of finding parameter optimization solutions required for artificial neural network implementation in a spreadsheet. In this paper, we focused on the artificial neural network of supervised learning method. First, as an artificial neural network principle education case, an artificial neural network education case for recognizing two types of images was proposed. Second, as an artificial neural network extension education case, an artificial neural network education case for recognizing three types of images was proposed. Finally, the results of analyzing artificial neural network training cases and training satisfaction analysis results are presented. Through the proposed training case, it is possible to learn about the operation principle of artificial neural networks, the method of writing training data, the number of parameter calculations executed according to the amount of training data, and parameter optimization. The results of the education satisfaction survey for preservice teachers and incumbent teachers showed a positive response result of over 70% for each survey item, indicating high class application suitability.

• ETRI Journal
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• v.27 no.3
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• pp.312-318
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• 2005

Mid-span spectral inversion (MSSI) has to utilize high optical pump power, for its operation principle is based on a nonlinear optical wavelength conversion. In this paper, a low pump-power operation of MSSI-based chromatic dispersion compensation (CDC) has been achieved successfully, for the first time to our knowledge, by introducing a noise pre-reduction scheme in cascaded wavelength conversions with periodically poled $LiNbO_3$ waveguides at a relatively low operation temperature. As preliminary studies, phase-matching properties and operation-temperature dependence of the wavelength converter (WC) were characterized. The WC pumped at 1549 nm exhibited a wide conversion bandwidth of 59 nm covering the entire C-band and a conversion efficiency of -23.6 dB at 11 dBm pump power. CDC experiments were implemented with 2.5 and 10 Gb/s transmission systems over 100 km single-mode fiber. Although it is well-known that the signal distortion due to chromatic dispersion is not critical at a 2.5 Gb/s transmission, the clear recovery of eye patterns was identified. At 10 Gb/s transmission experiments, eye patterns were retrieved distinctly from seriously distorted ones, and notable improvements in bit-error rates were acquired at a low pump power of 14 dBm.

• Journal of Electrical Engineering and Technology
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• v.9 no.6
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• pp.2004-2012
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• 2014

Energy storage devices are necessary to obtain stable utilization of renewable energy sources. When black-out occurs, distributed renewable power sources with energy storage devices can operate under standalone mode as uninterruptable power supply. This paper proposes a dynamic response analysis with small-signal modeling for the standalone operation of a photovoltaic power generation system that includes a bidirectional charger/discharger with a battery. Furthermore, it proposes a DC-link voltage controller design of the entire power conditioning system, using the storage current under standalone operation. The purpose of this controller is to guarantee the stable operation of the renewable source and the storage subsystem, with the power conversion of a very efficient bypass-type PCS. This paper presents the operating principle and design guidelines of the proposed scheme, along with performance analysis and simulation. Finally, a hardware prototype of 1-kW power conditioning system with an energy storage device is implemented, for experimental verification of the proposed converter system.

• Journal of Electrical Engineering and Technology
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• v.13 no.2
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• pp.838-848
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• 2018

This paper proposes a single-phase buck-boost AC-AC converter. It consists of three legs with six switching units (each unit is composed of an active switch and a diode) and its input and output ports share a common ground. It can provide buck-boost voltage operation and immune from shoot-through problem. Since only two switching units are involved in the current paths, the conduction losses are low, which improves the system efficiency. The operation principle of the proposed circuit is firstly presented, and then, various operation conditions are introduced to achieve different output voltages with step-changed frequencies. Additionally, the parameters design and comparative analysis of the power losses are also given. Finally, experimental results verify the correctness of the proposed converter.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.1 no.1
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• pp.3-10
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• 1978

Human Engineering has an intention of design to keep the best condition of man-machine system. Hitherto the conception of design has been used to include existing engineering, as mechanical engineering and electric engineering. But the manufactured goods which to be made these process seem to be fully equipped on physical function, but faults come out discountent repeatedly to users. Accordingly, the development of industrial design has been demanded for improving functional design. It is considered that industrial design has aesthetical sensation. In actually, it must be 1. to provide for utility and safety, 2. easy for maintenance, 3. cheap at cost. 4. possible for sales appeal, 5. and good on appearance. As taking into consideration above five conditions, however, for 삯e sake of comprehend to human being about operating method of machinery and equipment, it should be reflected to design what kind of training way will be needed. Also, it must be considered what a certain extent would be occurred tiredness to human being. in other words. it should be considered the design to be possible the reflect to principle of motion economy, It should not be made adoption of human ability for the designed machinery, it must be adopted the method to consider the design on presuppose about human ability. For study of these actual fact, this paper is summarized the essence of human engineering, and also to find out the methodology as humanistic engineering, It is, Particularly, subdivisionization of operation in flow operation is essential direction of mechanization. Generally. as developing the subdivisionization of operation, it will be lack of satisfaction on operation which worker take charge of. The subdivisionization of operation makes the operation to simple-repetitive, to lose the interest of worker and will be also come into question to the feeling of worker's livelihood. It is human's fundamental desire to have get skilful function or special technique. But the subdivisionization of operation hold in those human's fundamental desire and so that it will likely to lose the sorority of living by this fact. Accordingly, this paper have an operation to hold out the methodology on presuppose about human ability.

• Proceedings of the IEEK Conference
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• 2003.07c
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• pp.2935-2938
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• 2003

A new Valley-fill circuit for improving PF(power factor) is proposed in this paper. The proposed topology combines Valley-fill rectifier and an additional inductor for boosting. In the proposed circuit, a shapc of input current is related to the PWM duty cycle. The boosting inductor makes improve PF by the electric charge transfer action. The operation principle and the shape of input current arc analyzed as applied the boosting inductor. The optimum value of boosting inductor is determined. A 100W single-stage converter has been designed and tested. Experimental results are presented to verify the validity of the proposed converter.

• Proceedings of the KIPE Conference
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• 1997.07a
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• pp.322-331
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• 1997

In this paper, Instantaneous voltage control method is proposed to reduce the torque ripple of a switched reluctance motor. This method is based on the sum control of the square of the phase currents in proposed converter. A proposed prototype SRM drive circuit is given and it's operation is analyzed. The experiments and simulations are performed to verify the capability of proposed principle.

• Proceedings of the KIPE Conference
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• 2003.07a
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• pp.58-61
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• 2003

In this paper, resonant Characteristics of the soft switched asymmetrical half bridge converter is analysis. The operation principle for proposed converter is explained in steady state and its circuit is analyzed by means of equivalent circuit. Experimental results carried out on a system prototype are included in this paper.

• 제어로봇시스템학회:학술대회논문집
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• 1991.10b
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• pp.1718-1723
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• 1991

The determination of a production sequence is an important problem in a batch process operation. In this paper a new algorithm for a near optimal production sequence of N product in an M unit serial multiproduct batch process is proposed. The basic principle is the same as that of Johnson's algorithm for two-unit UIS system. Test results on a number of selected examples exhibit the superiority over previously reported results. In addition, a tabulation technique is presented to calculate the makespan of a given sequence of production for all processing units under UIS mode.