• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 1992년도 한국자동제어학술회의논문집(국내학술편); KOEX, Seoul; 19-21 Oct. 1992
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• pp.675-679
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• 1992

In industry, the speed control of single-phase induction motor in domestic use is generally controlled by a simple ON-OFF or PID control method. However, in this case, in order to have a good speed regulating characteristics, itself should be modified in accordance with the optimum PID factors which are varied each time operating speed changes. Shortening the development time and saving the cost which are needed to modify the controller is a major problem to be solved now in industry. In order to alleviate the above difficulties, it is proposed to apply adaptive control technique using MRFAC(Model Reference Following Adaptive Control) for the speed control of single-phase induction motor which has scarcely been studied. In this paper, the above speed control technique is achieved using MCS-96 one chip micro controller with a good speed control characteristics and it is expetted to open a wide application field in the speed control of single-phase induction motor in the future.

• Journal of Electrical Engineering and Technology
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• 제4권3호
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• pp.389-395
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• 2009

Industrial motors are subject to incipient faults which, if undetected, can lead to motor failure. The necessity of incipient fault detection can be justified by safety and economical reasons. The technology of artificial neural networks has been successfully used to solve the motor incipient fault detection problem. This paper develops inexpensive, reliable, and noninvasive NN based incipient fault detection scheme for small and medium sized induction motors. Detailed design procedure for achieving the optimal NN model and Principal Component Analysis for dimensionality reduction is proposed. Overall thirteen statistical parameters are used as feature space to achieve the desired classification. GFFD NN model is designed and verified for optimal performance in fault identification on experimental data set of custom designed 2 HP, three phase 50 Hz induction motor.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2011년도 춘계 학술논문 발표대회 1부
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• pp.111-114
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• 2011

Waterprooping Method with sheet need to study technology and multilateral verification considering the arctic conditions as low temperature and humidity, which is the result only considered of material aspects without environmental condition in construction But there are no measures up until now. To solve this problem by using high frequency induction heating method developed waterproof sheets, cold (5 ℃ or less) can be applied in a more stable environment, water-resistant materials and construction methods were studied for development. The results of the test showed that high frequency induction heating method is effective for usability in low temperature condition and securement of proper quality than existing Waterprooping Method with sheet need.

• 여성건강간호학회지
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• 제29권3호
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• pp.229-238
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• 2023

Purpose: This study analyzed the effects of virtual reality simulation-based problem-based learning on nursing students' critical thinking ability, problem-solving ability, and self-efficacy in the nursing care of women undergoing induction of labor. Methods: A nonequivalent control group pretest and posttest design was employed. The study participants included 52 nursing students (24 in the experimental group and 28 in the control group). The experimental group took a problem-based learning (PBL) class in the first week, and then engaged in self-directed learning using virtual reality simulation. In the second week, lectures about emergency nursing care for induction of labor and drug administration were given. The control group participated in PBL in the first week and lectures in the second week. The study was conducted from April 17 to May 19, 2023. Data were analyzed using the chi-square test, Fisher exact test, analysis of variance, and the independent t-test. Results: Before-and-after differences between the two groups were statistically significant in problem solving ability (t=-5.47, p<.001) and self-efficacy (t=-5.87, p<.001). Critical thinking ability did not show a statistically significant difference between the two groups. The score for satisfaction with the virtual reality simulation program was 3.64±5.88 out of 5 in the experimental group. Conclusion: PBL education using a virtual reality simulation was found to be an effective way of teaching. Although convenience sampling was used, PBL education using virtual reality can be used as an educational strategy to enhance nursing students' problem-solving ability and self-efficacy.

• Journal of Power Electronics
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• 제15권4호
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• pp.1119-1130
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• 2015

This study investigates the multi-objective fuzzy optimization of crowbar resistance for the doubly fed induction generator (DFIG) low-voltage ride-through (LVRT). By integrating the crowbar resistance of the crowbar circuit as a decision variable, a multi-objective model for crowbar resistance value optimization has been established to minimize rotor overcurrent and to simultaneously reduce the DFIG reactive power absorbed from the grid during the process of LVRT. A multi-objective genetic algorithm (MOGA) is applied to solve this optimization problem. In the proposed GA, the value of the crowbar resistance is represented by floating-point numbers in the GA population. The MOGA emphasizes the non-dominated solutions and simultaneously maintains diversity in the non-dominated solutions. A fuzzy-set-theory-based is employed to obtain the best solution. The proposed approach has been evaluated on a 3 MW DFIG LVRT. Simulation results show the effectiveness of the proposed approach for solving the crowbar resistance multi-objective optimization problem in the DFIG LVRT.

• International Journal of Control, Automation, and Systems
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• 제3권1호
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• pp.79-86
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• 2005

In this paper, an estimator scheme for the rotor speed and flux of an induction motor is proposed on the basis of a fourth-order electrical model. It is assumed that only the stator currents and voltages are measurable, and that the stator currents are bounded. There are a number of common terms in the motor dynamics, and this is utilized to find a simple error model involving some auxiliary variables. Using this error model, the state estimation problem is converted into a parameter estimation problem assuming that the rotor speed is constant. Some stability properties are given on the basis of Lyapunov analysis. In addition, the rotor resistance, which varies with the motor temperature, can also be estimated within the same framework. The effectiveness of the proposed scheme is demonstrated through computer simulations and experiments.

• 전력전자학회:학술대회논문집
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• 전력전자학회 2001년도 전력전자학술대회 논문집
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• pp.405-408
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• 2001

This paper investigates the problem of the speed estimation of conventional speed sensorless stator flux-oriented induction machine drive in the field weakening region and proposes a new speed estimation scheme to estimate speed exactly in transients in the field weakening region. The error included in the estimated rotor speed is removed by not a low pass filter but Kalman filter.

• 논리연구
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• 제12권2호
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• pp.59-88
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• 2009

귀납추론은 연역추론이 아니기 때문에 연역적으로 정당화될 수 없다. 또한 귀납추론을 귀납적으로 정당화하는 것은 순환적이다. 따라서 흄은 귀납추론을 합리적으로 정당화할 수 없다고 주장한다. 흄이 이와 같은 귀납의 문제를 제기한 이후 오랜 동안 많은 철학자들이 이 문제를 해결하고자 시도해 왔다. 그럼에도 불구하고, 아직껏 대다수의 철학자들이 동의하는 해결책이 제시되지 않고 있다. 셀라스에 따르면 귀납의 문제는 이론추론이 아니라 오직 실천추론을 통해서만 해결할 수 있다. 이 논문은 셀라스가 제안한 실천추론에 의한 귀납의 정당화를 좀 더 명확한 형태로 발전시켜 설명함으로써 그의 해결책이 귀납의 문제에 대한 근본 해결책임을 주장한다.

• 전력전자학회:학술대회논문집
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• 전력전자학회 1998년도 Proceedings ICPE 98 1998 International Conference on Power Electronics
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• pp.392-397
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• 1998

This paper proposes a programmable low pass filter(LPF) to estimate stator flux for speed sensorless stator flux orientation control of induction motors. The programmable LPF is developed to solve the dc drift problem associated with a pure integrator and a LPF with fixed pole. The pole of the programmable LPF is located far from the origin to decrease the time constant as speed increases. The programmable LPF has the phase and the magnitude compensator to exactly estimate stator flux in a wide speed range. So, the drift problem is much improved and the stator flux is exactly estimated in the wide speed range.

• 한국소성가공학회:학술대회논문집
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• 한국소성가공학회 2008년도 추계학술대회 논문집
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• pp.329-332
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• 2008

Nowadays, It is required human body-friendly, good mechanical properties, and economical efficiency material, simultaneously. The material to meet above requirement condition rear up high nitrogen stainless steel(HNS). However, HNS have a lot of problem such as poor workability, hot crack sensitivity. So, It is needed the condition of plastic working to overcome above many problem. In this study, VIM ingot with 100kg was made by pressurized vacuum induction melting. And then, The slab perform for hot rolling was prepared by open-die forging. Hot rolling process was performed by computer simulation according to change of height reduction, rolling temperature, heating numbers, rolling pass and so forth. The results of analysis were investigated between analysis and lab-scale rolling product.