• Proceedings of the KIPE Conference
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• 2010.07a
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• pp.57-58
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• 2010

This paper proposes maximum torque control of IPMSM drive using optimal current. This control method is applicable over the entire speed range which considered the limits of the inverter's current and voltage rated value. For each control mode, a condition that determines the optimal d-axis current $i_d$ for maximum torque operation is derived. This paper considers the design and implementation of novel technique of high performance speed control for IPMSM using multi-MFC and ANN controller. Also, this paper proposes maximum control of IPMSM drive using approximation method. This method is decreased the burden of digital signal process(DSP) in calculation of optimal current. This paper proposes the analysis results to verify the effectiveness of the MFC and ANN controller. Also it verifies the validity of maximum torque control of IPMSM drive with optimal current.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.2
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• pp.89-97
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• 2006

Interior permanent magnet synchronous motor(IPMSM) has become a popular choice in electric vehicle applications, due to their excellent power to weight ratio. The paper is proposed maximum torque control of IPMSM drive using learning mechanism-fuzzy neural network(LM-FNN) controller and artificial neural network(ANN). The control method is applicable over the entire speed range and considered the limits of the inverter's current and voltage rated value. For each control mode, a condition that determines the optimal d-axis current $i_{d}$ for maximum torque operation is derived. This paper considers the design and implementation of novel technique of high performance speed control for IPMSM using LM-FNN controller and ANN controller. The hybrid combination of neural network and fuzzy control will produce a powerful representation flexibility and numerical processing capability. Also, this paper is proposed speed control of IPMSM using LM-FNN and estimation of speed using ANN controller. The back propagation neural network technique is used to provide a real time adaptive estimation of the motor speed. The proposed control algorithm is applied to IPMSM drive system controlled LM-FNN and ANN controller, the operating characteristics controlled by maximum torque control are examined in detail. Also, this paper is proposed the analysis results to verify the effectiveness of the LM-FNN and ANN controller.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.9 no.1
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• pp.10-15
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• 2009

With the development of techniques, robots are getting smaller, and the number of robots needed for application is greater and greater. How to coordinate large number of autonomous robots through local interactions has becoming an important research issue in robot community. Swarm Robot Systems (SRS) is a system that independent autonomous robots in the restricted environments infer their status from pre-assigned conditions and operate their jobs through the cooperation with each other. In the SRS, a robot contains sensor part to percept the situation around them, communication part to exchange information, and actuator part to do a work. Especially, in order to cooperate with other robots, communicating with other robots is one of the essential elements. Because Bluetooth has many advantages such as low power consumption, small size module package, and various standard protocols, it is rated as one of the efficient communicating technologies which can apply to small-sized robot system. In this paper, we will develop Bluetooth communicating system for autonomous robots. And we will discuss how to construct and what kind of procedure to develop the communicating system for group behavior of the SRS under intelligent space.

• International Journal of Fuzzy Logic and Intelligent Systems
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• v.7 no.1
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• pp.17-21
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• 2007

Multi-Agent Robotic System (MARS) is a system that independent autonomous robots in the restricted environments infer their status from pre-assigned conditions and operate their jobs through the cooperation with each other. In the MARS, a robot contains sensor part to percept the situation around themselves, communication part to exchange information, and actuator part to do given work. Especially, in order to cooperate with other robots, communicating with other robots is one of the essential elements. Because Bluetooth has many advantages such as low power consumption, small size module package, and various standard protocols, Bluetooth is rated as one of the efficient communicating technologies which can apply to small-sized robot system. In this paper, we will develop Bluetooth communicating system for autonomous robots. For the purpose, the communication system must have several features-separated module, flexible interface. We will discuss how to construct and what kind of procedure to develop the communicating system.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.17 no.12
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• pp.1238-1245
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• 2007

A very abnormal vibration was occurred at the LP(low pressure) turbine continuously during the pre-operation for a 550MW class USC(ultra super critical) steam turbine. This vibration was initiated at the rotating speed of about 3,450 rpm and then the vibration amplitude was highly increased the number by $2{\sim}3$ times with the increase of the rotating speed to the rated speed (3,600 rpm). In this paper, this abnormal vibration named spike vibration. This spike vibration was caused by the rubbing between the rotating bucket tip seal and the lower half of spill strip. Also, this paper presents the mechanism of the spike vibration and the proper method to eliminate this abnormal vibration problem. This result would be good practice to find the solution of similar high vibration in the USC steam turbines for power plant as well as industrial rotating machineries.

• New & Renewable Energy
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• v.6 no.4
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• pp.50-60
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• 2010

With the development of wind industry, rated power of the wind turbine also increases gradually. Accordingly, size of the wind turbine tower is becoming larger. Tower base diameter of the 2MW wind turbine is about 4m. Larger tower is expected for 4MW or 5MW turbines. Due to limitation of transportation, new type of tower with smooth transportation and effective cost is needed. In this work, a hybrid tower consisting of steel and concrete is designed and analyzed. The optimum ratio of steel and concrete of the hybrid tower is calculated as well as the thickness of the concrete part. Different FE analysis including modal analysis, buckling analysis and static analysis are performed to check the design of hybrid tower comparing with the steel tower. Redesign is also expected after various analyses.

• Korean Journal of Optics and Photonics
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• v.11 no.3
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• pp.193-197
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• 2000

A polarized mode convertible, wavelength tunable optical filters with acoustic barriers and acousto-optic effect have been produced in LiNb03 substrate utilizing the Ti double diffusion technique. Polarization conversion in excess of 81 % and a spectral width of -200 kHz (-1.83 nm) were achieved at a wavelength of 1551.6 nm and RF frequencies of 173.07 kHz and 173.05 kHz for both transverse electric (TE) and transverse magnetic (lM) input polarizations, respectively. The electrical driving power was 10.97 mW and reduced to about 10% of one for an optical filter without an acoustic barrier. A linear tuning rate of 8.2 nmlMHz and sidelobe intensity of -4 dB was demonstrated. rated.

• Journal of the Korean Society of Clothing and Textiles
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• v.11 no.2 s.24
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• pp.1-11
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• 1987

The purpose of this study was to develope a questionaire measuring clothing behavior of elementary school children. At first, after pretest, the clothing behavior questionaire consisted of 70 items which were devidad. into 7 subscales i.e. Clothing interest. Clothing satisfaction. Clothing management, Clothing sex-role. Clothing comfort. Clothing conformity. and Clothing independence. Each item was rated on a 3-point scale. Samples were 447 boys and girls (4 th, 5 th, 6 th grade) of three elementary schools in Seoul. Korea. The data were analyzed by item analysis and factor analysis. Factor analysis was useful in attempting to establish contruct validity. Item validity was examined based on the correlation coefficients and item discriminating power through the chi-square. Reliability was examined based on the Cronbach's Alpha Reliability Coefficient and test-retest method. With this analysis the subscales were reconstructed to following 6 factors. Clothing conformity items were not clustered by the factor analysis. 52 items of 6 factors selected by the analysis. The factors characteristics were as follows: 1. Clothing interest (10 items) 2. Clothing satisfaction (11 items) 3. Clothing management (8 items) 4. Clothing sex-role (12 items) 5. Clothing comfort (6 items) 6. Clothing independence (5 items)

• Journal of Applied Reliability
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• v.15 no.3
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• pp.139-144
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• 2015

Track drive unit adopted in the small sized excavator generally have been used in the construction equipment under the 10 tons as the driving device with forwarding and reversing of excavator. It is required to study the accelerated life test applied by over torque and speed to test the durability life test reflected the many driving modes of small sized excavator and also need to equip the comprehensive performance and life test equipments to do the various performance tests. This study had analyzed the failure modes of the components, and calculated the equivalent loads investigated the used loads in the real field conditions and elicits the acceleration factor adopted in the inverse power model. Also, this study have considered the changes of the acceleration factor and the durability test time in the case of the rotary group and the bearing through analyzing the main failure modes. It was calculated the no failure test time about 2 samples and confidence level 90% and elicited the accelerated life time 720 hours.

• Proceedings of the KIEE Conference
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• 1994.07b
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• pp.1574-1576
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• 1994

$SF_6$ gas has become an important insulation medium in modern electric power apparatus, because of its high insulation withstand levels and good arc quenching capability. For the application of $SF_6$ gas in GIS the estimation of insulation properties is a fundamental point. Moreover the reduction of withstand levels in case of inhomogeneous fields caused by particles or fixed protrusions is of special interest. It is known that the presence of free conducting particles in GIS can significantly lower the insulating level of $SF_6$ gas at elevated pressure and also it has been recently shown that dielectric strength is greatly reduced by fast transients such as disconnector surges where metallic particles are involved. In this paper, we have disigned the particle test chamber rated 362kV for the purpose of investigating the discharge characteristics in SF6 gas where inhomogenius fields are caused by metallic particles.