• Journal of Power Electronics
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• v.5 no.2
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• pp.129-141
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• 2005

A high-performance robust hybrid speed controller for a permanent-magnet synchronous motor (PMSM) drive with an on-line trained neural-network model-following controller (NNMFC) is proposed. The robust hybrid controller is a two-degrees-of-freedom (2DOF) integral plus proportional & rate feedback (I-PD) with neural-network model-following (NNMF) speed controller (2DOF I-PD NNMFC). The robust controller combines the merits of the 2DOF I-PD controller and the NNMF controller to regulate the speed of a PMSM drive. First, a systematic mathematical procedure is derived to calculate the parameters of the synchronous d-q axes PI current controllers and the 2DOF I-PD speed controller according to the required specifications for the PMSM drive system. Then, the resulting closed loop transfer function of the PMSM drive system including the current control loop is used as the reference model. In addition to the 200F I-PD controller, a neural-network model-following controller whose weights are trained on-line is designed to realize high dynamic performance in disturbance rejection and tracking characteristics. According to the model-following error between the outputs of the reference model and the PMSM drive system, the NNMFC generates an adaptive control signal which is added to the 2DOF I-PD speed controller output to attain robust model-following characteristics under different operating conditions regardless of parameter variations and load disturbances. A computer simulation is developed to demonstrate the effectiveness of the proposed 200F I-PD NNMF controller. The results confirm that the proposed 2DOF I-PO NNMF speed controller produces rapid, robust performance and accurate response to the reference model regardless of load disturbances or PMSM parameter variations.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.11a
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• pp.313-318
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• 2007

Interior permanent magnet synchronous motor(IPMSM) has become a popular choice in electric vehicle applications, due to their excellent power to weight ratio. This paper proposes maximum torque control of IPMSM drive using adaptive fuzzy neural network controller and artificial neural network(ANN). 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 Adaptive-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 reposes speed control of IPMSM using Adaptive-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 a lied to IPMSM drive system controlled Adaptive-FNN and ANN controller, the operating characteristics controlled by maximum torque control are examined in detail. Also, this paper proposes the analysis results to verify the effectiveness of the Adaptive-FNN and ANN controller.

• The Transactions of the Korean Institute of Power Electronics
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• v.11 no.1
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• pp.7-13
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• 2006

Linear compressors with a free piston driven by a linear motor are widely attention in the cooling apparatus such as refrigerator due to the high efficiency The stroke of piston in the linear compressor driven by LPMSM (Linear Permanent-Magnet Synchronous Motor) can be obtained from Integrating the input voltage and current of LPMSM, but it may be diverged due to dc components in the voltage and current. The strategy to prevent the divergence of stroke using both the high-pass filter and do offset compensation was suggested. The equations for the magnitude and phase of the stroke and also dc offset including the stroke are derived as a function of the cut-off frequency of HPF. The accurate stroke of a piston can be calculated by compensating for dc offset. The performance of the newly developed stroke calculation scheme has been verified by experimentally on a linear compressor drive system, where the control was implemented by a 16-bit DSP.

• The Journal of the Korea institute of electronic communication sciences
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• v.9 no.4
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• pp.527-536
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• 2014

In this paper, the 50kW aerogenerator which is applicable to the microgrid was designed and analyzed by using commercial simulation program Maxwell 2D. Particularly, the suggested PMSG to reduce the cogging torque introduced the offset and skew concept. The suggested optimal value of offset and skew was decided by 2mm and 60 degree of electric angle. The simulation results of the PMSG when load operation condition showed the average harmonic distortion 1.3%, voltage 322.41V, current 94.95A, and iron loss 9.73W, eddy current loss 73.68W, copper loss 3.52kW. The capacity of aerogenerator calculated 61.56kW, and the suggested design process can be applied to higher capacity generator.

• Journal of the Korean housing association
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• v.19 no.2
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• pp.1-10
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• 2008

The purpose of this research is to compare residents' movement and activities in SH apartment in Yangcheon-Gu, Seoul (SH apartment) and PHA apartment in St. Paul, Minnesota (PHA apartment) in order to improve the quality of rental housing environment. This study had surveyed 418 residents of SH apartments in Korea and used the secondary data gathered from 1,462 residents of PHA apartments in the United States. The results of this study are as follows: The criteria of Korean residents in SH apartments when choosing their residences are lower rent payment and shorter waiting time. They seemed to have no other options than public rental housing. On the contrary, American residents in PHA apartment had more option to choose from. Therefore, Korea needs to offer more variety types of residents that can be lead to better satisfaction of low income classes. Most of the SH apartments residents has lived for long-term, in the average of more than 6 years, and wanted to live continually at their current dwelling. PHA residents showed similar tendency. However, long term residency may lead to permanent occupation of the public rental apartment by the same family. Hence, a system which can provide equal residency opportunities to all low-income classes need to be developed. Residents of SH apartment were satisfied with the personal activities but were not satisfied with group activities among residents or regarding resident meetings. However, residents of PHA apartments were more satisfied with their management because there is more in-housing-complex activity programs. Therefore, more activity program for a resident should be developed after analysing programs of different apartments and current conditions in Korea. There were some noticeable divergences among residents, based on their age, term of residence and physical, emotional and mental problem, when evaluating in-housing-complex's programs. Thus, these factors are also need to be considered when planning and examining evaluation about the management of rental apartments.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.9
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• pp.832-838
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• 2011

The shock absorber with magnetic effect is suggested for a lunar lander. The shock absorber consists of a metal tube, a piston rod, and several permanent magnets moved by a piston rod in the tube, and the shock energy can be dispersed and dissipated by magnetic effects such as the magnetic force existed between a metal and magnets and the eddy current effect generated by a relative motion with a conductor and magnets. Besides, the shock-absorbing effect similar to that of a coil spring can be obtained by arranging the magnets in line, which are facing the same polar each other. The device has a very simple structure and is usable in space due to the unnecessariness of any oil or gas. The shock absorber was designed and manufactured for experiments and its spring and damping characteristics were studied by the theoretical, analytical and experimental methods.

• Journal of the Korean institute of surface engineering
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• v.40 no.3
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• pp.125-130
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• 2007

Many fundamental studies have been carried out regarding waste water and hazardous gas treatment technology using the photolysis effect of $TiO_2$. However, photolysis of both organic and organic-inorganic binders immobilizing $TiO_2$ makes permanent use impossible. In this study we manufactured a catalytic electrode by nickel-$TiO_2$ composite plating in order to immobilize $TiO_2$. The surface properties according to the current density changes of cathode and concentration changes of $TiO_2$ powder in nickel plating bath has been analysed with EDX, XRF, SEM, Raman spectrometer etc. The characterization of the catalytic electrode in decomposition of organic compound has been obtained by using UV-Visible spectrophotometer through analysing concentration changes of methyl orange solution containing the catalytic electrode vs. time with projecting UV-light in the solution. The study shows that a catalytic electrode of nickel-$TiO_2$ composite plating with high-efficiency in decompostion of organic compound has been formed under high concentration of $TiO_2$ powder and low current density of cathode.

• Journal of Korean Society of Environmental Engineers
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• v.37 no.5
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• pp.312-323
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• 2015

This paper presents future directions for spent nuclear fuel and high-level radioactive waste management. The successes and failures of siting nuclear waste repository experienced by the United States and other countries are reviewed with the current policy stance. Further, the needs for establishing management policy, considering the high-level radioactive waste produced by the dismantlement, nuclear security concerns, and cost-effectiveness analysis for the total nuclear fuel cycle, are emphasised. Technical discussions are organised into three main topics: interim storage, permanent disposal, and reprocessing. Licensing regimes are also investigated to suggest strategic plans for research and development programmes in the Republic of Korea.

• Journal of Families and Better Life
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• v.24 no.6 s.84
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• pp.177-193
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• 2006

This study analyzes marriage and fertility rates in Korea and makes recommendations for family policy. Based on the 'The Report of Marriage & Divorce Statistics in 2005' and data from the Korea Statistical Information System (KOSIS) of the National Statistics Organization, the trends, reasons for marriage rates changes, and future expectations were critically reviewed. In addition, the relationship between marriage and fertility rates was analyzed. The principle characteristics of marriage rates are as follows: 1) the M-shape of the longitudinal crude marriage rates; 2) the increased age of individuals entering their the first marriage; 3) the increase in remarriage rates; 4) the changes in the patterns of remarriage; 5) the increased in the age at which individuals remarry and; 6) the increase in marriage to non-Koreans. The marriage and fertility rates changes are a permanent normative shift because of 1) later marriage because of women's increased education and labor force participation 2) rational choices about birth control 3) reduced population because of the aging of baby boomers 4) structural changes in the marriage market and 5) egalitarian changes in women's attitudes toward marriage and family. The recommendations for future family policy were as follows: 1) the need for a realistic, long-term family policy because the current marriage patterns will continue; 2) the need to develop new statistics such as fertility rates that are based on marriage cohort or birth cohort because family behavior is a mixture of personal, social and political responses; 3) the need for impact analysis of current family policy about increasing fertility rates; 4) the need for a new family perspective that encompasses diverse marriage and family patterns; 5) the need to focus on men's role in families because of women's changing roles and family interaction patterns and; 6) the need for preventive family policies such as family life education.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.5
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• pp.94-105
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• 2010

To detect faults in an inverter-fed permanent magnet synchronous motor (PMSM) drive under the circumstance having faults in a stator winding and inverter switch, an on-line basis fault detecting scheme during operation is presented. The proposed scheme is achieved by monitoring the second-order harmonic component in q-axis current and the fault is detected by comparing these components with those in normal conditions. The linear interpolation method is employed to determine the harmonic data in normal operating conditions. As soon as the fault is detected, the operating mode is changed to identify a fault type using the phase current waveform. To verify the effectiveness of the proposed fault detecting scheme, a test motor to allow inter-turn short in the stator winding has been built. The entire control algorithm is implemented using DSP TMS320F28335. Without requiring an additional hardware, the fault can be effectively detected by the proposed scheme during operation so long as the steady-state condition is satisfied.