• International Journal of Precision Engineering and Manufacturing
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• v.3 no.1
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• pp.20-25
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• 2002

Electrical damages to critical parts in rotating machinery have caused many machinery failures and hours of costly downtime. The problem of shaft currents generated in non-electrical machines has puzzled both users and manufacturers of these machines. The main solution for preventing electromagnetic type damage is to demagnetize all of the machinery parts, however this is costly and time consuming. Therefore a thorough investigation into the causes and physical characteristics of electromagnetic shaft currents is needed. In this paper, the self excitation theory was developed far a simple model, an axial flux Faraday disk machine surrounded by a long solenoid. Experimental tests were conducted to investigate the physical characteristics on an electromagnetic self excitation rig. The theory showed that the directions of both the shaft rotation and the coil turns should be identical if self excitation is to occur. From the tests, the electromagnetic type shaft current had both AC and DC components occurred at all vibration frequencies. This could point to a way to detect small instabilities or natural frequency locations by monitoring shaft currents.

• International journal of advanced smart convergence
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• v.9 no.2
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• pp.58-67
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• 2020

In this paper, we propose a data-driven-based beam selection scheme for massive multiple-input and multiple-output (MIMO) systems in ultra-dense networks (UDN), which is capable of addressing the problem of high computational cost of conventional coordinated beamforming approaches. We consider highly dense small-cell scenarios with more small cells than mobile stations, in the millimetre-wave band. The analog beam selection for hybrid beamforming is a key issue in realizing millimetre-wave UDN MIMO systems. To reduce the computation complexity for the analog beam selection, in this paper, two deep neural network models are used. The channel samples, channel gains, and radio frequency beamforming vectors between the access points and mobile stations are collected at the central/cloud unit that is connected to all the small-cell access points, and are used to train the networks. The proposed machine-learning-based scheme provides an approach for the effective implementation of massive MIMO system in UDN environment.

• Korean Journal of Child Studies
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• v.28 no.2
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• pp.71-89
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• 2007

The subjects in this study of parenting attitudes, children's behavior problems and attention ability were 111 5-year-old children and their parents. Data was analyzed by mean, frequency, percent, three-way ANOVA, and Pearson's correlation. Results showed that behavior problems and attention ability of children varied by the parenting attitude of mothers and fathers. Behavior problems of boys were higher than girls, and boys' attention abilities were lower than girls.' Interaction effects were found between parenting attitudes and gender in children's behavior problems and attention ability : fathers' autonomy correlated negatively with boys' behavior problems (r=-.47), task processing speed (r=-.37), and attention inconsistency (r=-.36). Children's behavioral problems correlated positively with attention inconsistency (r=.28).

• Transactions on Control, Automation and Systems Engineering
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• v.4 no.4
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• pp.319-323
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• 2002

In this paper, we consider the track-following control problem in the optical data storage systems in the presence of the eccentricity. The eccentricity results in the radial deviation of the objective lens so that it degrades the reliability of the data decoding system. To cope with the eccentricity, an adaptive disturbance compensation technique is newly proposed in the time domain based on a disturbance observer of reduced order, which effectively estimates the low frequency components of the disturbance. The proposed compensator is simply added to the conventional feedback control. The error dynamics of the observer and the sensitivity analysis are given to illustrate the effectiveness of the proposed approach. Finally, through experiments in an optical storage system, the feasibility of the proposed approach is verified.

• Proceedings of the IEEK Conference
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• 2000.06e
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• pp.113-116
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• 2000

In this paper presents the portable wireless ECG data detection and diagnosis system based on discreet wavelet transform. An algorithm based on wavelet transform suitable for real time implementation has been developed in order to detect ECG characteristics. In particular, QRS complex, S and T waves may be distinguished form noise, baseline drift or artifacts. Proposed telemetry system that a transmitting media using radio frequency(RF) for the middle range measurement of the physiological signals and receiving media using optical for electromagnetic interference problem. A standard hi-directional serial communication interface between the telemetry system and a personal computer or laptop, allows read-time controlling, diagnosing and monitoring of system. A portable telemetry system within a size. of 65${\times}$125${\times}$45mm consists of three parts: a digital signal processing part for physiological signal detect or diagnose, RF transmitter for data transfer and a optical receiver for command receive. Advantages of proposed telemetry system is wireless middle range(50m) FM transmission, reduce electromagnetic interference to a minimum. which enables a comfortable diagnosis system at home.

• Proceedings of the IEEK Conference
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• 2003.07e
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• pp.2343-2346
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• 2003

The spatial resolution of multispectral images can be improved by merging them with higher resolution image data. A fundamental problem frequently occurred in existing fusion processes, is the distortion of spectral information. This paper presents a spatially adaptive image fusion algorithm which produces visually natural images and retains the quality of local spectral information as well. High frequency information of the high resolution image to be inserted to the resampled multispectral images is controlled by adaptive gains to incorporate the difference of local spectral characteristics between the high and the low resolution images into the fusion. Each gain is estimated to minimize the l$_2$-norm of the error between the original and the estimated pixel values defined in a spatially adaptive window of which the weight are proportional to the spectral correlation measurements of the corresponding regions. This method is applied to a set of co-registered Landsat7 ETM＋ panchromatic and multispectral image data.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.58 no.12
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• pp.2359-2369
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• 2009

The study on the multi-level inverter has been increasingly progressing to reduce the switching loss and improve the THD of output current in photovoltaic inverter. Recently, the main topics of multi-level inverter are to reduce the number of devices maintaining the power quality. Therefore, the novel topology was proposed for these problem which is composed of the isolated H-bridge multi-level inverter using the three phase low frequency transformer. The proposed multi-level inverter may not be need for a independent DC power, diode and capacitor. Specially, It has a advantage in generating high voltage source. The proposed approach is verified through simulation and experiment.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2000.11a
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• pp.70-76
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• 2000

In the charge system, a contact type-convenient-charging method is insufficient because of the contact failure around moist environment and troublesome question to put in and pull out. For the solution of this problem, an electromagnetically coupled non-contact charger for the rechargeable cell is proposed using ZVS multi-resonant forward converter with synchronous rectifier. In this paper coupling coefficient(k), leaking inductance, coupling inductance and resonant frequency are observed for the air gap. By using the observed value, this circuit is designed and implemented. This proposed circuit is simulated by the PSPICE and experimented. The stress of a main switch and the output power are measured.

• Journal of Family Resource Management and Policy Review
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• v.6 no.2
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• pp.1-14
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• 2002

The purpose of this study was examine and clarify the recognition according to gender of sexual harassment in the office. The samples were consisted of 250 employees in a seoul headquarter and 13 branches of S bank. the data were analyzed using percentage, frequency, mean, 1-test, F-test and ANOVA. The results of this study were as follows; 1) female workers recognized sexual harassment as severe problem, but male workers as minor and trivial things. 2) workers recognized the cause of sexual harassment as female low position in the office and sexual distinction 3) workers recognized sexual harassment type as visual, verbal and physical harassment. 4) workers recognized the main assaulters of sexual harassment as male senior workers and co-workers. 5) worker recognized place of harassment as times of workers' dining together. 6) worker recognized the victim of sexual harassment was apt to experience anger, hurt of self-respect, shame and embarrassment. 7) female workers recognized necessity of sexual education but male workers none of it.

• Journal of the Korean Home Economics Association
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• v.41 no.11
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• pp.171-187
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• 2003

The purpose of this study was to measure the effects of self-growth group counseling program for children in a group home. The results of this study are as follows. First, the self-growth group counseling program was effective to improve self esteem. The most significant increases were seen in the global self-esteem and school-academic self-esteem. Second, the group cohesion and participation frequency of the program were improved, as the session was progressed. Third, as the changes of individual, the understanding and acceptance of oneself and the others are improved. So, impulsivity and aggression became lower, and problem behavior was less.