• Ocean and Polar Research
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• v.25 no.4
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• pp.437-446
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• 2003

Field measurements of directional waves were carried out during the summer of 2002 at two coastal sites in water of finite depth. A couple of general purpose instruments were used employing acoustic Doppler technology. The aim of the study was to investigate the spatial behavior of the directional movement of waves as they come ashore. In total,74 tests were carried out during which sea states of low to moderate intensity were recorded. A great number of these runs displayed bimodal characteristics of the spreading function at high frequencies. It was found that in general, the frequency-integrated directional width tends to broaden as the water shoals and when refraction effects are negligible. This is attributed to wave-wave interactions that become pronounced in shallow water. The same directional width showed, also, a tendency to increase with increasing peak frequency of the sea state spectrum. The behavior of the kurtosis of the spreading function was also examined. It was found that for higher frequencies this index tends to increase in wave spectra above a certain sea severity threshold.

• The Transactions of the Korean Institute of Electrical Engineers B
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• v.55 no.2
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• pp.76-82
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• 2006

This paper investigates the magnetic field behavior and its iron losses in the stator core using electrical steels. The analysis model is a brushless motor with the permanent magnet. The elliptical rotating and alternating flux distributions with non-sinusoidal waveform are obtained by Finite Element Method and then their harmonic components are extracted. Based on these results, the local iron losses in the stator core caused by the harmonic flux are calculated. And then this paper explains the relation between flux waveform and iron loss produced in each part of the stator core. Furthermore, the iron loss at no load condition is measured and compared with the analysis results.

• Proceedings of the KIEE Conference
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• 2002.11d
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• pp.46-48
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• 2002

This paper formulates the principle of the permanent magnetic actuator (PMA) and its dynamic characteristic calculation. Some results of the calculation and analysis of the dynamic curves are presented. Due to its great advantages, PMA that presented recently drew great attention from engineers all over the world. We present the magnetic field and actuator using finite element method associated to parameter calculating the displacement of the moving parts and the supplying current when the actuator is DC voltage supplied or capacitor supplied. In this paper, We will do compare of dynamic behavior between DC voltage supplied and capacitor discharge supplied.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.4 no.4
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• pp.25-32
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• 1995

This study is to inspect the influence of the initial residual stress on fatigue crack growth behavior after the distribution of the initial residual stress is measured when the crack is growing from the compressive residual stress field. Also, the tensile residual stress field. Also, the influence of the variation of residual stress distribution on fatigue crack growth behavior at the crack tip is studied when the initial crack occurs on weld metal, bead interface and HAZ (Heat Affected Zone), respectively. For this purpose, CT-type specimen that crack parallel to the welding bead were manufactured by butt welding on the Al. Alloy 1100-O plate.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.05a
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• pp.489-494
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• 2002

This paper presents hydraulic model which can capture the hysteric damping force behavior of ER damper. A flow mode rue ER damper is manufactured, and its field-dependent damping forces are measured. Newly proposed hydraulic model which derived from physical hydro-mechanical parameters of ER damper are conventional Bingham model are investigated to represent the field-dependent damping force characteristics of ER damper. After principal parameters of two models are estimated from the measured damping forces data, the force vs velocity hysteresis cycles are then reconstructed. The results show that the proposed hydraulic model can capture the hysteresis behavior of ER damper accurately.

• Journal of the Korean Society for Precision Engineering
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• v.18 no.2
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• pp.146-151
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• 2001

The effects of slant interface in the hybrid specimen on the dynamic crack propagation behavior have been investigated using dynamic photoelasticity. The dynamic photoelasticity with the aid of Cranz-Shardin type high speed camera system is utilized to record the dynamic stress field around the dynamically propagating inclined interface crack tip in the three point bending specimens. The dynamic load is applied by a hammer dropped from 0.08m high without initial velocity. The dynamic crack propagation velocities and dynamic stresses field around the interface crack tips are investigated. Theoretical dynamic isochromatic fringe loops are compared with the experimental reults. It is interesting to note that the crack propagating velocity becomes comparable to the Rayleigh wave speed of the soft material of a specimen when slant angle decreases.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.543-546
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• 2004

Nutrients behavior were investigated at a paddy fields area(Soro-ri) with large-scaled plots on loam soil during irrigation seasons of $2001\~2003$. The average concentration of TN, TDN and TDP in drainage water was higher than that in irrigation water. On the other hand, the average concentration TP in irrigation water was higher than in drainage water. The ratio of TDN to TN accounted (or over $90\%$ and the ratio of TDP to TP accounted for $50\~70\%$. Especially the ratio of TDP to TP in drainage water was higher than that in irrigation water, suggesting that much of particulate component was reduced due to sedimentation and adsorption in paddy fields plots. Overall, particulate phosphorus usually account for 44 to $77\%$ of tile total phosphorus during storm events.

• Journal of the Korean Ceramic Society
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• v.46 no.2
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• pp.219-223
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• 2009

Effects of MgO or $R_2O_3$(R:Dy, Ho, Yb) on the capacitance aging behavior of multilayer ceramic capacitors (MLCCs) based on $BaTiO_3$ dielectrics under DC electrical fields has been studied. At a DC field of 1 $V{/\mu}m$, the capacitance of MLCC specimens dropped immediately in a very short period (<10 s, the first stage) and then decreased continuously with time (the second stage). Mn doping significantly increased the aging rate in the second stage. The addition of MgO or $R_2O_3$ notably decreased the second stage aging rate of Mn-doped specimens. Yb doping gives rise to the lowest aging rate in the second stage, which is due to the larger population of defect dipoles associated with oxygen vacancies.

• Journal of the Korea institute for structural maintenance and inspection
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• v.6 no.2
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• pp.203-210
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• 2002

In these days, High-strength steel prevails throughout the construction fields for the benefit of structural and economical aspects. But high-strength steel is used by the simple calculation of flexural capacities for the purpose of reducing flexural reinforcement. So, this paper is mainly focused on the shear behavior of high-strength steel reinforced concrete beams without stirrups comparing with normal-strength steel reinforced concrete beams. Specimens were made and tested with the experimental parameters, such as steel yield strength, reinforcement ratios and minimum shear reinforcement. The main result was that not only area but also the yield strength of flexural reinforcement should be considered to predict the shear capacities of concrete beams. In addition, the experimental results were simulated by modified compression field theory analysis program, RESPONSE 2000. A good agreement was achieved between the test results and program analyses.

• Child Studies in Asia-Pacific Contexts
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• v.2 no.1
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• pp.1-10
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• 2012

The present study, based on Tiffany Field's model of violence and intimacy as well as other previous research, examines the relationship between parents' physical affection and their child's aggressive behavior. One hundred seventy-five mothers and 124 fathers of Japanese preschoolers answered a questionnaire that included a parental physical affection scale developed for this study. Children's aggressive behaviors were rated by their teachers on the hostile-aggressive subscale of the Preschool Behavior Questionnaire. Consistent with Field's model and previous studies, the results of logistic regression analyses indicated that children who received more physical affection from mothers or fathers during daily parenting were less likely to be aggressive at preschool. When the mother's and the father's physical affection scores were simultaneously entered in the equation, only the father's score was significant. Implications and limitations of the research are discussed.