• Research in Community and Public Health Nursing
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• v.32 no.3
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• pp.254-267
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• 2021

Purpose: The purpose of this study was to identify the effects of brain-wave biofeedback training nursing intervention (NFT) upon enhancing self-regulation response in adolescence with emotional behavior problems in school. Methods: A quasi-experimental design was conducted. The participants were assigned to the experimental group (n=24) or the control group (n=24). The experimental group additionally received NFT. The NFT was conducted 10 sessions for 30 minutes per session with the band reward and inhibit training which matched their Quantitative Electroencephalography (QEEG), participant's demand and chief complaint. Data were collected with QEEG and heart rate variability (HRV) in physiological response, self-efficacy in cognitive response, depression in emotional response, impulsivity and delay gratification in behavioral response of self-regulation. Results: The general characteristics and the pre-test scores of two groups were all homogeneous. The experimental group was reported to be significantly higher in QEEG homeostasis, HRV homeostasis, self-efficacy, and delay gratification than the control group. The experimental group was reported to be significantly lower in depression and impulsivity. Conclusion: The results indicate that NFT using brain cognitive neuroscience approach is effective in enhancing self-regulation response. Therefore, this nursing intervention using brain cognitive neuroscience approach can be applied as an effective self-regulation nursing intervention for adolescents with emotional behavior problems in communities for adaptive life.

• Journal of the Society of Naval Architects of Korea
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• v.46 no.5
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• pp.488-497
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• 2009

The freak wave, also known as New-Year-Wave in the north Atlantic, is relatively large and spontaneous ocean surface wave that can sink even large ships and destroy maritime structures. To understand oceanic conditions that develop freak waves, we simulated and generated two versions of scale-downed waves (1:64 and 1:42) in a numerical wave tank and compared the results with the experiment in wave flume. Both of the breaking and non-breaking waves were generated in the simulation. The numerical simulation was implemented based on the finite volume method and a genetic optimization algorithm. Random values were assigned as the initial values for the parameter in the control function, which produced signals representing the motion of wave-maker. The same signal obtained from the optimization process was used for both of the simulation and the experiment. By varying the object function and restrictions of the simulation, a best profile of design wave was selected based on the characteristics, height and period of simulated waves. Results showed that the simulation and experiment with the scale of 1:42 agreed better with freak waves in the natural condition. The presented simulation method will contribute to saving the time and cost for conducting subsequent response analyses of motion under freak waves in the course of the model test for ship and maritime structure.

• International Journal of Naval Architecture and Ocean Engineering
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• v.5 no.3
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• pp.333-347
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• 2013

The present study numerically models the interaction between a regular wave and the roll motion of a rectangular floating structure. In order to simulate two-dimensional incompressible viscous two-phase flow in a numerical wave tank with the rectangular floating structure, the present study used the volume of fluid method based on the finite volume method. The sliding mesh technique is adopted to handle the motion of the rectangular floating structure induced by fluid-structure interaction. The effect of the wave period on the flow, roll motion and forces acting on the structure is examined by considering three different wave periods. The time variations of the wave height and the roll motion of the rectangular structure are in good agreement with experimental results for all wave periods. The present response amplitude operator is in good agreement with experimental results with the linear potential theory. The present numerical results effectively represent the entire process of vortex generation and evolution described by the experimental results. The longer wave period showed a different mechanism of the vortex evolution near each bottom corner of the structure compared to cases of shorter wave periods. In addition, the x-directional and z-directional forces acting on the structure are analyzed.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.1
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• pp.182-189
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• 2012

This study suggests a dynamic design process for deciding properly design parameters of a mass-spring type Wave Energy Converter (WEC) to achieve sufficient energy conversion from wave to power generator. The WEC mechanism, in this research, consists of a rigid sprung body, a platform, suspension springs and dampers. The rigid sprung body is supported on the platform via springs and dampers and vibrates translationally in the heave direction under wave excitation. At last the resulting heave motion of the sprung body is transmitted to rotating motion of the electric generator by rack and pinion, and transmission gears. For the purpose of vibration analysis, the WEC mechanism has been simply modelled as a mass-spring-damper system under harmonic base excitation. Its maximum displacement transmissibility and steady state response can be determined by using elementary vibration theory if the harmonic ocean wave data were provided. With the vibration analysis results, the suggested dynamic design process of WEC can determine all the design parameters of the WEC mechanism, such as sprung body mass, suspension spring constant, and damping coefficient that can give sufficient relative displacement transmissibility and the associated inertia moment to drive the electric generator and transmission gears.

• Nuclear Engineering and Technology
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• v.53 no.6
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• pp.1846-1857
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• 2021

Ultrasonic nondestructive testing is important for monitoring the structural integrity of dissimilar metal welds (DMWs) in pressure vessels and piping in nuclear power plants. However, there is a low probability of crack detection via inspection of DMWs using ultrasonic waves because the grain structures (grain orientations) of the weld area cause distortion and splitting of ultrasonic beams propagating in anisotropic media. To overcome this issue, the grain orientation should be known, and a precise ultrasonic wave simulation technique in anisotropic media is required to model the distortion and splitting of the waves accurately. In this study, a method for nondestructive prediction of the DMW grain orientations is presented for accurate simulation of ultrasonic wave propagation behavior in the weld area. The ultrasonic wave propagation behavior in anisotropic media is simulated via finite-element analysis when ultrasonic waves propagate in a transversely isotropic material. In addition, a methodology to predict the DMW grain orientation is proposed that employs a simulation technique for ultrasonic wave propagation behavior calculation and an optimization technique. The simulated ultrasonic wave behaviors with the grain orientations predicted via the proposed method demonstrate its usefulness. Moreover, the method can be used to determine the focal law in DMWs.

• Smart Structures and Systems
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• v.24 no.4
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• pp.525-539
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• 2019

In this study, vibration characteristics of a gravity-based caisson-foundation breakwater system are investigated for ambient and geometric parameters such as various waves, sea levels, and foundation conditions. To achieve the objective, following approaches are implemented. Firstly, operational modal analysis methods are selected to identify vibration modes from output-only dynamic responses. Secondly, a finite element model of an existing caisson-foundation breakwater system is established by using a structural analysis program, ANSYS. Thirdly, forced vibration analyses are performed on the caisson-foundation system for two types of external forces such as controlled impacts and wave-induced dynamic pressures. For the ideal impact, the wave force is converted to a triangular impulse function. For the wave flow, the wave pressure acting on the system is obtained from wave field analysis. Fourthly, vibration modes of the caisson-foundation system are identified from the forced vibration responses by combined use of the operational modal analysis methods. Finally, vibration characteristics of the caisson-foundation system are investigated under various waves, sea levels, and foundations. Relative effects of foundation conditions on vibration characteristics are distinguished from that induced by waves and sea levels.

• Journal of Korean Association for Spatial Structures
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• v.15 no.2
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• pp.113-120
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• 2015

This study investigate the dynamic response changes of rib dome structure according to property changes of Substructure. Eigenvalue analysis is conducted in first natural frequency of rib dome versus substructure and searched in the dominant mode of horizontal and vertical direction. Resonance frequency by each first natural frequency of the rib dome structure, substructure and total structure is applied for a seismic wave. That is analyzed about maximum displacement response ratio and maximum acceleration response ratio.

• Proceedings of KOSOMES biannual meeting
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• 2003.05a
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• pp.173-178
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• 2003

• The Bulletin of The Korean Astronomical Society
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• v.32 no.1
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• pp.49.1-49.1
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• 2007

• Proceedings of the Korean Vacuum Society Conference
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• 2006.08a
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• pp.60-60
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• 2006