• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2013.10a
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• pp.149-150
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• 2013

Recently, various types of perforated breakwaters are being constructed for protecting offshore storm waves. In general, perforated breakwaters have wave chambers with perforated walls at seaside. Purposes of the wave chambers are to reduce wave reflections and maximum wave forces acting on the breakwater. Impact wave forces due to wave breaking can attack to the perforated wall directly, so the effects have to be considered in the design of the perforated wall carefully. Using resonance channels for wave energy dissipation, a new concept perforated breakwater is proposed, which is free from impact loads. Numerical simulation was made for wave reflection characteristics of the breakwater with respect to major design parameters. Numerical analysis was carried out using the Galerkin's FE model based on the linear potential theory considering energy dissipation on the perforated plate. Variations of wave reflection was investigated according to perforated ratios of perforated plate.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.10a
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• pp.303-308
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• 2003

In this paper, wave numerical modeling was experimented for the analysis of impact factors for the wave transmission as the incident wave and topographic conditions in the narrow channel sea. Recently, Although the results of many researcher for the wave modelling, numerical equations have limited to simulation of wave transformation effects. Despite of thispresent problems, the models was used to design the coastal structures in barrow channel sites. Finally, this paper estimated the wave model(mild slope eq. model) as the analysis of the wave energy transmission according to changing of impact factors(width of channel, bottom slope in channel, incident wave angle, wave period). As the results of numerical experiment, the major impact factors which influence to wave energy transmission were the width of channel and incident wave direction. But in the case that the width of channel is larger than 3L(L=Length of wave), the reduction of wave energy was small.

• Journal of Ocean Engineering and Technology
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• v.34 no.4
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• pp.245-252
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• 2020

Wave run-up is an important phenomenon that should be considered in ocean structure design. In this study, the wave run-up of a surface-piercing circular cylinder was calculated in the time domain using the three-dimensional linear and fully nonlinear numerical wave tank (NWT) techniques. The NWT was based on the boundary element method and the mixed Eulerian and Lagrangian method. Stokes second-order waves were applied to evaluate the effect of the nonlinear waves on wave run-up, and an artificial damping zone was adopted to reduce the amount of reflected and re-reflected waves from the sidewall of the NWT. Parametric studies were conducted to determine the effect of wavelength, wave steepness, and the draft of the cylinder on the wave run-up of the cylinder. The maximum wave run-up value occurred at 0°, which was in front of the cylinder, and the minimum value occurred near the circumferential angle of 135°. As the diffraction parameter increased, the wave run-up increased up to 1.7 times the wave height. Furthermore, the wave run-up was 4% higher than the linear wave when the wave steepness was 1/35. In particular, the crest height of the wave run-up increased by 8%.

• Journal of Ocean Engineering and Technology
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• v.30 no.4
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• pp.235-242
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• 2016

In general, ship hull form design is carried out in two stages. In the first stage, the longitudinal variation of the sectional area curves is adapted from a similar mother ship to determine the volume distribution in ships. At this design stage, the initial design conditions of displacement, longitudinal center of buoyancy, etc. are satisfied and the global hydrodynamic properties of the structure are optimized. The second stage includes the local designing of the sectional forms. Sectional forms are related to the local pressure resistance in the fore- and aft-body shapes, cargo boundaries, interaction between the hull and propeller, etc. These relationships indicate that the hull sections need to be optimized in order to minimize the local resistance. The volumetric balanced (VOB) variation of ship hull forms has been suggested by Kim (2013) as a generalized, systematic variation method for determining the sectional area curves in hull form design. This method is characterized by form parameters and is based on an optimization technique. This paper emphasizes on an extensional function of the VOB considering a geometrical wave profile. We select a container ship and an LNG carrier to demonstrate the applicability of the proposed technique. Through analysis, we confirm that the VOB method, considering the geometrical wave profile, can be used as an efficient tool in the hull form design for ships.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.15 no.8
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• pp.801-808
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• 2004

In this paper, we proposed the grating parallel plate waveguide structure for converting a linearly polarized wave to a circularly polarized wave. For the design of the polarizer, the moment method and Floquet's theorem are applied under two assumptions that the incident wave is a plane wave and the structure is infinitely periodic. In order for the more precise design, we performed the near-field analysis for the finite polarizer structure using MATLAB. By comparing with the measured results obtained by the near-field arrangement, we verified the correctness of our near-field analysis. By taking the ideal assumptions considered in the initial design procedure into account, newly designed modified dimensions for the polarizer was suggested which give improved performance.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.2
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• pp.146-151
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• 2016

This study concentrates on the design of floater for 15kW-class wave energy converter that extracts the ocean energy by oscillating vertically along the wave motion. The floater connects to a arm structure that connects to a hydraulic cylinder, which drives a hydraulic generator. The study mainly focuses on the structural analysis of the floater. Previous studies have been conducted using a miniature model; however, this study focuses on the size selection of the floater for a full scale model. Static structural analysis is conducted using fine numerical grids. Due to the complexity of the whole model, it is analyzed as a separate component. There are several load cases for each floater size, and they are analyzed thoroughly for stress (von-mises, shear, and normal) and deformation. The initial design was conducted by scaling up from the miniature model of the previous study, and the final design has been redesigned by changing the thickness and internal support structure shape.

• The Transactions of the Korean Institute of Electrical Engineers P
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• v.62 no.1
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• pp.1-5
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• 2013

The aim of this study is to research maximum harvesting energy by the optimal input wave condition. The voltage characteristics of the PZT bimorph were investigated in terms of the sine wave, triangle wave and square wave according to frequency range 0~70Hz. It was found that the square wave compared with a triangular wave or square wave was showed the higher output energy. PZT bimorph was mechanically vibrated by solenoid coil experiments, which revealed two voltage peak mode according to frequency. Maximum voltage at second vibration frequency 28Hz demonstrated that the generated DC voltage was proportional to the tip displacement of the bimorph and the phase difference between the input frequency and bimorph vibration frequency was 90 degree. It was expected that optimized design to harvest a much higher energy level from lower frequency vibrations.

• Journal of Korea Multimedia Society
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• v.20 no.9
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• pp.1519-1526
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• 2017

The existing DSRC(Dedicated Short Range Communication) scheme has a limitation in providing various services through short-range wireless communication. Therefore, it is necessary to develop an intelligent WAVE/DSRC hybrid wireless platform that can improve data transmission speed and extend the effective communication range. This paper introduces WAVE/DSRC integrated platform technology using WAVE(Wireless Access in Vehicle Environments) to overcome the disadvantages of DSRC. First, the desinged software configuration of the WAVE/DSRC integrated platform is described. Then each task operation scheme and WAVE software design are described. By applying the WAVE/DSRC integrated platform, we can compensate the shortcomings of DSRC. It can provide more accurate and reliable services.

• Journal of the Korean Society of Costume
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• v.56 no.4 s.103
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• pp.124-133
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• 2006

Human hair could be damaged by various physicochemical conditions and treatment. Permanent and decoloring treatment were the most serious factor on hair damage. The new permanent wave lotion containing Permeation enhancers such as Cremophor EL, Transcutol and propylene glycol based on cysteine permanent wave lotion were prepared. Efficiency of permanent wave and hair damage following pH of permanent wave lotion and addition of permeation enhancer were investigated. PH of solution, wave efficiency, loss of protein from hair, morphology of hair by SEM and solubility of alkaline solution were evaluated. The addition of Cremophor EL and Transcutol with ethanol increased permanent wave efficacy and decreased hair damage effectively. They diminished permanent wave lotion's pH and augmented permanent wave lotion's penetration compare to cysteine permanent wave lotion. new permanent wave lotion containing permeation enhancers such as Cremophor EL could be a good candidate for a new permanent wave lotion.

• Journal of the Society of Naval Architects of Korea
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• v.58 no.2
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• pp.112-120
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• 2021

The novel wave generating system of a wave flume has been devised by utilizing the analytic solution of wave board motion in idealized two dimensional space. The arbitrary oscillation motion of submerged wave board segment has been defined by sinusoidal motion of upper and lower end of the wave board. The analytic solution of the wave board motion has been represented by the solution of board motion due to flap motion and swing motion. Arbitrary oscillation of the board could be specified by determining amplitude, frequency, and the phase lag. A novel hybrid wave generator could be operated not only in piston motion but also in flap or swing motion by selection of control parameter. The wave generator has unique motion enhancing ability by appending flap motion or swing motion to piston motion in wave generation. In addition the hybrid wave generator has advantages in generating high quality wave spectrum of irregular wave in simulating real sea condition.