• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.2 no.2
• /
• pp.96-103
• /
• 1990

A local Iribarren number is suggested for the universal use of breaker type classification, which relates the bed slope to the wave steepness, both being given from the breaking point. The existing Iribarren number uses the wave length at an offshore point, while the local Iribarren number uses the wave length at the breaking point so that it can imply any influences due to current interaction and diffraction. The modified form of Miche's breaking criterion includes 고 breaking parameter which may be related to the local Iribarren number. Using the modifiedform of Miche's criterion with the local Iribarren number, the inclusion of Doppler effect seems to describe well the wave breaking mechanism in a current-interacted flow on a sloping beach without any additional effects implemented.

• Journal of Ocean Engineering and Technology
• /
• v.21 no.1 s.74
• /
• pp.18-24
• /
• 2007

When the wind blows strong, most waves are breaking at sea. Breaking waves occur by exceeding the limitation of wave steepness (wave height/wave length = 1/7). Because a wave of single angular frequency couldn't generate the breaking phenomena at a two-dimensional ocean engineering basin, the breaking wave can be generated by the superposition of waves with various angular frequencies based on dispersion relation. This study investigates the particle kinematics in the breaking wave and the magnitude of the breaking wave exciting force at the breaking point and breaking region. We compare the regular wave load in a regular wave, which has same specifications (wave height, period and length), with the breaking waveload. Also, the experimental results of wave exciting force and particle velocity are investigated, by comparison with the analytic results using the potential theory.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
• /
• 2004.11a
• /
• pp.96-101
• /
• 2004

When the wind blows hard, most waves are breaking in sea. Breaking waves occur, exceeding limitation of wave steepness(wave height/wave length=l/7). Because a wave of single angular frequency couldn't generate the breaking phenomena at two dimensional ocean engineering basin, the breaking wave can be generated by the superposition of waves with various angular frequencies. We research how are the particle kinematics in the breaking wave and the magnitude of the breaking wave exciting force. We compare the force in a regular wave which has same specifications(wave height, period and length) as the breaking wave. Also the experimental results of wave exciting force and particle velocity are investigated by comparison on the analytic results using the potential theory.

• The Transactions of The Korean Institute of Electrical Engineers
• /
• v.59 no.10
• /
• pp.1816-1822
• /
• 2010

In this research TPS (Train Performance Simulation) blocks are designed using Simulink and applied to generate speed profiles for energy-efficient train operation. With a train operation mode of maximum powering, coasting, and maximum breaking, a breaking point is calculated from forward-backward running profiles. Then, GA (Genetic Algorithm) is used to solve a running time constraint, and a coasting point is produced from the searching process of GA. With the breaking point and the coasting point a speed profile is plotted. Train performance under a speed limit and gradient variations is simulated and resultant speed profiles are analyzed.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.4 no.3
• /
• pp.178-186
• /
• 1992

An experimental study of deep-water breaking waves are performed by superposition of different wave frequencies, faster waves overtaking slow waves at a certain location. Large spilling and plunging breaking waves are generated near the expected breaking location. Wave steepness in spilling and plunging breakers significantly increases as the breaking point is approached and then decreases after breaking. Larger growth rate of the wave steepness in vigorous plunging breaking is observed. The fundamental wave frequencies in a wave group are dominant through the wave evolution, even in an intense plunging breaking event.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.31 no.4A
• /
• pp.303-309
• /
• 2011

Laminated rubber bearing is the most commonly used device for seismic base isolation of bridge structures. It is important to know performance and behavior characteristics of the laminated rubber bearings. The main evaluation factors of the rubber bearing are classified as compressive, shear and tensile behavior characteristics. The reference data of compressive and shear characteristics are rich, but the reference data of tensile characteristics is scarce. In this study, tensile test results of the rubber bearing with variation of shape factor and shear deformation are investigated for mechanical property. When tensile deformation in normal condition is increasing, tensile cycle behavior curve becomes non-linear and tensile breaking point is 300%. On the other hand, tensile breaking point is shear deformation condition is about 40%. Furthermore, when shape factor is lower, tensile breaking point is decrease. This results mean that tensile breaking point is decreased in triaxial tensile deformation because of cracks caused by internal void of the rubber bearings. This experimental data can be used as the reference data of tensile characteristics for designing seismic isolation of structures.

• Journal of the Korean Society for Nondestructive Testing
• /
• v.27 no.3
• /
• pp.246-254
• /
• 2007

The scanning laser source (SLS) technique is a promising new laser ultrasonic tool for the detection of small surface-breaking defects. The SLS approach is based on monitoring the changes in laser-generated ultrasound as a laser source is scanned over a defect. Changes in amplitude and frequency content are observed for ultrasound generated by the laser over uniform and defective areas. The SLS technique uses a point or a short line-focused high-power laser beam which is swept across the test specimen surface and passes over surface-breaking or subsurface flaws. The ultrasonic signal that arrives at the Rayleigh wave speed is monitored as the SLS is scanned. It is found that the amplitude and frequency of the measured ultrasonic signal have specific variations when the laser source approaches, passes over and moves behind the defect. In this paper, the setup for SLS experiments with full B-scan capability is described and SLS signatures from small surface-breaking and subsurface flaws are discussed using a point or short line focused laser source.

• Horticultural Science & Technology
• /
• v.31 no.6
• /
• pp.666-676
• /
• 2013

The study was carried out to examine the initial point of dormancy, breaking time of internal dormancy, and to find out the accumulated hours of low temperature (under $7.2^{\circ}C$ from $0.0^{\circ}C$ to $7.2^{\circ}C$) for bud-breaking. Over-all, the chilling requirement for breaking of internal dormancy in the commercial apple cultivars ('Fuji' and 'Tsugaru') and apple cultivars bred in Korea ('Hongro', 'Sunhong', 'Honggeum', 'Hongan', 'Hongso', 'Gamhong', 'Summer dream') at the Gunwi region for 4 years (from 2009 to 2012) was investigated. Also, the breaking time of internal dormancy in the field at the Gunwi region and the breaking time of dormancy if air temperature of Gunwi region rises $4^{\circ}C$ higher than the current one were investigated using the same data. The initial point of dormancy was set at the time when the lateral bud breaking did not occurred (when heading back cutting was done in the middle of terminal shoots). The occurrence of the breaking of internal dormancy was decided if the breaking of the terminal bud of bourse shoot occurred within 15 days or not in growth chamber. About 100 bourse shoots were collected by cultivar classification in early December every year and were stored at $5.0^{\circ}C$, and they were placed in growth chamber at one week interval. The chilling requirement of cultivars was expressed in accumulated hours in the field and in the growth chamber under $7.2^{\circ}C$ and $0.0-7.2^{\circ}C$ from the initial point of dormancy to the breaking time of internal dormancy. The results showed that the initial point of dormancy in selected cultivars could occur at the end of September. The breaking time of internal dormancy could occur from the end of January to the early of February. The accumulated hours under $7.2^{\circ}C$ for breaking of internal dormancy were 1,600-2,000 hours, while those of $0.0-7.2^{\circ}C$ were 1,300-1,800 hours. In comparing the different apple cultivars, the chilling requirement of the early flowering cultivars seemed lower than that of the late-flowering cultivars. Based on these results, if the air temperature of Gunwi region rises about $4.0^{\circ}C$ higher than the current one, the breaking time of internal dormancy will be delayed by 2-4 weeks.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.7 no.2
• /
• pp.135-140
• /
• 1995

The procedure of wave energy dissipation due to breaking has been investigated with trains of the regular wave. To obtain the data for wave breaking and its deformation, experiments have been conducted by utilizing a horizontal step adjoining to a combined slope of 1/20 and 1/10. After breaking the wave height decreases by dissipation but attains a stable value at some distance from the breaking point Experimental results show that the stable wave is considerably affected by the wave period. The study gives the general form of stable wave height A new one-dimensional wave deformation model is proposed. being coupled with an approximated shoaling coefficient before wave breaking and the new energy dissipation term after breaking. It was compared with the experimental data. It predicts well the wave height deformation before and after wave breaking even on the abrupt change of the depth.

• Journal of the Korean Society of Industry Convergence
• /
• v.2 no.2
• /
• pp.181-186
• /
• 1999

For an unmanned machining system, the control and disposal of chips is one of the most serious problems at present. In order to perform chip control, feed/land length($F_L$) was introduced, and using this parameter, the cutting performance and chip breaking characteristics of groove-type and the land -angle-type chip formers were assessed. The specific cutting energy consumed and the shape of broken chips with its breaking cycle time were evaluated to find out the ranges of $F_L$ value where efficient cutting and effective chip breaking could be achieved. The C type chip was found to be the most preferable from the view point of cutting efficiency.