• Journal of the Korean Society for Marine Environment & Energy
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• v.9 no.3
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• pp.141-147
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• 2006

A newly designed floating breakwater made of Polyethylene with considering the introduction of new material for being harmony with environment and stability of the floater is developed for a marine ranching. In this study, the new concept in which incident wave dissipates its energy due to the vortex shedding by passing through the pipes and sheets is selected for wave breaking mechanism. Model experiment in order to te st its capability is performed for the regular and irregular waves in ocean engineering basin. Good capability to break the incident wave within the 6 seconds of period and 1 m of height is shown. Breaking efficiency for long period wave is not so good in regular and irregular wave. The results of this study will contribute to the design and construction of the floating breakwater.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1427-1439
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• 2008

The quality of track-bed fills of railways has been controlled by field measurements of density (${\gamma}_d$) and the results of plate-load tests. The control measures are compatible with the design procedures whose design parameter is $k_{30}$ for both ordinary-speed railways and high-speed railways. However, one of fatal flaws of the design procedures is that there are no simple laboratory measurement procedures for the design parameters ($k_{30}$ or, $E_{v2}$ and $E_{v2}/E_{v1}$) in design stage. A new quality control procedure, in parallel with the advent of the new design procedure, is being proposed. This procedure is based upon P-wave velocity involving consistently the evaluation of design parameters in design stage and the field measurements during construction. The key concept of the procedure is that the target value for field compaction control is the P-wave velocity determined at OMC using modified compaction test, and direct-arrival method is used for the field measurements during construction. The procedure was verified at a test site and the p-wave velocity turned out to be an excellent control measure. The specifications for the control also include field compaction water content of $OMC{\pm}2%$ as well as the p-wave velocity.

• Journal of The Korean Astronomical Society
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• v.29 no.spc1
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• pp.281-282
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• 1996

• Journal of the Korean Society of Visualization
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• v.3 no.1
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• pp.43-46
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• 2005

• Journal of Contemporary Eastern Asia
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• v.1 no.1
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• pp.4-5
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• 2002

• 한국전산유체공학회:학술대회논문집
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• 2004.10a
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• pp.1-1
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• 2004

• 한국신재생에너지학회:학술대회논문집
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• 2011.05a
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• pp.167.1-167.1
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• 2011

Sustainable energy generation is becoming extremely imperative due to the expected limitations in current energy resources and to reduce pollution. Especially, because of its considerable energy potential, ocean wave energy has been investigated with regard to power generation. To develop large high power wave generator system, it is important to make a small scale proto type and to test that. Thus the objective of this research is to examine the characteristics of a mechanically excited generator system having small power capacity experimentally. The water reservoir (4 m length, 1.5 m width and 1.8 m depth) having a wave maker to make arbitrary height and period of the water wave was made. The proto type consists of three main parts; a buoy, rack-pinion base one-way mechanism, and a wave generator(Fig.1). The water wave is going up and down and the hexahedron buoy is following the wave. The rack gear attached to the buoy is also going up and down to roll the pinion connected to an electric generator then it produces electricity. The experiments were performed with several conditions of water waves, and the power outputs over 30 W could be measured for some conditions. In future works, to achieve higher performance for the proto type, the effects of primary parameters (buoy shape and mass, etc.) on the system efficiency will be identified.

• Journal of the Korean Geotechnical Society
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• v.19 no.4
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• pp.299-310
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• 2003

In the evaluation of the subgrade stiffness structure by the SASW method, the calculation of the phase velocities is the important task controlling the reliability of the result. The interpretation of the phase spectrum should precede the phase-velocity calculation in the current practice of the SASW method. The difficulty involved in the interpretation prohibited the SASW method from being spread over to the industry. This study proposed a new method called the frequency-wave number technique, which is based on the frequency-wave number relationship of the surface wave in the multi-layered system. The frequency-wave number technique eliminates the expertise in the interpretation of the phase spectrum, automates the phase-velocity calculation and expedites the determination of the phase-velocity dispersion curve. To verify the validity of the proposed frequency-wave number method, the transfer function determined from the numerical simulation of the SASW measurements was used fir the calculation of the automatic calculation of the phase velocities and compared with the phase velocities by WinSASW employing the phase-unwrapping method. Also, the proposed method was applied to the real SASW measurements performed at$\bigcirc$$\bigcirc$area in GyeongGi-Do to see how the proposed method works with the real measurements.

• Proceedings of the KOSOMBE Conference
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• v.1998 no.11
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• pp.181-182
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• 1998

In previous study for correlation between P-wave Signal Averaged Electrocardiography (SAECG) and Paroxysmal Atrial Fibrillation (PAF) subjects, we showed that the duration of P-wave in subjects is longer than in controls. In this respect, the P-wave SAECG is a new method proving to be an accurate and independent noninvasive marker for the risk of PAF. To prove this suggestion, accurate detection and alignment of P-wave are indispensible. In previous study, we measured P-wave duration by manual. So it was not accurate and consistent. To measure the P-wave duration accurately and automatically, we have developed an automatic algorithm for P-wave duration measurement. We showed that the duration of P- wave in the subjects is longer than in controls with this algorithm.

• Atmosphere
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• v.27 no.2
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• pp.199-211
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• 2017

The cold surges over East Asia can be grouped to two types of the wave-train and the blocking. Recently, the observational study proposed new dynamical index to objectively identify cold surge types. In this study, the dynamical index is applied to the simulations of 10 climate models, which participate in the Coupled Model Intercomparison Project Phase 5 (CMIP5). Focusing on assessment of cold surge simulation, we discuss characteristic of the wave-train and blocking cold surges in the climate models. The wave-train index (WI) and the blocking index (BI) based on potential temperature anomalies at dynamical tropopause over the subarctic region, the northeast China, and the western North Pacific enable us to classify cold surges in the climate models into two types. The climate models well simulate the occurrence mechanism of the wave-train cold surges with vertical structure related to growing baroclinic wave. However, while the wave-train in the observation propagates in west-east direction across the Eurasia Continent, most of the models simulate the southeastward propagation of the wave-train originated from the Kara Sea. For the blocking cold surges, the general features in the climate models well follow those in the observation to show the dipole pattern of a barotropic high-latitude blocking and a baroclinic coastal trough, leading to the Arctic cold surges with the strong northerly wind originated from the Arctic Sea. In both of the observation and climate models, the blocking cold surges tend to be more intense and last longer compared to the wave-train type.