• Title/Summary/Keyword: 파랑계측

Search Result 86, Processing Time 0.018 seconds

Development of a Moving Body Type Wave Power Generator using Wave Horizontal Motions and Hydraulic Experiment for Electric Power Production (파의 수평운동을 이용한 가동물체형 파력발전장치의 개발과 전력생산에 관한 수리실험)

  • Hwang, Seong Su;Lee, Dong Soo;Yang, Kyong Uk;Byun, Jung Hwan;Park, Il Heum
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.28 no.2
    • /
    • pp.73-80
    • /
    • 2016
  • To reduce the mechanical energy loss and to get the high energy efficiency, an apparatus of wave power generation inducing a consistent one way rotating motion from the wave reciprocation motions was developed and the hydraulic experiments for the real electric power production were conducted and the results were discussed. In the experiments for the shape of the buoyant tank, the efficiency of the fixed 9 cm diameter type enduring the wave plate weight was 14.6% and this was the best result for all shapes. But although the free sliding type was expected to represent a high efficiency, the experiments did not show a good result as 8.5% efficiency. Therefore, the shape of buoyant tank was decided as the fixed 9 cm diameter type in the next all tests. In the experiments for the various incident waves, when the water depth was 90 cm, the average efficiencies were measured as 3.9% in the 2nd gear, 4.9% in the 3rd gear, 4.9% in the 4th gear, 12.0% in the 5th gear, 10.0% in the 6th gear, 3.1% in the 7th gear, and 3.0% in the 8th gear. Also, when the water depth was 80 cm, the average efficiency was shown as 15.0% with 5th gear condition. Therefore the high average efficiency as 13.5% was given with 80~90 cm water depth and the 5th gear in the model.

Performance of Oscillating Water Column type Wave Energy Converter in Oblique Waves (사파중 진동수주형 파력발전장치의 성능평가)

  • Jin, Jiyuan;Hyun, Beom-Soo;Hong, Keyyong;Liu, Zhen
    • Journal of the Korean Society for Marine Environment & Energy
    • /
    • v.17 no.3
    • /
    • pp.182-188
    • /
    • 2014
  • In an oscillating water column (OWC)-type wave energy conversion system, the performance of the OWC chamber depends on the chamber shape, as well as the incident wave direction and pressure drop produced by the turbine. Although the previous studies on OWC chambers have focused on wave absorbing performance in ideal operating conditions, incident waves do not always arrive normally to the OWC chamber in real sea conditions, especially in fixed devices. The present study deals with experiments and numerical calculations to investigate the effects of wave direction on the performance of the OWC chamber. The experiments were carried out in a three-dimensional wave basin for five different wave directions, including the effect of turbine using the corresponding orifice. The wave elevation inside the chamber was measured at the center point under various incident wave conditions. The numerical study was conducted by using a numerical wave tank-based volume-of-fluid model to compare the results with experimental data and to reveal the detailed flows around the chamber.

Field observation of sediment suspension in the surf zone (쇄파대의 저질부유에 관한 현지관측)

  • Shin, Seung-Ho;Kuriyama, Yoshiaki
    • Journal of Navigation and Port Research
    • /
    • v.27 no.4
    • /
    • pp.455-463
    • /
    • 2003
  • Time series of suspended sediment concentration, surface elevation and velocity were measured and analysed to investigate the role of waves and the predominance of infra-gravity wave component for sediment suspension phenomena in the surf zone. For the investigation in detail, we adopted the cross spectral analysis method between suspended sediment concentration and the characteristic values of wave, and ensemble average analysis method about long-period wave component, which is dominant to sediment suspension in the measurement point. The obtained results are summarized as follows: 1)The relationship between suspended sediment concentration and the characteristic values of wave is stronger for the long-period standing wave components(about 60s and 30s where the nodal point of the first mode and the anti-nodal point of the second mode are located at the measurement point, respectively) than the long wave components(about 100s), which have the most energetic power, 2) and also, it is cleared that suspended sediment concentration is increased in the case of the phase, the velocity components of the first mode long-period standing wave(60sec) were accelerated toward on-shore direction, that is, the water surface in offshore side is higher than on-shore side.

Estimation of the Input Wave Height of the Wave Generator for Regular Waves by Using Artificial Neural Networks and Gaussian Process Regression (인공신경망과 가우시안 과정 회귀에 의한 규칙파의 조파기 입력파고 추정)

  • Jung-Eun, Oh;Sang-Ho, Oh
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.34 no.6
    • /
    • pp.315-324
    • /
    • 2022
  • The experimental data obtained in a wave flume were analyzed using machine learning techniques to establish a model that predicts the input wave height of the wavemaker based on the waves that have experienced wave shoaling and to verify the performance of the established model. For this purpose, artificial neural network (NN), the most representative machine learning technique, and Gaussian process regression (GPR), one of the non-parametric regression analysis methods, were applied respectively. Then, the predictive performance of the two models was compared. The analysis was performed independently for the case of using all the data at once and for the case by classifying the data with a criterion related to the occurrence of wave breaking. When the data were not classified, the error between the input wave height at the wavemaker and the measured value was relatively large for both the NN and GPR models. On the other hand, if the data were divided into non-breaking and breaking conditions, the accuracy of predicting the input wave height was greatly improved. Among the two models, the overall performance of the GPR model was better than that of the NN model.

An Experimental Study on the Estimation Method of Overtopping Discharge at the Rubble Mound Breakwater Using Wave-Overtopping Height (월파고를 이용한 사석경사제의 월파량 산정방법에 관한 실험적 연구)

  • Dong-Hoon Yoo;Young-Chan Lee;Do-Sam Kim;Kwang-Ho Lee
    • Journal of Navigation and Port Research
    • /
    • v.48 no.3
    • /
    • pp.192-199
    • /
    • 2024
  • Wave overtopping is a significant natural hazard that occurs in coastal areas, primarily driven by high waves, particularly those generated during typhoons, which can cause coastal flooding. The development of residential and commercial areas along the coast, driven by increasing social and economic demands, has led to a concentration of people and assets in these vulnerable areas. This, coupled with long-term sea level rise and an increase in typhoon frequency, has heightened the risk of coastal hazards. Traditionally, the evaluation of wave overtopping volumes has relied on directly measuring the collected volume of water that exceeds the crest height of structures through hydraulic model experiments. These experiments are averaged over a specific measurement period. However, in this study, we propose a new method for estimating individual wave overtopping volumes. We utilize the temporal variation of wave overtopping heights to develop an observation system that can quantitatively assess wave overtopping volumes in actual coastal areas. To test our method, we conducted hydraulic model experiments on rubble mound breakwaters, which are commonly installed along the Korean coast. We introduce wave overtopping discharge coefficients, assuming that the inundation velocity from the structure's crest is the long-wave velocity. We then predict overtopping volumes based on wave overtopping heights and compare and review the results with experimental data. The findings of our study confirm the feasibility of estimating wave overtopping volumes by applying the overtopping discharge coefficients derived in this study to wave overtopping heights.

Analysis of Shoreline Changes from Aerial Photographs at Oregon Inlet Terminal Groin (Oregon 하구에 위치한 방사제 주위에서의 항공사진을 이용한 해안선 변화해석)

  • Hwang, Kyu-Nam
    • Journal of Korean Society of Coastal and Ocean Engineers
    • /
    • v.9 no.3
    • /
    • pp.155-164
    • /
    • 1997
  • A comprehensive and systematic field monitoring program was initiated since October 1989, in order to investigate the temporal and spatial variation of shoreline position at northern part of Pea Island, North Carolina. Aerial photographs were taken every two months on the shoreline extending from the US Coast Guard Station at the northern end of Pea Island to a point 6 miles to the south. Aerial photographs taken were digitized initially to obtain the shoreline position data. in which a wet-dry line visible on the beach was used to identify the position of shoreline. Since the wet-dry line does not represent the “true" shoreline .position but includes the errors due to the variations of wave run-up heights and tidal elevations at the time the photos taken, it is required to eliminate the tide and wave runup effects from the initially digitized shoreline .position data. Runup heights on the beach and tidal elevations at the time the aerial photographs taken were estimated using tide data collected at the end of the FRF pier and wave data measured from wave-rider gage installed at 4 km offshore, respectively A runup formula by Hunt (1957) was used to compute the run-up heights on the beach from the given deepwater wave conditions. With shoreline position data corrected for .wave runup and tide, both spatial and temporal variations of the shoreline positions for the monitoring shoreline were analyzed by examining local differences in shoreline movement and their time dependent variability. Six years data of one-mile-average shoreline indicated that there was an apparent seasonal variation of shoreline, that is, progradation of shoreline at summer (August) and recession at winter (February) at Pea Island. which was unclear with the uncorrected shoreline position data. Determination of shoreline position from aerial photograph, without regard to the effects of wave runup and tide, can lead to mis-interpretation for the temporal and spatial variation of shoreline changes.nges.

  • PDF