• Journal of Korean Society of Coastal and Ocean Engineers
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• v.14 no.1
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• pp.34-40
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• 2002

In order to estimate the height of long period wave from character of deep water wave, field observation is carried out three wave gauge are arranged by a straight line from the seashore to offshore direction and the result is analyzed. In addition, the existing theory of the mechanism for long period wave producer is verified by field observation, and the relation between deep water wave and long period wave of shallow area is examined. Observed long period wave is coincided with the existing theory for the most part. In order to add the change of time and space of long period wave, the height of long period wave is calculated by the composition of long period wave in each position. As a result, the relation of long period wave and deep water wave is presented more clear. Estimate formula is drew through them.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.5
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• pp.682-689
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• 2011

Recently, there are frequent disasters by Swell-like Wave in the coastal area, Korea peninsula. This phenomenon (Swell-like Wave) has long period above 10 seconds compared with wind wave. To prevent these disasters by the long-period wave in advance, it's necessary to observe it in real time. But existing instruments for wave observation can not observe long-period wave because they mainly are aimed to measure the short-period wind wave. Therefore, in this research it is tried to develop the GPS based Long Period Wave Observation System which real time operation can be realzied in the sea.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2003.08a
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• pp.216-221
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• 2003

황천 시에 쇄파대 내에서 발달한 장주기파는 전빈의 침식에 직집적인 원인이 되는(가여 1992) 등, 쇄파대 내의 표사현상에 큰 영향을 미친다. 쇄파대 내의 부유사 농도가 장주기 변동을 하는 것은 가여ㆍ전중(1983), 시소 등(1985) 등에 의해 현지에서 관측되어 있다 또한 Beach and Sternberg(1988, 1991)는 장주기파가 발달한 때의 쇄파대 내 부유사 농도가 장주기파가 발달하지 않은 경우에 비해 3-4배의 값을 나타내는 것을 지적하면서 장주기파에 의한 내외해 방향(cross shore direction) 부유사 flux의 방향이 주파수나 저면으로부터의 높이에 의해 변화함을 제시하였다. (중략)

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.13 no.3
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• pp.209-229
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• 2001

Simultaneous field measurements of short-period and long-period waves were made at five stations inside or outside Okkye Harbor, which is located in the east coast of Korea. Based on the measured data, spacial and temporal variations of the long-period wave energy were examined. Three smoothing methods were examined for the spectral estimates: fixed interval averaging method, incremental interval averaging method, and moving averaging method. It was shown that a proper smoothing method should be chosen depending on the period of first resonant mode and the length of data being used. By comparing the results obtained using the long-term data with those obtained using two-day data, we showed that it is necessary to analyze the data of calm seas and storm seas separately. The Helmholtz resonant period in Okkye Harbor was found to be about 9.6 minutes with its relative amplification ratio of 9 to 10, and local amplifications were apparent at the periods of 1.2 to 1.3 minutes and 0.7 minute. During calm seas, both at the harbor entrance and inside the harbor the energy of the waves of 9 minutes or longer period was larger than the infra-gravity wave energy by more than 100 times. However, during storm seas the energy level was very high all over the period band, and local amplification was larger than that during calm seas by more than 100 times, especially inside the harbor, Finally it was shown that the energies of the Helmholtz resonant mode and the infra-gravity waves of 1 to 2 minutes are proportional to the storm wave height.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.14 no.3
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• pp.607-618
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• 1994

Effects of wave grouping on the harbor oscillation are studied in order to clarify the energy source of harbor resonance. The resonant periods of Donghae harbor and Imwon harbor are calculated using the boundary integral equation method. Also, the periods of the group-bounded long waves due to the irregular wave group are calculated using the theory developed in this study. Analyzing from the view point of period, it is concluded that the group-bounded long waves due to the irregular wave group can cause resonance in small harbors such as fishery harbors, and heavy ship motion in large harbors such as industrial ones.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2018.11a
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• pp.353-354
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• 2018

스웰 등 장주기파랑은 높은 에너지를 갖고 있어서 바람이 없어도 에너지가 사라지지 않고 전파되어 항만에 이르게 되고, 차폐된 항내수역에서 파고가 증폭되어 대형선박의 접이안과 하역작업을 중단시키는 경제적 손실을 야기한다. 본 실험은 대규모 개발에 따른 장주기 파랑에 의한 반응특성과 부진동의 영향을 검토하였다. 특히, 항만확장외에 외역에 추가적 개발을 위한 매립을 고려하여 항만정온도와 장주기 반응 특성을 파악하여 가능한 대책방향을 검토하고자 하였다.

• Journal of Navigation and Port Research
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• v.27 no.1
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• pp.55-61
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• 2003

The maneuvering equations of motion are derived to express the motion of a ship. The wave forces in the time domain analysis are generated from the frequency transfer function calculated by 3-D source distribution method. The linear wave forces whose periods are equal to those of incident waves and the nonlinear wave forces that make long period drift forces are computed for the simulation. The consideration of irregular waves and nonlinear wave force effects on the slew motion are carried on the analyzing the motion of ship in the regular and irregular waves.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.8 no.2
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• pp.193-203
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• 1996

Long period waves were measured at two stations outside and inside Chukpyon Harbor using two pressure-type wave gauges for one week that covers storm sea period. Based on the collected data the characteristics of long-period resonant oscillations were analysed: the resonant period corresponding to the peak spectral density are slightly different from one to the component wave period with the largest amplification ratio, and the latter period is suggested as that of the first resonant mode. From the analysed field data and numerical modeling, the first resonant mode of Chukpyon Harbor region appeared to be around 12 minutes with amplification ratio of 7, whose amplitude varies 10-20 cm inside of the harbour, and also the second mode appeared to be around 6 minutes. The waves of 2-3 minute periods were resonated apparently in the harbour, which is considered to be generated from group-bounded irregular waves and non-linear wave-wave interaction etc. The linearly decreasing reflection coefficients used in the numerical modeling appeared to be an alternative in calculating reflected waves in harbor.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2016.05a
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• pp.124-126
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• 2016

해안역에서의 대규모 개발은 파랑에너지의 전파에 상당한 변화를 초래한다. 특히, 항만내로 전파되는 파랑장을 변화시켜 기존의 에너지 전달체계에 큰 영향을 야기한다. 따라서, 이러한 파랑에너지의 변화를 사전에 예측하여 항만내의 선박이나 항만구조물의 피해를 막을 수 있다. 그러나 일반적으로 수행되는 항만내의 파랑장 검토 즉, 정온도 검토는 주로 공학적으로 문제가 되는 주기 10~20sec의 풍파와 너울성 파랑에 대하여 수행되고 있다. 그러나 실제 현장에서는 20sec 이상의 장주기 파랑에 의한 선박이나 항만구조물에 상당한 피해를 가져오기도 하지만 이로 인해 연간 부두 접안율이 낮아 항만운영에 어려움을 겪고 있다. 본 실험은 대규모 개발에 따른 장주기 파랑에 의한 반응특성과 부진동의 영향을 검토하였다. 특히, 항내 수제선에 개발이 집중적으로 이루어져 내륙측으로 항만수역을 보완하거나 변경이 어려운 경우 장주기파로 인한 부진동의 영향을 저감하기 위한 시도로 공진수역을 도입하였으며, 이에 대한 반응 특성을 분석하여 장래 항만 재배치 계획에 반영할 수 있는 근거가 될 수 있을 것으로 본다.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 1993.07a
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• pp.130-136
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• 1993

단주기파군에 의하여 발생되는 장주기파를 나타내는 용어로 surf-beats, edge파 그리고 평균수위강하(set-down 또는 group bounded long wave)등이 사용되어지고 있다. 이들의 발생성격에 대한 물리적 특성으로, surf-beats와 edge파는 일반적으로 천해역에서 발생하는 비선형간섭(쇄파특성) 및 해안선의 반사성과 관련있으며 평균수위강하는 단지 단주기파에 의하여 형성된 파군의 특성과 관련을 갖게 된다. (중략)