• 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.

• Journal of Navigation and Port Research
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• v.27 no.6
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• pp.677-682
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• 2003

The long-period gravity wave, the wave period from some ten seconds to some minutes, induces not only the big sway of a ship moored and berthed in the harbor due to the horizontal long-distance motion of a water but also strong exfoliated flow and vortices near the harbor entrance. They muse serious problems on the safety navigation of vessels entering and leaving the harbor, but this gravity wave has not been searched sufficiently yet. Then it is quite important to reveal the characteristics of this long-period gravity wave ana to solve various problems induced by this wave. The long-period gravity wave measurement system with arrayed buoys installed the kinematic GPS was already proposed, which provides the precise propagating direction of the long-period gravity wave. In this paper, the observation results of the wave measurement system are shown by the MUSIC method And the propagating wave direction was estimated precisely enough in comparison with other results used other method.

• Journal of the Korean Solar Energy Society
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• v.38 no.5
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• pp.1-9
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• 2018

The purpose of this study is to analyze the urban heat island ultimately by analyzing long-wave radiation which is the dominant factor of night minimum temperature formation. We observed during two months with four elements which is long and short wave radiation, temperature, relative humidity. And we analyzed the correlation between the four factors of long-wave radiation, temperature, cloud form, and cloud amount during the summer two months on the night time. Observations were carried out at two sites in Daegu and nearby. The results are as follows. (1) Long-wave radiation change per $1^{\circ}C$ in summer was larger than winter. (2) Long-wave radiation amount is affected by temperature change when the amount of cloud is small. (3) Low cloud was analyzed to have more influence on long-wave radiation than high cloud.

• Journal of the Korean Solar Energy Society
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• v.37 no.6
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• pp.93-102
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• 2017

Interpretation of relevance between long-wave radiation and meteorological elements is recognized as an essential element for understanding the underlying mechanism of urban thermal environment formation. In this study, we analyzed relation between three elements : long-wave radiation, temperature, and lower-middle class cloudiness. The correlation was analyzed through field observations. The results are as follows. (1) Temperatures and long-wave radiation increased from January to March. This phenomenon has been confirmed in urban and suburban areas. (2) Long-wave radiations showed a tendency to increase clearly with increasing cloudiness.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.09a
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• pp.155-162
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• 2001

In this study, it was performed that the seismic response analysis using long period earthquake wave and short period earthquake wave on dynamic behavior of concrete gravity dam. The results showed that if the same magnitude earthquake waves acted on concrete dam, the maximum displacement and stress at dam crest of long period wave(0funato wave) were about 30 % larger than those of short period wave(Hachinohe wave). And the response acceleration of dam crest was amplified about 5 times in long period earthquake wave and about 3 times in short period earthquake wave.

• Journal of Navigation and Port Research
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• v.41 no.5
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• pp.329-336
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• 2017

This study suggests a general process of analyzing the mooring and cargo handling limit waves, which is an incident to the new energy port under long wave agitation. To reduce damages of ships and harbor structures due to strong wave responses, it is necessary to predict the change of wave field in the mooring berth to make the proper decision by dock master. The berthing area at a new LNG port in the east coast of Korea in this study is frequently affected by oscillations from waves of 8.5~13s periods in the wintertime. The long period waves give difficulties on port operation by lowering the annual berthing ratio. It needs to find the event waves from the real time offshore wave records, which cause over the mooring limits. For that purpose, the wave records from field measurement and offshore wave buoy were analyzed. From numerical simulation, the response characteristics of long period waves in the berthing area were deduced with or without breakwater expansion plan, analyzing the offshore field wave data collected for two years. Some event wave cases caused over the cargo handling and mooring limits as per the standard Korean port design guideline, and those were used for the decision of port operation by dock master, comparing with the real time offshore wave observations.

• Journal of Power System Engineering
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• v.13 no.2
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• pp.63-70
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• 2009

This paper discusses the influence on long-tenn predictions of the ship response in ocean by using the Global Wave Statistics data, GWS, and wave information from the remote sensing satellites. GWS's standard scatter diagrams of significant wave height and zero-crossing wave period are suggested to be corrected to a round number of 0.01/1000 fitted with a statistical analytic model of the conditional lognormal distribution for zero-crossing wave period. The GEOSAT satellite data are utilized which presented by I. R. Young and G. J. Holland (1996, named as GEOSAT data). At first, qualities of this data are investigated, and statistical characteristic trends are studied by means of applying known probability distribution functions. The wave height data of GEOSAT are compared to the data observed onboard merchant ships, the data observed by measure instrument installed on the ocean-going container ship and so on. To execute a long-tenn prediction of ship response, joint probability functions between wave height and wave period are introduced, therefore long-term statistical predictions are executed by using the functions.

• Journal of Ocean Engineering and Technology
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• v.16 no.2
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• pp.21-26
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• 2002

In this study, the characteristics of long period waves are analyzed by field observation at Sokcho harbor on the eastern coast of Korea. firstly. the pressure data obtained from field observation are transformed into water surface elevations and the wave by wave analysis is applied to the observed wave data. also, we select long period waves by setting up the range 30-200sec, and suggest the relationship between ordinary waves and long period waves using the concept of the significant wave height. and, we examine the effects oft he long period waves on the rate of the harbor operation. The observation results demonstrate that the long period waves with heights of 1.2-14.6cm and periods of 35.8-162sec exist at Sokcho harbor. also, we found the rates of harbor operation based on long period waves are 61.8%-99.5% lower than the usual rates of 93.8%-100%.

• Journal of Ocean Engineering and Technology
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• v.21 no.5
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• pp.1-8
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• 2007

A long wave induced by a Gaussian-shape submarine landslide is simulated by a 2D fully nonlinear numerical wave tank (NWT). The NWT is based on the boundary element method and the mixed Eulerian/Lagrangian approach. Using the NWT, physical characteristics of land-slide tsunami, including wave generation, propagation, particle kinematics, hydrodynamic pressure, run-up and depression, are simulated for the early stage of long wave generation and propagation. Various sliding mass heights are applied to the developed model for a systematic sensitivity analysis. In particular, the fully nonlinear NWT results are compared with linear results (exact body-boundary conditions with linear free-surface conditions) to identify the nonlinear effects in the respective cases.