• Journal of the Korean Society of Marine Environment & Safety
• /
• v.28 no.6
• /
• pp.890-898
• /
• 2022

Dispersion of suspended sediment, caused by coastal and marine development, is a key item in assessing marine environmental impact as it adversely affects marine life by increasing the level of turbidity and decreasing the amount of sunlight in seawater. However, its estimation has not been reliable because of the absence of a standard for the data measurement and divergent approaches to the impact assessment. In this study, we examined the estimation models from 58 Marine Environmental Impact Statements (MEISs, 2012-2014) to identify the gaps in the assessment and devise ways of improving the estimation. We developed four index items-grid system; unit load, particle size, and settling velocit-to evaluate their reliability in the estimation. The mean reliability score of each index was overall low-25 for grid system, 60 for unit load, 34 for particle size, and 17 for settling velocity. To ensure high reliability, it is important to develop a standard guideline that defines precise measurement of suspended sediment for unit load and settling velocity by particle size, followed by a grid system with compatible size for modelling. This can improve the estimation and thus underlie coherent impact assessment of suspended sediment dispersion on marine environment.

• Journal of Advanced Marine Engineering and Technology
• /
• v.34 no.1
• /
• pp.183-194
• /
• 2010

A suitability analysis for marine afforestation was carried out on physical items based on slop rate, bottom sediment, light intensity, velocity, and wave at north Geomoon waters in Korea. The data from each physical item were changed to a GSDM (Gridded Spatial Distribution Map) using Kriging interpolation. A GSDM grid includes information, and each grid was given a SI (suitability index) of 3 grades(SI of first suitability was 100, SI of second suitability was 50, and non-suitability had no SI). According to the analysis results of all overlaid GSDM, first suitability had 500 SI, and suitability area was 0.25ha. Second and third suitability had 400~450 SI, and suitability area was 2.36ha, 1.80ha, respectively. Therefore, the results suggest that reefs installed for marine afforestation should be anti-slip types against steep slope, and the target species need to include algae with low compensation light intensity in second and third suitability.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.25 no.1
• /
• pp.1-10
• /
• 2013

In this study, impact vibration tests are applied to analyze the vibration characteristics of caisson-type breakwater, and the results obtained from vibration tests are compared with numerical simulation results considering fluid-soil-structure interaction effects to verify the feasibility of a numerical analysis model. It is found that natural frequencies are reduced as amount of 1.7-4.3% after additional parapet structure is added to increase the height of breakwater, and the same results was observed from the numerical simulation study. Through the comparison, it was verified that the vibration tests and numerical simulation study can be applied to evaluate the vibration characteristics of caisson-type breakwater.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.40 no.4
• /
• pp.360-366
• /
• 2004

This paper presents a method analyzing the motion of cylindrical buoy moored at 2 points and tensions action on each mooring line under the action of periodic waves. It was found that submersible buoy was more effective than floating one in the severe conditions considering its dynamic motions, wave forces, and mooring line tensions. The wave induced its dynamic responses and mooring line tensions peak when the ratio d/${\lambda}$ of the buoy length d to the waves length ${\lambda}$ was 0.66 due to its natural frequency. The results of this study were in agreement with the existing measurement ones, however, further verifications are needed considering resonance of cylindrical buoy and its displacements to wave height by a series of model tests.

• Journal of Korean Society of Coastal and Ocean Engineers
• /
• v.24 no.3
• /
• pp.166-178
• /
• 2012

In order to simulate storm surge for the west coast, complex physics of asymmetrical typhoon wind vortex, tide and wave are simultaneously incorporated on a fine finite element mesh extended to the North Western Pacific sea. Asymmetrical vortex based on maximum wind radii for each quadrant by JTWC's best tracks are input in pADCIRC and wave stress is accounted by dynamic coupling with unSWAN. Computations performed on parallel clusters. In hindcasting simulation of typhoon Kompasu(1007), model results of wave characteristic are very close with the observed data at Ieo island, and sea surface records at major tidal stations are reproduced with satisfaction when typhoon is approaching to the coast. It is obvious that increasing of local storm surges can be found by introducing asymmetrical vortex. Thus this approach can be satisfactorily applied in coastal hazard management against to storm surge inundation on low level area and major harbor facilities.

• Journal of the Korean Society of Fisheries and Ocean Technology
• /
• v.37 no.2
• /
• pp.140-146
• /
• 2001

In order to analyze the photodegradation of plastic materials for floats or frames of fisheries facilities, weathering experiment on 3 kinds of plastic materials like high density PE of Korea(KHDPE) and Norway(NHDPE) and high strength PVC(Hi-PVC) was carried out during 900 hours exposure by using xenon light source of weather-Ometer. The results obtained are as follows; With increasing of ultraviolet radiation(UVR) time, a remarkable losses in the mechanical properties of each specimen were observed except for the remaining strain of HDPE materials. As NHDPE lost almost 15% of its initial tensile stress during a 900 hours exposure followed by KHDPE 12% and Hi-PVC 6%. In addition, the remaining tensile stress RS(kg/$mm^2$) decreases almost linearly with the lapse of exposure time to light Y(Year) and the empirical equations of each specimen computed as follows; KHDPE : RS=2.6769-0.0003Y($r^2$=0.63) Hi-PVC : RS=5.3470-0.0003Y($r^2$=0.91) NHDPE : RS=2.4929-0.0004Y($r^2$=0.97) It was observed by scanning electron microscope that all specimens with UVR time had started to decompose and had bubbled areas and small holes.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.18 no.1
• /
• pp.25-32
• /
• 2012

To arrange effectively artificial reefs for marine afforestation, tidal currents were analyzed by numerical experiments. The numerical experiments were carried out by EFDC(Environmental Fluid Dynamics Code), and water column was vertically divided 5 layers. Tidal current patterns showed to be affected by main current at outside of study area, and circle currents of two were observed from analysis of residual currents. The calculated harmonic constants of tide and tidal current agreed well with those of observations at two stations for tide and two stations for tidal current. The model successfully reproduced the tidal current around the Geomoondo marine afforestation. It suggest that artificial reefs for marine afforestation should be installed belt zone at study area.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.31 no.3D
• /
• pp.441-450
• /
• 2011

Recent construction projects consist of large and complex facilities, which project management information system (PMIS) is used for managing construction cost and schedule. The ministry of land, transport and maritime affairs (MLTM) is using a continuous acquisition and life-cycle support (CALS) system for managing the public construction projects. This study attempts to survey some problems of the CALS system in practical application, and then suggests the new functions to improve practical application of the CALS system. All functions in each menu were analyzed in the practical application aspect. All projects ordered from MLTM should use the CALS system as a PMIS, but the practical application is limited in partial functions and special working group. And the utilization of system is focused on simple tasks and report process. One of main reason is that the system is using numerical data rather than graphical data. This study suggests new functions and a visualized management method that can improve the practical applicability using a 4D object in each current functions.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.36 no.6B
• /
• pp.683-688
• /
• 2011

Current is change to concept that management traffic of ship os magnified gradually to near shore waters from harbor. Therefore, introducing the technology of AIS in the ground station, lighthouse, bouy, sea facilities etc.. that is support equipment for safety sailing of ship and safety security of harbor and ship administration. The operation and maintenance of AIS for aids to navigation are required to efficient method. With this actuality, sea advanced nation of EU, USA, Japan that has been apply for developing AtoN AIS equipment that is connected equipment of technology standard in IALA. Because of it is expected to depend equipment in income, that is required to domestic technology of the AtoN AIS. This paper is targeted to development that is suitable automation AtoN AIS equipment in environmental peculiarity for constructor AtoN operating administration center. It has been realization send protocol for information interchange.

• 한국해양학회지
• /
• v.1
• /
• pp.49-55
• /
• 1971

After the heavy precipitation from April 1969 to September 1970, more than 1.359 10$\^$6/㎥ of fresh water was discharged through diversion channel of the Namgang Dam. The sands and muds in the northern Sachon Bay were moved and swept away by the strong southsard flow which was observed to be speedier than five knots. The shellfish culture facility as well as the oysters and bivalves were buried. In Sachon Bay, a southward surface ebb current of approximately one knot stratifies above the northward flow of approximately 0.5 knot, which seems to be similar to the salt wedge estuary. The stratified current is responsible for the breaking of the gill nets and other fishing gears. The salinity of sea water in Chinju Bay decreased remarkably and the abnormal low salinity water lower than 5 was distributed in Sachon Bay. The low salinity water front was observed in eastern Chinju Bay and the Samchonpo Channel, where the salinity was increased from 4.6 to approximately 30 within half a tidal cycle. These caused the oysters and bivalves die, and drove anchovies and octopus out to the sea and prevented them from approaching the bay. The decrease of salinity causes the decrease of density and osmotic pressure of sea water. Turbid water would prevent the sunlight from penetrate into deep layer.