• Journal of Navigation and Port Research
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• v.28 no.10 s.96
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• pp.947-953
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• 2004

As a large scale port development in coastal waters proceeds step by step and populations in the vicinity of port are getting increased, the issue on 'how to dispose the treated municipal water and wastewater in harbor' brings peoples' concern. The submarine outfall system discharges the primary or secondary treated effluent at the coastline or in deep water, or between these two. The effluent, which has a density similar to that of fresh water, rises to the sea surface forming plume or jet, together with entraining the surrounding sea water and becomes very dilute. We intended in this paper to investigate the impact on dilution of effluent and the behavior of flume under the conditions of the seasonal and spatial temperature variations, which have not been noticeable in designing effective marine outfall system. To predict and analyze the behaviour and dilution characteristics of plume not just with the effluent temperature, but also with the seasonal variation of temperature of surround water, CORMIX( Cornell Mixing Zone Expert System)-GI have been applied. The results should be used with caution in evaluation the mixing zone characteristics of discharged water. We hope to help for the effective operation of outfall system, probable outfall design, protection of water quality, and warm water discharges from a power plant, etc.

• Journal of Navigation and Port Research
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• v.29 no.6 s.102
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• pp.537-545
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• 2005

Traditionally Jeju island has a mild oceanic climate throughout the year and famous as worldwide resort area bemuse of its pure natural environment and dramatic coastal scenery. But unpredicted coastal erosion problem, mused by variation of environmental conditions from construction of coastal structure and renovation of the existing ports, has raised its head above the water, and is becoming serious these days just like other coastal area in Korea. The phenomena happen here along the seaside of southern part of the island show that severe changes in coastal line from erosion and even witnessed the coastal cliff failure. In advanced countries, coastal engineers and researchers have studied deeply about this kind of problem for a long time. However, as it is not sot active in Korea and lack of research data, there exists difficulties on building protection methods and thoughtless constructions might make it more complicated and fatal to the coastal environment. In this study, we investigated some case studies of other countries and intended to induce and propose some integral protection methods for coastline erosion, considering environmentally sound and water friendly way of development such as artificial reef, floating breakwater, and double cellblock breakwater. Finally, we made analysis on the proposed methods with numerical model test and evaluation on the feasibility of each method.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.3
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• pp.177-185
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• 2012

Wave field measurements were made over a period of 18 days to study the spatial distribution of incident wave on seaweed tarm field around Gumil-up Sea, Wando, Korea. These measured data were compared with data from the Geomun-do ocean weather/wave observation buoy. A numerical simulation model that combined the offshore design wave with the seasonal normal incoming wave was used to study the incident wave distribution surrounding a seaweed farm. The results are summarized as follows. (1) On-site wave measurements showed that the major relationship between maximum and significant wave height was $H_{max}=1.6H_{1/3}$. (2) Offshore incident wave energy reaching the coast was greatly influenced by the wind direction. A north wind reduced the incident wave energy and a south wind increased it. (3) The calculated maximum wave height under the design wave boundany conditions was in the range of 4~5 m and the reduction in the incident wave height ratio ranged from approximately 38.1% to 47.6% at Gumil-up Sea. Under normal wave conditions, the maximum wave heights were 3.6~4.0 m in summer and 2.3~2.7 m in winter while the reduction in the incident wave height ratio was about 41.8% to 49.1%. (4) The sea state in the southern area of Gumil-up was the most affected by ocean waves, whereas the sea state in the northern area was very stable. The significant wave ratio in the south was about six times that in the north.

• Journal of the Korean Society for Marine Environment & Energy
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• v.15 no.3
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• pp.170-176
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• 2012

This paper analyzes the sea state and characteristics during the August 2011 passage of Typhoon Muifa based on data measured at four ocean weather/wave observation stations (buoys) located on the southwestern coast of Korea. When the typhoon arrived in the area approximately 230 km west of Mokpo at 9 PM on August 7, the decrease in air pressure led to increases in sea level of 25.64 cm at the Chilbal-do buoy, 16.43 cm at the Geomun-do buoy, and 9.60 cm at the Geoje-do buoy. The maximum wave height increased at the Geomun-do buoy about seven times faster than at the Chilbal-do buoy. The low water temperature at Chilbaldo during the typhoon passage probably reduced the wave energy. In the face of the oncoming typhoon, the southwest direction of the wind and waves may have been the result of external forces transporting seawater (energy) from the open sea toward the coast. The weather and ocean data from the Mara-do buoy were negatively correlated with those of Chilbal-do, whereas the data from Geomun-do had a positive correlation with those of Geoje-do.

• Journal of Navigation and Port Research
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• v.31 no.6
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• pp.447-454
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• 2007

To assess the port development and maritime traffic environment, the future traffic volume has been estimated using the number of inbound and outbound vessel for a specific port. The estimation of future traffic volume should be considered as an important factor to establish the degree of fairway congestion, the determination of fairway width and the operational role. Until now, the number of in and out vessel for the port has been only estimated mainly, but the type and size of inbound and outbound ships are different depending on the port's characteristics. So, it is difficult to estimate the future traffic volume using the change of only one item. This paper calculates the future traffic volume using the marine traffic characteristic factors as the number of coastal ship and ocean-going ship, the size of ship and the change of cargo volume per a ship etc. And it compared with the results of Artificial Neural Network(ANN) for accurate identification of nonlinear system.

• Journal of Navigation and Port Research
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• v.31 no.6
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• pp.479-484
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• 2007

For calculation of wave field for design of coastal and port structures, generally the wind fields from inland observation record or the predicted waves from deep water wave transformation model are being used. However, for the first case, as we should revise the wave data adopting correcting parameters depending on the distance from the coast and location, it is difficult to extract water waves from wind field. Furthermore, for the second case, because of the calculation which executed under very large grid sizes in the wide domain, the simulation(wave transformation) implied uncertainty in the near shore area and shallow region. So it's difficult to obtain exact data from the simulation. Thus, in this study the calculation of wave field on shallow water is accomplished using the observed data of typhoon 'Maemi' in the Korea Eastern South sea. Moreover, for the accuracy of the calculated wave field, we compared and studied the observed data of wave height and direction on the vicinity of the Ulsan waters. It is proved that the results of this study is more accurate than the existing method with showing ${\pm}1.3%$ difference between observed and calculated wave height distribution in Ulsan waters

• Journal of Navigation and Port Research
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• v.43 no.6
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• pp.475-482
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• 2019

The increase in human use and activity in the oceans is leading to marine pollution and habitat destruction. As a result, in particular, marine animals with a long life cycle and small population are threatened with extinction. Thus, the Korean government designated 11 artificial habitats, such as aquariums and marine museums, as Ex-situ conservation institutions to preserve endangered marine life in 2010. However, studies on the significance and economic value of Ex-situ conservation institutions providing marine life conservation services have not been conducted. Thus, the purpose of this study was to estimate the public's quantitative support for the operation policy of Ex-situ conservation institutions, which is a management method for the protection and propagation of marine animals in Korea. To achieve this, the economic value of the marine animal conservation role of the National Maritime Museum was estimated, operated as an Ex-situ conservation institution for the preservation of green turtles in Korea. By using the representative non-market valuation method for public goods known as the contingent valuation method (CVM), the economic value of the Ex-situ conservation institution (National Maritime Museum) was estimated at approximately 41.8 billion won to a maximum of 78.1 billion won. The results of this study can be applied as basic data for marine animal management policymakers in establishing efficient management plans for endangered marine animals in Korea's coastal waters.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.21 no.12
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• pp.2394-2402
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• 2017

The frequency selective fading by multipaths determines a performance of underwater acoustic communication system in shallow littoral ocean. In this study, a characteristics of underwater acoustic channel and performance of multi-carrier system is evaluated in littoral ocean with a 50m deep water, an effective wave height of 0.5m and sandy mud bottom near Busan city. A multipath delay spread and time and frequency domain are presented as a function of a transmitter-to-receiver range. A bit-error-rate of a 5 channel 4FSK(Frequency Shift Keying) with a transmission rate of 1kbps, is examined and RS(Reed-Solomon) code is also adopted to remove a burst error due to time domain fading. A number of multipath are less than four and a bit-error-rate is decreased as an increase of a transmitter-to-receiver range which gives a congestion of multi-paths resulting in a decrease of time and frequency domain fading. The measured bit-error-rate is about 10-4 at greater than 600m of transmitter-to-receiver range.

• Geophysics and Geophysical Exploration
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• v.20 no.1
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• pp.12-17
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• 2017

We construct 3D SV-wave velocity structure of the crust and the upper mantle beneath East Asia from Rayleighwave group-velocity measurements. For the construction of the SV-wave velocity model at 10 ~ 100 km depth, we used seismic data recorded at 321 broadband stations in Korea, Japan, and China. Rayleigh-wave group-velocity dispersion curves were obtained by using the multiple filtering technique in the period range from 3 to 150 s. High SV-velocity anomalies are imaged beneath the East Sea from 10 km depth to deeper depth, implying that the Moho beneath the East Sea is between at 10 ~ 20 km depth. We estimated the Moho beneath the Korean peninsula to be around 35 km based on the depth where a high-velocity anomaly is observed. The SV-wave velocity model shows prominent fast S-velocity anomalies near northeastern Japan, associated with the subducting Pacific plate. Low-velocity anomalies are found beneath the east coast of the Korean peninsula at 100 km depth, which may play a role in the formation of the Ulleungdo and the Ulleung basin. We observed low-velocity anomalies beneath the Yamato basin at 100 km depth as well, which may indicate the upwelling of fluid from the Pacific plate via dehydration at deeper depth.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.34 no.4
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• pp.384-388
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• 2001

In order to investigate regional variation of food component in the top shells, Omphalius pfeifferi capenteri, caught from Jeju, Sogwipo, Hallim and Songsan, Jeju island, Republic of Korea, food sanitary (heavy metal and volatile basic nitrogen), nutritional (mineral, total amino acid contents, fatty acid composition), taste (extractive nitrogen) components and sensory evaluation (color, texture and taste) were measured. From the result of the contents of heavy metal and volatile basic nitrogen, the top shell might not invoke health risk in using food source, The extractive nitrogen contents of top shell were $343.0\~385.4\;mg/100\;g$. The amounts of total amino acids were $12.5\~13.2\;g/100\;g$, and the major compound among them were glutamic acid, proline and aspartic acid. The major compound among mineral were sodium, calcium, potassium and magnesium. In fatty acid composition, polyenes with essential component or healthy functionality such as 20:4n-6, 20: 5n-3 and 22: 5n-3 were the major components. But, lipid content was extremely small. Judging from the results of chemical and sensory evaluation described a above, food components were not different among top shells caught from various area.