• Proceedings of the Korean Geotechical Society Conference
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• 2006.03a
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• pp.800-807
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• 2006

Sea dyke construction is simply defined that the cutting procedure of sea water flow. Sea dyke construction is more difficult than in-land construction because it’s placed on deep seabed and exposed sea wave attack. Especially, the final closure of sea dyke is most dangerous due to the fast velocity of tidal flow. The final closure section is consisted with vast rubble and heavy stone gabion, therefore the discharge velocity at land side of final close section is irregularly and sometime occur the fast discharge velocity. In this study, the seepage model test performed to evaluate seepage behavior with tidal variation of final closure and continuous sea dyke section such as discharge velocity, hydraulic gradient, and phreatic line. Based on the seepage model test results, the maximum discharge velocity of final closure section is 1.7m/sec. Also the local discharge velocity increment and vortex is occurred.

• Ocean and Polar Research
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• v.28 no.4
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• pp.475-484
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• 2006

In order to reveal the vertical variation of physical properties in deep-sea sediments, deep-sea sediment cores were collected at 78 stations using a multiple corer in the KR5 area, one of the Korea contract areas for manganese nodule exploration, located in the northeast equatorial Pacific. Based on the color of sediments, sampled sediment cores were characterized into three lithologic units (unit 1,2, and 3). In all sediment cores, three units appear systematically; unit 1 lies at the top of cores and unit 2 and/or unit 3 appear to underlie unit 1 or alternate with unit 3. Unit 1 layer from the top of cores shows dark grayish brown to dark brown with mean thickness of 10.2cm. Unit 2 and 3 layers show very dark brown to black color and yellowish brown to brown color, respectively. According to the physical properties of the deep-sea sediment cores, sediment column can be divided into three sections. Section A $(0{\sim}15cm)$ in subbottom depth consists mostly of unit 1. Mean values of physical properties of section B $(15{\sim}30cm)$ in subbottom depth are similar to those of section C (>30 cm) in subbottom depth. However, the physical properties of section B were more variable than those of section C because of the high activity of bioturbation in section B. These results will provide valuable information for selecting suitable sites for mining manganese nodules in the Korea contract areas.

• Journal of the Korean Geosynthetics Society
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• v.5 no.1
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• pp.25-32
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• 2006

Sea dyke construction is simply defined as a cutting procedure of sea water flow. Sea dyke construction is more difficult than in-land construction because it is placed on deep seabed and exposed sea wave attack. Especially, the final closure of sea dyke is most dangerous due to the fast velocity of tidal flow. The final closure is consisted with vast rubble and heavy stone gabion, therefore the discharge velocity at land side of final close section is irregularly and sometime occur the fast discharge velocity. In this paper, the seepage model test performed to evaluate seepage behavior of final closure and continuous sea dyke section such as discharge velocity, hydraulic gradient, and phreatic line with installation of bottom protection filter mat. Based on the seepage model test results, the maximum discharge velocity of final closure section is 1.7m/sec and the discharge velocity is decreased maximum 23.7% with installation of bottom protection filter mat.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.03a
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• pp.153-158
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• 2008

In this study, piping and slope stabilities of sea dike were analyzed through pore pressure-mechanic coupled analysis. Through decrement of sea dike inclination, to confirmed cross-section reduction possibility of multi-function sea dike.

• Journal of Ocean Engineering and Technology
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• v.24 no.1
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• pp.47-52
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• 2010

This study presents a modified scheme for the radar image simulation of sea waves. A simulated radar image was obtained by taking into account the dot product of the directed vector from the radar and the normal vector of the sea surface. Moreover, to calculate the radar image, we used the radar received power and radar cross section. To demonstrate the effectiveness of the proposed scheme, the wave spectrum from field data was utilized to obtain the simulated sea waves. The radar image was simulated using numerically generated sea waves. The wave statistics from the simulation agrees comparatively with those of the original field data acquired by real radar measurements.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1727-1734
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• 2008

After the final closure of sea dyke, seepage behaviour of embankment is highly changed by variation of water head different between tide wave and controlled water level at fresh lake. Especially, the seepage behaviour of bottom protection layer of final closure section is more important factor for structural and functional stability of sea dyke, because of the bottom protection layer of final closure section is penetrated sea side to fresh lake. Even though bottom protection layer was filled with dredged fine sand, it has a high permeability. In this paper, mainly described about the seepage velocity and borehole image of bottom protection layer filled with dredged sand after final closure. Various in-situ tests such as BIPS (Borehole Image Processing System) and ABI (Acoustic Borehole Imager) survey, wave velocity measuring, and color tracer survey were conducted to evaluate the seepage behavior of bottom protection layer. Based on the in-situ tests, the bottom protection layer of final closure section was almost filled with dredged sand which is slightly coarse grain sand and there have sea water flow by water head different between tide wave and controlled water level at fresh lake. Also, comply with tracer survey results, the sea water flow path was not exist or generated in the bottom protection layer. However, because of this result not only short term survey but also just one test borehole survey results, additional long term and other borehole tests are needed.

• Journal of The Korean Society of Agricultural Engineers
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• v.56 no.6
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• pp.159-167
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• 2014

In this study the process of normalizing hydraulic head loss rate was developed for the purpose of estimation of seepage blocking state at each seepage segment in sea dike embankment. Pore water pressure sensors were installed with some interval along seepage path, then the hydraulic head loss rate at each segment between pore water pressure sensors was calculated, and then the calculated hydraulic head loss rate was normalized based on seepage path length. The comparison of normalized hydraulic head loss rates showed that the cross section of sea dike embankment was homogeneous approximately and the width of cross section was long enough to blocking tide water.

• Korean Journal of Ichthyology
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• v.27 no.1
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• pp.21-25
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• 2015

We studied the effects of temperature and salinity on the egg development and larvae of sevenband grouper Epinephelus septemfasciatus under sea cage culturing condition. In regard to rearing environment, the water temperature is $21.5{\sim}23.5^{\circ}C$ (mean $22.0{\pm}0.05^{\circ}C$) and the salinity is 32.0~33.0 psu (mean $32.5{\pm}0.05psu$). The time of egg development was positively proportional to water temperature with 29 hrs, 27 hrs, 24 hrs, 17 hrs, 15 hrs after fertilization in $15^{\circ}C$, $20^{\circ}C$, $25^{\circ}C$, $30^{\circ}C$, $35^{\circ}C$ respectively. Each of the salinity hatching rate was 80% in the section of 15 psu, 81.8% in the section of 25 psu, 89.1% in the section of 30 psu, and 79.1% in the section of 35 psu. All things considered, the highest hatching rate appeared in the range of the section of 25~30 psu. Abnormalities of low salinity section, such as 15 psu (20.0%) and 20 psu (18.2%), was lower than the abnormalities of 35 psu that belongs to high salt section. The relation between the time of egg development (t:hour) and water temperature ($T:^{\circ}C$) was represented by the mathematical formulae. The mean biological minimum temperature was $5.4^{\circ}C$.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.970-978
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• 2010

In this study, interior noise of the high speed EMU was estimated by statistical energy analysis (SEA) method. Based on the data measured at a distance of 25m from a running train, exterior noise of the running train was calculated. And then it was designed as noise sources in VA ONE, a commercial software of SEA. coupling and damping loss factor of high speed EMU studied in previous studies is used. The interior noise of the train was estimated for a open-land section. The analysis of interior noise of HST in the tunnel section will be estimated through same method.

• Journal of Construction Engineering and Project Management
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• v.3 no.2
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• pp.49-57
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• 2013

A sea dike construction has been increased in Korea because of the actively deployed reclamation project in basis of efficient application in land. The degree of completion in sea dike construction is affected by final closing construction, which has a lot of uncertainty that often results in higher accidents rate. Therefore, this research identified risk factors of final closing construction and classified them. This research examines the likelihood and its impact for each risk factor and calculates the risk degree as to the risk matrix. Based on this, the impact and the environmental conditions that affect to risk factors are investigated and further responsive methods are established for each risk factor. Ultimately, this research attempts to provide the risk retrenchment method for inspectors by proposing risk estimation model, responsive action list, and risk management process.