• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.15 no.2
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• pp.51-61
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• 2010

Surface particulate organic carbon (POC) concentration was measured in the Northeastern Gulf of Mexico on 9 cruises from November 1997 to August 2000 to investigate the seasonal and spatial variability related to synchronous remote sensing data (Sea-viewing Wide Field-of-view Sensor (SeaWiFS), sea surface temperature (SST), sea surface height anomaly (SSHA), and sea surface wind (SSW)) and recorded river discharge data. Surface POC concentrations have higher values (>100 $mg/m^3$) on the inner shelf and near the Mississippi Delta, and decrease across the shelf and slope. The inter-annual variations of surface POC concentrations are relatively higher during 1997 and 1998 (El Nino) than during 1999 and 2000 (La Nina) in the study area. This phenomenon is directly related to the output of Mississippi River and other major rivers, which associated with global climate change such as ENSO events. Although highest river runoff into the northern Gulf of Mexico Coast occurs in early spring and lowest flow in late summer and fall, wide-range POC plumes are observed during the summer cruises and lower concentrations and narrow dispersion of POC during the spring and fall cruises. During the summer seasons, the river discharge remarkably decreases compared to the spring, but increasing temperature causes strong stratification of the water column and increasing buoyancy in near-surface waters. Low-density plumes containing higher POC concentrations extend out over the shelf and slope with spatial patterns and controlled by the Loop Current and eddies, which dominate offshore circulation. Although river discharge is normal or abnormal during the spring and fall seasons, increasing wind stress and decreasing temperature cause vertical mixing, with higher surface POC concentrations confined to the inner shelf.

• Journal of the Earthquake Engineering Society of Korea
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• v.2 no.4
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• pp.23-30
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• 1998

During an earthquake, there are three components of excitation : horizontal excitation of the ground, vertical excitation of the pile due to superstructure feedback produced by vertical excitation of the ground, and the seawater excitation by the vertical ground shaking, that is, "the seaquake." These excitations could have effects on the pore pressure buildup mode induced in the near-field of open-ended pile and the soil plugs in open-ended pipe piles installed at offshore sites. While the ground and pile excitation could be modeled by exciting the soil and pile with simulated motions, seaquake excitation induced by the vertical ground shaking can be modeled by pulsing the water pressure at the seabed. The objectives of this study were to observe buildup trend for the porewater pressures developed in near-field of open-ended pipe pile installed in the calibration chamber during the simulated earthquake and seaquake and, also to confirm the cause for reduction of soil plugging according to pore pressure buildup. During the simulated horizontal seismic motion, there was no upward flow through soil plug because the similar magnitude of excess porewater pressure were occurred at the top and under the toe of soil plug. During the horizontal seismic motion, relatively higher hydraulic gradients caused upward flow in the soil plug and then the degradation of plugging resistance was about 20%. During seaquake, in the case of the open-ended pile installed in a deep sea with more than 220m of water depth, soil plug failed completely because of high upward hydraulic gradients through soil plug.soil plug.

• The Journal of the Acoustical Society of Korea
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• v.33 no.1
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• pp.10-20
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• 2014

To study the water-entry impact noise, on-board experiment using a small launcher firing various objects was performed in the Yellow Sea. As the launcher fires a cylindrical object from the ship vertically, generated noise is measured with a hydrophone on the starboard of Chung-hae, Marine surveyor. Three types of cylindrical objects, which have noses of flat-faced, conical, and hemisphere, were used during the experiment. The measured noise exhibits a time-dependency which can be divided into three phases: (1) initial impact phase, (2) open cavity flow phase, (3) cavity collapse and bubble oscillation phase. In most cases, the waveform of bubble oscillation phase is dominant rather than that of initial impact phase. Pinch-off time, where a cavity begins to collapse, occurs at 0.18 ~ 0.2 second and the average lasting time of bubble was 0.9 ~ 1.3 second. The energy of water-entry impact noise is focused in the frequency region lower than 100 Hz, and the generated noise is influenced by the nose shapes, object mass, and launching velocity. As a result, energy spectral density on the bubble frequency is higher in the order of flat-faced, conical, hemisphere nose, and the increase of initial energy raises the energy spectral density on the bubble frequency in the cylinder body of same shape. Finally, we compare the measurements with the simulated signals and spectrum based on the bubble explosion physics, and obtain satisfactory agreements between them.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.3
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• pp.541-547
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• 2017

In Yongwon channel, its natural flow of seawater is blocked by the construction of Busan Newport including the container berth. The channel was transformed into a narrow and long one, where it is possible that ships are only allowed to pass through the north-side channel of Gyeonmado located at the point of river mouth to Songjeongcheon. So it is considered that the changes in the terrain characteristics of Yongwon channel is likely to alter the circulation of sea water, thereby changing its water quality. Contaminants are accumulated from the sediment release. In this study, before and after dredging the sediment release test was performed. As a result, after the sediment dredging is performed, the reduction rate was higher at the same point. The results show that the water quality can be improved by dredging. Each group (A~C) reduction rate of the evaluation of the reduction rate of 4.64% T-N, 18.00%, 18.59%, respectively. T-P rate of 24.75% reduction, 24.17%, 44.08%, respectively. COD reduction rate was 18.57%, 19.76%, 38.08%, respectively. These results can be used as basic data for controlling the contamination by dredging in Yongwon channel.

• Proceedings of KOSOMES biannual meeting
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• 2006.05a
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• pp.121-128
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• 2006

The results of COD researched on August of 2004 were 6.8 ppm in North Mokpo inner Bay, 4.4 ppm in front of YongSang Bank and 4.6 ppm in front of ShinAn Beach Hotel which is over III level Marine-Environmental Standard. The other five stations sea water quality of Mokpo inner bay were reached II-III level. Concentration of total nitrogen range from 1.23 ppm to 3.56 ppm and total phosphorous was range from 0.07 ppm to 0.12 ppm which were II-III level. This results show that the Mokpo inner bay is unsuitable for aquaculture and growth of fish and for use of marine resort, it can be only available for industrial and harbour use. In results of estimated point source flow into Mokpo inner bay, the occupation ratio from YoungSang river in total inflow of TN and TP were up to 49-89 % respectively. It is indicate that in order to improve the water quality of MokPo inner bay have to control the discharge from YoungSang river first of all, then control the discharge from North Harbour domestic wastewater treatment, InAm river and NamHae domestic wastewater treatment.

• Journal of the Korean Society of Marine Environment & Safety
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• v.12 no.4 s.27
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• pp.273-283
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• 2006

The results of COD concentration on August of 2004 were 6.80 ppm in North Mokpo Inner Bay, 4.42 ppm un front of YongSang Bank and 4.60 ppm in front of ShinAn Beach Hotel which is over III level Marine Environmental Standard. The others researched five stations sea water quality of Mokpo inner bay are reached II-III level. The concentration of total nitrogen range from 1.23 ppm to 3.56 ppm and total phosphorous concentration was range from 0.07 ppm to 0.12 ppm which are to be II-III level. This results show that the Mokpo inner bay is unsuitable for aquaculture and for use of marine resort, it can be only avaliable for industrial and harbour port use. In this study, we researched 12 point source flow into Mokpo Inner bay. The rate from YoungSang river in total inflow of TN was up to 70-93 % and rate of TP was up to 31-91 % respectively. In this results, we have to control the discharge from YoungSang river first of all then control the discharge from North Harbour domestic wastewater treatment, InAm river and NamHae domestic wastewater treatment in order to improve the water quality of Mokpo Inner bay.

• Journal of Navigation and Port Research
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• v.38 no.3
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• pp.239-246
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• 2014

A study on the elution characteristics of biostimulating agents (sulfate and nitrate) from biostimulants which are used for in-situ bioremediation for the coastal sediment contaminated with organic matter was performed. The biostimulating agents were mixed with the coastal sediment, and then massed the mixture into ball. Two kinds of ball type biostimulant were prepared by coating the ball surface with two different polymers, cellulose acetate and polysulfone. A granular type biostimulant (GTB) was also prepared by impregnating a granular activated carbon in the biostimulating agent solution. The image of scanning electron microscopy for the biostimulant coated with cellulose acetate (CAB) showed that the inner side of the coating layer consisted of irregular and bigger size of pores, and the surface layer had tight structure like beehive. For the biostimulant coated with polyfulfone (PSB), the whole coating layer had a fine structure without pore. The elution rate of the biostimulating agents for the CAB was higher than that for the PSB, and the elution rate for the GTB was considerably higher than that for the PSB in distilled water as well as in sea water. The elution rate of the biostimulating agents in turbulent water flow was about 3 times higher than that in standing water, and the elution rate of nitrate was higher than that of sulfate from the stimulating agents.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.12 no.1
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• pp.39-52
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• 2000

The triad interactions have been known to be important only for shoaling waves or finite depth wind waves. In deep water, they are insignificant compared with the quadruplet interactions in respect to the evolution of wind waves due to energy transfer among the wave components. However, the triad interactions may be important even for deep water waves because they may closely be related to the wave steepness, which definitely affects wave breaking, drag of air flow over t.'Ie sea, or navigation of ships, especially during the early stage of the development of wind waves. This study reports a series of laboratory experiments, whose data are subjected to bispectral analyses to investigate the triad interactions of deep-water wind waves. It is found that the bicoherence at the spectral peak frequency and the wave steepness are almost directly proportional, indicating that the steep waves with peaked crests and flat troughs are resulted from the triad interactions. Both bicoherence and wave steepness increase with the wave age during the early stage of wave generation and then drop off as the waves grow old. It seems that the energy of the secondary spectral peak developed by the triad interactions during the early stage of wave generation is redistributed to the neighboring frequencies by the quadruplet interactions during the later stage.

• Journal of Korea Water Resources Association
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• v.55 no.3
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• pp.191-203
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• 2022

This study is a follow-up study of vulnerable areas according to the vulnerability assessment of groundwater resource management in Korea. In this study, an optimal operation plan for groundwater resource management was proposed for areas vulnerable to groundwater resource management in Korea derived from previous studies. Prior to presenting the optimal operation plan for groundwater resource management, this study grasped the current status of changes in groundwater level and seawater penetration area for vulnerable areas using MODFLOW, a groundwater flow analysis program. As a result of the analysis using basic data for 10 years from 2009 to 2018, the groundwater level fell and the sea infiltration area increased. The final purpose of this study, the optimal operation plan for groundwater resource management, was selected as a total of four alternatives that can be expected to have positive effects to increase groundwater level and reduce seawater penetration. As a result of analyzing the amount of change in groundwater level and seawater penetration by applying the selected optimal operation plan, positive effects were found in all methods. It is expected that the optimal operation plan for groundwater resource management proposed in this study will be applied not only to vulnerable areas of groundwater resources in Korea but also to areas requiring development to establish efficient groundwater resource management measures.

• Journal of the Daesoon Academy of Sciences
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• v.36
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• pp.35-78
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• 2020

This study aims to reveal the overall Fengshui figuration and geomantic features of Daesoon Jinrihoe's Geumgangsan (Mt. Geumgang) Toseong Training Temple Complex from the Hyeonggi (Energy of Form) Theory in Fengshui. This study first looked at the mountain landscape viewable from the surface, examined the influence of Qi (Energy) flowing inside it, comprehended the flow of its vitality in terms of its strengths and weaknesses, and gauged the depth of the energy produced from mountain streams to determine fortune and misfortune. There is a special significance to this site due to Sangje's teaching that "⋯ it will be prosperous with 12,000 Dotonggunja (Dao-empowered Sages)," and it is also known as a efficacious grounds for cultivation among ascetics due to it housing the royal mausoleum of Dojeon (interpreted by some as Maitreya). Concerning this, this study explores the geomantic symbolism and growth-supporting land of Geumgangsan Toseong Training Temple Complex as it corresponds to Fengshui theory, and in keeping with this, the topography and conditions are likewise examined. The mountain range and its energy pathways (veins) harmonize with the pure water energy coming from the East Sea. The mountain terrain of Mount Geumgang, and the geomantic location, topography, and energy pathways that influence Daesoon Jinrihoe Geumgangsan Toseong Training Temple Complex are all explored. The Baekdudaegan Mountain Range extends through Mount Geumgang to Sinseonbong Peak, and one range extends to Geumgangsan Toseong Training Temple Complex whereas the other range extends through Sangbong Peak down to Misiryeong Valley and Mount Seorak. Thus, this study demonstrates that Daesoon Jinrihoe has always strongly considered the relationship between its temple complexes and their surrounding environment. The order has always selected locations that exhibit optimal conditions which suit the construction of sacred spaces. The determinations in this paper were made through an academic approach that drew upon various theories of Fengshui while examining Daesoon Jinrihoe's Geumgangsan Toseong Training Temple Complex. The in-depth analysis was specifically based on Hyeonggi Fengshui. At the same time, this study also looked into the surroundings of Geumgangsan Toseong Training Temple Complex. In particular, the mountains and flow of nearby bodies of water were comprehensively examined to show how the surrounding topography corresponds to the principles of Fengshui. An integral approach combining all major theories of Fengshui revealed that Geumgangsan Toseong Training Temple Complex starts from Sinseonbong Peak, and its energy flows through the main mountain range, going through numerous geographical changes of yin and yang. When the range flows down, the water flows accordingly, and where the water whirls, the mountains are shaped accordingly. Eventually, this energy reaches Geumgangsan Toseong Training Temple Complex. From the organic relationship between mountains and bodies of water, which can be said to be the essence of the order of nature, it can be judged that the most prominent geomantic feature of Geumgangsan Toseong Training Temple Complex corresponds to traditional theories of Fengshui in that it forms a configuration wherein optimal water energy supports the Virtuous Concordance of Yin Yang and harmonizes the Blue Dragon with the White Tiger.