• Journal of Ocean Engineering and Technology
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• v.35 no.6
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• pp.446-456
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• 2021

To build an environment facility of a large-scale ocean basin, various detailed reviews are required, but it is difficult to find data that introduces the related research or construction processes on the environment facility. The current generator facility for offshore structure safety evaluation tests should be implemented by rotating the water of the basin. However, when the water in the large basin rotates, relatively large flow irregularities may occur and the uniformity may not be adequate. In this paper, design and review were conducted to satisfy the performance goals of the DOEB through computational numerical analysis on the shape of the waterway and the flow straightening devices to form the current in the large tank. Based on this, the head loss, which decreases the flow rate when the large tank water rotates through the water channel, was estimated and used as the pump capacity (impeller) design data. The impeller of the DOEB current generator was designed through computational numerical analysis (CFD) based on the lift surface theory from the axial-type impeller shape for satisfying the head loss of the waterway and maximum current velocity. In order to confirm the performance of the designed impeller system, the flow rate and flow velocity performance were checked through factory test operation. And, after installing DOEB, the current flow rate and velocity performance were reviewed compare with the original design target values. Finally, by measuring the current velocity of the test area in DOEB formed through the current generator, the spatial current distribution characteristics in the test area were analyzed. Through the analysis of the current distribution characteristics of the DOEB test area, it was confirmed that the realization of the maximum current velocity and the average flow velocity distribution, the main performance goals in the waterway design process, were satisfied.

• Journal of the Korean Society for Marine Environment & Energy
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• v.17 no.3
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• pp.236-246
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• 2014

Deep Sea Water (DSW) has recently drawn attention due to the considerable benefits provided by low-temperature, various minerals included, purity and safety of the water resource. Since Korean DSW-industry initiated exploitation of the alternative water resource in 2008, it merely took off, but remains in the infant stage. It is mainly because the industry has only focused on production of drinkable bottled water, and failed to improve sustainability and competitiveness. On the contrary, not a few oversea DSW industries (e.g. Japanese and Taiwanese DSW industries) have successfully cultivated their markets, and have become leading cases of the industry. The common success factors learned from the cases are as follows; 1) They continuously invest on technology innovation, introduce new DSW-based products, and increase the usability of DSW in various areas of products and services, and 2) they strategically focus on high value-added products rather than just bottled water products. This paper examines the cases of the advanced DSW industries and analyzes patent data and their technology-based development strategies.

• Proceedings of KOSOMES biannual meeting
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• 2004.11a
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• pp.117-122
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• 2004

In order to investigate the initial stage of deep water formation between Vladivostok and the subpolar front in the East Sea, the factors, temperature, salinity, dissolved oxygen, measured by multi-ship surveys in 1969 have been used Deep water formation in the East Sea occurs in essentially two different forms: near continent and open ocean formation the position of eddy derived from potential vorticity matches well with that of deep water formation. The vertical and horizontal distributions of potential vorticity, geostrophic current, temperature, salinity and dissolved oxygen give clues for the preconditioning phase of open ocean formation like a doming of isotherm, associated with a cyclonic circulation

• Korean Journal of Fisheries and Aquatic Sciences
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• v.38 no.1
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• pp.65-69
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• 2005

We have developed a new method of manufacturing salts by horizontal spray drying technique, using the concentrated deep ocean water after desalination processes. We studied the chemical characteristics of the spray-dried salts. Sodium content in the spray salts is $28.4\%$, which is $10-30\%$ lower than that of bay salts, bamboo salts and boiling salts $(32-38.2\%)$. However, the contents of magnesium, potassium and calcium of the spray salts are 2.5 times, 3 times and 4.5 times higher relative to those of bay salts, respectively. On the one hand, sulfur content in spray salts is 14 times lower than those of bay salts, which is caused by their volatilization during spray and vaporization of the concentrated seawater. Enrichment factors of Mg (0.8), K (0.9) and Ca (1.0) in the spray salts are relatively higher than those in bay salt (0.2-0.3), bamboo salt (0.15-0.4) and boiled salt (0.4-0.7), respectively. On the contrary, enrichment factor of sulfur in spray salts is observed to be 0.07, which is considerably lower than those in other salts (0.3-0.7). It means that the minerals like Mg, K and Ca can be well conserved from seawater to salts through spray drying techniques, while volatile elements like sulfur, lead, mercury and organic compounds can be easily removed from seawater via spray and heating processes.

• Journal of Ocean Engineering and Technology
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• v.20 no.6 s.73
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• pp.75-81
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• 2006

In this study, the dynamic response of the umbilical cable in a deep-water unmanned underwater vehicle system was analyzed. In order to analyze the forces acting on the cable, the launcher and umbilical cable were modeled by the simple 1-D mass-spring system. Damping and dynamic analysis was carried out by a direct time integration scheme using the $Newmark-{\beta}$ method with inverse iteration procedure, considering the nonlinear drag forces acting on the launcher. The obtained results of the present study can be used for the design of connecting the structure of the launcher and cable of the UUV system.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.223-225
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• 2006

In this study, the graphite/epoxy prepregs were surface-treated using oxygen plasma, and optimal treatment time was determined measuring the contact angle en the prepreg surface. Interlaminar fracture behavior of surface-treated graphite/epoxy composite was compared with that of regular (untreated) graphite/epoxy composites. The results showed that the contact angle was a minimum when treated for 30 minutes. The interlaminar fracture toughness of surface-treated specimen was improved about 15% compared with that of regular specimen.

• Ocean and Polar Research
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• v.32 no.1
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• pp.15-22
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• 2010

Calcium carbonate ($CaCO_3$) content was measured from 3 box core (BC060301, BC060303, BC070301) sediments, in addition to pilot core (PC313) sediments, from deep waters within the Western Pacific Ocean. At the two collection sites (BC060301, PC313) located close to the equator, downcore variation exhibited low $CaCO_3$ content during the interglacial period and high $CaCO_3$ content during the glacial period. Variation of coarse fraction (>$63\;{\mu}m$) content also followed changes in $CaCO_3$ content, indicating that dissolution effect of bottom water decreased during the glacial period. Such variation pattern is typical of the Pacific Ocean. However, downcore variation at the two collection sites (BC060303, BC070301) in the Philippine Sea contrasted the trend of the previous two cores (i.e., high $CaCO_3$ content during the interglacial period and low during the glacial period). This pattern is typical of the Atlantic Ocean. Such results may be attributed to the increasing dilution effect, initiated possibly by the increased transportation of terrigenous materials from nearby continent and archipelago during the glacial period when sea level was low. Alternatively, it is possible that the non-carbonate biogenic particles may have been responsible for dilution. Because of these uncertainties, the record of $CaCO_3$ variation in the deep Western Pacific Ocean is not regionally consistent.

• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.28 no.1
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• pp.1-18
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• 2023

The East Sea, one of the regions where the most rapid warming is occurring, is known to have important implications for the response of the ocean to future climate changes because it not only reacts sensitively to climate change but also has a much shorter turnover time (hundreds of years) than the ocean (thousands of years). However, the processes underlying changes in seawater characteristics at the sea's deep and abyssal layers, and meridional overturning circulation have recently been examined only after international cooperative observation programs for the entire sea allowed in-situ data in a necessary resolution and accuracy along with recent improvement in numerical modeling. In this review, previous studies on the physical characteristics of seawater at deeper parts of the East Sea, and meridional overturning circulation are summarized to identify any remaining issues. The seawater below a depth of several hundreds of meters in the East Sea has been identified as the Japan Sea Proper Water (East Sea Proper Water) due to its homogeneous physical properties of a water temperature below 1℃ and practical salinity values ranging from 34.0 to 34.1. However, vertically high-resolution salinity and dissolved oxygen observations since the 1990s enabled us to separate the water into at least three different water masses (central water, CW; deep water, DW; bottom water, BW). Recent studies have shown that the physical characteristics and boundaries between the three water masses are not constant over time, but have significantly varied over the last few decades in association with time-varying water formation processes, such as convection processes (deep slope convection and open-ocean deep convection) that are linked to the re-circulation of the Tsushima Warm Current, ocean-atmosphere heat and freshwater exchanges, and sea-ice formation in the northern part of the East Sea. The CW, DW, and BW were found to be transported horizontally from the Japan Basin to the Ulleung Basin, from the Ulleung Basin to the Yamato Basin, and from the Yamato Basin to the Japan Basin, respectively, rotating counterclockwise with a shallow depth on the right of its path (consistent with the bottom topographic control of fluid in a rotating Earth). This horizontal deep circulation is a part of the sea's meridional overturning circulation that has undergone changes in the path and intensity. Yet, the linkages between upper and deeper circulation and between the horizontal and meridional overturning circulation are not well understood. Through this review, the remaining issues to be addressed in the future were identified. These issues included a connection between the changing properties of CW, DW, and BW, and their horizontal and overturning circulations; the linkage of deep and abyssal circulations to the upper circulation, including upper water transport from and into the Western Pacific Ocean; and processes underlying the temporal variability in the path and intensity of CW, DW, and BW.

• Proceedings of the Korean Society of Coastal and Ocean Engineers Conference
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• 2006.09a
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• pp.177-180
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• 2006

• Journal of Ocean Engineering and Technology
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• v.36 no.2
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• pp.101-107
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• 2022

Dean (1965) proposed the use of the root mean square error (RMSE) in the dynamic free surface boundary condition (DFSBC) and kinematic free-surface boundary condition (KFSBC) as an error evaluation criterion for wave theories. There are well known wave theories with RMSE more than 1%, such as Airy theory, Stokes theory, Dean's stream function theory, Fenton's theory, and trochodial theory for deep-water waves. However, none of them can be applied for deep-water breaking waves. The purpose of this study is to provide a closed-form solution for deep-water waves with RMSE less than 1% even for breaking waves. This study is based on a previous study (Shin, 2016), and all flow fields were simplified for deep-water waves. For a closed-form solution, all Fourier series coefficients and all related parameters are presented with Newton's polynomials, which were determined by curve fitting data (Shin, 2016). For verification, a wave in Miche's limit was calculated, and, the profiles, velocities, and the accelerations were compared with those of 5^th-order Stokes theory. The results give greater velocities and acceleration than 5^th-order Stokes theory, and the wavelength depends on the wave height. The results satisfy the Laplace equation, bottom boundary condition (BBC), and KFSBC, while Stokes theory satisfies only the Laplace equation and BBC. RMSE in DFSBC less than 7.25×10^-2% was obtained. The series order of the proposed method is three, but the series order of 5^th-order Stokes theory is five. Nevertheless, this study provides less RMSE than 5^th-order Stokes theory. As a result, the method is suitable for offshore structural design.