• Journal of Korean Society for Quality Management
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• v.47 no.1
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• pp.139-150
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• 2019

Purpose: LST-II is a special naval ship to carry out landing operations by transporting tanks, armored vehicles and military vehicles. Bad weather, maximum wave height of 4-5 m, caused damage to the LCM cradles while the LST-II No.O ship was moving to Thailand for training in February 2016. Methods: Based on the results of the field check, DTaQ conducted a study on the causes analysis and improvement measures. Results: The improvement plan that was derived was verified through a structural analysis and the improvement plan was applied to the follow-up ships. Conclusion: The improvement of LCM cradle has increased the safety of the crew and landing forces, and improved the operational efficiency.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.33-43
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• 2019

A comparison between sea trial measurements and full-scale CFD results is presented for two self-propelled ships. Two ships considered in the present study are: a general cargo carrier at Froude number $F_n=0:182$ and a car carrier at $F_n=0:254$. For the general cargo carrier, the propeller rotation rate is fixed and the achieved speed and trim are compared to sea trials, while for the car carrier, the propeller rotation rate is adjusted to achieve the 80% MCR. In addition, three grids are used for each ship in order to assess the grid refinement sensitivity. All simulations are performed using the Naval Hydro pack based on foam-extend, a community driven fork of the OpenFOAM software. The results demonstrate the possibility of using high-fidelity numerical methods to directly calculate ship scale flow characteristics, including the effects of free surface, non-linearity, turbulence and the interaction between propeller, hull and the flow field.

• Journal of Navigation and Port Research
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• v.45 no.5
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• pp.231-237
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• 2021

Enhancing the performance of maritime wireless communication has been highlighted by the issue of cell planning in the sea area because of lack of an appropriate Propagation Loss Model (PLM). To resolve the cell planning issue in vast sea areas, it was essential to develop the (PLM) matching the intended sea area. However, there were considerable gaps between the prediction of legacy PLMs and field measurement in propagation loss and there was a need to develop the adjusted PLM (A-PLM). Therefore, cell planning was performed on this adjusted model, including modification of the base station's location, altitude, and antenna azimuth to meet the quality objectives. Furthermore, in order to verify the availability of the cell planning, Communication Service Quality Monitoring System (CS-QMS) was developed in the LTE-Maritime project to collect LTE signal quality information from the onboard equipment at regular intervals and to ensure that the service quality was high enough to satisfy the goals in each designated grid. As a result of verification, the success rate of RSRP was 95.7% for the intensive management zone (IMZ) and 96.4% for the interested zone (IZ), respectively.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.38 no.3
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• pp.241-248
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• 2002

The combined hydroacoustic and demersal trawl surveys to investigate the distribution characteristics of fish schools in the Yellow Sea and the East China Sea were carried out during the spring of 1997 by the training ship "Nagasaki Maru" of Nagasaki University. Fish samples were collected by bottom trawling from 9 trawl stations randomly selected in the survey area, and the species and length compositions of trawl catches are examined. Hydroacoustic data were collected by using a Furuno FQ-50 scientific echo sounder operating at 50KHz and the data stored in field were later processed in the laboratory. The results obtained can be summarized as follows ：1. In the 9 trawl surveys conducted in the Yellow Sea and the East China Sea, 78 species including 80 species of fishes, 4 species of Cephalopoda and 6 species of Crustacea, were identified. The most abundant species in these stations were swimming crab(Portunus trituberculatus), Japanese horse mackere(Trachurus japonicus), redlip croaker(Larimichthys polyactis) and the catch per one hour in each station ranged 7.7 to 182.5 kg/hour. 2. The mean volume backscattering strength for the entire water column and the bottom layer of the 0-10 m from bottom friction were -74.6 ㏈ and -68.2 ㏈, respectively. That is, the mean volume backscattering strength for the bottom layer was 6.4 ㏈ higher than that for the entire water column 3. In the surveys during the spring of 1997, the geographical distribution characteristics of fish schools suggests a trend of decreasing fish abundance toward the coast area of Korea and the highest demersal concentrations appeared in waters between the Cheju Island and the Tsushima Island 4. The distribution density of fish school in the East China Sea and Yellow Sea during the 1997 acoustic survey were estimated to be 6.65$\times$10$^{-5}$ kg/㎥ in the entire water column and 2.86$\times$l0$^{-4}$ kg/㎥ in the bottom layer, respectively.pectively.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.29 no.2
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• pp.123-131
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• 2011

Characteristics of sea surface temperature(SST) difference around Gwang-Yang steel Mill where can affect marine ecosystem in Gwang-Yang bay using 25 collected Landsat-7 ETM+ thermal infrared band data from 2000 to 2010. To analyze accuracy of SST from the Landsat-7 ETM+ thermal infrared image， satellite-induced SST was verfied by compared Yeo-Su tide station and Landsat thermal image. As a result, SST from Landsat-7 ETM+ is $1.22^{\circ}C$ lower than sea temperature from Yeo-Su tide station and correlation coefficient resulted in above 0.991 which means that correlation coefficient between Landsat image temperature and field sea temperature is relatively high. Five regions were selected to analyze sea surface temperature between near Gwang-Yang steel mill and the open sea and analyzed timeseries of sea surface temperature seasonally and regionally. Moreover, the additional analysis has been carried out by comparing the averaged temperatures of Gwang-Yang and Soon-Cheon bays using the dataset over a year.

• Ocean and Polar Research
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• v.25 no.spc3
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• pp.361-371
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• 2003

The effect of bottom friction on the steady wind-driven circulation in the Yellow Sea and the East China Sea (YSECS) has been studied using a two-dimensional numerical model with and without tidal forcing. Upwind flow experiment in YSECS has also been carried out with a schematic time variation in the wind field. The surface water setup and circulation pattern due to steady wind forcing are found to be very sensitive to the bottom friction. When the effects of tidal currents are neglected, the overall current velocities are overestimated and eddies of various sizes appear, upwind flow is formed within the deep trough of the Yellow Sea, forming a part of the topographic gyre on the side of Korea. When tidal forcing is taken into account, the wind-induced surface elevations are smoothed out due to the strong tide-induced bottom friction, which is aligned almost normal to the wind stresses; weak upwind flow is farmed in the deep trough of the Yellow Sea, west and south of Jeju. Calculation with wind forcing only through a parameterized linear bottom friction produces almost same results from the calculation with $M_2$ tidal forcing and wind forcing using a quadratic bottom friction, supporting Hunter (1975)'s linearization of bottom friction which includes the effect of tidal current, can be applied to the simulation of wind-driven circulation in YSECS. The results show that steady wind forcing is not a dominant factor to the winter-time upwind flow in YSECS. Upwind flow experiment which considers the relaxation of pressure gradient (Huesh et al. 1986) shows that 1) a downwind flow is dominant over the whole YSECS when the northerly wind reaches a maximum speed; 2) a trend of upwind flow near the trough is found during relaxation when the wind abates; 3) a northward flow dominates over the YSECS after the wind stops. The results also show that the upwind flow in the trough of Yellow Sea is forced by a wind-induced longitudinal surface elevation gradient.

• Korean Journal of Remote Sensing
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• v.23 no.4
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• pp.311-321
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• 2007

The diffuse attenuation coefficient for down-welling irradiance $K_d({\lambda})$, which is the propagation of down-welling irradiance at wavelength ${\lambda}$ from surface to a depth (z) in the ocean, and underwater visibility are important optical parameters for ocean studies. There have been several studies on $K_d({\lambda})$ and underwater visibility around the world, but only a few studies have focused on these properties in the Korean sea. Therefore, in the present study, we studied $K_d({\lambda})$ and underwater visibility around the coastal area of the Yellow Sea, and developed $K_d({\lambda})$ and underwater visibility algorithms for ocean color satellite sensor. For this research we conducted a field campaign around the Yellow Sea from $19{\sim}22$ September, 2006 and there we obtained a set of ocean optical and environmental data. From these datasets the $K_d({\lambda})$ and underwater visibility algorithms were empirically derived and compared with the existing NASA SeaWiFS $K_d({\lambda})$ algorithm and NRL (Naval Research Laboratory) underwater visibility algorithm. Such comparisons over a turbid area showed small difference in the $K_d({\lambda})$ algorithm and constants of our result for underwater visibility algorithm showed slightly higher values.

• Journal of The Korean Society of Integrative Medicine
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• v.10 no.4
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• pp.121-136
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• 2022

Purpose : Marine therapy is an activity that promotes public health such as constitution improvement, immunity improvement, and anti-aging by utilizing marine therapeutic resources such as seawater, mud, seaweed, salt and sea climate. In Europe developed countries, the marine therapy industry has been developing for centuries, with France, Germany, and Israel leading the way. Currently, it has achieved great industrial achievements and is of great help in improving the human health. The purpose of this study is to investigate how marine therapeutic resources benefit to human health, as well as how to study and utilize their efficacy. We analyzed previous research articles related to the effects of marine therapeutic resources. Methods : The study included a total of 830 published literatures in the last 20 years from the Republic of Korea and other contries. PubMed and Google Scholar were utilized to collect the foreign source while the local scientific publications were accessed through the Korean Education and research Information Service (KERIS) and Korean studies Information Service System (KISS). The keywords used to search foreign literature were "marine therapy", "Thalassotherapy", "seawater", "deep seawater", "saline groundwater", "sand therapy", "mud therapy", "hydrotherapy", "seaweed", "Sun light", "sea salt", "marine animal", and "marine microorganisms" were combined, and for the domestic literature, the keywords were "marine therapy", "marine therapeutic resources", "seawater", and "sand". Results : A total of 830 research papers were found as a result of searching for domestic and international papers related to marine therapeutic resources. The collected documents were classified into 175 seawater resources, 259 marine mineral resources, 41 marine environment, and 355 marine organisms. The efficacy of each marine therapeutic resources was analyzed. By resources type, there were about 213 papers on the efficacy of seaweed, followed by about 175 papers on seawater, 142 on microorganisms, 124 on mud/peat, and sand, salt, minerals and others are appeared in order (Table 1). Conclusion : Korea has the highest marine biodiversity index, excellent tidal flats, four distinct seasons, and various sea environments of the East sea, Yellow sea, South sea and Jeju sea. For this reason, Korea has a much more diverse marine therapeutic resources than other advanced countries in the marine therapy industry. prebiously, we thought that the sea was only valuable as a shipping port and fishery industry. But now, it been shown that the ocean can become a new industrial field which can contribute to human health and well-being by providing healing and therapy to people through the gift of marine resources.

• Journal of Environmental Science International
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• v.6 no.5
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• pp.437-449
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• 1997

To predict diffusion and movement of k pollutants In coastal urban region a numerical simulation shouts be consider atmospheric flow field with land-sea breeze, mountain-valley wand and urban effects. In this study we used Lagrangian [article dispersion method In the atmospheric flow field of Pusan coastal region to depict diffusion and movement of the Pollutants emoted from particular sources and employed two grid system, one for large scale calculating region with the coarse mesh grid (CMG) and the other for the small region with the One mesh 914 (FMG). It was found that the dispersion pattern of the pollutants followed local circulation system in coastal urban area and wale air pollutants exhausted from Sasang moved Into Baekyang and Jang moutain, air pollutants from Janglim moved into Hwameong-dong region.

• 한국신재생에너지학회:학술대회논문집
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• 2007.06a
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• pp.630-634
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• 2007

In the past, the use of wave energy has mainly been focused on conversion of large wave energy resources in the far offshore areas. However, with the technological improvement of converting wave energy into electricity, the energy resources at much shallow waters are now considered as a site for possible installation of the devices that obtain energy from the waves. In this respect, the wave energy resources on the east coast of Korea, where the sea is milder than the open ocean, were investigated using the field measurement data obtained at three different locations along the coast. For all the locations, the wave power was greater in winter season, compared to summer season. The estimated wave power varied from 2 to 4.5 kW/m on average, depending on the measurement locations.