• Ocean and Polar Research
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• v.32 no.3
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• pp.309-319
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• 2010

To assess community structure and diversity of archaea, a clone sequencing analysis based on an archaeal 16S rRNA gene was conducted at three sediment depths of the continental slope and Ulleung Basin in the East Sea. A total of 311 and 342 clones were sequenced at the slope and basin sites, respectively. Marine Group I, which is known as the ammonia oxidizers, appeared to predominate in the surface sediment of both sites (97.3% at slope, 88.5% at basin). In the anoxic subsurface sediment of the slope and basin, the predominant archaeal group differed noticeably. Marine Benthic Group B dominated in the subsurface sediment of the slope. Marine Benthic Group D and Miscellaneous Crenarchaeotal Group were the second largest archaeal group at 8-9 cm and 18-19 cm depth, respectively. Marine Benthic Group C of Crenarchaeota occupied the highest proportion by accounting for more than 60% of total clones in the subsurface sediments of the basin site. While archaeal groups that use metal oxide as an electron acceptor were relatively more abundant at the basin sites with manganese (Mn) oxide-enriched surface sediment, archaeal groups related to the sulfur cycle were more abundant in the sulfidogenic sediments of the slope. Overall results indicate that archaeal communities in the Ulleung Basin show clear spatial variation with depth and sites according to geochemical properties the sediment. Archaeal communities also seem to play a significant role in the biogeochemical carbon (C), nitrogen (N), sulfur (S), and metal cycles at each site.

• Ocean and Polar Research
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• v.42 no.1
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• pp.89-95
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• 2020

Our study was conducted to examine the nest attendance of the Black-faced Spoonbill (Platalea minor) from 2015 to 2018 at two Islets located in Incheon, South Korea. We visited study sites in March-April and set up the remote sensor cameras at two breeding sites (Mae-do, Guji-do) to observe chick-rearing behavior. Mean nest bout length at Mae-do (female: 4.2 ± 0.1 hr, male: 4.0 ± 0.1 hr) was shorter than at Guji-do (female: 5.3 ± 0.2, male: 6.0 ± 0.3 hr), and trip duration at Mae-do (female: 4.4 ± 0.1 hr, male: 4.0 ± 0.1) was also shorter than at Guji-do (female: 7.0 ± 0.2 hr, male: 7.0 ± 0.3). Mean nest bout length and trip duration at both study sites decreased as chick rearing progressed. Males attended their nests during the daytime, and females attended their nests during the nighttime. Our results showed that females and males' duties were divided by the diel cycle, but the pattern of nest attendance could change depending on the environment of their breeding sites during the chick-rearing period.

• Ocean and Polar Research
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• v.37 no.1
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• pp.81-90
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• 2015

International Seabed Authority (ISA) is currently developing rules with regard to exploitation of manganese nodules which will be contained in its first regulations governing the exploitation of deep seabed mineral resources. A stakeholder survey was conducted in the early 2014 by ISA with the aim of facilitating participation of interested entities in the development process of the rules. The stakeholders who had replied to the survey included existing contractors, sponsoring States, environmentalists, academics, and nongovernmental organizations. Opinions given by them largely reflect their own interests. This paper aims to clarify the scope of the obligations regarding the environmental protection which may be imposed on contractors under the new regulations for the exploitation of manganese nodules. To do so, it first analyses the express provisions on environmental protection applicable to deep seabed mining included in the Law of the Sea Convention, its agreement on implementation of Part XI, and the regulations on exploration for manganese nodules. Secondly, it categorizes these obligations based on the categories of international obligations suggested by Combacau and Alland. Based on the categorizations this paper concludes that, in addition to the existing duties to protect deep seabed environment within the Law of the Sea Convention system, the following new obligations could be added: conservation of exploitation sites for a limited time after the contract is ceased; taking all necessary measures for rehabilitation of destroyed ecosystems that occurredas a result of mining activities; monitoring exploitation sites for a limited period time after the contract is ceased; observing rules and standards on safety of ships and environmental protection adopted under IMO instruments; regulation on the discharge of mine tailings from the facilities used for exploitation of deep sea minerals. Lastly, this paper attempts to provide ways of reflecting national interests in terms of potential obligations which may be included in the new regulations.

• Economic and Environmental Geology
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• v.29 no.5
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• pp.575-587
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• 1996

The purpose of this study is to develop geostatistical methods for selection of prospective areas of polymetallic nodule deposits in KODOS (Korea Deep Ocean Study) area of the North-East Pacific Ocean. In this study $110{\times}165$ grid system was used, and each node represents the center of an estimated block of $1km{\times}1km$. The ordinary kriging was applied to SeaBeam2000 data in order to evaluate the bathymetry. A structural analysis (variogram) of the bathymetry data was carried out for constructing digital terrain model (DTM) and the maximum slopes of the bathymetry were calculated by DTM data. The above method can be used to solve the problem that is resulted from the lack of theory of a change of support model for the maximum slope of the bathymetry. The ordinary kriging and the indicator kriging were used to evaluate the nodule abundance, and the different two kriging methods were compared to evaluate the accuracy for the estimation of the nodule abundance. It has been shown that indicator kriging was better estimation tool than the ordinary kriging. The overlay map is presented for the selection of potentially minable sites by combining the two indicator maps of the nodule abundance and the maximum slope of bathymetry. This overlay map could be utilized to establish follow-up survey and to investigate the potentially minable sites in the KODOS area.

• Journal of the korean society of oceanography
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• v.31 no.3
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• pp.134-143
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• 1996

Sediment cores were collected from one site each in Amursky and Ussuriysky Bays in the Peter the great Bay for $^{210}Pb$, org C, N, biogenic Si, ${\delta}^{13}$C and ${\delta}^{15}$N analysis to elucidate the processes of biogenic particulate matter accumulation and early diagenetic change in the upper sediment column. Biogeochemistry at the core sites of both bays shows differences in sedimentation rate, sediment mixing, and diagenetic processes of particulate biogenic matter. Sedimentary organic matter at the core sites in both bays appeared to be largely derived from marine origin. Sedimentation rates are 173 and 118 mg $cm^{-2}$ $yr^{-1}$(0.13 and 0.11 cm $yr^{-1}$) in Amursky and Ussuriysky Bays, respectively. The surface mixed layer in the core top was present in Amursky Bay but not in Ussuriysky Bay. At the core site in Amursky Bay, incorporation of biogenic particulate matter into the sediment from the overlying waters is 236, 19, 142 mmol $cm^{-2}$ $yr^{-1}$ for organic C, N, and biogenic Si, respectively. Of which about 70${\%}$ of organic C and biogenic Si are degraded within the upper 25 cm sediment and the rest are buried at 25 cm sediment horizon. At the core site in Ussuriysky Bay, incorporation of biogenic particulate matter into the sediment from overlying waters is 164, 18, 76 mmol $cm^{-2}$ $yr^{-1}$ for organic C, N, and biogenic Si, respectively. Of which less than 50${\%}$ of organic C and biogenic Si are degraded within the upper 25 cm sediment and the remainder are buried at 25 cm sediment horizon. This large difference of degradation of biogenic matter in the upper 25 cm sediment column appears to be resulted from the difference in sediment mixing rates between the two cores.

• Journal of Ocean Engineering and Technology
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• v.34 no.5
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• pp.351-360
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• 2020

Of late, demand for test sites for marine equipment such as ASV, AUV, ROV, and various underwater sensors is increasing. The authors have focused on an oscillating water column (OWC), which is being constructed near Chagwido Island Jeju, as one of the test-sites. The main objective of the OWC is to produce wave energy and develop technologies. It has been built in the sea approximately 1 km off the coast. It has berth accommodation and some rooms that can be used as laboratories. To investigate the feasibility of its usage as a test site for marine equipment, we acquired bathymetric data around the OWC by using a multi-beam echo sounder and a single-beam scanning sonar. The accessibility of the OWC from nearby ports and the use of support vessels or ships were also investigated. 3D point cloud data from the multi-beam echo sounder and 2D acoustic images from the scanning sonar are expected to be used as references for identifying changes over time. In addition, through these experiments, we derived a procedure to use this facility as a test site by using the IDEF0 functional modelling method. Based on this preliminary investigation and previously reported examples, we determined the general conditions and preferences for evaluating the performance of various marine equipment heuristically. Finally, we developed five applications that were derived from this investigation.

• Ocean and Polar Research
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• v.43 no.4
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• pp.295-306
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• 2021

A field scale productivity analysis is required for the development of gas hydrate in marine sedimentary layers to verify the field applicability of production techniques and to improve productivity. In this study, the productivity resulting from the application of depressurization using multi-wells for the development of gas hydrate in the Ulleung Basin, East Sea of Korea, was determined. A numerical analysis model reflecting the conditions of candidate sites for the Ulleung Basin was constructed, and the productivity and dissociation behavior were comparatively analyzed. The pressure propagation and gas hydrate dissociation region by the multi-wells were wider and the productivity was higher than that of a single well. Different depressurization effects according to the spacing of multi-wells affected productivity. The results provide basic data for productivity analysis when establishing a field test production plan for the Ulleung Basin.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.6
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• pp.437-445
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• 2010

There is increasing interest, on the global basis, in the operation of ocean surface radars for measurement of coastal sea surface conditions to support environmental, oceanographic, meteorological, climatological, maritime and disaster mitigation operations. In south Korea, ocean surface radars are operating to monitoring oil spill, outflow from dike or preventing from safety-accidents in the 6 regions (16 radial sites) by main frequency about 13, 25 and 42 MHz until the present. However, that ocean surface radars have been operated on an experimental spectrum basis. In the results of 3~50 MHz band domestic analysis to improve the regulatory status of the spectrum used by oceanographic radars, it was demonstrated that sufficient frequency bands are available for oceanographic radars on the frequency band above 20 MHz. It is difficult to deploy and operate oceanographic radars in the sub-bands below 20 MHz except for 13 MHz band. For using HF ocean surface radars one should understand the spectrum environment in Korea and should prepare a suitable operating system and data processing techniques.

• Korean Journal of Agricultural and Forest Meteorology
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• v.12 no.4
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• pp.217-224
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• 2010

This study was carried out to quantify potential effects of the surrounding ocean on the observed air temperature at coastal weather stations in the Korean Peninsula. Daily maximum and minimum temperature data for 2001-2009 were collected from 66 Korea Meteorological Administration (KMA) stations and the monthly averages were calculated for further analyses. Monthly data from 27 inland sites were used to generate a gridded temperature surface for the whole Peninsula based on an inverse distance weighting and the local temperature at the remaining 39 sites were estimated by recent techniques in geospatial climatology which are widely used in correction of small - scale climate controls like cold air drainage, urban heat island, topography as well as elevation. Deviations from the observed temperature were regarded as the 'apparent' sea effect and showed a quasi-logarithmic relationship with the distance of each site from the nearest coastline. Potential effects of the sea on daily temperature might exceed $6.0^{\circ}C$ cooling in summer and $6.5^{\circ}C$ warming in winter according to this relationship. We classified 25 sites within the 10 km distance from the nearest coastline into 'coastal sites' and the remaining 15 'fringe sites'. When the average deviations of the fringe sites ($0.5^{\circ}C$ for daily maximum and $1.0^{\circ}C$ for daily minimum temperature) were used as the 'noise' and subtracted from the 'apparent' sea effects of the coastal sites, maximum cooling effects of the sea were identified as $1.5^{\circ}C$ on the west coast and $3.0^{\circ}C$ on the east and the south coast in summer months. The warming effects of the sea in winter ranged from $1.0^{\circ}C$ on the west and $3.5^{\circ}C$ on the south and east coasts.

• Journal of Microbiology and Biotechnology
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• v.32 no.4
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• pp.504-513
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• 2022

Chitin deacetylase (CDA) inhibitors were developed as novel antifungal agents because CDA participates in critical fungal physiological and metabolic processes and increases virulence in soil-borne fungal pathogens. However, few CDA inhibitors have been reported. In this study, 150 candidate CDA inhibitors were selected from the commercial Chemdiv compound library through structure-based virtual screening. The top-ranked 25 compounds were further evaluated for biological activity. The compound J075-4187 had an IC50 of 4.24 ± 0.16 µM for AnCDA. Molecular docking calculations predicted that compound J075-4187 binds to the amino acid residues, including active sites (H101, D48). Furthermore, compound J075-4187 inhibited food spoilage fungi and plant pathogenic fungi, with minimum inhibitory concentration (MIC) at 260 ㎍/ml and minimum fungicidal concentration (MFC) at 520 ㎍/ml. Therefore, compound J075-4187 is a good candidate for use in developing antifungal agents for fungi control.