• Journal of Microbiology and Biotechnology
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• v.14 no.5
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• pp.952-958
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• 2004

Of 23 psychrotrophic bacteria isolated from the west Pacific deep-sea sediments, 19 were assigned to the $\gamma$-Proteobacteria, 3 to the <$\beta$-Proteobacteria, and 1 to the Gram-positive bacteria, as determined by their 16S rDNA sequences. Ten psychrotrophs, affiliated to the Psychrobacter, Pseudoalteromonas, and Pseudomonas genera in the $\gamma$-Proteobacteria group, were screened for lipolytic bacteria. The majority of the lipolytic isolates had growth temperatures between 4-$30^\circ{C}$, and all of them were neutrophilic, aerobic, or facultatively anaerobic, and some were able to produce multiple kinds of ectohydrolytic enzymes. The deep-sea strains Psychrobacter sp. wp37 and Pseudoalteromonas sp. wp27 were chosen for further lipase production analysis. Both strains had the highest lipase production when grown at 10 to $20^\circ{C}$; their highest lipase production occurred at the late-exponential growth stage; and the majority of the enzymes were excreted to the outside of the cells. Lipases from both strains had the same optimal reaction temperature and pH (20-$30^\circ{C}$, pH 7-8) and could retain about 60% of their highest activity at $4^\circ{C}$. Furthermore, SDS-PAGE and an in-gel activity test showed that they had the same high molecular mass of about 85 kDa.

• Journal of Microbiology and Biotechnology
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• v.13 no.5
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• pp.651-659
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• 2003

A new method was proposed to control Harmful Algal Blooms (HABs) by a biosurfactant sophorolipid. The effect of sophorolipid on the growth, motility, precipitation, and recovery of algal cells was investigated for four common HAB species, Scripsiella trochoidea, Prorocentrum minimum, Cochlodinium polykrikoides, and Heterosigma akashiwo. The motility and growth of algal cells were inhibited significantly at the concentration of 20 and 5 mg/l sophorolipid, respectively, and no recovery was observed under the above concentrations. The concentration of 20 mg/l sophorolipid was considered to be an effective concentration for the mitigation of HABs. A sedimentation test suggested that the maximum precipitation occurred at the end of 1 h, and the algicidal effect of sophorolipid was observed by a microscope. Comparative study showed that sophorolipid had marked algicidal capability. Analysis on biodegradability, toxicity, and cost effectiveness further demonstrated the potential of sophorolipid in future HABs mitigation.

• Proceedings of the KSRS Conference
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• v.1
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• pp.364-367
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• 2006

Nonlinear internal waves (NLIWs) are usually generated by nonlinear process on linear internal waves (IW). Near HengChun Ridge that links Taiwan and Luzon Islands, we found that there are linear internal waves following NLIW and they travel westward at different speed, about 1.5 m/s for IW and 2.9 m/s for NLIW. This phenomenon was observed on site with ship radar and echo sounders, and later verified with thermistor chain. West of Luzon Strait, the separation of NLIW are 5 km or more, while linear internal waves are lines of wave crests at nearly equal distance that is only a few hundred meters apart. The current hypothesis is that most of the energy of internal tide forms a beam that propagates upward from the eastern shoulder of ocean ridge and later interacts with sea surface and thermocline. The interaction with thermocline generates linear internal wave that propagate along the pycnocline at about 1.5 m/s. The interaction with sea surface scatters internal wave energy downward, ensonifies the water column and generates large nonlinear waves that propagate westward at 2.9 m/s as mode 1 in a waveguide.

• Proceedings of the KSRS Conference
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• v.2
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• pp.934-937
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• 2006

In the northeastern South China Sea (SCS), fast westward moving (about 2.9 m/s) non-linear internal waves (NLIWs) are emanated nearly daily from the Luzon Strait. Their propagation speed is faster than NLIWs previously observed in the deep water of world oceans, their amplitude of 140 m or more is the largest free propagating NLIWs so far observed in the deep ocean. These NLIWs energized the top 1500 m of the water column, heaving it up and down in 20 min. Their associated energy density and energy flux are the largest observed to date. During 2005 and 2006 experiment, they were found west of the HengChun Ridge (HCR) that links Luzon and Taiwan Islands. This coincides with founding in satellite images, no NLIW front was found east of HCR. But, the turbulent environment east of HCR may prohibit surface signature of NLIWs that were emanated from sills between Batan Islands. The relative contribution of the two ridges on NLIW in Luzon Strait is still under study.

• Journal of the korean society of oceanography
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• v.34 no.4
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• pp.200-206
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• 1999

Seawater sampling is the primary task for the study of the marine environmental parameters that require shipboard or laboratory experiments for their analyses, and is also required for the calibration of some instruments for in situ measurement. A new automatic bottle (AUTTLE) is developed for seawater sampling at any desired time and water depth by self-triggering. Both any type of single or assembled mooring for 15 days and manual actuation by using a remote messenger as existing instantaneous single point water samplers are possible. Its sampling capacity and the resolution of time setting are 2 liters and 1 second, respectively. The result of a field experiment with an optical backscattering sensor (OBS) and a total of 14 AUTTLES for the in situ calibration of the OBS shows that the AUTTLE must improve our understanding on the behavior of the sand/mud mixtures in the environments with high waves and strong tides. The AUTTLE will serve as a valuable instrument in the various fields of oceanography, especially where synchronized seawater sampling at several sites is required and/or the information in storm period is important.

• Journal of the korean society of oceanography
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• v.37 no.1
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• pp.45-50
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• 2002

New production (NP) values in well-mixed waters of the Yellow Sea were estimated using two different methods and were compared with each other; one is from the quantum yield model of nitrate uptake and chlorophyll ${\alpha}$-specific light absorption coefficient, and the other is from a traditional $^{15}N$-labelled stable isotope uptake technique. The quantum yields of nitrate uptake were highly variable, ranging from 0.0001 to 0.04 mol $NO_3Ein^{-1}$, and the small values in this study might have resulted from either the partitioning into nitrate uptake of little portions of light energy absorbed by phytoplankton or that phytoplankton may predominantly utilize other N sources (E. G. ammonium and/or urea) than nitrate. The estimates (0.54-8.47 nM $h^{-1}$) of NP from the quantum yield model correlated well ($r^2$=0.67, p<0.1) with those (0.01-4.93 nM $h^{-1}$) obtained using the $^{15}NO_3$ uptake technique. To improve the ability of estimating NP values using this model in the Yellow Sea, more data need to be accumulated in the future over a variety of time and space scales.

• Journal of the korean society of oceanography
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• v.33 no.4
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• pp.137-145
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• 1998

In order to investigate the paleotidal structure and current pattern in the Yellow and East China seas (YECS) since the late Wisconsin, which is the last glacial maximum period, a two-dimensional version of the Princeton ocean model is used. We assume that subtracting the sea-level differences from the present one can produce paleobasins and that the paleotide did not differ greatly from the present one in the adjacent deep seas, the northwestern Pacific Ocean and the East Sea. We could successfully simulate the paleo-M$_2$ tides and tidal currents of 9000, 11000 and 13000 yr B.P. The result of the model shows considerable differences in the tidal pattern in each period. As the eustatic sea level rose, the amplitudes of the paleotides and the number of the amphidromic points generally increased, but the tidal currents in each paleobasin were strong and about the same order as the present day's. Based on these paleotide calculations, we suggest that there should have been active erosion in the paleobasin as in the present YECS, and the erosion should have played an important role on widening the paleobasin to the present shape, YECS.

• Journal of the korean society of oceanography
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• v.35 no.1
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• pp.46-55
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• 2000

In order to understand the role of heterotrophic protists in the coastal waters off Inchon, abiotic and biotic factors were measured from January 1992 to February 1993. Microbial carbon biomass (mean212.9$^{\pm}$119.1 $^{\mu}$gC/1) was composed of 4.2% bacteria, 0.3% cyanobacteria, 12.l% autotrophic nanoflagellates, 6.6% heterotrophic nanoflagellates, 5.8 heterotrophic ciliates and 71.0% diatom and Mesodinium spp. The carbon biomass of heterotrophic protists (heterotrophic nanoflagellates and ciliates) was highest in October 1992 (mean 37.8$^{\pm}$22.5 $^{\mu}$gC/1), and was low in August 1992 (mean 21.2$^{\pm}$10.8 $^{\mu}$gC/1) and in February 1993 (mean 19.5$^{\pm}$6.4 $^{\mu}$gC/1). However, the contribution of heterotrophic protists to total microbial carbon biomass was higher in January 1992 and February 1993 (about 21%) when the phytoplankton was dominated by nanoplankton than in August and October (about 9%) when large diatoms occurred in large numbers. This study suggests that in Kyeonggi Bay heterotrophic protists might play a more important role as prey for zooplankton and as consumers of bacteria & small phytoplankton in less productive seasons (especially winter) than in productive seasons (autumn), and that the classic trophic pathway from diatoms through copepods to fish might be dominant nearly every season.

• Journal of the korean society of oceanography
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• v.33 no.1-2
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• pp.18-27
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• 1998

Based on 53 quantitative samples collected in April (23 stations) and August (30 stations) of 1993, the species composition, distribution and abundance of macrobenthic invertebrates and bottom characteristics in Chonsu Bay were conducted. Bottom sediments consisted of mud at the close to the dyke, sandymud in the central bay, and coarse sand in the mouth of the bay. A total of 273 species (177 species in April and 200 species in August) were identified. Mean density per sampling station was 480 ind./m$^2$ in April and 1126 ind./m$^2$ in August, respectively. Number of species and densities decreased in the northern part of the bay. The macrobenthos showed a temporal difference in species composition, range of distribution, and community delimitation caused by larval settling. Although during the settling period in summer, large numbers of juveniles added in most of regions, unrelated to environmental conditions, but, successful recruitment may has been a rare event locally Theora fragilis (bivalve), Lumbrineris longifolia(polychaete), Neptys oligobranchia (polychaete) were numerically dominant, but their densities varied seasonally. Community structures of macrobenthos in Chonsu Bay were affected by several bottom environmental conditions, related to tidal current speed, regionally.

• Ocean Science Journal
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• v.41 no.2
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• pp.97-104
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• 2006

A useful radiance-converting method was developed to convert the Landsat-7 ETM+thermal-infrared (TIR) band's radiance ($L_{{\lambda},L7/ETM+}$) to that of Landsat-5 TM TIR ($L_{{\lambda},L5/TM+})$ as: $L_{{\lambda},L5/TM}=0.9699{\times}L_{{\lambda},L7/ETM+}+0.1074\;(R^2=1)$. In addition, based on the radiance-converting equation and the linear relation between digital number (DN) and at-satellite radiance, a DN-converting equation can be established to convert DN value of the TIR band between Landsat-5 and Landsat-7. Via this method, it is easy to integrate Landsat-5 and Landsat-7 TIR data to retrieve the sea surface temperature (SST) in coastal waters on the basis of local empirical algorithms in which the radiance or DN of Lansat-5 and 7 TIR band is usually the only input independent variable. The method was employed in a local empirical algorithm in Daya Bay, China, to detect the thermal pollution of cooling water discharge from the Daya Bay nuclear power station (DNPS). This work demonstrates that radiance conversion is an effective approach to integration of Landsat-5 and Landsat-7 data in the process of a SST retrieval which is based on local empirical algorithms.