• Korean Journal of Ichthyology
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• v.6 no.2
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• pp.93-98
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• 1994

The pipefish Syngnathus schelegeli was reared in the laboratory from May to June 1991 and observed the morphology of eggs and larvae squeezed from the parent fish(male). The diameter of inseminated eggs ranged from 0.72 to 1.01 mm (n=50), and yolk in yellow color were found in the eggs. The newly beared larvae were 10.9 mm in average standard length and had 59~60 myomeres. In 6 days after bearing, the post larvae attained 13.8 mm in average standard length and the low jaw was developed. The larvae of 14.1 mm in average standard length (8 days after bearing) had 40~42 fin rays in dorsal fin, 9 in caudal fin and 13~14 in pectoral fin. The juvenile of 14.7 mm in average standard length (10 days after bearing) had the well elongated snout along with the opercular and caudal fin similar to adult stage's.

• Korean Journal of Microbiology
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• v.45 no.4
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• pp.368-376
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• 2009

A red pigment-producing bacterial strain was isolated from sediment sample of the East China Sea. The isolate was identified by analysis based on 16S rDNA sequence and morphological, physiological properties, biochemical characteristics and fatty acid composition. Phylogenetic analysis based on 16S rDNA sequence showed that isolate represent a phyletic lineage within the genus Zooshikella, and this strain was most closely related to Zooshikella ganghwensis KCTC $12044^T$ (AY130994) (99.79%). The strain was Gram-negative, aerobic and required NaCl at 0.5~8.0% for growth. The predominant cellular fatty acids were saturated and monounsaturated straight-chain fatty acids. Consequently, this strain was identified as a member of the genus Zooshikella and designated as Zooshikella sp. JE-34. The pigment showed characteristics similar to prodigiosin, a well-known red pigment previously detected in Serratia marcescens. The antimicrobial activity of Zooshikella sp. JE-34 bacterial pigment was tested against 18 microorganisms, which were fish and human pathogens. The Zooshikella sp. JE-34 red pigment showed high antimicrobial activity against Streptococcus iniae, S. parauberis, S. mutans, Staphylococcus aureus, and Propionibacterium acnes.

• Korean Journal of Mineralogy and Petrology
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• v.36 no.4
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• pp.303-312
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• 2023

The determination of the oxidation states of metal elements in manganese nodules sheds light on the understanding of the formation mechanism of nodules, providing insights into the paleo-environmental conditions such as the redox potential of the aqueous system. This study aims to reveal the oxidation states and chemical bonding of manganese in the natural polymetallic nodules, utilizing conventional X-ray photoelectron spectroscopy (XPS). Specifically, shallow manganese nodules from the Siberian Arctic Sea, effectively recording mineralogical variations, were used in this study. Detailed analysis of XPS Mn 2p spectra showed changes in the manganese oxidation state from the center to the outer parts of the nodules. The central part of the nodules showed a higher Mn⁴⁺ content, approximately 67.9%, while the outermost part showed about 63% of Mn⁴⁺ due to an increase in the Mn³⁺+Mn²⁺. The decrease in the Mn oxidation state with the growth is consistent with the previously reported mineralogical variations from todorokite to birnessite with growth. Additionally, the O 1s spectra presented a predominance of Mn-O-H bonds in the outer layers compared to the center, suggesting hydration by water in the layered manganates of outer layers. The results of this study demonstrate that XPS can be directly applied to understand changes in paleo-environmental conditions such as the redox states during the growth of manganese nodules. Finally, future studies using high-resolution synchrotron-based XPS experiments could achieve details in oxidation states of manganese and trace metal elements.

• Korean Journal of Ichthyology
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• v.23 no.1
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• pp.21-29
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• 2011

Expression analysis of development-related genes was conducted using differential screening of 6-month-old [18M(-), 6M-18M] specific and 18-month-old [6M(-), 18M-6M] specific subtracted cDNA libraries constructed by subtractive hybridization using skeletal muscle of 6- and 18-month-old dark-banded rockfish Sebastes inermis. A total 202 cDNA clones displaying different expression levels in each stage were obtained; among them, 32 clones showing up-regulation were finally selected for further expression analysis. We sequenced the clones and analyzed individual sequences. Genes expressed specifically in 6-month-old skeletal muscle were identified as myosin, adenylate kinase, calsequestrin, dystrobrevin beta, and diphosphate kinase-Z1. Genes showing strong expression in 18-month-old rockfish were identified as desmin, TGFBR2 (transforming growth factor-beta receptor), muscle-type creatine kinase, and cathepsin D. Expression of these genes was checked further in 6-18-30-42 month-old dark-banded rock fish. Rapid reduction of expression was observed in dystrobrevin beta and diphosphate kinase. However, expression of creatine kinase (muscle type) and cathepsin D increased as dark-banded rockfish grew, and remained even after 18 months. The results reported here demonstrate that genes related to muscles contract are expressed at an early stage of development, and genes controlling energy in muscles are predominantly expressed at a late developmental stage.

• The Korean Journal of Malacology
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• v.24 no.3
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• pp.205-214
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• 2008

To evaluate the aquaculture potential of a subtrophic noble scallop, Chlamys nobilis in Korean waters, nursery growth of the species was studied on two remote Jeju coasts, Jigwido and Ongpori. The early growth performance of the first 60 days after settlement was expressed as: $SL=0.1664e^{0.0579x}$ ($r^2=0.924$), where x stands for days after settlement and SL for shell length. The early spats sized 1 mm in average shell length became $4.1{\pm}0.8\;mm$ after a month of nursery culture, thereafter grew to $13.0{\pm}1.9$, $23.1{\pm}3.1$, $30.3{\pm}4.3$, and $33.6{\pm}5.2\;mm$ for consecutive 4 months in Jigwido coastal area. Mean growth gains (mean daily gains in parenthesis) were $76.7{\pm}7.7$ ($165.6{\mu}m$), $73.3{\pm}7.3$ ($154.0{\mu}m$), $69.4{\pm}8.4$ ($140.0{\mu}m$), and $68.7{\pm}8.5\;mm$ ($137.4{\mu}m$), in depths of 5, 10, 15, and 20 m, respectively. The growth rate was significantly decreased as cultured in deeper place (p < 0.05). As culturing density was higher, growth performance of the scallop was decreased in both locations. Overall, in our preliminary study, the growth performance of scallop in Korean waters was not better than that in Japan, but it seems to be worth doing further study for successful introduction to Korean waters.

• Ocean and Polar Research
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• v.32 no.4
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• pp.439-448
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• 2010

General consensus on typical vertical profile of dissolved oxygen in the Ulleung Basin is that dissolved oxygen concentration beyond 300 m decreases with increasing depth. However, the results of our observations in 2005 and 2006 revealed three different dissolved oxygen distribution types in the deep layer of the Ulleung Basin. The first type showed oxygen concentration decreasing with increasing depth (Type-1), the second showed oxygen concentration decreasing very sharply near the bottom boundary layer but constant in the bottom adiabatic layer (Type-2), the final was of the oxygen minimum layer above the bottom boundary layer (Type-3). Type-2 was the most common pattern in the Ulleung Basin. Type-1 was most common close to the Japan Basin, including the Ulleung Interplane Gap, while Type-3 was found around Dok do. Oxygen Consumption Rate (OCR) at surface sediment estimated using the dissolved oxygen distribution at the bottom boundary layer was $0.2{\sim}5.8\;mmol{\cdot}m^{-2}d^{-1}$, which coincided with OCR from direct sediment incubation. This implies that organic matter decomposition at surface sediment may play an important role in dissolved oxygen distribution patterns at the bottom boundary layer of the Ulleung Basin.

• Economic and Environmental Geology
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• v.47 no.4
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• pp.395-404
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• 2014

We conducted the geophysical survey of possible hydrothermal vent sites at 2009, in the Lau Basin, the south western Pacific and analyzed the magnetic characteristics of TA19-1 and TA19-2 seamounts. TA19-1 is a cone-shaped seamount with a caldera summit. TA19-2 seamount is bigger and shows more complicated topography than TA19-1 seamount. TA19-2 has a large caldera, a summit in the west side of the caldera and several crests. Simple dipole anomalies with a high over the north and a low over the south occur in TA19-1 seamount. High magnetic anomalies are located in the northern flank and the summit of TA19-2 seamount and low anomalies around the summit and the caldera. The results of bathymetry and magnetic data suggest that TA19-2 seamount might have more complicated magmatic process than TA19-1. Low magnetization zones are located over the summit, the calderas and the caldera rims. The magnetization lows indicate that submarine hydrothermal vents, along faults and fracture zones, could have caused an alteration of magnetic minerals. The magnetization highs over the summit and the calderas might have been related with later magmatisms like volcanic sills, intrusions.

• Journal of the Korean earth science society
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• v.28 no.2
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• pp.187-201
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• 2007

The first magnetotelluric (MT) transect across the Korean Peninsula was obtained traversing from the East Sea shoreline to the Yellow Sea shoreline. The MT survey profile was designed perpendicular to the strike of the principal geologic structure of the Korean Peninsula $(N30^{\circ}E)$, so-called 'China direction'. MT data were achieved at 50 sites with spacings of $3{\sim}8km$ along the 240 km survey line. The impedance responses are divided into four subsets reflecting typical geological units: the Kyonggi Massif, the Okchon Belt, the western part of the Kyongsang Basin, and the eastern part of the Kyongsang Basin. In the western part of the Kyongsang Basin, the thickness of the sedimentary layer is estimated to be about 3 km to 8 km and its resistivity is a few hundred ohm-m. A highly conductive layer with a resistivity of 1 to 30 ohm-m was detected beneath the sedimentary layer. The MT data at the Okchon Belt show peculiar responses with phase exceeding $90^{\circ}$. This feature may be explained by an electrically anisotropic structure which is composed of a narrow anisotropic block and an anisotropic layer. The Kyonggi Massif and the eastern part of Kyongsang Basin play a role of window to the deep geoelectrical structure because of the very high resistivity of upper crust. The second layers with highest resistivities in 1-D conductivity models occupy the upper crust with thicknesses of 13 km in the Kyonggi Massif and 18 km in the eastern Kyongsang Basin, respectively.

• Geophysics and Geophysical Exploration
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• v.13 no.1
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• pp.31-39
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• 2010

The goal of automatic velocity analysis is to extract accurate velocity from voluminous seismic data with efficiency. In this study, we developed an efficient automatic velocity analysis algorithm by using bootstrapped differential semblance (BDS) and Monte Carlo inversion. To estimate more accurate results from automatic velocity analysis, the algorithm we have developed uses BDS, which provides a higher velocity resolution than conventional semblance, as a coherency estimator. In addition, our proposed automatic velocity analysis module is performed with a conditional initial velocity determination step that leads to enhanced efficiency in running time of the module. A new optional root mean square (RMS) velocity constraint, which prevents picking false peaks, is used. The developed automatic velocity analysis module was tested on a synthetic dataset and a marine field dataset from the East Sea, Korea. The stacked sections made using velocity results from our algorithm showed coherent events and improved the quality of the normal moveout-correction result. Moreover, since our algorithm finds interval velocity ($\nu_{int}$) first with interval velocity constraints and then calculates a RMS velocity function from the interval velocity, we can estimate geologically reasonable interval velocities. Boundaries of interval velocities also match well with reflection events in the common midpoint stacked sections.

• Journal of the Korean Society for Marine Environment & Energy
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• v.7 no.1
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• pp.35-41
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• 2004

The yeongok stream originates at the natural park, Mt. O-dae and flows to the East Sea of korea, normally maintaining I or II grade of water quality and its average water flux is 352,100 ㎥/d. However, the typhoon 'Rusa', which occured on 31 August 2002, changed its watercourse and configuration, and the ecosystem was deeply damaged. Moreover, the hydrological characteristics were once more transformed, and the ecosystem was secondarily damaged during repair-work of destroyed bridges and elevations. After the flood disaster, the species diversity diminished 17% for attached diatom and 44% for aquatic animals. However, the earth and sand, dug from river bed during intensive repair-work throughout the entire stream, made diversity drop to 32% for the diatom and the aquatic animals were wiped out. Especially, fishes were totally destroyed except for some species such as Moroco oxycephalus in the upper stream. The yeongok stream has little contamination source and short water residence time due to the short length and rapid slope, and consequently a temporary deterioration of water quality caused by repair-work may be rapidly recovered, but it needs a long time to restore the damaged ecosystem.