• Applied Biological Chemistry
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• v.50 no.3
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• pp.204-209
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• 2007

The objective of this research was to evaluate the inhibitory activities of phenolic compounds isolated from Crataegi Fructus on ${\alpha}-amylase$ and ${\alpha}-glucosidase$. The content of total phenolic compounds of water extract from Crataegi Fructus was 22.5 mg/g. The inhibitory activity of the water extract (200 ${\mu}g/ml$) from Crataegi Fructus on ${\alpha}-amylase$ and ${\alpha}-glucosidase$ was determined to be 100% and 82.6%, respectively. Isolation of inhibitory compounds was carried out on Sephadex LH-20 and MCI-gel CHP-20 column chromatography using a gradient elution procedure of increasing MeOH in $H_2O$. The chemical structure of the inhibitory compound against ${\alpha}-amylase$ and ${\alpha}-glucosidase$ was confirmed as chlorogenic acid by spectroscopic analysis of FAB-MS, NMR and IR spectrum.

• Journal of the Korea Concrete Institute
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• v.16 no.3 s.81
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• pp.407-414
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• 2004

The purpose of this study is to evaluate the ability to resist chloride ions penetration of the concrete structure under marine environment in south-east asia especially. In this study, high strength concrete(HSC) with various combination of ordinary portland cement(OPC), blast-furnace slag(SG) and silica fume(SF) are cured 23 and $35^{\circ}C$ considering the site weather, and are cured in water for 3, 7 or 56 days respectively. And to investigate the fundamental properties and the resistance of chloride penetration of various HSC, setting time, slump flow, compressive strength, void and ASTM C 1202 test were conducted. Test results show that the compressive strength of HSC is similar regardless of SG replacement ratio and total charge passed of chloride is the smallest at 40% replacement of SG. The compressive strength of G4FS HSC is, besides, outstandingly high at early age compare with other HSC, but the compressive strength of G4F HSC, which is vary according to curing temperature and condition, most high at the age after 7 days. Total passed charge of HSC get larger in the order G4FS

• Journal of Aquaculture
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• v.18 no.1
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• pp.37-44
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• 2005

This study was conducted to compare the physiological conditions of black porgy (Acanthopagrus schlegeli) when reared in freshwater (0 psu) and seawater (35 psu) during 90 days. In terms of stress response, there was no significant difference in cortisol levels of the fish reared either freshwater or seawater until 60 days. Although cortisol level of fish reared in freshwater(12.6$\pm$5.0 ng/ml) was significantly higher than in seawater (4.5$\pm$2.9 ng/ml) at the end of experiment, these values were stable levels as compared with that of non-stressed fish. No significant differences in plasma osmolalities were recognized between the fish reared in freshwater (346.7$\pm$4.6$\~$356.5$\pm$2.1 mOsm/kg) and seawater (350.0$\pm$2.0$\~$357.0$\pm$22.6 mOsm/kg). Normal structure of gill lamellae without histological damage or cell necrosis has been observed in the fish reared in freshwater. In connection with growth and survival rate, total length and body weight of fish reared in freshwater were slightly longer and higher than those of fish reared in seawater. Survival rate of black porgy reared in freshwater was slightly higher than that of fish reared in seawater, but there was no significant difference. The results suggest that black porgy is reared with normal growth rate in freshwater without stress.

• Korean Journal of Environmental Biology
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• v.23 no.2 s.58
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• pp.106-113
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• 2005

This study was conducted to examine the community structure of macrobenthos on Angel tidal flat in Jinhae, south coast of Korea. Monthly samples were conducted at eight sites from March 1998 to February 1999. A total of 110 species were sampled with a mean density of 322ind. $m^{-2}$ and biomass of 98.4 wwt g $m^{-2}$. Of these species, there were 44 species of polychaetes $(40.0\%)$, 41 species of crustaceans $(37.3\%)$ and 16 species of molluscs $(14.5\%)$. The major density dominant species were a gastropod Batilaria cumingi (52ind. $m^{-2}$) and five polychaetes Ceratonereis erythraeensis (38ind. $m^{-2}$), Cirriformia tentaculata (32ind. $m^{-2}$), Capitella capitata (23ind. $m^{-2}$), Sigambra tentaculata (23ind. $m^{-2}$), Glycera chirori (17ind. $m^{-2}$). Cluster and MDS analysis showed that the study sites could be divided into two tidal elevation groups. According to the spatial distribution of dominant species and SIMPER analysis, the two groups were characterized by Sigambra tentaculata - Chaetozone setosa in upper species group and Ceratonereis erythraeensis-Cirriformia tentaculata-Capitella capitata in lower species group.

• The Korean Journal of Petroleum Geology
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• v.9 no.1_2 s.10
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• pp.16-23
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• 2001

The study area in the East Sea is located on the northeastern margins of the Ulleung Basin near the Kita-Yamato Bank. The research area provides the important clue to the development of Miocene basins which are characterized by the normal faults and volcanic activities related to rifting in the continental crust. Kita-Yamato Bank is a small sediment-filled graben which was formed by failed rifting in the Early Miocene. The basins rapidly vary the bathymetry, depth of acoustic basement and thickness of sedimentary layer. The tension in the study area caused the extensional lithospheric deformation before/during the Early Miocene. In consequence, tectonic forces resulted in the depression or subsidence of basement from continental rifting in the Kita-Yamato Bank followed by the opening of the Ulleung Basin, and caused the onset of graben or half-graben structure bounded by large blocked syn-rift faults. Afterward no significant tectonic deformation exists, with the consequence that post-rift normal faults with small heave were formed and reactivated by the resultant forces such as tectonic subsidence, sediment loading and volcanic activity. The Cenozoic sediment layer has a maximum thickness of 1.0 s along the center of the graben or half-graben, which overlies the consolidated acoustic basement. Seismic units V and IV supposed to be syn-rift sedimentary rocks are deformed by both the volcanic activities and numerous basement-involved normal faults induced from extension. In the uppermost layer, slump scars resulted from the slope failure are recognized.

• Journal of the Korean Institute of Gas
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• v.24 no.5
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• pp.56-64
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• 2020

This study presents the hydrate induction time of PVCap according to subcooling temperature, salt concentration, and MEG concentration in order to analyze the inhibition effect of PVCap in various production environments of offshore gas fields. A high-pressure hydrate generator was made for the hydrate formation experiments. It was verified that the apparatus had sufficient reliability by comparing the results of hydrate equilibrium conditions and induction time from the apparatus with published reference data. As the subcooling temperature increased from 6.1℃ to 12.1℃, the induction time of PVCap concentration of 0.1~1 wt% decreased. When the salt concentration increased from 3 wt% to 7 wt%, the induction time was reduced by up to 78% under the condition of 0.5 wt% PVCap due to polymer structure degradation by salt effect. In the case of HHI (hybrid hydrate inhibitor) made by mixing MEG 10 wt% and PVCap, the change in induction time was not large compared to PVCap 1 wt% due to the under-inhibition effect. On the other hand, the hydrate inhibition efficiency of HHI with MEG 20wt% increased 1.7 times compared to PVCap.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.4
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• pp.228-237
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• 2015

Field observations were conducted to collect hydrodynamic and morphological data, which are needed to account for mechanisms of bathymetry changes caused by physical forcings, in Haeundae beach. In order to quantitatively describe characteristics of wave transformations and current patterns in space in winter and summer, in-situ sensors for measuring waves and current profiles were installed at three locations in the cross-shore direction and also three locations in the along-shore direction. As for the results of wave measurements, waves with main direction from the east dominate in winter while waves are incident from the S and the ESE in summer. Analysis of current data reveals that currents over the study domain are considerably influenced by a pattern of tidal motions, thereby, mainly oscillating in the direction of tidal currents, i.e., east-west directions, in both winter and summer. Currents tend to be influenced by local bathymetry in the shallow water region, with the direction changed along the depth contours and the magnitude reduced as they approach the shoreline. The results analysed from the hydrodynamic data through this study can be further combined with the morphological and bathymetry data, leading to the quantification of seasonal sediment transport rates and sand budget changes.

• Development and Reproduction
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• v.13 no.2
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• pp.115-122
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• 2009

Spermatogenesis and ultrastructural characteristics of sperm of brackish water diploid Corbicula japonica were investigated by electron microscope observations. Based on the cytological studies, the spermatozoon of this species (brackish water diploid) C japonica is approximately 55 ${\mu}m$ in length. The sperm head (about 12 ${\mu}m$ long) is elongated and tapers with a slight curve. Sperm nucleus is about 7.90 ${\mu}m$ long, and the acrosome is about 2.70 ${\mu}m$ long: The morphologies of the sperm nucleus type and the acrosome shape of this species are a long arrow-like type and long cone-like shape, respectively. The sperm head of this species (external fertilization, dioecious and oviparous species) is partially modified from that of the primitive type, as seen in triploid Corbicula species (internal fertilization, hermaphrodite and ovoviparous species), reported by some authors. However, this species produces uniflagellate spermatozoa, unlike freshwater triploid hermaphroditic clams being possessed of partially modified biflagellate spermatozoa. Diploid C japonica is similar to those of other bivalves being possessed of a short midpiece containing four mitochondria surrounding the centrioles. The axoneme of the sperm tail flagellum consists of nine pairs of microtubules at the periphery and a pair at the center. The axoneme of the sperm tail shows a 9+2 structure, and from uniflagellate sperm cross sectioned, in particular, wing-like axonernal lateral fins are observed, as seen in external fertilization fishes.

• The Korean Journal of Malacology
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• v.26 no.1
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• pp.51-62
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• 2010

The ultrastructures of germ cells and the accessory cells during spermatogenesis and mature sperm ultrastructure in male Gomphina veneriformis, which was collected on the coastal waters of Yangyang, East Sea of Korea, were investigated by transmission electron microscope observations. The morphology of the spermatozoon has a primitive type and is similar to those of other bivalves in that it contains a short midpiece with four mitochondria surrounding the centrioles. Accessory cells are observed to be connected to adjacent germ cells, they contain a large quantity of glycogen particles and lipid droplets in the cytoplasm. Therefore, it is assumed that they are involved in the supplying of the nutrients for germ cell development, while any phenomena associated with phagocytosis of undischarged, residual sperms by lysosomes in the cytoplasm of the accessory cells after spawning was not observed in this study. The morphologies of the sperm nucleus type and the acrosome shape of this species have a cylindrical and modified long cone shape, respectively. In particular, the axial filaments in the lumen of the acrosome, and subacrosomal granular materials are observed in the subacrosomal space between the anterior nuclear fossa and the beginning part of axial filaments in the acrosome. The spermatozoon is approximately $50-55{\mu}m$ in length including a long sperm nucleus (about $7.80{\mu}m$ in length), an acrosome (about $1.13{\mu}m$ in length) and tail flagellum ($40-45{\mu}m$). The axoneme of the sperm tail flagellum consists of nine pairs of microtubules at the periphery and a pair at the center. The axoneme of the sperm tail shows a 9+2 structure. Some charateristics of sperm morphology of this species in the family Veneridae are (1) acrosomal morphology, (2) the number of mitochondria in the midpiece of the sperm,. The axial filament appears in the acrosome as one of characteristics seen in several species of the family Veneridae in the subclass heterodonta, unlikely the subclass pteriomorphia containing axial rod instead of the axial filament. As some characteristics of the acrosome structures, the peripheral parts of two basal rings show electron opaque part (region), while the apex part of the acrosome shows electron lucent part (region). These charateristics belong to the family Veneridae in the subclass heterodonta, unlikely a characteristic of the subclass pteriomorphia showing all part of the acrosome being composed of electron opaque part (region). Therefore, it is easy to distinguish the families or the subclasses by the acrosome structures. The number of mitochondria in the midpiece of the sperm of this species are four, as one of common characteristics appeared in most species in the family Veneridae.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.140-146
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• 2020

The purpose of this study was to investigate the relationship among leisure supports, flow, and wellness of active senior leisure active participants. The subjects of the study were adults recruited from Seoul, Gyeonggi-do, and Jenla-do. For data processing, frequency, reliability, confirmatory factor, correlation, and structure equaling modeling analyses were conducted. The results were as follows. First, leisure supports of active seniors had an influence on leisure flow (p<.01). Second, leisure supports of active seniors had an influence on wellness (p<.01). Third, leisure flow of active seniors had an influence on wellness (p<.01). At this point in time as an aging society, active seniors are participating in leisure activities in a continuous pursuit of a healthy and happy old age by identifying the relationship between leisure support, leisure flow and wellness. This study suggests that our society should make an effort to participate in leisure and wellness activities.