• 한국해양학회지
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• v.28 no.4
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• pp.259-271
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• 1993

The distributions of bottom sediments and the depositional processes on the continental shelves of Korean Seas are interpreted. Generally the continental shelf sediments can be classified into the sand-facies and mud-facies, showing the typical bimodal size distributions Most of the sandy and gravelly sediments on the outer shelf floor are interpreted as "relict" sediments that were deposited during the last glacial times when the sea level was lower than the present. On the other hand the muddy sediments on the inner shelf area are interpreted as "recent" sediments that are deposited under the present environment conditions. It is understood that most of the fine materials cannot escape the inner shelf area due to the strong tidal and coastal fronts, and are transported eastward from the West Sea along the southern coast of Korean Peninsula. The dark-colored muddy sediments in the Hupo Basin of the East Sea are, however, considered to be "relict" sediments. In the midshelf area fine materials are mixed with the relict coarse sediments, and some of the relict sediments are continuously reworked under the present environmental conditions forming the "palimpsest" sediments.

• Journal of The Korean Society of Inherited Metabolic disease
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• v.16 no.2
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• pp.102-108
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• 2016

Mitochondrial encephalopathy, lactic acidosis, and stroke-like episode (MELAS) syndrome is one of mitochondrial encephalopathy. As the early clinical manifestations can be variable, it is important to suspect the disease, especially in patients with multiple organ dysfunctions. A boy was diagnosed with epilepsy when he was 9 years old. Two years later, severe headache and blurred vision developed suddenly. On examination, left homonymous hemianopsia was detected with corresponding cerebral parenchymal lesions in right temporo-occipito-parietal areas. MELAS syndrome was confirmed by genetic test, which showed m.3243 A>G mitochondrial DNA mutation. Multivitamins including coenzyme Q10 were added to anticonvulsant. He experienced 4 more events of stroke-like episodes over 5 years, but he is able to perform normal daily activities. A 13-year-old boy was brought to the hospital due to suddenly developed respiratory arrest and asystole associated with pneumonia. Past medical history revealed that he had multiple medical problems such as epilepsy, failure-to-thrive, optic atrophy, and deafness. He has been on valproic acid as an anticonvulsant which was prescribed from local clinic. He recovered after the resuscitation, but his cognition and motor function were severely damaged. He became bed-ridden. He was diagnosed with MELAS syndrome by brain MRI, muscle biopsy, and clinical features. Genetic test did not reveal any mitochondrial gene mutation. Four years later, he expired due to suddenly developed severe metabolic acidosis combined with hyperglycemic hyperosmolar nonketotic coma. The clinical features of MELAS syndrome are variable. Early diagnosis before the presentation to the grave clinical course may be important for the better clinical outcome.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.20 no.2
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• pp.166-174
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• 1987

Distribution, bathymetry and textural parameters of the bottom sediment deposited between Geoje and Namhae Islands were studied to understand the depositional environment of the area. The study area is divided into three different provinces. Except for the Gwangyang Bay and Changseon Channel, mud dominates in the western part whereas sandy mud and muddy sand prevail in the southeastern part including the eastern area of the Yogji Island. The relict sediment is located in the eastern part of the area. Generally, the Holocene sediment, located in the northern part of the area, is considered to be transported and deposited by a pelagic suspension mode. Influence of strong tidal currents results in some depressions in the vicinity of Changseon Island and the eastern part of the Yogji Island, The Tsushima Warm Current is supposed to affect the southern part of the area. The two parallels sand ridges lying in the southeastern part of the area are covered with very thin Holocene mud. This seems to be caused by the winnowing effect of the current. The similarity between the two directions of the current and the ridges encourages this idea. The boundary between the Holocene and relict sediment, however, lies further south the ridges.

• 한국해양학회지
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• v.24 no.1
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• pp.39-51
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• 1989

A total of 139 surface sediment samples, collected from the continental shelf and slope off the southeastern coast of Korea, were analyzed in order to understand their grain-size, mineral composition and organic carbon content. Based on the grain-size characteristics, five surface sedimentary facies were distinguished: sand, clay, mud, sand-mud mixed, and sand-clay mixed facies. The sand facies appears to be composed mostly of relict sand. For mud, most of which seem to be of recent origin, two different sources were suggested, based principally on their areal distribution pattern and the local hydrographic conditions. Heavy mineral composition of the fine-sand size fraction allowed us to distinguish different sand populations from the study area. On the whole, the Hupo Bank sediments showed a high content of garnet, while the sediments from the northern part of the continental shelf were characterized by a relatively high content of metamorphic minerals (kyanite, sillimanite, andalusite, staurolite). Among clay minerals, the most abundant was illite, with chlorite, kaolinite and smectite following in decreasing order. Organic carbon contents in the sediments of the study area were generally high and showed an average value of 1.94%. The sediment grain-size exerted a strong influence on the organic carbon content. The highest organic carbon content, on the other hand, was found in the continental slope sediments.