• Journal of agricultural medicine and community health
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• v.26 no.2
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• pp.161-179
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• 2001

Recent patterns of infections with digenetic larval trematodes from fresh-water fish were studied in five locations of the river Taega during the period from October, 1998 to September, 2000, and compared with the data reported previously in the same river. The fish were collected using following techniques ; fishing, throwing a castnet, and using a bait of crushed oil cake in a transparent plastic bowl. Of 19 species of fish examined, eight species of encysted larvae, Clonorchis sinensis, Cyathocotyle orientalis, Centrocestus armatus, Clinostomum complanatum, Exorchis oviformis, Metagonimus species, Metacecaria hasegawai, and Metorchs orientalis, and two kinds of undetermined cyst A and C were found. The encysted larvae of Exorchis oviformis were found most frequently from 12 species of fresh-water fish, followed by Metacercaria hasegawai larvae from 9 species, the cyst of Clonorchis sinensis and Cyathocotyle orientalis from 7 species, Centrocestus armatus from 3 species, Clino- stomum complanatum from 2 species, and Metorchis orientalis from 1 species. The infection rates of fish with Clonorchis sinensis larvae were lower than those reported in 1993, whereas their intensity of infection was found lowered in 3 species, Pungtungia herz I, Saurogobio dabry i, and Squalidus jap onicus coreanus. The infection rates and intensity of 6 species of fish with Metagonimus sp ecies larvae were lower than the results in 1993, while the rates in several species of fish with Exorchis oviformis rather higher. The encysted larvae of Cyathocotyle orientalis, Metacercaria hasegawai, and Metorchis orientalis showed variations in infection rates of fish in 1993 and in the present study. However, It was impossible to compare the infection rates for the encysted larvae on the scales, fins and tail as they varied so considerably in both 1993 and 2000 surveys. This study indicate that the rate of infection with digenetic larval trematodes in fresh-water fish was still relatively high in the river Taega, and the metacercarial burden in the fish varies greatly by different fish in 1993.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.19 no.3
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• pp.234-240
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• 1986

Optical properties of sea vater were studied in Tokyo Bay, Japan, based on the data obtained from six oceanographic station in April, 1985. The observation of surface and underwater irradiances of sea water for eight kinds of wavelength (378, 422, 481, 513, 570, 621, 653, and 677 mm) of sun light was conducted using the underwater irradiameter (Isigawa ${\sharp}SR-8$). The mean attenuation coefficient of the sea water appeared to be 0.335($0.081{\sim}0.862$) and the attenuation coefficient of the sea water for each wavelength appeared as 0.268 for 378nm, 0.354 for 422nm, 0.274 for 481nm, 0.256 for 513nm, 0.284 for 570nm, 0.356 for 621nm, 0.425 for 653nm, and 0.464 for 677nm. The transparency was 5.0m ($2.5{\sim}6.5m$), water color was 10.2 ($8{\sim}14.0$) in the study area and the sun altitude was $53.62^{\circ}$ ($38.54^{\circ}{\sim}66.23^{\circ}$). The relationship between attenuation coefficient (K) and transparency (D) was K= 2.22/D ($1.30/D{\sim}3.54/D$). The rates of light penetration for eight kinds of wavelength (378, 422, 481, 513, 570, 621, 653, and 677 nm) were computed with reference to the surface light intensity each. The mean rates of light penetration in proportion to depths were $62.72\%$ ($42.23{\sim}78.43\%$) in 1 m layer, $11.91\%$ ($1.34{\sim}29.67\%$) in 5m layer, $2.64\%$ ($0.023{\sim}8.80\%$) in 10m layer, and $0.50\%$ ($0.02{\sim}3.99\%$) in 20 m layer. The rate of light penetration at the transparency layer with reference to the surface light intensity was shown as $12.51\%$ ($2.91{\sim}27.25\%$).

• Korean Journal of Heritage: History & Science
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• v.56 no.3
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• pp.22-44
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• 2023

The subsistence economics of the early Bronze Age has focused on explaining the intensity of agricultural practices without sufficiently taking into account the diversity of production methods that may arise from cultural types or environmental factors. The problem appears to stem from paying insufficient attention to the question whether we should understand the transition from the Neolithic Age to the Bronze Age as continuous or discrete. This has hitherto blocked an avenue to investigate the gradual changes in subsistence resource production methods. Taking as its premise that changes in the production methods of subsistence resources in the Bronze Age have been continuous and gradual, this paper seeks to restore the production patterns of subsistence resources according to the variety of factors that may have influenced the early Bronze Age production method. With diverse cultural patterns and ecological spaces of the early Bronze Age being confirmed, the work of restoring the production methods of subsistence resources in a specific period is difficult to achieve with one or two stand-alone analyses. A more appropriate method would involve separating a number of different aspects related to the production of subsistence resources, analyzing and interpreting each, and in the final stage, synthesizing the analyses. The specific research method employed in this paper checked for compositional differences in stone production tools, functionally categorized according to a variety of factors that have a close relationship with the production of subsistence resources: cultural-environmental factors and cultural patterns, geographical and topographical factors, soil productivity, and size of settlement. The results of the analysis are as follows: for the early Bronze Age production pattern of subsistence resources in the Seoul and Gyeonggi regions, while no substantive differences were observed with respect to cultural type, geographical and topographical location, the results show statistically significant differences in the composition of production tools according to settlement size and soil productivity. Also, with an increasing ratio of settlement size and total production soil, increases in hunting and armoring tools, woodworking tools, and harvesting tools were observed; on the other hand, when it came to the ratio of fishing tools, the opposite relationship was observed. While a correlation between settlement size or crop cultivation productivity and dependence on hunting or farming was expected, the results of the regression analysis show that settlement size and soil productivity ratios do not have mutually significant relationships. The results thus illustrate that patterns of production differ according to a variety of factors, and no single factor is decisive in the adoption of subsistence resource production methods by a specific settlement. Therefore, the paper emphasizes the need to investigate the production patterns of subsistence resources according to the variety of cultural and environmental factors that make up settlements in early Bronze Age society.