• The Sea:JOURNAL OF THE KOREAN SOCIETY OF OCEANOGRAPHY
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• v.6 no.2
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• pp.81-92
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• 2001

According to analyses of high-resolution seismic profiles (air gun, sparker, and SBP) and a deep-drill core(YSDP 105) in the mid-eastern Yellow Sea, stratigraphic and geoacoustic models have been established and seismo-acoustic modeling has been fulfilled using ray tracing of finite element method. Stratigraphic model reflects seismo-, litho-, and chrono-stratigraphic sequences formed under a significant influence of Quaternary glacio-eustatic sea-level fluctuations. Each sequence consists of terrestrial to very-shallow-marine coarse-grained lowstand systems tract and tidal fine-grained transgressive to highstand systems tract. Based on mean grain-size data (121 samples) of the drill core, bulk density and P-wave velocity of depositional units have been inferred and extrapolated down to a depth of the recovery using the Hamilton's regression equations. As goo-acoustic parameters, the 121 pairs of bulk density and P-wave velocity have been averaged on each unit of the stratigraphic model. As a result of computer ray-tracing simulation of the subsurface strata, we have found that there are complex ray paths and many acoustic-shadow zones owing to the presence of irregular layer boundaries and low-velocity layers.

• Journal of dental hygiene science
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• v.6 no.3
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• pp.201-206
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• 2006

Purpose: The purpose of this study was to analyze level of dental health knowledge and behavior in elementary student, school health educators should encourage students to have continuous dental care habits for lifelong dental health with practical education. Methods: The subjects in this study were 490 students of four-year, fifth-year and sixth-year from elementary school in Daegu areas. The data was collected through a structured questionnaire from 26, June to 27, June 2006. Collected data were analyzed into frequency and Chi-square test using Spss 10.0 program. Result: Level of dental health knowledge were high as 57.8% in high groups, dental health behavior were high as twice a day in toothbrushing, over three times in visiting frequency of dental clinic for one years and once time of a day in intake frequency of cariogenic food. dental health knowledge by an academic years and sex were significant difference all of four-year, fifth-year and sixth-year. dental health behavior by an academic years and sex were significant difference in visiting frequency of dental clinic for one years and in intake frequency of cariogenic food by an academic years, male and female were significant difference in toothbrushing of a day. relationships of dental health knowledge and behavior were significant difference in intake frequency of cariogenic food.