• Journal of the Korean GEO-environmental Society
• /
• 제16권9호
• /
• pp.23-32
• /
• 2015

This study examined blast testing measurement data which had been obtained from 97 field sites in Korea to investigate the comprehensive characteristics of rock blasting-induced vibration focusing on the effect of excavation types (tunnel, bench) and rock types. The measurement data was from the testing sites mostly in Kangwon province and Kyungsang province and rock types were granite, gneiss, limestone, sand stone, and shale in the order of number of data. The study indicated that the blasting-induced vibration velocity was affected by the excavation types (tunnel, bench) and bench blasting induced higher velocity than tunnel blasting. In addition, the vibration velocity was also highly affected by the rock types and therefore, it can be concluded that rock types should be considered in the future to estimate a blasting-induced vibration velocity. Furthermore, the pre-existing criteria was compared with the results of this study and the comparison indicated that there was a discernable difference except for tunnel blasting results based on the square root scaling and therefore, further studies and interests, which include the effects of rock strength, joint characteristics, geological formation, excavation type, power type, measurement equipment and method, might be necessarily in relation to the estimation of blasting-induced vibration velocity in rock mass.

• Journal of dental hygiene science
• /
• 제13권4호
• /
• pp.393-402
• /
• 2013

The purpose of this study was to examine the relationship between vitamin D and periodontal diseases based on the raw data of the 5th National Health & Nutrition Examination Survey of 2010. The subjects in this study were 1,327 people, and those whose data on major variables were missing and who suffered from diabetes and/or osteoporosis were excluded. As for data analysis, R2.15.1 program and PASW Statistics 18.0 were utilized. The findings of the study were as follows: 1. As for all the respondents aged 50 and up, there was no significant relationship between vitamin D and periodontal diseases. 2. As for the post-menopausal women including the women who underwent bilateral ovariectomy, the vitamin D-deficit group 1 (<10) were 6.66-fold more likely to suffer from periodontal diseases than the vitamin D-sufficient group (${\geq}30$) (OR, 6.66; 95% CI, 1.004~44.19). The above-mentioned findings ascertained that vitamin D had a significant negative correlation to periodontal diseases among the post-menopausal women including the women who underwent bilateral ovariectomy. This finding should be taken into account in terms of the prevention and management of periodontal diseases.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 한국전기전자재료학회 2008년도 하계학술대회 논문집 Vol.9
• /
• pp.169-169
• /
• 2008

To keep pace with scaling trends of CMOS technologies, high-k metal oxides are to be introduced. Due to their high permittivity, high-k materials can achieve the required capacitance with stacks of higher physical thickness to reduce the leakage current through the scaled gate oxide, which make it become much more promising materials to instead of $SiO_2$. As further studying on high-k, an understanding of the relation between the etch characteristics of high-k dielectric materials and plasma properties is required for the low damaged removal process to match standard processing procedure. There are some reports on the dry etching of different high-k materials in ICP and ECR plasma with various plasma parameters, such as different gas combinations ($Cl_2$, $Cl_2/BCl_3$, $Cl_2$/Ar, $SF_6$/Ar, and $CH_4/H_2$/Ar etc). Understanding of the complex behavior of particles at surfaces requires detailed knowledge of both macroscopic and microscopic processes that take place; also certain processes depend critically on temperature and gas pressure. The choice of $BCl_3$ as the chemically active gas results from the fact that it is widely used for the etching o the materials covered by the native oxides due to the effective extraction of oxygen in the form of $BCl_xO_y$ compounds. In this study, the surface reactions and the etch rate of $Al_2O_3$ films in $BCl_3/Cl_2$/Ar plasma were investigated in an inductively coupled plasma(ICP) reactor in terms of the gas mixing ratio, RF power, DC bias and chamber pressure. The variations of relative volume densities for the particles were measured with optical emission spectroscopy (OES). The surface imagination was measured by AFM and SEM. The chemical states of film was investigated using X-ray photoelectron spectroscopy (XPS), which confirmed the existence of nonvolatile etch byproducts.

• Geophysics and Geophysical Exploration
• /
• 제10권4호
• /
• pp.241-251
• /
• 2007

The observed spectra from Odaesan earthquake were fitted to a point-source spectral model to evaluate the source spectrum and spatial features of the modelling error. The source spectrum was calculated by removing from the observed spectra the path and site dependent responses (Yun, 2007) that were previously revealed through an inversion process applied to a large accumulated spectral dataset. The stress drop parameter of one-corner Brune's ${\omega}^2$ source model fitted to the estimated source spectrum was well predicted by the scaling relation between magnitude and stress drop developed by Yun et al. (2006). In particular, the estimated spectrum was quite comparable to the two-corner source model that was empirically developed for recent moderate earthquakes occurring around the Korean Peninsula, which indicates that Odaesan earthquake is one of typical moderate earthquakes representative of Korean Peninsula. Other features of the observed spectra from Odaesan earthquake were also evaluated based on the commonly treated random error between the observed data and the estimated point-source spectral model. Radiation pattern of the error according to azimuth angle was found to be similar to the theoretical estimate. It was also observed that the spatial distribution of the errors was correlated with the geological map and the $Q_0$ map which are indicatives of seismic boundaries.

• Journal of Korean society of Dental Hygiene
• /
• 제12권2호
• /
• pp.317-326
• /
• 2012

Objectives : This study aims to examine satisfaction of dental treatment and revisit and intention of recommendation to dental patients and to supply as a basic resource for dental management improvement. Methods : 645 dental patients to dental hospitals in G City were subjects of this study. 27 dental hospitals were randomly chosen per 5 or 6 in 5 Districts. The intention of the survey was explained to 645 patients and it was agreed to have questionnaire survey. Questionnaire survey was carried out for 2 weeks in April 2011. Total 593 were used for the analysis except for insufficient answer sheets. The analysis was executed by using SPSS 18.0 and the results are as follows. Results : 1. The highest figures are as follows: female was 53.29% in sex, 20-29 age group was 44.52%, graduates of university were 38.62%, students were 28.50%, monthly family income with 300-399 million won was 31.70%. As to the treatment, dental caries were highest with 46.21% followed by scaling with 40.81%. As to the number of visit, 39.80% were over 5 times, and as to the opportunity to use, 29.34% answered it because it is close to home. 2. As to satisfaction, male was 4.15, over 60years old was 4.58, self-employed was 4.33, friendship with dentist as opportunity to use was 4.37. And as to revisit intention, over 60 years old was 4.60, over postgraduate in education level was 4.38, self-employed was 4.43, over 5 times visit was 4.32, and fame as opportunity to use was 4.39 which were the highest. As to the intention of recommendation to others, female was 4.24, over 60 years old was 4.65, self-employed was 4.36, friendship with dentist as opportunity was 4.43 which were the highest and showed significant differences (p<0.05). 3. As to patient satisfaction, there were strong relevance between revisit intention and intention of recommendation with 0.769 and 0.744 respectively. And, as to revisit intention, it had significant relation with revisit intention with 0.791. 4. The explanatory power of the regression analysis on the factors affecting revisit intention was 61.20%. The revisit intention was high when the satisfaction of dental hospital was high (${\beta}$=0.767, p<0.001), the number of visit (${\beta}$=0.026, p<0.01), reason for a visit (${\beta}$=0.070, p<0.01), education level (${\beta}$=-0.063, p<0.05) and occupation (${\beta}$=0.078, p<0.05). 5. The explanatory power of the regression analysis on the factors affecting intention of recommendation was 59.9%. The intention was taken patients satisfaction(${\beta}$=0.601, p<0.001), dental hygienist's kindness (${\beta}$=0.218, p<0.001), female (${\beta}$=0.079, p<0.05), reason for a visit(${\beta}$=-0.059, p<0.05), dissatisfaction treat(${\beta}$=0.084, p<0.05), dentist's kindness (${\beta}$=-0.080, p<0.05), age (${\beta}$=0.054, p<0.05). Conclusions : To improve revisit rate of patients, the refurbishing hospital facility, treatment and kindness of dental hygienists and satisfaction of treatment must be improved. And it also needs to accept complaint from female patients in a positive manner, and understand and correct complaints actively from the perspective of patients.

• Journal of Korea Entertainment Industry Association
• /
• 제14권1호
• /
• pp.149-158
• /
• 2020

The purpose of this study was to examine relation of oral health awareness, knowledge and behavior in department dental hygiene, health-related majors and health-unrelated majors in attempt to provide basic data of oral health promotion and oral health education. This study were 591 female H university students in Gwangju. The interests of oral health, the recognition of importance for oral health, and recognition of one's own oral health status were highest in dental hygiene students, followed by health-unrelated majors and health-related majors. The level of oral health knowledge by the major was highest in dental hygiene students(9.73), followed by health-related majors(9.14) and health-unrelated majors(9.05). In the oral health behavior by major, students who brushed more than three times a day, used the oral care products and received regular dental examinations within 1 year were the highest in the dental hygiene major, followed by health-related majors and health-unrelated majors. The experience of scaling within 1 year was the highest in the dental hygiene major, followed by health-related majors and health-unrelated majors. The higher the oral health knowledge, increased awareness of oral health concern and the importance of oral health. Also, the higher the degree of interest in oral health, the greater the recognition that oral health is important and the more the oral health condition is perceived as healthy, It was found that the number of brushing increased. In this results, the higher the oral health knowledge, the higher the oral health awareness and the oral health behavior. It is necessary to find ways to develop or utilize various oral health education for university students.

• Korean Journal of Ecology and Environment
• /
• 제55권1호
• /
• pp.35-48
• /
• 2022

Fish assemblage of total 325 of Korean peninsula estuaries were surveyed to analyze the characteristics of community structure and diversity by sea areas for three years from 2016 to 2018. The scale (stream width) of Korean estuaries were various (14~3,356 m), and 68.9% of all estuaries showed salinity of less than 2 psu. Total 149 species classified into 52 families of fish were identified, and the dominant and sub-dominant species were Tribolodon hakonensis (relative abundance, RA, 12.5%) and Mugil cephalus (RA, 9.5%), respectively. The estuary of the Korean Peninsula had different physical and chemical habitat environments depending on the sea area, and accordingly, fish community structure also showed statistically significant differences (PERMANOVA, Pseudo-F=26.69, P=0.001). In addition, the NMDS (nonmetric multidimensional scaling) results showed the patterns that indicating fish community difference by sea areas, even though low community similarity within sea area (SIMPER, 21.79~26.39%). The estuaries of east sea areas were distinguished from the others in the aspects of which, the higher importance of migratory fishes and endangered species, and that of brackish species were characterized at south sea estuaries. However, the estuaries of west sea showed higher importance of species that have a relation with freshwater (primary freshwater species, exotic species), which is the result that associating with the lower salinity of west sea estuaries because of the high ratio of closed estuaries(78.2%). The SIMPER analysis, scoring the contribution rates of species to community similarity, also showed results corresponding to the tendency of different fish community structures according to each sea area. So far, In Korea, most studies on fish communities in estuaries have been conducted in a single estuary unit, which made it difficult to understand the characteristics of estuaries at the national level, which are prerequisite for policy establishment. In present study, we are providing fish community structure characteristics of Korean estuaries in a national scale, including diversity index, habitat salinity ranges of major species, distribution of migratory species. We are expecting that our results could be utilized as baseline information for establishing management policies or further study of Korean estuaries.