• Journal of Korea Water Resources Association
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• v.39 no.1 s.162
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• pp.79-88
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• 2006

An accurate prediction of inflow water temperature is essentially required for real-time simulation and analysis of rainfall-induced turbidity 烈os in a reservoir. In this study, water temperature data were collected at every hour during the flood season of 2004 at the upstream of Daecheong Reservoir to justify its characteristics during rainfall event and model development. A significant drop of river water temperature by 5 to $10^{\circ}C$ was observed during rainfall events, and resulted in the development of density flow regimes in the reservoir by elevating the inflow density by 1.2 to 2.6 kg/$m^3$ Two types of statistical river water temperature models, a logistic model(DLG) and regression models(DMR-1, DMR-2, DMR-3) were developed using the field data. All models are shown to reasonably replicate the effect of rainfall events on the water temperature drop, but the regression models that include average daily air temperature, dew point temperature, and river flow as independent variables showed better predictive performance than DLG model that uses a logistic function to determine the air to water relation.

• The Journal of the Korea Contents Association
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• v.17 no.5
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• pp.591-601
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• 2017

The purpose of this research was to identify the effects of factors determining life satisfaction (LS) of local residents in chungbuk province. After reviewing the literature, this research selected and developed the 9 categories and specific indicators of LS. This research had obtained data through a face to face investigation using questionnaire, which surveyed 1,619 residents at 11 local governments in chungbuk province. This research analyzed the data using descriptive statistical methods and multiple linear regression method. This research found that 1) the level of overall LS had 4.433 points out of 7, the level of residential environment satisfaction had highest point (4.911), but the level of leisure culture satisfaction had lowest point (4.155), 2) in multiple regression analysis, The effect of income and consumption level on LS was highest. The degree of labor and life-social services was important factor to increase LS. The results of this study were expected to provide many implications for implementing policies to improve LS in the country and local governments.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.17 no.9
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• pp.472-482
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• 2016

The purpose of this study was to determine if a geriatric injury would have a statistically significant relationship with the spatial safety within a specific region. To achieve the objectives of this study, an independent sample t-test and One-way ANOVA were performed to verify difference in mean value of regional safety grade, depending on the injury intentionality, injury location, activities at the time of injury, and injury mechanism, in 6,572 geriatric injury patients by combining the National Hospital Discharge Patients Injury Survey data and regional safety index data. The results of statistical validation suggested that there was no difference in the mean value of regional safety grade by sub-group with respect to the injury intentionality. However, a statistically significant difference was observed in terms of the mean value of regional safety grade in each sub-group with regard to the injury location, activities at the time of injury, and injury mechanism in connection with some areas of the regional safety index. Based on the results of such analysis, we derived and presented 3 implications related to policies and practice for the prevention of geriatric injury and a reduction of its occurrence rate in light of spatial safety after a discussion of the results through a comparison with previous studies that examined individual areas.

• Restorative Dentistry and Endodontics
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• v.23 no.1
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• pp.197-212
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• 1998

The purpose of this study was to evaluate the effects of fluoride application on the aspect of shear bond strength of three aesthetic restorative materials to dentin. One light-cured composite resin(Palfique Esterite) and two light-cured glass ionomer cements(Fuji II LC and Compoglass)were used in this study. 120 permanent molars were used for this study. The teeth were extracted due to the origin of periodontal disease. The crowns of all teeth were removed, and the remaining roots were embedded in epoxy resin. The mesial or distal surfaces of roots were ground flat to expose dentin and polished on wet 320-, 400-, and 600 grit SIC papers for a total of 120 prepared flat root dentin surfaces. The prepared samples were divided into six groups. Group 1, 3, and 5 were control groups and group 2, 4, and 6 were experimental groups. Sixty samples for experimental groups were treated with 2% NaF solution for 5 minutes. Group 1 and 2 were bonded with Plafique Esterite, group 3 and 4 were bonded with Fuji II LC, and group 5 and 6 were bonded with Compoglass. After 24 hours water storage at $37{\pm}1^{\circ}C$, all samples were subjected to a shear to fracture with Instron universal testing machine(No.4467) at 1.0 mm/min displacement rate. Dentin surfaces treated with each conditioners before bonding and interfacial layers between dentin and aesthetic restorative materials were observed under Scanning Electron Microscope(Hitachi S-2300) at 20Kvp. The data were evaluated statistically at the 95% confidence level with ANOVA test. The result were as follows; 1. Among the control groups, group 1 showed strongest bond strength and group 3 showed weakest. 2. Among the experimental groups, group 2 showed strongest bond strength and group 6 showed weakest. 3. Statistical analysis of the data showed that pretreatment of dentin with 2% NaF solution significantly decreased the bond strength of three aesthetic restorative materials to dentin(P<0.05). 4. SEM findings of fluoride treated dentin surfaces (2, 4, 6 group) demonstrated dentin surfaces covered with fluoridated reaction products. 5. Except group 4 and 6, resin tags were formed in all groups.

• Korean Journal of Remote Sensing
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• v.21 no.4
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• pp.253-271
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• 2005

We have analyzed surface water temperature and seasonal stratification of lakes in the Han river system using time-series Landsat images and in situ measurement data. Using NASA equation, at-satellite temperature is derived from 29 Landsat-5 TM and Landsat-7 ETM+ images obtained from 1994 to 2004, and was compared with in situ surface temperature on river-type dam lakes such as Paro, Chuncheon, Euiam, Chongpyong, Paldang, and with 10m-depth temperature on lake-type dam lake Soyang. Although the in situ temperature at the time of satellite data acquisition was interpolated from monthly measurements, the number of images with standard deviation of temperature difference (at-satellite temperature - in situ interpolated temperature) less than $2^{\circ}C$ was 24 on which a novel statistical atmospheric correction could be applied. The correlation coefficient at Lake Soyang was 0.915 (0.950 after correction) and 0.951-0.980 (0.979-0.997 after correction) at other lakes. This high correlation implies that there exist a mixed layer in the shallow river-like dam lakes due to physical mixing from continuous influx and efflux, and the daily and hourly temperature change is not fluctuating. At Lake Soyang, an anomalous temperature difference was observed from April to July where at-satellite temperature is $3-5^{\circ}C$ higher than in situ interpolated temperature. Located in the uppermost part of the Han river system and its influx is governed only by natural precipitation, Lake Soyang develops stratification during this time with rising sun elevation and no physical mixture from influx in this relatively dry season of the year.

• Korean Journal of Comparative Education
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• v.27 no.1
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• pp.247-284
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• 2017

The purpose of this study is to analyze firm's motivation of participating and investing in apprenticeship in Germany and Korea, and to investigate institutional factors influencing firm's motivation. By comparing institutional factors of the two countries, it aims to drawing out policy implications for improving Korean apprenticeship. The main method for data collection was comprehensive literature review on international organizations, each countries' government and research institutes' policy materials, statistical data, research outputs and media resources related to each countries' apprenticeship. Considering whether firm's motivation for participating and investing in apprenticeship is production-oriented or investment-oriented, Germany is more inclined to investment motivation with firm's covering net cost during apprenticeship period. On the other hand, Korea is more inclined toward production orientation with firm's expectation of gaining net profit during the training period. Why is firm's training motivation different in these two countries? The author tried to find the reason from the difference of institutional factors of the countries by dividing institutional factors into 4 categories: context(tripartite relations, legal framework), input (flexibility of the system, government incentive), process(training contents, training duration, quality assurance), and output(completion/retention rate, apprentice's productivity). The key implication from the comparative analysis of institutional factors is that it is necessary to enforce companies to have "accountability" on the minimum critical elements, but also to ensure them to have "autonomy" on the rest of the elements.

• Journal of the Korean Society of Radiology
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• v.12 no.7
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• pp.801-806
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• 2018

Germanium crystals have a dead layer that causes efficiency deterioration because the layer is not useful for detection but strongly weakens the photons. Thus, when the data provided by the manufacturer is used in the detector simulation model, there is a slight difference between the calculated efficiency and the measured efficiency.The shape and dimensions of the high purity germanium (HPGe) detector were determined by CT scans to accurately characterize the shape for the Monte Carlo roll simulation. It is found that the adjustment of the dead layer is a good match with the relative deviation of ${\pm}3%$ between the measurement efficiency and the simulation efficiency at the energy range of 50 - 1500 keV. Simulation data were compared by varying the thickness of the dead layer. The new Monte Carlo simulations were compared with the experimental results to obtain new blank layer thicknesses. The difference in dead layer results for the 1.5 mm thick end cap simulation model in 1.4 and 1.6 mm thick End Cap simulation models was a systematic error due to the accuracy of the end cap dimensions. After considering all errors including statistical errors and systematic errors, the thickness of the detector was calculated as $1.02{\pm}0.14mm$. Therefore, it was confirmed that the increase in the thickness of the dead layer causes the effect to be effected on the efficiency reduction.

• Journal of the Korea Convergence Society
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• v.9 no.11
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• pp.299-306
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• 2018

Changes in demographic and economic conditions affect corporate strategy, labor market and social welfare. The purpose of this study is to examine the effects of changes in population and economic situation on library use and to examine the income effect of library use. In order to achieve the purpose of this study, we analyzed the 10 year fixed library of public library statistics and statistical census data from 2008 to 2017 using the panel fixed effect model using the data of regional gross production and unemployment rate. And the changes in the economic and demographic characteristics of the region are used to confirm the regularity of the relationship between the changes in the usage situation of the libraries belonging to a certain region and the changes in the economic and demographic conditions in the respective regions. As a result of the analysis, the changes in the economic environment did not significantly affect the number of visitors to the library and the number of library users, but it was an important factor in the number of borrowers. This study is significant in that it shows how the economic environment changes affect the library. The result of this study is expected to be a theoretical basis for establishing the service policy of public libraries.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.9
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• pp.341-350
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• 2019

This research study was conducted to investigate the effect of knowledge, attitude and nursing professionalism on the confidence of the performance of nursing students who had experience with clinical practice and also to provide basic data for the development of nursing students' curriculum. The subjects who participated in this study were 286 students in the 4th year of nursing at two colleges in the Daegu and Gyeongbuk regions. The research data was analyzed using the SPSS 22.0 program. Confidence in performance of patient safety was higher for the women than for men, and for the students of an older age and higher academic achievement. Confidence in performance of patient safety was positively related to knowledge (r=.25, p=.000), attitude (r=.39, p=.000), nursing professionalism (r=.33, p=.000) and all these had statistical significance. On the multiple regression analysis, the coefficient of determination ($R^2$) was .49 and the explanatory power of the model was 49.2% (F=24.04, p=.000). The most important factor affecting confidence in performance of patient safety was the experience of having undergone patient safety education. Based on these results, it is necessary to seek various educational methods to expand the concept of patient safety from the beginning of the undergraduate course work. Especially, we think that various education strategies such as simulation education methods or information videos are needed to develop scenarios related to patient safety.

• Korean Journal of Heritage: History & Science
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• v.36
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• pp.241-266
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• 2003

Glass pieces excavated from Mireuksa Temple dated $7^{th}$ century A.D. were characterized by chemical composition, specific gravity and melting point. Lead isotope ratios of lead glasses were also compared with those of lead ore to attribute which lead ore was delivered for making lead glass. It was known that some lead glasses found in Japan were similar with those of Mireuksa Temple as comparing the data of chemical composition and lead isotope ratios. Characteristics of lead glass from Mireuksa Temple Thirty five glass pieces of Mireuksa Temple were analyzed for five oxides and found that all was lead glass system(PbO-$SiO_2$) with the range of 70~79% for PbO and 20~28% for $SiO_2$. The concentrations of oxides such as $Al_2O_3$, $Fe_2O_3$ and CuO were below 0.4%, 0.3% and 0.9%, respectively. Principal component analysis(PCA) as a statistical method was carried out to classify glasses with the similarities of chemical concentrations. The result of PCA has shown that three groups of glasses were created according to the excavation positions and two major oxides(PbO and $SiO_2$) greatly contributed to the dispersion of glasses on principal component 1(PC1) axis and trace element oxides($Al_2O_3$ and $Fe_2O_3$) for PC2 axis. Most of lead glasses were greenish by the efficacy of iron and copper oxides and some showed yellowish-green. The gravity of lead glasses was about 4.4~5.4 and estimated melting point was near $670^{\circ}C$. Lead isotope ratios of glasses were analyzed and found quite close to a lead ore from the Bupyeong mine in Gyeonggi-do. Comparison with lead glasses found in Japan Lead glasses of Mireuksa Temple were compared with those of Japan on the basis of chemical and physical data. Chemical compositions of Japanese lead glasses dated $7^{th}{\sim}8^{th}$ century A.D. were nearly similar with those of Mireuksa Temple but lead isotope ratios of those were separated into two groups. Three distribution maps of lead ores of Korea, Japan and China with lead isotope ratios were applied for lead glasses found in Japan. The result have shown that the locations of lead glasses from Fukuoka Prefecture coincided with the region of northen part of Korea and similar with those of Mireuksa Temple and lead glasses from Nara Prefecture dated $8^{th}$ century A.D. were located in the region of Japanese lead ore. This research has demonstrated that lead glasses of Mireuksa Temple conveyed to Miyajidake site, Fukuoka Prefecture around $7^{th}$ century A.D. and glass melting pots and glass beads excavated from Nara Prefecture confirmed the first use of Japanese lead ore for production of lead glasses from the end of $7^{th}$ century A.D.