• International Journal of Highway Engineering
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• v.7 no.2 s.24
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• pp.97-107
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• 2005

Since the purpose of wheel tracking test is to find out relative difference of mixture's rut resistance, the wheel is an important part in the test for obtaining a consistent output. This study is performed to examine efficiency of different wheel material, rubber and steel in wheel tracking test. The rubber was inserted as a ring on the outer face of the steel wheel, and thickness of rubber ring was 15mm and 7.5mm and 0mm (steel wheel without rubber), making the total outer diameter 200mm. The objective of this study was to select reliable wheel material type in wheel tracking test at $60^{\circ}C$ based on variance in output (rut depth and dynamic stability) and correlation with SD (deformation strength). The result of regression analysis of rut depth with Sd showed that $R^2$ values of wheel rubber thickness of 15mm, 7.5mm and 0mm were 0.7, 0.8 and over 0.9, respectively. In a case of steel wheel (0mm), the highest $R^2$ value was 0.9569. Therefore, the wheel without rubber ring was the best in output consistency level and coefficient of determination $(R^2)$ with deformation strength. Therefore, the steel wheel without rubber ring is suggested as the best choice for wheel tracking test of asphalt concrete.

• Ocean and Polar Research
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• v.35 no.2
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• pp.157-170
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• 2013

We investigated the seasonal succession of phytoplankton assemblages in the eastern part of the South Sea of Korea in relation to surface water masses. The study areas are under the direct influence of the Tsushima Warm Current (TCW) throughout the whole year, with its strength known to be seasonally variable. The region is also influenced by coastal waters (CW) driven from the South Sea of Korea and East China Sea, particularly in summer, as indicated by low salinity in the surface water. Nutrient property of the TCW can reveals whether the origin of the TCW is the nutrient-rich Kuroshio Current or the oligotropic Taiwan Warm Current. Surface chlorophyll-a (Chl-a) concentrations displayed a large seasonal variation for all stations, with high values found in spring and autumn and low values in summer and winter. At station M (offshore) and P (intermediate location between M and R), Chl-a concentrations in October were higher than those in March, when spring bloom normally occurs. This may be related to deeper mixed layer depths in October. Diatoms dominated under conditions of high nutrient supply in which Chaetoceros spp. and Skeletonema costatum-like spp. were abundant. S. costatum-like spp. dominated at stations R (onshore station) and P in December when there was greater nutrient supply, especially of phosphate. Flagellates and dinoflagellates dominated at all three stations after diatoms blooms. Dominant species were Scrippsiella trochoid in April and Ceratium furca in October at station R, and Gyrodinium spp. and Gymnodinium spp. at station M during summer, when the effect of the oligotropic Taiwan Warm Current and the oligotropic coastal water from East China Sea were strong. Redundancy analysis showed clear seasonal successions in the phytoplankton community and environmental conditions, in which both principal components 1 and 2 accounted for 69.6% of total variance. Our results suggested that environmental conditions seemed to be determined by the origin of the TCW and the relative seasonal strength of the water masses of the TCW and CW, which may affect phytoplankton growth and compositions in the study area.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.5
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• pp.1115-1125
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• 2009

Purpose: The purpose of this study was to investigate the Safety-practice and Its Related Factors among Elementary students in rural area, to provide the basic data for prevention for safety accident occurrence in order to improve the QOL. Methods: The subjects of this study were 549 elementary students using self-report questionnaires. The collected data was analyzed using descriptive statistics, t-test, ANOVA, Scheffe's test, Pearson correlation coefficient and stepwise multiple regression with SPSS 12.0 Program. Results: The mean score for level of the safety awareness was 3.55(${\pm}.36$) and of the safety practice, 2.98(${\pm}.48$). The score of Safety-practice was statistically significant difference according to students' gender(p= .028) and students' grade(p= .004), the number of friends(p= .002), the level of school life adaptation(p= .000), recognized learning proficiency(p= .000), personality(p= .005), curiosity(p= .003), the level of demand for safety education(p= .000), the level of safety-education conducted by parents(p= .000), the level of safety-education conducted by teacher(p= .000). Stepwise multiple regression analysis for Safety-practice revealed that the most powerful predictor was level of Safety-awareness and self-esteem, the level of safety-education conducted by parents explained 28.8% of the variance. Conclusions: Therefore, it is necessary to develop safety practice promotion program in order to enhance the quality of life of elementary students. Future studies need to be pursued to find various variances.

• Korean Security Journal
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• no.59
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• pp.91-108
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• 2019

The purpose of this study is to investigate the relationship between the number of first aid training and safety performance. The researcher's questionnaire consisted of three variables: necessity of first aid education, application to security practice, and improvement of job satisfaction. In this study, Chronbach's Alpha coefficients were calculated to measure the internal validity for the reliability of the questionnaire. In order to verify the validity of the measured variables, exploratory factor analysis was carried out using the Berimax rotation method. The mean variance extracted AVE and the conceptual reliability CR value of the measurement result variables were both above the allowable reference value of 0.5 and it was judged to be a good test in terms of intensive validity. As a result of the hypothesis test, the standardization coefficient was 1.106 for 'necessity of first aid education ⇒ applied to security practice work', and 'applied to security work practice ⇒ improvement of job satisfaction' was 1.063 and the relationship of hypothesis 1 hypothesis 2 was significant (+), Respectively. Therefore, in order to increase the job satisfaction of security related workers, it is necessary to support first aid education and to receive first aid education.

• Physical Therapy Korea
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• v.19 no.1
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• pp.1-9
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• 2012

The purpose of this study was to investigate the kinematic and kinetic changes that may occur in the pelvic and spine regions during cross-legged sitting postures. Experiments were performed on sixteen healthy subjects. Data were collected while the subject sat in 4 different sitting postures for 5 seconds: uncrossed sitting with both feet on the floor (Posture A), sitting while placing his right knee on the left knee (Posture B), sitting by placing right ankle on left knee (Posture C), and sitting by placing right ankle over the left ankle (Posture D). The order of the sitting posture was random. The sagittal plane angles (pelvic tilt, lumbar A-P curve, thoracic A-P curve) and the frontal plane angles (pelvic obliquity, lumber lateral curves, thoracic lateral curves) were obtained using VICON system with 6 cameras and analyzed with Nexus software. The pressure on each buttock was measured using Tekscan. Repeated one-way analysis of variance (ANOVA) was used to compare the angle and pressure across the four postures. The Bonferroni's post hoc test was used to determine the differences between upright trunk sitting and cross-legged postures. In sagittal plane, cross-legged sitting postures showed significantly greater kyphotic curves in lumbar and thoracic spine when compared uncrossed sitting posture. Also, pelvic posterior tilting was greater in cross-legged postures. In frontal plane, only height of the right pelvic was significantly higher in Posture B than in Posture A. Finally, in Posture B, the pressure on the right buttock area was greater than Posture A and, in Posture C, the pressure on the left buttock area was greater than Posture A. However, all dependent variables in both planes did not demonstrate any significant difference among the three cross-legged postures (p>.05). The findings suggest that asymmetric changes in the pelvic and spine region secondary to the prolonged cross-legged sitting postures may cause lower back pain and deformities in the spine structures.

• Journal of Environmental Health Sciences
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• v.40 no.6
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• pp.492-501
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• 2014

Objectives: The purpose of this study was to assess the validity of self-reported cigarette smoking status and investigate factors associated with the accuracy self-reported and measured urinary cotinine in Korean adults. Methods: We used data from the $1^{st}$ Korean National Environmental Health Survey (2009-2011) among adults aged ${\geq}19$ years (N=6,246). The survey examined self-reported smoking status, and urinary cotinine was regarded as the biomarker of exposure to tobacco smoke. Urinary cotinine was analyzed using a gas chromatography-mass spectrometry (GC/MS) and data analysis was conducted using IBM SPSS version 20.0, which uses the sample weight and calculates variance estimates to adjust for the unequal probability of selection into the survey. Results: We calculated a cut-off point (53.3 ug/L) by using a ROC (Receiver Operating Characteristic) curve. The smoking prevalence was 24.6% based on self-reported data and 28.2% based on urinary cotinine concentrations. When we assessed the agreement between self-reported and urinary cotinine, we found an average agreement of 97.7% among self-reported smokers and 94.5% among self-reported non-smokers. Among self-reported smokers, factors affected the discrepancy were age, household economic status and average number of cigarettes smoked per day. On the other hand, gender, former smoking experience, and exposure to SHS (second hand smoke) were associated with discrepancies among self-reported non-smokers. Conclusion: These results suggest that self-reported data on smoking status provide a valid estimate of actual smoking status. In future research, we will conduct a continuous monitoring study for reliability verification of the data to reduce potential interpretation errors.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.9
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• pp.234-242
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• 2018

This descriptive study aims to examine the factors that influence nursing students' adaptation to clinical practice. Data was collected from 180 nursing students between April 26 and May 4, 2018. A self-reporting questionnaire was employed, which comprised of 17 questions regarding transition shock, 24 questions about social support, two questions regarding the levels of preparedness for clinical practice, and 14 questions about the degree of adaptation to clinical practice. Collected data was analyzed using t-test, one-way analysis of variance, and stepwise multiple regression, as well as by calculating the Pearson correlation coefficient. Subjects' degree of adaptation to clinical practice had a negative correlation with their transition shock. The degree of adaptation had a positive correlation with the levels of preparedness for clinical practice (r = 0.35) and the sub-variables of social support in the domains of friends (r = 0.24), parents (r = 0.32), and professors (r = 0.38). The smaller the transition shock (B = -0.409) and the greater the levels of preparedness (B = 0.766), professorial support (B = 0.228), and parental support (B = 0.163), the higher the degree of adaptation to clinical practice. Transition shock had the greatest influence on the degree of adaptation to clinical practice felt by subjects, followed by their level of preparedness for clinical practice and professorial support. Hence, to increase the degree of adaptation to clinical practice, not only should individual nursing students be better prepared to conduct clinical practice and professors provide greater support, but also there needs to be measures implemented to reduce transition shock.

• Science of Emotion and Sensibility
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• v.20 no.1
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• pp.49-56
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• 2017

The purpose of this study was to investigate the effects of virtual reality bowling on emotional changes using EEG (Electroencephalogram). Sixteen bowling players who have at least three years of experiences in bowling participated in this study. Their aged ranged from 26 to 35 years old with a mean age of 29.6 years. The frontal lobes (Fp2-Fp1, F4-F3, F8-F7) of each player were measured while subjects were performing five games of bowling. And after performing every frame, their emotion was measured immediately with Visual Analogue Scale. The data were analyzed by one-way analysis of variance to test differences in the alpha value of each region of the frontal lobes. The dependent variable is the alpha power of the cerebral asymmetry. The results showed that players who scored a strike showed higher VAS values than those who missed the spares or cleared the spares; those who cleared spares showed higher VAS values than those who missed spares In addition, with respect to frontal R-L asymmetry score, the alpha-wave of the left frontal lobe was activated when scoring a strike and clearing spares and the alpha-wave of the right frontal lobe was activated when missing spares. In conclusion, the results of this study demonstrated that success or achievement in competition gives rise to positive emotions and vice versa. This study neurophysiologically proved that performance outcomes during a competition directly influence players' emotion and brain waves.

• Geophysics and Geophysical Exploration
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• v.15 no.4
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• pp.177-189
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• 2012

Evaluation of three-dimensional ore body modeling has been performed by applying the geostatistical integration technique to multiple geophysical (electrical resistivity, MT) and geological (borehole data, physical properties of core) information. It was available to analyze the resistivity range in borehole and other area through multiple geophysical data. A correlation between resistivity and density from physical properties test of core was also analyzed. In the case study results, the resistivity value of ore body is decreased contrast to increase of the density, which seems to be related to a reason that the ore body (magnetite) includes heavy conductive component (Fe) in itself. Based on the lab test of physical properties in iron mine region, various geophysical, geological and borehole data were used to provide ore body modeling, that is electrical resistivity, MT, physical properties data, borehole data and grade data obtained from borehole data. Of the various geostatistical techniques for the integrated data analysis, in this study, the SGS (sequential Gaussian simulation) method was applied to describe the varying non-homogeneity depending on region through the realization that maintains the mean and variance. With the geostatistical simulation results of geophysical, geological and grade data, the location of residual ore body and ore body which is previously reported was confirmed. In addition, another highly probable region of iron ore bodies was estimated deeper depth in study area through integrated modeling.

• Restorative Dentistry and Endodontics
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• v.32 no.6
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• pp.542-549
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• 2007

The purpose of this study was to evaluate the difference in the surface roughness after polishing and to evaluate the difference in color stability after immersion in a dye solution among four types of composite resin materials. Four light-polymerized composite resins(Shade A2) with different sized filler content(a nanofilled, a hybrid, a microfilled, a flowble) were used. Average surface roughness (Ra) was measured with a surface roughness tester (Surftest Formtracer) before and after polishing with aluminum oxide abrasive discs(Super-Snap). Color of specimens before and after staining with 2% methylene blue solution were measured using spectrophotometer(CM-3700d) with SCI geometries. The results of Ra and ${\Delta}E$ were analyzed by one-way analysis of variance(ANOVA), a Scheffe multiple comparison test and Student t-test(p=0.05). After polishing, Ra values were decreased regardless of type of composite resins. In surface roughness after polishing and color stability after staining, nanofilled composite resin was not different with other composite resins except flowable resins.