Bentonite is considered as buffer of engineered barrier for retardation of radionuclide migration. Bentonite has low permeability, high swelling and high sorption capacity for radioactive nuclides. Properties have been widely investigated under various geochemical conditions simulating deep geological environments. The chemical stability of bentonite is an important factor in evaluating the long-term stability of the bentonite buffer. However, the presence of impurities in bentonite clays can reduce the retention capacity for retardation of radionuclide migration value of bentonite. Therefore, the bentonite purification is necessary. In the present study, grade improvement of montmorillonite was conducted using ultrasonic and froth flotation methods. As a result of confirming the grade of montmorillonite according to the optimal ultrasonic intensity for ultrasonic irradiation is 1.0 kHz of bentonite in Gyeongju (KJ-II) increased from 60% to 78%. In case of froth flotation method using PSS (0.1 mM) as a reagent, the grade of montmorillonite increased up to 90%.

PURPOSES : The purpose of this study is to enhance the reliability of artificial intelligence for a noise-based pavement condition rating system (to a target performance of 95 %). METHODS : By comparing four types of pattern recognition artificial intelligence, this work acquires high-quality learning data and optimizes data learning through analysis of error characteristics. RESULTS : The system reliability improved up to 97 % (82 % in a prior study). In addition, 100 % was achieved for the E(F) condition grade, which has a direct impact on maintenance decision making. CONCLUSIONS : KNN-DTW (K-nearest neighbor dynamic time warping) is judged to be the most suitable type of artificial intelligence for a noise-based pavement condition rating system; a 4-grade system is the most suitable for classifying pavement condition.

PURPOSES: The purpose of this study is to evaluate and improve the potential risk of road cave-ins due to subsurface cavities based on the deflection ratio measured with light falling weight deflectometer (LFWD) tests. METHODS : A cavity database for Seoul was developed and sorted. LFWD tests based on the database were conducted on pavement sections with and without road cavities detected by ground-penetrating radar (GPR) tests; after excavating the area, the cavity sizes were measured. The deflection ratio was applied and analyzed by cavity management grade methods of Japan and Seoul. RESULTS : The results of comparative analysis show that the deflection method can detect road cavities in areas of the narrow road (or in narrow areas of the road). The average deflection ratio of the cavity sections to the robust sections were 2.48 for high-risk cavities, 1.85 for medium-risk level cavities, and 1.49 for low-risk cavities. Risk levels in Japan and Seoul were reclassified according to the deflection ratios. CONCLUSIONS : LFWD test results can be applied to verify and improve the subsurface cavity risk level by comparing maximum deflection and deflection ratio between cavity area and non-cavity area at the loading center. LFWD devices also have more advantages compared with larger NDT(Nondestructive test) because FWD and GPR encounter difficulties in traffic control and they could not get in a narrow roads.

This study investigated the quality change of strip loin from hanwoo with quality grade 2 produced by dry aging, and compared the quality of dry-aged strip loin with that of strip loin from hanwoo with quality grade 1+. Hanwoo strip loins with quality grade 1+ (SL1) and 2 (SL2) after a day of slaughter and dry-aged strip loin (DSL2) aged for 21 days at 2℃ with 85% humidity were obtained from local markets. The proximate composition, pH, cooking loss, lipid oxidation, instrumental color (CIE L*, a* and b* value) and sensory properties of the strip loins were measured. DSL2 contained low moisture and high protein contents compared with SL2, and low fat, high protein, and high ash contents compared with SL1 (p<0.05). The pH and cooking loss were higher and lower, respectively, in DSL2 compared to SL2 (p<0.05). SL1 had a higher pH than DSL2 (p<0.05). However, the cooking loss was not different between SL1 and DSL2. The TBARS value was the highest in DSL2 and the lowest in SL2 (p<0.05). DSL2 had higher L* and b* value compared with SL2 (p<0.05). There were no significant differences of L*, a* and b* values between DSL2 and SL1. Sensory properties such as the color, flavor, taste, texture, and acceptability of DSL2 were higher than those of SL2 (p<0.05). There was no significant different in all sensory properties between DSL2 and SL1. According to the results, dry aging can improve the nutritional and sensorial quality of strip loin with quality grade 2 to quality comparable to quality grade 1+.

This study investigated spelling errors in English stories written by 206 students in an elementary school implementing Korean/English immersion education. Errors were analyzed using crosstab and MANCOVA. Findings are as follows. Spelling errors occurred in 4 categories in order from the most frequent to the least: substitution, omission, addition, and transposition. The error occurrences differed depending on grade level changes: lower grades (Grades 1-3) vs. higher grades (Grades 4-6). The students in both grade levels made more errors in substitution and omission: these error types were significantly decreased as they progressed to the higher grade levels. Errors in addition and transposition showed much fewer occurrences for both grade levels, and these errors did not show a significant decrease because of their rarer occurrences. Overall, the students’ spelling ability increased remarkably as they progressed in grade levels in the immersion environment.

A study on the dry beneficiation of sericite occurring in the Daehyun Mine of the Republic of Korea region as performed by applying selective grinding and air classification techniques. Quartz and sericite occurred in the raw ore as major components. The results of liberation using a ball mill and an impact mill showed that the contents of R2O were increased while SiO2 was decreased in proportion to decreasing particle size. According to the XRD, XRF analysis and the EDS of SEM analysis, the ball mill gave a better grade product in R2O content than the impact mill when the particle size was the same. When the raw ore was ground by the impact mill with arotor speed 57.6 m/sec and then followed by 15,000rpm classification using an air classifier, the chemical composition of the over flowed product was 49.65wt% SiO2, 32.15wt% Al2O3, 0.13wt% Fe2O3, 10.37wt% K2O, and 0.14wt% Na2O. This result indicates that the R2O contents were increased by 49.5% compared to that of the raw ore. From these results described above, it is suggested that hard mineral such as Quartz little ground by selective grinding using impact mill whereas soft mineral such as sericite easily ground to small size. As a result of that hard minerals can be easily removed from the finely ground sericite by air classification and the R2O grade of thus obtained concentrate was improved to higher than 10wt% which can be used for ceramics raw materials.

In this study, we analyzed on-site monitoring data for 15 tributaries in Geumho watersheds for 3 years (2011-2013) in order to sort out priorities on water quality characteristics and improvement. As a result of estimating contribution to contamination of the tributary rivers, Dalseocheon showed the highest load densities, despite the smallest watershed area, with 22.7% BOD5, 30.7% CODMn, 31.3% TOC and 47.6% TP. After conducting PCA (principal component analysis) and FA (factor analysis) to analyze water quality characteristics of the tributary rivers, the first factor was classified as CODMn, TOC, EC, TP and BOD5, the second factor as pH, Chl-a and DO, the third factor as water temperature and TN, and the fourth factor as SS and surface flow. In addition, arithmetical sum of each factor’s scores based on grading criteria revealed that Dalseocheon and Namcheon were classified into Group A for their highest scores - 96 and 93, respectively -, and selected as rivers that require water environmental management measures the most. Also, water environmental contamination inspection showed that Palgeocheon had the most number of aquatic factors to be controlled: BOD5, CODMn, SS, TOC, T-P, Chl-a, etc.