• Restorative Dentistry and Endodontics
• /
• v.38 no.4
• /
• pp.234-240
• /
• 2013

Objectives: This study evaluated the effects of intraradicular moisture on the pushout bond strength of a fibre post luted with several self-adhesive resin cements. Materials and Methods: Endodontically treated root canals were treated with one of three luting cements: (1) RelyX U100, (2) Clearfil SA, and (3) G-Cem. Roots were then divided into four subgroups according to the moisture condition tested: (I) dry: excess water removed with paper points followed by dehydration with 95% ethanol, (II) normal moisture: canals blot-dried with paper points until appearing dry, (III) moist: canals dried by low vacuum using a Luer adapter, and (IV) wet: canals remained totally flooded. Two 1-mm-thick slices were obtained from each root sample and bond strength was measured using a push-out test setup. The data were analysed using a two-way analysis of variance and the Bonferroni post hoc test with p = 0.05. Results: Statistical analysis demonstrated that moisture levels had a significant effect on the bond strength of luting cements (p < 0.05), with the exception of G-Cem. RelyX U100 displayed the highest bond strength under moist conditions (III). Clearfil SA had the highest bond strength under normal moisture conditions (II). Statistical ranking of bond strength values was as follows: RelyX U100 > Clearfil SA > G-Cem. Conclusions: The degree of residual moisture significantly affected the adhesion of luting cements to radicular dentine.

• Korean Journal of Food Science and Technology
• /
• v.30 no.3
• /
• pp.717-720
• /
• 1998

Some physico-chemical components of Chinese water chestnut were analysed to provide fundamental data for water chestnut processing and products development. The contents of moisture, crude protein, crude lipid, crude ash, crude fiber and carbohydrate of Chinese water chestnut were 79.40%, 1.74%, 0.06%, 1.10%, 0.60% and 17.71% respectively. Free sugars identified in Chinese water chestnut juice were sucrose 8.58%, glucose 1.64% and fructose 1.58% as major component and maltose as trace component. The proportion of major free sugars to total soluble solid content of juice was about 66.0%. Potassium content in Chinese water chestnut was 408.57 mg% as major mineral, iron and manganese content were 0.21 mg% and 0.08 mg% as minor mineral. $Vitamin\;B_1$ and C content were $31.2\;{\mu}g/100\;g$ and trace respectively. Organoleptic properties of Chinese water chestnut were fresh fruit odor and sweet taste as main flavor. Though water chestnut was boiled for 20 min, crunchy texture of flesh was almost maintained.

• Composites Research
• /
• v.16 no.6
• /
• pp.23-32
• /
• 2003

Applications of advanced composite material in construction field are tending upwards and development of all composite material bridges is making progress rapidly in home and abroad due to their high strength to weight ratio. This paper formulated the dynamic responses of the laminated composite structures subjected to moving load and analyzed the various dynamic behaviors using the finite element method. The nondimensionalized natural frequencies of a simply supported square-laminated composite plate are considered for verifications. Mode superposition and Newmark direct integration method are applied for moving load analysis. For structural models, dynamic magnification factor calculated for various velocities of the moving load and displacements characteristics of laminated composite structures due to the moving load are investigated theoretically Numerical results are presented to study the effects of lamination scheme, stacking sequence, and fiber angle for laminated composite structures during moving load. The various results on moving load and lamination through numerical analysis will present an important basic data for development and grasp the behavior of all composite material bridges.

• Bulletin of the Korean Chemical Society
• /
• v.33 no.11
• /
• pp.3706-3710
• /
• 2012

A novel silicon-containing arylacetylene resin (MSAR) modified by dipropargyl ether of bisphenol A (DPBPA) and dipropargyl ether of perfluorobisphenol A (DPPFBPA) was prepared separately. The curing behaviors of modified resins, DPBPA/MSAR and DPPFBPA/MSAR, were characterized with differential scanning calorimeter (DSC). The kinetic parameters of modified resins were obtained by the Kissinger and Ozawa methods. The results of dynamic mechanical analysis (DMA) revealed that the glass transition temperature ($T_g$) of the cured DPBPA/MSAR reached $486^{\circ}C$. According to the thermogravimetric analysis (TGA), the decomposition temperature ($T_{d5}$) of the cured resins and char yield ($Y_c$, $800^{\circ}C$) decreased as the dipropargyl ether loadings increased, especially in air. With the same weight loading, thermal stability of DPBPA/MSAR was better than that of DPPFBPA/MSAR. The carbon fiber (T300) reinforced composites exhibited excellent flexural properties at room temperature with a high property retention at $300^{\circ}C$.

• International Journal of Concrete Structures and Materials
• /
• v.11 no.2
• /
• pp.327-341
• /
• 2017

Openings in slabs are usually required for many different applications such as aeriation ducts and air conditioning. Opening in concrete slabs due to cutouts significantly decrease the member stiffness. There are different techniques to strengthen slabs with opening cutouts. This study presents experimental and numerical investigations on the use of Carbon Fiber Reinforced Polymers (CFRP) as strengthening material to strengthen and restore the load carrying capacity of R.C. slabs after having cutout in the hogging moment region. The experimental program consisted of testing five (oneway spanning R.C. flat slabs) with overhang. All slabs were prismatic, rectangular in cross-section and nominally 2000 mm long, 1000 mm width, and 100 mm thickness with a clear span (distance between supports) of 1200 mm and the overhang length is 700 mm. All slabs were loaded up to 30 kN (45% of ultimate load for reference slab, before yielding of the longitudinal reinforcement), then the load was kept constant during cutting concrete and steel bars (producing cut out). After that operation, slabs were loaded till failure. An analytical study using finite element analysis (FEA) is performed using the commercial software ANSYS. The FEA has been validated and calibrated using the experimental results. The FE model was found to be in a good agreement with the experimental results. The investigated key parameters were slab aspect ratio for the opening ratios of [1:1, 2:1], CFRP layers and the laminates widths, positions for cutouts and the CFRP configurations around cutouts.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.19 no.1 s.71
• /
• pp.73-83
• /
• 2006

The failure mechanism of a hollow bridge deck which is made of fiber reinforced polymer (FRP) to improve its durability and life time significantly is investigated using both experiments and analyses. While the Load-displacement behavior of the deck in the longitudinal direction is almost linear just before the failure, the behavior in the transverse direction shows a strong nonlinearity even in its initial response with relatively small magnitude of loads. We found that the nonlinearity is due to the imperfection of the connection between the flange and the web; a plastic deformation can t라e place in the connection. The argument is demonstrated using a simple structural model in which a rigid plastic hinge is introduced to the connection. We also checked the contribution of the delamination mechanism to the failure. But the delamination is not the main mechanism which initiates and causes the failure of the bridge deck. In order to improved the structural behavior of the deck in the transverse direction, we suggested that the empty space of the bridge deck is filled with a foam and confirmed the improved behavior by a numerical analysis.

• Journal of the East Asian Society of Dietary Life
• /
• v.18 no.5
• /
• pp.822-828
• /
• 2008

Optimal Chinese-noodle product in the aspect of preference and quality that added functionality, the focus was put on developing the stable high value-added product in a farm household. Experimental results showed that the value for infrared water-content analysis of moisture was $85.74{\pm}0.12%$, crude protein was $1.31{\pm}0.01%$, the crude fat $3.91{\pm}0.08%$, the ash $1.83{\pm}0.01%$, carbohydrate $1.08{\pm}0.03%$, and crude fiber $6.12{\pm}0.10%$. For all experiments with Chinese noodles, the grape peels were frozen and dried, powdered, and filtered with a 150-mesh strainer. The grape-peel powder, was added to the composite flour in a proportion of 0%, 1%, 3%, 5%, and 7%. The color of the cooked noodle appeared brown, demonstrating that the L-value decreased as the amount of grape-peel powder increased. The value of a, which corresponds to the level of redness, increased and the cooked noodle appeared brown as the amount of grape-peel powder added increased. The yellowness of the cooked noodle tended to decrease as the value of b, which corresponds to the level of yellowness, gradually (p<0.05). In the texture analysis, hardness was highest in the 7% grape-peel powder group, while the 5% groups showed the highest springness values. The 1% groups showed the highest cohesivness while the 7% groups were the chewiest. The 7% groups had the lowest stickiness values (p<0.05). It terms of sensory quality, the overall surface color, texture and taste were perceived as superior for the 3% grape-peel powder-added groups and lowest for the 7% group (p<0.001). The 3% treatment showed the best overall quality.

• Journal of the Korean Dietetic Association
• /
• v.24 no.4
• /
• pp.344-360
• /
• 2018

This study examined the sociodemographic factors, health-related habits, chronic diseases, dietary habits, and nutrient intake according to the self-rated health status in a group aged over 65 years by analyzing the nationally representative Korean survey data. A total of 1,510 subjects were analyzed among the participants of the 2016 Korean National Health and Examination Survey (KNHANES). Statistical analyses for complex samples were performed using the SPSS software package (version 19.0) The study subjects were divided into two groups (healthy group vs. unhealthy group) based on their self-rated health status. The percentage of the healthy group was 66.5%. Gender, age, education level, household income, job (P<0.001, respectively), marital status, and basic living allowance (P<0.05, respectively) were significant sociodemographic variables of the self-rated health status. Alcohol consumption (P<0.01), aerobic physical activity, stress, quality of life, not feeling very well, depression and activity restriction (P<0.001, respectively) were also significant health-related variables of the self-rated health status. Blood glucose, anemia (P<0.05, respectively), and chewing problems (P<0.001) were significant chronic disease-related variables of the self-rated health status. Adequate intakes of protein, dietary fiber, phosphorus, thiamin, niacin, vitamin C (P<0.001, respectively), calcium, sodium, potassium (P<0.01, respectively), iron, vitamin A, and riboflavin (P<0.05, respectively) were also significant variables of the self-rated health status. In complex samples multiple logistic regression analysis, the self-rated health status was influenced significantly by the aerobic physical activity (P<0.01), stress level (P<0.05), depression (P<0.001), quality of life (P<0.001), not feeling very well (P<0.001), activity restriction (P<0.001), chewing problem (P<0.05), and adequate intake of iron (P<0.05). These results suggest that activity restriction, mental health, adequate iron intake, and physical activity may be associated with the self-rated health status in the elderly.

• Korean Journal of Community Nutrition
• /
• v.15 no.4
• /
• pp.485-497
• /
• 2010

The purpose of this study was to investigate effects of the developed nutrition education program focused on individual daily energy requirements and food exchange units using Food Exchange System for diabetes mellitus at a community health center. Developed the nutrition education program, four weeks' nutrition education including provided twice individual meal as diet therapy (2 hour/lesson/week, 4 week), was provided to 20 diabetic elderly (12 male, 8 female, 50-75 yrs): 1st lesson "Introduction: management of diabetes mellitus", 2nd lesson "6 Food groups and sources of 6 food groups", 3rd lesson "Individual daily energy requirements and food exchange units", and 4th lesson "Food choice for diabetes mellitus". For effects' analysis of the developed program, we assessed the changes in anthropometric characteristics; biochemical characteristics and nutrient intakes using 24 hr recall method. Effects of the developed nutrition education program were as follows: weight was significantly decreased, blood urea nitrogen (BUN) and glycosylated hemoglobin (HbA1c) were significantly decreased, and distribution of subjects in BUN and HbA1c was significantly changed. In protein : fat : carbohydrate (PFC) ratio, it was significantly changed from 15.98 : 16.30 : 66.69 to 17.51 : 18.94 : 64.10. In evaluation of nutrient intakes by Dietary Reference Intakes for Koreans (KDRI), protein, fiber, fat, vitamin E, niacin, folic acid, calcium and zinc were shown significantly positive changes in distribution of subjects according to intake level. The index of nutrition quality (INQ), nutrition adequacy ratio (NAR) and mean nutrition adequacy ratio (MAR) were significantly increased. In conclusion, the developed 4 weeks' nutrition education program focused on individual daily energy requirements and food exchange units using Food Exchange System for diabetes mellitus at community health center may improve the symptom of diabetes mellitus.

• Journal of the Computational Structural Engineering Institute of Korea
• /
• v.32 no.6
• /
• pp.425-434
• /
• 2019

It is important to ensure the seismic safety of pile-bent bridges constructed in areas with thick soft ground consisting of various soil layers against seismic motion in these layers. In this study, several synthetic seismic waves that are compatible with the seismic design spectrum for rock sites were generated, and the ground acceleration history of each soil layer was obtained based on ground analyses. Using these acceleration histories, each soil layer was modeled using equivalent linear springs, and multi-support excitation analyses were performed using the input motion obtained at each soil layer. Due to the nonlinear behavior of the soft soil layers, the intensity of the input ground motion was not amplified, which resulted in the elastic behavior of the bridge. In addition, inputting the acceleration history obtained from a particular layer simultaneously into all the ground springs reduced the response. Therefore, the seismic performance of this type of bridge might be overestimated if multi-excitation analysis is not performed.