• Journal of dental hygiene science
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• v.9 no.1
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• pp.75-81
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• 2009

The effect of glass frit on the sintering behavior and mechanical properties of 3 mol% $Y_2O_3$-doped zirconia($3Y-ZrO_2$) have been studied. Up to 30 wt% of glass frit was added to $3Y-ZrO_2$. Sintering was performed in a box furnace up to $1300^{\circ}C$ for specimens with glass frit and $1600^{\circ}C$ for specimens without glass frit in air for 1h. Relative density and mechanical properties were measured to investigate the effect of glass frit. The addition of glass frit enhanced both sintered density and mechanical properties of $3Y-ZrO_2$ which is suitable for dental applications. Maximum sintered density 93.3% of theoretical density was obtained with the specimens containing 30 wt% frit sintered at $1300^{\circ}C$, whereas the optimum amount of frit addition for mechanical properties was determined as 10 wt%. Maximum value of strength, fracture toughness, and Vickers microhardness for specimens with glass frit were 206 MPa, $3.4\;MPa\;m^{1/2}$, and 5.3 GPa, respectively.

• Geophysics and Geophysical Exploration
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• v.10 no.1
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• pp.77-88
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• 2007

Following a successful bathymetric mapping demonstration in a previous study, the potential of airborne EM for seafloor characterisation has been investigated. The sediment thickness inferred from 1D inversion of helicopter-borne time-domain electromagnetic (TEM) data has been compared with estimates based on marine seismic studies. Generally, the two estimates of sediment thickness, and hence depth to resistive bedrock, were in reasonable agreement when the seawater was ${\sim}20\;m$ deep and the sediment was less than ${\sim}40\;m$ thick. Inversion of noisy synthetic data showed that recovered models closely resemble the true models, even when the starting model is dissimilar to the true model, in keeping with the uniqueness theorem for EM soundings. The standard deviations associated with shallow seawater depths inferred from noisy synthetic data are about ${\pm}5\;%$ of depth, comparable with the errors of approximately ${\pm}1\;m$ arising during inversion of real data. The corresponding uncertainty in depth-to-bedrock estimates, based on synthetic data inversion, is of order of ${\pm}10\;%$. The mean inverted depths of both seawater and sediment inferred from noisy synthetic data are accurate to ${\sim}1\;m$, illustrating the improvement in accuracy resulting from stacking. It is concluded that a carefully calibrated airborne TEM system has potential for surveying sediment thickness and bedrock topography, and for characterising seafloor resistivity in shallow coastal waters.

• Journal of Korean Society of Steel Construction
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• v.20 no.2
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• pp.333-345
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• 2008

concrete deck bridges are increasingly aplied to twin- girder bridges and open-stel box girder bridges.One of the most dificult isues in the design of shear conect ors is the mater of achieving ful composite action. Many connectors in smal area require a significant section los of precast decks resulting in difficult reinforcement details. In this closer spacing than the required minimum spacing in the design codes was evaluated through static tests. Test results s howed that the ultimate strength decreased as the conector spacing was reduced. The strength enhancement was observed due to aditional reinforcement for precast slabs or for shear pockets. Thus, the design of group stud shear connection needs to anticipate failure modes and the conector failure should be induced. Based on the test results, an empirical equation consi dering stud spacing was proposed to evaluate the ultimate strength of group stud shear conection. Fatigue tests showed n o reduction in fatigue life of the group stud shear conection in the range of this research. Details of the precast decks wer e enhanced using the findings of the study.

• Journal of Korean Society of Steel Construction
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• v.23 no.3
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• pp.337-347
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• 2011

In this study, seismic resistance of concrete encased U-shaped steel beam-to-steel H-shaped column connections was evaluated. Three specimens of the beam-to-column connection were tested under cyclic loading. The composite beam was integrated with concrete slab using studs. Re-bars for negative moment were placed in the slab. The primary test parameter was the details of the connections, which are strengthening and weakening strategies for the beam end and the degree of composite action. The depth of the composite beams was 600mm including the slab thickness. The steel beam and the re-bars in the slab were weld-connected to the steel column. For the strengthening strategy, cover plates were weld-connected to the bottom and top flanges of the steel beam. For the weakening strategy, a void using styrofoam box was located inside the core concrete at the potential plastic hinge zone. The test results showed that the fully composite specimens exhibited good strength, deformation, and energy dissipation capacities. The deformation capacity of the beam exceeded 4% rotation angle, which is the requirement for the Special Moment Frame.

• Journal of Korean Society of Steel Construction
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• v.26 no.5
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• pp.407-418
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• 2014

As a continuing work of previously conducted standard tension tests, full-scale flexural tests were conducted in this study to assess the structural performance the CJP groove welded joints connecting thick HSA800 plates. Two welding electrodes were available at the time of this experimental research; one was GMAW-based electrode A and the other FCAW-based electrode B. Three full-scale box-type beam specimens with single bevel- and V-groove CJP welded joints were fabricated from 60mm and 25mm thick HSA800 plates according to the AWS-prequalified groove welded joint details. In designing the specimens, all possible limit states like local and lateral torsional buckling were carefully controlled in order to induce flexural plastic yielding or eventual joint fracture. All the CJP joints made by both welding electrodes showed satisfactory performance and were able to transfer the tensile flange forces higher than that corresponding to the measured tensile strength of HSA800 flange plates. However, it should be noted that, during fabrication, serious concerns about the welding efficiency and workability of the GMAW-based electrode were raised by a certified welder. The fracture occurred at the unbeveled (or vertical) interface between the weldment and the base metal when the GMAW-based electrode was used in the single-bevel joint, implying the possibility of insufficient melting. Thus, the FCAW-based electrode B is again recommended as the choice of welding electrode for HSA800 plates. The limited test data of this study implies that the V-groove CJP joint should be used in favor of the single bevel CJP joint, if possible.

• Journal of Korean Home Economics Education Association
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• v.11 no.2
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• pp.89-110
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• 1999

The purpose of this study was to investigate the perception and eating behaviors of middle school students in Kwangju area about food and nutrition section of Home Economics course. The subjects were 480 middle school students. The major results were as follows： On the perception f food and nutrition section, the 1st graders learned ‘how to settle the problems related to food and nutrition and food choices’. The 2nd graders learned ‘the knowledge and principle of food and nutrition for improving dietary life’. The 3rd graders learned ‘actual dietary life functions like arranging menu and preparing meals’. Consequently, there was a significant difference in each grade and all boy and girl students have the highest response to the item ‘they learn how to settle the nutrition problem and foods choices’. On the interests in food and nutrition section, lower graders and girl students have higher interest than hgiher graders and boy students. The area which was considered as most interesting in food and nutrition sections was ‘cooking’ in all students. The perception of the concern on dietary life after learning food and nutrition section was higher in the 1st graders. On the perception of the area where was a great change in their own dietary life after learning food and nutrition section, the 1st graders responded there was a great change in ‘balanced dietary life’, the 2nd graders in ‘eating habit and nutrition of adolescence’and the 3rd graders in ‘cooking’. Especially, girl students showed more changes. On the perception of degree which food and nutrition section gives a help to actual life, students over 50% responded that it was helpful to their actual life. This showed that the lower the grades, the more help it gave to those students. On the perception of mother’s job, the students with working mother considered that they learned ‘actual dietary life functions like functions like arranging menu and preparing meals’from the food and nutrition section. In addition, they had high interests in the area of ‘cooking’. It was recognized that as the family size was greater, the food and nutrition section gave more helps to actual life. On eating behaviors of breakfast, the higher the grade, the more frequent they don’t have breakfast, boy students have more frequencies of having breakfast than girl students and the primary reason of not having breakfast is poor appetite. On whether going without a meal affects study or not, most of the 1st, 2nd and 3rd graders whether they are boys and girls or not responded it affected their study. On eating behaviors of lunch, most of boy and girl students in the 1st, 2nd 3rd grade have lunch box. On eating behaviors of supper, eating time is usually between 7：00 and 8：00 p.m and eating hour is mostly 10 or 15 minutes. On eating behaviors between meals, frequency of eating between meals is mostly once or twice a day and girl students have more frequencies of eating between meals, and the cause was hunger commonly in boy and girl students and ‘killing time’in girl students. The focus in getting the foods is ‘taste’and favorite food is fruit regardless of the grade.

• Journal of the Korean Geotechnical Society
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• v.34 no.3
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• pp.67-75
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• 2018

In this study, we developed a micropile equipped with ground fixing wedge device which is able to ensure the bearing capacity early before grouting by expanding the tip and exerting the tip surface friction while compressing and expanding the tip of the micropile during loading. The purpose of this study is to verify the applicability of the developed micropile to the ground with various kinds of strength and to compare its characteristics with those of the simple tip expansion micropile. A new test system including a model soil box which can measure the tip resistance and the tip skin friction separately was devised. The loading test was carried out according to the changes of the ground strength and the tip cross section using the devised test systems. As a result of the test, it was found that the developed micropile increased the tip skin friction due to the wedge horizontal force as the soil strength increased and could be applied more effectively to the ground with the strength not lower than the strength of the weathered rock. In addition, it was found that additional bearing capacity could be obtained due to the tip cross section expansion and the wedge horizontal force exertion even in the ground with the strength below the weathered rock strength.

• Child Health Nursing Research
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• v.20 no.4
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• pp.322-331
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• 2014

Purpose: The purpose of this study was to identify health literacy levels of elementary school students. Methods: Participants were 331 fifth and sixth graders in nine elementary schools located in Gyeongsangnam-do. Instruments were 42 health-related words derived from fifth-grade textbook 'Health in Daily Life' for linguistic health literacy, modified Korean Health Literacy Assessment Tool (KHLAT) for numeracy section of functional health literacy, items from a snack box and newspaper article for reading comprehension section of functional health literacy. Data were collected from July 15 to August 15, 2013. Results: The mean score for linguistic health literacy was $24.02{\pm}7.16$ of 42 (57.2% were correct answers). The mean score for functional health literacy was $9.27{\pm}2.30$ of 12 (77.3% were correct answers). There were significant differences in health literacy by grade and academic performance. Conclusion: This study results show that both linguistic and functional health literacy among elementary school students were not high enough to use health-related information and make appropriate health-related decisions. Therefore, it is important to develop strategies aimed at increasing health literacy levels, especially focused on underperforming students. It is also necessary that studies be done on the factors affecting the health literacy of elementary-school students.

• The Journal of Korean society of community based occupational therapy
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• v.3 no.2
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• pp.13-23
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• 2013

Objective : The purpose of this study is to evaluate the effect of task-oriented mirror therapy involve visual illusion on upper extremity functions in stroke patients. Method : We divided into two groups that task-oriented mirror therapeutic exercise program include visual illusion and not include. In order to determine the change in upper extremity function, Box & Block Test and Line-bisection Test was evaluated each time period. Result : The result of this study that we found out that all participation's upper extremity function had been improved during the intervention and sustained during baseline regression. Applying mirror therapy program include visual illusion group more improved trend line during the intervention, visual illusion group, it had been shown there are higher difference between visual illusion group and non-visual illusion group in upper extremity functions. Conclusion : It is thoughtful that task-oriented mirror therapy could help for stroke. It might be more effectiveness to apply who have exercise program include visual illusion.

• Journal of the Korea Concrete Institute
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• v.26 no.3
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• pp.267-275
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• 2014

Recently, the construction of curved bridge has increased, thus researchers perform the analytic studies on PSC curved bridge. However, the grid analysis method that are mostly used in the construction industry is not adequate to acquire the precise behavior evaluation of curved PSC briges. Therefore, the precise finite element analysis considering the effective variables were performed to establish the basis for the design method of curved PSC bridge by using 3D elements and bar element. The evaluated variables in this analysis were the number of girders, loading point, section figure, change of prestressing force. The results show the load carrying capacity of the 3 girder type bridge is 200% of that of the 2 girder type, and that applying load on outer girder makes the load resistance capacity and the deflection deviation of 2 girders smaller. The structural capacity of the bridge is improved when the section size is increased, but the efficiency of it is not sufficient enough compare to that of the change of prestressing forces. The change of prestressing forces shows that the camber and the load carrying capacity are linearly increased as PS force is increased. Moreover, when the PS force applied on outer girder is increased than that of inner girder, the deviation of deflection the girders decreases, thereby the stability of the bridge is enhanced.