• Transactions of the Korean Society of Mechanical Engineers
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• v.14 no.6
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• pp.1592-1602
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• 1990

Mixed mode surface crack in finite-width plate subjected to uniform tension and bending has been analyzed in 3-D problem by using boundary element method. The calculations were carried out for the surface crack angles(.a/pha.) of 0.deg., 15.deg., 30.deg., 45.deg., 60.deg., and 75.deg., and for the aspect ratio(a/c) of 0.2, 0.4, 0.6 and 1.0 to get stress intensity factors at the boundary points of the surface crack. For the aspect ratio of 1.0 and the surface crack angles, finite element method was used to check the results in this study. Comparison of the results from both methods showed good agreement.

• Journal of the Korean Wood Science and Technology
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• v.18 no.1
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• pp.39-51
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• 1990

This research was carried out to offer the basis data for development of optimum drying schedule for a domestic oak species (Quercus grosseserrata B1.) by investigating drying rate. stress, defect, and moisuture gradient with board thicknesses and drying schedules (code number T4-C2 and T3-B1). The results were obtained as follows: 1. Average drying rate and total drying time from 52.2% to 5.8% were 0.105%/hr and 486 hours for drying schedule T4-C2 and those from 62.1% to 8.3% were 0.070%/hr. and 811 hours for drying schedule T3-B1. 2. Drying rates for 28mm- and 31mm-thick boards showed similar tendency, but were significantly different from 25mm- thick board in drying schedule T4-C2 and those for 22mm-, 25mm- 28mm- and 31mm-thick boards showed similar tendency but were significantly different from 19mm- thick boards in drying schedule T3-B1. 3. The moisture gradients for drying schedule T4-C2 were steeper than those for drying schedule T3-B1 during drying period. and especially in early drying stage slow slope of moisture gradients of drying schedule T3-B1 was effective in preventing serious problem of surface checks. 4. Drying stresses were lower in drying schedule T3-B1 than in drying schedule T4-C2 during drying period. 5. Drying schedule T4-C2 was appropriate for 25mm-thick board but not for 28mm- and 31mm-thick board because of strong drying condition. Drying schedule T3-B1 was appropriate for 28mm- and 31 mm-thick board but not for 19mm-, 22mm-, and 25mm-thick board because of weak drying condition.

• Korean journal of food and cookery science
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• v.30 no.5
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• pp.650-662
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• 2014

This study was conducted to identify middle school students' caffeine intake from their favorite foods containing caffeine as well as several factors related to their intake. The objects of the investigation were 369 middle school students in the urban area of Changwon-si and 358 middle school students in the rural area of Haman-gun. The average height was 162.3cm, average weight was 52.3 kg and average BMI was 19.8. The food habit score was generally positive at an average of 3.37. The food habit scores of rural area students were higher than those of urban area students (p<.05). The average stress score was somewhat low at 2.82. The stress index for rural students was lower than that of urban students (p<.01). The recognition of caffeine in favorite foods was 8.12 out of a 12 point scale. The average nutritional knowledge score regarding caffeine was very low at 3.08 out of a 10 point scale. The main reason for selecting favorite foods was 'taste'. The percentage of students who don't check food labels was 49.1%. 'House' was the main location while 'good taste' was the biggest reason for eating caffeine-containing foods. The main side effect of caffeine intake was 'nausea'. The average daily caffeine intake for all subjects was 26.96 mg, with the urban students averaging 27.90 mg and the rural students averaging 25.99 mg. The correlations between several factors and caffeine intake were examined. Food habit showed a negative correlation with stress score and caffeine intake. Nutritional knowledge and recognition of caffeine had positive correlations with caffeine intake. Hence nutritional education about caffeine should be emphasized to improve students' healthy food habits.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.29 no.6
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• pp.539-545
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• 2016

UPS system in the liquefied natural gas(LNG) receiving terminal is one of the fundamental equipment that need to sustain operation during earthquake. In this study, modal identification test of UPS system was performed based on IEEE Std. 693-2005 and natural frequencies and modal damping, mode shapes had been identified. In addition, tri-axial time history test was performed to check the behavior and stress of the equipment during earthquake. Eigenvalue analysis was performed and analysis model was modified by reflecting the results of the test. Static analysis by dead weight and response spectrum analysis were performed to compare the combined stresses with the stress results of test. Dynamic characteristics and combined stresses under seismic load condition of the improved analysis model were similar to the test results and in this regard the compatibility was proved.

• International Journal of Highway Engineering
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• v.15 no.1
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• pp.23-36
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• 2013

PURPOSES: The problem under this circumstance is that the erosion not only drops strength of the steel dowel bar but also comes with volume expansion of the steel dowel bar which can reduce load transferring efficiency of the steel dowel bar. To avoid this erosion problem, alternative dowers bars are developed. METHODS: In this study, the bearing stresses between the FRP tube dowel bar and concrete slab are calculated and compared with its allowable bearing stress to check its structural stability in the concrete pavement. These comparisons are conducted with several cross-sections of FRP tube dowel bars. Comprehensive laboratory tests including the shear load-deflection test on a full-scale specimen and the full-scale accelerated joint concrete pavement test are conducted and the results were compared with those from the steel dowel bar. RESULTS: In all cross-sections of FRP tube dowel bars, computed bearing stresses between the FRP tube dowel bar and concrete slab are less than their allowable stress levels. The pultrusion FRP-tube dowel bar show better performance on direct shear tests on full-scale specimen and static compression tests at full-scale concrete pavement joints than prepreg and filament-winding FRP-tube dowel bar. CONCLUSIONS: The FRP tube dowel bars as alternative dowel bar are invulnerable to erosion that may be caused by moisture from masonry joint or bottom of the pavement system. Also, the pultrusion FRP-tube dowel bar performed very well on the laboratory evaluation.

• Membrane Journal
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• v.22 no.1
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• pp.54-61
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• 2012

To separate and recover of VOCs, supporting membranes using PEI were prepared by phase separation method and it was coated with PDMS to prepare PEI-PDMS hollow composite membrane. To investigate characteristic of prepared membrane, pure gas permeability was measured using oxygen and nitrogen, the stage cut and permeance property with feed concentration were evaluated using xylene, ethyl benzene, toluene and cyclohexane. Also, to check solvent resistance on VOCs, stress-strain property of membrane with immersion time in solvent were measured by DMA. The permeance value of $O_2$ and $N_2$ showed 63 GPU and 30 GPU respectively. Permeated VOCs concentration was decreased with increasing stage cut. But, conversely, recovery efficiency that was increased with increasing stage cut. As a result of DMA test, the stress and strain were 11.93 MPa and 13.52%, respectively.

• Anxiety and mood
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• v.6 no.1
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• pp.37-44
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• 2010

Objectives : This study investigated the influence of traumatic experience on the ego identity, self-esteem, and general psychopathology of adolescent North Korean refugees. Methods : The participants were 146 adolescents North Korean refugees who attended H High School for North Korean refugees. We divided the subjects into two groups according to the severity of their traumatic experience : the more-traumatic-experience group and the less-traumatic-experience group. Each group performed self-report assessments including an assessment to reveal demographic characteristics, the Traumatic Experiences Scale for North Korean Defectors, the Scale for Ego identity, the Scale for Self-esteem and the Symptom Check-90-Revision (SCL-90-R). Statistical analysis of t-test and multiple regression utilized SPSS 12.0 for Window for comparison between more-traumatic-experience group and less-traumatic-experience group. Results : The prevalence of posttraumatic stress disorder among adolescents North Korean refugees was 37%. The factor with the greatest influence on ego identity was length of time living in South Korea, while, for self-esteem the most influential factor was perception of health. The more-traumatic-experience group had lower self-esteem scores on some subscales of the Scale for Ego identity. They had higher scores on all SCL-90-R subscales than the less-traumatic-experience group. Conclusion : Adolescent North Korean refugees experienced high rates of posttraumatic stress disorder. The more traumatic-experience-group had lower self esteem and poorer ego identity and mental health than the less-traumatic-experience group.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3160-3165
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• 2011

The track and bridge interaction should be considered for the safety check of railway bridge design as the longitudinal forces transmitted to rail and bridge are changed by longitudinal stiffness of bridge system. The longitudinal stiffness of bridge structures is determined by the magnitude of the ballast resistance, the expansion length of superstructure, and longitudinal stiffness of substructure including pier and foundations. In this study, the main factors affect on the longitudinal rail forces are discussed and the computational parametric analysis of rail forces considering rail-bridge interactions. And the required range of stiffness of sub-structures and span length for the assurance of safety of CWR(continuous welded rail) track is suggested.

• Structural Engineering and Mechanics
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• v.6 no.7
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• pp.817-826
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• 1998

A finite element model based on the incremental endochronic theory for flexible pavement materials was developed in this study. Three grid systems with eight-node cubic isoparametric elements, and different loading steps were used to perform the calculations for a specimen of circular cylinder. The uniaxial stress experimental results on an asphalt mixture at $60^{\circ}C$ in SHRP conducted by University of California at Berkeley were used to check the ability of the derived numerical model. Then, the numerical results showed isotropic response and deviatoric response on the specimen in a three dimensional manner, which provided a better understanding for a deformed flexible material under the specified loading conditions.

• The Mathematical Education
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• v.23 no.2
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• pp.5-11
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• 1985

There arc numerous techniques available to appraise pupil achievement in elementary school mathematics. The teacher must utilize a variety of approaches to assess pupil growth in the mathematics curriculum. Each evaluation technique has its strengths as well as weaknesses. Thus, a specific evaluation technique may be utilized as a check on other approaches to appraisal. Pupil achievement must be assessed in terms of stated relevant understandings. skills, and attitudinal objectives. It is not adequate to appraise pupil growth in terms of understandings objectives only. Pupils must also be assessed in terms of skills objectives. The understandings acquired by learners must be utilized; thus, skills objectives need to be stressed adequately in ongoing units of study in elementary school mathematics. Adequate emphasis also needs to be placed upon pupils achieving attitudinal goals. Desireable attitudes on the part of learners aid in achieving understandings and skills objectives. A defensible program of evaluation would then stress that pupil achievement be adequately appraised in terms of understandings, skills, and attitudinal objectives.