• International Journal of Highway Engineering
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• v.16 no.1
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• pp.21-30
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• 2014

PURPOSES : Evaluation of input parameters determination procedure for dynamic analysis of aggregates in DEM. METHODS : In this research, the aggregate slump test and angularity test were performed as fundamental laboratory tests to determine input parameters of spherical particles in DEM. The heights spreads, weights of the simple tests were measured and used to calibrate rolling and static friction coefficients of particles. RESULTS : The DEM simulations with calibrated parameters showed good agreement with the laboratory test results for given dynamic condition. CONCLUSIONS : It is concluded that the employed calibration method can be applicable to determine rolling friction coefficient of DEM simulation for given dynamic conditions. However, further research is necessary to connect the result to the behavior of aggregate in packing and mixing process and to refine static friction coefficient.

• Advances in concrete construction
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• v.3 no.3
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• pp.161-185
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• 2015

FRP confining is a widely used method for seismic retrofitting of concrete columns. Several studies investigated the stress-strain behavior of FRP confined concrete prisms with square and rectangular sections both experimentally and analytically. In some studies, the monotonic stress-strain behavior of confined concrete was investigated and compressive strength models were developed. To study the reliability of these models, thorough statistical tests are required. This paper aims to investigate the reliability of the presented models using statistical tests including t-test, wilcoxon rank sum test, wilcoxon signed rank test and sign test with a level of significance of 5%. Wilk Shapiro test was also employed to evaluate the normality of the data distribution. The results were compared for different cross section and confinement types. To see the accuracy of the models when there were no significant differences between the results, the coefficient of confidence was used.

• Steel and Composite Structures
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• v.42 no.2
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• pp.265-275
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• 2022

A new type of precast steel reinforced concrete (PSRC) column was put forward in this paper. In order to study the static performance of PSRC column and hollow precast steel reinforced concrete (HPSRC) column subjected to combined compression and shear loading, a parametric test was carried out and effects of axial compression ratio, concrete strength and shear ratio on the mechanical behavior of composite PSRC column and HPSRC column were explored. In addition, the cracks development, load-span displacement relationship, strain distribution and shear bearing strength of column specimens were emphatically focused. Test results implied that shear failure of all specimens occurred during the test, and higher strength of cast-in-place concrete, smaller shear ratio and larger axial compression ratio could lead to greater shear resistance, but when the axial compression ratio was larger than 0.36, the shear capacity began to decrease gradually. Furthermore, truss-arch model for determining the shear strength of PSRC column and HPSRC column was proposed and the calculated results obtained from proposed method were verified to be valid.

• The Journal of Korean Society for School & Community Health Education
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• v.1 no.1
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• pp.1-9
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• 2000

The purpose of this study were to assess the effect on health promotion behavior of health instruction in elementary school and to provide a basis of school health education. Subjects of this study were random sampled 80 students for control group in elementary 6th grade students. the treatment group systematically studied five sphere instruction: individual hygiene, disease prevention, first-aid & safety, oral health, health & nutrition in two hours a week, from April 20, till July 10. Each group was pre-tested and post-tested by health behavior promotion questionnaire. The conclusions as follows; 1. Compare analysis of control group and treatment group in the pre-test according to health condition of children were no significant difference physical health condition, health anxiety, disease-absent(P>.05). 2. Health promotion behaviors in the post-test according to concern quotient significantly correlated with individual hygiene(r=.249, P<.05), disease prevention(r=.477, P<.01), oral health(r=.228, P<.05), health & nutrition(r=.323, P<.01) in the treatment group, on the contrary the disease prevention, first-aid & safety, oral health, health & nutrition(P>.05). 3. The difference of health promotion behavior within & between group were as follow; 1) The difference of individual health hygiene with in the treatment group was significant in pre-post test, the comparison of the two groups was significant difference in post-test(treatment group: $3.965{\pm}.568$, control group: $3.645{\pm}.573$). 2) The difference of disease prevention with in the treatment group was significant in pre-post test, the comparison of the two groups was significant difference in post-test(t group : $3.475{\pm}.619$, c group: $3.964{\pm}.600$). 3) The difference of first-aid & safety with in the treatment group was significant in pre-post test, the comparison of the two groups was significant difference in post-test(t group : $3.700{\pm}.466$, c group: $4.140{\pm}.545$). 4) The difference of oral health with in the treatment group was significant in pre-post test, the comparison of the two groups was significant difference in post-test(t group: $3.163{\pm}.665$, c group: $3.753{\pm}.544$). 5) The difference of health & nutrition with in the treatment group was significant in pre-post test, the comparison of the two groups was significant difference in post-test(t group : $3.255{\pm}.515$, c group: $3.698{\pm}.558$).

• Journal of Korean society of Dental Hygiene
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• v.15 no.2
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• pp.261-269
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• 2015

Objectives: The purpose of the study is to investigate the correlation and influencing factors of oral health awareness, oral health behaviors, self-esteem and OHIP-14. Methods: A self-reported questionnaire was filled out by 313 childcare teachers in Jeonnam from June 4 to 14, 2013. The questionnaire consisted of 3 questions of general characteristics, 4 questions of occupation, 1 question of oral health education experience, and 1 question of oral health education participation. The instrument for awareness and behavior of oral health were modified and consisted of 10 questions of awareness and 10 questions of behavior by Likert 5 scale. Cronbach's alpha was 0.718 in awareness and 0.812 in behavior. Instrument for self-esteem was modified from Rosenberg. Self-esteem questionnaire consisted fo 5 questions of positive answers and 5 questions of negative answers by Likert 5 scale. Cronbach's alpha in self esteem was 0.846 in the study. Oral Health Impact Profile-14(OHIP-14) was adapted from Slade by Likert 5 scale and consisted fo 14 questions. Cronbach's alpha was 0.934 in the study. Data were analyzed by chi square test, t-test, one way ANOVA, Scheffe multiple range test, Pearason's correlation test, and stepwise multiple regression test. Results: There were positive correlations between oral health awareness, oral health behavior(r=0.502), and self-esteem(r=0.332), but negative correlations with OHIP-14. Oral health behavior showed positive correlations with self-esteem(r=0.230). The factors on oral health awareness were high oral health behavior and self esteem, low OHIP-14, and active participation in education. Self-esteem was closely related to high with high oral health awareness. low OHIP-14, low job satisfaction. Conclusions: Childcare teachers play the very important roles in the development of oral health education program for children and continuous education.

• Korean Journal of Health Education and Promotion
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• v.22 no.2
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• pp.97-110
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• 2005

Objectives: Recent studies have shown that tailored messages for cancer screening to the beliefs and stage of cancer screening behavior of individual women increases the take-up probability. Many studies on cancer screening have used the Transtheoretical Model (TTM) to identify variables associated with cancer screening behavior. This study was carried out to identify the cognitive-behavioral factors associated with stomach cancer screening among women aged 40 years and over, and to develop and evaluate a tailored educational program for stomach cancer screening by stages of change. Methods: Building on the TTM constructs, we conducted a quasi-experimental study(N=283) to test the effectiveness of a tailored educational program for endoscopic stomach cancer screening. We carried out pre and post tests in the experimental group(N=162) and the control group(N=121), and the experimental group was subdivided into an on-line group(N=81) and an off-line group(N=81) by educational methodology using e-mail and the postal service. We used the chi-square test, trend test, and paired t-test to test the effectiveness of the program for stomach cancer using a tailored stage-matched messages. Results: To examine the effectiveness of the program for stomach cancer screening by the tailored stage-matched messages, the stage-matched materials were offered to the experimental group(N=162) four times for 4 weeks. The stage-matched materials consisted of the four types for stomach cancer. The tailored message was effective in changing the cognitive-behavioral factors, such as experience process, behavior process, con opinion for stomach cancer, self-efficacy, and the behavioral stages for stomach cancer screening. The stomach cancer screening adherence was higher for the stage-matched materials using postal mail than for those using e-mail. Conclusion: To improve the stomach cancer screening rate, the use of tailored messages for stomach cancer screening will be generated using an expert system. Therefore the implementation of tailored educational program will be supported a partnership between public and private health organizations and increasing awareness of the necessity of community-based interventions.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.4
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• pp.220-225
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• 2000

This paper develops a finite element model for studying occupant behavior of a mid-size truck equipped with a driver side airbag. The developed model simulates an occupant behavior using PAM-CRASH/PAM-SAFE in super computer SP2. The model is developed based on a sled test. A 50% hybrid dummy III is used for measuring head and chest accelerations and femur loads, and major injury coefficients such as HIC, CA and femur load. Inferior components such as foot rest, seat, kneebolster, crash pad, etc. are roughly modeled and defined by a rigid material model. And contact type II is used for detecting a contact with dummy. Contact type II definition uses force-deflection relationship of each body Such components as steering column which directly affect on the occupant injuy are modeled in detail and defined by an elastic-plastic material model. Airbag cushion is modeled using rivet elements. Airbag cover groove is modeled using rivet elements. Airbag tether is modeled as nonlinear bar elements. Airbag model has two vent holes to ventilating the exploded gas. Airbag is folded close to the real airbag folding procedure, and folded cautiously in order not to have initial penetration. A vehicle pulse acquired from 31mph frontal barrier test is used as input signal for the simulation. The simulation conditions are tuned to the sled test ones. The measured dummy accelerations and major injury coefficients, and filmed dummy behavior and airbag inflation process using high speed camera are compared to the simulation results to verify the developed finite element model.

• Steel and Composite Structures
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• v.36 no.3
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• pp.261-272
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• 2020

A novel precast concrete-encased steel composite beam, which can be abbreviated as PCES beam, is introduced in this paper. In order to investigate the shear behavior of this PCES beam, a test of eight full-scale PCES beam specimens was carried out, in which the specimens were subjected to positive bending moment or negative bending moment, respectively. The factors which affected the shear behavior, such as the shear span-to-depth aspect ratio and the existence of concrete flange, were taken into account. During the test, the load-deflection curves of the test specimens were recorded, while the crack propagation patterns together with the failure patterns were observed as well. From the test results, it could be concluded that the tested PCES beams could all exhibit ductile shear behavior, and the innovative shear connectors between the precast concrete and cast-in-place concrete, namely the precast concrete transverse diaphragms, were verified to be effective. Then, based on the shear deformation compatibility, a theoretical model for predicting the shear capacity of the proposed PCES beams was put forward and verified to be valid with the good agreement of the shear capacities calculated using the proposed method and those from the experiments. Finally, in order to facilitate the preliminary design in practical applications, a simplified calculation method for predicting the shear capacity of the proposed PCES beams was also put forward and validated using available test results.

• Journal of the Korea Concrete Institute
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• v.17 no.6 s.90
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• pp.963-974
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• 2005

This paper presented four shear test results from experimental tests of two large prestressed concrete beams cast with high strength concrete. In particular, this experiment investigated the effects of draped strands on shear behavior of these full-scaled beams. This study indicated that the use of draped strands increased the ultimate shear capacity as well as the web-shear cracking load. The test results also showed that draped strands reduced strand slip at ends of beams, which represented that these strands were effective to relieve the anchorage stresses. The test results were compared to predictions by two major codes; ACI 318-02 Building Code and AASHTO LRFD(2002). The shear design provisions in these codes provided conservative results on the shear strengths of all test specimens with reasonable margins of safety, and these provisions were particularly more conservative for test specimens having draped strands.

• Journal of the Korea Institute of Building Construction
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• v.6 no.2 s.20
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• pp.111-117
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• 2006

In case of carrying out vortical crossing water distribution system in expressways or general roads construction, VR(Vibrated and Rolled reinforced concrete) pipes are restricted because of their specification of reinforced spun concrete pipe or on-site made pipe. Therefore, in order to apply VR pipes to those constructions, through the structural behavior experiments of the pipes, VR pipes are compared and verified with reinforced spun concrete pipe and the results are obtained as the following. From the experiments and analyses of Pipe Stiffness(PS) of the pipes, cracking loading is approved to satisfy the KS regulations. Through a direct load test, the cracking loading strength and the maximum load test of VR pipe is larger compared with reinforced spun concrete pipe. Particularly, even if side weld is thin, there is no little change in the cracking strength of VR pipe. The results of the direct load test analysis show that the structural behavior of VR pipe is equivalent or higher compared with reinforced spun concrete pipe in performance and VR pipe could be used as the water distribution pipe for roads. In this study, through pipe stiffness, direct load test and load teat on earth, reinforced spun concrete pipe and VR pipe are compared. And as a result, the structural behavior of VR pipe is comprehensively excellent. From the structural behavior tests, VR pipe's section shows more thickness and has uniform characteristics so that VR pipe is considered more favorable than reinforced spun concrete pipe.