• Journal of the Korea Concrete Institute
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• v.15 no.5
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• pp.689-696
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• 2003

Recently, Appendix A of ACI 318∼02 Code introduced the Strut-and-Tie Model(STM) procedure in shear design of deep flexural members. The STM procedure is widely used in the design of concrete regions where the distribution of longitudinal strains is significantly nonlinear, such as deep beams, beams with large openings, corbels, and dapped-end beams. Experimental study included five high-strength reinforced concrete deep beams with different detailing schemes for the horizontal and vertical reinforcement. The specimens were designed as simply supported beams subjected to concentrated loads on the top face and supported on the bottom face. At failure, all specimen exhibited primary diagonal crack running from the support region to the point load. Specimens which had mechanical anchorages(terminators) gives better representation of the load-carrying mechanism than the specimen had standard 90-degree anchorage at failure in deep flexural members. Based on the test results, shear design procedures contained in the ACI 318-99 Code, Appendix A of the ACI 318-02 Code, CSA A23.3-94 Code and CIRIA Guide-2 were evaluated. The Shear design of ACI 318-99 Code, Appendix A of the ACI 318-02 Code and CIRIA Guide-2 shown to be conservative predictions from 10% to 36% in the shear strength of the single-span deep beam which was tested. ACI 318-99 Code was the lowest standard deviation.

• The Research Journal of the Costume Culture
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• v.15 no.3 s.68
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• pp.394-404
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• 2007

The purpose of the study was to analyze the difference in knitwear purchasing behaviors of female college students in the U.S., Korea, and China. It was developed questionnaire that included knitwear purchasing behavior that is fashion information sources, evaluation criteria of knitwear products, store attributes of knitwear, knitwear buying places, and purchasing experience of foreign-made knitwear. The final sample used in this study consisted of 119 female college students in U.S., 150 female college students in Korea, and 217 female college students in China. Aged from 18 to 33. ANOVA, factor analysis, Duncan's multiple range test, frequency, and percentage as analysis methods were used. The results of the study were as follows. The preference of knitwear among the respondents was shown highly. This result is due to a world-wide trend of casual clothing, and is to prove, that knitwear is that made with flexibility, drape, and stretch, is the item that is able to satisfy consumer's desires. Knitwear preference of knitwear the U.S. respondents was shown highly, and buying intention of them was also high, not only for sweaters and t-shirts but for pants, skirts, jackets, coats, and dresses as well. Knitwear information the U.S. respondents considered important, was not only purchasing experience but also shop display and magazine advertisements. By evaluating criteria of knitwear, the U.S. respondents considered good fit, design, color, and comfort important, and they didn't consider the country of origin important. By store attributes of knitwear, the U.S. respondents specially considered the display, variety, price level, and sale frequency of merchandise. The respondents of China was shown higher than them of Korea in the intention of all items. Knitwear information the China respondents considered important, was not only purchasing experience but also shop advertisements of Newspaper and magazine and fashion articles in Newspaper and magazine. By evaluating criteria of knitwear, the China respondents considered good fit, design, color, and comfort important, and they considered fiber content and the country of origin higher than the respondents of U.S. By Store attributes of knitwear, the China respondents specially considered product knowledge and friendliness of sales personnel, Layaway payment plan, Brand names, New Fashion, and Dressing Facilities higher than the respondents of U.S. or Korea.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.34 no.9
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• pp.1137-1143
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• 2010

This paper presents a fatigue design method for plug- and ring-type gas-welded joints, which takes into account the effects of welding residual stress. To develop this method, we simulated the gas-welding process by performing nonlinear finite element analysis (FEA) To validate the FEA results, numerically calculated residual stresses in the gas welds were then compared with experimental results obtained by the hole-drilling method. To evaluate the fatigue strength of plug- and ring-type gas-welded joints influenced by welding residual stresses, the use of stress amplitude $(\sigma_a)_R$, which includes the welding residual stress in gas welds, is proposed $(\sigma_a)_R$ on the basis of a modified Goodman equation that includes the residual stress effects. Using the stress amplitude $(\sigma_a)_R$ at the hot spot point of gas weld, the relations obtained as the fatigue test results for plug and ring type gas welded joints having various dimensions and shapes were systematically rearranged to obtain the $(\sigma_a)_R-N_f$ relationship. It was found that more systematic and accurate evaluation of the fatigue strength of plug- and ring-type gas-welded joints can be achieved by using $(\sigma_a)_R$.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.43 no.2
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• pp.77-82
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• 2017

Objectives: The aim of this study was to compare the mechanical resistance of four different osteosyntheses modeled in two different sagittal split ramus osteotomy (SSRO) designs and to determine the linear loading in a universal testing machine. Materials and Methods: An in vitro experiment was conducted with 40 polyurethane hemimandibles. The samples were divided into two groups based on osteotomy design; Group I, right angles between osteotomies and Group II, no right angles between osteotomies. In each group, the hemimandibles were distributed into four subgroups according to the osteosynthesis method, using one 4-hole 2.0 mm conventional or locking plate, with or without one bicortical screw with a length of 12.0 mm (hybrid technique). Each subgroup contained five samples and was subjected to a linear loading test in a universal testing machine. Results: The peak load and peak displacement were compared for statistical significance using PASW Statistics 18.0 (IBM Co., USA). In general, there was no difference between the peak load and peak displacement related to osteotomy design. However, when the subgroups were compared, the osteotomy without right angles offered higher mechanical resistance when one conventional or locking 2.0 mm plate was used. One locking plate with one bicortical screw showed higher mechanical resistance ($162.72{\pm}42.55N$), and these results were statistically significantly compared to one conventional plate with monocortical screws (P=0.016) and one locking plate with monocortical screws (P=0.012). The difference in peak displacement was not statistically significant based on osteotomy design or internal fixation system configuration. Conclusion: The placement of one bicortical screw in the distal region promoted better stabilization of SSRO. The osteotomy design did not influence the mechanical behavior of SSRO when the hybrid technique was applied.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.28 no.9
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• pp.343-349
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• 2016

Due to the recent increase in lighting energy consumption in buildings, there are a growing number of studies seeking solutions this problem. The effectiveness of light-shelves as natural lighting systems to solve this problem has been recognized, and various studies regarding such systems are being carried out currently. However, the lighting efficiency of light-shelves decreases if illumination intensity is low-such as at night time, and it also obstructs the views of building occupants. Therefore, the purpose of this study is to examine a movable drawer type light-shelf which allows for the width of the reflector to be adjusted and verify its performance through a simulated test-bed. The following conclusions were reached. 1) The purpose of this study is to solve the problem previously associated with the light-shelf system- of obstructed views-by responding to external environments and minimizing the width of the light-shelf at night time when the efficiency of the light-shelf declines. 2) The proper variables of the movable drawer type light-shelf which enables the width adjustment of the reflector were ascertained in this study according to four solar terms : a width of 0.6 m at an angle of $20^{\circ}$, a width of 0.4m with an angle of $20^{\circ}$, and a width of 0.1 m with an angle of $20^{\circ}$ were determined for the summer solstice, fall/spring equinoxes, and winter solstice respectively; revealing that width adjustment of the light-shelf is a significant factor. 3) The movable drawer type light-shelf which enables${\backslash}$width adjustment of the reflector suggested in this study can reduce the lighting energy consumption by 18.7% and 14.3% in comparison to previous light-shelves with a fixed width of 0.3 m and 0.6m, indicating that it is effective for saving energy.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.1
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• pp.89-96
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• 2022

In this paper, to evaluate the output quality of the cementitious composite mixture for printing with the ME method for construction 3D printer, visual inspection of the output appearance and the dimensional error rate, compressive strength and flexural strength of the output were measured. As a result of the test, the mixing design with excellent output appearance was P1-2, P1-4, P2-5, P2-6, and the mixing design with good output appearance was P0-1, P1-1, P1-3, P1-6, P1-7 and P2-4. Of these mixing designs, P0-1 and P2-6 had the lowest dimensional error rates As a result of evaluating the compressive strength and flexural strength of the various mixing designs, the Mixing design with excellent output designs showed good mechnical properties. However, mixing designs with excellent mechanical properties does not necessarily have excellent output quality. Therefore, in order to accurately evaluate the output quality, it is judged that visual inspection and dimensional error rate inspection should be performed first, and then the mechanical characteristics should be reviewed.

• Journal of the Korean Geosynthetics Society
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• v.22 no.3
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• pp.1-10
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• 2023

Recently, numerous structures have been constructed near the Nakdong river estuary, with pile foundations embedded in sand and gravel layers. In this study, the side resistance for six drilled shafts embedded in that region was evaluated based on the results of bi-directional and static axial compressive pile load tests. Subsequently, these results were compared with the side resistance calculated using domestic and foreign design codes such as FHWA (1999), KDS (2021), and AIJ (2004). Based on the test results, the evaluated side resistances ranged from 120 to 444kPa. However, the estimated values obtained from the design codes ranged from 69.3 to 170kPa, which were less than 50% of the evaluated values. It was observed that the empirical methods and correlations used in design codes provide a conservative estimation of the side resistance for drilled shafts embedded in sand and gravel layers. It implies that a suitable domestic approach should be developed to accurately estimate the side resistance of pile in sandy gravel and gravel layers near the Nakdong river estuary.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.19 no.6
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• pp.291-298
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• 2018

Purpose: The purpose of this study was to identify the effects of Problem-Based Learning on Academic Resilience, Learning Flow, and Academic Motivation in nursing students. Methods: Research design was a non-equivalent control group pretest-posttest design. The participants were 121 sophomore nursing students from two universities. They were divided into the Problem-Based Learning group (n=61) and Lecture-Based Learning group (n=60). The data were analyzed by Chi-square, paired t-test, and independent t-test. Results: In the PBL group, there was statistically significant improvement in Academic Resilience after intervention (pretest $3.88{\pm}.36$, posttest $4.00{\pm}.38$, p<.001). However, no statistically significant difference was found in the Lecture-Based Learning (LBL) group (pretest $3.86{\pm}.43$, posttest $3.93{\pm}.17$). In terms of Learning Flow, there was statistically significant improvement in the PBL group (pretest $3.31{\pm}.41$, posttest $3.51{\pm}.42$). However, no significant change was identified in the LBL group (pretest $3.45{\pm}.42$, posttest $3.48{\pm}.47$. Academic motivation was improved in the LBL group (pretest $3.32{\pm}.30$, posttest $3.46{\pm}.32$, p=.002) as well as in the PBL group (pretest $3.26{\pm}.23$, posttest $3.47{\pm}.21$, p<.001). Both results were statistically significant. Conclusion: These results suggest that Problem-Based Learning could be more effective for nursing students in improving their academic achievement. Further studies need to be investigated.

• International Journal of Highway Engineering
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• v.20 no.1
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• pp.107-115
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• 2018

PURPOSES : As the population of the mobility handicapped, who are classified as the disabled, the elderly, pregnant women, children, etc., has increased, the voices for guaranteeing their rights have been increasing as well. Thus, the design manuals for roads and sidewalks for the mobility handicapped were developed by the local government, such as the Ministry of Land, Transport, and Tourism, in Seoul City. However, according to the 2013 survey results of the Seoul Metropolitan City, the mobility handicapped still feel uncomfortable with the sidewalks, and particularly request for the improvement of the step and slope of the sidewalk curb. Therefore, in this study, we conducted an empirical experimental study to determine the slope of the sidewalk curb and height of the steps considering the mobility handicapped and analyzed whether there is a statistically significant difference. METHODS : The methodology of this study is an empirical experimental one. In the study, five non-disabled people, 10 wheelchair users, and 10 eye patch and stick users walked about 2-3 min on the sidewalk plates of the sloped type (0%, 5%, 6.3%, 8.3%) and stepped type (0 cm, 1 cm, 3 cm, 6 cm), and their human physiological responses, such as the skin temperature, volume of perspiration on forehead and chest, and heart rate, were measured and recorded. After combining the data, we conducted a nonparametric test, ANOVA, or t-test to determine whether there was a statistically significant difference according to each slope and step type. RESULTS : It was found that for the non-disabled, there was no significant difference in human physiological responses according to the slope and steps of the sidewalk. It can be said that the non-disabled do not feel much physiological discomfort while walking. In the case of the sloped sidewalk plate, the heart rate of the wheel chair users increased when the slope was 6.3%. In the case of the eye patch and stick users, the volume of perspiration on the chest increased at a slope of 5.0%. In general, it is judged that a sidewalk with a slope that is less than 5% does not cause a change in the physiological response. In the case of a stepped sidewalk plate, when 0 cm, 1 cm, and 3 cm were compared for wheelchair users, the amount of forehead perspiration increased from 1 cm. Meanwhile, in the case of the eye patch and stick users, when 0 cm and 6 cm were compared, the amount of perspiration on the forehead and chest as well as the heart rate all increased at 6 cm. Taken together, in the case of wheelchair users, a difference was shown when the height of the step of the sidewalk plate was 1 cm, suggesting that installing it at 0 cm does not cause any physiological discomfort. Moreover, in the case of the eye patch and stick users, when comparing only 0 cm and 6 cm, 0 cm was considered to be suitable, as there was a difference in physiological response at 6 cm. CONCLUSIONS : In this study, we set the human physiological responses such as chest skin temperature, amount of perspiration, and heart rate as evaluation items, and our study was considered to be a meaningful experiment that targeted wheelchair users as well as eye patch and stick users. The validity of the evaluation items was confirmed, as the results of human physiological responses were significant. As for the sidewalk design, according to the experiment result, it is considered that differential application should be implemented according to the type of mobility handicap, rather than uniformly applying a sidewalk step of 2 cm and sidewalk slope of 1/25, which are the current legal standards.

• Journal of the Korean Institute of Landscape Architecture
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• v.48 no.3
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• pp.34-44
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• 2020

In order to suggest performance analysis directions of ecological components based on a vegetation-based LID system model, this study seeks to analyze the statistical significance between monitoring results by using SWMM computer simulation and rainfall and run-off simulation devices and provide basic data required for a preliminary system design. Also, the study aims to comprehensively review a vegetation-based LID system's soil, a vegetation model, and analysis plans, which were less addressed in previous studies, and suggest a performance quantification direction that could act as a substitute device-type LID system. After monitoring artificial rainfall for 40 minutes, the test group zone and the control group zone recorded maximum rainfall intensity of 142.91mm/hr. (n=3, sd=0.34) and 142.24mm/hr. (n=3, sd=0.90), respectively. Compared to a hyetograph, low rainfall intensity was re-produced in 10-minute and 50-minute sections, and high rainfall intensity was confirmed in 20-minute, 30-minute, and 40-minute sections. As for rainwater run-off delay effects, run-off intensity in the test group zone was reduced by 79.8% as it recorded 0.46mm/min at the 50-minute point when the run-off intensity was highest in the control group zone. In the case of computer simulation, run-off intensity in the test group zone was reduced by 99.1% as it recorded 0.05mm/min at the 50-minute point when the run-off intensity was highest. The maximum rainfall run-off intensity in the test group zone (Dv=30.35, NSE=0.36) recorded 0.77mm/min and 1.06mm/min in artificial rainfall monitoring and SWMM computer simulation, respectively, at the 70-minute point in both cases. Likewise, the control group zone (Dv=17.27, NSE=0.78) recorded 2.26mm/min and 2.38mm/min, respectively, at the 50-minutes point. Through statistical assessing the significance between the rainfall & run-off simulating systems and the SWMM computer simulations, this study was able to suggest a preliminary design direction for the rainwater run-off reduction performance of the LID system applied with single vegetation. Also, by comprehensively examining the LID system's soil and vegetation models, and analysis methods, this study was able to compile parameter quantification plans for vegetation and soil sectors that can be aligned with a preliminary design. However, physical variables were caused by the use of a single vegetation-based LID system, and follow-up studies are required on algorithms for calibrating the statistical significance between monitoring and computer simulation results.