• Steel and Composite Structures
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• v.27 no.4
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• pp.417-426
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• 2018

This paper presents the seismic behaviors and restoring force model of ring beam joints of steel tube-reinforced concrete column structure under cyclic loading. First, the main failure mode, ultimate bearing capacity, stiffness degradation and energy dissipation capacity are studied. Then, the effects of concrete grade, steel grade, reinforcement ratio and radius-to-width ratios are discussed. Finally, the restoring force model is proposed. Results show that the ring beam joints of steel tube-reinforced concrete column structure performs good seismic performances. With concrete grade increasing, the ultimate bearing capacity and energy dissipation capacity increase, while the stiffness degradation rates increases slightly. When the radius-width ratio is 2, with reinforcement ratio increasing, the ultimate bearing capacity decreases. However, when the radius-to-width ratios are 3, with reinforcement ratio increasing, the ultimate bearing capacity increases. With radius-to-width ratios increasing, the ultimate bearing capacity decreases slightly and the stiffness degradation rate increases, but the energy dissipation capacity increases slightly.

• The Korean Journal of Emergency Medical Services
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• v.8 no.1
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• pp.87-104
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• 2004

This study selected the fifth and sixth graders of elementary school in Jeollanamdo who can express their opinions of safety consciousness and understand the items of questionnaire as the population. It selected 10 elementary schools under the supervision of Jeonnam Board of Education and sampled 700 students randomly from 2-3 classes in the 5th and the 6th grade. One preliminary survey was conducted to revise and complement the contents and forms of questionnaire with 70 students of a school from Apr. 1 to 6, 2004 and this study was conducted from Apr. 10 to 30, 2004. Data of this study were collected by explaining the purport of study to subjects after obtaining approval of principal and teacher of the school and distributing questionnaires. Total 700 questionnaires were distributed and 681 were collected (97%) and 602 were used for final analysis except 79 lacking responses. The results of this study are as follows. According to demographical characteristics of subjects, 'male' students were 302(50.%) and 'female' students were 300(49.8%) by sex and 'the 5th graders' were 285(47.3%) and 'the 6th graders' were 317(52.7%) in grade distribution. Residents at 'apartment house' were 406(67.4%) in residence type, 'going to school by foot' was 477 students(79.2%), 'high school graduates' were 297(49.3%) in fathers' education, 'high school graduates' were 366 (60.8%) in mothers' education, 'professional and office workers' were 231(38.4%) in fathers' job, 'full-time workers' were 283(47.0%) in mothers' job, and the number of siblings was one except myself in 343 students(57.0%). Respondents on the level of class showing 'good' were 340(56.5%) and those on the degree of adaptation to school life showing 'active' were 349(58.0%). On the characteristics related to safety education, 360(59.8%) responded it was 'very necessary', on the frequency of safety education at school for last one year, 339(56.3%) responded they had 'once or twice', on the frequency of safety education by parents, 279(46.3%) responded they 'often' had it, on the level of safety practice by parents, 347(57.6%) responded they practiced it 'frequently', on the source of knowledge of safety, 223(37.0%) responded they got it from 'parents, siblings and relatives', on the degree of recognizing the need of safety education textbooks, 295(38.5%) responded 'it was needed', on the recognition of necessity of teacher for safety education, 271(45.0%) answered it was very necessary', and on the recognition of qualification of teacher for safety education, 370(61.5%) answered it was 'paramedic'. The mean score of safety consciousness of subjects was 2.72 (SD. 21) of full score 3, having high score over mean score. According to each area, the area showing the highest safety consciousness was safety of fire(2.83), followed by home safety(2.76) and first-aid treatment(2.76), traffic safety(2.71), play and leisure safety(2.66) and school safety(2.56). Items showing statistical differences in the degree of safety consciousness according to demographical characteristics were sex(t=-3.11, p=.002), education(t=2.33, p=.021) and number of siblings(F=3.729, p=.011). In the difference of safety consciousness between both sexes, 'female' students(2.75) showed higher safety consciousness than 'male' students (2.69), and the former also showed higher safety consciousness than the latter in all six areas of school safety, play and leisure safety, traffic safety, fire safety, home safety and first-aid treatment, and there were statistical differences in the areas of play and leisure safety, traffic safety, fire safety and first-aid treatment. According to the differences of safety consciousness by grade, 'the fifth graders'(2.74) showed higher safety consciousness than 'the sixth graders'(2.70) and the former also showed higher safety consciousness than the latter in all six areas of school safety, play and leisure safety, traffic safety, fire safety, home safety and first-aid treatment, and there were statistical differences in the areas of fire safety and home safety. In the safety consciousness by the number of siblings, 'single son or daughter' (2.78) was highest and their safety consciousness was also highest in all six areas of school safety, play and leisure safety, traffic safety, fire safety, home safety and first-aid treatment, and there were statistical differences in the areas of school safety, fire safety and home safety, There were statistically remarkable differences in degree of adaptation to school life (F=15.349, p=.000) and perceived schooling level(F=9.552, p=.000). According to the degree of safety consciousness related to characteristics of safety education, there were statistical differences at the degree of recognizing the need of safety education(F=9.797, p=.000), degree of safety education at school(F=2.595, p=.006), degree of safety education by parents(F=12.709, p=.000), degree of practicing safety by parents(F=17.579, p=.000), source of knowledge of safety education (F=2,715, p=.044), necessity of safety education textbooks(F=3.972, p=.008), need of safety teacher(F=4.137, p=.006) and qualification standard of safety teacher(F=3.016, p=.029).

• Journal of Korean Academy of Nursing
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• v.34 no.3
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• pp.485-494
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• 2004

Purpose: This study was aimed to develop a WBI(Web Based Instruction) program on safety for 3rd grade elementary school students and to test the effects of it. Method: The WBI program was developed using Macromedia flash MX, Adobe Illustrator 10.0 and Adobe Photoshop 7.0. The web site was http://www.safeschool.co.kr. The effect of it was tested from Mar 24, to Apr 30, 2003. The subjects were 144 students enrolled in the 3rd grade of an elementary school in Gyungju. The experimental group received the WBI program lessons while each control group received textbook-based lessons with visual presenters and maps, 3 times. Data was analyzed with descriptive statistics, and ${\chi}^2$test, t-test, and repeated measure ANOVA. Result: First, the WBI group reported a longer effect on knowledge and practice of accident prevention than the textbook-based lessons, indicating that the WBI is more effective. Second, the WBI group was better motivated to learn the accident prevention lessons, showing that the WBI is effective. As a result, the WBI group had total longer effects on knowledge, practice and motivation of accident prevention than the textbook-based instruction. Conclusion: We recommend that this WBI program be used in each class to provide more effective safety instruction in elementary schools.

• Journal of the Korea Institute of Building Construction
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• v.12 no.6
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• pp.586-595
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• 2012

While the extruded cement panel has many advantages compared to drywall, it has limited applicability in buildings due to its low fire resistance. However, an extruded panel in which the fire resistance has been dramatically enhanced through the addition of a-hemihydrate gypsum is expected to become widely applied as a partition wall or interior material for buildings. To ensure its applicability, certain safety requirements for use, such as the leaning load by residents, the impact by indoor articles, and the fire, need to be taken into consideration. The purpose of this study is to review the impact load resistance, horizontal load resistance, and fire resistance as required safety properties for the partition wall and interior materials of the extruded panel that includes a-hemihydrate gypsum. The results of this study show that the impact load resistance of the extruded panel that includes a-hemihydrate gypsum achieves SD grade for industrial buildings, and the horizontal impact load resistance achieves HD grade for public buildings. In addition, it provides fire-resistance for approximately 7 minutes longer than the existing extruded cement panel. Based on this result, it is confirmed the extruded panel incorporating a-hemihydrate gypsum has adequate safety properties for use as partition wall or interior material.

• Journal of the Korean Society of Safety
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• v.23 no.5
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• pp.73-78
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• 2008

The fire hazards and combustion heat of puzzle mats in group day care home were analysed using variable external irradiation level. The fire hazards such as ignition time, ignition temperature, mass loss rate, and flame temperature profile were measured. Incident heat fluxes of $15kW/m^2$, $20kW/m^2$, $25kW/m^2$, $35kW/m^2$, $50kW/m^2$ and $75kW/m^2$ were selected for these experiments. All samples were tested in the horizontal orientation and were wrapped in a single layer of aluminium foil. Each sample was nominally 20mm thick and 100mm square. Five samples of puzzle mat were tested in the study : Type A, B, C, D and E. Type A, B and C are all general grades whereas Type D and E are both Flame retardant grades. As results, Type E of FR-grade showed the best characteristics in safety of the early fire from ignition time, critical heat flux, and ignition and flame temperature data of this study. All specimen of G-grade(Type A, B and C), however, showed the weak in safety of fire.

• Journal of The Korean Society of Agricultural Engineers
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• v.64 no.5
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• pp.17-26
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• 2022

In this study, in order to establish the criteria for evaluation of importance by the type of facility specialized for agricultural reservoirs, an expert group consisting of a total of 167 members who were in management, or specialized in the fields of design, research, and diagnosis were organized, and the importance for facilities was set with application of the AHP technique. The importance of dam body, spillway, and intake structure composing a reservoir were set at 59%, 24%, and 17%, and the importance of dam crest, upstream slope, and downstream slope constituting a dam body was set at 32%, 31%, and 37%, respectively. In addition, the importance of approach channel, regulated channel, chute channel, and stilling basin consisting a spillway was set at 15%, 44%, 26%, and 15%, and the importance of inclined conduit and outlet conduit consisting an intake structure was set at 35% and 65%, respectively. The safety grade of the reservoirs evaluated by applying the newly presented importance values in this study showed the rearrangement of the grades with a change of 11% compared to the previous grades. In this way, the newly established criteria are expected to be utilized as basic data with strategic importance in reservoir safety management and disaster prevention as well as the operation of systems in the future.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.43 no.3
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• pp.397-411
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• 2023

The number of deteriorated bridges with a service period of more than 30 years has been rapidly increasing in Korea. Accordingly, the importance of advanced maintenance technologies through the predictions of age-induced deterioration degree, condition, and performance of bridges is more and more noticed. The prediction method of the safety grade of bridges was proposed in this study using the classification models of the Decision Tree and the Random Forest based on machine learning. As a result of analyzing these models for the 8,850 bridges located in national roads with various evaluation indexes such as confusion matrix, balanced accuracy, recall, ROC curve, and AUC, the Random Forest largely showed better predictive performance than that of the Decision Tree. In particular, random under-sampling in the Random Forest showed higher predictive performance than that of other sampling techniques for the C and D grade bridges, with the recall of 83.4%, which need more attention to maintenance because of the significant deterioration degree. The proposed model can be usefully applied to rapidly identify the safety grade and to establish an efficient and economical maintenance plan of bridges that have not recently been inspected.

• Journal of the Korean Society of Marine Environment & Safety
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• v.5 no.2
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• pp.57-65
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• 1999

The in situ observations and the seawater analyses were conducted at all seasons from July 1996 to April 1999 for the purpose of describing the characteristics of seasonal variations of water quality in Mokpo harbour, Korea. Vertical stratification started to be formed in water column in spring, developed in summer and disappeared in fall. In summer, vertical density distribution of water column was found to be in stable structure with lower temperature and higher salinity of bottom water, and the vertical mixing of water between surface and bottom layers was restricted. In winter, however, surface water was found to be similar to bottom water in temperature and salinity, and water column was in unstable structure and in well-mixed condition between surface and bottom waters. The saturation percentage of dissolved oxygen(DO) in bottom water of inner part of Mokpo harbour at all seasons was shown to be decreased to the third grade or under the third grade of Korean standards of seawater quality. In particular, dissolved oxygen was oversaturated in surface water and undersaturated in bottom water in summer, due to stratification and organic pollution. The difference of DO concentration between surface and bottom waters was found to be greater in spring and summer than in fall and winter, due to stratification and photosynthesis of phytoplankton. The concentrations of chemical oxygen demand(COD) over the entire waters of Mokpo harbour were found to fluctuate from below the third grade to the first grade of Korean standards through all seasons and COD concentrations of same seasons were shown to be different year after year. In particular, in view of COD, the annual average seawater quality of Mokpo harbour was evaluated to be in third grade of Korean standards, due to organic pollution. The average COD of surface water was greater than that of bottom water in spring and summer, due to the autochthonous COD caused by production of phytoplankton in surface waters, while the average COD of surface water was similar to that of bottom water in fall and winter, due to the vertical mixing of water between surface and bottom layers.

• Journal of Korean Society of Transportation
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• v.13 no.2
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• pp.43-58
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• 1995

This paper discusses some of the results of investigation of railroad-highway grade crossing accidents and accident-related inventory information that was collected from the Pusan District Office of the Korean National Railroads. Established statistical techniques were applied to tabulated data to obtain an accident prediction equation that estimates the expected probability of accidents at each crossing under various grade crossing situations. It was found that the most significant factor that influences the railroad crossing accidents was flagger. The other factors were train and traffic volumes, number of tracks. crossing angle, maximum timetable train speed, algebraic grade difference, and lighting facility. No significant effects was identified with railroad crossing gates. The results of the analysis and the uses of the prediction equation for the development of warrants for safety improvements are also discussed.

• Journal of the Korean Society of Marine Environment & Safety
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• v.28 no.5
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• pp.735-745
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• 2022

In this study, a health assessment was conducted using the Benthic Health Index (BHI) to assess fish cage farms, where a fishery environment assessment was also performed. A total of 43 farms were evaluated located in the East Sea, West Sea, and South Sea in Korea. The results of the BHI health evaluation included 8 grade 1 farms, 4 grade 2, 12 grade 3, and 19 grade 4. The grade 1 farms included sandy sediment farms and those with low intensity aquaculture, while the grade 2 farms included those located in areas with active seawater circulation. The fish cage farms belonging to grade 3 and 4 included the majority of farms with high-intensity aquaculture activities. There was no significant difference in total organic carbon between grade 3 and 4 farms, but the results of polychaete community analysis show that organic matter concentration was significantly higher in grade 4 farms.