• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.11
• /
• pp.771-776
• /
• 2020

In this study, the flexural/shear behavior characteristics of perfobond FRP-concrete composite beams using an FRP plate with perforated webs as formwork and reinforcement are analyzed through an analytical method. Compared with the existing experimental results, we have proved its usefulness and use it in future practice. When the nonlinearity is very large in this case, the nonlinear finite element analysis by an explicit method will be effective. The concrete damage plasticity (CDP) model adopted in this study is considered to be able to adequately simulate the nonlinear behavior of concrete, and the determination of several variable factors required in the model is compared with the experimental results and values used in the study. This recommendation will require review and adjustment for more diverse cases. The effect of the perfobond of the composite beam with perforated web is considered to be somewhat effective in terms of securing the initial stiffness, but in the case of the apex, it is considered that the cross-sectional loss and the effect of improving the bonding force should be properly arranged. The contact problem, such as slipping of the FRP plate and concrete, is considered to be one of the reasons that the initial stiffness is slightly larger than the test result, and the slightly difference from the experimental results is attributed to the separation problem between concrete and FRP after the peak.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.11
• /
• pp.843-850
• /
• 2020

The purpose of this study is to evaluate the structural risk and weakness of a railway tank car through nonlinear collision analysis according to overseas collision safety standards. The goal is to propose a crash safety design guideline for railway tank cars for transporting dangerous goods in Korea. We analyzed the buffer impact test procedure of railway freight cars prescribed in EN 12663-2 and the tank puncture test criteria prescribed in 49CFR179. A nonlinear finite element model according to each standard was modeled using LS-DYNA, a commercial finite element analysis solver. As a result of the buffing impact test simulation, it was predicted that plastic deformation would not occur at a collision speed of 6 km/h or less. However, plastic deformation was detected at the rear of the center sill and at the tank center supporting the structure at a collision speed of 8 km/h or more. As a result of a head-on test simulation of tank puncture, the outer tank shell was destroyed at the corner of the tank head when 4% of the kinetic energy of the impacter was absorbed. The tank shell was destroyed in the area of contact with the impacter in the test mode analysis of tank shell puncture when the kinetic energy of the moving vehicle was reduced by 30%. Therefore, the simulation results of the puncture test show that fracture at the tank shell and leakage of the internal material is expected. Consequently, protection and structural design reinforcement are required on railway tank cars in Korea.

• International Journal of Highway Engineering
• /
• v.12 no.1
• /
• pp.1-8
• /
• 2010

Construction of road closed to mountains is inevitable in Korea because the mountainous region in Korea is more than 70% in area. Recently, due to global warming, typhoons or heavy rainfalls frequently occur, and accordingly, mountain roads are seriously damaged by landslides, debris flows, and uplift pressure below pavement. in this study, damage on pavement by uplift pressure was investigated. Various influencing factors such as slope angle, reinforcement of slope surface, thickness of soil cover underlain by rock, and types of drainage system were considered to evaluate uplift pressure acting on the bottom of pavement. Raising of water table up to the surface of slope may depend on the duration and intensity of rainfall. It shows that the installation of subdrain can reduce the uplift water pressure. Therefore, It is concluded that the use of subdrain system is effective to decrease uplift pressure and cement treated base is more endurable than typical crushed-stone base.

• Journal of Science Education
• /
• v.37 no.1
• /
• pp.203-220
• /
• 2013

The purpose of this study was to investigate how 'free inquiry' was implemented in middle school science classrooms. In order to do this, survey and interviews were administered. The subject of survey was 165 science teachers at 58 middle schools and interviewees were 4 teachers and 10 students. As a result, 49.6% of science teachers in school year 2010, and 34.1% in 2011 applied 'free inquiry'. Teachers applied 'free inquiry' during one semester, and they let the students select topic of 'free inquiry'. Teachers grouped students according to students' opinion or their gender and ability, and one group was consisted of 4 students. The effect of applying 'free inquiry' was that students improved the interest on science, science inquiry ability and self directed learning capability. Students were interested in doing 'free inquiry', and they wanted to do it again. Teachers claimed that it took much time and effort to apply 'free inquiry', and students lacked science inquiry skills and interest on science. The teachers who did not apply 'free inquiry' stated reasons such as the shortage of instructional time, and they didn't think that 'free inquiry' should be implemented. For the effective implementation of 'free inquiry', this study suggested that teachers should be recognized the intention of 'free inquiry', teaching-learning materials about 'free inquiry' be developed and provided, and laboratory assistants be employed.

• Journal of Conservation Science
• /
• v.17 s.17
• /
• pp.83-94
• /
• 2005

Host rock or the standing sculptured Buddha in the Yongamsa temple is macular porphyritic biotite granite, which has gone through mechanical and chemical weathering. The rock around the Buddha statue is busily scattered with steep inclinations that are almost vertically discontinuous planes with the strikes of $N8^{\circ}E$. Especially the development of the joints that cross the major joints causes the structural instability of the rock. The rock of the Buddha statue is separated into several rock blocks because of many different discontinuity. Thus it is estimated that the bed rock has not only plane and toppling failure but also wedge failure in all the sides. Since the differential pressure is imposed on the body of the Buddha in the host rock, it is urgent to give a reinforce treatment of geotechnical engineering for the safe of its structural stability. Very contact area of joints have turned into soil, which promotes the growth of weeds and plant roots, then aggravates the mechanical weathering of the rock. Thus conservational treatments should also be considered to get rid of secondary contaminants and vegetation along the discontinuities and to prevent further damages.

• The Journal of Engineering Geology
• /
• v.15 no.2 s.42
• /
• pp.155-168
• /
• 2005

The behavior of earth retention wall installed in a cut slope is different from the behavior of retention wall applied in an urban excavation. In order to establish the design method of anchored retention wall in the cut slope, the behavior of anchored retention wall needs to be investigated and checked in detail. In this study, the behavior of anchored retention wall was investigated by the instrumentation installed in the cut slope, where was stabilized by a row of piles in an apartment construction site. The horizontal displacement of anchored retention wall was larger than the displacement of slope soil behind the wall at the early stage of excavation. As the excavation depth became deeper, the horizontal displacement of slope soil was larger than the displacement of anchored retention wall. It means that the horizontal displacement of anchored retention wall due to excavation is restrained by soldier pile stiffness and jacking force of anchor at the early stage of excavation. lacking force of anchor was mainly influenced on the horizontal displacement of anchored retention wall. The displacements of anchored retention wall and slope soil were affected mainly by rainfall infiltrated from the ground surface. Meanwhile, the horizontal displacement of anchored retention wall with a sloped backside was about $2\~6$ times larger than the displacement of anchored retention wall with a horizontal backside of excavation.

• The Journal of the Korea Contents Association
• /
• v.17 no.4
• /
• pp.12-24
• /
• 2017

This paper analyzed the representation of migrants in television with the example of KBS's My Neighbor, Charles. This primetime TV show with consistent popularity has showcased different types of migrants from other Korean television shows in terms of gender and race, and, partly the difference brought popularity to it. This study finds the major reason of the difference from changed migration patterns in Korea. Until recently, the main population of immigrants in Korea was composed of female brides and workers, but it became diversified to include male and the West migrants. This triggered the changes in media representation, but not thoroughly. Though the faces of migrant protagonists have been diversified, the remaining ideology of nation-centric that has been the main frame to regard migrants as someone to be integrated through traditional values persists. This study finds a few conflicts between the traditional and the change. For example, represented realities of migrants are extends to include their activities in public domain, disputes of multicultural society such as social differentiation and bias, and the criticism of Korean traditional culture. In a gender perspective, while all the marriages represented showed different kinds of vulnerability, discourses of traditional familialism were also clearly presented through different tools of representation. This study aims at contributing existing studies of media representations of migrants with a more complicated pictures in the context of social changes and migration population changes.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.18 no.6
• /
• pp.697-702
• /
• 2017

A preliminary study was carried out to investigate the feasibility of replacing honeycomb cores with pyramidal truss cores in the doors of urban transit railway vehicles. The doors in current operation are sandwich structures comprising a honeycomb core and reinforcements between two facesheets. The structural requirements of doors for urban transit vehicle are specified in the KRS and KRT and standards, according to which the deflections from three-point bending tests must be limited. To this end, two types of pyramidal truss cores with equivalent mass to a honeycomb core were designed. The structural stiffness of doors with pyramidal truss cores and honeycomb cores were numerically calculated via finite element analysis. The three-point bending models were constructed and simulated, and then the calculated deflections were compared with the requirements specified in the regulations. The results show that doors with pyramidal truss cores satisfied the stiffness requirements, although their deflections were 2.5% larger than that of the honeycomb cores. Therefore, the pyramidal truss cores could replace the aluminum honeycomb cores, and their multi-functional capability could be exploited.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.21 no.7
• /
• pp.406-418
• /
• 2020

When developing weapons systems, it is important to implement the functions and performance of equipment suitable for development purposes, but it is very important to ensure that the equipment is capable of operating without any vacuum with reliability after development. Therefore, various activities are carried out to enhance reliability of equipment. Reliability is enhanced by using high-specification parts in development, reliability verification through analysis, and testing using development prototypes to reinforce and improve the parts that are lacking in equipment. However, recently, development schedules are shortened due to rapidly changing external conditions and technologies, and there are cases where sufficient reliability growth activities were not carried out due to problems such as cost. Examples are projects that perform reliability activities only in analytical methods (reliability, FMECA). In this paper, analyzing and testing methods for analysis and testing were carried out on the same equipment through FMECA and super-accelerated life test, the contents of reliability growth activity were derived, the results of design change/review were accordingly compared, the differences between the two methods were analyzed, and measures were proposed to strengthen reliable growth activities. It was concluded that reliable growth activities through analysis from the beginning of development and reliable growth activities through testing should be carried out at the completion of initial prototype production.

• The Journal of the Korea Contents Association
• /
• v.11 no.12
• /
• pp.734-741
• /
• 2011

The beginning that the 'Obstruction of Justice' in the United States is commonly known to Korea is through the impeachment of former president W. J. Clinton in 1998. The 'Obstruction of Justice' in the federal law of the United States is comprehensively provided with a general and a particular rule laying emphasis on the obstruction of legal judiciary proceedings. But, according to the Korean Criminal Act and court decisions, there are no such system like the 'Obstruction of Justice' in the United States. In this result, in terms of the criminal-judicial system, some cases even telling a lies has more benefits than revealing the truth and it is discouraged to cooperate the achievement of judicial justice, which make difficulties in investigation and realizing real truth. For this reason, the Ministry of Justice in Korea makes efforts to introduce the 'Obstruction of Justice'. Nevertheless we should examine from all angles that the introduction of 'Obstruction of Justice' is indeed the alternative in our circumstances. Most of the discussions on the introduction of 'Obstruction of Justice' and also the revised bill of the Ministry of Justice are questions of 'False Statement of Suspect and Witness' for investigation of investigative agency, rather than for the introduction of a general rule on the 'Obstruction of Justice'. The introduction of 'False Statement of Suspect and Witness' for investigation of investigative agency needs to consider concern about human rights infringement and witness protection system should be reinforced in the first place. In other words, the introduction of 'False Statement of Suspect and Witness' for investigation process of investigative agency is undesirable now.