• Journal of the Korean Geotechnical Society
• /
• v.26 no.3
• /
• pp.35-45
• /
• 2010

The mechanism of load transfer by punching shear in pile-supported embankments is investigated. Based on the geometric configuration of the punching shear observed in sand fills on soft ground, a theoretical analysis is carried out to predict the embankment loads transferred on a cap beam according to punching shear developed in pile-supported embankments. The equation presented by the theoretical analysis was able to consider the effect of various factors affecting the vertical loads transferred on the cap beam. The reliability of the presented theoretical equation is investigated by comparing it with the results of a series of model tests. The model tests were performed on cap beams, which had two types of width; one is narrow width and the other is wide width. Sand filling was performed through seven steps. Two types of loading pattern were applied at each filling step; one is the long-term loading, in which sand fills at each filling step were kept for 24 hours, the other is the short-term loading, in which sand fills at each filling step were kept for 2 hours. The vertical loads measured in all model tests show good agreement with the ones predicted by the theoretical equation. Finally, the predicted vertical loads also show good agreement with the vertical loads measured in a well-instrumented pile-supported embankment in field, where cap beams were placed on too wide space.

• Journal of the Korean Geotechnical Society
• /
• v.26 no.11
• /
• pp.89-98
• /
• 2010

A method to design a critical height of embankments is presented so as to mobilize fully soil arching in pile-supported embankments. The behavior of the load transfer of embankment weights on pile cap beams was investigated by a series of model tests performed on pile-supported embankments with relatively wide space between cap beams. The model tests explained that the behavior of the load transfer depended very much on the height of embankments, because soil arching could be mobilized in pile-supported embankments only under enough high embankments. The measured vertical loads on cap beams coincided with the predicted ones estimated by the theoretical equations, which have been presented in the previous studies on the basis of load transfer mechanisms according to either the punching shear failure mode during low filling stage or the soil arching failure mode during high filling stage. The mechanism of the load transfer was shifted beyond a critical height of embankment from the punching shear mechanism to the soil arching mechanism. Therefore, in order to mobilize soil arching in pile-supported embankments, the embankments should be designed at least higher than the critical height. A theoretical equation to estimate the critical height could be derived by equalizing the vertical loads estimated by the load transfer mechanisms on the basis of both the punching shear and the soil arching. The derived theoretical equation could predict very well the experimental critical height of embankment.

• Journal of Korea Water Resources Association
• /
• v.55 no.4
• /
• pp.267-278
• /
• 2022

Recently Flood damage volume has increased as heavy rain has frequently occurred. Especially urban areas are a vulnerability to flooding damage because of densely concentrated population and property. A local government is preparing to mitigate flood damage through the heavy rain warning issued by Korea Meteorological Administration. This warning classification is identical for a national scale. However, Seoul has 25 administrative districts with different regional characteristics such as climate, topography, disaster prevention state, and flood damage severity. This study considered the regional characteristics of 25 administrative districts to analyze the flood vulnerability using entropy weight and Euclidean distance. The rainfall classification was derived based on probability rainfall and flood damage rainfall that occurred in the past. The result shows the step 2 and step 4 of rainfall classification was not significantly different from the heavy rain classification of the Korea Meteorological Administration. The flood vulnerability is high with high climate exposure and low adaptability to climate change, and the rainfall classification is low in the northern region of Seoul. It is possible to preemptively respond to floods in the northern region of Seoul based on relatively low rainfall classification. In the future, we plan to review the applicability of rainfall forecast data using the rainfall classification of results from this study. These results will contribute to research for preemptive flood response measures.

• Land and Housing Review
• /
• v.14 no.2
• /
• pp.125-135
• /
• 2023

Drones are used in various fields, including land survey, transportation, forestry/agriculture, marine, environment, disaster prevention, water resources, cultural assets, and construction, as their industrial importance and market size have increased. In this study, image data for deep learning was collected using a mavic3 drone capturing images at a shooting altitude was 20 m with ×7 magnification. Swin Transformer and UperNet were employed as the backbone and architecture of the deep learning model. About 800 sheets of labeled data were augmented to increase the amount of data. The learning process encompassed three rounds. The Cross-Entropy loss function was used in the first and second learning; the Tversky loss function was used in the third learning. In the future, when the crack detection model is advanced through convergence with the Internet of Things (IoT) through additional research, it will be possible to detect patching or potholes. In addition, it is expected that real-time detection tasks of drones can quickly secure the detection of pavement maintenance sections.

• Journal of Digital Convergence
• /
• v.20 no.3
• /
• pp.201-209
• /
• 2022

In order for the military to review the introduction of virtual reality technology into various education and training systems and fully utilize it, it is important to reflect the characteristics of the technology and education system and to accurately identify and selectively apply the characteristics of commercialization. In this study, the evaluation criteria were selected through the Analitic Hierarchy Process (AHP) method for factors to be considered when commercializing a virtual reality-based education and training system, and the priorities of the projects were determined. Based on previous studies, an initial AHP model was constructed and the relative importance of six factors, including reality, was analyzed as the level 1 evaluation criteria. Next, for Level 2, each evaluation criterion was evaluated to confirm the importance of each of the 11 tasks in the six evaluation criteria, and priorities were selected for each task. As a result of the analysis, level 1 showed that reality and ripple had higher importance than other factors. As a result of evaluating the final relative importance, the priority was shown in the order of ① flight training, ② disaster training, ③ shooting Training, and ④ driving a vehicle. Based on the relative priorities determined in Levels 1 and 2 of the model presented in this study, the importance of each project necessary for final decision-making of the research priorities for the defense virtual reality project was presented. It is expected that this study can be used as a reference material for prioritizing the commercialization of education and training systems in the defense sector.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
• /
• v.8 no.9
• /
• pp.265-273
• /
• 2018

In this paper, we propose an acoustic event detection method in tunnels using non-negative tensor factorization (NTF) and hidden Markov model (HMM) applied to multi-channel audio signals. Incidents in tunnel are inherent to the system and occur unavoidably with known probability. Incidents can easily happen minor accidents and extend right through to major disaster. Most incident detection systems deploy visual incident detection (VID) systems that often cause false alarms due to various constraints such as night obstacles and a limit of viewing angle. To this end, the proposed method first tries to separate and detect every acoustic event, which is assumed to be an in-tunnel incident, from noisy acoustic signals by using an NTF technique. Then, maximum likelihood estimation using Gaussian mixture model (GMM)-HMMs is carried out to verify whether or not each detected event is an actual incident. Performance evaluation shows that the proposed method operates in real time and achieves high detection accuracy under simulated tunnel conditions.

• Journal of agriculture & life science
• /
• v.50 no.5
• /
• pp.111-120
• /
• 2016

The objective of this study was to provide basic information for selecting the right timing and the right place of erosion control of stream on Gyeongsangnam-do. In order to achieve this objective, a total of 526 erosion control dams and 230 mountains stream conservation facilities on the constructed places and construction planned places for the erosion control were investigated on site, forest physiognomy, and hydrologic conditions. The erosion control dams and mountain stream conservation facilities were mostly constructed in the area, which has the sedimentary rock, 200-400m of altitude, a slope of 21~30°, and II of landslide hazard map. Among the forest environmental factors, it was only similar to the construction frequency in the areas that have small diameter class, III age class. Also, we investigated the hydrological environmental factors that determine the size and numbers of erosion control dam. The places constructed to the highest frequency were below 50ha in the area, 2.1~4.0km/㎢ of drainage density, longitudinal water system, 61~90mm of maximum precipitation per hour, and 201~300mm of day maximum precipitation. As the results, the sites and floodgate conditions between the constructed places and stream conservation facilities for the erosion control showed to be very similar. Therefore, these results indicate that the erosion control of the stream of the areas, which have the disruption of mountain peaks and the high erosion risk areas, should be used on both the erosion control dam and stream conservation facilities.

• Asia-pacific Journal of Multimedia Services Convergent with Art, Humanities, and Sociology
• /
• v.8 no.4
• /
• pp.285-296
• /
• 2018

Among many hacking attempts carried out in the past few years, the cyber-attacks that could have caused a national-level disaster were the attacks against nuclear facilities including nuclear power plants. The most typical one was the Stuxnet attack against Iranian nuclear facility and the cyber threat targeting one of the facilities operated by Korea Hydro and Nuclear Power Co., Ltd (Republic of Korea; ROK). Although the latter was just a threat, it made many Korean people anxious while the former showed that the operation of nuclear plant can be actually stopped by direct cyber-attacks. After these incidents, the possibility of cyber-attacks against industrial control systems has become a reality and the security for these systems has been tightened based on the idea that the operations by network-isolated systems are no longer safe from the cyber terrorism. The ROK government has established a realistic control systems defense concept and in the US, the relevant authorities have set up several security frameworks to prepare for the threats. This paper presented various cyber security attack cases and their scenarios against control systems, along with the analysis of countermeasures for them. Though this task, we attempt to identify the items that need to be considered when designing a domestic security framework to improve security and secure stability.

• Journal of the Korean BIBLIA Society for library and Information Science
• /
• v.34 no.2
• /
• pp.59-92
• /
• 2023

The purpose of this study is to suggest ways to improve medical librarians' educational programs to improve domestic medical library user services. To this end, the role of medical librarians was investigated, and the education areas were itemized, and then the MLA in the US and the KMLA in Korea were compared and analyzed. As a result, the improvement points for medical librarian education programs in Korea are: First, expansion of certification programs that select various types of education programs, education areas, education contents, and specialized fields, collaboration programs with related institutions, and education programs that advocate the value of KMLA are required. Second, there is a need for various educational programs in the current educational areas, such as 'research support service' and 'education/education design/consultation'. In particular, it is necessary to provide 'consumer health information service' and 'disaster information service' for which there is no education at all. In addition, it is necessary to precede the establishment of regulations on the domestic medical librarian education curriculum for the education of various 'information services in the field related to medicine'. Third, it is necessary to provide online education contents for librarians who have difficulty participating in face-to-face education.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.43 no.1
• /
• pp.139-147
• /
• 2023

As heavy precipitation rates have increased due to climate change, the risk of landslides has also become greater. Studies in the field of disaster risk assessment predominantly focus on evaluating intrinsic importance represented by the use or role of facilities. This work, however, focused on evaluating risks according to the external conditions of facilities, which were presented via debris flow simulation. A random walk model (RWM) was partially improved and used for the debris flow simulation. The existing RWM algorithm contained the problem of the simulation results being overly concentrated on the maximum slope line. To improve the model, the center cell height was adjusted and the inertia application method was modified. Facility information was collected from a digital topographic map layer. The risk level of each object was evaluated by combining the simulation result and the digital topographic map layer. A risk assessment technique suitable for the polygon and polyline layers was applied, respectively. Finally, by combining the evaluated risk with the attribute table of the layer, a system was prepared that could create a list of objects expected to be damaged, derive various statistics, and express the risk of each facility on a map. In short, we used an easy-to-understand simulation algorithm and proposed a technique to express detailed risk information on a map. This work will aid in the user-friendly development of a debris flow risk assessment system.