• Title/Summary/Keyword: Collapse Moment

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Study on Suggestion a Standard Installation for Damage Reduction alarm System using Cut-Slope Data (국내 도로절개면 현황 및 붕괴 분석을 통한 경보시스템 설치 기준에 관한 기초적 연구)

  • Bae, Gyu-Jin;Koo, Ho-Bon;Baek, Yong
    • The Journal of Engineering Geology
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    • v.12 no.1
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    • pp.53-61
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    • 2002
  • Cut-slope due to the road construction is one of the most significant problems in the domestic case, that is, 70% of the land is covered by mountain. Moreover, typhoons or heavy rains concentrated in summer season causes the failure of cut-slope. Rock-fall and soil slope failure take 40.8% and 29.5% out of the entire domestic cut-slope failure, respectively. Rock-fall is quickly occurred by the free fall or rolling of rock fragments generally in the upper slope. Soil slope failure produces a clastics-flow and increases casualty especially when caused by heave rainfall because the velocity of the movement is verb high. Considering the car speed and rock-fall velocity, it will take a life in a moment. This study analyzes a set of field data of most recently collapsed domestic road cut-slopes to characterize these cut-slopes and the nature of rock-falls and clastics flows at each site. Based on the results, design criteria for a road alarm system are proposed, considering the relationship between the time required for clastics-flow and the velocity and braking distance of a cat at the incidence. The road alarm system proposed herein would operate instantly after a rock-fall and it will minimize damages, by warning drivels approaching to the collapse or collapsing location in advance.

Reversed Cyclic Load Tests on Deep Beam-and-Exterior Column Joints (깊은보-외부기둥 접합부의 반복 횡하중 실험)

  • Ko, Dong-Woo;Lee, Han-Seon
    • Journal of the Korea Concrete Institute
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    • v.19 no.3
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    • pp.265-273
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    • 2007
  • The most common structural system for apartment buildings in Korea is adopted to combine structural systems: for example, a moment-resisting frame will be used for lower stories and bearing wall system for the upper stories. This type of buildings have soft and/or weak stories in lower stories, and it may lead to collapse of those buildings during the large earthquake. Reversed cyclic load tests were conducted to estimate the performance and behavioral characteristics of deep beam and exterior column Joints. Experimental parameter is the amount of transverse reinforcement (designed by ACI code and Sheikh's procedure). The results of this study are as follows: (1) The required transverse reinforcement of column designed by Sheikh's procedure requires 2.9 times larger than that designed by ACI procedure. Large amount of transverse reinforcement increase the ductility of the column. (2) Most of the lateral drift in the column is due to the flexural deformation in the joint and plastic hinge region and up-lift rotation. (3) Transverse reinforcement in the exterior column shall be required not only in the hinge region but also in the joint.

Full mouth Rehabilitation in a Patient with Occlusal Collapse with Vertical Dimension Increase (교합 붕괴 환자에서 수직 고경을 증가한 보철 수복 : 증례 보고)

  • Jo, Si-Hoon;Jeong, Su-Yang;Nam, Hyun-Seok;Song, Kwang-Yeob;Park, Ju-Mi;Ahn, Seung-Geun
    • Journal of Dental Rehabilitation and Applied Science
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    • v.26 no.4
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    • pp.477-482
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    • 2010
  • In a case of multiple posterior teeth loss, antagonistic teeth extrude to the edentulous space and compensatory occlusion on the remained anterior teeth leads to occlusal trauma. Extrusion of antagonistic teeth breaks down occlusion plane and loss of posterior support bring about severe wear of remained teeth. In this situation, it is needed to restore remained teeth and edentulous space by increasing vertical dimension to obtain prosthodontic rehabilitation space and to correct occlusion plane. In this case report, the patient had a masticatory problem with loss of posterior teeth support and an esthetic problem of shortened anterior teeth. Before the tooth preparation for the prosthodontic restoration, the patient used removable device for 2 months to increase vertical dimension reversibly. After that, he got provisional fixed restoration with irreversible tooth reduction and used it for 3 months. It had spent 5 month to evaluate the adaptation state on final restoration with incresed vertical dimension. The increasing amount was 3 mm, which was relatively in less degree and masticatory system adapted to the increased vertical dimension without any pathologic changes. Final restoration was made to have equal-intensity contacts on all teeth in a verifiable centric relations and immediate disclusion of all posterior contacts the moment the mandible moves in any direction from centric relation. In addition, metal occlusion surface on posterior teeth was applied to prevent excessive muscle activation, occlusal trauma and the porcelain fracture.

A Study on the Optimal Location of the Inclinometer and Strain Gauge in Small-Scale Underground Excavation (소규모 지하굴착에서 지중경사계와 변형률계의 최적 위치 선정에 대한 연구)

  • Gichun Kang;Jinuk Park;Byeongjin Roh;Jiahao Sun;Seong-Kyu Yun
    • Journal of the Korean Geosynthetics Society
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    • v.22 no.2
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    • pp.23-33
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    • 2023
  • Currently, there are cases in Korea where economic damage has occurred due to the ambiguity instrument installation and operation standards in the construction of temporary earth retaining wall, failing to prevent collapse of temporary earth retaining wall at the construction site in advance. Therefore, in this study, a numerical analysis was conducted to find the appropriate installation location of the inclinometer and strain gauge among the installed instruments shown in the design drawing of the temporary earth retaining wall. As a results, It was found that the installation position of the underground inclinometer is the corner of the retaining wall in the case of plane-deformation analysis, and the most displacement occurs in the center of the excavation surface in the case of 3D analysis. When the stress and moment are comprehensively analyzed, the corner is judged to be a vulnerable point. In the case of the strain gauge, In plane-deformation analysis and 3D analysis, the maximum bending stress occurred at the wale connection where the end of the strut and the counter strut are in contact. At this point, it is analyzed that it is necessary to focus on installing and managing the connection to prevent accidents from being vulnerable.

Corporate Default Prediction Model Using Deep Learning Time Series Algorithm, RNN and LSTM (딥러닝 시계열 알고리즘 적용한 기업부도예측모형 유용성 검증)

  • Cha, Sungjae;Kang, Jungseok
    • Journal of Intelligence and Information Systems
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    • v.24 no.4
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    • pp.1-32
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    • 2018
  • In addition to stakeholders including managers, employees, creditors, and investors of bankrupt companies, corporate defaults have a ripple effect on the local and national economy. Before the Asian financial crisis, the Korean government only analyzed SMEs and tried to improve the forecasting power of a default prediction model, rather than developing various corporate default models. As a result, even large corporations called 'chaebol enterprises' become bankrupt. Even after that, the analysis of past corporate defaults has been focused on specific variables, and when the government restructured immediately after the global financial crisis, they only focused on certain main variables such as 'debt ratio'. A multifaceted study of corporate default prediction models is essential to ensure diverse interests, to avoid situations like the 'Lehman Brothers Case' of the global financial crisis, to avoid total collapse in a single moment. The key variables used in corporate defaults vary over time. This is confirmed by Beaver (1967, 1968) and Altman's (1968) analysis that Deakins'(1972) study shows that the major factors affecting corporate failure have changed. In Grice's (2001) study, the importance of predictive variables was also found through Zmijewski's (1984) and Ohlson's (1980) models. However, the studies that have been carried out in the past use static models. Most of them do not consider the changes that occur in the course of time. Therefore, in order to construct consistent prediction models, it is necessary to compensate the time-dependent bias by means of a time series analysis algorithm reflecting dynamic change. Based on the global financial crisis, which has had a significant impact on Korea, this study is conducted using 10 years of annual corporate data from 2000 to 2009. Data are divided into training data, validation data, and test data respectively, and are divided into 7, 2, and 1 years respectively. In order to construct a consistent bankruptcy model in the flow of time change, we first train a time series deep learning algorithm model using the data before the financial crisis (2000~2006). The parameter tuning of the existing model and the deep learning time series algorithm is conducted with validation data including the financial crisis period (2007~2008). As a result, we construct a model that shows similar pattern to the results of the learning data and shows excellent prediction power. After that, each bankruptcy prediction model is restructured by integrating the learning data and validation data again (2000 ~ 2008), applying the optimal parameters as in the previous validation. Finally, each corporate default prediction model is evaluated and compared using test data (2009) based on the trained models over nine years. Then, the usefulness of the corporate default prediction model based on the deep learning time series algorithm is proved. In addition, by adding the Lasso regression analysis to the existing methods (multiple discriminant analysis, logit model) which select the variables, it is proved that the deep learning time series algorithm model based on the three bundles of variables is useful for robust corporate default prediction. The definition of bankruptcy used is the same as that of Lee (2015). Independent variables include financial information such as financial ratios used in previous studies. Multivariate discriminant analysis, logit model, and Lasso regression model are used to select the optimal variable group. The influence of the Multivariate discriminant analysis model proposed by Altman (1968), the Logit model proposed by Ohlson (1980), the non-time series machine learning algorithms, and the deep learning time series algorithms are compared. In the case of corporate data, there are limitations of 'nonlinear variables', 'multi-collinearity' of variables, and 'lack of data'. While the logit model is nonlinear, the Lasso regression model solves the multi-collinearity problem, and the deep learning time series algorithm using the variable data generation method complements the lack of data. Big Data Technology, a leading technology in the future, is moving from simple human analysis, to automated AI analysis, and finally towards future intertwined AI applications. Although the study of the corporate default prediction model using the time series algorithm is still in its early stages, deep learning algorithm is much faster than regression analysis at corporate default prediction modeling. Also, it is more effective on prediction power. Through the Fourth Industrial Revolution, the current government and other overseas governments are working hard to integrate the system in everyday life of their nation and society. Yet the field of deep learning time series research for the financial industry is still insufficient. This is an initial study on deep learning time series algorithm analysis of corporate defaults. Therefore it is hoped that it will be used as a comparative analysis data for non-specialists who start a study combining financial data and deep learning time series algorithm.