• Title/Summary/Keyword: Time of Collapse

Search Result 589, Processing Time 0.023 seconds

Development of 2D inundation model based on adaptive cut cell mesh (K-Flood) (적응적 분할격자 기반 2차원 침수해석모형 K-Flood의 개발)

  • An, Hyunuk;Jeong, Anchul;Kim, Yeonsu;Noh, Joonwoo
    • Journal of Korea Water Resources Association
    • /
    • v.51 no.10
    • /
    • pp.853-862
    • /
    • 2018
  • An adaptive cut-cell grid based 2D inundation analysis model, K-Flood, is developed in this study. Cut cell grid method divides a grid into a flow area and a non-flow area depending the characteristics of the flows. With adaptive mesh refinement technique cut cell method can represent complex flow area using relatively small number of cells. In recent years, the urban inundation modeling using high resolution and fine quality data is increasing to achieve more accurate flood analysis or flood forecasting. K-Flood has potential to simulate such complex urban inundation using efficient grid generation technique. A finite volume numerical scheme of second order accuracy for space and time was applied. For verification of K-Flood, 1) shockwave reflex simulation by circular cylinder, 2) urban flood experiment simulation, 3) Malpasset dam collapse simulation are performed and the results are compared with observed data and previous simulation results.

Shipping Container Load State and Accident Risk Detection Techniques Based Deep Learning (딥러닝 기반 컨테이너 적재 정렬 상태 및 사고 위험도 검출 기법)

  • Yeon, Jeong Hum;Seo, Yong Uk;Kim, Sang Woo;Oh, Se Yeong;Jeong, Jun Ho;Park, Jin Hyo;Kim, Sung-Hee;Youn, Joosang
    • KIPS Transactions on Computer and Communication Systems
    • /
    • v.11 no.11
    • /
    • pp.411-418
    • /
    • 2022
  • Incorrectly loaded containers can easily knock down by strong winds. Container collapse accidents can lead to material damage and paralysis of the port system. In this paper, We propose a deep learning-based container loading state and accident risk detection technique. Using Darknet-based YOLO, the container load status identifies in real-time through corner casting on the top and bottom of the container, and the risk of accidents notifies the manager. We present criteria for classifying container alignment states and select efficient learning algorithms based on inference speed, classification accuracy, detection accuracy, and FPS in real embedded devices in the same environment. The study found that YOLOv4 had a weaker inference speed and performance of FPS than YOLOv3, but showed strong performance in classification accuracy and detection accuracy.

A Study on the Clauses of the Work-Related Disease due to Overwork in the Workmen's Compensation Law (과로로 인한 업무상 질병의 산재보상 인정기준에 관한 연구)

  • Kim, Eun Hee
    • Korean Journal of Occupational Health Nursing
    • /
    • v.6 no.1
    • /
    • pp.23-43
    • /
    • 1997
  • The work-related diseases due to continuous overwork are mainly cerebro- and cardio-vascular ones, which is commonly called 'Karoshi', death from overwork. Many factors are capable for Karoshi : occupational stress in relation to technological renovation and industrial rationalization, competitive social structure, and accumulated fatigue accured to long time or irregular working. And its occurence is on the rise. The World Labor Report 1993 released by ILO, pointed out the diseases related to overwork and stress as one of the most important occupational health problem. In Korea, social awareness of Karoshi is at an infant stage, and reliable statistics for its occurence are not compiled in a convenient manner. Despite the rising Karoshi, there are no reliable clauses in workmen's compensation enough to settle down the disputes. Therefore, it is not uncommon that the Labour Ministry and Civil Court find difficulties in reaching an agreement. This study was intended to provide proper compensation and prevention program for workers by suggesting reasonable compensation clauses for the death from overwork. This study consists of two comparative reviews on the compensaton clauses for the death from overwork. One is to review legal standards of Karoshi among three countries, such as Korea, Japan and Taiwan. The other is to investigate the cases of Karoshi in Korea, 121 cases identified at the Labor Welfare Corperation and the Labour Ministrial process of examination and reexamination, and 73 leading cases at the High Court of Justice. The main findings of the study are as follows : 1. Comparisons of comperative review on compensation clauses for the death from overwork among three countries. 1) All of three countries have the same kinds of disease for compensation, which were cerebro-and cardiao-vascular diseases, while for cardiac disease group, Korea has the smaller number of diseases for compensation than Japan. 2) As for the definition of overwork, the three countries share equally that overload for one week prior to collapse is considered as an important factor, but accumulated chronic fatigue is disregarded. 3) As the basis of overwork, in Japan, there is a tendency to move from the conditions of an ordinary healthy adult to those of the individual concerned in Japan, whereas there is no such concern yet in Korea. 4) All the three countries use a common standard of medical judgement in demonstrating causal relationship between a job and a disease. However, Korea is progressive in the sense that in the case of CVA at worksite, the worker himself has no obligation to prove the cause. 2. The results of a comparative review on excutive decisions by Labor Ministry and judicial decisions by the Court in Korea : A judicial decision is based on the legalistic probability, but a excutive decision is not. Therefore, excutive decisions have such restrictions that : 1) TIA (transitory ischemic cerebral attack) and myocarditis are excluded from compensation, and there is little consistency of decision in the case of cause-unknown death. 2) There is a tendency not to compensate for the death from overwork since the work terms such as repeated long-time working, shift work or night-shift work are not considered as overloading. 3) There is a tendency to regard the conditions of a ordinary healthy adult rather than those of the individual concerned(age, existing diseases, health state, etc.) as the comparative basis of overload. 4) There remains a tendency not to compensate for the death from overwork in the case of collapse occuring out of workplace, on the ground of 'on the course of working' and 'in the cause of accident'. Through the study, the fact manifests itself that Korea's compensation clauses for work-related diseases due to overwork are very restrictive. So, it is necessary to extend the Labor Ministry's clauses of compensation for the death from overwork following to the recent changes of other countries and internal judicial decisions. This is very important in the perspective of occupational health that aims at health promotion of workers including prevention of the Karoshi.

  • PDF

A Study on the Basic Directions for Forest Rehabilitation Programs Considering to Economic and Social Conditions of North Korea (북한의 경제사회적 여건을 고려한 황폐산림복구 기본방향 연구)

  • Park, Kyung Seok;Lee, Seong Youn;Park, So Young
    • Journal of Korean Society of Forest Science
    • /
    • v.100 no.3
    • /
    • pp.423-431
    • /
    • 2011
  • The changes of forest degradation in North Korea have closely been related to political, economic and social conditions at all different times. The deforestation by local people for their livelihood has been accelerated when the recession has been worsened due to the 1990's collapse of socialism and the years of natural disasters, and the fall of the centralized and planned economy system. The serious recession in the 1990's has brought many changes in the North Korean society since the 2000's. Not only the underground economy, but also the market in which personal trades are occurred have been expanded as the distribution system of the planned economy system had fallen. In addition, even many state institutions have also increased timber harvest for export to acquire insufficient foreign currency. Eventually, North Korea felt the limits of utilization of forest resources under socialism then started to seek measures to restore devastated forest, while realizing the need of support from the international society. Therefore, some NGOs of South Korea started to give financial support on building tree nurseries in which seedlings for planting are produced to help the rehabilitation of the degraded forests in North Korea. Therefore, Planning of the basic directions for forest rehabilitation programs considering to economic and social conditions of North Korea are needed based on the successful rehabilitation experience of South Korea in the 1970's. First of all, relationships which was built after collapse of centrally planned economy between districts, businesses and workers must be consider to rehabilitate forests in North Korea. Secondly, due to the nature of forest rehabilitation projects this is very needs voluntary participation of resident for a long time, and then forest rehabilitation projects can create jobs for local resident, they can obtain continuous income on the forest rehabilitation projects field in order to promote resident's work in forest rehabilitation projects. Thirdly, the rate dependence on forests of the residents living must keep the level down by rural development projects going side by side with forest rehabilitation projects. Fourthly, use of exsisting forest management system in North Korea is also needed to ensure administrative power and labor for grand scale plantations in a short period of time. Meanwhile after the success of Forest Rehabilitation, it is very important to improve exsisting forest management system.

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
    • /
    • v.24 no.4
    • /
    • pp.1-32
    • /
    • 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.

Analysis of Relative Settlement Behavior of Retaining Wall Backside Ground Using Clustering (군집분류를 이용한 흙막이 벽체 배면 지반의 상대적 침하거동 분석)

  • Young-Jun Kwack;Heui-Soo Han
    • The Journal of Engineering Geology
    • /
    • v.33 no.1
    • /
    • pp.189-200
    • /
    • 2023
  • As urbanization and industrialization increase development in downtown areas, damage due to ground settlement continues to occur. Building collapse in urban has a high risk of leading to large-scale damage to life and property. However, there has rarely been studied on measurement data analysis methods when uneven loads are applied to the excavated ground and no prior knowledge of the ground. Accordingly, it was attempted to analyze the relative settlement behavior and correlation by processing the time-series surface settlement of construction sites in the urban. In this paper, the average index of difference in settlement and average of relative difference in settlement are defined and calculated, then plotted in the coordinate system to analyze the relative settlement behavior over time. In addition, since there was no prior knowledge of the ground, a standard to classify the clusters was needed, and the observation points were classified into using k-means clustering and Dunn Index. As a result of the analysis, it was confirmed that all the clusters moved to the stable region as the settlement amount converges. The clusters were segmented. Based on the analysis results, it was possible to distinguish between the independent displacement area and same behavior area by analyzing the correlation between measurement points. If possible to analyze the relative settlement behavior between the stations and classify the behavior areas, it can be helpful in settlement and stability management, such as uplift of the surrounding area, prediction of ground failure area, and prevention of activity failure.

The Natural hazards and Drought Periodicity during the Medieval Times in Korea Based on the History of Goryeo(Goryeosa) (고려사를 통해 본 한국 중세의 자연재해와 가뭄주기)

  • YOON, Soon-Ock;HWANG, Sangill
    • Journal of The Geomorphological Association of Korea
    • /
    • v.17 no.4
    • /
    • pp.85-98
    • /
    • 2010
  • The natural hazards such as droughts, floods and frost injuries, and their relationships with the social unrest phenomena such as years of famine, smallpox and revolutions during the Medieval times(AD 936~1391) in Korea are compared and analyzed based on the History of Goryeo containing astronomical weather and climate events during the Goryeo Dynasty. Among the natural hazards during the Goryeo Dynasty, the droughts with a period of 4~5 years on average are recorded most frequently. By time series analysis, the most frequency of droughts can be found in AD 286~335, AD 786~835 and AD 1261~1320 during the Ancient and Medieval times. It is suggested that three cycles of the droughts during approximately 1,500 years of the Ancient and Medieval times are recognized and they had happened with the time intervals of approximately 500 years. The frequency of droughts increased in the late Goryeo Dynasty is consistent with those of the social chaos factors such as years of famines, smallpox and revolutions. These records suggest that the natural hazard such as years of famines was one of the most important factors influencing on the collapse of the Goryeo Dynasty, agrarian country.

A Terrain Data Acquisition for Slope Safety Inspection by Using LiDAR (지상 LiDAR에 의한 사면안전진단용 지형정보 취득)

  • Lee, Jong Chool;Kim, Hee Gyoo;Roh, Tae Ho
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
    • /
    • v.31 no.4
    • /
    • pp.311-319
    • /
    • 2013
  • As heavy rains occur more frequently due to the recent climate change, slope collapses are increasing, and damage to human life and properties is accordingly increasing every year. The most proper method to take preventive measures against slope collapses is to remove the cause after understanding the cause of slope collapse in advance, and for such, slope safety inspection is implemented for preventive purposes, to investigate the cause, and as a measure for restoration. Thus, this Research was able to reach the following conclusion after utilizing LiDAR, which obtains detailed topographic information in a short period of time with point cloud data on slopes subject to safety inspection. First, as a result of analyzing the errors after installing a check point in the subject area, the RMSE of the horizontal location error appeared to be ${\pm}2.2cm$ and the RMSE of the vertical location error appeared to be ${\pm}3.0cm$, which shows a practically satisfactory result. Second, the economic feasibility was outstanding and obtaining accurate topographic information was available. Third, an area once scanned allowed to accurately obtain an unprescribed cross-sectional diagram in a short period of time, thus, appeared to be convenient for experts to detect dangerous sections.

A Study on the Change of Cavity Area through Groundwater Injection Test under Pavement Cavity (도로하부 공동 내의 지하수 주입 실험을 통한 공동 영역 변화 연구)

  • Kim, Sang Mok;Choi, Hyeon;Yoon, Jin Sung;Park, Jeong Jun
    • Journal of the Society of Disaster Information
    • /
    • v.16 no.2
    • /
    • pp.267-275
    • /
    • 2020
  • Purpose: In this study, GPR exploration equipment, spray vehicles and flow meters, core drill, borehole image processing system(BIPS), 3D cavity imagery equipment, and cavity formatting equipment were used to identify this cavity growth process. Method: A certain amount of water was injected in proportion to the mass of the cavity, and the cavity was observed to expand as the injected water was drained out. The cavity rating change was evaluated by quantitatively evaluating the expansion factors and the speed of growth. Results: According to the results of examining the volume change through injection time - injection flow rate - volume increase for the four experimenters, the volume increase decreased as the injection time increased, and there was no further increase in volume if injected for one hour or so. Conclusion: In addition, the injection test analyzed the volumetric variation to determine whether the cause of the cavity occurrence was the effect of the underground burial in the vicinity of the cavity. Therefore, it was found that the cavity expansion is caused by the repetition of the relaxation soil collapse due to the groundwater flow and the loss of the collapsed soil below the cavity.

Seismic Performance of Gravity-Load Designed Post-Tensioned Flat Plate Frames (중력하중으로 설계된 포스트텐션 플랫플레이트 골조의 내진성능)

  • Han, Sang-Whan;Park, Young-Mi;Rew, Youn-Ho
    • Journal of the Earthquake Engineering Society of Korea
    • /
    • v.14 no.3
    • /
    • pp.31-38
    • /
    • 2010
  • The purpose of this study is to evaluate the seismic performance of gravity-designed post tensioned (PT) flat plate frames with and without slab bottom reinforcement passing through the column. In low and moderate seismic regions, buildings are often designed considering only gravity loads. This study focuses on the seismic performance of gravity load designed PT flat plate frames. For this purpose, 3-, 6- and 9-story PT flat plate frames are designed considering only gravity loads. For reinforced concrete flat plate frames, continuous slab bottom reinforcement (integrity reinforcement) passing through the column should be placed to prevent progressive collapse; however, for the PT flat plate frames, the slab bottom reinforcement is often omitted since the requirement for the slab bottom reinforcement for PT flat plates is not clearly specified in ACI 318-08. This study evaluates the seismic performance of the model frames, which was evaluated by conducting nonlinear time history analyses. For conducting nonlinear time history analyses, six sets of ground motions are used as input ground motions, which represent two different hazard levels (return periods of 475 and 2475 years) and three different locations (Boston, Seattle, and L.A.). This study shows that gravity designed PT flat plate frames have some seismic resistance. In addition, the seismic performance of PT flat plate frames is significantly improved by the placement of slab bottom reinforcement passing through the column.