• Title/Summary/Keyword: Debris Analysis

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Analysis of Debris Flow Characteristics Considering Forest Environmental Factors -Focusing on the Case of Mt. Daeryong in 2013- (산림환경인자를 고려한 토석류 발생특성 분석 -2013년 춘천시 대룡산 사례를 중심으로-)

  • Park, Sae-Am;Yu, Gwang-Hyeon;Yoo, Nam-Jae
    • Journal of Industrial Technology
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    • v.35
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    • pp.73-80
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    • 2015
  • This paper is research results of the case study on analyzing the characteristics of debris flow considering forest environmental factors, focusing on occurrence of landslides around Mt. Daeryoung in 2013. Extensive landslide of debris flow, caused by heavy rainfall, occurred around Mt. Daeryoung during July in 2013. Field investigation was carried out to construct the data base about forest environmental factor including topography, soil formations and forest type. Thus, contributing factors to cause the landslide of debris flow were investigated so that damages from landslides could be reduced by establishing proper measures.

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Analysis on the Characteristics of debris flows occurred in Jinbu area of Gangwon Province due to heavy rainfall (2006년 집중호우로 발생된 강원도 진부지역의 토석류 특징 분석)

  • Seo, Heung-Seok;Yune, Chan-Young;Jun, Kyoung-Jea
    • Proceedings of the Korean Geotechical Society Conference
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    • 2009.09a
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    • pp.1041-1050
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    • 2009
  • Many slope failures and debris flows were occurred in Jinbu area of Gangwon Province due to heavy rainfall of much more than 400mm in July, 2006. In the area, although about 3 years passed, valleys and gulleys keep their original form when the events happened. Field investigations were performed on Singi-ri and Bongsan-ri in Jinbu area to examine the characteristics of debris flow as well as slope failure. As the result, debris flows were classified as 3 types according to their characteristics analyzed by field investigations.

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Shape Study of Wear Debris in Oil-Lubricated System with Neural Network

  • Park, Heung-Sik;Seo, Young-Baek;Cho, Yon-Sang
    • KSTLE International Journal
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    • v.2 no.1
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    • pp.65-70
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    • 2001
  • The wear debris is fall off the moving surfaces in oil-lubricated systems and its morphology is directly related to the damage and failure to the interacting surfaces. The morphology of the wear particles are therefore directly indicative of wear processes occurring in tribological system. The computer image processing and artificial neural network was applied to shape study and identify wear debris generated from the lubricated moving system. In order to describe the characteristics of various wear particles, four representative parameter (50% volumetric diameter, aspect, roundness and reflectivity) from computer image analysis for groups of randomly sampled wear particles, are used as inputs to the network and learned the friction condition of five values (material 3, applied load 1, sliding distance 1). It is shown that identification results depend on the ranges of these shape parameters learned. The three kinds of the wear debris had a different pattern characteristics and recognized the friction condition and materials very well by neural network. We discuss how these approach can be applied to condition diagnosis of the oil-lubricated tribological system.

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Umyeon Mountain Debris Flow Movement Analysis Using Random Walk Model (Random Walk Model을 활용한 우면산 토석류 거동 분석)

  • Kim, Gihong;Won, Sangyeon;Mo, Sehwan
    • Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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    • v.32 no.5
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    • pp.515-525
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    • 2014
  • Recently, because of increasing in downpour and typhoon, which are caused by climate changes, those sedimentation disasters, such as landslide and debris flow, have become frequent. Those sedimentation disasters take place in natural slope. In order to predict debris flow damage range within wide area, the response model is more appropriate than numerical analysis. However, to make a prediction using Random Walk Model, the regional parameters is needed to be decided, since the regional environments conditions are not always same. This random Walk Model is a probability model with easy calculation method, and simplified slope factor. The objective of this study is to calculate the optimal parameters of Random Walk Model for Umyeon mountain in Seoul, where the large debris flow has occurred in 2011. Debris flow initiation zones and sedimentation zones were extracted through field survey, aerial photograph and visual reading of debris flow before and after its occurrence via LiDAR DEM.

Prediction and Analysis of Debris Flow with Hydraulic Method (수리학적 방법에 의한 토석류의 발생 예측 및 산정)

  • Lee, Soon-Tak;Muneo, Hirano;Park, Ki-Ho
    • Water for future
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    • v.27 no.2
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    • pp.147-154
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    • 1994
  • The occurrence condition of debris fiow due to rainfall is given by solving the equations for fiow on a slope. The solution shows that a debris fiow will occur on a slope when the accumulated rainfall within the time of concentration exceeds a certain value determined by the properties of the slope. To estimate this critical value, the system analysis technique would be commendable. In this study, a procedure to fine the critical rainfall from the rainfall data whith and without debris flows is proposed. Reliability of this method is verified by applying to the debris flows in Unzen Volcano which recently began to erupt. Discharge of debris flow in a stream is obtained by solving the equation of continuity using the kinematic wave theory and assuming the cross sectional area to be a function of discharge. The computed hydrographs agree weel with the ones observed at the rivers in Sakurajima and Unzen Volcanos. It is found from the derived equation that the runoff intensity of debris flow is in proportion to the rainfall intensity and accumulated rainfall, jointly. This gives a theoretical basis to the conventional method which has been widely used.

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Analysis on Effect of Energy Mitigation by Arrangement of Cylindrical Countermeasures through 3D Debris Flow Numerical Analysis (3차원 토석류 수치해석을 통한 원통형 대책구조물의 배치조건에 따른 에너지 저감효과 분석)

  • Kim, Beom Jun;Yune, Chan-Young
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.43 no.5
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    • pp.621-630
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    • 2023
  • In this study, to investigate an energy reduction effect by field application of cylindrical baffle arrays, the 3D Debris flow numerical analysis was conducted with various baffle configurations for the simulation of a real-scale valley, where the cylindrical baffle arrays were installed. For this, the valley of the watershed was modeled using terrestrial LiDAR data from the real-scale experiment site. Numerical analysis simulated the flow behavior of debris flow and the structures using Smooth Particle Hydrodynamics (SPH) technique of ABAQUS (Ver. 2021). The numerical analysis results that the case without cylindrical baffle arrays had a similar velocity change to that of the real-scale experiment. Also, the installation of baffles significantly reduced the frontal velocity of debris flow. Furthermore, increasing the baffle height increased the downstream energy reduction because of the higher flow impedance of taller baffles.

A Study on the Application of Spectrometric Methods for the Analysis of Lubricant Contaminants and Wear Debris (분광분석법을 이용한 윤활유 오염물 및 마모입자 분석에 있어서의 문제점 고찰)

  • 공호성;한흥구;권오관
    • Tribology and Lubricants
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    • v.15 no.2
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    • pp.131-140
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    • 1999
  • This study dealt with some problems occurred in spectrometric oil analysis that has been popularly used for a machine condition monitoring in various fields of industry. One of the problems is that spectrometric technique could not analyze contaminants of large particle (larger than 10 $\mu\textrm{m}$) in lubricating oils. This limitation caused a serious problem in analyzing lubricated machine conditions since wear debris of large size represents better critical machine conditions. In this work, this problem was found to be solved by using a filtration method prior to spectrometric analysis. Another problem could be that spectrometric analysis is incapable of identifying contaminants. This nay mislead the result seriously in practice. This problem was surveyed by analyzing both various types of industrial lubricants and laboratory simulation tests, and the solutions to the problem were suggested in this work.

Study on the Terrestrial LiDAR Topographic Data Construction for Mountainous Disaster Hazard Analysis (산지재해 위험성 분석을 위한 지상 LiDAR 지형자료 구축에 관한 연구)

  • Jun, Kye Won;Oh, Chae Yeon
    • Journal of the Korean Society of Safety
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    • v.31 no.1
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    • pp.105-110
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    • 2016
  • Mountainous disasters such as landslides and debris flow are difficult to forecast. Debris flow in particular often flows along the valley until it reaches the road or residential area, causing casualties and huge damages. In this study, the researchers selected Seoraksan National Park area located at Inje County (Inje-gun), Gangwon Province-where many mountainous disasters occur due to localized torrential downpours-for the damage reduction and cause analysis of the area experiencing frequent mountainous disasters every year. Then, the researchers conducted the field study and constructed geospatial information data by GIS method to analyze the characteristics of the disaster-occurring area. Also, to extract more precise geographic parameters, the researchers scanned debris flow triggering area through terrestrial LiDAR and constructed 3D geographical data. LiDAR geographical data was then compared with the existing numerical map to evaluate its precision and made the comparative analysis with the geographic data before and after the disaster occurrence. In the future, it will be utilized as basic data for risk analysis of mountainous disaster or disaster reduction measures through a fine-grid topographical map.

Characteristics of Runout Distance of Debris Flows in Korea (한국 토석류의 이동거리 특성)

  • Choi, Dooyoung;Paik, Joongcheol
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.32 no.3B
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    • pp.193-201
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    • 2012
  • In the last decade, heavy rainfall induced debris flow events have been remarkably occurred in Korea. Consequently, debris flow is becoming one of the most dangerous natural phenomena in mountainous area. Understanding and correct predicting of the runout distance of debris flow is an essential prerequisite for developing debris flow hazard map and prevention technology. Based on the simple and widely used sled model, in this study, we analyse the net efficiency of debris flows which is a dimensionless constant (=1/R) and defined by the ratio of the horizontal runout distance L from the debris flow source to deposit and the vertical elevation H of the source above the deposit. The analysis of field data observed in total 238 debris flow events occurred from 2002 to 2011 reveals that the representative value of the net efficiency of debris flows in Korea is 4.3. The data observed in Gangwon province where is the most debris flow-prone area in Korea shows that debris flows in Inje area have the runout distance longer than those in Pyongchang and Gangneung. Overall features of the net efficiency of debris flows observed in the central Korea are similar to those in the southern Korea. The estimation based on aerial photographs and available depositional conditions appears to overestimate the net efficiency compared to estimation based on the field observations, which indicates that appropriate depositional conditions need to be developed for debris flows in Korea.

ANALYSTS OF DAMAGE PROBABILITY FOR COLLISION BETWEEN SPACE DEBRIS AND A SATELLITE IN LOW-EARTH ORBIT (우주파편에 의한 저궤도 위성의 손상확률 분석)

  • Lee, Jae-Eun;Park, Sang-Young;Kim, Young-Rok;Choi, Kyu-Hong;Kim, Eung-Hyun;Kim, Gyu-Sun
    • Journal of Astronomy and Space Sciences
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    • v.24 no.2
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    • pp.135-144
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    • 2007
  • Space environment becomes more hazardous for satellite because of increasing number of space debris. This research is to analyze collision hazards between KOMPSAT 3 in low-earth orbit and space debris generated by the explosion of FengYun satellite on the January 11, 2007. Based on the observed data of the space debris from FengYun satellite, the mass and number distribution of the debris are estimated including undetectable debris from the explosion of FengYun satellite. The spatial density and flux for the space debris can be calculated according to size. This study also brings out the analysis for the assessment of collision probability and damage probability. The algorithm developed in the current paper can be used to estimate the level of risk due to space debris for the satellites that will be launched in the future.