• Title/Summary/Keyword: damage estimation

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Analysis of Crop Survey Protocols to Support Parameter Calibration and Verification for Crop Models of Major Vegetables (주요 채소 작물 대상 작물 모형 모수 추정 및 검증을 지원하기 위한 생육 조사 프로토콜 분석)

  • Kim, Kwang Soo;Kim, Junhwan;Hyun, Shinwoo
    • Korean Journal of Agricultural and Forest Meteorology
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    • v.22 no.2
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    • pp.68-78
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    • 2020
  • Crop models have been used to predict vegetable crop yield, which would have a considerable economic impact on consumers as well as producers. A small number of models have been developed to estimate growth and yield of vegetables due to limited availability of growth observation data in high-quality. In this study, we aimed to analyze the protocols designed for collection of the observation data for major vegetable crops including cabbage, radish, garlic, onion and pepper. We also designed the protocols suitable for development and verification of a vegetable crop growth model. In particular, different measures were proposed to improve the existing protocol used by Statistics Korea (KOSTAT) and Rural Development Administration (RDA), which would enhance reliability of parameter estimation for the crop model. It would be advantageous to select sampling sites in areas where reliable weather observation data can be obtained because crop models quantify the response of crop growth to given weather conditions. It is recommended to choose multiple sampling sites where climate conditions would differ. It is crucial to collect time series data for comparison between observed and simulated crop growth and yield. A crop model can be developed to predict actual yield rather than attainable yield using data for crop damage caused by diseases and pests as well as weather anomalies. A bigdata platform where the observation data are to be shared would facilitate the development of crop models for vegetable crops.

Aggregate Utilization Estimation of River Sand according to Typical Location of Main Stream of Nakdong-River (낙동강 본류의 대표위치별 하천모래의 골재 활용성 평가)

  • Park, Jae-Im;Bae, Su-Ho;Kwon, Soon-Oh;Kim, Chang-Duk;Lee, Seung-Han
    • Journal of the Korea Academia-Industrial cooperation Society
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    • v.13 no.8
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    • pp.3719-3725
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    • 2012
  • Due to the recent shortage of well-graded river sand resulting from a rapid growth of concrete construction, sea sand, crushed sand, and etc. are increasingly used instead. It is, however, well noted that non-washed sea sand leads to corrosion of the reinforcing steel in concrete, and thus eventually results in damage to concrete. Also, the crushed sand is not being widely used, since it is difficult to maintain the allowable amount of passing 0.08mm sieve and to adjust grading. On the other hand, because the fine sand of Nakdong-River has a poor grading but good quality as a fine aggregate for concrete, it is strongly needed to investigate the fine sand as an alternative fine aggregate. Thus, the purpose of this research is to evaluate the physical properties of the fine sand of Nakdong-River to utilize it actively as a fine aggregate. For this purpose, after the sand samples were collected according to typical location of main stream of Nakdong-River, the physical properties such as density in oven-dry condition, grading, unit volume mass, and etc. of them were estimated. It was observed from the test results that physical properties of the fine sand of Nakdong-River except grading were found to be excellent.

Comparison of the flow estimation methods through GIUH rainfall-runoff model for flood warning system on Banseong stream (반성천 홍수경보 시스템을 위한 GIUH기반 한계홍수량 산정기법 비교연구)

  • Seong, Kiyoung;Ahn, Yujin;Lee, Taesam
    • Journal of Korea Water Resources Association
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    • v.54 no.5
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    • pp.347-354
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    • 2021
  • In the past few years, various damages have occurred in the vicinity of rivers due to flooding. In order to alleviate such flood damage, structural and non-structural measures are being established, and one of the important non-structural measures is to establish a flood warning system. In general, in order to establish a flood warning system, the water level of the flood alarm reference point is set, the critical flow corresponding thereto is calculated, and the warning precipitation amount corresponding to the critical flow is calculated through the Geomorphological Instantaneous Unit Hydrograph (GIUH) rainfall-runoff model. In particular, when calculating the critical flow, various studies have calculated the critical flow through the Manning formula. To compare the adequacy of this, in this study, the critical flow was calculated through the HEC-RAS model and compared with the value obtained from Manning's equation. As a result of the comparison, it was confirmed that the critical flow calculated by the Manning equation adopted excessive alarm precipitation values and lead a very high flow compared to the existing design precipitation. In contrast, the critical flow of HEC-RAS presented an appropriate alarm precipitation value and was found to be appropriate to the annual average alarm standard. From the results of this study, it seems more appropriate to calculate the critical flow through HEC-RAS, rather than through the existing Manning equation, in a situation where various river projects have been conducted resulting that most of the rivers have been surveyed.

Estimation of Inundation Area by Linking of Rainfall-Duration-Flooding Quantity Relationship Curve with Self-Organizing Map (강우량-지속시간-침수량 관계곡선과 자기조직화 지도의 연계를 통한 범람범위 추정)

  • Kim, Hyun Il;Keum, Ho Jun;Han, Kun Yeun
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.38 no.6
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    • pp.839-850
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    • 2018
  • The flood damage in urban areas due to torrential rain is increasing with urbanization. For this reason, accurate and rapid flooding forecasting and expected inundation maps are needed. Predicting the extent of flooding for certain rainfalls is a very important issue in preparing flood in advance. Recently, government agencies are trying to provide expected inundation maps to the public. However, there is a lack of quantifying the extent of inundation caused by a particular rainfall scenario and the real-time prediction method for flood extent within a short time. Therefore the real-time prediction of flood extent is needed based on rainfall-runoff-inundation analysis. One/two dimensional model are continued to analyize drainage network, manhole overflow and inundation propagation by rainfall condition. By applying the various rainfall scenarios considering rainfall duration/distribution and return periods, the inundation volume and depth can be estimated and stored on a database. The Rainfall-Duration-Flooding Quantity (RDF) relationship curve based on the hydraulic analysis results and the Self-Organizing Map (SOM) that conducts unsupervised learning are applied to predict flooded area with particular rainfall condition. The validity of the proposed methodology was examined by comparing the results of the expected flood map with the 2-dimensional hydraulic model. Based on the result of the study, it is judged that this methodology will be useful to provide an unknown flood map according to medium-sized rainfall or frequency scenario. Furthermore, it will be used as a fundamental data for flood forecast by establishing the RDF curve which the relationship of rainfall-outflow-flood is considered and the database of expected inundation maps.

3D Reconstruction of Pipe-type Underground Facility Based on Stereo Images and Reference Data (스테레오 영상과 기준데이터를 활용한 관로형 지하시설물 3차원 형상 복원)

  • Cheon, Jangwoo;Lee, Impyeong
    • Korean Journal of Remote Sensing
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    • v.38 no.6_1
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    • pp.1515-1526
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    • 2022
  • Image-based 3D reconstruction is to restore the shape and color of real-world objects, and image sensors mounted on mobile platforms are used for positioning and mapping purposes in indoor and outdoor environments. Due to the increase in accidents in underground space, the location accuracy problem of underground spatial information has been raised. Image-based location estimation studies have been conducted with the advantage of being able to determine the 3D location and simultaneously identify internal damage from image data acquired from the inside of pipeline-type underground facilities. In this study, we studied 3D reconstruction based on the images acquired inside the pipe-type underground facility and reference data. An unmanned mobile system equipped with a stereo camera was used to acquire data and image data within a pipe-type underground facility where reference data were placed at the entrance and exit. Using the acquired image and reference data, the pipe-type underground facility is reconstructed to a geo-referenced 3D shape. The accuracy of the 3D reconstruction result was verified by location and length. It was confirmed that the location was determined with an accuracy of 20 to 60 cm and the length was estimated with an accuracy of about 20 cm. Using the image-based 3D reconstruction method, the position and line-shape of the pipe-type underground facility will be effectively updated.

Estimation of the Hydrological Design Frequency of Local Rivers Using Bayesian Inference and a Sensitivity Analysis of Evaluation Factors (평가인자 가중치에 대한 베이지안 추론과 민감도 분석을 통한 적정 하천설계빈도 결정)

  • Ryu, Jae Hee;Kim, Ji Eun;Lee, Jin-Young;Park, Kyung-Woon;Kim, Tae-Woong
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.42 no.5
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    • pp.617-626
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    • 2022
  • In Korea, annual precipitation and its variability have gradually increased since modern meteorological observations began, and the risk of disasters has also been increasing due to significant regional variations and recent abnormal climate conditions. Given that damage from storms and floods mainly occurs around rivers, it is crucial to determine the appropriate design frequency for river-related projects. This study examined existing design practices used to determine hydrological design frequencies and suggested a new method to determine appropriate design frequencies. The study collected available data pertaining to seven evaluation factors, specifically the basin areas, shape parameters, channel slopes, stream orders, backwater effect reaches, extreme rainfall frequencies, and urbanized flood inundation areasfor 413 local rivers in Chungcheongnam-do in Korea. The estimated weights for areas of extreme rainfall frequencies and urbanized flood inundation were found to be 18, having a great effect on determining the design frequency. Compared with the established design frequency in previous government reports, the estimated design frequency increased for 255 rivers and decreased for 158 rivers.

The Estimation of Buckling Load of Pressurized Unstiffened Cylindrical Shell Using the Hybrid Vibration Correlation Technique Based on the Experimental and Numerical Approach (실험적/수치적 방법이 혼합된 VCT를 활용한 내부 압력을 받는 원통형 쉘의 좌굴 하중 예측)

  • Lee, Mi-Yeon;Jeon, Min-Hyeok;Cho, Hyun-Jun;Kim, Yeon-Ju;Kim, In-Gul;Park, Jae-Sang
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.50 no.10
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    • pp.701-708
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    • 2022
  • Since the propellant tank structure of the projectile is mainly subjected to a compressive force, there is a high risk of damage due to buckling. Large and lightweight structures such as propellant tank have a complex manufacturing process. So it requires a non-destructive test method to predict buckling load to use the structure after testing. Many studies have been conducted on Vibration Correlation Technique(VCT), which predicts buckling load using the relationship between compressive load and natural frequency, but it requires a large compressive load to predict the buckling load accurately, and it tends to decrease prediction accuracy with increasing internal pressure in structure. In this paper, we analyzed the causes of the decrease in prediction accuracy when internal pressure increases and proposed a method increasing prediction accuracy under the low compressive load for being usable after testing, through VCT combined testing and FEA result. The prediction value by the proposed method was very consistent with the measured actual buckling load.

Soil Depth Estimation and Prediction Model Correction for Mountain Slopes Using a Seismic Survey (탄성파 탐사를 활용한 산지사면 토심 추정 및 예측모델 보정)

  • Taeho Bong;Sangjun Im;Jung Il Seo;Dongyeob Kim;Joon Heo
    • Journal of Korean Society of Forest Science
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    • v.112 no.3
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    • pp.340-351
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    • 2023
  • Landslides are major natural geological hazards that cause enormous property damage and human casualties annually. The vulnerability of mountainous areas to landslides is further exacerbated by the impacts of climate change. Soil depth is a crucial parameter in landslide and debris flow analysis, and plays an important role in the evaluation of watershed hydrological processes that affect slope stability. An accurate method of estimating soil depth is to directly investigate the soil strata in the field. However, this requires significant amounts of time and money; thus, numerous models for predicting soil depth have been proposed. However, they still have limitations in terms of practicality and accuracy. In this study, 71 seismic survey results were collected from domestic mountainous areas to estimate soil depth on hill slopes. Soil depth was estimated on the basis of a shear wave velocity of 700 m/s, and a database was established for slope angle, elevation, and soil depth. Consequently, the statistical characteristics of soil depth were analyzed, and the correlations between slope angle and soil depth, and between elevation and soil depth were investigated. Moreover, various soil depth prediction models based on slope angle were investigated, and corrected linear and exponential soil depth prediction models were proposed.

Estimation of the Mechanical Properties of the Concrete Tunnel Lining by Drilling Resistance Test (천공저항시험에 의한 콘크리트 터널라이닝의 역학적 특성 추정)

  • Choi, Soon-Wook;Sung, Yun-Chang;Cheong, Ho-Seop;Chang, Soo-Ho
    • Journal of the Korean Geotechnical Society
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    • v.23 no.11
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    • pp.87-98
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    • 2007
  • For the quick rehabilitation of a fire-damaged tunnel structure, it is the most important procedure to investigate the fire-induced damaged zone rapidly. This study aims to propose a new drilling resistance testing method by which mechanical properties of tunnel concrete lining altered by high temperature can be estimated easily and continuously. Especially, it alms to derive the relationships to estimate mechanical properties of mortar and concrete materials from drilling parameters. To obtain the optimum testing condition, a series of drilling resistance tests were carried out for mortar specimens. When the rotation per minute of drill bit, tile penetration rate and the bit diameter were 1,300 rpm, 1.40 mm/sec, and 10 mm respectively, the deviation of measured drilling resistance forces was minimal. Under the optimum testing condition, the relationships between drilling resistance and mechanical properties of mortar specimens were shown to be very favorable. The concept of replacing a mean value of resistance farces measured during drilling with the resistance energy was proposed to consider the effects of randomly distributed aggregates inside a concrete material on drilling resistance. When the concept was applied to concrete materials, a favorable relationship between actual compressive strength and drilling resistance energy was also successfully derived.

Tunnel-lining Back Analysis Based on Artificial Neural Network for Characterizing Seepage and Rock Mass Load (투수 및 이완하중 파악을 위한 터널 라이닝의 인공신경망 역해석)

  • Kong, Jung-Sik;Choi, Joon-Woo;Park, Hyun-Il;Nam, Seok-Woo;Lee, In-Mo
    • Journal of the Korean Geotechnical Society
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    • v.22 no.8
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    • pp.107-118
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    • 2006
  • Among a variety of influencing components, time-variant seepage and long-term underground motion are important to understand the abnormal behavior of tunnels. Excessiveness of these two components could be the direct cause of severe damage on tunnels, however, it is not easy to quantify the effect of these on the behavior of tunnels. These parameters can be estimated by using inverse methods once the appropriate relationship between inputs and results is clarified. Various inverse methods or parameter estimation techniques such as artificial neural network and least square method can be used depending on the characteristics of given problems. Numerical analyses, experiments, or monitoring results are frequently used to prepare a set of inputs and results to establish the back analysis models. In this study, a back analysis method has been developed to estimate geotechnically hard-to-known parameters such as permeability of tunnel filter, underground water table, long-term rock mass load, size of damaged zone associated with seepage and long-term underground motion. The artificial neural network technique is adopted and the numerical models developed in the first part are used to prepare a set of data for learning process. Tunnel behavior, especially the displacements of the lining, has been exclusively investigated for the back analysis.