• Title/Summary/Keyword: damage process

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Analysis on the Type of Damaged Land in DeMilitarized Zone(DMZ) Area and Restoration Direction (비무장지대(DMZ) 인근의 훼손지 유형 분석 및 복원방향)

  • Sung, Hyun-Chan;Kim, Su-Ryeon;Kang, Da-In;Seo, Joung-Young;Lee, Sang-Mi
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.19 no.1
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    • pp.185-193
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    • 2016
  • Purpose of this study is to classify damaged lands according to the cause of the damage and their influences based on characteristic of the damaged lands in DeMilitarized Zone(DMZ) area, and utilize this study as a fundamental study for establishment of ecosystem restoration system. Literature review and field survey have been conducted to review the damage status of DMZ area. For field survey, first year and second year have been conducted, in which type of the damage has been reviewed in this study. In the result, types of damage have been classified into 6 categories: 'alteration of initial landform', 'loss of surface layer', 'land pollution', 'alteration of soil chemical property', 'decline of vegetation', and 'invasion of foreign species'. Restoration for each damage type is as following. First, for alteration of initial landform, the land is restored to the original landform prior to the damage and connection to surrounding ecosystem is considered. Second, for loss of surface layer, lost surface layer is restored or further loss is prevented with stabilization. Third, for land pollution, source of the pollution is eradicated or self-circulation with purification of polluted land is encouraged. Fourth, for alteration of soil chemical property, soil is restored of its original property with eradication of the pollution source and improvement of soil. Fifth, for decline of vegetation, current vegetation and anticipated alteration in future are considered and number of wild species is to be increased based on structure and characteristic of nearby vegetation. Sixth, for invasion of foreign species, prevention of dominance by risky species and facilitation ecological stability with ecological management are to be considered. Influence according to the cause of damage has occurred in secondary(indirect) influence or simultaneous occurrence of several damage types. Considering all these aspects, when type of the damage is complex, restoration process for each of former mentioned 6 damage types with solitary influence should be considered in unison.

Analysis on the Damage Status by Diagnostical Methodology for the Improvement Landscape on the Supyo-bridge at Chunggae-stream (청계천 수표교(水標橋)의 경관 향상을 위한 진단학적(診斷學的) 훼손상태 분석)

  • An, Jin-Sung;Choi, Ah-Hyun;Kim, Yu-Il
    • Journal of the Korean Institute of Traditional Landscape Architecture
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    • v.28 no.3
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    • pp.105-113
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    • 2010
  • This study is for the preservation plan of the tradition space which is performed by the damage status analysis through performing the value assessment. Especially, it is an experimental study for finding the process and methods by analyzing the major element for the value assessment of the selected object's damage status through the expert group who are systematized in their interest to conserve the traditional structure in traditional space. For that purpose, this study should be performed by the fundamental understanding of the physical property of the Supyo-bridge and the condition of the selected site's environment. Meanwhile, this study has been done that 'map of the damage status distribution' for making records of damage status of the Supyo-bridge on the property utilized field measurement adapted by photogrammetry and assessment guidelines, which are for investigation on damage status of objects that are standardized 'Raccomandazioni Normal' which could be said construction culture assets management guidelines of Italian government. As the result of investigation, damage status of each part in the Supyo-bridge was mostly composed of damage by sediment and corrosion and in case of 9 damage types including corrosion, in consideration of physical and chemical properties and distribution status of those elements, it is made an judgement that is not working as a threatened factor regarding security of the Supyo-bridge. On the contrary, for the improvement landscape, in case of 'Thermoclastism' phenomenon observed in 'upper floor', 'Myungae stone' and 'bridge pier' is that when taking it into consideration that is widely distributed concentrated on the bridge pier, surface reinforcement job along with elimination of damage part will be judged to be requested for earliest treatment.

Development of Stochastic Decision Model for Estimation of Optimal In-depth Inspection Period of Harbor Structures (항만 구조물의 최적 정밀점검 시기 추정을 위한 추계학적 결정모형의 개발)

  • Lee, Cheol-Eung
    • Journal of Korean Society of Coastal and Ocean Engineers
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    • v.28 no.2
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    • pp.63-72
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    • 2016
  • An expected-discounted cost model based on RRP(Renewal Reward Process), referred to as a stochastic decision model, has been developed to estimate the optimal period of in-depth inspection which is one of critical issues in the life-cycle maintenance management of harbor structures such as rubble-mound breakwaters. A mathematical model, which is a function of the probability distribution of the service-life, has been formulated by simultaneously adopting PIM(Periodic Inspection and Maintenance) and CBIM(Condition-Based Inspection and Maintenance) policies so as to resolve limitations of other models, also all the costs in the model associated with monitoring and repair have been discounted with time. From both an analytical solution derived in this paper under the condition in which a failure rate function is a constant and the sensitivity analyses for the variety of different distribution functions and conditions, it has been confirmed that the present solution is more versatile than the existing solution suggested in a very simplified setting. Additionally, even in that case which the probability distribution of the service-life is estimated through the stochastic process, the present model is of course also well suited to interpret the nonlinearity of deterioration process. In particular, a MCS(Monte-Carlo Simulation)-based sample path method has been used to evaluate the parameters of a damage intensity function in stochastic process. Finally, the present stochastic decision model can satisfactorily be applied to armor units of rubble mound breakwaters. The optimal periods of in-depth inspection of rubble-mound breakwaters can be determined by minimizing the expected total cost rate with respect to the behavioral feature of damage process, the level of serviceability limit, and the consequence of that structure.

High-Velocity Impact Damage Behavior of Carbon/Epoxy Composite Laminates

  • Kim, Young A.;Woo, Kyeongsik;Cho, Hyunjun;Kim, In-Gul;Kim, Jong-Heon
    • International Journal of Aeronautical and Space Sciences
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    • v.16 no.2
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    • pp.190-205
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    • 2015
  • In this paper, the impact damage behavior of USN-150B carbon/epoxy composite laminates subjected to high velocity impact was studied experimentally and numerically. Square composite laminates stacked with $[45/0/-45/90]_{ns}$ quasi-symmetric and $[0/90]_{ns}$ cross-ply stacking sequences and a conical shape projectile with steel core, copper skin and lead filler were considered. First high-velocity impact tests were conducted under various test conditions. Three tests were repeated under the same impact condition. Projectile velocity before and after penetration were measured by infrared ray sensors and magnetic sensors. High-speed camera shots and C-Scan images were also taken to measure the projectile velocities and to obtain the information on the damage shapes of the projectile and the laminate specimens. Next, the numerical simulation was performed using explicit finite element code LS-DYNA. Both the projectile and the composite laminate were modeled using three-dimensional solid elements. Residual velocity history of the impact projectile and the failure shape and extents of the laminates were predicted and systematically examined. The results of this study can provide the understanding on the penetration process of laminated composites during ballistic impact, as well as the damage amount and modes. These were thought to be utilized to predict the decrease of mechanical properties and also to help mitigate impact damage of composite structures.

Damage Analysis of Singly Oriented Ply Fiber Metal Laminate under Concentrated Loading Conditions by Using Acoustic Emission (음향 방출법을 이용한 집중하중을 받는 일방향 섬유 금속 적층판의 손상 해석)

  • 남현욱;김용환;한경섭
    • Composites Research
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    • v.14 no.5
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    • pp.46-53
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    • 2001
  • In this research, damage behavior of singly oriented ply (SOP) fiber metal laminate (FML) subjected to concentrated load was studied. The static indentation tests were conducted to study fiber orientation effect on damage behavior of FML. During the static indentation tests, acoustic emission technique (AE) was adopted to study damage characteristics of FML. AE signals were obtained by using AE sensor with 150kHz resonance frequency and the signals were compared with indentation curves of FML. The damage process of SOP FML was divided by three parts, i.e., crack initiation, crack propagation, and penetration. The AE characteristics during crack initiation show that the micro crack is initiated at lower ply of the plate, then propagate along the thickness of the plate with creating tiber debonding. The crack grow along the fiber direction with occurring 60∼80dB AE signal. During the penetration, the fiber breakage was observed. As fiber orientation increases, talc fiber breakage occurs more frequently. The AE signal behaviors support these results. Cumulative AE counts could well predict crack initiation and crack propagation and AE amplitude were useful for the prediction of damage failure mode.

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Development of Electronic Documents and Management System for Transfer of Disaster Damage and Recovery Information (재난피해복구정보 전자문서 및 관리시스템 개발)

  • Yoon, Hyuk-Jin;Kim, Joo-Sung;Park, Jung-Jun;Chang, Tai-Woo
    • The Journal of Society for e-Business Studies
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    • v.20 no.2
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    • pp.15-26
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    • 2015
  • To prevent the spread of damage, initial reaction and emergency repair are important. But up to now they depend on some guidelines and man power owing to the lack of technical support. In this paper, we described the development process of several electronic documents and information management system of them to rapidly acquire and share damage information of the infrastructure. The damage information, which is acquired by the computer and smart phone, is transformed to the electronic documents and connected to data management system through the damage information acquisition network. These systems could readily be used for preparing a countermeasure of the disaster and disaster recovery.

Computational aspects of guided wave based damage localization algorithms in flat anisotropic structures

  • Moll, Jochen;Torres-Arredondo, Miguel Angel;Fritzen, Claus-Peter
    • Smart Structures and Systems
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    • v.10 no.3
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    • pp.229-251
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    • 2012
  • Guided waves have shown a great potential for structural health monitoring (SHM) applications. In contrast to traditional non-destructive testing (NDT) methodologies, a key element of SHM approaches is the high process of automation. The monitoring system should decide autonomously whether the host structure is intact or not. A basic requirement for the realization of such a system is that the sensors are permanently installed on the host structure. Thus, baseline measurements become available that can be used for diagnostic purposes, i.e., damage detection, localization, etc. This paper contributes to guided wave-based inspection in anisotropic materials for SHM purposes. Therefore, computational strategies are described for both, the solution of the complex equations for wave propagation analysis in composite materials based on exact elasticity theory and the popular global matrix method, as well as the underlying equations of two active damage localization algorithms for anisotropic structures. The result of the global matrix method is an angular and frequency dependent wave velocity characteristic that is used subsequently in the localization procedures. Numerical simulations and experimental investigations through time-delay measurements are carried out in order to validate the proposed theoretical model. An exemplary case study including the calculation of dispersion curves and damage localization is conducted on an exemplary unidirectional composite structure where the ultrasonic signals processed in the localization step are simulated with the spectral element method. The proposed study demonstrates the capabilities of the proposed algorithms for accurate damage localization in anisotropic structures.

Evaluation of Compressive Strengths of Tubular Steel Members According to Corrosion Damage and Shape (원형 강관의 국부 부식손상 수준 및 손상형태에 따른 압축강도 성능평가)

  • Ahn, Jin Hee;Nam, Dong Kyun;Lee, Won Hong;Huh, Jungwon;Kim, In Tae
    • Journal of Korean Society of Steel Construction
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    • v.28 no.4
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    • pp.213-222
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    • 2016
  • For a steel structure with long service period, structural performance can be changed or decreased by corrosion damage occurred under severe corrosion environment condition. In this study, to examine compressive strength and behavior of circular steel member depending on corrosion damage, compressive loading tests were conducted using circular steel member with artificial corrosion damage which was applied by mechanical process and hand drill. From test results, local corrosion area and pattern is related to their structural performance. Their lcoal bucklings were occurred near artificially sectional damaged part. Reduction in compressive strength of circular steel member was also suggested according to their corroded part and damage.

A Quantitative Assessment Model of Private Information Breach (기업의 개인정보 유출로 인한 경제적 피해규모 산출방법)

  • Han, Chang-Hee;Chai, Seung-Wan;Yoo, Byung-Joon;Ahn, Dae-Hwan;Park, Chae-Hee
    • The Journal of Society for e-Business Studies
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    • v.16 no.4
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    • pp.17-31
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    • 2011
  • Damage caused by private information breach causes serious problems and huge social losses. In order to make a better policy that prevents society from suffering from the damage, we have to know about the actual size of damage. So it is needed to develop a quantitative model of private information breach that helps catching the more accurate size of damage. In our study, we suggest a method which calculate not only the costs of damage from firms' perspective but also those from individual and social perspectives. In this process, we refer to methods adopted by JNSA(Japan Network Security Association) and Ponemon Research Institue and modify it with considering our current situation. Also we try to make a new model by using new methods(web traffic analysis, survey, indirect comparison, etc.) and verify it with theories and methods from econometrics, cost accounting and theory of producer.

A Study on Damge Effect from Boiling Liquid Expanding Vapor Explosion(BLEVE) of LPG Charging Facility (LPG 충전소의 BLEVE 현상에 따른 피해효과 분석)

  • Roh Sam-Kew;Kim Tae-Hwan;Ham Eun-Gu
    • Journal of the Korean Institute of Gas
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    • v.3 no.3 s.8
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    • pp.45-50
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    • 1999
  • The LPG refueling station's explosion at Bucheon city was a major accident which with rare frequency of occurrence and large damage effect. Therefore, to prevent similar accident in the future from LPG charging stations which located in urban area. It needs to identify the damage effects of such facilities by comparing theoretically quantities risk and actual damage. The BLEVE effects from the accident showed similar damage effect in case of heat flux, however, the overpressure level reflected at the reduced distance by $15\%$. The structure damage to the near by area showed comparatively large heat radiation damage to the concrete structure strength and shape changes through heat flux while the overpressure effect was small.

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