• 한국공간구조학회논문집
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• 제18권4호
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• pp.89-96
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• 2018

The paper presents the damage estimation of bridge structures in Daegu city based on the scenario-based earthquakes. Since the fragility curves for domestic bridge strucures are limited, the Hazus methodology is employed to derive the fragility curves and estimate the damage. A total of four earthuquake scenarios near Daegu city are assumed and structure damage is investigated for 81 bridge structures. The seismic fragility function and damage level of each bridge had adopted from the analytical method in HAZUS and then, the damage probability using seismic fragility function for each bridge was evaluated. It was concluded that the seismic damage to bridges was higher when the magnitude of the earthquake was large or nearer to the epicenter.

• 한국방재안전학회논문집
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• 제13권4호
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• pp.13-24
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• 2020

최근 급속한 경제발전과 온난화로 인해 이상기후 현상이 빈번하게 발생하고 있다. 자연재난의 유형 중 풍수해에 해당되는 호우, 태풍, 강풍, 풍랑, 대설 등은 대규모 인적·물적 피해를 발생시킨다. 피해를 최소화하기 위해서는 재난발생 전 피해규모를 예측하는 것이 중요하다. 본 연구는 풍수해의 재난유형 중 강풍피해를 중심으로 재난에 대비할 수 있는 강풍피해예측함수를 개발한다. 본 함수는 재해 연보의 강풍피해이력을 기반으로 기상요소와 지역적 특성을 반영하였으며, 기상정보를 실시간으로 수집할 수 있는 시스템에 탑재할 경우 단시간에 피해규모를 예측할 수 있다. 또한, 본 함수는 국가 혹은 지자체에서 수립하는 재난관리정책에 근거자료로 활용하여 강풍발생 시 피해를 최소화할 수 있다.

• Nuclear Engineering and Technology
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• 제48권5호
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• pp.1280-1290
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• 2016

This paper presents an advanced estimation method for obtaining the probability density functions of a damage parameter for valve leakage detection in a reciprocating pump. The estimation method is based on a comparison of model data which are simulated by using a mathematical model, and experimental data which are measured on the inside and outside of the reciprocating pump in operation. The mathematical model, which is simplified and extended on the basis of previous models, describes not only the normal state of the pump, but also its abnormal state caused by valve leakage. The pressure in the cylinder is expressed as a function of the crankshaft angle, and an additional volume flow rate due to the valve leakage is quantified by a damage parameter in the mathematical model. The change in the cylinder pressure profiles due to the suction valve leakage is noticeable in the compression and expansion modes of the pump. The damage parameter value over 300 cycles is calculated in two ways, considering advance or delay in the opening and closing angles of the discharge valves. The probability density functions of the damage parameter are compared for diagnosis and prognosis on the basis of the probabilistic features of valve leakage.

• 한국항해항만학회:학술대회논문집
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• 한국항해항만학회 2005년도 추계학술대회 논문집
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• pp.297-302
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• 2005

In this paper, an estimating damage on external surface of container using Capsize-Gaussian-Function (be called CGF) is presented. The estimation of the damage size can be get directly from two parameters of CGF, these are the depth and the flexure, also the direction of damage. The performance of the present method has been illustrated using an image of damage container, which had been taken from Hanjin Busan Port, after using image processing techniques to do preprocessing of the image, especially, the main used technique is Canny edge detecting that is widely used in computer vision to locate sharp intensity and to find object boundaries in the image, then correlation between the edge image from the preprocessing step and the CGF with three parameters (direction, depth, flexure), as a result, we get an image that perform damage information, and these parameters is an estimator directly to the damage.

• 한국재난정보학회 논문집
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• 제16권2호
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• pp.223-236
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• 2020

연구목적: 본 연구에서는 재난관리(예방-대비-대응-복구) 중 대비차원으로 활용하고자 강풍피해예측함수를 개발하였다. 연구방법: 본 연구에서 제안하는 강풍피해예측함수는 재해연보이력, 피해당시 기상자료 그리고 지역특성을 고려하였다. 기상자료는 기상청에서 관측한 풍속과 기온, 피해이력에 해당하는 통계자료는 재해연보, 그리고 지역특성을 반영하기 위한 요소로는 재해연보 상 수록된 복구비, 인구, 비닐하우스 면적, 농가수 등을 활용하였다. 연구결과: 본 연구에서 개발한 함수식은 과거에 발생한 강풍피해이력을 기반으로 예측되는 기상인자와 지역특성을 반영하였으며, 단시간에 피해규모를 예측할 수 있다. 결론: 본 연구에서 개발한 강풍피해예측함수는 정책결정자들의 의사결정, 비상인력 및 방재자원의 배치 등과 같은 효율적인 재난관리에 활용할 수 있을 것으로 판단된다.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 추계학술대회
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• pp.307-312
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• 2003

The object of this study is to investigate a damage estimation of single edge cracked tensile specimens ($2_a$/W) as a function of acoustic emission (AE) according to the unidirectionally oriented carbon/epoxy composites, CFRP AE signals were analyzed and classified 3 regions by event counts, energy and amplitude for coressponding applied load. On tensile loading and using the results of the AE analysis, it was found that the event counts, cumulative counts or energy, and amplitude distributions useful for the prediction of damage failure.

• 한국습지학회지
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• 제5권1호
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• pp.41-52
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• 2003

The flood damage reduction studies have been performed by the channel improvement plan and the levee has mainly constructed with the freeboard concept. However, the freeboard concept might be an inappropriate choice as a safety factor of the levee because many uncertainties are involved in the procedure of the channel improvement plan studies. So, we considered the uncertainties In the discharge-probability, stage-discharge, and stage-damage functions and estimate the expected annual damage. The Monte Carlo technique for uncertainty analysis is used. As our results, the expected annual damage with uncertainty shows the larger value than without uncertainty. Since the expected annual damage with uncertainty already considers the safety factor it is the proper result. However, the expected annual damage without uncertainty does not consider the safety factor yet. Thus, if the expected annual damage without uncertainty considers the freeboard concept, it could be compared with the expected annual damage with uncertainty for the evaluation of the overestimation or underestimation of the levee construction.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 1995년도 봄 학술발표회 논문집
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• pp.136-143
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• 1995

The problem of the structural identification becomes important, particularly with relation to the rapid increase of the number of the damaged or deteriorated structures, such as highway bridges, buildings, and industrial facilities. This paper summarizes the recent studies related to those problems by the present authors. The system identfication methods are generally classified as the time domain and the frequency domain methods. As time doamin methods, the sequential algorithms such as the extended Kalman filter and the sequential prediction error method are studied. Several techniques for improving the convergences are incorporated. As frequency domain methods, a new frequency response function estimator is introduced. For damage estimation of existing structures, the modal perturbation and the sensitivity matrix methods are studied. From the example analysis, it has been found that the combined utilization of the measurement data for the static response and the dynamic (modal) properties are very effictive for the damage estimation.

• 한국콘텐츠학회논문지
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• 제18권1호
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• pp.154-163
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• 2018

우리나라뿐만 아니라 전 지구적으로 호우발생 빈도의 증가, 태풍이나 허리케인 세기의 강화 등에 따라 대규모 자연재해의 발생횟수와 피해액은 지속적으로 증가하는 추세이다. 태풍, 홍수, 호우, 강풍, 풍랑, 해일, 조수, 대설, 가뭄, 지진, 황사 등과 같은 자연재해는 발생지점과 규모를 예측하기 어려우며, 전조현상이 명확하게 나타나지 않아 대응에 많은 어려움이 존재한다. 그러나 자연재해의 피해규모를 예측할 수 있다면, 조기대응을 통해 피해를 저감할 수 있을 것이다. 따라서 본 연구에서는 국민안전처에서 발간하는 재해연보('91년~'15년)를 기반으로 서해연안지역의 풍랑피해함수를 개발하였다. 풍랑피해함수는 지역별, 시설별로 구분하여 개발하였으며, NRMSE는 1.94%~26.07%로 분석되었다. 개발된 식을 통해 피해규모를 예측하고, 그에 대한 적절한 대응이 이루어진다면, 피해를 저감할 수 있을 것으로 사료된다.

• 대한기계학회논문집A
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• 제24권2호
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• pp.455-463
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• 2000

In order to develop nondestructive techniques for the quantitative estimation of creep damage a series of crept copper samples were prepared and their ultrasonic velocities were measured. Velocities measured in three directions with respect to the loading axis decreased nonlinearly and their anisotropy increased as a function of creep-induced porosity. A progressive damage model was described to explain the void-velocity relationship, including the anisotropy. The comparison of modeling study showed that the creep voids evolved from sphere toward flat oblate spheroid with its minor axis aligned along the stress direction. This model allowed us to determine the average aspect ratio of voids for a given porosity content. A novel technique, the back propagation neural network (BPNN), was applied for estimating the porosity content due to the creep damage. The measured velocities were used to train the BP classifier, and its accuracy was tested on another set of creep samples containing 0 to 0.7 % void content. When the void aspect ratio was used as input parameter together with the velocity data, the NN algorithm provided much better estimation of void content.