• 한국응용곤충학회지
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• 제34권1호
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• pp.33-39
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• 1995

본문은 가지의 포전시험자료에 근거하여 점박이응애붙이(Tetranichus cinabaruinus(Boisduval))의 밀도와 피해엄중도간의 관계를 검토하였는데 그 결과 응애밀도와 피해엄중도간의 농약을 살포하기전 혹은 응애가 확산하기 전에는 정상관성(r=${0.865}^{\ast}{\ast}$)을 나타냈으나 통상적인 수량적 관계는 나타내지 않았다. 계통적조사에 근거하여 실제피해엄중도(DI) 증가율 model과 실측피해엄중도 model을 작성한 후 그 두 model로 실제피해엄중도 측정 model을 구성하였다. 피해정도를 잘 반영할 수 있는 누적피해일(cumulative damage days, CDD) 개념을 제출하고 그 수학적 model을 세웠다. 누적피해일은 실제피해엄중도곡선아래의 면적으로서 적분으로 표할 수 있는데 그속에 피해의 점차적이며 누적적인 기본 과정이 뒷받침 되어 있지 않다. 여러 가지 피해정도 표기법을 서로 서로 비교한 결과 CDD가 가장 합리적이었고 또한 동일한 생태조건(동지)하에서는 CDD와 DI가 일정한 등가성이 있었다.

• 대한토목학회논문집
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• 제6권4호
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• pp.79-88
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• 1986

본(本) 논문(論文)에서는 크기가 변(變)하는 변동진폭(變動振幅)의 반복하중이 콘크리트구조물(構造物)에 작용(作用)할 경우 피로파괴를 예측할 수 있는 비선형누적손상이론(非線型累積損傷理論)을 제안(提案)하였다. 이를 위하여 콘크리트보에 대한 피로실험이 수행되었으며, 피로하중은 2단계 및 3단계로 크기가 증가하는 경우와 감소하는 경우가 모두 고려되었다. 본(本) 연구(硏究)의 실험결과(實驗結果) 변동진폭(變動振幅)의 반복하중을 받는 콘크리트에 발생하는 누적손상은 피로하중의 크기와 피로하중의 작용순서에 따라 많은 영향을 받는 것으로 나타났으며, 따라서 Palmgren-Miner의 선형손상이론이 콘크리트의 경우 적합하지 않음을 보여주고 있다. 피로하중이 점진적으로 증가하는 경우 Miner의 손상합(損傷合)은 1 보다 크며, 피로하중이 점진적으로 감소하는 경우 이 손상합은 1 보다 작은 것으로 나타났다. 본(本) 논문(論文)에서 제안(提案)된 비선형(非線型) 누적손상이론(累積損傷理論)을 피로하중의 크기와 작용순서의 영향을 고려할 수 있는 보다 진보(進步)된 손상이론으로서, 콘크리트 구조용의 피로해석 및 설계에 있어 하나의 토대가 될 것으로 사료된다.

• 한국시뮬레이션학회논문지
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• 제29권2호
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• pp.119-127
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• 2020

본 연구에서는 해석적 방법을 이용하여 연속폭발 하중을 받는 구조물의 거동을 분석하였다. 구조물은 양단이 고정된 축소형 일방향 철근콘크리트 슬래브를 사용하였으며, 유한요소 해석을 위해서 상용 소프트웨어인 LS-DYNA를 사용하였다. 누적피해 평가를 위한 해석을 수행하기에 앞서, 해석 모델의 검증을 위해 일방향 철근콘크리트 슬래브의 단일폭발 실험을 수행하였다. 누적피해 해석에서는 이상적인 연속폭발 하중이 구조물에 적용되고, 최대변위를 기준으로 누적 피해평가를 수행하였다. 해석 결과로부터, 연속폭발 하중을 받는 철근콘크리트 슬래브의 최대 누적변위는 위험한 피해 한계까지 일정하게 증가하는 경향을 보였다.

• 한국신재생에너지학회:학술대회논문집
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• 한국신재생에너지학회 2005년도 제17회 워크샵 및 추계학술대회
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• pp.693-697
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• 2005

This study was performed to develop accelerated life test method of the wind-turbine gearbox using accumulated damage theory that used to model the fatigue of parts that receive variable load. The accumulated damage theory was introduced, and the estimation of life and calculation of accelerated life test time was illustrated. As the actual application example, accelerated life test method of the gearbox was described. Life distribution of the wind-turbine gearbox was supposed to follow Weibull distribution and life test time was calculated under the conditions of average life (MTBF) 140,600 hours and 99% reliability for one test sample According to the accumulated damage theory, because test time can shorten in case increase test load, test time could be reduced by 1.2 years when we put the load 1.2 times of rated load than 0.93 times of rated load that is equivalent load calculated by load spectrum of the wind turbine. This time, acceleration coefficient was 21.3. This accelerated test method was used to develop accelerated test method of gear reducer, gear and bearing as well as the industrial gearbox and it is considered to be applied comprehensively to mechanical parts the fatigue of which is happened by load or pressure etc.

• Earthquakes and Structures
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• 제7권2호
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• pp.179-199
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• 2014

The steel tube-reinforced concrete (ST-RC) composite column is a novel type of composite column, consisting of a steel tube embedded in reinforced concrete. The objective of this paper is to investigate the effect of cumulative damage on the seismic behavior of ST-RC columns through experimental testing. Six large-scale ST-RC column specimens were subjected to high axial forces and cyclic lateral loading. The specimens included two groups, where Group I had a higher amount of transverse reinforcement than Group II. The test results indicate that all specimens failed in a flexural mode, characterized by buckling and yielding of longitudinal rebars, failure of transverse rebars, compressive crushing of concrete, and steel tube buckling at the base of the columns. The number of loading cycles was found to have minimal effect on the strength capacity of the specimens. The number of loading cycles had limited effect on the deformation capacity for the Group I specimens, while an obvious effect on the deformation capacity for the Group II specimens was observed. The Group I specimen showed significantly larger deformation and energy dissipation capacities than the corresponding Group II specimen, for the case where the lateral cyclic loads were repeated ten cycles at each drift level. The ultimate displacement of the Group I specimen was 25% larger than that of the Group II counterpart, and the cumulative energy dissipated by the former was 2.8 times that of the latter. Based on the test results, recommendations are made for the amount of transverse reinforcement required in seismic design of ST-RC columns for ensuring adequate deformation capacity.

• 한국해양공학회지
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• 제5권2호
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• pp.225-225
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• 1991

• 한국항공우주학회지
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• 제49권1호
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• pp.1-12
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• 2021

본 논문은 복합재 패널에서 압전 작동기를 사용하여 탄성파를 생성하고, 손상에서의 반사된 신호를 압전 감지기에서 탐지하여 손상위치를 추정할 수 있는 알고리즘을 개발하였다. 손상이 없는 신호와 손상이 있는 신호를 비교하여 손상신호를 추정하는 진단적 접근방법을 사용하였다. 신호 상관관계를 이용하여 탄성파의 군속도를 계산하고 압전기 위치정보를 이용하여 손상정보를 추출하였다. 하지만 탄성파의 비선형 특성으로 인해, 손상정보는 다양한 신호의 조합으로 구성되기 때문에, 손상위치를 명확히 구별하기 어렵다. 이에 본 논문에서는 손상에서 반사된 신호정보를 신호 도달거리의 면적으로 변환해서 손상의 중심위치를 찾는 누적함수 특성벡터 알고리즘(CSFV, cumulative summation feature vector)을 새롭게 제안하고, 특성벡터를 손상지수와의 곱으로 표현하는 가시화 기법을 적용하였다. 또한 복합재 패널에서 실험검증을 수행하고, 기존의 알고리즘과의 비교를 통해 제안된 알고리즘이 정확도 높게 손상위치를 검출할 수 있음을 보였다.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2008년도 춘계 학술발표회 초청강연 및 논문집
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• pp.575-586
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• 2008

The main objective of this paper is to develop an improved model for the analysis of liquefaction potential and to predict excess pore pressure (EPP) using the proposed model that can simulate behavior of saturated sand under earthquake loading conditions. The damage concept is adopted for the development of the proposed model. For the development of the model, a general formulation based on experimental results and damage potential using cumulative absolute velocity (CAV) is proposed for a more realistic description of dynamic responses of saturated sand. Undrained dynamic triaxial tests are conducted using earthquake loading conditions. Based on test results, the NCER-NCW function in terms of $w_d$ and CAV is developed. Procedure for the evaluation of EPP and determination of model parameters for the proposed model is presented as well. For the determination of initial liquefaction, the minimum curvature method using the NCS-NCW curve is proposed. It is observed that predicted initial liquefaction using the proposed method agrees well with measured initial liquefaction. From results of additional undrained dynamic triaxial tests, it is seen that predicted EPP generation using the proposed model agrees well with measured results for earthquake loading cases.

• 한국위험물학회지
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• 제3권1호
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• pp.28-36
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• 2015

In early 2011, the Fukushima nuclear power plant had greater damage due to earthquake in Japan, and the awareness of safety has increased. In particular, special response systems should be required to handle disaster situations in plant sites which are likely to occur for large disasters. In this study, a program is designed to set up optimum escape routes, by a smart phone application, when a disaster situation occurs. This program could get information of the cumulative damage from sensors and display the escape route of the smallest damage in real-time on the screen. Utilizing our application in real-time evacuation has advantage in reducing cumulative damage. The optimal evacuation route, focusing on horizontal path, is calculated based on getting the data of fire, detected radioactivity and hazardous gas. Thus, using our application provides information of optimal evacuation to people who even can not hear sensor alarms or do not know geography, without requiring additional costs except fixed sensors or server network deployment cost. As a result, being informed of real-time escape route, the user could behave rapidly with suitable response to individual situation resulting in improved evacuation than simply reacting to existing warning alarms.

• 한국환경복원기술학회지
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• 제9권6호
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• pp.107-116
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• 2006

Recently, it has been important not only to evaluate environmental effects but also to assess cumulative and comprehensive effects by the development projects. This paper concentrates on temporal and spatial cumulative impacts on Suji district in Yongin, Gyunggi-do. This paper adopted two methods to assess the cumulative impacts. First, it assesses the temporal change of forest patch size and land cover according to the patch size. Second, it compares housing development zones with the neighborhood. The result of the research appears that the damage is very serious, especially in small forest. The Forest area is changed to farm land, most of them become to built-up area later. In addition, it is assessed that the secondary housing development projects did more harm than the initial one. By assessing the cumulative impacts on Suji district, this research suggests to minimize two kinds of solutions : comprehensive environmental assessments in regional unit and regulation on total forest quantity.