• Journal of the Earthquake Engineering Society of Korea
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• v.13 no.5
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• pp.41-50
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• 2009

Following an earthquake, the major concerns for damaged buildings are their safety/risk in the event of aftershocks, and thus a quantitative damage assessment must be performed in order to evaluate their residual seismic capacity and to identify necessary actions for the damaged buildings. Post-event damage evaluation is therefore as essential for the quick recovery of a damaged community as pre-event seismic evaluation and strengthening of vulnerable buildings. The objective of this study is to develop a post-earthquake seismic evaluation method for RC frames with URM infill wall for typical school buildings. For this purpose, full-scale, one-bay, single-story specimens having different axial loads in columns are tested under cyclic loadings. During the tests, residual crack widths, which can also be found in damaged buildings, are measured in order to estimate the residual seismic capacity from the observed damage. In this paper, the relationship between the measured residual crack width and the residual seismic capacity is discussed analytically and experimentally, and reduction factors are proposed to estimate the residual seismic capacity based on the observed damage level.

• Proceedings of the Korea Information Processing Society Conference
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• 2020.11a
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• pp.978-981
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• 2020

제품이나 부품의 잔존 수명을 정확하게 예측할 수 있다면 고장이나 중단으로 인한 손실을 방지하는 것이 가능해질 것이다. 제품의 잔존 수명은 시계열 데이터 분석을 통해 예측될 수 있으며, 최근에는 딥러닝을 이용한 잔존 수명 예측 연구가 활발하게 진행되고 있다. 본 연구에서 우리는 컴퓨터 기반 시스템의 주요 고장 요소가 되고 있는 하드디스크의 잔존 수명을 예측하는 문제에 1D CNN-LSTM 을 이용한 모델을 적용하고, RMSE 와 R-Square 값을 이용해 적용한 모델의 성능을 평가하였다.

• Journal of Korean Society of Steel Construction
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• v.22 no.5
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• pp.399-409
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• 2010

Steel structures are threatened to reduce load-carrying capacity as the cross section is decreased by corrosion. However, there has been no method in definitely evaluating residual load-carrying capacity and the effect of corrosion to the load-carrying capacity of steel. This study evaluated tensile residual load-carrying capacity of corroded steel plates by using tensile tests of specimens, which were selected from the web of temporary structure's main beam. After the surface shapes were measured and tensile tests were examined, the rust of 21 corroded specimens was, first of all, removed using a chemical method. From the tensile test result, which of reference specimens that was picked off at the flange of the same main 13-mm-thick beam and corroded specimens were based, surface geometry and correlation with the reduction of corroded thickness and strain, yield strength or tensile strength was established as constant numbers. Effective thickness of corroded steel with irregular cross sections could be calculated using average residual thickness and standard deviation. The irregular cross sections could be the evaluated tensile strength that is equalized to non-corroded uniform steel's regardless of corrosion. Also, reasonable measuring intervals of residual thickness could be proposed by using this result to apply for executive work.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.1
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• pp.125-132
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• 2010

In the recent construction industry, an external strengthening method using fiber reinforced polymers has been widely used. Since reinforced concrete structures strengthened with fiber reinforced polymers are always under sustained loads, influence of creep and shrinkage on the structures is inevitable. Due to the creep and shrinkage, behaviors of the structures, such as deflection, deformation, recovery capability, strength and so on are also under the influence of creep and shrinkage. Thus, in order to estimate efficacy, creep recovery and residual strength of FRP strengthened RC beams, long-term flexural experiments and static flexural experiments were carried out. As the result of the experiments, FRP strengthened RC beams were very effective in terms of deflection control. Furthermore, the strengthened beams had higher immediate deformation recovery than immediate deformation. Through the static flexural experiments, it was shown that the CFRP strengthened beam had high residual strength. It seems that the sustained loads did not affect bond and residual strength of the beams.

• Journal of the Korea Concrete Institute
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• v.26 no.5
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• pp.643-650
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• 2014

Generally, the reinforced concrete slab has great fire resistance performance because concrete has excellent thermal material properties under fire. But, in the case of hollow slab, it will be expected that hollow slabs have different temperature distribution and fire endurance performance compare to reinforced concrete slab. Because hollow slab has internal void space that occurs decreasing regenerative effect of concrete and formation of internal air layer. Evaluation method for fire resistance performance of hollow slabs was proposed using $wickstr{\ddot{o}}m^{\prime}s$ method. For the casual use of evaluation, simplified method was proposed which was limited to solid slab and donut type hollow slab which was developed by authors of this research paper. Also, verification on proposed method was performed by comparing results of fire experiment for hollow slab and evaluation results. Proposed method of the results of this study was possible to predict the residual strength and temperature distribution of slabs under fire.

• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.941-944
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• 2008

This study is aimed to investigate the residual strength of fire damaged high-performance concrete flexural and compressive members. The compressive strength of specimens is 55MPa and the main parameter for comparison is the exposure time to fire. In case of beams, the cover thickness made the differences in spalled section area, residual strength and serviceability. The exposure time to fire did not affect on the spalled section area in case of compressive members without loading. However, the residual strength and stiffness was reduced by the time exposed to fire. This study can be used to estimate the performance of fire damaged high-strength concrete structural members for reusing and to give the information for repairing and strengthening.

• The Journal of the Korea institute of electronic communication sciences
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• v.18 no.6
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• pp.1151-1156
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• 2023

In this paper, we propose a deep learning model that utilizes charge/discharge data from initial lithium-ion batteries to predict the remaining useful life of lithium-ion batteries. We build the DMP using the PNP model. To demonstrate the performance of DMP, we organize DML using the LSTM model and compare the remaining useful life prediction performance of lithium-ion batteries between DMP and DML. We utilize the RMSE and RMSPE error measurement methods to evaluate the performance of DMP and DML models using test data. The results reveal that the RMSE difference between DMP and DML is 144.62 [Cycle], and the RMSPE difference is 3.37 [%]. These results indicate that the DMP model has a lower error rate than DML. Based on the results of our analysis, we have showcased the superior performance of DMP over DML. This demonstrates that in the field of lithium-ion batteries, the PNP model outperforms the LSTM model.

• Proceedings of the KIPE Conference
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• 2019.07a
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• pp.195-197
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• 2019

자동차용 배터리는 초기 용량의 80% 이하가 되면 교체하게 되며, 근간 폐배터리의 수가 폭발적으로 증가할 것으로 예측되고 있다. 폐배터리의 폐기로 인한 환경 파괴를 방지하고 자원을 재활용하기 위해서 자동차에서 나오는 폐배터리를 에너지저장장치(ESS)로 재사용 하는 것에 대한 관심이 높아지고 있다. 폐배터리를 ESS로 재구성하기 위해서는 폐배터리 모듈의 그레이딩을 통해 비슷한 성능의 모듈끼리 모아서 구성하는 것이 매우 중요하다. 배터리 모듈 간의 불균형은 전체 시스템의 성능을 저하시키며, 따라서 비슷한 성능과 잔존 수명을 가진 모듈을 골라내는 일은 폐배터리의 재사용에 있어서 첫 번째 선결 과제가 된다. 본 연구에서는 폐배터리의 상태 및 잔존수명평가를 위해 배터리 모듈의 임피던스 스펙트럼을 측정할 수 있는 장비를 개발하였다. 폐배터리 모듈에 AC 섭동을 인가하고 이를 측정하여 임피던스 스펙트럼을 계산할 수 있는 하드웨어와 소프트웨어를 개발하였다. 개발 장비는 60V이하의 폐배터리 모듈의 임피던스 스펙트럼을 0.1Hz에서 1kHz까지 측정 가능하며, 측정 결과를 바탕으로 커브 피팅을 통해 등가회로의 파라미터도 계산할 수 있다. SM3에서 얻어진 폐배터리 모듈을 이용하여 측정한 임피던스 스펙트럼을 상용장비인 BIM2로 측정한 결과를 비교하였고, Reduced Chi-Square를 이용한 분석결과 두 데이터가 거의 일치함을 알 수 있었다.

• Journal of Korea Water Resources Association
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• v.50 no.10
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• pp.673-679
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• 2017

In this paper a method for estimating the 'service life' and 'residual life' of a water pipe based on the Water Pipe Network Performance Evaluation(WPNPE) results of Water Supply Technical Diagnosis was developed for efficient maintenance of water pipes. The residual life of a pipe was defined as the difference between the service life and elapsed time since installation. The service life was defined as the time when a pipe reaches the reference score for determining deteriorated pipes that was used in the WPNPE. The pipe evaluation criteria and deterioration scores used in the WPNPE for the case study area were considered as independent variables in the multiple regression model for estimating the service life and residual life of the pipes in the area. To estimate the service life for the pipes the reference scores for determining deteriorated pipes were used as the values of the variables that represent the deterioration scores in the constructed regression models. Subsequently, the statistics of the service life and residual life of the pipes in the case study area were presented and analyzed in comparison with the service life defined by the Local Public Enterprizes Act.

• Proceedings of the KIEE Conference
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• 2011.07a
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• pp.547-548
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• 2011

본 논문에서는 한국전력공사에서 장기열화 시험을 수행한 154kV 고분자애자의 성능평가를 수행하고 그 결과를 1999년부터 2008년까지 한국전력공사154kV 송전선로에 시범 설치한 고분자애자의 주간코로나, 열화상 측정을 시행하고 제조회사/규격별 각 24련을 발취하여 총 168련에 대하여 한전 표준구매 규격에 따른 각종 시험을 수행하고 현 성능상태를 검증하였으며 이를 토대로 잔존 수명을 예측하고자 하였다. 대부분의 애자가 양호한 성능을 보이고 있으나 일부 애자에서는 부적합 결과를 보였으며 수명의 경우, 초기 품질계수 정보 부족 및 중간열화 상태의 데이터 부족으로 정확한 잔존수명 예측 데이터를 얻기에는 부족했으며 추가적인 가속열화시험 등의 데이터를 확보해야 할 것으로 사료된다.