Dynamic responses of nuclear power plant structure subjected to earthquake loads should be carefully investigated for safety. Because nuclear power plant structure are usually constructed by material of reinforced concrete, the aging deterioration of R.C. have no small effect on structural behavior of nuclear power plant structure. Therefore, aging deterioration of R.C. nuclear power plant structure should be considered for exact prediction of seismic responses of the structure. In this study, a machine learning model for seismic response prediction of nuclear power plant structure was developed by considering aging deterioration. The OPR-1000 was selected as an example structure for numerical simulation. The OPR-1000 was originally designated as the Korean Standard Nuclear Power Plant (KSNP), and was re-designated as the OPR-1000 in 2005 for foreign sales. 500 artificial ground motions were generated based on site characteristics of Korea. Elastic modulus, damping ratio, poisson’s ratio and density were selected to consider material property variation due to aging deterioration. Six machine learning algorithms such as, Decision Tree (DT), Random Forest (RF), Support Vector Machine (SVM), K-Nearest Neighbor (KNN), Artificial Neural Networks (ANN), eXtreme Gradient Boosting (XGBoost), were used t o construct seispic response prediction model. 13 intensity measures and 4 material properties were used input parameters of the training database. Performance evaluation was performed using metrics like root mean square error, mean square error, mean absolute error, and coefficient of determination. The optimization of hyperparameters was achieved through k-fold cross-validation and grid search techniques. The analysis results show that neural networks present good prediction performance considering aging deterioration.

PURPOSES : This study is performed first to define the aging of road facilities and to analyze the effects of environmental factors on the deterioration of median barriers. METHODS : The aging of road facilities is defined using an analytical hierarchy process (AHP). The first stage is associated with the period, facilities, and maintenance, whereas the second stage is associated with the details. The effects of environmental factors on the deterioration are analyzed by measuring the carbonation depth and compression strength. Two regions, i.e., Gangwon and Busan, are compared separately. Top, middle, and bottom samples are analyzed for both regions. RESULTS : Based on the result of the AHP analysis, weights for period (0.220), function (0.410), and maintenance (0.370) are derived. The average carbonation depths are 11.12 and 9.78 mm for Kangwon and Busan, respectively. The estimated values of compressive strength at Gangwon are 19.7 MPa (Wonju), 24.7 MPa (Samcheok A), and 25.9 MPa (Samcheok B), 20.2 MPa (Haeundae), 23.8 MPa (Yeongdo), and 29.5 MPa (Nam). CONCLUSIONS : The aging of road facilities is associated with subpar functionality and durability. Furthermore, the median barriers constructed in the Gangwon region deteriorated more significantly than those in the Busan region owing to environmental factors. In addition, the bottom samples are more affected by aging than the top samples.

본 연구의 목적은 노화에 따른 작업기억능력의 저하에 영향을 받는 자막인식위치에 대해 탐구하는 것이다. 이를 위해, 본 연구에는 주니어 집단(평균 나이: 26세, 표준편차: 3.06, N=27)과 시니어 집단(평균 나이: 61.69세, 표준편 차: 4.18, N=26)이 참여했으며, 실험 과제로는 실험 참가자들의 작업기억능력을 측정하기 위한 N-back 과제와 자막 인식위치를 측정하기 위한 동영상자막확인 과제가 사용되었다. N-back 과제 수행 결과, 시니어 집단이 주니어 집단 보다 과제에 대한 반응속도가 느리고 정답률이 낮게 나타나, 시니어 집단은 주니어 집단에 비해 작업기억능력의 저하가 나타났다는 것을 의미했다. 또한, 동영상자막확인 과제 수행 결과, 노화에 따른 작업기억능력의 저하에 부정적인 영향을 받는 자막위치는 화면의 ‘좌측-아래’이고 긍정적인 영향을 받는 자막위치는 화면의 ‘좌측-가운데’으로 나타났다. 나머지 화면 위치에서는 노화에 따른 작업기억능력의 저하에 영향을 받지 않았다. 결과적으로 본 연구 결과를 통해서 연령의 증가에 따른 작업기억능력의 저하에 부정적 혹은 긍정적 영향을 받는 영상 속 자막인식위치에 대해서 살펴볼 수 있었으며, 이는 영상에 자막을 제시해야할 경우 시청자의 연령을 고려하여 자막위치를 선정하면 효율적으로 시청자에게 정보를 제공할 수 있다는 것을 의미했다.

Preimplantation embryonic production in vitro is important in human assisted reproductive technology and animal embryo engineering. Icariin (ICA) is one type of flavonoids and a main component isolated from the stem leaf of Epimedium brevicornum. Flavonoids, which are among the best well-studied natural antioxidants, have been demonstrated to be active in clearing reactive oxygen species (ROS). The purpose of this study was to investigate the effects of ICA treatment during porcine oocyte in vitro aging and their in vitro developmental competency after parthenogenetic activation (PA). Porcine oocytes were matured in vitro for 44 h (control) and for an additional 24 h in the presence of 0, 5 μM ICA (aging, ICA-5), respectively. This study investigated the effects of ICA on nuclear maturation, ROS level, apoptosis index, and the developmental capacity of aged porcine oocytes. Oocyte survival was not different in aging group compared to control or ICA-5 group. The increased ROS level during in vitro aging was prevented in ICA-5 group, while GSH level was not decreased. The decrease of normal spindle formation during in vitro aging was prevented in ICA-5 group. After PA, although the cleavage rate was not different among treatment groups, the blastocyst formation was significantly higher in control and ICA-5 group than in aging group. However, there was significantly difference in the apoptotic index of the ICA-5 group, while it was no difference in the total cell number of the ICA-5 group. (p<0.05). Therefore, this result demonstrated that the ICA is an effective agent to prevent the deterioration during in vitro aging of porcine oocytes.

해상송전철탑 구조물에 있어서 구조 및 재료 손상에 대해 주기적으로 안전점검을 실시하고, 그 결과를 이용한 수명관리(life management)의 시행은 적극 추천되는 일이다. 본 연구에서는 영흥도 시화호 내에 있는 총 6개의 해상송전철탑에 대해서 강재부재에 대해 3가지, 콘크리트 기초에 대해 5가지, 해수 중 강관파일 및 해수 자체에 대해 4가지 형태의 열화점검을 각각 수행하였다. 강재에 대한 점검 항목들은 외관조사, 부재두께, 도막상태 등에 대한 것이고, 콘크리트 기초에 있어서는 균열형상, 압축강도, 중성화깊이, 염화물 함유량 등에 대한 항목, 그리고 해중 강관파일에 있어서의 전위 및 양극조사에 따른 부식정도, 동영상 촬영 및 해수의 수질환경성 평가 등에 대한 항목이다. 이와 같은 정기적 열화점검은 연속 3년 동안 매년 10월경에 동일위치에 대해 평가하였다. 결과적으로 본 연구에서는 이러한 자료를 체계적으로 활용함으로써 해상송전철탑 안전성 유지관리에 유익하게 적용될 수 있는 새로운 열화지표를 개발하였다.