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RISS 인기검색어
- 검색키워드
- 저자 : Lijuan Kong (검색결과 3 건)
- 무료
- 기관 내 무료
- 유료
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Lijuan Kong,Xiaoyu Chen,Yuanbo Du 사단법인 한국계산역학회 2016 Computers and Concrete, An International Journal Vol.17 No.5
In this study, the influence of coarse aggregate size and type on chloride penetration of concrete was investigated, and the grey correlation analysis was applied to find the key influencing factor. Furthermore, the proposed 6-10-1 artificial neural network (ANN) model was constructed, and performed under the MATLAB program. Training, testing and validation of the model stages were performed using 81 experiment data sets. The results show that the aggregate type has less effect on the concrete permeability, compared with the size effect. For concrete with a lower w/b, the coarse aggregate with a larger particle size should be chose, however, for concrete with a higher w/c, the aggregate with a grading of 5-20 mm is preferred, too large or too small aggregates are adverse to concrete chloride diffusivity. A new idea for the optimum selection of aggregate to prepare concrete with a low penetration is provided. Moreover, the ANN model predicted values are compared with actual test results, and the average relative error of prediction is found to be 5.62%. ANN procedure provides guidelines to select appropriate coarse aggregate for required chloride penetration of concrete and will reduce number of trial and error, save cost and time.
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Lijuan Kong,Shuheng Xie,Caihui Wang,Lihuan Wang 한국콘크리트학회 2023 International Journal of Concrete Structures and M Vol.17 No.4
To investigate the application of iron tailings in cement-based materials as fine aggregate and mineral admixture, six iron tailings sands were selected from different places of origin, and the methods of acid and alkali activation were adopted to increase the activity of tailings powder. The strength of mortar was evaluated and the composition and microstructure were analyzed to explore the mechanism. The experimental results show that iron tailings sands had little adverse effect on the mortar strength, and there was a maximum increase of 13.2% in 28-day compressive strength compared with that of river sand mortar. The hardness values of all the iron tailings sand and the interfacial transition zone (ITZ) around them were higher than that of natural river sand, but their Ca/Si ratios in the ITZ was lower, indicating a chemical reaction occurred between the iron tailings and cement paste. Generally, the iron tailings sand with higher SiO2 content and finer particles tend to have higher activity. In addition, the pozzolanic activity of iron tailings powder could be greatly promoted by chemical activation, especially by acid activation. The activity index of cement mortar with unactivated iron tailings powder was only 63% at 28 days, whereas that of acid-activated and compound-activated samples reached up to 93%, and the heights of the maximum heat flow peak of these samples were even higher than that of the control sample without iron tailings powder, and the time to reach the peak was in some advance, moreover their impedance parameters were close to the control sample.
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Lin Chen,Jing Zheng,Dong Kong,Lijuan Yang 한국간호과학회 2020 Asian Nursing Research Vol.14 No.1
Purpose: Enhanced recovery after surgery (ERAS) is an evidence-based perioperative measure to improve outcomes. Although the benefits of ERAS are well proven for other surgeries, little is known about its effect on off-pump coronary artery bypass graft (OPCABG) surgery. Thus, this study aimed to explore the effect of an ERAS protocol in patients who underwent OPCABG surgery. Methods: This quasi-experimental study included 94 participants (traditional care group = 47 vs ERAS group = 47). An ERAS protocol was established by a multidisciplinary team. Knowledge of coronary artery disease, fasting time, water deprivation time, extubation time of the tracheal tube and pericardial and mediastinal drainage tube, off-bed activity participation rate, length of hospital stay, hours of intensive care unit (ICU) stay, expenses in ICU, incidence rates of ICU delirium and postoperative nausea and vomiting, and the 6-Minute Walk Test on postoperative day 7 were recorded and calculated between the groups. Results: Demographics, lifestyle, and disease severity showed no significant difference between the two groups (p > .05). The ERAS group patients had improved understanding of coronary artery disease (t = −3.89, p < .01), shorter fasting time (t = 7.98, p < .01), shorter water deprivation time (t = 9.29, p < .01), increased off-bed activity participation (t = 17.67, p < .01), and the improved 6-Minute Walk Test on postoperative day 7 (t = −3.23, p < .01). Conclusions: The ERAS protocol is safe and effective for patients undergoing OPCABG surgery.
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