Chloride diffusivity of concrete: probabilistic characteristics at meso-scale

Zichao Pan,Xin Ruan,Airong Chen 사단법인 한국계산역학회 2014 Computers and Concrete, An International Journal Vol.13 No.2

This paper mainly discusses the influence of the aggregate properties including grading, shape, content and distribution on the chloride diffusion coefficient, as well as the initiation time of steel corrosion from a probabilistic point of view. Towards this goal, a simulation method of random aggregate structure (RAS) based on elliptical particles and a procedure of finite element analysis (FEA) at meso-scale are firstly developed to perform the analysis. Next, the chloride diffusion coefficient ratio between concrete and cement paste ??app??cp is chosen as the index to represent the effect of aggregates on the chloride diffusion process. Identification of the random distribution of this index demonstrates that it can be viewed as actually having a normal distribution. After that, the effect of aggregates on ??app??cp is comprehensively studied, showing that the appropriate properties of aggregates should be decided by both of the average and the deviation of ??app??cp . Finally, a case study is conducted to demonstrate the application of this mesoscopic method in predicting the initiation time of steel corrosion in reinforced concrete (RC) structures. The mesoscopic probabilistic method developed in this paper can not only provide more reliable evidences on the proper grading and shape of aggregates, but also play an important role in the probability-based design method.

A 2-D numerical research on spatial variability of concrete carbonation depth at meso-scale

Zichao Pan,Xin Ruan,Airong Chen 사단법인 한국계산역학회 2015 Computers and Concrete, An International Journal Vol.15 No.2

This paper discusses the spatial variability of the carbonation depth caused by the mesoscopic structure of the concrete and the influence of the spatial variability on the thickness of the concrete cover. To conduct the research, a method to generate the random aggregate structure (RAS) based on polygonal particles and a simplified numerical model of the concrete carbonation at meso-scale are firstly developed. Based on the method and model, the effect of the aggregate properties including shape, content and gradation on the spatial variability of the carbonation depth is comprehensively studied. The results show that a larger degree of the spatial variability will be obtained by using (1) the aggregates with a larger aspect ratio; (2) a larger aggregate content; (3) the gradation which has more large particles. The proper sample size and model size used in the analysis are also studied. Finally, a case study is conducted to demonstrate the influence of the spatial variability of the carbonation depth on the proper thickness of the concrete cover. The research in this paper not only provides suggestions on how to decrease the spatial variability, but also proposes the method to consider the effect of the spatial variability in designing the thickness of the concrete cover.

A study on ITZ percolation threshold in mortar with ellipsoidal aggregate particles

Zichao Pan,Dalei Wang,Rujin Ma,Airong Chen 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.22 No.6

The percolation of interfacial transition zone (ITZ) in cementitious materials is of great importance to the transport properties and durability issues. This paper presents numerical simulation research on the ITZ percolation threshold of mortar specimens at meso-scale. To simulate the meso-scale model of mortar as realistically as possible, the aggregates are simplified as ellipsoids with arbitrary orientations. Major and minor aspect ratios are defined to represent the global shape characteristics of aggregates. Some algorithms such as the burning algorithm, Dijkstra’s algorithm and Connected-Component Labeling (CCL) algorithm are adopted for identification of connected ITZ clusters and percolation detection. The effects of gradation and aspect ratios of aggregates on ITZ percolation threshold are quantitatively studied. The results show that (1) the ITZ percolation threshold is mainly affected by the specific surface area (SSA) of aggregates and shows a global decreasing tendency with an increasing SSA; (2) elongated ellipsoidal particles can effectively bridge isolated ITZ clusters and thus lower the ITZ percolation threshold; (3) as ITZ volume fraction increases, the bridging effect of elongated particles will be less significant, and has only a minor effect on ITZ percolation threshold; (4) it is the ITZ connectivity that is essentially responsible for ITZ percolation threshold, while other factors such as SSA and ITZ volume fraction are only the superficial reasons.

중국호텔 종사원이 지각하는 심리적 자본이 조직시민행동과 직무성과에 미치는 영향

진자초 ( Zichao Chen ),김영현 ( Younghyun Kim ) 관광경영학회 2021 관광경영연구 Vol.101 No.-

This research has aimed to verify the relationship among psychological capital, organizational citizenship behavior and job performance. The results of empirical analysis are as follows: Firstly, according to the results which verify the effects of psychological capital on organizational citizenship behavior, hope, optimism and resilience, the sub-factors of psychological capital, have positive (+) effects on organizational citizenship behavior, while the effects of self-efficacy on organizational citizenship behavior are insignificant. Secondly, according to the results which verify the effects of psychological capital on job performance, self-efficacy and optimism, the sub-factors of psychological capital, have positive (+) effects on job performance, while the effects of hope and resilience on job performance are insignificant. Therefore, that it is necessary for hotel enterprises to introduce human resource management system that can improve the psychological capital of employees is proposed. For example, as for job performance, it is necessary for internal hotel industry to adopt relatively fair personnel system, which means that it is most important to actively respond to work of employees within the hotels so as to provide confidence when executing work in the future. Systematizing correct incentive for goals is also most important.

중국호텔 종사원이 지각하는 조직시민행동이 직무성과에 미치는 영향에 있어 감성지능의 조절효과

진자초 ( Zichao Chen ),김영현 ( Younghyun Kim ) 관광경영학회 2020 관광경영연구 Vol.98 No.-

In this research takes employees in Chinese hotels as subjects to verify the relationship organizational citizenship behavior and job performance, and moderating effect of emotional intelligence in the effects of organizational citizenship behavior on job performance. The results of empirical analysis are as follows: Firstly, according to the results which verify the effects of organizational citizenship behavior on job performance, organizational citizenship behavior has positive (+) effects on job performance. The reason lies in the fact that employees with higher organizational citizenship behavior devote every effort to their businesses. Therefore, human resource manager within the hotels should strengthen internal marketing and carry out training courses that can inculcate organizational citizenship behavior consciousness into employees. Secondly, according to the results which verify the moderating effect of emotional intelligence in the relationship between organizational citizenship behavior and job performance, only understanding ego emotion and emotion utilization in the emotional intelligence can moderate the relationship between organizational citizenship behavior and job performance, while understanding others’ emotion, emotion moderation and emotion recovery cannot moderate this kind of relationship. Therefore, it is necessary to develop various procedures and carry out training support to understand positive psychological procedures and ego emotion better and utilize emotions positively through culturing positive thinking mode.

Evaluation of light-emitting diode colors and intensities on slaughter performance, meat quality and serum antioxidant capacity in caged broilers

Tan Zichao,Zhou Chuanfeng,Shi Xueping,Wang Lihua,Wang Shubai 아세아·태평양축산학회 2023 Animal Bioscience Vol.36 No.5

Objective: This study was to evaluate the interaction of three different light-emitting diode (LED) light colors (white, green, and blue) and three intensities (5, 10, and 15 lx) on slaughter performance, meat quality and serum antioxidant capacity of broilers raised in three-layer cages. Methods: A total of 648 (8-days-old) male broiler chicks (Cobb-500) were randomly assigned in 3×3 factorially arranged treatments: three light colors (specifically, white, blue, and green) and three light intensities (namely, 5, 10, and 15 lx) for 35 days. Each treatment consisted of 6 replicates of 12 chicks. The test lasted for 35 days. Results: The semi-eviscerated weight percentage (SEWP) in 5 lx white was higher than that in 15 lx (p<0.01). The eviscerated weight percentage (EWP) (p<0.05) and water-loss percentage (WLP) (p<0.01) decreased in 10 lx white light than those in green light. Under blue light, the content of hypoxanthine (Hx) in muscle was lower than that under white and green light (p<0.01). The content of malondialdehyde (MDA) in 15 lx blue light was higher than that in 10 lx green light (p<0.05). Light color had an extremely significant effect on thigh muscle percentage, WLP, Hx, and crude protein content (p<0.01). Light intensity had a significant effect on SEWP (p<0.05), EWP (p<0.05), lightness (L*) value (p<0.05), WLP (p<0.01), and the contents of superoxide dismutase (p<0.05), MDA (p< 0.01), glutathione peroxidase (p<0.01). Conclusion: Using white LED light with 10 lx light intensity can significantly improve the chicken quality of caged Cobb broilers, improve the content of inosine acid in chicken breast and enhance the antioxidant capacity of the body. We suggest that the broiler farm can use 10 lx white LED light source for lighting in 8 to 42 days.

중국 호텔 종사원이 지각하는 감성지능이 직무성과에 미치는 영향에 있어 프렌드십의 조절효과

진자초 ( Zichao Chen ),최우성 ( Woosung Choi ) 관광경영학회 2019 관광경영연구 Vol.88 No.-

The purpose of this study is to examine the effects of perceived emotional intelligence on job performance and the moderating effect of friendship in these relationships among 3 or more star hotel employees in Shanghai and surrounding areas of economic center of China, The results of the study are as follows. In the relationship between emotional intelligence and job performance, the higher the perception of self - emotion, the greater the job performance. And that the understanding of other people 's emotions influenced job performance in a positive (+) direction. In addition, higher perceptions of emotional use showed that job performance also increased. A high perception of emotional control showed that job performance increased. Although emotional recovery does not have a significant effect on job performance, job performance increases with the adjustment effect of supervisor 's friendliness. And it was found that the emotional use affects the job performance. Based on these results, Chinese hotel employees should carry out programs that continuously promote emotional and emotional intelligence, superior friendships and friendships of friends in order to maximize job performance. Specific measures should be presented.

중국인 유학생의 문화지능과 대학생활적응과의 관계에서 사회적 유대감의 매개효과

이수진(Su-Jin Lee),장자초(Zichao Zhang),김유리(Yu-Ri Kim) 중앙대학교 한국교육문제연구소 2016 한국교육문제연구 Vol.34 No.2

본 연구는 한국에 거주하고 있는 중국인 유학생의 문화지능과 대학생활적응의 관계에서 사회적 유대감의 매개효과를 살펴보는데 그 목적이 있다. 연구대상으로는 서울에 있는 4년제 대학에 재학 중인 중국인 유학생 244명을 선정하여 설문 조사를 진행하였고 최종분석에 216명을 포함시켰다. 자료 분석은 SPSS 23.0을 이용하여 중국인 유학생들의 문화지능, 사회적 유대감, 대학생활적응 간의 관계를 살펴보았으며, 중국인 유학생들의 문화지능과 대학생활적응 간의 관계에서 사회적 유대감의 매개효과를 알아보기 위하여 Baron과 Kenny(1986)의 3단계 절차에 따라 회귀분석을 실시하였다. 연구결과 문화지능, 사회적 유대감, 대학생활적응이 모두 유의미한 정적 상관이 있는 것으로 확인되었다. 또한 문화지능은 사회적 유대감을 증가시키며, 사회적 유대감은 문화지능이 대학생활적응에 미치는 영향을 부분매개 하는 것으로 확인되었다. 본 연구 결과는 문화적응 및 대학생활적응에 영향을 주는 개인 내적특성으로서의 문화지능에 대한 이해를 넓힐 수 있었으며, 아울러 대학현장에서 중국인 유학생들의 학교생활적응을 도모하기 위한 실제적인 전략을 구성하는데 필요한 기초자료를 제공하고 있다. 향후연구를 위한 제언과 본 연구의 제한점을 기술하였다. This study examined the mediated effect of social connectedness in explaining the relationship between cultural intelligence and school adjustment among Chinese students in Korea. The questionnaire is composed of social connectedness, cultural intelligence and school adjustment answered by Likert-type scale. The objects of study are 244 Chinese students in universities in Seoul and 216 responses are analyzed by SPSS 23.0. As the results of this study show, it appeared that all variables have static correlations among cultural intelligence, social connectedness and school adjustment. Also, social connectedness played a partial mediator role in explaining the relationship between cultural intelligence and school adjustment. This present study implied the importance of social connectedness to develop intervention programs for successful adjustment in school.

A multiscale numerical simulation approach for chloride diffusion and rebar corrosion with compensation model

Xi Tu,Zhengliang Li,Airong Chen,Zichao Pan 사단법인 한국계산역학회 2018 Computers and Concrete, An International Journal Vol.21 No.4

Refined analysis depicting mass transportation and physicochemical reaction and reasonable computing load with acceptable DOFs are the two major challenges of numerical simulation for concrete durability. Mesoscopic numerical simulation for chloride diffusion considering binder, aggregate and interfacial transition zone is unable to be expended to the full structure due to huge number of DOFs. In this paper, a multiscale approach of combining both mesoscopic model including full-graded aggregate and equivalent macroscopic model was introduced. An equivalent conversion of chloride content at the Interfacial Transition Layer (ITL) connecting both models was considered. Feasibility and relative error were discussed by analytical deduction and numerical simulation. Case study clearly showed that larger analysis model in multiscale model expanded the diffusion space of chloride ion and decreased chloride content in front of rebar. Difference for single-scale simulation and multiscale approach was observed. Finally, this paper addressed some worth-noting conclusions about the chloride distribution and rebar corrosion regarding the configuration of rebar placement, rebar diameter, concrete cover and exposure period.

Genetic architecture of flag leaf length and width in rice (Oryza sativa L.) revealed by association mapping

Jiantao Wu,Yongwen Qi,Guanglong Hu,Jinjie Li,Zichao Li,Hongliang Zhang 한국유전학회 2017 Genes & Genomics Vol.39 No.3

Rice flag leaf is the main photosynthetic organ and plays a key role in grain yield. In this study, 106 loci associated with flag leaf length and width were identified using association mapping in a rice mini core collection. Analyzing the phenotypic effects of each allele represented 156 positive and 167 negative alleles, with a few alleles showing inconsistent effect in different environments. Among the 106 loci, 69 were environment-specific loci, 16 were environmentally stable and 21 were environmentally sensitive. Fifteen associated markers were shared by two traits and were designated as pleiotropic markers. According to the frequency distribution of alleles in different variety types, 343 alleles were categorized into three types based on geographic source and usage in breeding. Among these, 156 were used alleles, 138 were unused and 49 were foreign alleles. The results further our understanding of the genetic mechanisms of flag leaf length and width.