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폐섬유를 활용한 바탕콘크리트의 균열 및 복합열화 저감에 관한 연구
추용희 ( Chu¸ Yong-hui ),강예진 ( Kang¸ Ye-jin ),이동운 ( Lee¸ Dong-oun ),김대건 ( Kim¸ Dae-geon ) 한국건축시공학회 2021 한국건축시공학회 학술발표대회 논문집 Vol.21 No.2
Recently, 67% of defect and tenant lawsuits were identified as leaks due to cracks. In particular, when the final finish of the roof of a building is designed with base concrete, complex deterioration occurs due to the harsh environment such as shrinkage and expansion due to external temperature changes, freezing and thawing, and the use of calcium chloride due to snow accumulation. Therefore, it is intended to secure long-term durability by reducing cracks in the base concrete by using waste fibers, which are industrial by-products.
Yonghui Zhao(Yonghui Zhao),Jia Zhao(Jia Zhao),Xiaolei Wang(Xiaolei Wang) 한국무역연구원 2022 무역연구 Vol.18 No.6
Purpose – The growth of mobile delivery apps is expanding further due to the increase in nonface- to-face consumption due to social distancing in the COVID-19 situation. It is essential to understand what factors are causing this mobile delivery app market to grow significantly. Design/Methodology/Approach – To achieve the purpose of the study, independent variables were selected by searching for prior literature on UTAUT, and a questionnaire was designed according to the situation in Korea. The survey was conducted through Google Online, and statistical analysis of the research model was conducted using SPSS 25.0. Findings – According to the results of this study, the factors that significantly influence the intention to use mobile delivery apps were Performance Expectancy (PE), Effort Expectancy (EE), Social Influence (SI), and Facilitating Conditions (FC). In addition, the result indicated that Behavioral Intention (BI) had a statistically significant effect on Use Behavior (UB). Research Implications – This study will predict the user behavior of mobile delivery apps by dealing with the technical attributes of mobile delivery apps and the influencing factors that consumers recognize. In addition, as a mobile delivery app company, it is expected to play a role in establishing the marketing direction of mobile delivery apps.
Yonghui Wang,Ximei Zhai 한국강구조학회 2020 International Journal of Steel Structures Vol.20 No.1
This paper presents numerical works and multi-objective optimization of the energy absorbing connectors which was employed to dissipate blast/impact energy through curved plates and aluminum foam. Finite element models of the energy absorbing connectors under dynamic crushing load were established and validated with the impact loading tests. Then, the parametric studies were conducted to reveal the infl uences of crushing velocity, angle θ , curved plate thickness as well as length and height of aluminum foam on the energy absorbing characteristics. Increasing crushing velocity was shown to improve the absorbed energy of the connector owing to the strain rate enhancement and change of deformation mode. In addition, the absorbed energy could also be increased via increasing curve plate thickness, length and height of aluminum foam as well as decreasing angle θ . The multi-objective optimization was conducted by employing the non-dominated sorting genetic algorithm II. It was noted that the specifi c energy absorption and peak crushing force were confl icting with each other.
Economic Design of Automated Spiral Parking System
Yonghui Oh,Yun Chul Sung,Hark Hwang 대한산업공학회 2008 Industrial Engineeering & Management Systems Vol.7 No.2
Automated parking systems, which automatically park and retrieve vehicles, have been steadily replacing conventional parking systems. The spiral parking system is a type of automated parking systems that has cylindrical parking tower. We develop an economic design model of spiral parking system based on a recursive optimization and simulation procedure in which the dynamic nature of the parking system can be integrated into the mathematical programming model. The optimal values of design parameters are found that gives the minimum total cost while complying with the desired performance of the system.
A dynamic finite element method for the estimation of cable tension
Yonghui Huang,Quan Gan,Shiping Huang,Ronghui Wang 국제구조공학회 2018 Structural Engineering and Mechanics, An Int'l Jou Vol.68 No.4
Cable supported structures have been widely used in civil engineering. Cable tension estimation has great importance in cable supported structures’ analysis, ranging from design to construction and from inspection to maintenance. Even though the Bernoulli-Euler beam element is commonly used in the traditional finite element method for calculation of frequency and cable tension estimation, many elements must be meshed to achieve accurate results, leading to expensive computation. To improve the accuracy and efficiency, a dynamic finite element method for estimation of cable tension is proposed. In this method, following the dynamic stiffness matrix method, frequency-dependent shape functions are adopted to derive the stiffness and mass matrices of an exact beam element that can be used for natural frequency calculation and cable tension estimation. An iterative algorithm is used for the exact beam element to determine both the exact natural frequencies and the cable tension. Illustrative examples show that, compared with the cable tension estimation method using the conventional beam element, the proposed method has a distinct advantage regarding the accuracy and the computational time.
Yonghui Zhou,Hu Sun,Anhai Li,Minghang Lv,Chaoyi Xue,Jun Zhao 대한기계학회 2019 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.33 No.7
The Johnson-Cook (JC) constitutive model was utilized to simulate the processing of Al-Si piston alloy ZL109 to obtain the optimal finishing parameters in polycrystalline diamond (PCD) tool, and studied the machining quality of ordinary-turning under the optimized cutting parameters. PCD is brittle, so it is difficult to manufacture orthogonal blades and is easy to break and high cost. We have adopted ordinary-turning quality to verify simulation results. Effect of cutting parameters on residual stress, cutting force and temperature was investigated through simulation, meanwhile, effect of cutting parameters on surface roughness and residual stress was analyzed by experiments. It indicates the verification method is practicable, and residual stress, cutting force and temperature are the smallest in simulation, and the experimental values of surface roughness and residual stress are also the smallest under the optimal cutting parameters, which can guide the cutting parameters selection to obtain higher machining quality.
Yonghui Li,Mingkai Wang,Xingxing Cao,Zhongfeng Geng 한국화학공학회 2020 Korean Journal of Chemical Engineering Vol.37 No.5
The synthesis of vinyl acetate (VAc) from ethylene is a strongly exothermic reaction that might easily cause catalyst deactivation and reduce selectivity of VAc. Research at the bed scale helps to improve the conversion of C2H4 and the selectivity of VAc. In this study, the discrete element method (DEM) was used to construct a fixed-bed structure model via simulating the filling process of catalyst particles in the reactor. The inlet section of a reaction tube was studied, and its length was 10 cm. The temperature distribution, and the effects of particles size, inlet velocity, inlet temperature and the feed ratio of C2H4 to O2 on the reaction process were studied. Simulated results show that the bed temperature gradually increased from the wall to the center, and the temperature gradient gradually decreased along the radial direction. The maximum temperature was 438.68 K and the temperature difference from the inlet temperature was 5.54 K. Comparing the composite particle packed bed with the single particle size packed bed, the composite packed bed has higher vinyl acetate selectivity. Increasing inlet velocity from 1.5m/s to 3.5m/s, the selectivity of vinyl acetate increased from 91.71% to 92.60%. Adding an inert gas to the feed gas can increase the oxygen concentration and reduce the explosion interval of C2H4, the conversion of C2H4 and the selectivity of vinyl acetate increased.