NEW PRODUCT INTRODUCTION VIA SOCIAL MEDIA INFLUENCER

Zhenhao Li,Liping Liang 글로벌지식마케팅경영학회 2023 Global Marketing Conference Vol.2023 No.07

Firms are increasingly using social media influencers to promote their products. We develop a two-period model to investigate a firm’s strategy for introducing a product via an influencer, where there is uncertainty in the influencer-product match. In the second period, the influencer exerts an effort to promote the product to her followers, who can spread the product information to non-followers via word-of-mouth (WOM). In the second period, the firm sells to the non-followers. We show that the firm’s pricing, production, and commission contract decisions depend on the influencer’s incentive-independent excess payoff from the promotion and on the difference between the WOM effect of followers who do or do not make a purchase rather than the WOM effect of each group. As the influencer’s incentive-independent payoff increase, the firm will increase (decrease) commissison rate and commission rate when the followers’ sensitivity to product price is relatively low (high) compared with that to the influencer’s effort. As the marginal WOM benefit of the first-period sales increases, the firm tends to reduce his unit net profit from sales. The influencer with a medium-sized follower base receives the highest commission rate and exerts the largest promotion effort. While the followers of influencers with a medium-sized follower base may pay the highest price. We also show that (i) there exists a threshold for the probability of match, above which the firm faces zero demand in the first period if an influencer-product mismatch occurs; and (ii) the firm may charge followers a lower price than non-followers, even though followers are less sensitive to price than non-followers. Finally, regarding influencer selection, we find that the firm may not be better off employing an influencer with a larger follower base.

CFD Study for Wave Run-up Characteristics Around a Truncated Cylinder with Damper

Zhenhao Song,Bo Woo Nam 한국해양공학회 2023 韓國海洋工學會誌 Vol.37 No.6

Parameter Optimization for the Thickness and Hydraulic Conductivity of Tunnel Lining and Grouting Rings

Zhenhao Xu,Xintong Wang,Shucai Li,Bin Gao,Shaoshuai Shi,Xinji Xu 대한토목학회 2019 KSCE JOURNAL OF CIVIL ENGINEERING Vol.23 No.6

Water inrush is a serious geological hazard in the deep buried tunnel construction in karst areas. Lining and grouting ring are often built to prevent tunnel from water inrush. The estimation of external water pressure and water inflow is of great significance to the structure design of lining and grouting ring. In this paper, the axisymmetric analytic solutions of external water pressure and water inflow were derived for deep karst tunnels under saturated steady-state flow conditions. A simplified formula for the reduction coefficient of external water pressure was established. This paper analyzed the changing rule of water inflow coefficient and the reduction coefficient of external hydraulic pressure on linings, which varies with the parameters of lining and grouting circle. The rational and available coefficients of grouting circle in karst deep buried tunnel construction are drawn: the grouting ring thickness is 6 m and the hydraulic conductivity ratio of surrounding rock and lining is 100. In addition, the accuracy of the simplified formula was verified by the comparison of analytical solution and numerical analysis. This study provides a reliable calculation method for water inflow and lining water pressure of the deep buried tunnel and have certain reference value for the structural design of deep buried tunnel to reduce water inflow and ensure construction safety.

Analysis of optimum grid determination of water quality model with 3-D hydrodynamic model using environmental fluid dynamics code (EFDC)

Zhenhao Yin,Dongil Seo 대한환경공학회 2016 Environmental Engineering Research Vol.21 No.2

This study analyzes guidelines to select optimum number of grids to represent behavior of a given water system appropriately. The EFDC model was chosen as a 3-D hydrodynamic and water quality model and salt was chosen as a surrogate variable of pollutant. The model is applied to an artificial canal that receives salt water from coastal area and fresh water from a river from respective gate according to previously developed gate operation rule. Grids are subdivided in vertical and horizontal (longitudinal) directions, respectively until no significant changes are found in salinity concentrations. The optimum grid size was determined by comparing errors in average salt concentrations between a test grid systems against the most complicated grid system. MSE (mean squared error) and MAE (mean absolute error) are used to compare errors. The CFL (Courant-Friedrichs-Lewy) number was used to determine the optimum number of grid systems for the study site though it can be used when explicit numerical method is applied only. This study suggests errors seem acceptable when both MSE and MAE are less than unity approximately.

Comparative portrayal of ocular surface microbe with and without dry eye

ZhenHao Li,Yufang Gong,ShuZe Chen,SiQi Li,Yu Zhang,HuiMin Zhong,ZhouCheng Wang,YiFan Chen,QiXin Deng,YuTing Jiang,LiYing Li,Min Fu,GuoGuo Yi 한국미생물학회 2019 The journal of microbiology Vol.57 No.11

To compare the ocular surface (OS) microbial communities and diversity between dry eye (DE) and non-DE (NDE). Furthermore, we compared meibomian gland dysfunction (MGD) and non-MGD (NMGD) among DE subjects. The V3-V4 region of 16S rRNA gene high-throughput sequencing was performed in the conjunctival swab samples to investigate the composition of the OS bacterial community in DE (n=35) and NDE (n=54) and compared the composition of MGD (n=25) and NMGD (n=10) among DE subjects. Deep sequencing of OS 16S rDNA from DE (n=35) and NDE (n=54) demonstrated great a difference in alpha and beta diversity between the OS bacterial flora (P < 0.05). The similar OS microbial structures were shown at the phylum and genus levels by bioinformatics analysis between them, and in LEfSe (linear discriminant analysis effect size) analysis, Bacteroidia and Bacteroidetes were enriched in DE, while Pseudomonas was plentiful in NDE (linear discriminant analysis [LDA] > 4.0). Among the DE group, there was no significant difference in α and β diversity between MGD and NMGD (P > 0.05). Surprisingly, Bacilli was the dominant microbe in MGD, and Bacteroidetes was the superior bacteria in NMGD among DE subjects (LDA > 4.0). Different diversity of OS bacteria composition between DE and NDE and the altered diversity of OS bacteria may play an important role in DE. Moreover, the lower dominance of OS bacteria in DE may be associated with the occurrence and development of DE. Although there was no significant difference in alpha and beta analysis, the OS dominant microbe between MGD and NMGD among DE was different.

Comparative study for motion performance of the various FOWT platforms in waves

Zhenhao Song,Jeong-Seok Kim,Bo Woo Nam 한국해양환경·에너지학회 2021 한국해양환경공학회 학술대회논문집 Vol.2021 No.5

Recently, many countries have concentrated on the development of offshore wind power generation because of the limited space on land and considering the problems of noise and pollution. Compared with the nearshore wind resources, many countries, including China, America and Norway have found that more wind resources are existing in the deep water. For this reason, proper floating body for the FOWT which gives better motion performance in the deep sea is needed to be developed. In the deep sea, semi-submersible offshore platforms are currently most used as the support structure for FOWT since it is easier to install in actual engineering with lower cost compared with TLP and Spar. In this paper, a motion response analysis of different semisubmersible platforms for FOWT is carried out. In the present article, several semi-submersible supporting structure of floating offshore wind turbines concepts which have been already applied in the actual engineering installation are contained like Wind Float (Roddier et al., 2010), OC4-DeepCwind (Robertson et al., 2014). Additionally, some new designed platforms for the FOWT were also discussed. The main object of the present study is to investigate and compare the motion response of the platform due to the effect given by horizontal pontoon and damping plate respectively. Since the heave motion and pitch motion amplitude determine whether the wind turbine part will sink or not, and the pitch motion will affect the windward area which determine the efficiency of the electric generation, heave motion and pitch motion performance were discussed only in this article. The simulation tool used in this research is WADAM which is a commercial software developed by DNV GL based on the potential theory. For obtaining exact motion response results, except for the wave damping force, viscous damping force were also added manually by using a certain ratio of critical damping force. The viscous damping ratio value was calculated by comparing with a OC4 FOWT model test result (Koo et al., 2014). Besides, the FOWT platform models presented in previous studies were modified with equivalent displacement constraint and similar viscous damping ratio to evaluate the motion performance in fair comparing approach.

Study on Static and Dynamic Reliability of Main Girder of Cable-stayed Bridge Based on Subset Simulation Method

Zhenhao Zhang,Mengmeng Tao,Fuming Wang,Yi Yang,Lu Ke 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.2

For failure probability analysis of complex structures, the Monte Carlo method (MC) needs alarge number of samples and it is more inefficient in the case of small failure probability. Basedon the Subset Simulation (SS) and Subset Simulation Significant Sampling (SSIS), this paperanalyzes the static and dynamic reliability of main girder of cable-stayed bridge and realizesthe efficient solution of the failure probability of complex cable-stayed bridge. According toSS, MC sampling is performed on random variables. Finally, the critical values of intermediatefailure events are solved and automatically stratified, and then the failure probability of eachfailure mode is obtained by counting the number of samples in the failure domain. Accordingto SSIS method, SS method is optimized by introducing important sampling density function,which can make the sample points to fall in the structural failure areas as many as possible. The failure probability of main girder of cable-stayed bridge can be calculated more efficiently. Meanwhile, ANSYS-PDS template technique is used to perform the reliability and sensitivityanalysis of main girder of cable-stayed bridge. The failure probabilities obtained are very closeto the results of SS. The example analysis shows that for the reliability analysis of cable-stayedbridges, the sample size of SS and SSIS is 0.3% of MC, and the maximum relative difference isless than 3%. In addition the main beam section bending moment and wind speed have thegreatest impact on the reliability of the main beam of cable-stayed bridges.

Assessment of flexural and splitting strength of steel fiber reinforced concrete using automated neural network search

Zhang, Zhenhao,Paul, Suvash C.,Panda, Biranchi,Huang, Yuhao,Garg, Ankit,Zhang, Yi,Garg, Akhil,Zhang, Wengang Techno-Press 2020 Advances in concrete construction Vol.10 No.1

Flexural and splitting strength behavior of conventional concrete can significantly be improved by incorporating the fibers in it. A significant number of research studies have been conducted on various types of fibers and their influence on the tensile capacity of concrete. However, as an important property, tensile capacity of fiber reinforced concrete (FRC) is not modelled properly. Therefore, this paper intends to formulate a model based on experiments that show the relationship between the fiber properties such as the aspect ratio (length/diameter), fiber content, compressive strength, flexural strength and splitting strength of FRC. For the purpose of modeling, various FRC mixes only with steel fiber are adopted from the existing research papers. Automated neural network search (ANS) is then developed and used to investigate the effect of input parameters such as fiber content, aspect ratio and compressive strength to the output parameters of flexural and splitting strength of FRC. It is found that the ANS model can be used to predict the flexural and splitting strength of FRC in a sensible precision.

Experimental Study on the Mechanism of Intermittent Water and Mud Inrush Caused by Dredging and Rainfall considering Sedimentary Characteristics in Karst Tunnels

Xin Huang,Tong Wang,Zhenhao Xu,Zhengguo Zhu,Jiaqi Guo,Peng Lin,Yongchao Tian 대한토목학회 2023 KSCE Journal of Civil Engineering Vol.27 No.5

The mechanism of intermittent water and mud inrush is a difficult problem faced by disaster prevention and safe construction in karst tunnels. Aiming at revealing the mechanism of intermittent water and mud inrush, we developed an integrated testing system for filling medium deposition in karst caves and intermittent water and mud inrush. By conducting a serial of laboratory experiments, we analyzed the sedimentary characteristics of the filling medium in karst caves and the catastrophic process of intermittent water and mud inrush induced by dredging and rainfall under realistic sedimentary conditions. The results show that the filling medium exhibits layered deposition characteristics, which are affected by the water circulation time, the amount of sediments carried by water and the water flow rate. The first inrush incubation time reduces with the water head increases. The critical water head and the disaster incubation time increase with the deposition height increases. Under the same conditions, the first inrush incubation time of gravel type, silt type, and clay type filling medium decrease sequentially. The results can provide a theoretical basis for preventing intermittent water and mud inrush disasters in karst tunnels.

Detection of LSB Matching Revisited Using Pixel Difference Feature

( Wenxiang Li ),( Tao Zhang ),( Zhenhao Zhu ),( Yan Zhang ),( Xin Ping ) 한국인터넷정보학회 2013 KSII Transactions on Internet and Information Syst Vol.7 No.10

This paper presents a detection method for least significant bit matching revisited (LSBMR) steganography. Previous research shows that the adjacent pixels of natural images are highly correlated and the value 0 appears most frequently in pixel difference. Considering that the message embedding process of LSBMR steganography has a weighted-smoothing effect on the distribution of pixel difference, the frequency of the occurrence of value 0 in pixel difference changes most significantly whereas other values approximately remain unchanged during message embedding. By analyzing the effect of LSBMR steganography on pixel difference distribution, an equation is deduced to estimate the frequency of difference value 0 using the frequencies of difference values 1 and 2. The sum of the ratio of the estimated value to the actual value as well as the ratio of the frequency of difference value 1 to difference value 0 is used as the steganalytic detector. Experimental results show that the proposed method can effectively detect LSBMR steganography and can outperform previous proposed methods.