• 제목/요약/키워드: Empirical modelling

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A BIM-based model for constructability assessment of conceptual design

  • Fadoul, Abdelaziz;Tizani, Walid;Koch, Christian
    • Advances in Computational Design
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    • 제3권4호
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    • pp.367-384
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    • 2018
  • The consideration of constructability issues at the design stage can lead to improved construction performance with smooth project delivery and savings in time and money. Empirical studies demonstrate the value obtained by integrating construction knowledge with the building design process, and its benefits for owners, contractors and designers. However, it is still a challenge to implement the concept into current design practice. There is a need for a decision support tool to aid designers in reviewing their design constructability, deploying current technological tools, such as BIM. Such tools are beneficial at the conceptual design stage when there is a room to improve the design significantly with less incurred cost. This research investigates how current process- and object-oriented models can be used to assess design constructability. It proposes a BIM-based model using embedded information within the design environment to conduct the assessment. The modelling framework is demonstrated in four key parts; namely, the conceptual design model, the constructability assessment model, the assessment process model and the decision-making phase. Each is associated with a set of components and functions that contribute towards the targeted constructability assessment outcomes. The proposed framework is the first to combine a numerical assessment system and a rule-based system, allowing for both quantitative and qualitative approaches. The modelling framework and its implementation through a prototype are described in this paper. It is believed that this framework is the first to enable users to transfer their construction knowledge and experience directly into a design platform linked to BIM models. The assessment criteria can be customised by the users who can reflect their own constructability preferences into various specialised profiles that can be added to the constructability assessment model. It also allows for the integration of the assessment process with the design phase, facilitating the optimisation of constructability performance from the early design stage.

Global Big Data Analysis Exploring the Determinants of Application Ratings: Evidence from the Google Play Store

  • Seo, Min-Kyo;Yang, Oh-Suk;Yang, Yoon-Ho
    • Journal of Korea Trade
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    • 제24권7호
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    • pp.1-28
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    • 2020
  • Purpose - This paper empirically investigates the predictors and main determinants of consumers' ratings of mobile applications in the Google Play Store. Using a linear and nonlinear model comparison to identify the function of users' review, in determining application rating across countries, this study estimates the direct effects of users' reviews on the application rating. In addition, extending our modelling into a sentimental analysis, this paper also aims to explore the effects of review polarity and subjectivity on the application rating, followed by an examination of the moderating effect of user reviews on the polarity-rating and subjectivity-rating relationships. Design/methodology - Our empirical model considers nonlinear association as well as linear causality between features and targets. This study employs competing theoretical frameworks - multiple regression, decision-tree and neural network models - to identify the predictors and main determinants of app ratings, using data from the Google Play Store. Using a cross-validation method, our analysis investigates the direct and moderating effects of predictors and main determinants of application ratings in a global app market. Findings - The main findings of this study can be summarized as follows: the number of user's review is positively associated with the ratings of a given app and it positively moderates the polarity-rating relationship. Applying the review polarity measured by a sentimental analysis to the modelling, it was found that the polarity is not significantly associated with the rating. This result best applies to the function of both positive and negative reviews in playing a word-of-mouth role, as well as serving as a channel for communication, leading to product innovation. Originality/value - Applying a proxy measured by binomial figures, previous studies have predominantly focused on positive and negative sentiment in examining the determinants of app ratings, assuming that they are significantly associated. Given the constraints to measurement of sentiment in current research, this paper employs sentimental analysis to measure the real integer for users' polarity and subjectivity. This paper also seeks to compare the suitability of three distinct models - linear regression, decision-tree and neural network models. Although a comparison between methodologies has long been considered important to the empirical approach, it has hitherto been underexplored in studies on the app market.

Numerical investigation of the impact of geological discontinuities on the propagation of ground vibrations

  • Haghnejad, Ali;Ahangari, Kaveh;Moarefvand, Parviz;Goshtasbi, Kamran
    • Geomechanics and Engineering
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    • 제14권6호
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    • pp.545-552
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    • 2018
  • Blast-induced ground vibrations by a significant amount of explosives may cause many problems for mining slope stability. Geological discontinuities have a significant influence on the transmission of dynamic pressure of detonation and according to their position relative to the slope face may have damaging or useful impacts on the slope stability. In this study, the effect of geological discontinuities was investigated by modelling a slope with geological discontinuities through applying the dynamic pressure in three-dimensional discrete element code (3DEC). The geological discontinuities in four states that generally apperceived in mine slopes are considered. Given the advantages of the pressure decay function defined by some researcher, this type of function was used to develop the pressure-time profile. The peak particle velocities (PPV) values were monitored along an axis by utilization of Fish programming language and the results were used as an indicator to measure the effects. As shown in the discontinuity-free model, PPV empirical models are reliable in rocks lacking discontinuities or tightly jointed rock masses. According to the other results, the empirical models cannot be used for the case where the rock mass contains discontinuities with any direction or dip. With regard to PPVs, when the direction of discontinuities is opposite to that of the slope face, the dynamic pressure of detonation is significantly damped toward the slope direction at the surface of discontinuities. On the other hand, when the discontinuities are horizontal, the dynamic pressure of detonation affects the rock mass to a large distance.

감정노동이 반생산적 과업행동에 미치는 영향에 관한 연구: 직무만족과 조직몰입을 매개로 (A Study on the Effects of Emotional Labor on Counterproductive Work Behavior: Mediated by Job Satisfaction and Organizational Commitment)

  • 한나영;배상욱
    • 한국산학기술학회논문지
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    • 제16권10호
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    • pp.7157-7165
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    • 2015
  • 본 연구는 의료기관 종사자들의 감정노동과 직무만족, 조직몰입 및 반생산적 과업행동 간의 관계를 통합적으로 살펴보기 위하여 의료기관 종사자들을 대상으로 설문조사를 실시하고 공변량 구조방정식모형을 통해 실증분석을 하였다. 실증분석 결과 첫째, 감정노동 차원 중 감정표현빈도는 직무만족에 유의적인 영향을 미치지 않는 것으로 나타났으나 감정표현주의정도, 감정부조화는 직무만족에 부(-)의 유의적인 영향을 미치는 것으로 나타났다. 둘째, 직무만족은 조직몰입에 정(+)의 유의적인 영향을 미치는 것으로 나타났으며 셋째, 조직몰입은 개인 조직 대상 반생산적 과업행동 모두에 부(-)의 유의적인 영향을 미치는 것으로 나타났다. 본 연구결과는 의료기관 종사자들이 직무를 수행하는데 있어 감정노동이 부정적인 결과를 초래하기 때문에 그들이 업무수행 중에 겪게 되는 감정노동을 경감시킬 수 있는 방안에 관심을 가질 필요가 있다는 것을 보여주고 있다

EPB tunneling in cohesionless soils: A study on Tabriz Metro settlements

  • Rezaei, Amir H.;Shirzehhagh, Mojtaba;Golpasand, Mohammad R. Baghban
    • Geomechanics and Engineering
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    • 제19권2호
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    • pp.153-165
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    • 2019
  • A case study of monitoring and analysis of surface settlement induced by tunneling of Tabriz metro line 2 (TML2) is presented in this paper. The TML2 single tunnel has been excavated using earth pressure balanced TBM with a cutting-wheel diameter of 9.49 m since 2015. Presented measurements of surface settlements, were collected during the construction of western part of the project (between west depot and S02 station) where the tunnel was being excavated in sand and silt, below the water table and at an average axis depth of about 16 m. Settlement readings were back-analyzed using Gaussian formula, both in longitudinal and transversal directions, in order to estimate volume loss and settlement trough width factor. In addition to settlements, face support and tail grouting pressures were monitored, providing a comprehensive description of the EPB performance. Using the gap model, volume loss prediction was carried out. Also, COB empirical method for determination of the face pressure was employed in order to compare with field monitored data. Likewise, FE simulation was used in various sections employing the code Simulia ABAQUS, to investigate the efficiency of numerical modelling for the estimating of the tunneling induced-surface settlements under such a geotechnical condition. In this regard, the main aspects of a mechanized excavation were simulated. For the studied sections, numerical simulation is not capable of reproducing the high values of in-situ-measured surface settlements, applying Mohr-Coulomb constitutive law for soil. Based on results, for the mentioned case study, the range of estimated volume loss mostly varies from 0.2% to 0.7%, having an average value of 0.45%.

Social Support for Social Commerce: An Empirical Study with Trust as a Mediator and Culture as Moderator

  • Hossain, Md. Alamgir;Jahan, Nusrat;Kim, Minho;Yesmin, Most. Nirufer;Hasan, Raquibul
    • Journal of Korea Trade
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    • 제25권7호
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    • pp.75-91
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    • 2021
  • Purpose - Social commerce (SC) is the growth of social media highlighting the e-commerce transactions and currently, the greatest challenges of e-commerce have attracted the influence of trust in social commerce intention (SCI). Based on the challenge, the study's purpose is to discover the effect of social support (informational and emotional support) on the SCI. The study also explores the mediation effect of trust and the moderation impact of culture between the USA and Korea. Design/methodology - This study used a sample of 482 surveys filled out by online shoppers from the US and Korea, two countries with divergent cultural values. Structural equation modelling (SEM) is used to analyze the hypothetical paths. In addition, bootstrapping and multi-group analysis are perform to view mediation and moderation effects respectively. Findings - The results of our study shows that both informational and emotional support significantly influences trust and SCI. Our results also supports the mediating effect of trust in social support and the moderating effect of culture in forming SCI. Originality/value - Our empirical results provide important information to businesses formulating cross-cultural SC strategies. This will help SC companies to analyze the aspects of customer trust through social support, which in turn will increase SCI and thereby established a competitive position for SCs. Our results will also be holistic directions for SC vendors in cross-cultural settings, which will offer important social and economic contributions to the sustainable growth of SC's business.

학교 청소년의 인터넷중독 현상의 영향요인에 관한 연구 (A Study of the Key Factors on the Internet Addiction of the Youth)

  • 신동로;백현기;강정화
    • 디지털융복합연구
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    • 제6권3호
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    • pp.93-107
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    • 2008
  • The aim of this study was to draw some suggestions for Internet Policy by using empirical analyses of key factors in Internet addiction in youths. Internet addiction in youths is perceived as a current and significant issue throughout the world. For the purpose of this study, factors that have influence on the Internet addiction of the youth have been explored and analysed empirically of its hypothetical relationships by using the SEM(structural equation modelling). As a result, a few key factors that suggest a strong relationship to Internet addiction in youths have been drawn: subjects' personality, accessibility to the Internet, psychology and communication factor. Particularly accessibility to the Internet, and specifically the duration of time spent online causes the phenomenon of the Internet addiction. This study shows, however, the subjects' personality and communication factor have the most significant causal relationship to Internet addiction. In other word, the Internet addiction has been changing with the various factors including the factors drawn in this study, which are subjects' personality, accessibility to the Internet, psychology and communication factor. Therefore, Internet addiction should not be merely treated as the isolated problem of the Internet itself; rather it should be understood as various dimensions of society, economy, culture etc. Furthermore, some alternatives to deal with the Internet addiction should be found in various approaches.

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An Empirical Investigation of the Impact of Customer Learning on Customer Experience in the Context of Knowledge Product Use

  • KIM, Yong Jin;YIM, Myung-Seong
    • The Journal of Asian Finance, Economics and Business
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    • 제7권12호
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    • pp.969-976
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    • 2020
  • The role of customers has changed from that of passive users to value co-creators. Therefore, it is important to understand how customer learning takes place and how it affects customer experiences with services and products. However, while past studies insist on the importance of the issues in designing customer experiences, they do not empirically address these issues. This study investigates the support processes for customer learning, and their impact on customer learning, which in turn influences customer experience. To test the hypotheses, we employed the survey method. Target informants were the actual users of Apple iPods. A total of 200 survey questionnaires were distributed and 146 were collected. Among these, seven erroneous responses were excluded, leaving 139 usable ones. The proposed model was empirically analyzed using the Covariance-based SEM (Structural Equation Modelling) technique. The findings of this study suggest that, among the three support processes in customer learning, learning-by-doing support and learning-by-investment support positively affect customer learning, which influences customer experience. This study contributes to the literature by identifying different types of support for different kinds of customer learning processes and by empirically testing the impact of the support for the process on customer learning, and in turn, its impact on customer experience.

Estimation of Hydrodynamic Coefficients from Sea Trials Using a System Identification Method

  • Kim, Daewon;Benedict, Knud;Paschen, Mathias
    • 해양환경안전학회지
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    • 제23권3호
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    • pp.258-265
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    • 2017
  • This paper validates a system identification method using mathematical optimization using sea trial measurement data as a benchmark. A fast time simulation tool, SIMOPT, and a Rheinmetall Defence mathematical model have been adopted to conduct initial hydrodynamic coefficient estimation and simulate ship modelling. Calibration for the environmental effect of sea trial measurement and sensitivity analysis have been carried out to enable a simple and efficient optimization process. The optimization process consists of three steps, and each step controls different coefficients according to the corresponding manoeuvre. Optimization result of Step 1, an optimization for coefficient on x-axis, was similar compared to values applying an empirical regression formulae by Clarke and Norrbin, which is used for SIMOPT. Results of Steps 2 and 3, which are for linear coefficients and nonlinear coefficients, respectively, was differ from the calculation results of the method by Clarke and Norrbin. A comparison for ship trajectory of simulation results from the benchmark and optimization results indicated that the suggested stepwise optimization method enables a coefficient tuning in a mathematical way.

Hydraulic conductivity of cemented sand from experiments and 3D Image based numerical analysis

  • Subramanian, Sathya;Zhang, Yi;Vinoth, Ganapathiraman;Moon, Juhyuk;Ku, Taeseo
    • Geomechanics and Engineering
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    • 제21권5호
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    • pp.423-432
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    • 2020
  • Hydraulic conductivity is one of the engineering properties of soil. This study focusses on the influence of cement content on the hydraulic conductivity of cemented sand, which is investigated based on the results from numerical analysis and laboratory testing. For numerical analysis the cemented samples were scanned using X-ray Computed Tomography (CT) while laboratory testing was carried out using a triaxial setup. Numerical analysis enables us to simulate flow through the sample and provides insight to the microstructure. It quantifies the pore volume, proportion of interconnected voids and pore size distribution in both cemented and uncemented samples, which could be computed only through empirical equations in case of laboratory testing. With reduction in global voids, the interconnecting voids within the samples also reduce with cement content. Gamma cumulative distribution function is used to predict the percentage of voids lesser than a given pore volume. Finally, the results obtained from both numerical analysis and laboratory testing are compared.