• Title/Summary/Keyword: Model Validity

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Numerical analysis of dam breaking problem using SPH (제체의 갑작스런 붕괴로 인한 충격파 수치해석 - SPH (Smoothed Particle Hydrodynamics)를 중심으로)

  • Cho, Yong Jun;Kim, Gweon Su
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.28 no.3B
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    • pp.261-270
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    • 2008
  • Even though there is a great deal of progress in a numerical method of high caliber like SPH, it is very rarely deployed in a water resources community. Despite the great stride in computing environment, depth averaged approach like a nonlinear shallow equation is still efficient tool for flood routing in large watershed, but it can give some misleading information like the inundation height of flood. In this rationale, we numerically simulate the flow into the dry channel, dry channel with an obstacle triggered by the collapse of a two dimensional water column using SPH (Smoothed Particle Hydrodynamics) in order to boost the application of numerical method of high caliber like SPH in a water resources community. As a most severe test of the robustness of SPH, we also carry out the simulation of the flow through a clearance into the wet channel driven by the rapid removal of a water gate. As a hydrodynamic model, we used the Navier-Stokes equation, a numerical integration of which was carried out using SPH. To verify the validity of newly proposed numerical model, we compare the numerically simulated flow with the others in the literature mainly from VOF and MAC, and hydraulic experiments by Martin and Moyce (1952), Koshizuka et al. (1995) and Janosi et al. (2004). It was shown that agreements between the numerical results in this study and hydraulic experiments are remarkable.

Effects of Stiffness of Face Supporting Zone on Face Slab Behaviors of CFRD (CFRD 차수벽지지죤 강성이 콘크리트차수벽 거동에 미치는 영향)

  • Ha, Ik Soo;Seo, Min Woo;Kim, Hyoung Soo
    • KSCE Journal of Civil and Environmental Engineering Research
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    • v.26 no.5C
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    • pp.351-358
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    • 2006
  • The purpose of this study is to recommend the simulation method and procedure of behaviors of CFRD(Concrete Faced Rockfill Dam) concrete face slab with impoundment by centrifuge tests, to examine the effects of the flexural rigidity of the concrete face slab on the face slab deformation from the centrifuge tests, and to evaluate the effects of the stiffness of face supporting zone on the displacement and moment of face slab by numerical analysis which is verified by the centrifuge tests. In this study, the centrifuge tests on the two model dams with the concrete face slab of different flexural rigidity were carried out. Also, the centrifuge tests were simulated by numerical analysis of which input material properties were obtained by the triaxial tests on the model materials. The validity of numerical analysis was evaluated by comparison between the results of centrifuge tests and numerical simulation. The deformation pattern of the concrete face slab was examined with the various stiffness of the face supporting zone by numerical analysis. From the results of centrifuge tests, the effects of face slab thickness on the deformation of face slab were negligible. From the results of centrifuge tests and numerical analysis, it was found that the amplitude of the maximum displacement of face slab and the position where the maximum displacement was mobilized with impoundment were affected by the stiffness of face supporting zone rather than the flexural rigidity of concrete face slab.

Applying the Multiple Cue Probability Learning to Consumer Learning

  • Ahn, Sowon;Kim, Juyoung;Ha, Young-Won
    • Asia Marketing Journal
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    • v.15 no.3
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    • pp.159-172
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    • 2013
  • In the present study, we apply the multiple cue probability learning (MCPL) paradigm to examine consumer learning from feedback in repeated trials. This paradigm is useful in investigating consumer learning, especially learning the relationships between the overall quality and attributes. With this paradigm, we can analyze what people learn from repeated trials by using the lens model, i.e., whether it is knowledge or consistency. In addition to introducing this paradigm, we aim to demonstrate that knowledge people gain from repeated trials with feedback is robust enough to weaken one of the most often examined contextual effects, the asymmetric dominance effect. The experiment consists of learning session and a choice task and stimuli are sport rafting boats with motor engines. During the learning session, the participants are shown an option with three attributes and are asked to evaluate its overall quality and type in a number between 0 and 100. Then an expert's evaluation, a number between 0 and 100, is provided as feedback. This trial is repeated fifteen times with different sets of attributes, which comprises one learning session. Depending on the conditions, the participants do one (low) or three (high) learning sessions or do not go through any learning session (no learning). After learning session, the participants then are provided with either a core or an extended choice set to make a choice to examine if learning from feedback would weaken the asymmetric dominance effect. The experiment uses a between-subjects experimental design (2 × 3; core set vs. extended set; no vs. low vs. high learning). The results show that the participants evaluate the overall qualities more accurately with learning. They learn the true trade-off rule between attributes (increase in knowledge) and become more consistent in their evaluations. Regarding the choice task, there is a significant decrease in the percentage of choosing the target option in the extended sets with learning, which clearly demonstrates that learning decreases the magnitude of the asymmetric dominance effect. However, these results are significant only when no learning condition is compared either to low or high learning condition. There is no significant result between low and high learning conditions, which may be due to fatigue or reflect the characteristics of learning curve. The present study introduces the MCPL paradigm in examining consumer learning and demonstrates that learning from feedback increases both knowledge and consistency and weakens the asymmetric dominance effect. The latter result may suggest that the previous demonstrations of the asymmetric dominance effect are somewhat exaggerated. In a single choice setting, people do not have enough information or experience about the stimuli, which may lead them to depend mostly on the contextual structure among options. In the future, more realistic stimuli and real experts' judgments can be used to increase the external validity of study results. In addition, consumers often learn through repeated choices in real consumer settings. Therefore, what consumers learn from feedback in repeated choices would be an interesting topic to investigate.

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Progressive Damage and Failure Analysis of Open-Hole Composite Specimens Under Compressive Loading Using Finite Element Analysis (유한요소해석을 이용한 압축 하중을 받는 오픈 홀 복합재 시편의 점진적 손상 및 파손 분석)

  • Young Cheol Kim;Geunsu Joo;Hong-Kyu Jang;Jinbong Kim;Min-Gyu Kang;Woo-Kyoung Lee;Ji Hoon Kim
    • Composites Research
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    • v.36 no.5
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    • pp.303-309
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    • 2023
  • In this paper, a Progressive Damage and Failure Analysis (PDFA) modeling method was developed using ABAQUS/EXPLICIT to predict in-plane damage and delamination for Open-Hole Compression (OHC) testing. The proposed PDFA model was constructed based on Hashin criteria and cohesive behavior. The strength and stiffness of OHC specimens with three types of stacking sequences [(45/-45/02)3]s , [(45/0/-45/90)3]s and [45/-45/0/45/-45/90/(45/-45)2]s were compared to comprehensively evaluate the validity of the Finite Element(FE) model of PDFA. The strength and stiffness of the OHC specimens were predicted relatively well, with less than a percentage error 10.0 %. For the numerical simulation case for each layup, the damage initiation/evolution of OHC specimens were evaluated for delamination and tension/compression matrix damage before and after failure.

A Study on the Development of Mathematical-Informatics Linkage·Convergence Class Materials according to the Theme-Based Design Model (주제기반 설계 모형에 따른 수학-정보 연계·융합 수업 자료 개발 연구)

  • Lee, Dong Gun;Kim, Han Su
    • Communications of Mathematical Education
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    • v.37 no.3
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    • pp.517-544
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    • 2023
  • This study presents the process and outcomes of developing mathematical-informatics linkage·convergence class materials, based on previous research findings that indicate a lack of such materials in high schools despite the increasing need for development of interdisciplinary linkage·convergence class materials In particular, this research provides insights into the discussions of six teachers who participated in the same professional learning community program, aiming to create materials that are suitable for linkage·convergence class materials and highly practical for classroom implementation. Following the material development process, a theme-based design model was applied to create the materials. In alignment with prior research and consensus among teacher learning community members, mathematics and informatics teachers developed instructional materials that can be utilized together during a 100-minute block lesson. The developed materials utilize societal issue contexts to establish links between the two subjects, enabling students to engage in problem-solving through mathematical modeling and coding. To increase the validity and practicality of the developed resources during their field application, CVR verification was conducted involving field teachers. Incorporating the results of the CVR verification, the finalized instructional materials were presented in the form of a teaching guide. Furthermore, we aimed to provide insights into the trial-and-error experiences and deliberations of the developers throughout the material development process, with the intention of offering valuable information that can serve as a foundation for conducting related research by field researchers. These research findings hold value as empirical evidence that can explore the applicability of teaching material development models in fields. The accumulation of such materials is expected to facilitate a cyclical relationship between theoretical teaching models and practical classroom applications.

Investigating the Performance of Bayesian-based Feature Selection and Classification Approach to Social Media Sentiment Analysis (소셜미디어 감성분석을 위한 베이지안 속성 선택과 분류에 대한 연구)

  • Chang Min Kang;Kyun Sun Eo;Kun Chang Lee
    • Information Systems Review
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    • v.24 no.1
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    • pp.1-19
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    • 2022
  • Social media-based communication has become crucial part of our personal and official lives. Therefore, it is no surprise that social media sentiment analysis has emerged an important way of detecting potential customers' sentiment trends for all kinds of companies. However, social media sentiment analysis suffers from huge number of sentiment features obtained in the process of conducting the sentiment analysis. In this sense, this study proposes a novel method by using Bayesian Network. In this model MBFS (Markov Blanket-based Feature Selection) is used to reduce the number of sentiment features. To show the validity of our proposed model, we utilized online review data from Yelp, a famous social media about restaurant, bars, beauty salons evaluation and recommendation. We used a number of benchmarking feature selection methods like correlation-based feature selection, information gain, and gain ratio. A number of machine learning classifiers were also used for our validation tasks, like TAN, NBN, Sons & Spouses BN (Bayesian Network), Augmented Markov Blanket. Furthermore, we conducted Bayesian Network-based what-if analysis to see how the knowledge map between target node and related explanatory nodes could yield meaningful glimpse into what is going on in sentiments underlying the target dataset.

Penalized least distance estimator in the multivariate regression model (다변량 선형회귀모형의 벌점화 최소거리추정에 관한 연구)

  • Jungmin Shin;Jongkyeong Kang;Sungwan Bang
    • The Korean Journal of Applied Statistics
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    • v.37 no.1
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    • pp.1-12
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    • 2024
  • In many real-world data, multiple response variables are often dependent on the same set of explanatory variables. In particular, if several response variables are correlated with each other, simultaneous estimation considering the correlation between response variables might be more effective way than individual analysis by each response variable. In this multivariate regression analysis, least distance estimator (LDE) can estimate the regression coefficients simultaneously to minimize the distance between each training data and the estimates in a multidimensional Euclidean space. It provides a robustness for the outliers as well. In this paper, we examine the least distance estimation method in multivariate linear regression analysis, and furthermore, we present the penalized least distance estimator (PLDE) for efficient variable selection. The LDE technique applied with the adaptive group LASSO penalty term (AGLDE) is proposed in this study which can reflect the correlation between response variables in the model and can efficiently select variables according to the importance of explanatory variables. The validity of the proposed method was confirmed through simulations and real data analysis.

Comparison between village characteristics and habitat quality to application OECM in Nakdong-Jeongmaek (낙동정맥 내 OECM 적용 가능 지역 발굴을 위한 마을 특성과 서식지 질 비교)

  • Oh, Ju-Hyeong;Kim, Su-Jin;Kim, Tae-Su;Jang, Gab-Su;Jeon, Seong-Woo
    • Journal of the Korean Society of Environmental Restoration Technology
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    • v.26 no.6
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    • pp.51-65
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    • 2023
  • The Jeongmaeks are Korea's unique forest space recognition system that diverged from the Baekdudaegan. The Jeongmaeks are easily exposed to pressure because it is adjacent to the living area. Among them, Nakdong-Jeongmaek has high biodiversity, but damage is accelerating. According to the Convention on Biological Diversity (CBD) in 2022, the target is to expand the area of terrestrial and marine protected areas to 30% of national territory by 2030. As of September 2023, the area of terrestrial protected areas in South Korea is only 16.97% of the country's territory. This is due in part to the high proportion of private forests in the region, which makes it difficult to establish protected areas. Therefore, there is a need to establish Other Effective Area-based Conservation Measure (OECMs), which pursue complex and effective conservation that considers multiple values, as an alternative to protected areas. This study aims to identify areas suitable for OECM and to provide opinions on the establishment of appropriate management plans for each value using SOM and InVEST Habitat Quality model. This study evaluated the habitat quality of 206 villages located within 1km of the Nakdong-Jeongmaek and compared the characteristics of villages classified by SOM. As a result, the habitat quality was 0.867 for Tourism village (ClusterIV), 0.838 for Conservation village (ClusterVI), 0.835 for Mixed village (ClusterI), 0.796 for Production (ClusterV), 0.731 for Rural village (ClusterIII) and 0.625 for Urban village (ClusterII). When the distribution was identified through statistical analysis, the Kruskal-Wallis test showed that the distributions were not identical, with a p-value of 1.53e-08. Dunn's test showed a difference between Tourism, Conservation and Rural, Urban village. However, Mixed village was overestimated due to the lack of villages and the small area included in the study area. Moreover, Conservation village was somewhat under-evaluated in the analysis due to the use of a single weight for protected areas. It is necessary to perform additional reinforcement of the value evaluation of Jeongmaeks by conducting Forest Resource Survey and the National Natural Environment Survey. Therefore, we believe that sufficient validity for the establishment of OECMs in the Nakdong-Jeongmaek can be provided by addressing these limitations and conducting additional research.

Dual Path Model in Store Loyalty of Discount Store (대형마트 충성도의 이중경로모형)

  • Ji, Seong-Goo;Lee, Ihn-Goo
    • Journal of Distribution Research
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    • v.15 no.1
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    • pp.1-24
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    • 2010
  • I. Introduction The industry of domestic discount store was reorganized with 2 bigs and 1 middle, and then Home Plus took over Home Ever in 2008. In present, Oct, 2008, E-Mart has 118 outlets, Home Plus 112 outlets, and Lotte Mart 60 stores. With total number of 403 outlets, they are getting closer to a saturation point. We know that the industry of discount store has been getting through the mature stage in retail life cycle. There are many efforts to maintain existing customers rather than to get new customers. These competitions in this industry lead firms to acknowledge 'store loyalty' to be the first strategic tool for their sustainable competitiveness. In other words, the strategic goal of discount store is to boost up the repurchase rate of customers throughout increasing store loyalty. If owners of retail shops can figure out main factors for store loyalty, they can easily make more efficient and effective retail strategies which bring about more sales and profits. In this practical sense, there are many papers which are focusing on the antecedents of store loyalty. Many researchers have been inspecting causal relationships between antecedents and store loyalty; store characteristics, store image, atmosphere in store, sales promotion in store, service quality, customer characteristics, crowding, switching cost, trust, satisfaction, commitment, etc., In recent times, many academic researchers and practitioners have been interested in 'dual path model for service loyalty'. There are two paths in store loyalty. First path has an emphasis on symbolic and emotional dimension of service brand, and second path focuses on quality of product and service. We will call the former an extrinsic path and call the latter an intrinsic path. This means that consumers' cognitive path for store loyalty is not single but dual. Existing studies for dual path model are as follows; First, in extrinsic path, some papers in domestic settings show that there is 'store personality-identification-loyalty' path. Second, service quality has an effect on loyalty, which is a behavioral variable, in the mediation of customer satisfaction. But, it's very difficult to find out an empirical paper applied to domestic discount store based on this mediating model. The domestic research for store loyalty concentrates on not only intrinsic path but also extrinsic path. Relatively, an attention for intrinsic path is scarce. And then, we acknowledge that there should be a need for integrating extrinsic and intrinsic path. Also, in terms of retail industry, this study is meaningful because retailers want to achieve their competitiveness by using store loyalty. And so, the purpose of this paper is to integrate and complement two existing paths into one specific model, dual path model. This model includes both intrinsic and extrinsic path for store loyalty. With this research, we would expect to understand the full process of forming customers' store loyalty which had not been clearly explained. In other words, we propose the dual path model for discount store loyalty which has been originated from store personality and service quality. This model is composed of extrinsic path, discount store personality$\rightarrow$store identification$\rightarrow$store loyalty, and intrinsic path, service quality of discount store$\rightarrow$customer satisfaction$\rightarrow$store loyalty. II. Research Model Dual path model integrates intrinsic path and extrinsic path into one specific model. Intrinsic path put an emphasis on quality characteristics and extrinsic path focuses on brand characteristics. Intrinsic path is based on information processing perspective, and extrinsic path emphasizes symbolic and emotional dimension of brand. This model is composed of extrinsic path, discount store personality$\rightarrow$store identification$\rightarrow$store loyalty, and intrinsic path, service quality of discount store$\rightarrow$customer satisfaction$\rightarrow$store loyalty. Hypotheses are as follows; Hypothesis 1: Service quality perceived by customers in discount store has an positive effect on customer satisfaction Hypothesis 2: Store personality perceived by customers in discount store has an positive effect on store identification Hypothesis 3: Customer satisfaction in discount store has an positive effect on store loyalty. Hypothesis 4: Store identification has an positive effect on store loyalty. III. Results and Implications We examined consumers who patronize discount stores for samples of this study. With the structural equation model(SEM) analysis, we empirically tested the validity and fitness of the dual path model for store loyalty in discount stores. As results, the fitness indices of this model were well fitted to data obtained. In an intrinsic path, service quality(SQ) is positively related to customer satisfaction(CS), customer satisfaction(CS) has very significantly positive effect on store loyalty(SL). Also, in an extrinsic path, the store personality(SP) is positively related to store identification(SI), it shows significant effect on store loyalty. Table 1 shows the results as follows; There are some theoretical and practical implications. First, Many studies on discount store loyalty have been executed from various perspectives. But there has been no integrative view on this issue. And so, this research was theoretically designed to integrate various and controversial arguments into one systematic model. We empirically tested dual path model forming store loyalty, and brought up a systematic and integrative framework for future studies. We want to expect creative and aggressive research activities. Second, a few established papers are focused on the relationship between antecedents and store loyalty; store characteristics, atmosphere, sales promotion in store, service quality, trust, commitment, etc., There has been some limits in understanding thoroughly the formation process of store loyalty with a singular path, intrinsic or extrinsic. Beyond these limits in single path, we could propose the new path for store loyalty. This is meaningful. Third, discount store firms make and execute marketing strategies for increasing store loyalty. This research provides real practitioners with reference framework needed for actual strategy formation. Because this paper shows integrated and systematic path for store loyalty. A special feature of this study is to represent 6 sub dimensions of service quality in intrinsic path and 4 sub dimensions of store personality in extrinsic path. Marketers can make more analytic marketing planning with concrete sub dimensions of service quality and store personality. When marketers of discount stores make strategic planning like MPR, Ads, campaign, sales promotion, they can use many items which are more competitive than competitors.

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The Effect of E-SERVQUAL on e-Loyalty for Apparel Online Shopping (재망상복장구물중전자(在网上服装购物中电子)E-SERVQUAL 대전자충성도적영향(对电子忠诚度的影响))

  • Kim, Eun-Young;Jackson, Vanessa P.
    • Journal of Global Scholars of Marketing Science
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    • v.19 no.4
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    • pp.57-63
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    • 2009
  • With an exponential increase in electronic commerce (e-commerce), marketers are attempting to gain a competitive advantage by emphasizing service quality and post interaction service aspects, which leads to customer satisfaction or behavioral consequence. Particularly for apparel, service quality is one of the key determinants in encouraging customer e-loyalty, and hence the success of apparel retailing in the context of electronic commerce. Therefore, this study explores e-service quality (E-SERVQUAL) factors and their unique effects on e-loyalty for apparel online shopping based on Parasuraman et al' s (2005) framework. Specific objectives of this study are to identify underlying dimension of E-SERVQUAL, and analyze a structural model for examining the effect of E-SERVQUAL on e-loyalty for online apparel shopping. For the theoretical framework of service quality in the context of online shopping, literatures on traditional and electronic service quality factors were comparatively reviewed, and two aspects of core and recovery services were identified. This study hypothesized that E-SERVQUAL has an effect on e-loyalty; customer satisfaction has a positive effect on e-service loyalty for apparel online shopping; and customer satisfaction mediates in the effect of E-SERVQUAL on e-loyalty for apparel online shopping. A self-administered questionnaire was developed based on literatures. A total of 252 usable questionnaires were obtained from online consumers who had purchase experience with online shopping for apparel products and reside in standard metropolitan areas, in the United States. Factor analysis (e.g., exploratory, confirmatory) was conducted to assess the validity and reliability and the structural equation model including measurement and structural models was estimated via LISREL 8.8 program. Findings showed that the E-SERVQUAL of shopping websites for apparel consisted of five factors: Compensation, Fulfillment, Efficiency, System Availability, and Responsiveness. This supports Parasuraman (2005)'s E-S-QUAL encompassing two aspects of core service (e.g., fulfillment, efficiency, system availability) and recovery related service (e.g., compensation, responsiveness) in the context of apparel shopping online. In the structural equation model, there are five exogenous latent variables for e-SERVQUAL factors; and two endogenous latent variables (e.g., customer satisfaction, e-loyalty). For the measurement model, the factor loadings for each respective construct were statistically significant and were greater than .60 and internal consistency reliabilities ranged from .85 to .88. In the estimated structural model of the e-SERVEQUAL factors, the system availability was found to have direct and positive effect on e-loyalty, whereas efficiency had a negative effect on e-loyalty for apparel online shopping. However, fulfillment was not a significant predictor for explaining consequences of E-SERVQUAL for apparel online shopping. This finding implies that perceived service quality of system available was likely to increase customer satisfaction for apparel online shopping. However, it was not supported that e-loyalty was determined by service quality, because service quality has an indirect effect on e-loyalty (i.e., repurchase intention) by mediating effect of value or satisfaction in the context of online shopping for apparel. In addition, both compensation and responsiveness were found to have a significant impact on customer satisfaction, which influenced e-loyalty for apparel online shopping. Thus, there was significant indirect effect of compensation and responsiveness on e-loyalty. This suggests that the recovery-specific service factors play an important role in maximizing customer satisfaction levels and then maintaining customer loyalty to the online shopping site for apparel. The findings have both managerial and research implications. Fashion marketers can establish long-term relationship with their customers based on continuously measuring customer perceptions for recovery-related service quality, such as quick responses to problem and returns, and compensation for customers' problem after their purchases. In order to maintain e-loyalty, recovery services play an important role in the first choice websites for consumers to purchase clothing. Given that online consumers may shop anywhere, a marketing strategy for improving competitive advantages is to provide better service quality, maximize satisfaction, and turn to creating customers' e-loyalty for apparel online shopping. From a researcher's perspective, there are some limitations of this research that should be considered when interpreting its findings. For future research, findings provide a basis for the further study of this important topic along both theoretical and empirical dimensions. Based on the findings, more comprehensive models for predicting E-SERVQUAL's consequences can be developed and tested. For global fashion marketing, this study can expand to a cross-cultural approach into e-service quality for apparel by including multinational samples.

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