• Steel and Composite Structures
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• 제49권6호
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• pp.645-666
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• 2023

Due to the steadily declining supply of natural coarse aggregates, the concrete industry has shifted to substituting coarse aggregates generated from byproducts and industrial waste. Oil palm shell is a substantial waste product created during the production of palm oil (OPS). When considering the usage of OPSC, building engineers must consider its uniaxial compressive strength (UCS). Obtaining UCS is expensive and time-consuming, machine learning may help. This research established five innovative hybrid AI algorithms to predict UCS. Aquila optimizer (AO) is used with methods to discover optimum model parameters. Considered models are artificial neural network (AO - ANN), adaptive neuro-fuzzy inference system (AO - ANFIS), support vector regression (AO - SVR), random forest (AO - RF), and extreme gradient boosting (AO - XGB). To achieve this goal, a dataset of OPS-produced concrete specimens was compiled. The outputs depict that all five developed models have justifiable accuracy in UCS estimation process, showing the remarkable correlation between measured and estimated UCS and models' usefulness. All in all, findings depict that the proposed AO - XGB model performed more suitable than others in predicting UCS of OPSC (with R², RMSE, MAE, VAF and A_15-index at 0.9678, 1.4595, 1.1527, 97.6469, and 0.9077). The proposed model could be utilized in construction engineering to ensure enough mechanical workability of lightweight concrete and permit its safe usage for construction aims.

• 한국산학기술학회논문지
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• 제15권7호
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• pp.4100-4104
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• 2014

대중음악산업에서 이용매체의 변화는 음악 소비자들의 이용패턴의 변화와 함께 나타나며, 여러 매체의 복합적인 영향이 음악 소비자들의 선호도에 추가적인 영향을 미친다. 본 논문에서는 소유에서 소비로 빠르게 진화하고 있는 국내 음악 소비자들의 이용패턴을 AIDMA 모델과 AISAS 모델의 관점과 통계의 추이를 살펴보고 분석해 보았다.

• 전기학회논문지
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• 제67권3호
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• pp.460-466
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• 2018

For the efficient energy consumption in an urban railway station, it is necessary to know the patterns of electrical loads for each usage in detail. The electrical loads in an urban railway station have different characteristics from other normal electrical load, such as the peak load timing during a day. The lighting, HVAC, communication, and commercial loads make up large amount of electrical load for equipment in an urban railway station, and each of them has the unique specificity. These loads for each usage were estimated without measuring device by the polynomial regression method with big data such as total amount of electrical load and weather data. In the simulation with real data, the optimal polynomial regression model was third order polynomial regression model with 9 or 10 independent variables.

• 통상정보연구
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• 제8권2호
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• pp.3-35
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• 2006

Until now, most of the studies about the internet service have focused mainly on the adoption of on-line(wired) internet services, while there have relatively been very few studies about the adoption and usage of wireless or mobile internet services. The generic model explaining the adoption behaviors of wireless internet services has not been made yet. Previous studies of that area is not so easy to find. The purposes of this paper are two-folds. The first is to find the factors affecting the users' intention and commitment behavior of mobile internet services. The second is to find the relative importance of the factors in users making decisions about users' usage intention and commitment behavior. In the theoretical part of this paper, the precedent studies concerning the technology acceptance model and the theories of on-line internet services adoption, the theories of the mobile internet services, are reviewed and analyzed.

• 품질경영학회지
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• 제31권4호
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• pp.219-225
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• 2003

Two­dimensional warranty data can be modelled using two different approaches： two­dimensional point process and one­dimensional point process with usage as a function of age. The first approach has three different models. First of all, bivariate model is appealing but is not appropriate for explaining warranty claims. Next, the rest of the two models (marked point process, and counting and matching on both directions independently) are more appropriate for explaining warranty claims. However, the second one (counting and matching on both directions independently) assumes that the two variables (variables representing the two­dimensions) are independent. Last of all, one­dimensional point process with usage as a function of age is also promising to explain the two­dimensional warranty claims. But the models or variations of them need more investigation to be applicable to real warranty claim data.

• 산업공학
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• 제17권3호
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• pp.314-329
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• 2004

The rapid growth of investments in mobile service to reach a large and growing body of customers, coupled with low communication costs, has made user acceptance an increasingly critical management issue. The study draws upon the task-technology fit (TTF) model as its theoretical basis and its empirical findings to pragmatically explain the key factors that affect the performance and user acceptance of mobile service in medical field. A total of 110 usable responses were obtained. The findings indicate that the task, technology, and individual user characteristics positively affect task-technology fit and mobile service usage. The task-technology fit and mobile service usage are the dominant factors that affect mobile service performance. The result points out the importance of the fit between technologies and users' tasks in achieving individual performance impact from mobile service in medical arena.

• 한국신뢰성학회지:신뢰성응용연구
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• 제15권1호
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• pp.6-11
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• 2015

Maintenance plays an important role in keeping product availability, reliability and quality at an appropriate level. In this paper, two-types of maintenance policies are studied following the expiration of two-dimensional (2D) free replacement warranty. Both the fixed-maintenance-period policy and the variable-maintenance-period policy are based on a specified region of the warranty defined in terms of age and usage where all failures are minimally repaired. An accelerating failure time (AFT) model is used to allow for the effect of usage rate on product degradation. The maintenance model that arises following the expiration of 2D warranty is discussed. The expected cost rates per unit time from the user's point of view are formulated and the optimal maintenance policies are determined to minimize the expected cost rate to the user. Finally numerical examples are given to illustrate the optimal maintenance polices.

• 한국정보시스템학회지:정보시스템연구
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• 제14권2호
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• pp.133-154
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• 2005

The objective of this study is to find the factors influencing the use of mobile service. We extracted critical study variables according to literature reviews about adoption of information systems, those under the internet environment and mobile internet adoption for theoretical foundation. TAM suggested by Davis(1985) has explained the acceptance mechanism with the following constructs: perceived usefulness, perceived ease of use, attitude toward use, behavioral intention and actual usage. After studying prior literature reviews, this study investigated the group of people using mobile services. The result of study claims that it has same results with previous TAM, especially between personal innovativeness and attitude toward use have strong statistical relations. On the other hand, there haven't been any statistical relations between perceived ease of use and perceived usefulness and between perceived usefulness and behavioral intention, either. In conclusion, use of mobile service can be promoted by developing various kinds of mobile service, designing device and interface to use mobile service more convenience and familiar, stimulating user's innovative characters and recognizing mobile service more useful in real life.

• Journal of Information Technology Applications and Management
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• 제12권1호
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• pp.173-189
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• 2005

The technology acceptance model (TAM) is a lot of cited in information technology adoption and usage researches. TAM has a base in psychological research, is parsimonious, explains usage behavior quite well, and can be operationalized with valid and reliable instruments. But TAM has been conducted primarily in volitional environments of the adoption of new technology. This paper discusses technology acceptance in accounting information systems to examine TAM with subjective norm and perceived behavioral control in mandated using environments. The results show that in mandatory environments such as accounting information systems, subjective norm is not a significant effect on the behavioral intention. Perceived usefulness and perceived behavioral control are significant the factor on the behavioral intention. The implications of finding are that perceived usefulness and perceived behavioral control play major role in technology acceptance rather than subjective norm in accounting information systems with mandatory environments.

• Asia pacific journal of information systems
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• 제13권2호
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• pp.87-104
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• 2003

Though much attention has been paid to offer various multimedia services by many online service providers, the study on consumer behavior of online information service users are yet to be further explored in various aspects. This study develops a mathematical model for analyzing online consumer's usage patterns, contrasted to the existing media selection theory and flow concept about usage behavior of information services. We demonstrated using some case examples that online information consumption can be viewed not only as a cognitive behavior interacting with online media, but also as an economically rational behavior depending on consumer's perceived cost and time spending. The results obtained in this paper will surely serve as a theoretical foundation for justifying the consumer's behavior and WTP (willingness to pay) for various online contents consumption empirically.