• Journal of Korean Elementary Science Education
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• v.30 no.3
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• pp.353-366
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• 2011

An alternative vision for science inquiry that appears to be important and challenging is model-based inquiry in which students generate, evaluate and revise their explanatory model. Pre-service teachers should be given opportunities to develop and use their mechanistic explanatory models in order to participate in the practice of science and to have a sound understanding of science. With this view, this study described a case of pre-service elementary teachers' scientific modeling in magnetism. The aims of this study were to explore difficulties preservice elementary teachers encountered while they engaged in a model-based inquiry, and to examine how their understandings of the nature of scientific models changed after the model-based inquiry. The data analysis revealed that the pre-service teachers had difficulties in drawing and writing their own thinking because they had little experience of expressing their own science ideas. When asked to predict what would happen, they could not understand what it meant to make a prediction "based on their model". They did not know how to use or consider their model in making a prediction. At the end of the model-based inquiry they reached a final consensus of a best model. However, they were very anxious about whether the model was the "correct" answer. With respect to the nature of scientific models, almost all of the pre-service teachers initially viewed models only as a communication tool among scientists or students and teachers to help understand others' ideas. After the model-based inquiry, however, many of them understood that they could create, test, and revise their "own" models "by themselves". They also realized the key aspects of scientific models that a model can be changed as evidence is accumulated and a model is a knowledge production tool as well as a communication tool. The results indicated that pre-service elementary teachers' understandings of the nature of scientific models and their previous school science experiences could affect their performance on a model-based inquiry, and their experience of scientific modeling could help them enhance their understandings of the nature of scientific models.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.37 no.4
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• pp.90-97
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• 2014

The mobile SNS is a promising e-service platform of the future. However, measuring its service quality is a challenge. An appropriate model for measuring service quality is required. This paper proposes e-service quality models for analyzing mobile SNS platform quality, based on previous service quality researches. An empirical study is performed on the proposed models. The results show that constructs of existing e-service models such as responsiveness and assurance do not fit the mobile SNS platform, and that loyalty and value are better measures for mobile service quality.

• The Journal of Information Systems
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• v.28 no.3
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• pp.227-247
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• 2019

Purpose The purpose of this study is to identify the needs of art education suppliers and consumers and develop service models for an art education platform. In order to overcome the limitations of existing services limited to instructor-student customizing functions, our services take into account comprehensive relationships among various stakeholders and activities that constitute the art ecosystem Design/methodology/approach We reviewed the relevant reference and conducted interviews and surveys with stakeholders of art education market, so that identified the demand and functional priorities. Findings We identified the demand and functional priorities for customizing to as to develop major service models(i.e. service models for lessons, cubes, and businesses) for the art education platform.

• Journal of Communications and Networks
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• v.15 no.2
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• pp.228-239
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• 2013

Peer-to-peer (P2P) systems have proved the most effective and popular file sharing applications in recent years. Previous studies mainly focused on equal service and differentiated service strategies when peers have no initial data before their downloads. For an upload-constrained P2P file sharing system, we model both the equal service process and the differentiated service process when the initial data distribution of peers satisfies some special conditions. Moreover, we show how to minimize the time required to distribute the file to any number of peers. The proposed fluid-based models can reveal the intrinsic relations among the initial data amount, the peer set size, and the minimum last finish time. The closed-form expressions derived from the extended models can closely approximate chunk-based models and systems, especially for relatively large files. As an application of the extended models, we show how to provide differentiated service efficiently to multiple peer sets. Since no limits are imposed on the upload bandwidth of peers or the size of each peer set, we believe that our analytic process and the results achieved can provide not only fundamental insights into bandwidth allocation and data scheduling but also a helpful reference for both improving system performance and building an effective incentive mechanism for P2P file sharing systems.

• Journal of Korean Elementary Science Education
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• v.40 no.1
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• pp.1-12
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• 2021

This study investigated pre-service elementary teachers' understanding of the planetary revolution movement of Mars and their explanatory models to show how the Sun-Earth-Mars system worked. An assessment item set using five celestial maps drawn from the Stellarium was designed to probe pre-service teachers' understanding of the prograde-retrograde motion of Mars. Among 23 participants, only four showed scientifically accurate understanding of Mars movement and drawing correct explanatory models for the planetary movement. Even the pre-service teachers who construed correctly prograde and retrograde motions of Mars showed a clockwise movement model due to their intuitive perceptions of Mars movement data from the celestial maps. Pre-service teachers with poor understanding of planetary movement also showed weak explanatory models due to their limited observation or lower spatial thinking. Although the planetary motion is not an easy topic for pre-service elementary teachers, it can be argued if the alternative approach, such as using appropriate observational data of a planet and changing the frames of reference between Earth-based view and Space-based view, is employed effectively in teaching planetary motion, pre-service teachers can reach the upper level of leaning planetary motion in terms of the planet's revolution.

• International Journal of Reliability and Applications
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• v.8 no.2
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• pp.183-197
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• 2007

There is a growing trend for asset intensive industries to outsource maintenance services of their complex assets since outsourcing through service contract reduces upfront investments in infrastructure, expertise and specialised maintenance facilities. Estimation of costs for such contracts is complex and it is important to the user and the service providers for economic variability. The service provider's profit is influenced by many factors such as the terms of the contract, reliability of asset, and the servicing strategies, costs of resources needed to carryout maintenance. There is a need to develop mathematical models for understanding future costs to build it into the contract price. Three policies for service contracts are proposed in this paper considering the concepts of outsourcing maintenance service of assets to the service providers. Conceptual models are developed for estimating servicing costs of outsourcing through service contracts by considering time dependent failure mode.

• Journal of Korean Society for Quality Management
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• v.17 no.2
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• pp.142-148
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• 1989

In order to determine the level of service which minimizes the total of expected cost of service and the expected cost of waiting for that service, the important considerations are to evaluate the distance traveled to and from a service facility (D) and the expected number of mechanics in queueing system (L). The travel-time models are very useful when the servers must travel to the customer from the service facility. Thus, in this paper we studied on the determination of the optimal service level by the travel-time models. In order to decide the optimal service level, (D) has been introduced as a uniform distribution and (L) has been introduced as M/M/S model of queueing theory.

• Analytical Science and Technology
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• v.34 no.5
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• pp.231-239
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• 2021

Detection of fire accelerants from fire residues is critical to determine whether the case was arson or accidental fire. However, to develop a standardized model for determining the presence or absence of fire accelerants was not easy because of high temperature which cause disappearance or combustion of components of fire accelerants. In this study, logistic regression, random forest, and support vector machine models were trained and evaluated from a total of 728 GC-MS analysis data obtained from actual fire residues. Mean classification accuracies of the three models were 63 %, 81 %, and 84 %, respectively, and in particular, mean AU-PR values of the three models were evaluated as 0.68, 0.86, and 0.86, respectively, showing fine performances of random forest and support vector machine models.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.34 no.4
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• pp.145-151
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• 2011

In the information system service sectors, it is crucial to measure the quality of service. Especially factors determining the quality of service should be identified. For that purpose, in this study, the factors of two research models-SERVQUAL and TAM-are compared, analyzed and tested with data of public procurement system service. The result shows that the factors identified include reliability and assurance of SERVQUAL and perceived usefulness and perceived ease-of-use of TAM. Also, it is observed that the two models sufficiently explain the variance of satisfaction. This study may help improve the quality of information system service.

• Journal of Service Research and Studies
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• v.11 no.2
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• pp.95-105
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• 2021

The purpose of this study is to improve the accuracy of service satisfaction by utilizing KSC (Kano, Score Model, Concept Position) analysis methods in order to present various fitness center service models for healthy new silver generation centered on P fitness center which runs six branches in Busan. Double Diamond-based methods led to a case study focused on the P fitness center's Yeon-san branch which well leading in a wide variety of leisure infrastructures for the senior citizens. Throughout this study, based on the insights extracted from the customers were culminating in nine service design models from the perspective of administrators and trainers. The final derived nine models have been evaluated by Kano's satisfaction evaluation, Concept score, and Concept position evaluation. All of the nine models results indicated as valid except for models 3 and 6. Finally, an implementation roadmap was proposed by dividing it into investment cost and effectiveness.