• Research in Mathematical Education
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• v.8 no.1
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• pp.19-30
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• 2004

This research applies the discursive approach to investigate the social transformation of students' conceptual model of differential equations. The analysis focuses on the students' use of metaphor in class in order to find kinds of metaphor used, their characteristics, and a pattern in the use of metaphor. Based on the analysis, it is concluded that the students' conceptual model of differential equations gradually becomes transformed with respect to the historical and cultural structure of the communal practice of mathematics. The findings suggest that through participating in the daily practice of mathematics as a historical and cultural product, a learner becomes socially transformed to a certain kind of a cultural being with historicity. This implies that mathematics education is concerned with the formation of historical and cultural identity at a fundamental level.

• Journal of Positioning, Navigation, and Timing
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• v.7 no.3
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• pp.183-188
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• 2018

The Global Navigation Satellite System (GNSS) signal gets delayed as it goes through the troposphere before reaching the GNSS antenna. Various tropospheric models are being used to correct the tropospheric delay. In this study, we compared effectiveness of two popular troposphere correction models: Global Pressure and Temperature (GPT) and Satellite-Based Augmentation System (SBAS). One-year data from a particular site was chosen as the test case. Tropospheric delays were computed using the GPT and SBAS models and compared with the International GNSS Service tropospheric product. The bias of SBAS model computations was 3.4 cm, which is four times lower than that of the GPT model. The cause of higher biases observed in the GPT model is the fact that one cannot get wet delays from the model. If SBAS-based wet delays are added to the hydrostatic delays computed using the GPT model, then the accuracy is similar to that of the full SBAS model. From this study, one can conclude that it is better to use the SBAS model than to use the GPT model in the standard code-pseudorange data processing.

• Asia pacific journal of information systems
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• v.14 no.1
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• pp.165-184
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• 2004

This paper focused on developing and empirically testing an EAM(Electronic-Store Acceptance Model), By basing upon Davis' TAM(Technology Acceptance Model) and reflecting the characteristics of EC(Electronic Commerce), the EAM was proposed. This EAM could be regarded as a revised and extended TAM in the EC area. The theoretical rationale of this model was as following: 1) Though Davis' TAM was proposed a powerful tool to explain and predict usage of Information Technology, nowadays, TAM variables(perceived usefulness and ease of use) are posited as key drivers of e-commerce acceptance. 2) In the e-commerce and e-business studies, trust has been emerging as a potentially important antecedent of IT adoption. A famous internet book store was chosen to empirically test the EAM. In order to evaluate reliability and validity of instrument, and validate the research model, SEM(Structured equation model) analysis was conducted. The results showed that perceived usefulness and trust significantly influenced e-Store Acceptance but perceived ease of use did not have significant influence on e-Store Acceptance.

• Journal of the Korea Society of Computer and Information
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• v.23 no.8
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• pp.59-66
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• 2018

In this paper we purposes to analyze the motivation of mobile payment adopters. In this study, with unified theory of acceptance and use of technology (UTAUT) model as the basis of research, we set up a structural equation model based on gender, age, experience and voluntary, collected data in the form of a questionnaire survey and analyzed drivers that affected mobile payers. In this study, The necessity of this paper is that the group of Korean students belongs to a special group with nearly 70,000 people. The penetration rate of mobile payment in China is 77%, ranking first in the world, but after the young people came to Korea. There are many obstacles and inconveniences when using mobile payment. We have proposed special subjects for special populations. the survey data were analyzed using SPSS22.0 and AMOS22.0 statistical software and the proposed model was modified. The results show that consumers' mobile payment is mainly motivated by social influence and performance expectancy. These results are of theoretical value and offer a new direction and implications to mobile payment developers. Besides, they also provide useful information and guidance for enterprises to aim at the market of Chinese oversea students in South Korea.

• Smart Structures and Systems
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• v.15 no.2
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• pp.259-281
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• 2015

In this study, a structural identification method is proposed to assess the integrity of gravity-type caisson structures by analyzing vibration features. To achieve the objective, the following approaches are implemented. Firstly, a simplified structural model with a few degrees-of-freedom (DOFs) is formulated to represent the gravity-type caisson structure that corresponds to the sensors' DOFs. Secondly, a structural identification algorithm based on the use of vibration characteristics of the limited DOFs is formulated to fine-tune stiffness and damping parameters of the structural model. Finally, experimental evaluation is performed on a lab-scaled gravity-type caisson structure in a 2-D wave flume. For three structural states including an undamaged reference, a water-level change case, and a foundation-damage case, their corresponding structural integrities are assessed by identifying structural parameters of the three states by fine-tuning frequency response functions, natural frequencies and damping factors.

• Journal of the Korean Society for Precision Engineering
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• v.16 no.2 s.95
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• pp.194-200
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• 1999

An elastomeric bushing is a device used in automotive suspension systems to cushion the force transmitted from the wheel to the frame of the vehicle. A bushing is an elastomeric hollow cylinder which is bonded to a solid metal shaft at its inner surface and a metal sleeve at its outer surface. For axial motion case, the relation between the force applied to the shaft and their relative displacement was considered. In this paper, the relation between the moment applied to the shaft and their relative deformation(angle of rotation) is considered for the torsional motion case. Numerical solutions of the boundary value problem represent the exact bushing response for use in the method for determining the moment relaxation function of the bushing. Solutions also allow for comparison between the exact moment-deformation behavior and that predicted the proposed model. It is shown that the predictions of the proposed moment-deformation relation are in very good agreement with the exact results.

• Journal of the Korean Operations Research and Management Science Society
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• v.29 no.4
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• pp.11-40
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• 2004

Organizations have attempted to develop Knowledge Management Systems for achieving competitive advantage by effectively managing organizational knowledge. However, if Knowledge Management Systems are not user-oriented, organizations may not attain desired goals. That is, it must be utilized and accepted by organizational members to be successful systems. This study proposes an extended Technology Acceptance Model and empirically validates it. For that purpose, a research model is set UP that consists of antecedent variables, perception moderators, and intention to use the system. Empirical data analysis found significant relationships among research variables, as suggested in research hypotheses. The results of the analysis indicated that perceived usefulness, ease of use, job relevance and information quality should be considered as important factors in designing Knowledge Management Systems. In addition, perceived value, incentive, affect, self-efficacy, and image were found to influence the perception of users in the usage situation.

• Journal of Information Display
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• v.8 no.4
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• pp.1-4
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• 2007

In the present study, we propose Monte Carlo simulation that takes into consideration the interface phenomena between liquid crystal and substrate. We use rigid model molecules of liquid crystal and substrate. Interface is generated using potential field that induces decomposition of molecules. We use hard spherocylinders as model liquid crystal molecules. Substrate is modeled as region composed of shorter spherocylinders. Our results show that there is a case in which nematic order is reinforced in the vicinity of rubbed substrate.

• Journal of Korean Society for Quality Management
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• v.43 no.3
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• pp.409-420
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• 2015

Purpose: This study is to estimate the life of elevator wire rope by using the accelerated degradation test with two accelerating variables of applied load and corrosion. Methods: Linear regression method is used to find the pseudo life of elevator wire rope at each combination of accelerating variables and the median life of elevator wire rope at use condition is estimated under the assumption that the life of elevator wire rope follows lognormal distribution. Results: The particular case study demonstrated that the results of the elevator wire life estimation by using the proposed method can provide the better solutions than existing methods. Conclusion: It can be economical to use accelerated degradation model for estimating the life of elevator wire rope.

• Spatial Information Research
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• v.10 no.4
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• pp.551-565
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• 2002

To carry out systematic groundwater assessment, exploration and management and to use these for protection of optimal groundwater yield, a data analysis and management system is required. Thus, the object of this research was to develop and apply software that integrates GIS and groundwater modeling: GISGAM (GIS for groundwater analysis and management system). The GIS program ArcView and the groundwater-modeling program MODFLOW were used for the GISGAM. The program components consist of a pre-processor, a processor, and a post-processor for groundwater modeling. In addition, GIS functions such as input, manipulation, analysis and output of data were embedded into the program. In applying the program to pilot area, topography, geology, soil, land use and well databases, and a groundwater flow model were constructed for the study area. This case study revealed the advantage and convenience of groundwater modeling using GIS capabilities. By integrating GIS and the groundwater model, the impact of changing values of hydrogeological constants on model results could be more easily evaluated.