• 대한원격탐사학회지
• /
• 제25권3호
• /
• pp.243-253
• /
• 2009

For the last 14 years, space-borne satellite SAR system such as RADARSAT-1, ERS-2, and ENVISAT ASAR have provided a continuous observation over the ocean. However, the data acquired from those systems were limited to C-band frequency until the advent of the first spacebome German X-band SAR system TerraSAR-X in 2007. Korea is also planning to launch the nation's first X-band SAR satellite (KOMPSAT-5) in 2010. It is timely and necessary to develop X-band models for estimating geophysical parameters from these X-band SAR systems. In this study, X-band wind retrieval model was investigated and developed based on numerical ocean scattering model (radar backscattering model and hydrodynamic interaction model). Although these models have not yet been tested and validated for broad ranges of wind conditions, the estimated wind speeds from TerraSAR-X data show generally good agreement with in-situ measurements.

• 한국철도학회:학술대회논문집
• /
• 한국철도학회 1999년도 추계학술대회 논문집
• /
• pp.566-573
• /
• 1999

This paper is the result of sensitivity analysis of derailment with respect to the selected suspension elements for the rail vehicle. Derailment phenominon has been explained by the derailment quotient. Thus, the sensitivity of derailment is suggested by a response surface model(RSM) which is a functional relationship between derailment quotient and characteristics of suspension elements. To summarize generation of RSM, we can introduce the procedure of sensitivity analysis as follows. First, to form a RSM, a experiment is performed by a dynamic analysis code, VAMPIRE according to a kind of the design of experiments(DOE). Second, RSM is constructed to a 1$\^$st/ order polynomial and then main effect fators are screened through the stepwise regression. Finally, we can see the sensitivity level through the RSM which only consists of the main effect factors and is expressed by the liner, interaction and quadratic effect terms.

• 한국정보시스템학회지:정보시스템연구
• /
• 제19권3호
• /
• pp.75-103
• /
• 2010

This study analyzes a model appling value in the mobile learning. We investigate the interaction, ease of use, hedonic value, and utilitarian value considering importance factors in the mobile learning, and the customer values are found to influence the customer satisfaction. We analysis a relationship between these factors and the customer satisfaction, and the relationship between the customer satisfaction and the loyalty. Finally, we research difference among gender of the satisfaction on the mobile learning. To fulfill this purpose, the research model was designed from literature review, and the structural equation modeling technique was used to evaluate hypotheses. The major results of this study are as follows. First, the ease of use, hedonic value, and utilitarian value positively influenced the satisfaction, and the satisfaction had positive influences on the customer loyalty. But the interaction didn't have positive influence on the satisfaction. Second, gender difference was found for some path coefficient. Male user's interaction and ease of use has effect on the satisfaction, and Female user's hedonic value and utilitarian value have influenced the satisfaction. When it consider the market share or the growth potential of the mobile learning industry, the results of this study will provide the useful information to manage mobile learning.

• 대한기계학회논문집A
• /
• 제20권7호
• /
• pp.2108-2117
• /
• 1996

The purpose of this paper is to investigate the influence of the exciter attached for the measurement of natural frequencies when extracting the frequency response functions of the test structure in experimental modal analysis. The procedure is first to model the attached exciter as an additional degree of freedom system and next to verify the suggested model by experimentally extracting the natural frequencies of the test structure with various values of exciter mass, stinger stiffness and attachment position of the exciter on the test structure. It is concluded that as additional degree of freedom system which includes the natural frequency of the exciter itself and axial stiffness of stinger should be considered to quantatively define the coupling effects of structure-exciter interaction on the measured natural frequencies. It is not the mass of the exciter itself but the coupling effect of the additional degree of freedom mass-spring system consisting of exciter body and armature coil that characterizes the natural frequency deviation. Therefore, when the natural frequency of this additional mass-spring system is outside of the test frequency range, the coupling effect of structure-exciter interaction can be minimized.

• 한국초등과학교육학회지:초등과학교육
• /
• 제28권4호
• /
• pp.519-528
• /
• 2009

The purpose of this study was to investigate the effect of social interaction on metacognition, learning motive and academic achievement in elementary science learning. The science lessons emphasizing social interactions that is applied to this study was comprised of 5 stages, 'introduction', 'inquiry activity', 'small group emergent activity', 'large group emergent activity', 'conclusion and assessment'. The results of this study were as follows: First, applying the learning model emphasizing social interaction to the experimental group led to a significant difference between the result of the pre- and post-test, regarding metacognition, especifically those of declarative knowledge. And meaningful difference was drawn from the results of all elements in the lower category of regulation of cognition between the experimental and comparison group. Second, a significant difference was found between the pre- and post-test regarding learning motive, especially those of attention, relation, and self-confidence. Third, after applying the learning model emphasizing social interaction to the science classes of the experimental group, students' academic achievement improved significantly in the post-test, compared to the results of pre-test.

• Interaction and multiscale mechanics
• /
• 제4권1호
• /
• pp.65-83
• /
• 2011

In this study, two extreme cases of compatibility of the horizontal displacements between the foundation and soil are considered, for which the pressure and settlements of the isolated footings and member end actions in structural elements are obtained using the three dimensional models and numerical experiments. The first case considered is complete slip between foundation and soil, termed as the un-coupled analysis. In the second case of analysis, termed as the coupled analysis, complete welding is assumed of joints between the foundation and soil elements. The model and the corresponding computer program developed simulate these two extreme states of compatibility giving insight into the variation of horizontal displacements and horizontal stresses and their intricacies, for evaluation of the influence of using the interface elements in soil-structure interaction analysis of three dimensional multiscale structures supported by isolated footings.

• 한국자동차공학회논문집
• /
• 제22권2호
• /
• pp.182-189
• /
• 2014

This paper proposes a decoupler design method to reduce interaction between exhaust gas recirculation (EGR) and variable geometry turbocharger (VGT) systems in passenger car diesel engines. The EGR valve and VGT vane are respectively used to control air-to-fuel ratio (AFR) of exhaust gas and intake pressure. A plant model for EGR and VGT systems is defined by a first order transfer function plus time-delay model, and the loop interaction between these systems is analyzed using a relative normalized gain array (RNGA) method. In order to deal with the loop interaction, a design method for simplified decoupler is applied to this study. Feedback control algorithms for AFR and intake pressure are composed of a compensator using PID control method and a prefilter. The proposed decoupler is evaluated through engine experiment, and the results successfully showed that the loop interaction between EGR and VGT systems can be reduced by using the proposed decoupler. Furthermore, it presents stable performance even off from the designed operating point.

• 아동학회지
• /
• 제33권6호
• /
• pp.109-131
• /
• 2012

The purpose of this study was to investigate the effects of the home literacy environment, mother's literacy belief and parenting efficacy in terms of the interaction which occurs during reading picture books between mothers and preschoolers. Questionnaires from 378 5-year-olds' mothers in Seoul and Kyunggi province were analysed. The findings from the validated structural equation model constructed with these variables were as follows. First, the home literacy environment, the mother's literacy beliefs and the mother's general parenting efficacy affected the quantity, and the quality of interaction whilst reading books with preschoolers. Second, the mother's efficacy in education and communication had a direct impact on the quantity of the interaction during reading books through the mediation of the home literacy environment, and had an indirect effect on the quality of the interaction whilst reading books, respectively. Third, the mother's efficacy in communication directly accounted for the quality of the interaction which occurs whilst reading books with children.

• Geomechanics and Engineering
• /
• 제16권3호
• /
• pp.309-320
• /
• 2018

In this paper, a numerical study using finite element method with considering soil-structure interaction was conducted to investigate the stress and deformation behavior of a sheet pile wall structure. In numerical model, one of the nonlinear elastic material constitutive models, Duncan-Chang E-v model, is used for describing soil behavior. The hard contact constitutive model is used for simulating the behavior of interface between the sheet pile wall and soil. The construction process of excavation and backfill is simulated by the way of step loading. We also compare the present numerical method with the in-situ test results for verifying the numerical methods. The numerical analysis showed that the soil excavation in the lock chamber has a huge effect on the wall deflection and stress, pile deflection, and anchor force. With the increase of distance between anchored bars, the maximum wall deflection and anchor force increase, while the maximum wall stress decreases. At a low elevation of anchored bar, the maximum wall bending moment decreases, but the maximum wall deflection, pile deflection, and anchor force both increase. The construction procedure with first excavation and then backfill is quite favorable for decreasing pile deflection, wall deflection and stress, and anchor forces.

• Journal of Power Electronics
• /
• 제11권4호
• /
• pp.439-448
• /
• 2011

In this work the Multi-Domain model of an electric vehicle is developed. The electric domain model consists on the traction drive and allows including faults associated with stator winding. The thermal model is based on a spatial discretization. It receives the power dissipated in the electric domain, it interacts with the environment and provides the temperature distribution in the induction motor. The mechanical model is a half vehicle model. Given that all models are obtained using the same approach (Bond Graph) their integration becomes straightforward. This complete model allows simulating the whole system dynamics and the analysis of electrical/mechanical/thermal interaction. First, experimental results are aimed to validate the proposed model. Then, simulation results illustrate the interaction between the different domains and highlight the capability of including faults.