• Magazine of the Korean Society of Agricultural Engineers
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• v.35 no.3
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• pp.130-139
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• 1993

In order to evaluate the long-term permeability performace of the geotextiles, for five different combination of geotextiles and soils the long-term column test method The results obtained are as follows; 1.The gradient range of the initial stage of the long-term permeability curves varied with respect to the soil types, while that of the final stage varied according to the interaction of the soil/geotextile system. 2.The time required for a given soil/geotextile system to reach a interactive stable stage was measured ahout 100 hours for the standard sand and 150 to 600 hours for the silty content soils, respectively. 3.There were no differences between the plain woven geotextile and the non-geotextile in the long-term permeability performance. 4.As the silt content increased, the long-term performance of the geotextiles decreased, and the limiting silt content was about 15%. 5.The thickness and area density of the geotextiles did not influence on the variation of the seepage quantities. 6.The ayerage slope and the transition time of the long-time flow curve were calculated. 7.In order to evaluate the mechanism of soil/geotextile system more perfectly, the gradient ratio test or the hydraulic conductivity test is required.

• Computers and Concrete
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• v.15 no.4
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• pp.687-707
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• 2015

A finite element computer code for short-term analysis of steel-concrete composite structures is extended to study long-term effects under service loads, in the present work. Long-term effects are important in engineering design because they influence stress and strain distribution of the structural system and therefore contribute to the increment of deflections in these structures. For creep analysis, a rheological model based on a Kelvin chain, with elements placed in series, was employed. The parameters of the Kelvin chain were obtained using Dirichlet series. Creep and shrinkage models, proposed by the CEB FIP 90, were used. The shear-lag phenomenon that takes place at the concrete slab is usually neglected or not properly taken into account in the formulation of beam-column finite elements. Therefore, in this work, a three-dimensional numerical model based on the assemblage of shell finite elements for representing the steel beam and the concrete slab is used. Stud shear connectors are represented for special beam-column elements to simulate the partial interaction at the slab-beam interface. The two-dimensional representation of the concrete slab permits to capture the non-uniform shear stress distribution in the horizontal plane of the slab due to shear-lag phenomenon. The model is validated with experimental results of two full-scale continuous composite beams previously studied by other authors. Results are given in terms of displacements, bending moments and cracking patterns in order to shown the influence of long-term effects in the structural response and also the potentiality of the present numerical code.

• The Journal of Korean Physical Therapy
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• v.34 no.6
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• pp.298-303
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• 2022

Purpose: The purpose of this study was to figure out how PAP (Post-Activation Potentiation) phenomenon affects short-term performance efficiently. Methods: This study was conducted with 18 Taekwondo athletes and 16 healthy adults. By using isokinetic dynamometer, two different intervention, TDP (Top-down program) and BUP (Bottom-up program), were performed to measure isokinetic parameter; (peak torque: PT, total work: TW, average power: AP, and average torque: AT) of knee extensor for intragroup, intergroup comparison and two-way ANOVA. Results: The Taekwondo athletes group showed statistically significant differences in all isokinetic parameters PT, TW, AP, and AT after TDP (p<0.05). However, in the healthy adult group, the difference in isokinetic parameters according to the exercise sequence was not statistically significant. (p>0.05). PT and TW at TDP were statistically significant (p<0.05) when the rate of change in TDP and BUP was compared and analyzed considering the difference in physical ability between the Taekwondo athlete group and the healthy adult group. However, AP and AT were not statistically significant. Finally, when examining the interaction between the two groups and two exercise sequence according to isokinetic parameters, only TW (p<0.05) showed a statistically significant interaction, while PT (P=0.099), AP (P=0.103), and AT (P=0.096) did not. This study suggests that short-term performance can be improved through the PAP phenomenon when TDP is applied to the Taekwondo group. Conclusion: According to our result, for Taekwondo athletes, if the goal is to improve short-term performance just before the main game, we suggest a training program through TDP.

• Journal of Information Technology Services
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• v.22 no.6
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• pp.103-114
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• 2023

In the post-pandemic era, colleges and students keep passion for learning online sine its unique advantages. This study explores how students' basic psychological needs drawn from self-determination theory, connect to interaction, and learning engagement in the context of online learning. While prior research explored students' intentions, digital interactions, and engagement in online learning, this study aims to come up with a united conceptual model drawing the three basic psychological needs and interaction and their effects on learning engagement. 178 response data collected through a questionnaire survey, were analyzed using PLS-SEM. Findings indicate that online learning interaction enhances intrinsic motivation, leading to higher learning engagement. Autonomy emerges as the most influential psychological need on learning engagement. This study integrates self-determination theory with online learning interactions and engagement and offers practical insights. Future research should examine long-term outcomes and diverse student populations.

• Journal of Families and Better Life
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• v.25 no.5
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• pp.167-183
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• 2007

The purpose of this study was to investigate the changes in infant-mother interactions and to measure infant-mother interaction, mutuality, and reciprocity at the 2nd and 6th postnatal monthperiods. Infant-mother interaction was assessed in the mornings, afternoons, and evenings in the 2nd and 6th postnatal months, by filming unstructured free play in the home and analyzing 28 of these infant-mother film recordingsusing two trained observers. This study can be summarized in five points. First, the separate frequency distribution of each category in MIIBR's maternal behavior was as follows: the frequencies of vocalization category, the kinesthetic exercise & physical contact category, the physical caregiving category, and theuse of play tool category. These all showed changes in the 6th postnatal month compared to the 2nd postnatal month. Second, the separate frequency distribution of each category in MIIBR's infant behavior was as follows: the frequencies of physical behavior category, the vocalization category, and the play behavior category. These also all showed changes in the 6th postnatal month compared to the 2nd postnatal month. Third, the mutuality and reciprocity of mother interaction decreased in the 2nd postnatal month compared to the 6th postnatal month. Fourth, mutuality and reciprocity in the infant interaction increased in 2nd postnatal month compared to the 6th postnatal month. Fifth, mutuality and reciprocity in the infant-mother interaction increased in 2nd postnatal month compared to the 6th postnatal month. In conclusion, it is evident that infant-mother interactions change over time. This study bears particular significance in setting a foundation for the theoretical basis of the interaction between infant and mother by observation.

• Journal of Institute of Control, Robotics and Systems
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• v.15 no.11
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• pp.1096-1101
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• 2009

In this paper, an embedded system has been designed for force control application to interact between a robot arm and a human operator. Force induced by the human operator is converted to the desired position information for the robot to follow. For smooth operations, the impedance force control algorithm is utilized to represent interaction between the robot and the human operator by filtering the force. To improve the performance of position control of the robot arm, a velocity term has been obtained and tested by several filters. A PD controller for position control has been implemented on an FPGA as well. Experimental studies are conducted with the ROBOKER to test the functionality of the designed hardware.

• Journal of Korean Library and Information Science Society
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• v.34 no.4
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• pp.1-20
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• 2003

Through analyzing papers on digital libraries and the contexts of usage of the term, ‘digital library’, this study investigates that the professional discourses about digital libraries regard them digital technologies. But digital libraries need to be recognized as socio-technical networks which are constructed by social interaction between heterogeneous elements. The study suggested that Social Informatics and a STIN(Socio-Technical Interaction Network) model should be applied to understand and analyze digital libraries as socio-technical networks.

• Journal of the Korean Society for Advanced Composite Structures
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• v.5 no.2
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• pp.27-32
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• 2014

Since the collapse of historical masonry structures in Europe in the late 1990's, the interests in understanding the long-term effect of masonry under sustained compressive stresses have increased. That requires combining the significance of time-dependent effects of creep with the effect of damage due to overstress to realize the evolution of cracks and then failure in masonry. Meanwhile, composite analysis of masonry columns was proven effective for realizing ultimate strength capacity of masonry column. In this study, a simplified mechanical model with step-by-step in time analysis was proposed to incorporate the interaction of damage and creep to estimate the maximum stress occurred in masonry. It was examined that the interaction of creep and damage in masonry can accelerate the failure of masonry.

• Proceedings of the KIEE Conference
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• 2005.07d
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• pp.2771-2773
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• 2005

In network human-robot interaction, human can access services of a robot system through the network The communication is done by interacting with the distributed sensors via voice, gestures or by using user network access device such as computer, PDA. The service organization and exploration is very important for this distributed system. In this paper we propose a new agent-based framework to integrate partners of this distributed system together and help users to explore the service effectively without complicated configuration. Our system consists of several robots. users and distributed sensors. These partners are connected in a decentralized but centralized control system using agent-based technology. Several experiments are conducted successfully using our framework The experiments show that this framework is good in term of increasing the availability of the system, reducing the time users and robots needs to connect to the network at the same time. The framework also provides some coordination methods for the human robot interaction system.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2001.04a
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• pp.120-127
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• 2001

Long term earthquake observations at different tunnel sites within a variety of alluvial soil deposits have demonstrated that a circular tunnel is liable to deform in such a way that its two diagonal diameters crossing each other expand and contract alternately. Based on this knowledge, the soil-tunnel interaction and isolation effect for this particular vibration mode is investigated. Interaction effect is considered with the condition of fixed tangential strain between the tunnel and the soil. Isolation effect embodied by covering up the tunnel with isolation materials is discussed as a possible measure for mitigating seismic damage to it. When Poisson`s ratio of isolation material decreases or the shear modulus ratios of the soil to isolation material become large, the isolation effect becomes bigger.