• Proceedings of the Materials Research Society of Korea Conference
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• 2001.11a
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• pp.61-61
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• 2001

• Korean Journal of Childcare and Education
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• v.9 no.1
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• pp.175-200
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• 2013

This study focused on the relationships among teachers'playfulness, teachers'positive play beliefs, teaching efficacy on play and teacher's strategies of problem behavior guidance, and especially the mediating effects of teaching efficacy on children's play. Subjects were 151 early childhood teachers in Seoul and Chungcheungnam-do. The collected data were analyzed using simple regression, hierarchical multiple regression and the Sobel test. The main results of this study were as follows. First, teachers' playfulness and teachers'positive play beliefs had a positive influence on their proactive, positive reactive strategies of problem behaviors. On the other hand, teachers' positive play beliefs had a negative influence on their negative reactive strategies of problem behaviors. Second, teachers' playfulness and teachers'positive play beliefs had a positive influence on their teaching efficacy on play. Finally, the effects of teachers' playfulness on their proactive, positive reactive strategies of problem behaviors of preschoolers were totally mediated by their teaching efficacy on play.

• Journal of Institute of Control, Robotics and Systems
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• v.8 no.11
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• pp.954-962
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• 2002

In a park or street, we can see many people jogging or walking with their dogs tracking their masters. In this study, an entertainment robot that imitates a dog's behavior is created. The robot's task is tracking a moving target that is recognized as the master. In order to design the robot, the ecological approach. in which the robot's goals and surroundings heavily influence its design, is used. A three-wheel type locomotion system is designed as the robot's physical structure which can follow a human jogging in outdoor space like a park. A sensor system which can detect the position of a master for the robot in the outdoor space, is developed. This sensor system consists of a signal transmitter which is at the hand of a master and some sensors which are mounted on the robot. The transmitter emits RF(radio frequency) and ultrasonic signals and the sensors detect the direction and distance from the robot to the transmitter by using the received signals. For the control architecture of the robot, a purely reactive behavior-based method is used in order to increase speed of response. The developed robot is evaluated through experiments conducted in indoor and outdoor environments.

• Korean Journal of Materials Research
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• v.3 no.2
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• pp.140-144
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• 1993

Abstract To modify brittleness among the properties of thermosetting epoxy resin, a reactive additive. succinonitrile(SN) was introduced to Diglycidyl ether of bisphenol A(DGEBA)-4, 4'-methylene dianiline (MDA) system. Fracture behavior was microscopically studied during breaking of composite materials. As a result, post debond friction energy was the most significant for breaking the composite having glass fibres, pull-out energy was the next significant and debonding energy was the last. It was observed that shear stress between glass fibre and epoxy matrix was main factor for fracture behavior. Reactive additive, SN made shear stress deteriorated.

• Advances in robotics research
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• v.1 no.1
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• pp.101-126
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• 2014

In this article we present modular neural control for a leg-wheel hybrid robot consisting of three legs with omnidirectional wheels. This neural control has four main modules having their functional origin in biological neural systems. A minimal recurrent control (MRC) module is for sensory signal processing and state memorization. Its outputs drive two front wheels while the rear wheel is controlled through a velocity regulating network (VRN) module. In parallel, a neural oscillator network module serves as a central pattern generator (CPG) controls leg movements for sidestepping. Stepping directions are achieved by a phase switching network (PSN) module. The combination of these modules generates various locomotion patterns and a reactive obstacle avoidance behavior. The behavior is driven by sensor inputs, to which additional neural preprocessing networks are applied. The complete neural circuitry is developed and tested using a physics simulation environment. This study verifies that the neural modules can serve a general purpose regardless of the robot's specific embodiment. We also believe that our neural modules can be important components for locomotion generation in other complex robotic systems or they can serve as useful modules for other module-based neural control applications.

• Structural Engineering and Mechanics
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• v.84 no.6
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• pp.783-798
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• 2022

This study attempts to investigate the impact of thickness stretching and nonlinear hygro-thermo-mechanical loading on the bending behavior of FG beams. Young's modulus, thermal expansion, and moisture concentration coefficients vary gradually and continuously according to a power-law distribution in terms of the volume fractions of the constituent materials. In addition, the interaction between the thermal, mechanical, and moisture loads is involved in the governing equilibrium equations. Using the present developed analytical model and Navier's solution technique, the numerical results of non-dimensional stresses and displacements are compared with those obtained by other 3D theories. Furthermore, the present analytical model is appropriate for investigating the static bending of FG beams exposed to intense hygro-thermo-mechanical loading used for special technical applications in aerospace, automobile, and civil engineering constructions.

• Journal of the Korean GEO-environmental Society
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• v.15 no.1
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• pp.13-23
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• 2014

Geotechnical evaluation on the reactive drain pile which can achieve simultaneously both the soft ground improvement and the remediation of contaminated pore water in reclamation site was performed. Applicability of steel-making slag used as a inside reactive material was confirmed. To investigate the consolidation characteristics of the soft ground improved by reactive drain pile, testing devices to form and install the reactive drain pile were developed and laboratory tests were performed according to the existence of outside sand drain and the length of impermeable barrier. Test results showed that the consolidation time was decreased as the shortening of impermeable barrier. However, the effect of outside sand drain on consolidation time was dominant compared with the length of impermeable barrier.

• Journal of Korean society of Dental Hygiene
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• v.20 no.3
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• pp.303-312
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• 2020

Objectives: The purpose of this study was to investigate the relationship between periodontal disease, number of remaining teeth with high-sensitivity C-Reactive protein in Korean adults aged 40 and older. Methods: The study used the Sixth Korea National Health and Nutrition Examination Survey (KNHANES VI-3), 2015. The study sample consisted of 3,883 aged 40 years or older who had completed the health survey and the health examination. Logistic regression analyses were performed to examine the odds ratios of high-sensitivity C-Reactive protein by periodontal disease and number of remaining teeth, adjusting for demographic characteristics, chronic diseases and oral health behavior-related variables. Results: When the demographic and chronic diseases were adjusted, the risk of high-sensitivity C-Reactive protein (hs-CRP) average 1.23 mg/L or higher was 1.36 times higher in patients with periodontal disease between the ages of 40 and 49, but it was not significant (OR=1.36; 95% CI=0.82-2.23). In addition, in the group of 0~23 remaining teeth aged 40~49 years, the risk of higher than the average 1.23 mg/L of high-sensitivity C-Reactive protein was 2.03 times higher (OR=2.03; 95% CI=1.10-3.74), and 1.49 times higher in 60~69 years (OR=1.07; 95% CI=1.04-2.76). Conclusions: This study found that periodontal disease and tooth loss in Korean adults aged 40 and older was significantly associated with high-sensitivity C-reactive protein.

• Proceedings of the Korean Society of Dyers and Finishers Conference
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• 2008.04a
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• pp.172-174
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• 2008

The study has attempted to compare the behavior of reactive, disperse and acid dyes when wastewater from these three kinds of typical dyestuffs were treated by chemical coagulation and NF membrane in pilot scale. Disperse dyeing wastewater showed the tendency of easier removal in TOC and COD and especially in color. This is probably due to low water-solubility of disperse dyes compared with reactive and acid dyes and is a positive result in terms of water reuse. Bio-kinetic constants, ${\mu}$max, $K_s$ of reactive, disperse and acid dyes were obtained, implying that their biodegradability are not significantly different.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.198.2-198.2
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• 2016

Reactive oxygen and nitrogen species (RONS) can be generated by using non-thermal atmospheric pressure plasma jet which have profound biomedical applications [1, 2]. In this work, reactive oxygen species like hydroxyl radical (OH) are generated by using non-thermal direct plasma jet above water surface using Ar gas and their properties have been studied using ultraviolet absorption spectroscopy. OH radicals are found to be generated simultaneously with the discharge current with concentration of $2.7{\times}1015/cm3$ at 7mm above water surface while their persistence time have been measured to be $2.8{\mu}S$. In addition, it has been shown that plasma initiated ultraviolets play a major role to generate RONS inside water. Further works are going on to measure the temporal behavior of OH and $O2^*-$.