• Korean journal of communication and information
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• v.32
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• pp.369-405
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• 2006

The purpose of this paper is to examine the usefulness of the concept of political efficacy and political trust as a way of explaining the development of political participation in the young people under the new age of the Internet. From the survey in which 221 university students participated, there were several findings: first, overall political efficacy has a predominant effect on political participation in both offline and online; second, political trust has little impact on the political participation of the youth; third, there showed up two interaction effects between political efficacy and political trust for the online conventional and unconventional participation in politics. It is found that in high efficacy group people with low trust are most likely to participate, while in medium efficacy group people with high trust are most likely to participate. In low efficacy group, however, political trust didn't make any difference in political participation. There are more factors that may predict political participation, such as political interest, political knowledge, political ideology, and demographic variables. For future studies, it is necessary to examine the effect of political efficacy and political trust in combination with these other variables to explain political participation by offline and online.

• Journal of The Korean Association For Science Education
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• v.35 no.6
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• pp.1063-1074
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• 2015

In this study, we developed an analogy-generating strategy and applied this to a 7th grade science-gifted class. The types of analogies they generated, verbal interactions and analogy-generating patterns, and perceptions of five groups on the analogy-generating strategy were examined. The analyses of the results revealed that there was a higher proportion of the elaborated analogies in terms of quality generated by science-gifted students individually in the analogy-generating strategy than in general analogy-generating activity. After having small group activities, most small groups generated the elaborated analogies. The frequencies and percentages of verbal interactions of each sub-stage were found to be slightly different. Analogy-generating patterns in small groups were categorized into three types; selecting in-depth source, selecting inclusive source, and selecting surficial source. The elaborating patterns of mapping between a target concept and analogies were different among the types. Science-gifted students positively perceived in terms of its values and attitudes toward the analogy-generating strategy, and they responded that the analogy-generating strategy was helpful in generating more elaborated analogies and fostering creative thinking. Therefore the analogy-generating strategy is expected to generate positive impact on the creativity of science-gifted students.

• The Journal of Korean Academy of Prosthodontics
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• v.32 no.1
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• pp.148-169
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• 1994

The concept of biologic attachment of load-bearing implants has developed over the past decades as an alternative to the difficulties associated with long term implantation using mechanical fixation and bone cement. The choice of implant material is also as critical an element as site preparation or insertion procedure. The properties of implants that affect host tissue responses are not limited to chemical composition alone, but also include shape, surface characteristics, site of implantation, and mechanical interaction with host tissues. Initial mechanical interlocking prevents micromotion and may be a prerequisite for direct bone apposition. A hard tightening of screws does not necessarily mean a stronger fixation and final tightening of the fixtures is dependent on the experience of the operator. Removal torque is lower than insertion torque. The purpose of this study was to investigate differences in the removal torques at the bone-implant interface of polished and sandblasted Titanium. This experiment will give insight into important factors that must be considered when interpreting in vivo screwing forces on implants during the connection of the transmucosal abutments. We evaluated the significance of different surface textures by comparison of the withdrawal forces necessary for removal of otherwise identical rough and polished implants of Titanium and also evaluated interfacial response on the light microscopic level to implant surface. And the priority of the area of insertion on osseointegration were evaluated. 9 Titanium implants - among them, 3 were for the developmental - of either a smooth or rough surface finish were inserted in the dog mandible in the right side. 3 months later Kanon Torque Gauge was used to unscrew the implants. The results were as follows : 1. No significant difference was seen in the removal torque due to variation in surface treatment, 23 Ncm for the sandblasted and 23.33 Ncm for the polished surface (p>0.05). 2. Implants in the anterior (25 Ncm) mandible showed better resistance to unscrewing in comparison to ones in the posterior (18 Ncm) region (p<0.05). 3. Developmental fixtures (22 Ncm) had similar pullout strength to the control group (p>0.05).

• KOMUNHWA
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• no.68
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• pp.7-24
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• 2006

This article is the critical review of the methods and assumptions with which the Korean archaeologists have tried to approach to the Bronze age society. It was not until the 1980s' that there had been any attempt to define the relevant units for the study of past societies. Before the archaeological records of megalithic builders in the Bronze age began to be analyzed to find out the general traits of chiefdom society, Korean archaeologists had described the variations in the cultural, rather than the social, entities. From the 1990s' , some scholars have attempted to reconstruct the scale and organization of the social groups and explain the growth of polities in evolutionary view, analyzing the hierarchical distributions of settlement data. In the concluding remarks of the review, I would like to indicate the some problems in the conceptualization of the material culture patterning in the regional and/or inter-regional level. First, the conceptual problem which appeared when the Bronze archaeologists define the distribution of artifact assemblages, composed of the specific artifact traits , beyond the instrumental categories that are efficient for the establishments of regional chronologies. It is evidently erroneous conceptualization that we define the artifact assemblages as the socio-cultual entities which came into being in specific time and place, geographically expanded, and finally disappeared based on the view of essentialism. Second, the interpretative problems about wide distributions of certain bronze artifacts must be indicated. I would like to suggest that the wide distributions of the specific bronze dagger or mirror types should be explained not by the cultural area concept related to the ethnicity assumptions, but by the world system or the inter-regional interaction models.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.48 no.2
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• pp.135-146
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• 2020

To define an interface in a conventional level-set method, an analytical function must be revealed for an interfacial geometry. However, it is not always possible to define a functional form of level sets when interfaces become complex in a Cartesian coordinate system. To overcome this difficulty, we have developed a new level-set formalism that discriminates the interior from the exterior of a CAD modeled interface by parameterizing the stereolithography (STL) file format. The work outlined here confirms the accuracy and scalability of the hydrodynamic reactive solver that utilizes the new level set concept through a series of tests. In particular, the complex interaction between shock and geometrical confinements towards deflagration-to-detonation transition is numerically investigated. Also, a process of flame spreading and damages caused by point source detonation in a real-sized plant facility have been simulated to confirm the validity of the new method built for reactive hydrodynamic simulation in any complex three-dimensional geometries.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.13 no.2
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• pp.51-59
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• 1993

This paper develops practical and realistic reliability models and methods for the evaluation of system-reliability and system reliability-based rating of various types of box-girder bridge superstructures. The strength limit state model for box-girder bridges suggested in the paper are based on not only the basic flexural strength but also the strength interaction equations which simultaneously take into account flexure, shear and torsion. And the system reliability problem of box-girder superstructure is formulated as parallel-series models obtained from the FMA(Failure Mode Approach) based on major failure mechanisms or critical failure states of each girder. In the paper, an improved IST(Importance Sampling Technique) simulation algorithm is used for the system reliability analysis of the proposed models. This paper proposes a practical but rational approach for the evaluation of capacity rating in terms of the equivalent system-capacity rating corresponding to the estimated system-reliability index which is derived based on the concept of the equivalent FOSM(First Order Second Moment) form of system reliability index. The results of the reliability evaluation and rating of existing bridges indicate that the reserved reliability and capacity rating at system level are significantly different from those of element reliability or conventional methods especially in the case of highly redundant box-girder bridges.

• Education of Primary School Mathematics
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• v.13 no.2
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• pp.85-97
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• 2010

The purpose of this study is to develop a teaching program in consideration of the geometrical thinking levels of students to make a contribution to teaching figures effectively. To do this, we checked the geometrical thinking levels of fourth-graders, developed a teaching program based on van Hiele's theory, and investigated its effect on their geometrical thinking levels. The teaching program based on van Hiele's theory put emphasis on group member interaction and specific activities through offering various geometrical experiences. It contributed to actualizing activity-centered, student-oriented, inquiry-oriented and inductive instruction instead of sticking to expository, teacher-led and deductive instruction. And it consequently served to improving their geometrical thinking levels, even though some students didn't show any improvement and one student was rather degraded in that regard - but in the former case they made partial progress though there was little marked improvement, and in the latter case she needs to be considered in relation to her affective aspects above all. The findings of the study suggest that individual variances in thinking level should be recognized by teachers. Students who are at a lower level should be given easier tasks, and more challenging tasks should be assigned to those who are at an intermediate level in order for them to have a positive self-concept about mathematics learning and ultimately to foster their thinking levels.

• Interaction and multiscale mechanics
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• v.2 no.1
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• pp.69-89
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• 2009

Reinforced and prestressed concrete (RC and PC) thin walls are crucial to the safety and serviceability of structures subjected to shear. The shear strengths of elements in walls depend strongly on the softening of concrete struts in the principal compression direction due to the principal tension in the perpendicular direction. The past three decades have seen a rapid development of knowledge in shear of reinforced concrete structures. Various rational models have been proposed that are based on the smeared-crack concept and can satisfy Navier's three principles of mechanics of materials (i.e., stress equilibrium, strain compatibility and constitutive laws). The Cyclic Softened Membrane Model (CSMM) is one such rational model developed at the University of Houston, which is being efficiently used to predict the behavior of RC/PC structures critical in shear. CSMM for RC has already been implemented into finite element framework of OpenSees (Fenves 2005) to come up with a finite element program called Simulation of Reinforced Concrete Structures (SRCS) (Zhong 2005, Mo et al. 2008). CSMM for PC is being currently implemented into SRCS to make the program applicable to reinforced as well as prestressed concrete. The generalized program is called Simulation of Concrete Structures (SCS). In this paper, the CSMM for RC/PC in material scale is first introduced. Basically, the constitutive relationships of the materials, including uniaxial constitutive relationship of concrete, uniaxial constitutive relationships of reinforcements embedded in concrete and constitutive relationship of concrete in shear, are determined by testing RC/PC full-scale panels in a Universal Panel Tester available at the University of Houston. The formulation in element scale is then derived, including equilibrium and compatibility equations, relationship between biaxial strains and uniaxial strains, material stiffness matrix and RC plane stress element. Finally the formulated results with RC/PC plane stress elements are implemented in structure scale into a finite element program based on the framework of OpenSees to predict the structural behavior of RC/PC thin-walled structures subjected to earthquake-type loading. The accuracy of the multiscale modeling technique is validated by comparing the simulated responses of RC shear walls subjected to reversed cyclic loading and shake table excitations with test data. The response of a post tensioned precast column under reversed cyclic loads has also been simulated to check the accuracy of SCS which is currently under development. This multiscale modeling technique greatly improves the simulation capability of RC thin-walled structures available to researchers and engineers.

• Journal of Technology Innovation
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• v.21 no.1
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• pp.303-330
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• 2013

Korea has started new value creation which is the post catch-up innovation system from the catch-up innovation. Post catch-up innovation system is becoming the main R&D issue for Korea and is needed for the new concept of R&D management and planning frame. This study posed questionnaires : how to promote the knowledge creation in technology planning and what the role of organizational learning in the technology planning is. This paper suggests the relationship of success factors of knowledge creation in technology planning which is organized and operated by experts with different background. Based on the prior research on organizational learning, communications and collaborative interactions, four hypotheses that factors of knowledge creation in technology planning have positive relationship with organizational learning are extracted. This study adopts Structural Equation Modeling(SEM) to analyze the relationship between organizational learning and successful technology planning. The approach based on organizational learning and interaction will be useful for constructing the planning framework in the era of post catch-up innovation. This paper, therefore, suggests the possibility of new theoretical development and new research agenda.

• Journal of Science and Technology Studies
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• v.18 no.1
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• pp.177-217
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• 2018

This study examines the case of living lab applied in the R&D initiatives for solving societal problems and challenges. It discusses how to use the living lab in national R&D projects. The analyzed cases are 'Develop portable fundus camera for eye disease screening test to resolve health inequalities' and 'Auto-sensing integrated system development in rural pedestrian crosswalk'. As a result of the analysis, both cases were designed as a user participatory R&D structure by utilizing living lab. In other words, living lab has operated as a system that evolves technology-products-services into an infrastructure. It can realize final demand specification, product, service improvement and demonstration through continuous interaction of end users. As a result of the case analysis, the following policy tasks can be derived. First, living lab is a new concept and it is in the early stage of implementation in Korea. Therefore, it is necessary to monitor and evaluate living lab experiments and build suitable models for Korean society by sharing cases and achievements. Second, the strategic niche management are necessary for the introduction of living lab. Third, living lab can be used as a tool to transform the existing technology acquisition centered innovation policy to the policy for customer needs and problem solving. Fourth, there is a need for flexibility and adaptability in strategy and system to correct errors that appear in the living lab processes.