• Journal of the Korean Chemical Society
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• v.40 no.6
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• pp.420-426
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• 1996

The critical micelle concentration(CMC) and the counterion binding $constant(\beta)$ at the CMC of the mixtures of Sodium dodecylsulfate(SDS) with Sodium dodecylbenzenesulfonate(DBS) in aqueous solutions have been determined from the concentration dependence of electrical conductance at several temperatures from $15^{\circ}C$ to $35^{\circ}C.$ Thermodynamic parameters(${\Delta}C_p,\;{\Delta}G_m^{\circ},\;{\Delta}H_m^{\circ}$ 및 ${\Delta}S_m^{\circ}$ and ${\Delta}C_p$), associated with the micelle formation of SDS/DBS mixtures, have been estimated from the temperature dependence of CMC and $\beta$ values. The measured values of ${\Delta}G_m^{\circ}\;and\;{\Delta}C_p$ are negative but the values of ${\Delta}S_m/^{\circ}$ are positive in the whole measured temperature region. The significance of these thermodynamic parameters and their relation to the theory of the micelle formation of SDS/DBS mixtures have been also considered.

• Nuclear Engineering and Technology
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• v.14 no.3
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• pp.138-147
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• 1982

A theoretical basis for analysis of plutonium-hearing fuel in a thermal nuclear power reactor has been established. The analysis of UO$_2$-PuO$_2$ fueled, light water moderated uniform lattice experiments has been performed. A unit cell program, KARATE, which is based on the theoretical models of GAM and THERMOS with some modifications, has been developed to generate a few-group cross-sections. These cross-sections are subsequently used in the diffusion theory code, KIDD, to compare the calculated values of the effective multiplication factor with the measured. The average value of the effective multiplication factor for 41 selected critical experiments is estimated to be 0.9997 with standard deviation of 0.43%. This illustrates the fact that KARATE/KIDD system can be effectively used for the analysis of uniform lattices of UO$_2$-PuO$_2$fuels.

• Journal of the Society of Naval Architects of Korea
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• v.35 no.1
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• pp.72-79
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• 1998

Static deformation theory of elastoplastic structures can be applied only if the magnitude of loading is less than the plastic collapse force $F_c$. However, with impact or explosive blast loading, the structure can be subjected to an intense but short-duration force pulse that exceeds the plastic collapse force and initiates structural collapse. In this paper, the dynamic response of a rigid-perfectly plastic cantilever subject to intense impact loading is examined in terms of the plastic collapse force. When a step loading is applied, the motion of the beam is calculated and analyzed through the non-dimensionalization of variables. It is concluded that the motion of a beam can be characterized as a function of the nondimensionalized force parameter, $f{\equiv}F/F_c$, where $F_c$ represents the critical force for plastic collapse. This result is used to the analysis of the beam motion subject to rectangular force pulse.

• Journal of the Korea Society of Computer and Information
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• v.15 no.12
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• pp.237-245
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• 2010

Korea Communications Commission (KCC) has been providing the pilot service of URC(Ubiquitous Robot Companion), which is a network-based personal robot, to 1000 Korean households since 2006 to define potential users' needs and adoption behaviors. Personal innovativeness might play a critical role in adoption of URC services by users because much sophisticated and convergence technologies are incorporated into URC services. Also, defining not only perceived beliefs about URC services but also expected beliefs about them are very crucial to reduce disconfirmation between users' perception and expectation of URC services. From this point of view, this paper aimed to examine robot users' adoption behavior by considering constructs such as personal innovativeness, usefulness (perceived usefulness - expected usefulness, P-E), user attitude, and intention to use. The findings reveal that personal innovativeness is negatively related to usefulness (P-E) whereas usefulness (P-E) influences significantly and positively on user attitude. It is also shown that usefulness (P-E) and user attitude have strong positive effects on intention to use.

• Journal of the Korean Geotechnical Society
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• v.18 no.5
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• pp.271-280
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• 2002

A probabilistic approach to identify the effects of uncertainties of soil strength parameters on searching a critical slip surface with the lowest reliability is introduced. In general construction field, it is impossible for the engineer to always gather a variety of statistical information of soil strength parameters for which lots of laboratory and in-situ soil testing are required and to use it with enough statistical knowledge. Thus, in order that the engineer may easily understand the probabilistic concept for the slope stability analysis, this study proposes a combined procedure to incorporate the engineering probabilistic tools into the existing deterministic slope stability analysis methods. Using UTEXAS 3, a slope stability analysis computer program developed by U.S. Army Corps of Engineers (U.S. COE), this study provides the results of this probabilistic slope stability analysis in terms of probability of failure or reliability index. This probabilistic method f3r slope stability analysis appears to yield more comprehensive results of slope reliability than does existing deterministic methods with safety factors alone.

• Korean Journal of Health Education and Promotion
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• v.25 no.1
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• pp.83-104
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• 2008

Objectives: Community-Based Participatory Research (CBPR) is a kind of health promotion approach to increase social cohesion and sense of community, which has built the collaborated partnership in all phases. This has the co-ownership of research objectives and knowledges produced by residents, and the outcome was taken to enhance community empowerment. This study performed to embody CBPR, which had regulated collective health status approached by social epidemiology. Methods: Reference review had been exercised focused on CBPR books and papers published since 1990. Our interests were aimed at its paradigm and methodological issues. Particularly, we problematized its feasibility in the social and behavioral foundations of pubic health. Results: According to the review, CBPR shared critical understanding and decision-making related to their community development including health status. Therefore, it was strength-based approach in spite of scientific dichotomy. CBPR created social cohesion and community empowerment with all participants, because it sublated contradiction between subjectivism and objectivism. Conclusions: The success of CBPR needs what we so called trust, democracy, collaboration, devotion, and consensus of equity. Despite these factors, CBPR may be a methodological transition to prepare some intervention of health inequality. This is because it does emphasize a mixture of theory and praxis to manage vulnerable people in community.

• Journal of Korean Elementary Science Education
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• v.28 no.2
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• pp.213-228
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• 2009

The purpose of this study was to examine whether the new introduction of elementary science experiment specialist is appropriate under the current situation of serious emphasis of the importance in science experiments in elementary science in Korea. For this study, the survey items were developed twice through the preliminary study. The results show that most elementary teachers consider the importance of experiment in elementary science and the critical role of science experiments to increase students' curiosity and scientific understanding. About 80% of the teachers stressed the professionalism in elementary science. Although 65% of the teachers believed their having basic professionalism, 53% of them appealed the difficulty in teaching science experiments to students. Nevertheless, 67.5% of the teachers opposed to the idea of teaching elementary science in separation between experiment and theory in science, and only 8% of them agreed the idea of induction or adoption of the college graduates majoring in science and engineering, or holding the secondary teacher's certificate. Further, over 60% of the teachers responded no necessity of inducing the new policy of elementary science specialist. Many numbers of teachers revealed their serious worries about the new policy because of their past experience to suffer from the side effects of inducing the teachers with secondary teacher certificate to the elementary school. In particular, they also made a proposal to make a good use of the current system of exclusive elementary science teacher in Korea. The educational implication and suggestions for policy making were discussed.

• Steel and Composite Structures
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• v.25 no.1
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• pp.105-116
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• 2017

This paper presents the dynamic stability study of laminated composite plates with different force combinations and aspect ratios. Optimum non-diverging stacking is obtained for certain loading combination and aspect ratio. In addition, the stability force is maximized for a definite operating frequency. A dynamic version of the principle of virtual work for laminated composites is used to obtain force-frequency relation. Since dynamic stiffness governs the divergence or flutter, an efficient optimization method is necessary for the response functional and the relevant constraints. In this way, a model based on the ant colony optimization (ACO) algorithm is proposed to search for the proper stacking. The ACO algorithm is used since it treats with large number of dynamic stability parameters. Governing equations are formulated using classic laminate theory (CLT) and von-Karman plate technique. Load-frequency relations are explicitly obtained for fundamental and secondary flutter modes of simply supported composite plate with arbitrary aspect ratio, stacking and boundary load, which are used in optimization process. Obtained results are compared with the finite element method results for validity and accuracy convince. Results revealed that the optimum stacking with stable dynamic response and maximum critical load is in angle-ply mode with almost near-unidirectional fiber orientations for fundamental flutter mode. In addition, short plates behave better than long plates in combined axial-shear load case regarding stable oscillation. The interaction of uniaxial and shear forces intensifies the instability in long plates than short ones which needs low-angle layup orientations to provide required dynamic stiffness. However, a combination of angle-ply and cross-ply stacking with a near-square aspect ratio is appropriate for the composite plate regarding secondary flutter mode.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.22 no.10
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• pp.41-48
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• 2008

This paper proposes a three-phase Z-source dynamic voltage restorer (Z-DVR) to mitigate the voltage sag for the critical loads. The proposed system is composed of passive filter and Z-source topology inverter. As an ESS(Energy Storage System) of the proposed system is employed the Proton Exchange Membrane Fuel Cells (PEMFC). To calculate and control the harmonics and compensation voltage, $i_{d}-i_{q}$ theory in dq rotating reference frame and PI controller are used. In case that three-phase voltage sags occurred, a PSIM simulation was done for the performance comparison of the conventional method employed battery stacks and proposed method. As a result, considering the voltage compensation performance, each method was nearly similar. Also, the compensation performance and the %THD(%Total Harmonic Distortion) result under the various source voltage conditions (sag or swell) were presented and discussed to show the performance of the proposed system.

• Journal of Elementary Mathematics Education in Korea
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• v.15 no.3
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• pp.487-507
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• 2011

Despite the recent increased attention to mathematics teacher education there have been lack of empirical studies on how to teach teachers. A study of mathematics instruction for prospective teachers can be conducted either by a teacher educator's critical reflection on her teaching or by observation of others' teaching practices. This paper was from the author's observation of a mathematics instruction course for future elementary teachers at the University of California at Irvine. As such this paper described in detail how the course was implemented throughout the quarter and drew implications for a teacher preparation program in Korea. As the course had a specific purpose of promoting future teachers' expertise in mathematics instruction and employed various strategies that were different from a typical university course, this paper is expected to provide teacher educators with the insight of an alternative teaching style and to provoke discussion of how to connect theory to practice for effective teacher education.