• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2004.04a
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• pp.95-99
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• 2004

This paper describe inner-collision-characteristics of the ship structural plates when the projectile collides with plate-material using LS-DYNA3D which is general and useful finite element analysis tool in collision problem fields. The series analyses were carried out from high speed(41.56m／s-118.9m／s) to ultrahigh speed(544.05m／s-800m／s). Through these analyses we can approach empirical formula to estimate penetration limit of the ship structural plates with which the projectile of various speed collides.

• Education of Primary School Mathematics
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• v.14 no.3
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• pp.317-328
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• 2011

We analyzed errors committed by Korean prospective elementary teachers in finding and interpreting quotient and remainder within measurement division of fractions. 65 prospective elementary teachers were participated in this study. They solved a word problem about measurement division of fractions. We analyzed solutions of all participants, and interviewed 5 participants of them. The results reveal many of these prospective teachers could not tell what fractional part of division result means. Thses results suggest that teacher preparation program should emphasize interpreting calculation results within given situations.

• Communications of Mathematical Education
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• v.31 no.1
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• pp.71-84
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• 2017

Taylor series has a complicated structure comprising of various concepts in college major mathematics. This subject is a strong tool which has usefulness and applications not only in calculus, analysis, and complex analysis but also in physics, engineering etc., and other study. However, students have difficulties in understanding mathematical structure of Taylor series convergence correctly. In this study, after classifying students' mathematical characteristic into three categories, we use structural image of Taylor series convergence which associated with mathematical structure and operation acted on that structure. Thus, we try to analyze the understanding of Taylor series convergence and present the results of this study.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.5 s.57
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• pp.93-100
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• 2009

This study presents reasonable relationships to estimate the deformation based on beam mechanism analysis and TDR(Time Domain Reflectometry) data. To declar the length points of co-axial cable installed in civil structure, Nano material ($BaTiO_3$ powders and silver mixture) is used on co-axial cables. From the laboratory test, nano material could make the correct information about attached cable points on beam, and TDR sensor system and Fourier series (data filter) found out the deformation of beam. Therefore it is concluded that the correct deformed information of beam were acquired by Nano-TDR and Fourier filter, they are much more effective to apply at health monitoring system in civil structure compared to conventional TDR or Fiber Optic Sensor (FOS) systems.

• Journal of the Society of Naval Architects of Korea
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• v.31 no.3
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• pp.119-128
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• 1994

Deflection estimation at engine room upper deck panel is performed for the actual ship structure. These deflection behaviours are basically investigated from not only the data based on the full series results of nonlinear analysis using Incremental Galerkin's Method but also actual deflection data measured from damaged ship under construction in dry dock. The effects of residual stress, initial deflection and static loading are also included. The computed estimation results of upper deck plate panel including theme effects are shown that upper deck platings of new ship expected less deflection magnitude than damaged ship.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.33 no.3
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• pp.145-152
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• 2020

In this study, we evaluated spinal stability based on the change in the thoracolumbar fixation segment using finite element analysis (FEA). To accomplish this, a finite element (FE) model of a normal thoracolumbar spine (T10-L4), including intervertebral discs (IVD), ligaments, and facet joints, was constructed, and the material properties reported in previous studies were implemented. However, L1 was assumed as the lesion site, and three types of posterior fixation, namely, L1-L2, T12-L2, and T12-L1-L2, were implemented in the thoracolumbar FE model. In addition, the loading conditions for flexion, extension, lateral bending, and axial rotation were adopted. Through the series FEA, the deformation, equivalent stress, range of motion, and moment on the pedicle screws, vertebrae, and IVD were calculated, and the spinal stability was evaluated based on the FEA results.

• Journal of the Society of Naval Architects of Korea
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• v.37 no.4
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• pp.92-105
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• 2000

A study for the structural strength evaluation on the slender doubler plate has been performed through the systematic evaluation process. In order to estimate the proper static strength of doubler plate subjected to the longitudinal in-plane compression, elasto-plastic large deflection analysis is introduced including the contact effect between main plate and doubler. The characteristics of stiffness and strength variation are discussed based on their results. Also, in order to compare the doubler structure with the original strength of main plate without doubler, a simple formula for the evaluation of the equivalent flat plate thickness is derived based on the additional series analysis of flat plate structure. Using this derived equation, the thickness change of a equivalent flat plate is analyzed according to the variation of various design parameters of doubler plate and some design guides are suggested in order to maintain the original strength of main plate without doubler reinforcement. Finally, correlation between derived equivalent flat plate formula and the developed buckling strength formulas by author et al. is discovered and these relations are formulated for the future development of simple strength evaluation formula of doubler plate structure.

• The Mathematical Education
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• v.58 no.3
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• pp.347-365
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• 2019

It is important to pay attention to how teachers recognize and use curriculum materials in order to link written curriculum and enacted curriculum. In this study, 90 preservice mathematics teachers were surveyed to identify their perspective and reading of curriculum materials. Especially, we focused on the curriculum documents, textbooks, and teachers' guidebooks containing the concept of conditional probability which is addressed in highschool mathematics curriculum. The various misconceptions of conditional probability were reported in the many researches, and there are multiple methods to introduce conditional probability in mathematics classes. As a result, curriculum materials have some limits to be used as they are and considered to be reconstructable by participants, but their curriculum reading were mainly classified to be descriptive and evaluative, not to be interpretive. However, unlike curriculum documents, textbooks and teachers' guidebooks were partially interpreted by participants using their knowledge of conditional probability. The purpose of this study is to investigate the profession of mathematics teachers in terms of curriculum implementation. We expect that this study will provide a basic framework for analyzing mathematics teachers' works and suggest some implications for the professional development of mathematics teachers.

• Education of Primary School Mathematics
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• v.24 no.2
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• pp.83-102
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• 2021

Curricular noticing is about how teachers understand the content and pedagogical opportunities inherent in curriculum materials. Since the enacted curriculum differs depending on which aspect of the curriculum material is paid attention to and how to interpret it, it is necessary to focus on Curricular Attending and Curricular Interpreting in Curricular Noticing for enhancing the teaching expertise of preservice teachers. First, this study categorized the objects that preservice elementary mathematics teachers attended when planning the lesson for rate. Second, in order to find out the reason for paying attention to those objects, it was analyzed what factors were related to interpret. By discussing the results, implications were drawn on how to use Curricular Noticing in preservice teacher education to enhance the pedagogical design competency of preservice elementary mathematics teachers.

• Aerospace Engineering and Technology
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• v.3 no.1
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• pp.155-169
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• 2004

Space launch vehicles and reentry vehicles are exposed to extreme heating conditions due to high aerodynamic heating while flying at high Mach numbers in the atmosphere. To protect the vehicle itself or the payload from the aerodynamic heating, the thermal load imposed on the surface should be exactly predicted and proper thermal protection should be applied based on the prediction results. But this requires rigorous thermal analysis and testing to prevent loss of payload capacity caused by excessive heat shielding, and the amount of thermal protection material to be applied is determined through aerodynamic heating tests. Various design points to be considered to upgrade the prototype aerodynamic thermal simulation facility(ATSF) used for the KSR-series sounding rocket development to the one suitable for the KSLV(Korean Space Launch Vehicle)-series launch vehicle are considered in this research. The need and limitation for the facility are first considered, and the functions required for KSLV testing are determined. The specifications of the upgraded facility are briefly suggested and these results will be used for the future fabrication and installation of the facility.