• Journal of Elementary Mathematics Education in Korea
• /
• v.8 no.1
• /
• pp.1-21
• /
• 2004

The purpose of this study is analyzing phenomenon of mathematical communication by students applied story shell. Also, this study is obtained teaching indicated in early standardized mathematics classes. It is served we realize the purpose of study and set study subject to be as follows. First, it finds out how to be described activities of students' mathematical communication in the mathematics class applied story shell. Second, it finds out what phenomenon is observed in a behavior side of the mathematics class applied story shell. It is developed 7 story shells for the 6th grade of the elementary school for about 4 months and when applying mathematics classes, it is analyzed the notes and recorded data to get in an each class and when applying mathematics classes. It is analyzed the notes and recorded data to get in an each class. The result of this study is as follows: First, in a mathematics class which applies story shell, students concentrate on the class when hearing and reading mathematics problem. So, they are able to understand a mathematical language included in the problem. Second, in a mathematics class which applies story shell, students participate actively at the mathematics class. And in complicate situation among the students it is served they justify own opinion and persuaded logically. The point which study hints to see such a result is as follows: First, in a mathematics class which applies story shell students have answered more quickly than the old times as hearing and reading the problem in a picture. Second, in a mathematics class which applies story shell, students were used to being the mathematics language intimately and there was to observe to express it by an equation. Third, in a mathematics class which applies story shell students attend to study activity with interest. Forth, in situation of complicate thought, students are persuading and explaining their opinions for the purpose of justification.

• Proceedings of the Korea Information Processing Society Conference
• /
• 2000.10b
• /
• pp.1345-1348
• /
• 2000

Computers and communication technologies have been brought tremendous change to various aspects of an ever-fast changing world at present. Particularly, the use of internet and cyberspace is widespread in every comer of our life. We developed a cyber shell museum using an animation technology. It was developed for educational purposes, and accessible through the world wide web of internet. Cyber shell museum is consisted of five compartment including rare shells, marvelous shells, shell of the world, the shell of Korea and its story of shells. The database contains the pictures and related information of the shell and it implies not only animation display but also text information. The files of database were classified depending on the species, genus, family, order, and class and division of the shell. Picture of shells is displayed and user may reach the image and virtual view information by clicking through the object displayed. This provides multiple techniques to user may manipulate, visualize and interact with image on the web. And every such transformation as translation, rotation, and scaling can be applied in the picture interactively for the convenient and effective viewing.

• Steel and Composite Structures
• /
• v.50 no.1
• /
• pp.107-122
• /
• 2024

Following an internal column failure, adjacent double-span beams above the failed column will play a critical role in the load transfer and internal force redistribution within the remaining structure, and the span-to-depth ratios of double-span beams significantly influence the structural resistance capacity against progressive collapse. Most existing studies have focused on the collapse-resistant performances of single-story symmetric structures, whereas limited published works are available on the collapse resistances of multi-story steel frames with unequal spans. To this end, in this study, numerical models based on shell elements were employed to investigate the structural behavior of multi-story steel frames with unequal spans. The simulation models were validated using the previous experimental results obtained for single- and two-story steel frames, and the load-displacement responses and internal force development of unequal-span three-story steel frames under three cases were comprehensively analyzed. In addition, the specific contributions of the different mechanism resistances of unequal-span, double-span beams of each story were separated quantitatively using the energy equilibrium theory, with an aim to gain a deeper level of understanding of the load-resistance mechanisms in the unequal-span steel frames. The results showed that the axial and flexural mechanism resistances were determined by the span ratio and linear stiffness ratio of double-span beams, respectively.

• Journal of Welding and Joining
• /
• v.33 no.3
• /
• pp.62-67
• /
• 2015

A very large shell-structure built in shipyards like ship hulls or offshore structures are joined by welding through full process. As the welding contains a high thermal cycle at a local area, the welded structures should be distorted unavoidably. Because a distorted ship block should be revised to the designed value before the next stage, the ability to predict and to control the weld distortion is an accuracy level of the yard itself. Despite the ship block size, several present thermal distortion methodologies can deal those sizes, but it is a different story to deal full ship size model. Even a fully constructed ship hull not remaining any welding can have an accuracy issue like outfitting installation problems. Any present thermal distortion methodology cannot accept this size for its recommended element size and the number. The ordinary welding breadth at erection stage is about 20~40 mm. It can hardly be a good choice to make finite element model of these sizes considering human effort and computational environment. The finite element model for structure analysis of a ship hull is prepared at front-end engineering design stage which is the first process of the project. The element size of the model is as fine as the longitudinal space, and it is not proper to obtain a weld distortion at the erection stage. In this study, a methodology is suggested that a weldment can be shrunk at original place instead of using structural finite element model. We cut the original shell elements at erection weld-line and put truss elements between the edges of cut elements for weld shrinkage. Additional truss elements are used to facsimile transverse weld shrinkage which cannot be from the weld-line truss element shrink. They attach to weld-line truss element like twigs from barks. The capacity of developed elements is verified through an accuracy check of erection process of a container vessel at the apt. hull. It can be a useful tool for verifying a centering accuracy after renew and for block-separating planning considering accuracy.

• Steel and Composite Structures
• /
• v.19 no.5
• /
• pp.1055-1075
• /
• 2015

In order to investigate the accuracy and applicability of steel equivalent constitutive model, the calculated results were compared with typical tests of steel frames under static and dynamic loading patterns firstly. Secondly, four widely used models for time history analysis of steel frames were compared to discuss the applicability and efficiency of different methods, including shell element model, multi-scale model, equivalent constitutive model (ECM) and traditional beam element model (especially bilinear model). Four-story steel frame models of above-mentioned finite element methods were established. The structural deformation, failure modes and the computational efficiency of different models were compared. Finally, the equivalent constitutive model was applied in seismic incremental dynamic analysis of a ten-floor steel frame and compared with the cyclic hardening model without considering damage and degradation. Meanwhile, the effects of damage and degradation on the seismic performance of steel frame were discussed in depth. The analysis results showed that: damages would lead to larger deformations. Therefore, when the calculated results of steel structures subjected to rare earthquake without considering damage were close to the collapse limit, the actual story drift of structure might already exceed the limit, leading to a certain security risk. ECM could simulate the damage and degradation behaviors of steel structures more accurately, and improve the calculation accuracy of traditional beam element model with acceptable computational efficiency.

• Steel and Composite Structures
• /
• v.33 no.1
• /
• pp.1-18
• /
• 2019

In the present study, the behavior of steel plate shear walls (SPSW) with variable column flexural stiffness is experimentally and numerically investigated. Altogether six one-bay one-story specimens, three moment resisting frames (MRFs) and three SPSWs, were designed, fabricated and tested. Column flexural stiffness of the first specimen pair (one MRF and one SPSW) corresponded to the value required by the design codes, while for the second and third pair it was reduced by 18% and 36%, respectively. The quasi-static cyclic test result indicate that SPSW with reduced column flexural stiffness have satisfactory performance up to 4% story drift ratio, allow development of the tension field over the entire infill panel, and cause negligible column "pull-in" deformation which indicates that prescribed minimal column flexural stiffness value, according to AISC 341-10, might be conservative. In addition, finite element (FE) pushover simulations using shell elements were developed. Such FE models can predict SPSW cyclic behavior reasonably well and can be used to conduct numerical parametric analyses. It should be mentioned that these FE models were not able to reproduce column "pull-in" deformation indicating the need for further development of FE simulations with cyclic load introduction which will be part of another paper.

• Structural Engineering and Mechanics
• /
• v.46 no.2
• /
• pp.213-229
• /
• 2013

Although performance based assessment procedures are mainly developed for reinforced concrete and steel buildings, URM (Unreinforced Masonry) buildings occupy significant portion of buildings in earthquake prone areas of the world as well as in IRAN. Variability of material properties, non-engineered nature of the construction and difficulties in structural analysis of masonry walls make analysis of URM buildings challenging. Despite sophisticated finite element models satisfy the modeling requirements, extensive experimental data for definition of material behavior and high computational resources are needed. Recently, nonlinear equivalent frame models which are developed assigning lumped plastic hinges to isotropic and homogenous equivalent frame elements are used for nonlinear modeling of URM buildings. The equivalent frame models are not novel for the analysis of masonry structures, but the actual potentialities have not yet been completely studied, particularly for non-linear applications. In the present paper an effective tool for the non-linear static analysis of 2D masonry walls is presented. The work presented in this study is about performance assessment of unreinforced brick masonry buildings through nonlinear equivalent frame modeling technique. Reliability of the proposed models is tested with a reversed cyclic experiment conducted on a full scale, two-story URM building at the University of Pavia. The pushover curves were found to provide good agreement with the experimental backbone curves. Furthermore, the results of analysis show that EFM (Equivalent Frame Model) with Dolce RO (rigid offset zone) and shell element have good agreement with finite element software and experimental results.

• Journal of the Earthquake Engineering Society of Korea
• /
• v.25 no.3
• /
• pp.93-102
• /
• 2021

The dynamic characterization of a three-story auxiliary building in a nuclear power plant (NPP) constructed with a monolithic reinforced concrete shear wall is investigated in this study. The shear wall is subjected to a joint-research, round-robin analysis organized by the Korea Atomic Energy Research Institute, South Korea, to predict seismic responses of that auxiliary building in NPP through a shake table test. Five different intensity measures of the base excitation are applied to the shaking table test to get the acceleration responses from the different building locations for one horizontal direction (front-back). Simultaneously to understand the global damage scenario of the structure, a frequency search test is conducted after each excitation. The primary motivation of this study is to develop a nonlinear numerical model considering the multi-layered shell element and compare it with the test result to validate through the modal parameter identification and floor responses. In addition, the acceleration amplification factor is evaluated to judge the dynamic behavior of the shear wall with the existing standard, thus providing theoretical support for engineering practice.

• Journal of Korea Foundry Society
• /
• v.40 no.2
• /
• pp.25-33
• /
• 2020

The effects of mold variable and main alloying element on the mechanical properties of ductile cast iron poured into shell stack mold were investigated. The strength and hardness of with the smaller cross-section of the diameter of 6.25mm were higher than those of 12.50mm. On the other hand, the elongation of the former was lower than that of the latter. The strength and hardness of the specimens obtained from the center layer in the 5-story stack mold were the lowest and those for other specimens were increased with increased distance from the center. The elongation of those were the highest of all. The strength and hardness of the specimens obtained from the center layer were decreased the elongation was increased with the increased number of layers. The strength and hardness were increased and the elongation was decreased roughly with the increased amounts of reaidual magnesium and carbon content added, respectively. The strength and hardness were increased and the elongation was decreased roughly with the increased amounts of silicon content added to 2.45wt% and rather decreased with that to 2.85wt%. The effect of silicon content showed the opposite tendency to those of residual magnesium and carbon content.

• Journal of Korea Foundry Society
• /
• v.29 no.3
• /
• pp.128-137
• /
• 2009

The effects of alloying elements on the mechanical properties of 3.6wt%C-2.6wt%C ductile cast iron poured into shell stack molds were investigated. The strength and hardness of the specimens obtained from the center layer in the 5-story stack mold were the lowest and those for other specimens were increased with increased distance from the center. The strength and hardness of the specimens obtained from the center layer were decreased with increased number of layers of the shell stack mold. The strength and hardness of the smaller specimens with the diameter of 9.5 mm were higher than those of 17.5 mm. On the other hand, the elongation of the former was lower than that of the latter. The strength and hardness were increased and the elongation was decreased roughly with the increased amounts of manganese and copper added, respectively. The strength and hardness were increased with the incrcased amount of molybdenum added to 0.40wt% and rather decreased with that to 0.80wt%. Those were greatly increased with the increased amount of tin added and the elongation was roughly decreased with it.