• Journal of Elementary Mathematics Education in Korea
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• v.14 no.1
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• pp.43-64
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• 2010

This study aimed to foster the learning abilities of mathematics, that is, along with the formation of a sure mathematical concept, extending the powers of doing mathematics, and bringing the creativities for 3rd grade elementary school children. In order to achieve these objects, we have executed mathematical classes for two consecutive hours of 16 times using the teaching model of [Learning contents in textbook]$\rightarrow$[The first problem Posing]$\rightarrow$[Problem solving to childrens' posing some problems]$\rightarrow$[Advanced problem posing] to 3rd grade school children during the first semester of 2009. In this paper, we analyzed problems that are made by children focusing on the four fundamental rules +, -, ${\times}$, $\div$ of arithmetic, with the view points of problem's completion, fluencies, flexibilities, buildings of concept, originalities and using materials. As a result of the comparative analysis of the first problems and advanced problems made by the children, the first problems were revealed to be rather better in of problem's completion and fluencies. And the flexibilities were improved in the division and multiplication classes carried on. Setting up the experimental and comparative class, we compared to the scholastic achievement of two classes for the beginning and end in the first semester. In the result, the former was improved in the scholastic achievement more than the latter.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.2
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• pp.9-20
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• 2014

Steel intermediate moment frames (IMFs) have been generally used as seismic load resisting systems (SLRSs) of a building to provide resistances against strong ground shaking. However, most of low and mid-rise steel buildings in Korea were constructed during pre-seismic code era or before the introduction of well-organized current seismic codes. It has been recognized that the seismic performance of these steel IMFs is still questionable. In order to respond to such a question, this study quantitatively investigates the seismic capacities of steel IMFs. Prototype models are built according to the number of stories, the levels of elastic seismic design base shear and the ductilities of structural components. Also, the other prototype models employing hysteretic energy dissipating devices (HEDDs) are considered. The collapse mechanism and the seismic performance of the prototype models are then described based on the results obtained from nonlinear-static and incremental-dynamic analyses. The seismic performance of the prototype models is assessed from collapse margin ratio (CMR) and collapse probability. From the assessment, the prototype model representing new steel IMFs has enough seismic capacities while, the prototype models representing existing steel IMFs provide higher collapse probabilities. From the analytic results of the prototype models retrofitted with HEDDs, the HEDDs enhance the seismic performance and collapse capacity of the existing steel IMFs. This is due to the energy dissipating capacity of the HEDDs and the redistribution of plastic hinges.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.6
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• pp.11-20
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• 2013

In this paper, the quantitative damage index for reinforced concrete (RC) columns with non-seismic details were presented. They are necessary to carry out the postearthquake safety evaluation of RC buildings under 5 stories without seismic details. The static cyclic test of the RC frame sub-assemblage that was an one span and actual-sized was first conducted. The specimen collapsed by the shear failure after flexural yielding of a column, lots of cracks on the surfaces of columns and beam-column joints and the cover concrete splitting at the bottom of columns occurred. The damage levels of these kinds of columns with non-seismic details were classified to five based on the load-displacement relationship by the test result. The residual story drift ratios and crack widths were then adapted as the quantitative index to evaluate the damage limit states because those values were comparatively easy to measure right after earthquakes. The highest one among the residual story drift ratios under the similar maximum story drift ratio decided on the residual story drift ratio of each damage limit state. On the other hand, the lowest and average ones among the respective residual shear and flexural widths under the similar maximum story drift ratio decided on the residual shear and flexural widths of each damage limit state, respectively. These values for each damage limit state resulted in being smaller than those by the international damage evaluation guidelines that are for seismically designed members under the same deformations.

• Proceedings of the Korean Institute Of Construction Engineering and Management
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• 2008.11a
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• pp.256-261
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• 2008

The curtain-wall work has been more frequently applied in the construction industry since demand of high-rise buildings has been increased. The curtain-wall work is usually performed with the frame work simultaneously for reducing construction period, but it might be delayed because of several problems caused by interference of process. However, there is not an appropriate tool which can be used by a work manager for adjusting quantity of the construction equipments or the workers when the curtain-wall work was delayed. To resolve this problem a construction simulation anticipating and analyzing potential problems before starting the work can be applied in the curtain wall work. This research suggests a general model for the curtain-wall work by using construction simulation and produces a combination of construction equipments and workers which can estimate optimum work productivity.

• Journal of the Korea Concrete Institute
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• v.24 no.3
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• pp.259-266
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• 2012

A general earthquake resistant design philosophy of ductile frame buildings allows beams to form plastic hinges adjacent to beam-column connections. In order to carry out this design philosophy, the ultimate bond or shear strength of the beam should be greater than the flexural yielding force and should not degrade before reaching its required ductility. The behavior of RC members dominated by bond or shear action reveals a dramatic reduction of energy dissipation in the hysteretic response due to the severe pinching effects. In this study, a method was proposed to predict the deformability of reinforced concrete members with short-span-to-depth-ratios, which would result in bond failure after flexural yielding. Repeated or cyclic loading produces a progressive deterioration of bond that may lead to failure at lower cyclic bond stress levels. Accumulation of bond damage is caused by the propagation of micro-cracks and progressive crushing of concrete in front of the lugs. The proposed method takes into account bond deterioration due to the degradation of concrete in the post yield range. In order to verify bond deformability of the proposed method, the predicted results were compared with the experimental results of RC members reported in the technical literature. Comparisons between the observed and calculated bond deformability of the tested RC members showed reasonably good agreement.

• Journal of the Earthquake Engineering Society of Korea
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• v.15 no.3
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• pp.37-43
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• 2011

Reliability of piping systems is essential to the safety of any important industrial facilities. During an earthquake, damage to the piping system can occur. It can also cause considerable economic losses and the loss of life following earthquakes. Traditionally, the study of the secondary system was less important than primary structure system, however it has recently been emerging as a key issue for the effective maintenance of the structural system and to help reduce nonstructural earthquake damage. The primary objectives of this study are to evaluate seismic design requirements and the seismic performance of gas and fire protection piping systems installed in reinforced concrete (RC) buildings. In order to characterize the seismic behavior of the existing piping system in an official building, 10 simulated earthquakes and 9 recorded real earthquakes were applied to ground level and the building system by the newmark average acceleration time history method. The results developed by this research can be used for the improvement of new seismic code/regulatory guidelines of secondary systems as well as the improvement of seismic retrofitting or the strengthening of the current piping system.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.9
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• pp.6360-6367
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• 2015

The location selection of the element that should guarantee easy visual perception, like the landmark, is the a topic that appears much in the design process. Recently, a graph analysis technique using computers has been applied in order to evaluate the visibility of the visual element, but the analytic frame is flat and the setting of the visual pont and the matrix are fixed so there were great limitations in obtaining the results of the practical analysis. Thus, this study presented Nondirectional Multi-Dimensional Calculation (MDVC-N), an analytic methodology available for the analysis of the dynamic visual point in the 3D environment. It thus attempted to establish the analytic application using the 3D computer graphics technology and designed a script structure to set the visual point and the matrix. In addition to that, this study tried to verify the analytic methodology by applying the complex land as an example model, where buildings in various heights of terrains with a high-differences are located, verifying the same analytic methodology. It thus tried to identify the visual characteristics of each alternative location. The following results were gained from the study. 1) The visibility can be measured quantitatively trough the application of the 6-alternatives. 2) Using the 3dimensional graph, intuitive analysis was possible. 3) It attempted to improve the analytic applicability by calculating the results corrected as a variable behavior from the local integration variable of the space syntax.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.1
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• pp.35-42
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• 2020

Torsional behavior due to the plane irregularities of the piloti building can cause excessive story drift in the torsionally outermost column, which can lead to shear failure of the column. As a seismic retrofit method that can control the torsional behavior of the piloti building, the expansion of RC wall, steel frame or steel brace may be used, but such methods may hinder the openness of the piloti floor. Therefore, in this study, linear dynamic analysis and nonlinear static analysis for piloti buildings retrofitted by knee brace were performed, and seismic performance evaluation and torsion control effect of knee brace were analyzed. The results showed that the shear force of the column increased when the piloti building retrofitted by knee brace, but it was effective in controlling the torsional deformation. In case of retrofit between knee brace and column by 30°, the shear force of the column increased less than that of 60°, and the lateral displacement of column was decreased in the order of □, ◯ and Ｈ in cross-section.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.34 no.5
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• pp.271-278
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• 2021

According to the capacity design of eccentrically braced frames (EBFs), non-dissipative members such as columns, link-exterior beams, and braces must remain within the elastic region when a fully-yielded and strain-hardened link transmits force to them. The current AISC 341 standard suggests a strain-hardening factor (SHF) of 1.25 for a link under capacity design, regardless of its properties. However, all the links in an EBF are not likely to yield simultaneously to the extent to which the overstrength corresponding to 1.25 times their expected strength is attained, especially for high-rise buildings. Considering this phenomenon, a technique to predict the SHF of links at the limit state of the structure is proposed in this paper. The exact prediction of the links' SHF could save structural quantities dramatically while achieving the principle of capacity design. To validate the effectiveness of this technique, SHF values predicted by conducting linear analysis were compared with those evaluated by nonlinear analysis. Furthermore, the maximum demand-to-capacity ratios of the non-dissipative members were calculated to verify whether they would remain elastic at the limit state of the structure. Consequently, EBFs designed by the proposed method showed substantially economical quantities through the exact prediction of the SHFs, and the intention of capacity design was successfully achieved.

• Journal of the Society of Disaster Information
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• v.18 no.1
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• pp.38-50
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• 2022

Purpose: The goal of this research is to create a numerical analytic database that may assist fire prevention managers and building officials in prioritizing items that need to be addressed in order to improve evacuation safety performance while working within a constrained budget and time frame. Method: It was carried out utilizing the CFD Tool, a quantitative evaluation approach, to assess evacuation safety. One direct staircase-type apartment houses and one corridor-type apartment were chosen to make it. Result: In the fire compartment category, Apartment A's evacuation time was around 130 percent longer than that of sprinkler facilities. Conclusion: Fire prevention managers and building officials feel that starting with a single level and implementing "dwelling unit separations" will increase evacuation safety, and that maintaining fire compartments and sprinkler systems at all times will be effective. Because of the limited characteristics of smoke propagation in corridor-type apartments compared to direct staircase-type flats, it is thought that fire extinguishing equipment should be addressed.