• Steel and Composite Structures
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• v.22 no.4
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• pp.797-820
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• 2016

This paper simulates the hysteretic behavior of steel reinforced recycled concrete (SRRC) columns under cyclic loads using OpenSees software. The effective fiber model and displacement-based beam-column element in OpenSees is applied to each SRRC columns. The Concrete01 material model for recycled aggregate concrete (RAC) and Steel02 material model is proposed to perform the numerical simulation of columns. The constitutive models of RAC, profile steel and rebars in columns were assigned to each fiber element. Based on the modelling method, the analytical models of SRRC columns are established. It shows that the calculated hysteresis loops of most SRRC columns agree well with the test curves. In addition, the parameter studies (i.e., strength grade of RAC, stirrups strength, steel strength and steel ratio) on seismic performance of SRRC columns were also investigated in detail by OpenSees. The calculation results of parameter analysis show that SRRC columns suffered from flexural failure has good seismic performance through the reasonable design. The ductility and bearing capacity of columns increases as the increasing magnitude of steel strength, steel ratio and stirrups strength. Although the bearing capacity of columns increases as the strength grade of RAC increases, the ductility and energy dissipation capacity decreases gradually. Based on the test and numerical results, the flexural failure mechanism of SRRC columns were analysed in detail. The computing theories of the normal section of bearing capacity for the eccentrically loaded columns were adopted to calculate the nominal bending strength of SRRC columns subjected to vertical axial force under lateral cyclic loads. The calculation formulas of horizontal bearing capacity for SRRC columns were proposed based on their nominal bending strength.

• Journal of the Korea Institute of Building Construction
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• v.18 no.6
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• pp.517-525
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• 2018

The construction of super tall building which structure is RC and must be certainly considered on column shortening estimation and construction reflected concrete creep has been increased. Regarding the Fck 60~80MPa grade high strength concrete applied in the domestic super tall building project, the mechanical properties and creep deflection according to curing conditions(Drying creep/Basic creep) were reviewed in this research. Results of compressive strength and elastic modulus under sealed curing condition were 5% higher than unsealed condition and difference of results according to the curing condition was increased over time. Autogenous and drying shrinkage tendency showed adversely in the case of high strength concrete. Additionally, creep modulus under unseal curing condition was evaluated 2~3 times higher than sealed condition. Modified model of ACI-209 based on test result was applied to estimate long period shortening of vertical members(such as Core Wall/Mega Column) exactly, it is designed to modify and suggest the optimal creep model based on various data accumulated during construction, in the future.

• The Mathematical Education
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• v.61 no.1
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• pp.127-156
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• 2022

This study used the data of students from the 6th grade to the 3rd grade of middle schoolin the Korean Educational Longitudinal Study 2013 and classified them into subgroups with similar longitudinal changes in math academic achievement. In addition, the influence of longitudinal changes in the group's academic self-concept and teachers and parents academic support on the longitudinal changes in math academic achievement were analyzed, either directly or indirectly. As a result of the analysis, it was found that the academic self-concept of each group had a positive influence on the academic achievement in mathematics. In addition, the academic support of teachers and parents was found to have a positive influence on the academic achievement in mathematics through the mediating of the academic self-concept. In terms of direct and indirect influence on academic self-concept and math vertical scale scores, it was found that teachers' academic support had more influence than parents' academic support. The educational implications of these points were discussed.

• Korean Institute of Interior Design Journal
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• v.20 no.6
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• pp.311-320
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• 2011

Public libraries in Korea have undergone changes from libraries for just reading or keeping books to libraries with cultural facilities that provide information through various media. It was because of the "plan for building the information-oriented library" in 2000 that made the complexation of public library in progress. The alterations of the system have changed the structure as well as the grade ranks but haven't been considered enough for administrators or visitors. Hereupon, we are to study of the features by analyzing how the application of the system changed the structure of library. There are four stages in research methods. First, concept of public library and functional elements requested in the process of complexation were studied from literature. Second, vertical, horizontal and circulate changes were studied by applying subject libraries into prior research stereotyping the libraries. Third, mutual relations between each place were studied through J-Graph by elements. Lastly, rank changes according to centrality of space and users were quantitatively studied with space syntax. 4 notable changes were found in these analyses. (1)Vertical, horizontal and circulate structure of public libraries were homogenized. Since 2001, however, they have become diversified as all-in-one or detachable. (2)The space structure of library before 2001 was shallow tree shape while in 2001, period of transition, was the tree shape mixed with ring shape. As time goes on, it has become shallow tree shape again but connected by ring shape in part of reading and common space and in digital reference room. (3)Digital reference room was center of the space around 2001 and it ranked top for integration. After 2007, however, it has become setting off-center. (4)About the purpose of using public libraries, using it as space for administrators ranked top followed by space for visitors and common space before. For now, common space ranks top and space for visitors and administrators. 5 subject public libraries were selected respectively before and after 2001.

• Journal of Chest Surgery
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• v.23 no.5
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• pp.962-967
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• 1990

The anomalous pulmonary venous return of the entire left lung was an extremely rare congenital anomaly. The reported surgical experience with correction of this disorder was limited. The 3-year-old female patient underwent an operation upon the unilateral total anomalous pulmonary venous return from the left lung, in which the left superior pulmonary vein drained into innominate vein and the left inferior pulmonary vein into the coronary sinus, in Yeungnam University Hospital. The symptoms were nonspecific except frequent upper respiratory infection. Cyanosis was not seen. On auscultatory findings, a grade 2/6 systolic ejection murmur was audible over left second intercostal space of left sternal border and second heart sound had an increased pulmonary component which was widely splitted. The electrocardiogram demonstrated a right ventricular hypertrophy and right axis deviation and chest X-ray showed slightly increased pulmonary vascularity and bulged pulmonary conus. The echocardiogram demonstrated increased right atrial, ventricular, and pulmonary arterial dimension, and also secundum atrial septal defect and enlarged coronary sinus. The cardiac catheterization confirmed the left-to-right with a Qp/Qs of 2.0: 1 and oxygen step-up was seen in pulmonary artery, right ventricle, right atrium, and left innominate vein, and the catheter was not been introduced into the left pulmonary vein. A median sternotomy incision was done. Left superior pulmonary vein was drained to the innominate vein through anomalous vertical vein and the left inferior pulmonary vein drained to right atrium through the coronary sinus. The diversion of the left inferior pulmonary vein to posterior wall of left atrium was done after division in the proximity of coronary sinus. The anomalous vertical vein was diverted to base of left atrial auricle and then a atrial septal defect was sutured directly. The postoperative course was uneventful and she was discharged on the eleventh postoperative day. In the postoperative follow-up-2 months, she has been well without specific problems.

• Journal of Korean Society of Transportation
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• v.30 no.5
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• pp.61-69
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• 2012

It is important for highway maintenance and safety assessment to get the accurate highway geometric information. However, it is difficult to acquire good highway geometric information due to missing blueprints or deteriorated highway sections. This research, to get highway geometric information rapidly, has developed a highway geometric analysis algorithm that uses data from vehicles with GPS-IMU integrated system. In conclusion, the result shows that 3.38% of error-ratio for the horizontal alignment and 0.083 absolute value difference for vertical grade comparing with highway drawings. Therefore, the result suggest that the developed method can be applied to the road safety inspection or road safety audit.

• Journal of the Korean School Mathematics Society
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• v.18 no.4
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• pp.353-370
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• 2015

This study was conducted as a qualitative case study that explored how gifted 3rd-grade elementary school children who had learned the primary concepts of division and fraction, when they studied contents about decimal, formed the transformed primary concept and transformed schema of decimal by the learning of accurate primary concepts and connecting the concepts. That is, this study investigated how the subjects attained relational understanding of decimal based on the primary concepts of division and fraction, and how they formed a transformed primary concept based on the primary concept of decimal and carried out vertical mathematizing. According to the findings of this study, transformed primary concepts formed through the learning of accurate primary concepts, and schemas and transformed schemas built through the connection of the concepts played as crucial factors for the children's relational understanding of decimal and their vertical mathematizing.

• Journal of Korean Society of Transportation
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• v.25 no.5
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• pp.67-77
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• 2007

This study deals with the traffic accidents at the unsignalized intersections in Cheongju. The purpose is to analyze the characters and the relations between road environmental factors and traffic accidents. The correlation analyses among the above factors show that the accidents are strongly related to traffic volumes and sight distances in 3-legged, and the cross angles, maximum vertical grades and sight distances in 4-legged unsignalized intersections. Also the multiple linear and nonlinear regression analyses represent that the accidents in the 3-legged increase as the traffic volume and the number of double stop-lines increase, and that the accidents in the 4-legged increase as the cross angle approaches to the 90 degree and decrease as the maximum vertical grade increases. It could be expected that this results give the good implications to the future intersection improvement projects in Cheongju.

• Korean Journal of Applied Biomechanics
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• v.17 no.3
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• pp.181-188
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• 2007

The purpose of this study was to investigate the biomechanical effects of wearing different type of insole shoes on gait characteristics in patients with knee osteoarthritis. Seven patients with knee osteoarthritis (Grade 3 & 4 by Kellgren & Lawrence) were participated in the study. They wore two different type of shoes (with Gel-type Insole: GIS, with Normal insole: NIS) during gait. Three dimensional cinematography and Ground Reaction Force(GRF) data were used to get the maximal value of horizontal distance between the center of pressure in GRF and knee joint center, GRF in mediolateral direction, peak value of GRF in frontal plane, vertical compressive force and adduction moment in knee joint. The results were as follows: The maximal value of horizontal distance between the center of pressure in GRF and knee joint center was smaller in GIS than NIS. The peak value of GRF in mediolateral direction was found in 30% of gait cycle, five subjects wearing GIS showed lower value of peak GRF in mediolateral direction than wearing NIS. The peak value of GRF in frontal plane and vertical compressive force in knee joint did not show any difference between GIS and NIS. The adduction moment in GIS decreased in the late stance of gait and the mean value of the adduction moment in GIS smaller than that in NIS. GIS may help to move quickly knee joint center to the center of pressure in GRF, therefore it may prevent increasing the adduction moment in knee joint.

• Journal of Elementary Mathematics Education in Korea
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• v.15 no.2
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• pp.247-282
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• 2011

In the elementary school mathematics textbooks of the 7th national curriculum, just simple construction education is provided by having students draw a circle and triangle with compasses and drawing vertical and parallel lines with a set square. The purpose of this study was to examine the mathematical thinking of sixth-grade elementary school students in the construction process in a bid to give some suggestions on elementary construction guidance. As a result of teaching the sixth graders in gifted and nongifted classes about the equal division of line segments and evaluating their mathematical thinking, the following conclusion was reached, and there are some suggestions about that education: First, the sixth graders in the gifted classes were excellent enough to do mathematical thinking such as analogical thinking, deductive thinking, developmental thinking, generalizing thinking and symbolizing thinking when they learned to divide line segments equally and were given proper advice from their teacher. Second, the students who solved the problems without any advice or hint from the teacher didn't necessarily do lots of mathematical thinking. Third, tough construction such as the equal division of line segments was elusive for the students in the nongifted class, but it's possible for them to learn how to draw a perpendicular at midpoint, quadrangle or rhombus and extend a line by using compasses, which are more enriched construction that what's required by the current curriculum. Fourth, the students in the gifted and nongifted classes schematized the problems and symbolized the components and problem-solving process of the problems when they received process of the proble. Since they the urally got to use signs to explain their construction process, construction education could provide a good opportunity for sixth-grade students to make use of signs.