• Korean Journal of Mathematics
• /
• v.13 no.1
• /
• pp.1-11
• /
• 2005

The purpose of the present paper is to introduce a new concept of the E($^*{\kappa}$)-connection ${\Gamma}^{\nu}_{{\lambda}{\mu}}$, which is both Einstein and ($^*{\kappa}$)-connection, and to obtain a necessary and sufficient condition for the existence of the unique E($^*{\kappa}$)-connection in $n-^*g$-UFT. Next, under this condition, we shall obtain a surveyable tensorial representation of the unique E($^*{\kappa}$)-connection in $n-^*g$-UFT.

• The Journal of Korean Academy of Prosthodontics
• /
• v.49 no.4
• /
• pp.346-353
• /
• 2011

Purpose: The peri-implant soft tissue is remodeled by the initial marginal bone resorption affecting the prognosis and esthetic result of treatment. Thus various designs on implant neck design are studied to preserve peri-implant bone. The purpose of this study is to review on the causes of initial marginal bone resorption, the configuration of peri-implant soft tissue, and the implant crestal module favorable in preserving peri-implant tissue. Materials and methods: The studies on the causes of initial marginal bone resorption and the implant crestal modules are researched and reviewed using Pubmed database. The implant crestal modules including one piece and two-piece implant, internal and external hex abutment, taper and butt joint connection, scalloped design abutment, and platform switching concept are reviewed. Results: A number of clinical and experimental studies preferred one piece implant to two-piece in preserving initial peri-implant tissue. For two piece implants, internal hex abutment and taper joint connection appear more favorable than external hex abutment and butt joint connection relatively. Controversial issues still exist on scalloped design requiring more studies on it. Although the rationale is not certain, the concept of platform switching seems favorable in preserving initial peri-implant tissue based on clinical and experimental studies. Conclusion: Each implant crestal module contains its own advantages and disadvantages with various controversial issues. In the aspect of preservation of initial peri-implant tissue, however, one-piece implant seems beneficial. In cases when two-piece implant is more appropriate due to prosthodontic concerns or any other problems, the application of platform switching concept, internal connection abutment, and taper joint connection may be favorable for the preservation of peri-implant tissues.

• Education of Primary School Mathematics
• /
• v.15 no.3
• /
• pp.201-218
• /
• 2012

In this study, the following topics were investigated targeting elementary school students: Schema formed through precise notion of cognitive and the connection of the concepts when studying common divisor, common multiple, and the lowest common multiple, configuration ability and problem solving of the students when learning using a modified schema, how the schema of the student to advance to a higher level, and how the deformation of the schema is carried out student's configuration of concept and problem solving ability. As a result, it was found out that cognition about precise concept, schema and the modified schema are important factors when a primary concept was developed into a secondary concept, and play important roles when the connection and the formation of the modified schema created by cognition about the precise primary concept rather than by the formation of the secondary concept (formation of the secondary schema) created by the connection between the primary concept.

• The Mathematical Education
• /
• v.51 no.4
• /
• pp.455-469
• /
• 2012

Given the importance of mathematical connections in instruction, this paper analyzed the objects and the methods of mathematical connections according to the lesson flow featured in 20 elementary lessons selected as effective instructional methods by local educational offices in Korea. Mathematical connections tended to occur mainly in the introduction, the first activity, and the sum-up period of each lesson. The connection between mathematical concept and procedure was the most popular followed by the connection between concept and real-life context. The most prevalent method of mathematical connections was through communication, specifically the communication between the teacher and students, followed by representation. Overall it seems that the objects and the methods of mathematical connections were diverse and prevalent, but the detailed analysis of such cases showed the lack of meaningful connection. These results urge us to investigate reasons behind these seemingly good features but not-enough connections, and to suggest implications for well-connected mathematics teaching.

• Korean Institute of Interior Design Journal
• /
• v.13 no.2
• /
• pp.29-37
• /
• 2004

This study analyze the architectural space in the aspect of the 'Raumplan' and 'Plan Libre'. These concepts based on the 'Raumplan versus Plan Libre' exhibition in Delft University, Netherlands. It is generally agreed that the concept of 'Plan Libre' in connection with Le Corbusie architecture and 'Raumplan' related to Adolf Loos's works. that exhibition contents was focused an extent of modem architecture. But, These concepts continually influence contemporary architecture and offer diverse vision in architecture. Therefore, this study focused on the analysis that look for common element in the space through the case study and space element connection in change of the values, technical growth. This Paper reveals that Adolf Loos's Raumplan is similar to Louis I. Kahn's 'Room' concept and Ando Tadao's centrifugal space composition method In the dwelling architecture. And the concept 'Plan Libre': non-definitive formal system and the elements : column, free form screening wall is revived as formal application of 3 dimension composition in architecture. and transfer lots, void, and linear space in Rem Koolhaas's urban design projects. These aspects is so called topology. This topological concept is an attempt in view of the space connection state rather than formative viewpoint.

• Steel and Composite Structures
• /
• v.21 no.6
• /
• pp.1251-1264
• /
• 2016

After observing relatively poor performance of bolted web-welded flange beam-to-column connections during 1994 Northridge earthquake, various types of connections based on two concepts of: (i) strengthening the connection; and (ii) weakening the beam ends were proposed. Among these modified or newly proposed connections, bolted T-stub connection follows the concept of strengthening. One of the connections with the idea of weakening the beam ends is reduced beam section (RBS). In this paper, finite element simulation is used to study the cyclic behavior of a new proposed connection developed by using a combination of both mentioned concepts. Investigated connections are exterior beam-to-column connections designed to comply with AISC provisions. The results show that moment capacity and dissipated energy of the new proposed connection is almost the same as those computed for a T-stub connection and higher than corresponding values for an RBS connection.

• Steel and Composite Structures
• /
• v.6 no.3
• /
• pp.203-219
• /
• 2006

One of the most promising ways through which a steel moment frame may attain high energy dissipating capability is to trim off a portion of the beam flanges near the column face. This type of moment connection, known as Reduced Beam Section (RBS) connection, has notable superiority in comparison with other moment connection types. As the result of the advantages of RBS moment connection, it has widely being used in practice. In spite of the good hysteretic behaviour, an RBS beam suffers from an undesirable drawback, which is local and lateral instability of the beam. The instability in the RBS beam reduces beam load-carrying capacity. This paper aims to investigate key issues influencing cyclic behaviour of RBS beams. To this end, a numerical analysis was conducted on a series of steel subassemblies with various geometric properties. The obtained results together with the existing experimental data are used to study the instability of RBS beams. A new slenderness concept is presented to control an RBS beam for combined local and lateral instability. This concept is in good agreement with the numerical and experimental results. Finally, a model is developed for the prediction of the magnitude of moment degradation owing to the instability of an RBS beam.

• Communications of Mathematical Education
• /
• v.29 no.1
• /
• pp.131-155
• /
• 2015

The purpose of this study is to investigate if top-ranked high school students do integrated understanding about the concept of a differential coefficient. For here, the meaning of integrated understanding about the concept of a differential coefficient is whether students understand tangent and velocity problems, which are occurrence contexts of a differential coefficient, by connecting with the concept of a differential coefficient and organically understand the concept, algebraic and geometrical expression of a differential coefficient and applied situations about a differential coefficient. For this, 38 top-ranked high school students, who are attending S high school, located in Cheongju, were selected as subjects of this analysis. The test was developed with high-school math II textbooks and various other books and revised and supplemented by practising teachers and experts. It is composed of 11 questions. Question 1 and 2-(1) are about the connection between the concept of a differential coefficient and algebraic and geometrical expression, question 2-(2) and 4 are about the connection between occurrence context of the concept and the concept itself, question 3 and 10 are about the connection between the expression with algebra and geometry. Question 5 to 9 are about applied situations. Question 6 is about the connection between the concept and application of a differential coefficient, question 8 is about the connection between application of a differential coefficient and expression with algebra, question 5 and 7 are about the connection between application of a differential coefficient, used besides math, and expression with geometry and question 9 is about the connection between application of a differential coefficient, used within math, and expression with geometry. The research shows the high rate of students, who organizationally understand the concept of a differential coefficient and algebraic and geometrical expression. However, for other connections, the rates of students are nearly half of it or lower than half.

• Journal of Elementary Mathematics Education in Korea
• /
• v.19 no.4
• /
• pp.563-588
• /
• 2015

In elementary school, didactical transposition is inevitable due to several reasons. In mathematics, addition and multiplication are taught as binary operations, subtraction and division are taught as unary operations. But in elementary school, we try to teach all the four operations as binary operations by didactical transposition. In 'Mastering' the concepts of the four operations, the way of concept introduction is dealt importantantly. So it is different from understanding the four operations. In this study, we analyzed the four operations of natural numbers and fractions from two perspectives: concept understanding (how to introduce concepts and how to choose an operation) and connection between the operations. As a result, following implications were obtained. In division of fractions, students attempted a connection with multiplication of fractions right away without choosing an operation, based on the situation. Also, to understand division of fractions itself, integrate division of fractions presented from the second semester of the fifth grade to the first semester of the sixth grade are needed. In addition, this result can be useful in the future textbook development.

• Steel and Composite Structures
• /
• v.7 no.1
• /
• pp.71-85
• /
• 2007

This study suggests modular composite profile beams, where the prefab concept is applied to existing composite profile beams. The prefab concept produces a beam of desired size having two types of profile: side module and bottom module. Module section will improve construction efforts because it offers several benefits : reduction of deflections due to creep and shrinkage, which might be found in existing composite profile beams; increase in span/depth ratio; and free prefabrication of any required beams. Based on the established analysis theory of composite profile beams, an analysis theory of modular composite profile beams was suggested, and analysis values were compared with experimental ones. The behavior of individual modules with increase of load was measured with a strain gauge, and the shear connection ratio between modules was analyzed by using the measured values. As a result of experiment, it was found that theoretical flexural strength on condition of full connection was 57%-80% by connection of modules for each specimen, and it is expected that flexural strength will approximate the theoretical levels through further module improvement.