• Proceedings of the KWS Conference
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• 2004.05a
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• pp.118-120
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• 2004

The non-destructive examinations for Yonggwang unit 6 was conducted in four different fields, these are 1)all non-destructive inspections for components, piping weldments and structures, 2)automated ultrasonic inspection for pressure vessels weldments. As the results, there were no big indications, and all indications detected during inspection were evaluated as the metallurgical and geometrical non-reinvent indications form weldments. Especially for the weldment of pipes, PD(Performance Demonstration) was applied as a UT inspection method according to 1995 edition of ASME code Sex. XI, this resulted in improvement of the reliability of UT inspection.

• International Journal of Naval Architecture and Ocean Engineering
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• v.3 no.1
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• pp.27-36
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• 2011

In the proposed paper numerical calculations are carried out using two versions of a three-dimensional, timedomain panel method developed by the group of Prof. P. Sclavounos at MIT, i.e. the linear code SWAN2, enabling optionally the use of the instantaneous non-linear Froude-Krylov and hydrostatic forces and the fully non-linear SWAN4. The analytical results are compared with experimental results for three hull forms with increasing geometrical complexity, the Series 60, a reefer vessel with stern bulb and a modern fast ROPAX hull form with hollow bottom in the stern region. The details of the geometrical modeling of the hull forms are discussed. In addition, since SWAN4 does not support transom sterns, only the two versions of SWAN2 were evaluated over experimental results for the parent hull form of the NTUA double-chine, wide-transom, high-speed monohull series. The effect of speed on the numerical predictions was investigated. It is concluded that both versions of SWAN2 the linear and the one with the non-linear Froude-Krylov and hydrostatic forces provide a more robust tool for prediction of the dynamic response of the vessels than the non-linear SWAN4 code. In general, their results are close to what was expected on the basis of experience. Furthermore, the use of the option of non-linear Froude-Krylov and hydrostatic forces is beneficial for the accuracy of the predictions. The content of the paper is based on the Diploma thesis of the second author, supervised by the first one and further refined by the third one.

• Journal for History of Mathematics
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• v.21 no.2
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• pp.81-90
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• 2008

It has been noticed the greater importance of mathematical education, particularly of multi-variable calculus in the undergraduate level with remarkable progress of all sorts of sciences requiring mathematical analysis. However, there was lack of variety of introducing the definition of differentiation of multi-variable functions - in fact, all of them basically rely on the chain rules. Here we will introduce a way of defining the geometrical differentiation of the multi-variable functions based upon our teaching experience. One of its merits is that it provides the geometric explanation of the differentiation of the multi-variable functions, so that it conveys the meaning of the differentiation better compared with the known methods.

• Transactions of Materials Processing
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• v.4 no.1
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• pp.28-38
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• 1995

An integrated process planning system can determine desirable operation sequences even if they have little experience in the design of multistage cold forging process. This system is composed of seven major modules such as input module, pre-design module, formability check module, forming sequence design module, forming analysis module, FEM verification module, and output module which are used independently or in all. The forming sequence for the part can be determined by means of primitive geometries such as cylinder, cone, convex, and concave. By utilizing this geometrical characteristics(diameter, height, and radius), the part geometry is expressed by a list of the primitive geometries. Accordingly, the forming sequence design is formulated as the search problem which starts with a billet geometry and finishes with a given product one. Using the developed system, the sequence drawing with all dimensions, which includes the dimensional tolerances and the proper sequence of operations for parts, is generated under the environment of AutoCAD. Several forming sequences generated by the planning system can be checked by the forming analysis module. The acceptable forming sequences can be verified further, using FE simulation.

• Journal of KSNVE
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• v.11 no.1
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• pp.82-88
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• 2001

In a transmission or geared rotor system a coupled phenomenon of lateral and torsional vibrations may occur due to the gear meshing effect. Particularly, in high speed or low vibration and low noise applications of geared rotor systems a coupled rotordynamic analysis is required to precisely predict their dynamic characteristics. In this paper a generalized finite element model of a gear pair element is developed, which actively couples the lateral and torsional vibrations due to the gear meshing effect. In the modeling the generalized forces due to the transmission error. geometrical eccentricities. and unbalances in the gear system are also considered. Then. using the developed gear pair element model a coupled unforced rotordynamic analysis is performed with a prototype 800 RT turbo-chiller rotor-bearing system having a hull-pinion speed increasing gear. Results show that the torsional vibration characteristics experience some changes due to the gear meshing and lateral dynamic coupling effect, but that they have no adverse effect and the lateral ones have no practical changes in an operating speed range.

• Computers and Concrete
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• v.17 no.1
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• pp.141-156
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• 2016

The search for new structural systems capable of associating performance and safety requires deeper knowledge regarding the mechanical behavior of structures subject to different loading conditions. The Strut-and-Tie Model is commonly used to structurally designing some reinforced concrete elements and for the regions where geometrical modifications and stress concentrations are observed, called "regions D". This method allows a better structural behavior representation for strength mechanisms in the concrete structures. Nonetheless, the topological model choice depends on the designer's experience regarding compatibility between internal flux of loads, geometry and boundary/initial conditions. Thus, there is some difficulty in its applications, once the model conception presents some uncertainty. In this context, the present work aims to apply the Strut-and-Tie Model to nonlinear structural elements together with a topological optimization method. The topological optimization method adopted considers the progressive stiffness reduction of finite elements with low stress values. The analyses performed could help the structural designer to better understand structural conceptions, guaranteeing the safety and the reliability in the solution of complex problems involving structural concrete.

• Korean Institute of Interior Design Journal
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• v.16 no.6
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• pp.11-18
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• 2007

Edward Hopper is one of the great American artists in the 20th Century. In the field of art, it seems that his paintings are thoroughly analyzed In terms of human alienation and emotional aspects in various ways. However, in his numerous paintings, highly interesting spatial aspects can be found. Purpose of this study is to analyze some of his painting by the spatially analytical tools to examine how his space is experienced. The tools are: relationship between each space, relationship between light and space, and geometrical composition. Among many paintings by Hopper, four of the works that depicted interior spaces are selected and further case-studied in detail: ${\ulcorner}$Rooms by the Sea${\lrcorner}$ (1951), ${\ulcorner}$Sun in an Empty Room${\lrcorner}$ (1963), ${\ulcorner}$New York Movie${\lrcorner}$ (1939) and ${\ulcorner}$Automat${\lrcorner}$ (1927). An Environmental Simulation with scale models was used to examine the relation between light and space. After the research, some unique characteristics of his space were found. Even though his paintings seem to represent the everyday spaces, there are fascinating hidden structure to make people experience in a specific way that Hopper created. Spaces In his paintings do not communicate with each other but are constantly interrupted by the element of time. The mundane everyday world is rediscovered and recreated through these multidimensional and heterogeneous space.

• The Mathematical Education
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• v.53 no.2
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• pp.275-290
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• 2014

This study investigated the types of the 3D geometric thinking and spatial reasoning through the observation of the 2D representing activities for representing the 3D geometrical objects with preservice secondary mathematics teachers. For this purpose, the 43 sophomoric students in college of education were divided into 10 groups and observed their group task performance on the basis of the representation they used. Observed processes were all recorded and the participants were interviewed based on the task. As a result, the role of physical object that becoming the object of geometric thinking and spatial reasoning, and diverse strategies and phenomena of the process that representing the 3D geometric figures in 2D were discovered. Furthermore, these processes of representing were assumed to be influenced by experience and study practice of students, and various forms of representing process were also discovered in the process of small group activities.

• Education of Primary School Mathematics
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• v.14 no.1
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• pp.13-26
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• 2011

The purpose of this research is to analyze geometrical level and the justification process in the proofs of construction by mathematically gifted elementary students. Justification is one of crucial aspect in geometry learning. However, justification is considered as a difficult domain in geometry due to overemphasizing deductive justification. Therefore, researchers used construction with which the students could reveal their justification processes. We also investigated geometrical thought of the mathematically gifted students based on van Hieles's Theory. We analyzed intellectual of the justification process in geometric construction by the mathematically gifted students. 18 mathematically gifted students showed their justification processes when they were explaining their mathematical reasoning in construction. Also, students used the GSP program in some lessons and at home and tested students' geometric levels using the van Hieles's theory. However, we used pencil and paper worksheets for the analyses. The findings show that the levels of van Hieles's geometric thinking of the most gifted students were on from 2 to 3. In the process of justification, they used cut and paste strategies and also used concrete numbers and recalled the previous learning experience. Most of them did not show original ideas of justification during their proofs. We need to use a more sophisticative tasks and approaches so that we can lead gifted students to produce a more creative thinking.

• The Journal of Korean Society for Radiation Therapy
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• v.11 no.1
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• pp.100-105
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• 1999

Purpose : When the value of X,Y,Z coordination of the isocenter are reallocated from an arbitrary point using DRR (Digitally Reconstructed Radiographs) image in CT Simulation, conventional simulation is normally performed to verify the accuracy of this reallocation of the isocenter through the fluroscopy. The purpose of our experiment is to determine whether repeated test of the verification is necessary or not, and to analyze errors of reallocation with respect to the body region and the beam projection, if necessary, Material and Method : For 200 simulation patient, an arbitrary point is marked on each body and axial scaning is performed using CT, and treatment planing is done by drawing tumor and target volume on each slice. Using the planing data and the reallocated point of the isocenter, DRR image can be obtained and the final isocenter are marked on the patient's skin. In order to verify this reallocation of X,Y.Z coordination from CT simulation, We measure and evaluate the errors of these value on the fluoroscopy monitor and systematize them by classifying according to each body region (Brain, Neck and SCL, Lung, Esophagus, abdomen, Breast and Pelvis) and each beam projection {AP(PA), Supine, Prone and conformal : etc. } Conclusion : Isocenters are shifted by 3-5 mm in the case of Neck & SCL, Breast. at Abdomen, while noticeable differences are not found in other regions. Also, there are not correlations between the errors and the body regions or beam projections. However, our experiment intends to decide whether the procedure of verification is necessary on the vase of time and economy. It is regretful that we could not fully analyze the geometrical errors of DRR image and visual errors from the divergence. In conclusion, according to how much doctor consider tumor margin in drawing tumor and target volume, the meaning of analysis on the reallocation of isocenter should be reinterpreted, (which depends on the experience and capability of doctors)