• Journal of the Korean Society for Advanced Composite Structures
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• v.3 no.1
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• pp.16-20
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• 2012

During construction of the cable-stayed bridge, not only shape of deck and pylon but also cable forces are main factors for geometry control. Especially, geometry control of deck must be controlled for adjusting design value of vertical and lateral alignment as well as closing of key segment. Also, both the deck level error and cable force error occur necessarily during the construction stage in cable stayed bridge. The errors are caused by different of material properties and computer modeling, and construction mistake, and so on. These causes bring about that the forces of cable and the displacement of deck show different tendency from the theoretical values. Therefore, these errors must necessarily be adjusted and can be improved through adjustment of cable length. In this study, a new optimization tool is proposed to adjust the errors of the second Dolsan cable-stayed bridge.

• Journal of the Institute of Electronics and Information Engineers
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• v.51 no.9
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• pp.208-214
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• 2014

Vehicle dynamic states used in various advanced driving safety systems are influenced by road geometry. Among the road geometry information, the vehicle pitch angle influenced by road slope and acceleration-deceleration is essential parameter used in pose estimation including the navigation system, advanced adaptive cruise control and others on sag road. Although the road slope data is essential parameter, the method measuring the parameter is not commercialized. The digital map including the road geometry data and high-precision DGPS system such as DGPS(Differential Global Positioning System) based RTK(Real-Time Kinematics) are used unusually. In this paper, low-cost cascade extended Kalman filter(CEKF) based road slope estimation method is proposed. It use cascade two EKFs. The EKFs use several measured vehicle states such as yaw rate, longitudinal acceleration, lateral acceleration and wheel speed of the rear tires and 3 D.O.F(Degree Of Freedom) vehicle dynamics model. The performance of proposed estimation algorithm is evaluated by simulation based on Carsim dynamics tool and T-car based experiment.

• Journal of Navigation and Port Research
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• v.29 no.8 s.104
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• pp.763-770
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• 2005

Global Navigation Satellite System (GNSS) has become an indispensable tool for providing precise position, velocity and time information for many applications like traditional surveying and navigation etc. However, Global Positioning System (GPS), which was developed and is maintained and operated by the U.S. Department of Defence (DoD), has monopolized the world industry and market, and hence there exists the situation that most of GNSS users absolutely depend upon the GPS. In order to overcome the monopoly, some countries, such as Russia, Japan and European Union (EU), have developed their own GNSSs, so-called GLONASS, JRANS and Galileo systems. Among them, the most prospective system in near future is EU's Galileo system scheduled to launch in 2008. This research has focused on the next generation GNSS system based on GPS and Gralileo system with developing a GNSS simulation software, named as GIMS2005, which generates and analyzes satellite constellation and measurements. Based on the software, a variety of simulation tests have been carried out to recognize limits of GPS-only system and potential benefits of integrated GPS/Galileo positioning. Geometry simulation results have showed that comparing with GPS-only case, the number qf visual satellites, Dilution of Precision (DOP) values, internal reliabilities and external reliabilities.

• Communications of Mathematical Education
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• v.27 no.3
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• pp.341-356
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• 2013

This research is about storytelling in middle school geometry. This study is basic research about actualizing mathematical teaching and learning based on storytelling that is raised for reforming school mathematics education. In order to develop the mathematics textbook model, development of procedures and methods were extracted from the literature. And mathematics textbook model were developed in accordance with the process and methods. Examples are presented in terms of the development of material with 'story as a communication tool', 'familiar story as a script' 'universality of the world or simulation of life as a story', 'story as a means to foster creativity: story making'. Through the results of this study, we are also able to check the possibility of storytelling in mathematics class. And this study will be the foundation for teaching and learning using storytelling.

• The Journal of Korean Association of Computer Education
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• v.4 no.1
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• pp.99-107
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• 2001

One of the main objects of geometry in mathematics education is to improve students' geometric intuition capability and logical reasoning capability based on them. A visual element related to intuition plays an important role in teaching and learning of geometry. Therefore, in this research, we focus on the development of multimedia title available to dynamic operation about visual elements and verify of effect of its application. This title for the learning of "the Pythagorean theorem and its practical use" in the third grade of middle school is designed and implemented by an authoring tool, Toolbook. And it enables learners to study mathematics individually and can be applied to the educational field, too. And we taught two groups, the applied group and the compared one of the second grade of middle school and surveyed Questions and evaluated study achievement. We calculated study achievement of two groups on t-test using SPSS. As the result, we knew that the applied group is higher than the compared one in the study achievement and provision of dynamic operation possibility on visual elements make students know very high learning effect and help improvement of intelligent capability.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.3
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• pp.433-442
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• 1989

Owing to the development of CNC machine tools and automatic programing software, the milling process with ball-end mill has become the most widely used process where three-dimensional precision machining is important. In this study, the ball-end milling process has been analyzed and a cutting force model has been developed to predict the cutting force acting on the ball-end mill on given machining conditions. The development of the model is based on the analysis of geometry of a ball-end mill an the oblique cutting process. The cutting edges of ball-end mills are considered as a series of infinitesimal elements and the geometry of the cutting edge element each cutting edge element is straight. The oblique cutting process in the small cutting edge element has been analyzed as orthogonal cutting process in the plane containing the cutting velocity vector and chip-flow vector. Hence, with the orthogonal cutting data obtained from orthogonal turning test, the cutting forces can be predicted through the model. The predicted cutting forces has shown a fairly good agreement with the test results in various plane cutting conditions.

• The Journal of the Korea Contents Association
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• v.17 no.6
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• pp.71-80
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• 2017

The standards for achievement levels for building blocks in elementary geometry class is to enhance spatial cognitive ability through practices describing shape patterns of building blocks observed from different directions. However, most of building block in the textbook is described from only one perspective. Even worse, some examples in the textbook are almost impossible to observe in the real world. Contrary to this, simulated views by Wings3D has shown that each box may look quite differently from different angles let alone the size of each box. Using Wings3D, it is also very easy to build different types of building blocks with various levels of difficulty in the virtual space. Based on these results, in this study, 3D visualization SW is suggested as a potential pedagogical tool for the elementary geometry class to help kids perceive objects in space more precisely. We have shown that 3D visualization SW such as Wings3D could be a powerful, compact 3D SW for most of subjects which are covered in elementary geometry education. Wings3D has another advantage of economic open source SW fully compatible with school PCs.

• Journal of Welding and Joining
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• v.29 no.6
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• pp.56-64
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• 2011

Friction stir spot welding between 5454 aluminum alloy sheets with the different thicknesses of 1.4 and 1.0 mm was performed. In the welding process, the tool for welding was rotated ranging from 500 to 2500, and plunged to the depth of 1.8 mm under a constant tool plunge speed of 100 mm/min. And then, the rotating tool was maintained at the plunge depth during the dwell time ranging from 0 to 7 sec. The pull-out speed of the rotating tool was 100 mm/min. The increase of tool rotation speed resulted in the change of the macrostructure of friction-stir-spot-welded zone, especially the geometry of welding interface. The results of the tensile shear test showed that the total displacement and toughness of the welds were increased with the increase of the tool rotation speed, although the maximum tensile shear load was decreased. However, the change in the dwell time at the plunge depth of the tool did not produce the remarkable variation in the macrostructure and mechanical properties of the welds. In all cases, the average hardness in friction-stir-spot-welded zone was higher than that of the base metal zone. By the friction stir spot welding technique, the welds with the excellent mechanical properties than the mechanically-clinched joints could be obtained.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.3
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• pp.151-158
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• 2002

Automotive engineers involved in a new car project use various CAD systems that are chosen based on work requirements. For example, engineers in Hyundai Motors are using Pro/Designer and Alias fur the style design, but they use CATIA to design parts and assemblies, ANSYS for FEM analysis, and Pro/Engineer to design engines. Because they use different CAD systems, they have difficulties in collaborative design. Data, which contains errors, is transferred between CAD systems. It is difficult to find out such errors in a large CAD model. An evaluation method for CAD models has been developed in this study. This diagnosis tool analyses a STEP or an IGES file generated from a CAD system, and produces a quantitative error report. The tool has been tested with actual data sets. This paper proposes an algorithm that produces mathematical error values of entities of IGES models that have geometrical data, and entities of STEP models that have topological data, and inspects every part off model. To develop this system, we have used the OpenCASCADE kernel, which is an open source kernel developed by Matra Datavision of France.

• Proceedings of the KSRS Conference
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• 1999.11a
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• pp.188-193
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• 1999

Technology of GIS evolved as a means of assembling and analyzing diverse spatial data. Many systems have been developed, and almost of systems are proprietary. There is a lots of lack of interoperability and reusability between them. This paper describes the development of Open GIS component software. The developing system have an end in view of GIS tool software which is interoperable and reusable. To increase the interoperability and reusability, the system is based on the OGC(Open GIS Consortium)'s Open GIS Simple Features Specification for OLE/COM. The OGC's specification is announced to increasing the full interoperability of various geospatial data and geoprocessing resources. With the Open specification, component based software ensures the reusability. We implement three kinds of component: Geometry component, Spatial Reference System Component, and MapBase Component. The first two components are compatible to the OGC's specification and the third one is designed to GIS tool software for variant GIS applications. The Open GIS component software system is developed on object-oriented computing environment, ATL/COM and Visual C++. As we made application programs using Visual Basic, the advantages of component based Open GIS software was proved.