• Journal of Ocean Engineering and Technology
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• v.18 no.4 s.59
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• pp.59-64
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• 2004

Functional requirements and design parameters were not clarified in the early design process. Design axiom shows some difficulty for larger system designs, such as the butterfly valve, which is basically carried out by an incremental and iterative process. A numerical analysis was carried out on fluid flows in a butterfly valve, by using ANSYS-FLOTRAN. Characteristics of the butterfly flows at different valve disk opening angles, with a uniform incoming velocity, were investigated. The entire analysis is decomposed to satisfy the independence axiom. This paper resolves the problems associated with the establishment of a systematic design process.

• Journal of the Korean Institute of Educational Facilities
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• v.20 no.6
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• pp.41-48
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• 2013

Elementary school education in Korea has been constantly changing according to the requirements of social change. Contemporary primary education is oriented creative-education and institutional changes were required. As a result, it is appearing movement wants to get out of uniform curriculum of elementary school. This paper was carried out to analyze after-school programs other than the curriculum of elementary education school and to analyze the current status of the space use of school facilities. Based on this analysis, it is proposed utilization of spatial association between the elementary school and local public facilities.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.393-394
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• 2006

Highly compressible Ni-Mo steels are attractive materials for PM due to high sinter density and ease of processing. Extra-fine Ni admixed PM steels have demonstrated improved mechanical properties and rolling contact fatigue resistance due to a more uniform microstructure and increased Ni diffusion during sintering. Sinter densities of single press single sinter XF Ni-Mo steels can approach $7.5\;g/cm^3$ at moderate compaction pressures. Leaner alloys based on extra-fine Ni powder are possible depending on the performance requirements of the PM steel part. Extra-fine Ni steels are particularly attractive for the growing market of high performance PM gears and sprockets.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.4
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• pp.86-93
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• 2003

These days, automobile industry pays considerable attention to child occupant safety. As the US adopted requirements for universal and uniform anchor systems for child restraints, manufacturers for child seats put an enormous effort to improve the protective properties of Child Restraint System (CRS). Various standards have been studied and announced by different countries. The anchorage system is the most important in the CRS and the rules of universal anchor are to provide devices which are independent of safety belts. A new concept called International Standard Organization Fixture (ISOFIX) has been announced. It suggests some designs for the CRS. In this study, the suggested designs are evaluated with domestic products. Tests are performed and the results are incorporated into a finite element modeling process. As the finite element model is established, various numerical tests are conducted and the numerical results are discussed. A commercial software system is utilized for the nonlinear finite element analysis.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.687-690
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• 2004

The preparation of A1203-SiO2 thin films from less than one micron to several tens of microns in thickness had been Prepared from metal alkoxide sols. Two methods, dip-withdrawal and electrophoretic deposition, were employed for thin films and sheets formation. The requirements to be satisfied by the solution for preparing uniform and strong films and by the factors affecting thickness and other properties of the films were examined. For the preparation of thin, continuous A12O3-SiO2 films, therefore, metal-organic-derived precursor solutions contained Si and Al in a chemically polymerized form has been developed and produced in a clear liquid state.

• Proceedings of the KSRS Conference
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• 2003.11a
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• pp.1371-1373
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• 2003

The importance of Fundamental Geographical Information Framework for Digital City (FGFDC) is analysed, it provides all city agencies and units with uniform geographic references. Six kind of data are chosen as the core data sets of a FGDC, a web-based distributed mechanism is constructed to promote data sharing among different agencies. Elementary functional requirements of FGDC are analyzed, so that it can serve as a common distributed urban GIS. A practical FGFDC is developed for Yangzhou Development Administrative Region, and an 3D visualization system is developed within this framework.

• Transactions of Materials Processing
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• v.3 no.3
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• pp.359-374
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• 1994

Process sequence design in sheet metal forming process by the finite element method is investigated. The forming of sheet metal into a washing machine container is used to demonstrate the design of an improved process sequence which has fewer operations. The design procedure makes extensive use of the finite element method which has simulation capabilities of elastic-plastic modeling. A one-stage process to make an initial blank to the final product is simulated to obtain information on metal flow requirements. Loading simulation for a conventional method is also performed to evaluate the design criteria which are uniform thickness distribution around the finished part and maximum punch load within limit of available press capacity. The newly designed sequence has two forming operations and can achieve net-shape manufacturing, while the conventional process sequence has three forming operations. This specific case conventional process sequence has three forming operations. This specific case can be considered for application of the method and for development of the sequence design methodology in general.

• Transactions of Materials Processing
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• v.5 no.2
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• pp.115-121
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• 1996

Recently it is attempted to manufacture gears by various cold forging methods to meet requirements of mass production and uniform qualities. Compared to machined gears cold forged ears reveal higher tooth strength and better surface roughness but they reveal lower geometrical accuracies. Therefore in the present study a series of experiments are performed to investigate relations between geometrical accuracies of dies and billet and those of the final product. The geometrical accuracies of forged gears are considered through functional gear-element tolerances by measuring pitch error profile error lead error radial error tooth thickness and rolling test. Results of the experiments can be summarized as follows: (1) involute spur gears of KS 5(or AGMA7) accuracies can be made,(2) concentricity of die set should be maintained within 0.01mm (3) clearance between the billet and die set should be less than 0.1mm (4) con-centricity and radial runout should be less than 0.08mm and 0.1mm respectively. However it is thought that FEM analysis of elastic/thermal deformations of dies and the billet is necessary for a better understanding of the findings obtained through the present study.

• Proceedings of the KWS Conference
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• 2001.10a
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• pp.121-124
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• 2001

The main characteristic of the Electron Beam Welding technique is its high energy density which produces thin and deep welds with very little distortion. High accelerated electrons, focused in a beam of 0.5 ∼ 2mm diameter, produce narrow welds with deep penetration. The result is a small HAZ as well as a low and uniform distortion which is predictible within very narrow limits. But the small diameter of the EB increases the requirements for the equipment control system for centering the beam on the welding joint in order to avoid any lack of fusion. Therefore, in this paper, we introduce the system developed at our company and the quality of welding zone, the detail function of system.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.5
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• pp.174-181
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• 2004

This paper presents the development of a magnetostrictive microactuator. The structural and functional requirements are as follows: it must be a millimeter structure and must achieve controllable displacement with nanometer resolution. Finite Element Analysis(FEA) is used to determine the structure with the most uniform and highest magnetic flux density along the Terfenol-D rod. The microactuator prototype 1 is designed and made based on the FEA. It is observed that the microactuator show some level of hysteresis and that it produces 25 newton in force and 3 ${\mu}{\textrm}{m}$ in displacement with 1.5 amperes of current, and resolution of 250 nm per 0.1 amperes. To improve the performance of the microactuator prototype 1, microactuator prototype 2 is made again with a permanent magnet (PM). It is observed that the microactuator prototype 2 gene.ates 3.3 ${\mu}{\textrm}{m}$ in displacement with 0.9 amperes of current. It means that the microactuator prototype 2 performs better than the microactuator prototype 1.