• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2010.05a
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• pp.335-338
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• 2010

A recent study for tracing the profiles of supersonic axisymmetric Minimum Length Nozzle with uniform and parallel flow at the exit section, the stagnation temperature is taken into account. The aim of this work is to add optimization algorithm to the supersonic nozzle design in order to get the optimum nozzle shape. The comparisons of the nozzle contours based on the method of characteristics are presented. The specific heats and their ratio vary with the stagnation temperature when this temperature of a perfect gas increases. An application is made for air in a supersonic nozzle.

• Korean Journal of Computational Design and Engineering
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• v.3 no.1
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• pp.15-21
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• 1998

Several adaptive and direct slicing methods have been developed to make the slice data for RP parts with better accuracy and speed. This research deals with a new adaptive slicing algorithm that shows drastic improvement in computing time for calculating the slices of a part. First, it uses less number of sampling points fur each slice in determining the thickness of the next slice. Secondly, the idea of contour map is utilized to determine the optimal sampling point on each slice. Thirdly, the calculation efficiency is further improved by introducing vertical character lines of the given part. The results in terms of accuracy and speed are compared with the existing methods.

• Journal of the Korean Society for Precision Engineering
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• v.25 no.9
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• pp.86-94
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• 2008

A total stroke of an opening or closing motion of a hinge mechanism in a folder-type mobile phone is composed of two portions. In the first portion, human fingers act a force to open or close the folder. In this portion, the rotating folder compresses the coil spring installed in the mechanism. In the last portion, this compressed coil spring generates a torque to rotate the folder. The main merit of this study is that we have designed a hinge mechanism to be operated by a uniform torque in the first portion of the total stroke. The uniform torque means that it is constant along the folder's swing angle. This mechanism will give softer feeling to human fingers. A pair of contours in the mechanism plays an important role. It transforms rotation into translation in the first portion; on the other hand, it transforms translation into rotation in the last portion. In this study, we have developed an algorithm to obtain the pair of contour curves. We divided the total contour curves into finite sub-intervals. Assuming that the curves in every sub-interval are parabolas, we have obtained the coefficients of them by solving systems of nonlinear equations recursively.

• Magazine of the Korean Society of Agricultural Engineers
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• v.45 no.6
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• pp.83-95
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• 2003

In this study, a new concept in a paddy consolidation project is introduced in that curved parallel terracing with contour-lined layout is adopted in sloping areas instead of conventional rectangular terracing. The contoured layout reduces earth-moving considerably compared to rectangular methods in consolidation projects. The objective of the paper is to develop a combinatorial optimization model using the network theory for the design of contour-lined plots which minimizes the volume of earth moving. The results showed that as the length of short side of plot is longer or the land slope is steeper, the volume of earth moving for land leveling increases. The developed optimization model is applied for three consolidated districts and the resulting optimal earth moving is compared with the volume of earth from the conventional method. The shorter is the minimum length of short side of a polt with increases the number of plots, the less is the volume of earth. As the minimum length of short side is 20 m for efficient field works by farm machinery, the volume of earth moving of optimal plot is less by 21.0∼27.1 % than that of the conventional consolidated plots.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.35 no.6
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• pp.669-675
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• 2011

A constant hanger is a device for supporting pipes in plants. It supplies a constant force to a supporting pipe even if the pipe moves because of thermal expansion. In this paper, we propose a method for designing the contour of a cam for a constant hanger. It has been shown that the contour of a cam must satisfy the geometrical relation of the cam, the force balance equation for the load tube, the relation between the side spring compression and the cam rotation angle, and the moment balance equation for the cam. A calculation procedure to solve these equations simultaneously is proposed, and a constant hanger is designed successfully.

• Proceedings of the Korea Society of Design Studies Conference
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• 2002.05b
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• pp.72-73
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• 2002

• Proceedings of the KIEE Conference
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• 2005.10b
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• pp.394-396
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• 2005

In this paper, we propose an adaptive tracking control method of a mobile manipulator for contour following with a kinematic model to have several unknown dimension parameters. Moreover, we will use the decentralized control method to design two independent controllers for two subsystems. The proposed controllers in this paper are based on the Lyapunov function in order to guarantee the stability of whole system for contour following task. The updated laws are also designed to estimated the unknown dimension parameters. Finally, the simulation results are presented to show the validity of the proposed controllers in this paper.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.10 no.6
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• pp.116-125
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• 2001

The comprehensive system analysis for contour milling operation has performed in this study, which combined the each element with proper connectivity into closed loop system, and determined the system response by numerical simulation technique. The obtained simulated results were then compared with the experimental results from the practical points of view, and so forth, the governing equations were formulated into the estimation model, which predicted the total contour machining error within 25% accuracy. Through the procedural evaluation, it could ascertain the characteristics of generation mechan- ifs in circular contour machining error, and the weight of each factor.

• Proceedings of the Korean Society of Agricultural Engineers Conference
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• 2001.10a
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• pp.246-251
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• 2001

This study is aimed to develop system that can export height automatically with Hierarchical Delaunay Triangulation and finally provide profile of hydraulic channel using 3D terrain geometry model. In this study, by using the object-oriented technique, we developed the traverse and cross-section design system of agricultural facilities, which maintain a consistency in the irrigation design process. This system can design the traverse and cross-section profile for the line type facilities. The results of this study, as for the design based on geography, after carrying out the modeling by using TIN of which employs Delaunays algorithm, it was found that the latitudinal design of the facility is feasible. And, as for the formulation of TIN, we obtained more precise result from using contour, stream, and road data rather than using the contour by itself.

• Transactions of Materials Processing
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• v.8 no.5
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• pp.454-464
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• 1999

A new blank design method is proposed to predict the optimum initial blank shape in the sheet metal forming process. The rollback method for blank shape design takes the difference between the deformed blank contour and the target contour shape into account. the minimization object function R is proposed. Based on the method, a computer program composed of blank design module, FE-analysis module and mesh generation module is developed. The rollback method is applied to square cup, reentrant cross section, L-shaped cup drawing process with the flange of uniform size around its periphery to confirm its validity. The optimum initial blank shape is obtained from an arbitrary blank shape after several modifications. Good agreements are recognized between the numerical results and the published experimental results for initial blank shape and thickness strain distribution. It is concluded that the rollback method is an effective and convenient method for an optimum blank shape design.