• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.920-924
• /
• 2002

This paper presents the reverse design of a cam mechanism using NURBS(Nonuniform Rational B-spline curve). Cam is very difficult to make the accurate shape on the design and the manufacture. Because the cam shape is commonly made in order to move in special functions. The reverse design can be used to check accuracy between the designed data and the manufactured data of the cam shape and also reproduce the cam without the design data. The reverse design procedures consist of motion analysis and curve fitting. The motion analysis is used the central difference method and the relative velocity method to find the displacement and velocity. The curve fitting is used NURBS to develope the whole curve. The central difference method is derived in the 3 dimensional space.

• Journal of the Society of Naval Architects of Korea
• /
• v.32 no.2
• /
• pp.1-9
• /
• 1995

This paper suggests a numerical method that creates and varies hull form geometry of underwater vehicle. That is, it induces the cylindrical underwater vehicle from principal dimensions-total length, the length of parallel middle body, the coefficient defining entrance & run parts etc.-and represents using NURBS curve. Also, each section of hull form is varied by user interface and Sectional Area Curve is generated.

• KIEE International Transaction on Electrical Machinery and Energy Conversion Systems
• /
• v.2B no.4
• /
• pp.168-173
• /
• 2002

A new identification algorithm for the Preisach model is presented. The algorithm treats the identification procedure of the Preisach model as an inverse problem where the independent variables are parameters of the distribution function and the objective function is constructed using only the initial magnetization curve or only tile major loop of the hysteresis curve as well as the whole reversal curves. To parameterize the distribution function, the Bezier spline and Gaussian function are used for the coercive and interaction fields axes, respectively. The presented algorithm is applied to the ferrite permanent magnets, and the distribution functions are correctly found from the major loop of the hysteresis curve or the initial magnetization curve.

• International Journal of Aeronautical and Space Sciences
• /
• v.17 no.4
• /
• pp.622-630
• /
• 2016

In the operation of a low earth orbit satellite, a series of antenna commands are transmitted from a ground station to the satellite within a visibility window (i.e., the time period for which an antenna of the satellite is visible from the station) and executed to control the antenna. The window is a limited resource where all data transmission is carried out. Therefore, minimizing the transmission time for the antenna commands by reducing the data size is necessary in order to provide more time for the transmission of other data. In this paper, we propose a geometric compression method based on B-spline curve fitting using dominant points in order to compactly represent the antenna commands. We transform the problem of command size reduction into a geometric problem that is relatively easier to deal with. The command data are interpreted as points in a 2D space. The geometric properties of the data distribution are considered to determine the optimal parameters for a curve approximating the data with sufficient accuracy. Experimental results demonstrate that the proposed method is superior to conventional methods currently used in practice.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2002.10a
• /
• pp.663-666
• /
• 2002

Originally, the thermoforming method has been developed to produce the plastic parts which have simple geometric characteristics such as door trims and wrapping materials within the short time. But the thermoformed parts have non-uniform thickness distributions over the surface according to the material characteristics, set-up angle and geometry of the parts. But, only few analysis methods have been developed so far, due to the difficulties of the selection of important factors, and contribution of each factor in the simulation. So, to guarantee the dimensional accuracy and mechanical properties of crucial points in the thermoformed parts, it is necessary to develop the thickness prediction method. This research suggests a new approaching methodology to predict the thermoformed parts by modulating the control points of the NURBS curve. The newly developed method makes it possible not only to choose the suitable thickness of polymer sheets but also to induce data modification for vacuum forming.

• The Journal of the Institute of Internet, Broadcasting and Communication
• /
• v.17 no.6
• /
• pp.121-126
• /
• 2017

Recently, a lot of people use touch-pen devices such as smart phones and tab computers. To generate the picture and text, a user can give input or control the touch-pen device through simple or multi-touch gestures by touching the screen with a special stylus pen and/or one or more fingers. The accuracy and response time from the moment of contact with the touch board is very important to the touch device. Therefore, research is needed to find a way of removing the noise included in the touch signal quickly and efficiently. In this paper, we propose a method for removing a noise mixed in with a touch point coordinate which has been caused by a input pen on the touch screen. For effective filtering, the fast sampling of the coordinate corresponding to the noise from the input signal is required primarily. Secondly the total compensation of the touch coordinates using the characteristics of the B-Spline curve is applied to correct coordinates of the points. This method can ensure a real-time response than other algorithms. The applied performance evaluation method is comparing error pixels with evaluation values by dividing 10 intervals on the touch pad diagonally. Usually the average error is 7.1 pixels but our proposed method shows an average 4.1 errors. Therefore, our proposed touch pen method can express the input signal on the coordinates more correctly.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2001.04a
• /
• pp.426-429
• /
• 2001

Many various products are manufactured which have sculptured surfaces recently. Constructing surface of these models is required technique called reverse engineering. In reverse engineering, a product which has sculptured surfaces is measured and we create surface model to acquire complete model data of object. Measured point data needs preprocess and sampling. Next a set of point data in a plane fit section curve. At last, surface is generated by fitting to section curves. Here we uses sweep surface. Sweep surface is compatible fitting CAD model to drawing. This paper discusses converting approximation of NURBS surface as a standard surface.

• Journal of the Korean Institute of Intelligent Systems
• /
• v.15 no.1
• /
• pp.110-115
• /
• 2005

This paper proposes the method to detect contours of a face, eyes and a mouth in a color image for making an avatar automatically. First, we use the HSI color model to exclude the effect of various light condition, and we find skin regions in an input image by using the skin color is defined on HS-plane. And then, we use deformable templates and Genetic Algorithm(GA) to detect contours of a face, eyes and a mouth. Deformable templates consist of B-spline curves and control point vectors. Those can represent various shape of a face, eyes and a mouth. And GA is very useful search procedure based on the mechanics of natural selection and natural genetics. Second, an avatar is created automatically by using contours and Fuzzy C-means clustering(FCM). FCM is used to reduce the number of face color As a result, we could create avatars like handmade caricatures which can represent the user's identity, differing from ones generated by the existing methods.

• 제어로봇시스템학회:학술대회논문집
• /
• 2005.06a
• /
• pp.1534-1538
• /
• 2005

In this paper, we propose a method to detect contours of a face, eyes, and a mouth of a person in the color image in order to make an avatar automatically. First, we use the HSI color model to exclude the effect of various light conditions, and find skin regions in the input image by using the skin color defined on HS-plane. And then, we use deformable templates and genetic algorithm (GA) to detect contours of a face, eyes, and a mouth. Deformable templates consist of B-spline curves and control point vectors. Those represent various shapes of a face, eyes and a mouth. GA is a very useful search algorithm based on the principals of natural selection and genetics. Second, the avatar is automatically created by using GA-detected contours and Fuzzy C-Means clustering (FCM). FCM is used to reduce the number of face colors. In result, we could create avatars which look like handmade caricatures representing user's identity. Our approach differs from those generated by existing methods.

• Journal of the Korea Computer Graphics Society
• /
• v.17 no.1
• /
• pp.1-7
• /
• 2011

We present a new technique for constructing a sweep surface using two-parameter motion. Firstly, a new rational B-spline motion with two parameters is introduced, which is obtained by extending its orientation curve and scaling curve to surface counterparts. A sweep surface is then defined by a single vertex v under the two-parameter motion and allows to represent different u-directional iso-curves depending on parameter ${\upsilon}$. Efficient techniques for modeling and editing the surface are achieved by intuitively controlling the two-parameter motion. We demonstrate the effectiveness of our technique with experimental results on modeling and editing a 3D propeller model.