• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.28 no.8A
• /
• pp.626-632
• /
• 2003

In this paper, forward-wave -3㏈ directional coupler with finite-thickness conductor and asymmetrical coupled lines are designed and experimentally verified using mode-matching based design methodology. Most of studies published in the literatures about the coupled lines are mainly concentrated on the adjustment of coupling amount by changing various geometric configurations. The analysis results in this paper show that thicker metalization requires reduced coupler length in the forward-wave directional coupler composed of asymmetrical coupled lines. Several forward-wave directional -3 ㏈ couplers with finite metalization thickness composed of asymmetrical coupled microstrip lines have been designed in the 5 ㎓ based on proposed design method. The measured data show -4.05㏈∼-4.09㏈ coupling at center frequency which is very closed to design value. The tight coupling has been implemented with accurate design methodology which take mentalization thickness into account.

• Proceedings of the Korean Society of Surveying, Geodesy, Photogrammetry, and Cartography Conference
• /
• 2003.10a
• /
• pp.147-152
• /
• 2003

Aerial Images are usually used to extract 3-D coordinates of various urban features. In this process, the stereo matching of images should be performed precisely to extract these information from aerial Images. In this research, we proposed a matching technique based on geometric features of lanes. We extracted lanes from aerial images and grouped into 4 lane's types. They are lane lines, dotted lines, arrow lane, safety zone. After preprocessing, We will match them by spatial relationships, for example, the distance and orientation between the extracted features. In the future, we will obtain lane coordinates and reconstruct 3-d coordinates of roads.

• 제어로봇시스템학회:학술대회논문집
• /
• 2003.10a
• /
• pp.128-133
• /
• 2003

In this paper, we have proposed a method by using virtual simulation to calculate the behaviors of spacers to avoid conductor galloping with the hanging composite polymer spacer between conductors on different phases. We have considered with three types of modeling considerations for the analysis of galloping in power transmission lines, such as iced-single conductors without spacer, iced-single conductors with spacers, and iced-two bundle conductors with spacers. In simulation, the finite element method is used to calculate the structural response with geometric nonlinear behavior. The iced conductor is modeled by two beam-element faces with which it is connected. The ANSYS program is applied too. First, the calculation results show that the two beam-element model is very suitable to make a virtual simulation. Second, the amplitude of conductor galloping is reduced after hanged spacers. Third, when number of spacer is increased, the maximum magnitude of natural frequency of iced conductor will reduce. Final, the behaviors of spacers are verified in viewpoint of standard cases.

• Journal of the Korean Institute of Telematics and Electronics A
• /
• v.31A no.1
• /
• pp.93-102
• /
• 1994

This paper, presents SECRET(SEC REliability Tool), which predicts reliability problems related to the hot-carrier and electromigration effects on the submicron MOSFETs and interconnections. To simulate DC and AC lifetime for hot-carrier damaged devices, we have developed an accurate substrate current model with the geometric sensitivity, which has been verified over the wide ranges of transistor geometries. A guideline can be provided to design hot-carrier resistant circuits by the analysis of HOREL(HOT-carrier RFsistant Logic) effect, and circuit degradation with respect to physical parameter degradation such as the threshold voltage and the mobility can also be expected. In SECRET, DC and AC MTTF values of metal lines are calculated based on lossy transmission line analysis, and parasitic resistances, inductances and capacitances of metal lines are accurately considered when they operate in the condition of high speed. Also, circuit-level reliability simulation can be applied to the determination of metal line width and-that of optimal capacitor size in substrate bias generation circuit. Experimental results obtained from the several real circuits show that SECERT is very useful to estimate and analyze reliability problems.

• Journal of the Korean Home Economics Association
• /
• v.27 no.2
• /
• pp.31-42
• /
• 1989

The purpose of this study was to develop a computer program to draft princess line onepiece dress pattern. To this study, the Turbo Pascal Compiler and the Pascal language were used. The procedures of the study were as follows: 1. A basic onepiece dress pattern was drafted by the hand operation. 2. The co-ordinate points were instituted for indication of relative position of all necessary points in drafting. Total sixty-nine co-ordinte points (front: thirty-five, back: thirt-four) were instituted. 3. The two subprograms for main program were developed to solve geometric problems and to draft straight lines and curved lines of the onepiece dress pattern. 4. The program was accomplished by putting indivisual body measurement 5. Grading fo five size was given.

• Korean Journal of Computational Design and Engineering
• /
• v.8 no.4
• /
• pp.262-269
• /
• 2003

An approach to compute characteristic curves such as section curves, reflection characteristic lines, and asymptotic curves on a surface is introduced. Each problem is formulated as a surface-plane inter-section problem. A single-valued function that represents the characteristics of a problem constructs a property surface on parametric space. Using a contouring algorithm, the property surface is intersected with a horizontal plane. The solution of the intersection yields a series of points which are mapped into object space to become characteristic curves. The approach proposed in this paper eliminates the use of traditional searching methods or non-linear differential equation solvers. Since the contouring algorithm has been known to be very robust and rapid, most of the problems are solved efficiently in realtime for the purpose of visualization. This approach can be extended to any geometric problem, if used with an appropriate formulation.

• Communications for Statistical Applications and Methods
• /
• v.8 no.2
• /
• pp.565-572
• /
• 2001

This article explores the problem of ergodicity for the nonlinear autoregressive processes with ARCH structure in a very general setting. A sufficient condition for the geometric ergodicity of the model is developed along the lines of Feigin and Tweedie(1985), thereby extending classical results for specific nonlinear time series. The condition suggested is in turn applied to some specific nonlinear time series illustrating that our results extend those in the literature.

• Korean Journal of Mathematics
• /
• v.32 no.2
• /
• pp.259-284
• /
• 2024

In present study, we introduce ruled surfaces whose base curve is the Salkowski curve in Euclidean 3-space and whose generating lines consist of the Frenet vectors of this curve (tangent, principal normal and binormal vectors). Then, we produce regular surfaces from a vector with real coefficients, which is a linear combination of these vectors, and we examine some special cases for these surfaces. Moreover, we present some geometric properties and graphics of all these surfaces.

• Korean Journal of Human Ecology
• /
• v.15 no.2
• /
• pp.303-316
• /
• 2006

The present study deals with developing a new modem design of quilt which is characteristic of Korean traditional patterns. The goal of this study is to make some samples of the pattern as a basic motive of quilt work by using some Korean traditional patterns that could be found in roof tiles, windows, Neung-Hwa (a kind of wood cut for printing book covers), and others. This study examines the concept of quilts, their historical background, and their characteristics. This study also examines traditional patterns that are applicable to the patchy work of quilt, discussing the characteristic of both the Korean patterns and Nubi (Korean traditional quilt). In the process of pattern development, the original patterns were simplified and transformed to apply them to the modem quilt pattern. Fabrics (100% cotton) of similar colors were used to emphasize quilting lines. This study has found followings; 1) The geometric pattern usually consists of dots, lines, and faces. These patterns are suitable for pieced quilts. 2) The curvilinear pattern found in roof tiles or Yi-Dynasty coins, can be easily re-expressed by the applique technique. Combinations of fabrics and motive compositions can express quilts in realistic and creative ways. 3) Addition of Korean traditional quilt techniques, such as parallel lines or swastika stitches, to the traditional object-derived quilt patterns led to the creation of images close to the already existing Korean quilt, Nubi.

• Journal of the Korea Institute of Information and Communication Engineering
• /
• v.10 no.4
• /
• pp.680-686
• /
• 2006

Document images captured by scanners have only skewing distortion. But camera captured document images have not only skew but also vignetting effect and geometric distortion. Vignetting effect, which makes the border areas to be darker than the center of the image, make it difficult to separate characters from the document images. But this effect has being decreased, as the lens manufacturing skill is developed. Geometric distortion, occurred by the mismatch of angle and center position between the document image and the camera, make the shape of characters to be distorted, so that the character recognition is more difficult than the case of using scanner. In this paper, we propose a method that can increase the performance of character recognition by correcting the geometric distortion of document images using a linear approximation which changes the quadrilateral region to the rectangle one. The proposed method also determine the quadrilateral transform region automatically, using the alignment of character lines and the skewed angles of characters located in the edges of each character line. Proposed method, therefore, can correct the geometric distortion without getting positional information from camera.