• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.1662-1667
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• 2005

In this paper, analysis, design, control and prototype construction of a wearable wire-driven haptic interface called HapticPen is discussed. This device can be considered as a wire driven parallel mechanism which three wires are attached to a pen-tip. Wire tensions are provided utilizing three DC servo motors which are attached to a solid frame on the user's body. This device is designed as input as well as output device for a wearable PC. User can write letters or figures on a virtual plate in space. Pen-tip trajectory in space is calculated using motor encoders and force feedback resulting from contact between pen and virtual plate is provided for constraining the pen-tip motion onto the virtual plane that can be easily setup by arbitrary non-collinear three points in space. In this paper kinematic model, workspace analysis, application analysis, control and prototype construction of this device are presented. Preliminary experiments on handwriting in space show feasibility of the proposed device in wearable environments.

• Structural Engineering and Mechanics
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• v.20 no.5
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• pp.559-573
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• 2005

This paper is concerned with the theoretical treatment of transient thermal stresses involving an orthotropic functionally graded thick strip due to nonuniform heat supply in the width direction. The thermal and thermoelastic constants of the strip are assumed to possess orthotropy and vary exponentially in the thickness direction. The transient two-dimensional temperature is analyzed by the methods of Laplace and finite sine transformations. We obtain the exact solution for the simply supported strip under the state of plane strain. Some numerical results for the temperature change, the displacement and the stress distributions are shown in figures. Furthermore, the influence of the orthotropy and nonhomogeneity of the material is investigated.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2008.04a
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• pp.46-49
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• 2008

This paper deals with the free vibrations of elastica shaped arches with constant arc length. The elastica shaped arches are formed by the post-buckled column whose arc length is always constant. The equations governing free, in-plane vibration of general arch in open literature are modified for applying the free vibrations of elastica shaped arch and solved numerically to obtain frequencies and mode shapes for hinged-hinged end constraints. The effects of rotatory inertia, rise to span length ratio and slenderness ratio on natural frequencies are presented. The frequencies of elastica and parabolic shaped arches are compared. Also, typical mode shapes are presented in figures.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.1
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• pp.82-88
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• 2002

This paper deals with the free vibrations of horizontally curved beams with transition curve. Based on the dynamic equilibrium equations of a curved beam element subjected to the stress resultants and inertia forces, the governing differential equations are derived for the out-of-plane vibration of curved beam wish variable curvature. This equations are applied to the beam having transition curve in which the third parabolic curve is chosen in this study. The differential equations are solved by the numerical procedures for calculating the natural frequencies. As the numerical results, the various parametric studies effecting on natural frequencies are investigated and its results are presented in tables and figures. Also the laboratory scaled experiments were conducted for verifying the theories developed herein.

• Journal of the Korean Society for Precision Engineering
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• v.13 no.8
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• pp.60-71
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• 1996

Mostof existing CAD systems do not provide the advanced function for systematic checking of design and drafting errors in mechanical drawings. We have reported a computer aided drawing check system to single plane projection drawings made by a CAD system. This paper describes a checking method of dimensioning errors in mechanical drawings. The checking items are deficiency and redundancy of dimensions, input-errors in dimension figures and symbols, etc. Checking for deficiency and redundancy of global dimensions has been performed applying Graph Theory. This system has been applied to several examples and we have confirmed the feasibility of this checking method.

• School Mathematics
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• v.11 no.2
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• pp.227-241
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• 2009

The isoperimetric problem has been known from the time of antiquity. But the problem was not rigorously solved until Steiner published several proofs in 1841. At the time it stood at the center of controversy between analytic and geometric methods. The geometric approach give us more productive thinking (insight, structural understanding) than the analytic method (using Calculus). The purpose of this paper is to analysis and then to construct the isoperimetric problem which can be applied to the mathematically gifted students in the elementary school. The theoretical backgrounds of our analysis about our problem are based on the Gestalt psychology and mathematical reasoning. Our active program about the isoperimetric problem constructed by the Gestalt's view will contribute to improving a mathematical reasoning and to serving structural (relational) understanding of geometric figures.

• Journal for History of Mathematics
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• v.27 no.2
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• pp.101-110
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• 2014

Joseon is mainly an agricultural country and its main source of national revenue is the farmland tax. Since the beginning of the Joseon dynasty, the assessment and taxation of agricultural land became one of the most important subjects in the national administration. Consequently, the measurement of fields, or the area of various plane figures and curved surfaces is a very much important topic for mathematical officials. Consequently Joseon mathematicians were concerned about the volumes of solids more for those of granaries than those of earthworks. The area and volume together with surveying have been main geometrical subjects in Joseon mathematics as well. In this paper we discuss the history of volumes of solids in Joseon mathematics and the influences of Chinese mathematics on the subject.

• East Asian mathematical journal
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• v.36 no.2
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• pp.131-146
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• 2020

The isoperimetric problem is a well-known optimization problem from ancient Greek. Among plane figures with the same perimeter, which is the largest area surrounded? The answer to the question is circle. Zenodorus and Steiner's pure geometric proofs, which left a lot of achievements in this matter, looked beautiful with ideas at that time. But there was a fatal flaw in the proof. The weakness is related to the existence of the solution. In this paper, from a view of the existence of the solution, we investigate proofs of Zenodorus and Steiner and get educational implications.

• Korean Journal of Veterinary Pathology
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• v.5 no.2
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• pp.71-74
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• 2001

Masses of the uterine cervix were detected from two dogs, being a 2-year-old female Yorkshire tarrier and a 12-year-old female Basset Hound. Grossly, the masses measuring 3.O$\times$3.O$\times$4.0 cm and 12.O$\times$l2.O$\times$10.07m were prominent, sharply circumscribed, fleshy tumors in the uterine cervix. Histologically, the masses consisted of smooth muscle cells interwoven in bundles, some of which were cut longitudinally (elongated nuclei) and others transversely. Tumor cell nuclei were ordinarily cigar shaped and had rounded blunt ends in the longitudinal plane. There were low mitotic figures without abnormal ones. From these results, these cases were diagnosed as leiomyoma of the uterine cervix. To our Knowledge, no similar tumors have been reported in the uterine cervix.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2004.10a
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• pp.13-18
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• 2004

In this study, a new method is proposed generating 3D wire-frames of building using the lowest level topology, points, which are input by human operators. Through the procedure, it is possible to make prediction occlusion points and generate the topology automatically among points, lines, surfaces from buildings. In order to adjust the error of initial values which are input manually, the least squares adjustment for model-image fitting is carried out using the edge information of aerial imagery. And also, model fitting procedure is done making all surfaces plane of buildings by the least squares adjustment. As a result of those procedure, 3D building models are refined similar to real figures of buildings.