• Journal of Korean Ophthalmic Optics Society
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• v.20 no.3
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• pp.349-354
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• 2015

Purpose: To investigate the changes of corrective values of astigmatism caused by the position of circle of least confusion on retina in refining astigmatic test using cross cylinder. Methods: 62 subjects (115 eyes) aged $22.24{\pm}2.48$ years participated for this study. After astigmatic test using a radial chart, refining test was performed using a cross cylinder in a condition of maximum plus to maximum visual acuity (MPMVA). Astigmatic refining test was repeatedly performed in each condition of which S+0.75 D, S+0.50 D, S+0.25 D, S-0.25 D, S-0.50 D, and S-0.75 D are added to spherical lenses of MPMVA. The measured values were compared with the values in MPMVA condition. Results: As compared with values in condition of MPMVA, change of astigmatic axis was increased with add the power of (+) spherical lenses and (-) spherical lenses. In same spherical condition, change of astigmatic axis was decreased with increment of astigmatic power (p<0.05). The corrective power of astigmatism was reduced with increment of (+) spherical lenses (p<0.05), and was raised with increment of (-) spherical lenses compared with the power in MPMVA condition. In case of adding (+) spherical lenses, difference of astigmatic power increased with increment of corrective astigmatism power in same test condition. Conclusions: In order to obtain a proper values for corrective astigmatism, position of circle of least confusion should be accurately adjusted before the performing an astigmatism's refining test.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.6
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• pp.1004-1014
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• 2001

The fully automatic algorithm from initial finite element mesh generation to remeshing in two dimensional geometry is introduced using bubble packing method (BPM) for finite element analysis. BPM determines the node placement by force-balancing configuration of bubbles and the triangular meshes are made by Delaunay triangulation with advancing front concept. In BPM, we suggest two node-search algorithms and the adaptive/recursive bubble controls to search the optimal nodal position. To use the automatically generated mesh information in FEA, the new enhanced bandwidth minimization scheme with high efficiency in CPU time is developed. In the remeshing stage, the mesh refinement is incorporated by the control of bubble size using two parameters. And Superconvergent Patch Recovery (SPR) technique is used for error estimation. To verify the capability of this algorithm, we consider two elasticity problems, one is the bending problem of short cantilever beam and the tension problem of infinite plate with hole. The numerical results indicate that the algorithm by BPM is able to refine the mesh based on a posteriori error and control the mesh size easily by two parameters.

• Korean Journal of Heritage: History & Science
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• v.54 no.3
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• pp.52-67
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• 2021

This study is an attempt to explore the roles of and the collaborative relationship between Daheojang and Maedeupjang. Daheojang and Maedeupjang share a similar manufacturing process. However, in modern times, Daheojang totally disappeared, and Maedeupjang was designated as an intangible cultural property. The present study will investigate the role of Daheojang and Maedeupjang based on the literature of the Joseon dynasty. Daheojang were craftsmen who made bands and strings of woven or twisted silk strands. They made mangsu and tassels or made knots to produce magnificent artifacts. Maedeupjang complete all steps of the process, from refining, dyeing, combining threads, daheo, maedeup, to the tassel. Daheojang in the Joseon dynasty was the center of this process. Daheojang belonged to almost all Uigwe because it used items ranging from large uso to cushion straps. Dahoe is a craft with various items and techniques. It has been widely used to produce majestic items like formal dresses, ritual ceremony pieces, and mountings, as well as daily items like jodae, pocket straps, and norigae. Based on the records of Uigwe in the late Joseon dynasty, the study explored the collaborative relationship between Daheojang and Maedeupjang. Sambang, the room where both Daheojang and Maedeupjang belong, was the room to produce the royal chair. The royal chair essentially includes large uso. The large uso is an artifact that ties a knot in a thick circle more than two meters long. While Daheojang made rounded daheo, Maedeupjang made delicate and balanced knots. Also, they produced royal inscriptions together with a royal seal with decorative mangsu and a seal of thick rounded daheo. In order to learn about traditional technology, it is necessary to study the system of the times and social trends. Therefore, the study focused on Daheojang, who were common master craftsmen during the Joseon dynasty but now are not familiar to most people.