• Journal of the Korean Society of Manufacturing Process Engineers
• /
• v.6 no.4
• /
• pp.71-75
• /
• 2007

Geometrical error of ultra-precision machining due to spherical tool alignment error is analyzed. Deviation of spherical edge, ranged several ten micrometers, generates vertical and horizontal error of tool path and affects profile accuracy of machined surface. Simulation of machined error shows effect of tool alignment error and enables to estimate alignment error. This work provides technical insights into the minimizing of geometrical error of ultra-precision machining.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2004.10a
• /
• pp.1466-1469
• /
• 2004

Micro spherical lens mold processing method based on mechanical one completes a spherical shape by setting a diamond tool of hundreds $\mu$m radius on spins with high speed and then using Z-axis vertical feeding motion like the fabrication of micro drilling. In this method, we can see unprocessed parts shaped like cylinder and cone and check increasing chatter marks and burrs by setting errors of the central axis of rotation on the edge of the tool. That is why this method doesn't suit for the optical lens mold. In this paper presents unprocessed parts are disappeared and chatter marks and burrs are decreased from centre of the lens after using Run-out measuring and setting system on run-out occurred from setting tool. Also the fabrication characteristics of 6：4 Brass, A1601, PMMA are compared and analyzed, establishing the optimum machining condition on each material.

• Journal of Korean Society of Forest Science
• /
• v.86 no.2
• /
• pp.251-258
• /
• 1997

The pollen morphology of 20 species and one variety of the two genera of Hippocastanaceae was investigated by LM, SEM and TEM. The pollen grains of this family are monads, prolate to subprolate, isopolar, radially symmetrical, 3-colporate or 3-colpate and ora is circular or lolongate. Sculpture pattern is distinctly striate or spinulose, Brae in various directions. Based on the aperture types and sculpture patterns three major pollen types of this family are discernible : hippocastanum, indica, and punduana.

• Korean Journal of Plant Taxonomy
• /
• v.37 no.2
• /
• pp.87-108
• /
• 2007

The pollen morphology of 31 taxa, representing all woody species from 12 genera of Fabaceae in Korea, was examined by light microscope and scanning electron microscope. The pollen grains were monad and prolate spheroidal or rarely subprolate in equatorial view. The pollen grain aperture was trizonocolporate or rarely trizonooperculate, which does not occur in the other families of Fabales in Korea. The exine showed a great variety of sculpture pattern, i.e. psilate, microperforate, densely microperforate, perforate, polygonal perforate, macroperforate, macroperforate with granules in holes, polygonal macroperforate, verrucate with pitted perforate striae, verrucate-perforate, granulate, rugulate, reticulate or refined reticulate. The pollen morphological data supported the idea that the genera Echinosophora and Sophora were congeneric. Caragana (Galegeae) was quite close to the Sophora group (Maackia, Sophora and Echinosophora) of the Sophoreae in each measured pollen parameter and exine sculpture pattern. Eleven genera of Fabaceae were recognized based on differences in aperture type, pollen grain shape and exine pattern, and a generic pollen key of the woody Fabaceae in Korea was developed. A key to pollen types of Lespedeza was also suggested. The examined taxa of Coronilla and Wisteria were recognized by their exine patterns.

• Proceedings of the Korean Society of Precision Engineering Conference
• /
• 2001.04a
• /
• pp.950-955
• /
• 2001

For the development of an ultra-precision CNC polishing system including on-machine measurement system, we study a corrective polishing algorithm. We analyze and test the unit removal profiles for a ball type polishing tool. Using these results we calculate dwell time distributions and residual errors for a target removal shape. We use the polishing simulation method and feed rate calculation method for the dwell time calculation. We test corrective polishing algorithm with an optical glass. The target removal shape is a sine wave that has amplitude 0.3 micro meters. We find this polishing process has a machining resolution of nanometer order and is effective for sub-micrometer order machining. This result will be used for the software development of the CNC polishing system.

• Korean Journal of Plant Taxonomy
• /
• v.45 no.4
• /
• pp.323-331
• /
• 2015

Pollen morphological characteristics of 7 taxa of the genus Aruncus L. (Rosaceae) were examined using scanning electron microscopy (SEM) to evaluate the taxonomic implication within the genus. Aruncus pollen grains were monad, tri-colporate with granular membranes, small in size ($P=8.33-12.57{\mu}m$, $E=8.93-14.40{\mu}m$), amb is sub-circular to circular, suboblate to prolate-spheroidal in shape (P/E = 0.68-1.70). The sexine ornamentation in all studied taxa was basically striate but existence of perforation (striate-perforate: A. dioicus, A. dioicus var. acuminatus, A. dioicus var. astilboides, A. dioicus var. pubescens, A. dioicus var. vulgaris; striate-pstilate: A. dioicus var. aethusifolius, A. gombalanus) and the widths of muri and grooves varied according to the taxa. In particular, relatively short, and sharply crested muri being a distinct feature of A. dioicus var. acuminatus. As a result, the various combination of each pollen characteristics could be useful to identify the some taxa of the genus Aruncus.

• Korean Journal of Plant Taxonomy
• /
• v.41 no.2
• /
• pp.108-112
• /
• 2011

The pollen of 5 taxa on Korean Oldenlandia L. was investigated by LM and SEM. The pollen grains were monads, $20.7-36.0{\mu}$m in polar length, with an equatorial diameter of $21.0-38.4{\mu}m$. The pollen shapes were oblate-spheroidal or spherical (P/E ratio 0.93-1.00). The apertures numbered 3-7 in number, colporate in shape, with a colpus length of $4.2-20.4{\mu}m$ and a colpus width of $2.6-3.4{\mu}m$. The sexine was $0.9-2.4{\mu}m$ in terms of its thickness, the surface pattern was reticulate, scabrate or neither. Based on these results, the size of the pollen grain, the number of apertures, and the surface pattern of the sexine were all useful for an interspecific classification. The genus Neanotis, established via the pollen characteristics, was thought to be reviewed in its entity regarding the continuous variation of generic characteristics.

• Journal of IKEEE
• /
• v.23 no.4
• /
• pp.1387-1392
• /
• 2019

Aspherical mirrors have lighter weight and better performance than spherical mirrors, but it is difficult to process their shape and measure the processing precision. Especially, large aperture aspherical mirrors mounted on satellites need high processing precision and long processing time. The computerized numerically controlled machine of gantry type has been used in polishing process, but it has difficulties in processing the complex shapes due to the lack of degrees of freedom. In order to overcome this problem we developed a polishing system using an articulated industrial robot. The system consists of tool path generating program, real-time robot monitoring, and control program. We show the performance of the developed system through the computer simulation and actual robot operation.

• Journal of Korean Society of Forest Science
• /
• v.55 no.1
• /
• pp.1-21
• /
• 1982

The pollen morphology of 2 forms, 6 varieties, 50 species, 15 genera, 11 families of Korean Sapindales was studied. The keys were provided for general and families of Korean Sapindales. General pollen morphology was diversed and taxonomically significant differences were obtained in shape, aperture, type and size, sculpture pattern and exine thickness of pollen grains. Pollen grains of Korean Sapindales could be grouped into four types and five subtypes. One of five sub-types pollen grains of Acer could be ground into four under subtypes: ginnala type, barbinerve type, psseudo-sieboldianum type and negundo type. Pollen morphology of Empetraceae, Buxaceae and Balsaminaceae appeared to have very special features in the equatorial view and aperature type compare with pollen grain of the other families of Korean Sapindales.

• Journal of Korean Society of Forest Science
• /
• v.85 no.3
• /
• pp.472-486
• /
• 1996

The pollen morphology of 19 species and 1 variety of the genus Acer L. in Korea was investigated by light and scanning electron microscopy. The results are as follows ; 1. A. pollen key of the genus Acer L. in Korea was provided in four types. 2. Based on the aperture types and sculpture patterns, the four major pollen types of the genus Acer L. in Korea were recognized which included palmatum, barbinerve, negundo and saccharum types. 3. Pollen grains are tricolpate or tricolporate on the aperture, and striate, rugulate or reticulate on the sculpture pattern. 4. As the result of the correlation analysis between the five measured pollen parameters in pairs, a highly significant positive correlation was found between polar axis length(PL) and colpus length (CL).