• Conservation Science in Museum
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• v.17
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• pp.55-68
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• 2016

Conservation and research efforts are currently underway at the National Museum of Korea on a series of artifacts excavated from Tomb No. 9 at Seogam-ri nearly a century ago by an archaeology team from the institution's colonialera predecessor. Among these objects are a number of bronze and gilt bronze buttons. The present study explores the production techniques used in making such buttons. Both bronze and gilt bronze buttons are hemispherical in shape and are similar in external appearance. However, their shanks differ significantly in size and cross-sectional shape, some with a round cross-section while others are square. The buttons, first sorted into two groups by each type of shank, were further subdivided by size. Analysis of round shanks has found variations in design and location as well as in shank thickness. In addition, the location where round shanks attach to buttons are usually irregular in surface. Square shanks, on the other hand, are more uniform in design and location. The shanks are typically located on the backs of buttons and attach to a groove which ostensibly serves to mark the correct position. X-ray imaging has revealed that round shanks have thick borders made from metal rather than dirt or other material. The buttons themselves appear to been cast using lost-wax technique. The ways in which each shank attaches to its respective button varies based on its cross-sectional shape.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.31 no.2
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• pp.70-76
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• 1999

This study was to measure the potential of nonwoody fibrous material, kenaf. Whole stalk of kenaf, Hibiscus cannabinus was separated by two parts of bast and core portion, and cooked separately by alkaline method. Morphological characteristic was evaluated using confocal laser scanning microscope (CLSM) and fiber quality analyzer(FQA). The strength properties of handsheets, made by different mixing ration between kenaf base and core fibers, were measured. Cross-sectional area of bast fibers was smaller than that of core fibers, but the bast fibers had a thick cell wall and narrow lumen area. Bast fibers were longer in length than core fibers. Core fibers had thin cell walls, broad lumen areas, and short lengths, and they had collapsed shape even in water. These characteristics of core fibers affected strength properties of handsheet positively. When the amount of core fibers increased, the strength properties of handsheet were increased. When the amount of bast fibers increased, the handsheet had rougher surface and higher air permeability.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.4_1
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• pp.529-536
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• 2023

In this study, the spur gear with honeycomb lattice structures are designed. The pitch diameter and body length of the spur gear are Ø93 mm and 104.0 mm, respectively. The designed gear was printed using Powder bed fusion (PBF) 3D printer. The gear is 3D printed perfectly. Even the teeth and honeycombs of the gear were output in the same way as the design shape. The printed gear with honeycomb lattice structure has a 24% smaller cross-sectional area and 29% smaller volume and weight than conventional solid structure gears. The surface roughness is approximately 4.5㎛, and the hardness is 345 HV.

• 제어로봇시스템학회:학술대회논문집
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• 2001.10a
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• pp.131.5-131
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• 2001

A new measurement method to measure vibrational motions of objects is presented. The original principle is similar to the previous work that utilized a 3-facet mirror to obtain three dimensional positions and orientations of rigid bodies. While the previous work was presented for only stationary objects, in this paper, we newly investigate the feasibility of this method for dynamic applications. The 3-facet mirror that looks like a triangular pyramid having an equilateral cross-sectional shape. The mirror has three lateral reflective surfaces inclined 45 degrees to its bottom surface, and its mounted on the object whose motion is to be measured, As optical components, a He-Ne laser source and three position-sensitive detectors(PSD) are used. The laser beam is emitted from the He-Ne laser source located at the upright position and vertically incident to the top of the 3-facet ...

• 제어로봇시스템학회:학술대회논문집
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• 2002.10a
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• pp.97.5-97
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• 2002

A sensor modeling via artificial neural network is presented in this paper. The optical sensor has been designed to treasure absolute 3-dimensional positions and orientations of objects in 6-DOF. The method utilizes a triangular pyramidal mirror having an equilateral cross-sectional shape referred as 3-facet mirror. The mirror has three lateral reflective surfaces inclined 45 degrees to its bottom surface. The 3-facet mirror is mounted on the object whose 6-DOF motion is to be measured. As optical components, a He-Ne laser source and three position-sensitive detectors(PSD) are used. The laser beam is emitted from the He-Ne laser source located at the upright position and vertically incident o...

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2006.05a
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• pp.659-660
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• 2006

High-aspect-ratio(max. 12.5) microchannels with excellent surface quality and good shape uniformity have been realized utilizing laser-induced etching technique. Etch width and depth variations depend largely upon process variables such as laser power and etchant concentration. Etchant concentration in association with viscosity also influence on the cross-sectional profile of the channels. The optimum process conditions for the fabrication of high-aspect-ratio microchannels applicable to micro thermal devices are demonstrated.

• Laser Solutions
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• v.6 no.3
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• pp.19-28
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• 2003

The manufacturing process for the microfluidic device can include sequential steps such as master fabrication, electroforming, and injection molding. The laser ablation, using masks, has been applied to the fabrication of channels in microfluidic devices. In this research, an excimer laser was used to engrave microscopic channels on the surface of PET (polyethylene terephthalate), which shows a high absorption ratio for an excimer laser beam with a wavelength of 248 m. When 50-${\mu}{\textrm}{m}$-wide rectangular microscopic channels are ablated with a 500 ${\times}$ 500 ${\mu}{\textrm}{m}$ square mask at a magnification ratio of 1/10, ditch-shaped defects were found in both corners. The measurement of laser beam intensity showed that a coherent image in the PET target caused such defects. Analysis based on the Fourier diffraction theory enabled the prediction of the coherent shape at the image surface as well as the diffraction beam shape between the mask and the image surface. It also showed that the diameter of the aperture had a dominant effect. The application of aperture with a diameter of less than 3 mm helped to eliminate such defects in the ablated rectangular microscopic channels on PET without such ditch-shaped defects.

• Korean Journal of Metals and Materials
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• v.48 no.1
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• pp.90-100
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• 2010

Micro-conductive patterns were microfabricated on an insulating substrate ($SiO_2$) surface by a selective electroless nickel plating process in order to investigate the formation of seed layers. To fabricate micro-conductive patterns, a thin layer of metal (Cu.Cr) was deposited in the desired micropattern using laser-induced forward transfer (LIFT). and above this layer, a second layer was plated by selective electroless plating. The LIFT process. which was carried out in multi-scan mode, was used to fabricate micro-conductive patterns via electroless nickel plating. This method helps to improve the deposition process for forming seed patterns on the insulating substrate surface and the electrical conductivity of the resulting patterns. This study analyzes the effect of seed pattern formation by LIFT and key parameters in electroless nickel plating during micro-conductive pattern fabrication. The effects of the process variables on the cross-sectional shape and surface quality of the deposited patterns are examined using field emission scanning electron microscopy (FE-SEM) and an optical microscope.

• Corrosion Science and Technology
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• v.20 no.3
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• pp.105-111
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• 2021

In oxidizing nitric acid solutions, stainless steel undergoes intergranular corrosion accompanied by grain dropping and changes in the corrosion rate. For the safe operation of reprocessing plants, this mechanism should be understood. In this study, we constructed a three-dimensional computational model using a cellular automata method to simulate the intergranular corrosion propagation of stainless steel. The computational model was constructed of three types of cells: grain (bulk), grain boundary (GB), and solution cells. Model simulations verified the relationship between surface roughness during corrosion and dispersion of the dissolution rate of the GB. The relationship was investigated by simulation applying a constant dissolution rate and a distributed dissolution rate of the GB cells. The distribution of the dissolution rate of the GB cells was derived from the intergranular corrosion depth obtained by corrosion tests. The constant dissolution rate of the GB was derived from the average dissolution rate. Surface roughness calculated by the distributed dissolution rates of the GBs of the model was greater than the constant dissolution rates of the GBs. The cross-sectional images obtained were comparable to the corrosion test results. These results indicate that the surface roughness during corrosion is associated with the distribution of the corrosion rate.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.5 no.1
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• pp.44-49
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• 1995

Abstract The surface of 6H - SiC bulk crystal grown by sublimation process was investigated by optical microscope observation. Since, in the 6H crystal growing, the crystal had the habitual step growth attitude such that the lateral growth rate along the random a - axis orientation was higher than that along the c - axis of the growth direction, then many steps were developed. There were, also, many micropipes on the surface in the form of as-like large voids. However, they were differenciated with pores and cross- sectional shape of them were close to the circle. In this study, many micropipes, planar defects and the growth steps appeared on the grown crystal surface were investigated.