• Journal of Electrical Engineering and Technology
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• v.1 no.2
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• pp.246-250
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• 2006

Highly ordered gold nanodot arrays have been successfully obtained by vacuum evaporation using an anodic aluminum oxide (AAO) as a shadow mask. An AAO mask with the thickness of 300 um was prepared through an anodization process. The structure of the nanodot arrays was studied by a field- emission scanning electron microscope (FE-SEM) equipped with an energy dispersive spectrometer (EDS). A tapping mode atomic force microscope (AFM) was employed for studies of height and phase feature. The nanodot arrays were precisely reproduced corresponding to the hexagonal structure of the AAO mask in a large area. In the gold nanodot arrays, the average diameter of dots is approximately the same as the AAO pore size in the range from 70 um to 80 nm and 100 nm center-to-center spacing. EDS analysis indicated that the gold dots were almost entirely consisted of gold, a highly demanded material.

• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.9 no.5
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• pp.58-64
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• 2000

This paper proposes a method for determining optimal EDM parameters based on discharge area from the physical model of a tool electrode. Main parameters, which affect the EDM performance, are peak value of currents, pulse-on time, and pulse-off time. Such parameters are closely dependent on the discharge area in EDM process. In this paper the discharge area is estimated from the CMM scanning data to the tool electrode. The method is very useful when any geometric information to the tool electrode is not provided from tool modeler or producer. The method consists of following four steps. First a triangulation mesh is constructed from the CMM data. Secondly, the z-map is modeled from the triangulated mesh. Thirdly, the discharge area is estimated from intersection between the z-map model and a z-height plane. Finally, the machining parameters are easily calculated by some known EDM equations to the discharge area. An example is introduced to show that the machining parameters are calculated from the CMM data to a tool electrode.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.69-72
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• 2007

Cellulose is a beneficial material that has low cost, lightweight, high compatibility and biodegradability. Recently electroactive paper (EAPap) on cellulose base was discovered as a smart material and actuator through ion migration and piezoelectric effect. Furthermore cellulose has a potentiality to apply the display material, because of its high reflectivity, flexibility and high transmittance. The various shapes and height patterns of the Cellulose acetate (CA) solution, such as circle and honeycomb patterns, were fabricated and observed by field emission scanning electron microscope (FESEM, S4300 Hitachi). The resulting pattern showed uniform size in the large area without defect. After stretching the CA film with saponification process in the sodium methoxide in methanol solution, Most of the compositions become one directional ordered nanofibers below 50nm.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.05a
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• pp.520-523
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• 2002

The o]d technique of sandblasting which has been used for paint or scale removing, deburring, and glass decorating has recently been developed into a powder blasting technique for brittle materials, capable of producing micro structures larger than $100\mu\textrm{m}$. In this study, we investigated the effect of the size of abrasive and the stand-off distance on the machinability of SUS 304. The varying parameters were the impact angle $90^{\circ}$, scanning times of nozzle 10 and the different nozzle height between 70mm and 140mm. The diameter of dot pattern were 0.2mm. The powder were alumina sharp particles, WA #600, #800 and #2000. The blasting pressure of powder at 0.3 Mpa.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.470-473
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• 2005

This paper proposes a reconstruction method for the shape and color information of 3-dimensional buildings. The proposed method is range scanning by laser range finder and image coordinates' color information mapping to laser coordinate by a fixed CCD camera on laser range finder. And we make a 'Far-View' using high-resolution satellite image. The 'Far-View' is created that the height of building using DEM after contours of building extraction. The user select a region of 'Far View' and then, appear detailed 3D-reconstruction of building The outcomes apply to city plan, 3D-environment game and movie background etc.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.2
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• pp.211-219
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• 2000

This paper simulated surface grinding process with statistically simulated grinding wheel topography, considering ridge formation phenomenon when grain scratch workpiece. Wheel grain is modeled as hybrid sphere and cone. Grinding wheel characteristic was evaluated with stylus by expanding the scanning region of the profilometer from a straight line to a plane. Each grain's diameter and semi-angle are assumed as normal distribution, each grain's protrusion height from wheel plane is assumed gamma distribution. So grinding wheel is simulated with grain's position randomly distributed without overlapping. Ground surface is 3-dimensionally simulated considering ridge formation of workpiece by each grain's cutting, and then surface profile and surface roughness parameters are compared with real ground workpiece.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1277-1281
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• 2007

A Nano-tip as a cold field emitter for inducing a field emission current has manufactured in many ways. In the paper, the electrochemical etching method is used. Thus, in order to optimize the final shape as the field emitter, the reliable fabrication system for electrochemical etching was constructed. In addition, the effective parameters such as applied voltage, submerged length, meniscus height, electrolyte concentration and environmental condition(vibration, humidity, cut-off time) have investigated in detail. By controlling the parameters, reliable tungsten tip for field emitter was fabricated. And the fabricated tungsten tip was evaluated optically. Finally, the very sharp apex of the tungsten tip was observed with scanning electron microscope.

• Bulletin of the Korean Space Science Society
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• 2008.10a
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• pp.24.4-25
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• 2008

Limb scanning measurements of the O2 (0-0) Atmospheric band emission by the TIDI instrument aboard the TIMED satellite during 2003-2005 are analyzed to examine the tidal effects on their vertical emission rate according to the solar and geomagnetic activities. The data are restricted at latitudes $60^{\circ}S-60^{\circ}N$ to avoid the contributions by the auroral emission. The variation of the vertical emission rate in latitude and local time is summarized in the yaw periods. The vertical emission profiles of the O2 (0-0) Atmospheric band nightglow averaged in the $10^{\circ}$ latitude range are investigated. The result shows the inverse relationship between the peak emission height and the integrated brightness.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 1992.10a
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• pp.101-105
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• 1992

Machined graphite/epoxy composite surfaces were studied by using SEM(Scanning Electron Microscopy). surface profilometry and its analysis to determine suitable surface describing parameters for machined unidirectional and laminate composite surface. The surface roughness and profile are found to be highly dependent on the fiber layup direction and the measurement direction. Machined unidirectional and 0.deg. 45 .deg. 90 .deg. plies in laminate composite surface profiles are found to be Gaussian in the direction of machining. Since there exist bare fibers without matrix smearing in 0 .deg. ply, higher surface roughness values were found in this orientation. It was possible to machine 90 .deg. and -45 .deg. plies due to the adjacent plies, which were holding those plies. It was found that the microgeometrical variations in terms of roughness parameters Ra without Dy (maximum Damage Depth) region and Dy are better descriptors of the machined laminate composite surface than commonly used roughness parameters Ra and Ra. The characteristics of surface profiles in laminate composite are well represented in CHD (Cumulative Height Distribution) plot and PPD (Percentage Probability Density) plot. Also, the power spectral density function is shown to be capable of identifying the wavelength distribution of the machining damage.

• Journal of the Korean Society for Precision Engineering
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• v.17 no.9
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• pp.166-173
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• 2000

A system for burr measurement is developed to measure the geometry of the burr formed in metal cutting or shearing operations. laser system is selected according to the required measuring accuracy and burr size. A specific program for calculating the burr geometry from measured laser data is developed. The raw data is obtained by scanning cross the burr. The height and width of burr are calculated. Due to the specific characteristic of laser peak or valley are formed in measuring sharp edges or small sharp cracks. Compensation for the peak or valley is carried out to make it possible to calculate the burr, burr geometry is measured in 3 dimension.