• 제어로봇시스템학회:학술대회논문집
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• 2000.10a
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• pp.83-83
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• 2000

Recently, Vision system has being used all around industry. Sensor systems are used for Mark Reader, for example, optical scanning is proximity sensor system, have many disadvantages, such as, lacking user interface and difficulty to store original specimens. In contrast with this, Vision systems for Mark Reader has many advantages, including function conversion to achieve other work, high accuracy, high speed, etc. In this thesis, we have researched the development of Mark Reader by using a Vision system. The processing course of this s)'stem is consist to Image Pre-Processing such as noise reduction, edge detection, threshold processing. And then, we have carried out camera calibration to calibrate images which are acquired from camera. After searching for reference point within scanning area(60pixe1${\times}$30pixe1), we have calculated points crossing by using line equations. And then, we decide to each ROI(region of interest) which are expressed by four points. Next we have converted absolute coordinate into relative coordinate for analysis a translation component. Finally we carry out Mark Reading with images classified by six patterns. As a result of experiment which follows the algorithm has proposed, we have get error within 0.5% from total image.

• Journal of the Korean Society for Precision Engineering
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• v.20 no.2
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• pp.176-183
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• 2003

The paper presents a feature recognition and segmentation method for surface approximation in reverse engineering. Efficient digitizing plays an important role in constructing a computational surface model from a physical part-surface without its CAD model on hand. Depending on its measuring source (e.g., touch probe or structured light), each digitizing method has its own strengths and weaknesses in terms of speed and accuracy. The final goal of the research focuses on an integration of two different digitizing methods: measuring by the structured light and that by the touch probe. Gathering bulk of digitized points (j.e., cloud-of-points) by use of a laser scanning system, we construct a coarse surface model directly from the cloud-of-points, followed by the segmentation process where we utilize the z-map filleting & differencing to trace out feature boundary curves. The feature boundary curves and the approximate surface model could be inputs to further digitizing by a scanning touch probe. Finally, more accurate measuring points within the boundary curves can be obtained to construct a finer surface model.

• Journal of Sensor Science and Technology
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• v.21 no.3
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• pp.217-222
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• 2012

Optical coherence tomography(OCT) is a noninvasive optical imaging tool for biomedical applications. OCT can provide depth resolved two/three dimensional morphological images on biological samples. In this paper, we integrated an OCT system that was composed of an SLED(Superluminescent Light Emitting Diode, ${\lambda}_0$=1305 nm bandwith= 141 nm), a reference arm adopting a rapid scanning optical delay line(RSOD) to get high speed imaging, and a sample arm that used a micro electro mechanical systems(MEMS) scanning mirror. The sample arm contained a compact probe for imaging dental structures. The performance of the system was evaluated by imaging in-vivo human teeth with dental calculus, and the results indicated distinct appearance of dental calculus from enamel, gum or decayed teeth. The developed probe and system could successfully confirm the presence of dental calculus with a very high spatial resolution($6{\mu}m$).

• Transactions of the Society of Information Storage Systems
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• v.3 no.2
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• pp.94-112
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• 2007

Nano-sized inverted domain dots in ferroelectric materials have potential application in ultrahigh-density rewritable data storage systems. Herein, a data storage system is presented based on scanning non-linear dielectric microscopy and a thin film of ferroelectric single-crystal lithium tantalite. Through domain engineering, we succeeded to form an smallest artificial nano-domain single dot of 5.1 nm in diameter and artificial nano-domain dot-array with a memory density of 10.1 Tbit/$inch^2$ and a bit spacing of 8.0 nm, representing the highest memory density for rewritable data storage reported to date. Sub-nanosecond (500psec) domain switching speed also has been achieved. Next, long term retention characteristic of data with inverted domain dots is investigated by conducting heat treatment test. Obtained life time of inverted dot with the radius of 50nm was 16.9 years at $80^{\circ}C$. Finally, actual information storage with low bit error and high memory density was performed. A bit error ratio of less than $1\times10^{-4}$ was achieved at an areal density of 258 Gbit/inch2. Moreover, actual information storage is demonstrated at a density of 1 Tbit/$inch^2$.

• Korean Journal of Optics and Photonics
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• v.16 no.6
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• pp.547-552
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• 2005

We have fabricated and characterized optical delay lines for optical coherence tomography, which is composed of cylindrical PZT(piezoelectric transducer) and single mode optical fiber. The polarization mode dispersion from the optical delay lines was compensated by the polarization controllers. By applying the duplex optical delay line, we minimized the thermal drift due to optical delay lines and obtained the scan range of 2 times that of a single optical delay line. The OCT system showed resolution of $18.6\pm0.5{\mu}m$, scanning range of 1.68mm, and scanning speed of 360.4mm/s.

• Journal of the Korean Society for Precision Engineering
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• v.31 no.3
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• pp.199-205
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• 2014

We propose a new variant of lateral shearing interferometer with a tunable laser source that enables 3D surface profile measurements of freeform optics with high speed, high vertical resolution, large departure, and large field-of-view. We have verified the proposed technique by comparing our measurement result with that of an existing technique and measuring a representative sample of freeform optics. Moreover, we propose a new algorithm that is able to compensate the rotational inaccuracy.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.13 no.11
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• pp.969-975
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• 2000

Laser direct writing of micro-patterned copper lines has been achieved by pyrolytic decomposition of copper formate films (Cu(HCOO)$_2$.4$H_2O$), as a metallo-organic precursor, using a focused CW Ar$^{+}$ laser beam (λ=514nm) on PCB boards and glass substrates. The linewidth and thickness of the lines wee investigated as a functin of laser power and scan speed. The profiles of the lines were measured by scanning electron microscope (SEM), surface profiler ($\alpha$-step) and atomic force measured by scanning electron microscope (SEM), surface profiler ($\alpha$-step) and atomic force microscopy (AFM). The electrical resistivities of the patterned lines were also investigated as a function of laser parameters using probe station and semiconductor analyzer. We compared resistivities of the patterned copper lines with these of the Cu bulk. Resistivities decreased due to changes in morphology and porosity of the deposit, which were about 3.8 $\mu$$\Omega$cm and 12$\mu$$\Omega$cm on PCB and glass substrates after annealing at 30$0^{\circ}C$ for 5 minutes.s.

• Journal of Welding and Joining
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• v.20 no.1
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• pp.47-54
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• 2002

Powder type Ag system insert metals were manufactured by ball milling process. The variables of milling process such as milling media, revolution speed and powder/ball weight ratio were constant except the milling time. The milling times were selected for 24, 48 and 72 hours. The insert metals made by milling process were evaluated by performing scanning electron microscope, x-ray and DSC(differential scanning calorimetry) analysis, and further in terms of wettability test. The selected insert metals that have the good characteristics compared to commercial insert metals were applied to make the brazed joints of the steel/steel and the steel/WC superhard particles. The characterizations of those brazed joints were also conducted by microstructural observations, shear tensile tests and microhardness measurements. The results indicated that milling time of 48 hours for making powder type insert metals was the best condition showing the small amount of oxides residue, low wetting angle and stable microstructure. The brazed joints that applied the 48 hours milled insert metal were very sound condition indicating the shear tensile value of $2.29{\times}102$ MPa and the microhardness of 138VHN. Further, the amount of the porosity was appeared to be lower than that of the commercial insert metals.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.6
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• pp.114-120
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• 2021

This study is focused on the root mean square and peak-to-valley based on the injection conditions of the f-theta lens, one of the main components of laser printers and laser scanning systems. The f-theta lens of an aspherical plastic lens requires ultra-preaction. Injection molding is typically used for the mass production of aspherical plastic lenses. In the injection-molding method, the resin in the lens shape is filled with the resin after melting the plastic pellets at a constant temperature and then cooled. It is necessary to maintain a uniform injection molding system to produce high-quality lenses. These injection-molding systems are influenced by different factors, such as pressure, speed, temperature, mold, and cooling. It is possible to obtain a lens that exhibits the optical characteristics required to achieve harmony. We investigated the root mean square and peak-to-valley caused by variations in temperature, a critical parameter in the melting and cooling of plastic resins generated inside and outside the injection mold.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.20 no.9
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• pp.20-27
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• 2021

The effective surface of lens was studied for injection molding process and to enable mass production of f-theta lens, which is the primary component of laser printers and laser scanning systems. Injection molding is an optimal method if f-theta lens is frequently used for the mass production of plastic lenses as an aspherical lens that requires ultra-precision. A uniform injection molding system should be maintained to produce high quality lenses. Additionally, to maintain these injection molding systems, various factors such as pressure, speed, temperature, mold and cooling should be considered. However, a lens with the optical characteristics of an f-theta lens can be obtained. The effects of melting and cooling of plastic resin on the effective surface of f-theta lenses and the numerous factors that affect the injection molding process were studied.