• Proceedings of the KSRS Conference
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• 2007.10a
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• pp.587-590
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• 2007

The demand for more accurate and realistic 3D urban models has been increasing more and more. Many studies have been conducted to extract 3D features from remote sensing data such as satellite images, aerial photos, and airborne laser scanning data. In this paper a technique is presented to extract and reconstruct 3D buildings in urban areas using airborne laser scanning data. Firstly all points in a building were divided into some groups by height difference. From segmented laser scanning data of irregularly distributed points we generalized and regularized building boundaries which better approximate the real boundaries. Then the roof points which are subject to the same groups were classified using pre-defined models by least squares fitting. Finally all parameters of the roof surfaces were determined and 3D building models were constructed. Some buildings with complex shapes were selected to test our presented algorithms. The results showed that proposed approach has good potential for reconstructing complex buildings in detail using only airborne laser scanning data.

• Korean Journal of Remote Sensing
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• v.23 no.5
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• pp.447-453
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• 2007

The demand for more accurate and realistic 3D urban models has been increasing more and more. Many studies have been conducted to extract 3D features from remote sensing data such as satellite images, aerial photos, and airborne laser scanning data. In this paper a technique is presented to extract and reconstruct 3D buildings in urban areas using airborne laser scanning data. Firstly all points in a building were divided into some groups by height difference. From segmented laser scanning data of irregularly distributed points we generalized and regularized building boundaries which better approximate the real boundaries. Then the roof points which are subject to the same groups were classified using pre-defined models by least squares fitting. Finally all parameters of the roof surfaces were determined and 3D building models were constructed. Some buildings with complex shapes were selected to test our presented algorithms. The results showed that proposed approach has good potential for reconstructing complex buildings in detail using only airborne laser scanning data.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.10a
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• pp.165-173
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• 2005

Generally, the instrumentation scheme for urban excavation projects consist of a series of tools such as inclinometer piezometer, loadcell, tiltmeter etc. Because almost every equipments are placed along several typical lines, it is impossible to evaluate the whole behavior of structures and adjacent buildings simultaneously. With laser scanning technique developed for surveying, all visible structures are scanned in the form of 3D digital data in a time schedule as planned. It can be analysed effectively the movements for all area affected by excavation even the spots in where no instrumentation tools. Although there are some parts to be refined such as scanning error, proper analysing software, it gives many advantages for realistic instrumentation works in the near future.

• Proceedings of the Korean Institute of Communication Sciences Conference
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• 1986.10a
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• pp.194-197
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• 1986

In this paper, for the curvature correction on the scanning plane in laser scanning system, aberration correction method using holographic optical element is suggested. Holoens is selected as a type of holographic zone plate which has aberration correction property. And hologram recording condition is analyzed to find fo property. This hololens is implemented by computer-generated hologram technique. Laser scanning system is organized using desinged hololens and scanning properties of this system are investigated. Using this method optical system structure in laser scanning system can be simplified satisfying both scan linearity and field flatness.

• Korean Journal of Optics and Photonics
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• v.10 no.1
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• pp.15-20
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• 1999

Laser Scanning Unit (LSU), which is one of the core parts of laser printer, consists of LD Module, cylinder lens, polygon mirror and f$\theta$ lens. After making an initial design on each part, we optimized the one which satisfies the user specification. The optimized optical system has diffraction limited performance for the slit size of 2.7 mm$\times$1.6 mm, f$\theta$ characteristics less than 0.3% and field curvature less 1.2 mm. We also calcurate tolerance of each part based on RSS(Root Sum Square) method to manufacture LSU for mass production.

• Korean Journal of Optics and Photonics
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• v.27 no.1
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• pp.32-40
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• 2016

The characteristics of an optical system vary depending on wavelength and ambient temperature. Based on the thin-lens approximation, we investigate the conditions for stabilizing an optical system against wavelength and temperature variations at the same time. The conditions are applied to designing a laser scanning system consisting of two lenses. The change in the effective focal length of the scanning system against wavelength and temperature variations is very small, as expected.

• Proceedings of the Optical Society of Korea Conference
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• 1996.09a
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• pp.23-23
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• 1996

• Transactions of Materials Processing
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• v.18 no.7
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• pp.519-530
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• 2009

The study is concerned with shape correction of stamped product using the laser irradiation. As a fundamental study, laser irradiation process has been analyzed through the thermo-mechanical FE analysis. For the purpose of validation, laser scanning experiment has been carried out also. Since the deformation mechanism involved in the laser scanning is extremely complicated due to the highly temperature dependent material properties, the determination of laser scanning pattern is not easy for the application of real stamped parts. A simplified method for the application of springback correction has been suggested with the thermo-mechanical FE analysis.

• Journal of the Korean Society for Precision Engineering
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• v.21 no.4
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• pp.32-38
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• 2004

Laser-induced thermochemical wet etching of titanium in phosphoric acid has been investigated to examine the feasibility of this method fur fabrication of microstructures. Cutting, drilling, and milling of titanium foil were carried out while examining the influence of process parameters on etch width, etch depth, and edge straightness. Laser power, scanning speed of workpiece, and etchant concentration were chosen as major process parameters influencing on temperature distribution and reaction rate. Etch width increased almost linearly with laser power showing little dependence on scanning speed while etch depth showed wide variation with both laser power and scanning speed. A well-defined etch profile with good surface quality was obtained at high concentration condition. Fabrication of a hole, micro cantilever beam, and rectangular slot with dimension of tess than 100${\mu}{\textrm}{m}$ has been demonstrated.

• Journal of the Korean Institute of Electrical and Electronic Material Engineers
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• v.23 no.2
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• pp.133-136
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• 2010

Laser direct patterning is one of new methods which are able to replace a conventional photolithography. In order reduce the fabrication cost and to improve the luminous efficiency of AC plasma display panels (PDPs), in this experiment, a Q-switched Nd:$YVO_4$ laser was used to fabricate T-shaped indium tin oxide (ITO) display electrodes. For the laser beam scanning speed from 100 mm/sec to 800 mm/sec, T-shaped ITO patterns were clearly obtained and investigated. The experimental results showed that the optimized T-shaped ITO electrode was obtained when the lasers scanning speed was 300 mm/s.