• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2001.11b
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• pp.484-487
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• 2001

Amorphous carbon thin films were deposited using laser ablation technique on Si(100) substrates at different temperatures. In this study, effects of the substrate temperature on the properties of amorphous carbor, films were systematically investigated. The surface morphologic and structural properties of the films were studied by scanning electron microscopy (SEM) and raman spectroscope, respectively. With increasing of the substrate temperature, the surface morphologies were changed significantly. Moreover the intensity ratio of D-band and G-band and the full width at half maximum of these bands were dependent on substrate temperatures.

• Proceedings of the KIEE Conference
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• 1999.11d
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• pp.888-890
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• 1999

ZnO thin films on (001) sapphire substrates have been deposited by pulsed laser deposition using a Nd:YAG laser with the wavelength of 355 nm at an oxygen pressure of 350 mTorr. In order to investigate the effect of the substrate temperature on the properties of ZnO thin films, the experiment has been performed at various substrate temperatures in the range of $200^{\circ}C$ to $700^{\circ}C$. According to XRD, (002) textured ZnO films of high crystalline quality have been obtained by pulsed laser deposition technique. However, the intensity of UV emission is mostly depending on the stoichiometry of ZnO films.

• Journal of the Korean Applied Science and Technology
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• v.12 no.2
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• pp.151-156
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• 1995

The influences of fluorophor, scatterer, absorber in turbid material by light scattering were interpreted for the scattered fluorescence intensity and wavelength, it has been studied the molecular properties by laser induced fluorescence spectroscopy. It has been found that the effects of optical properties in scattering media by the optical parameters(${\mu}_{s}$, ${\mu}_{a}$, ${\mu}_{t}$). The value of scattering coefficient ${\mu}_{s}$ is large by means of the increasing particles of scatterer, it has been found that the slope decays exponentially as a function of distance from laser source to detector. It may also aid in designing the best model for oil chemistry, laser medicine and application of medical engineering.

• Korean Journal of Optics and Photonics
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• v.4 no.3
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• pp.330-337
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• 1993

Figure '8' type, passively-mode-locked erbium-doped-fiber ring laser was developed, incorporating a nonlinear loop mirror. Transmittance of the loop mirror was found to be dependent on the incident light intensity due to the non-reciprocal nonlinear phase shift, which enables the passive mode locking of the laser. Self-starting of stable mode locking was possible with only controlling the polarization controllers inside the cavity without any help of external perturbation or modulation. The mode-locked output pulse shape was discussed in relation with the transmission characteristics of nonlinear loop mirror.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
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• 2005.04a
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• pp.117-121
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• 2005

In order to monitor the levels and seasonal variations of EDCs, samples of the discharged effluent from sewage & wastewater treatment plants and river waters were collected. The target EDCs including bisphenol A and alkylphenols were determined by Laser-induced fluorescence(LIF) as in-situ monitoring technique. The category of EDCs showed similar fluorescence spectra and nearly equal decay time. This point makes it hard to distinguish each EBCs from the EDCs mixture by LIF and LIF results were expressed only by the total EDCs. However, LIF monitoring results and GC-MS results was comparable. The correlation coefficient between EDCs concentration acquired from GC-MS and fluorescence intensity from LIF was significant. This study supports the feasibility of the application of LIF into EDCs monitoring In aquatic system.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.181-182
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• 2011

Phase-change materials can be cycled by exposure to laser beam, and as a function of the pulse intensity and duration, the laser beam triggers the switching from crystalline to amorphous phase and back. In other to progress better crystallization transition and amorphization long phase-transformation data of phase-change memory (PRAM), we investigated about the effect of Sb doping and Ag ions percolating into Ge-Se-Te phase-change material. Doped Sb concentrations was determined each of 10, 20 and 30 wt%. As the Sb-doping concentration was increased, the resistivity decreased and the crystallization temperature increased. Ionization of Ag was progressed by DPSS laser (532 nm) for 1 hour. The resistivity was more decreased and the crystallization temperature was more increased in case of adding Ag layer under Sb-(Ge-Se-Te) thin film. At the every condition of thin films included Ag layer more stable states were indicated compare with just Sb-doped Ge-Se-Te thin films.

• Analytical Science and Technology
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• v.8 no.4
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• pp.779-786
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• 1995

Environmental and industrial aerosols can be analyzed on-line by laser plasma spectroscopy. The main problem in direct (no preparation or presorting) aerosol analysis is the extensive spectral fluctuations. A method to partially solve this problem is proposed. It is based on single shot measurements and application of a special rejection algorithm. The major factors that influence the spectral variations are discussed, in relation to the correction possibility by a rejection program. The method works well when average intensity of the single spectra is relatively high, as compared to detector's saturation limit. If intensities are too low, the accumulation of readout noise is critical, and no improvement is expected.

• Electrical & Electronic Materials
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• v.11 no.11
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• pp.28-36
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• 1998

Widely tunable diodes integrated with periodically sampled and chirped DBR(distributed Bragg reflector) and an EA(electroabsorption) modulator are analyzed dynamically using the improved largesinal time-domain model. The tuning characteristics of sampled- and chirped-grating DBR laser diodes are demonstrated theoretically. The results of the simulation agree well with those of the experiment. And the intensity-modulation properties of the laser diodes integrated with an EA modulator are calculated. It is shown that the external modulation has the lower frequency chirp by 1/20 for the same extinction ratio than the direct modulation, and also the short pulse train can be generated using the optical gating of an EA modulator.

• Journal of ILASS-Korea
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• v.10 no.3
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• pp.17-28
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• 2005

The Holographic Particle Velocimetry system can be a promising optical tool for the measurements of three dimensional particle velocities. In this study, diffused illumination holographic system to measure the sizes and 3D velocities of moving particles based on automatic image processing was developed. First of all basic optical systems for pulse laser recording, continuous laser reconstruction, and image acquisition, were constructed. To determine the position of particles in the optical axis, new three auto-focusing parameters(AEP), namely, Correlation Coefficient, Sharpness Index, and Depth Intensity were introduced and verified. The developed system was applied to spray droplets to validate the capability of the system. Three dimensional positions of particles viewed from two sides were decided using AFP and then 3D velocities of Particles were extracted by particle tracking algorithm. Comparison of measurement results of sizes and 3D velocities of particles with those obtained by laser instrument, PDPA, showed good consistency of the developed holographic system.

• Journal of Institute of Control, Robotics and Systems
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• v.16 no.7
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• pp.617-624
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• 2010

This article describes the system architecture of KUVE (KIST Unmanned Vehicle Electric) and unmanned autonomous navigation of it in KIST. KUVE, which is an electric light-duty vehicle, is equipped with two laser range finders, a vision camera, a differential GPS system, an inertial measurement unit, odometers, and control computers for autonomous navigation. KUVE estimates and tracks the boundary of road such as curb and line using a laser range finder and a vision camera. It follows predetermined trajectory if there is no detectable boundary of road using the DGPS, IMU, and odometers. KUVE has over 80% of success rate of autonomous navigation in KIST.