• 한국태양에너지학회:학술대회논문집
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• 2011.04a
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• pp.92-97
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• 2011

Nowdays the most critical problem is global warming and the most important reason is the high emition of carbondioxide. 23% of the use of carbondioxide is used in building and decreasing the use of it is very important. One of the biggest factor that can decrease the use of energy is developing the heat conducting ratio of the materials we use in building. Heat conducting ratio is the important factor in the use of reducing energy comsumation. In this research, there are methods about how to measure the heat conducting ratio, and the existing the representing measuring method which is Heat Flow Meter HFM 436, Laser Flash Analysis and find out about the TCi of the new method C-Therm and compare the results.

• Proceedings of the International Microelectronics And Packaging Society Conference
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• 2002.11a
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• pp.153-157
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• 2002

Thermal management is very important for the success of high density circuit design in LTCC. To realized more accurate thermal analysis for structure design, a series of simple thermal resistance measurement by laser flash method and parametric numerical analysis have been carried out. The design of via filled material would be useful in thermal management of power devices.

• Journal of the Microelectronics and Packaging Society
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• v.10 no.1
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• pp.39-43
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• 2003

Thermal management is very important for the success of high density circuit design in LTCC. In this paper, LTCC substrates containing thermal via and pad were fabricated in order to study the influence of the thermal dissipation. To realize the accurate thermal analysis for structure design, a series of simple thermal conductivity measurement by laser flash method and parametric numerical analysis have been carried out. The LTCC substrate including via and Ag pad has good thermal conductivity over 103 W/mK which is 44% value of pure Ag material. Thermal behaviors with via arrays, size and density in the LTCC substrate were studied by numerical method.

• Journal of the Korea Institute of Information Security & Cryptology
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• v.24 no.3
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• pp.453-460
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• 2014

Fault injection attack is the process of attempting to acquire the information on-chip through inject artificially generated error code into the cryptographic algorithms operation (or perform) which is implemented in hardware or software. From the details above, the laser-assisted failure injection attacks have been proven particularly successful. In this paper, we propose an improved laser probing system for fault injection attack which is called the Dual-Laser FA tool set, a hybrid approach of the Flash-pumping laser and fiber laser. The main concept of the idea is to improve the laser probe through utilizing existing equipment. The proposed laser probe can be divided into two parts, which are Laser-I for laser cutting, and Laser-II for fault injection. We study the advantages of existing equipment, and consider the significant parameters such as energy, repetition rate, wavelength, etc. In this approach, it solves the high energy problem caused by flash-pumping laser in higher repetition frequency from the fiber laser.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.5 s.248
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• pp.413-421
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• 2006

The bubble dynamics induced by direct laser heating is experimentally analyzed as a first step to assess the technical feasibility of laser-based ink-jet technology. To understand the interaction between laser light and ink, the absorption spectrum is measured for various ink colors and concentrations. The hydrodynamics of laser-generated bubbles is examined by the laser-flash photography. When an Ar ion laser pulse (wavelength 488 nm) with an output power up to 600 mW is incident on the ink solution through a transparent window, a hemispherical bubble with a diameter up to ${\sim}100{\mu}m$ can be formed with a lifetime in a few tens of microsecond depending on the laser power and the focal-spot size. Parametric study has been performed to reveal the effect of laser pulse width, output power, ink concentration, and color on the bubble dynamics. The results show that the bubble generated by a laser pulse is largely similar to that produced by a thin-film heater. Consequently, the present work demonstrates the feasibility of developing a laser-actuated droplet generation mechanism for applications in ink-jet print heads. Furthermore, the results of this work indicate that the droplet generation frequency is likely to be further increased by optimizing the process parameters.

• Korean Journal of Materials Research
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• v.31 no.12
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• pp.665-671
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• 2021

A 1.8 ㎛ thick polycrystalline diamond (PCD) thin film layer is prepared on a Si(100) substrate using hot-filament chemical vapor deposition. Thereafter, its thermal conductivity is measured using the conventional laser flash analysis (LFA) method, a LaserPIT-M2 instrument, and the newly proposed light source thermal analysis (LSTA) method. The LSTA method measures the thermal conductivity of the prepared PCD thin film layer using an ultraviolet (UV) lamp with a wavelength of 395 nm as the heat source and a thermocouple installed at a specific distance. In addition, the microstructure and quality of the prepared PCD thin films are evaluated using an optical microscope, a field emission scanning electron microscope, and a micro-Raman spectroscope. The LFA, LaserPIT-M2, and LSTA determine the thermal conductivities of the PCD thin films, which are 1.7, 1430, and 213.43 W/(m·K), respectively, indicating that the LFA method and LaserPIT-M2 are prone to errors. Considering the grain size of PCD, we conclude that the LSTA method is the most reliable one for determining the thermal conductivity of the fabricated PCD thin film layers. Therefore, the proposed LSTA method presents significant potential for the accurate and reliable measurement of the thermal conductivity of PCD thin films.

• Laser Solutions
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• v.7 no.1
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• pp.29-36
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• 2004

The dynamics of laser-induced plasma/shock wave and the interaction with a surface in the laser shock cleaning process are analyzed by optical diagnostics. Shock wave is generated by a Q-switched Nd:YAG laser in air or with N$_2$, Ar, and He injection into the focal spot. The shock speed is measured by monitoring the photoacoustic probe-beam deflection signal under different conditions. In addition, nanosecond time-resolved images of shock wave propagation and interaction with the substrate are obtained by the laser-flash shadowgraphy. The results reveal the effect of various operation parameters of the laser shock cleaning process on shock wave intensity, energy-conversion efficiency, and flow characteristics. Discussions are made on the cleaning mechanisms based on the experimental observations.

• Korean Journal of Optics and Photonics
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• v.31 no.2
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• pp.59-70
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• 2020

We discuss a modified numerical model based on the Monte Carlo radiative transfer (MCRT) method, i.e., the MCRT matrix method, for the analysis of atmospheric scattering effects in three-dimensional flash LIDAR systems. Based on the MCRT method, the radiative transfer function for a LIDAR signal is constructed in a form of a matrix, which corresponds to the characteristic response. Exploiting the superposition and convolution of the characteristic response matrices under the paraxial approximation, an extended computer simulation model of an overall flash LIDAR system is developed. The MCRT matrix method substantially reduces the number of tracking signals, which may grow excessively in the case of conventional Monte Carlo methods. Consequently, it can readily yield fast acquisition of the signal response under various scattering conditions and LIDAR-system configurations. Using the computational model based on the MCRT matrix method, we carry out numerical simulations of a three-dimensional flash LIDAR system operating under different atmospheric conditions, varying the scattering coefficient in terms of visible distance. We numerically analyze various phenomena caused by scattering effects in this system, such as degradation of the signal-to-noise ratio, glitches, and spatiotemporal spread and time delay of the LIDAR signals. The MCRT matrix method is expected to be very effective in analyzing a variety of LIDAR systems, including flash LIDAR systems for autonomous driving.

• Bulletin of the Korean Chemical Society
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• v.20 no.12
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• pp.1441-1446
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• 1999

Laser-induced fluorescence (LIF) spectroscopy has been applied to study the supersonic jet of radicals of nitric oxide (NO) and atomic iodine produced in the flash pyrolysis of precursors n-butylnitrite (CH₃(CH₂)₃ONO) and allyl iodide (C₃$H_5$I), respectively. The systematic population analysis with spectral simulations demonstrates that the precursors are efficiently pyrolyzed and that radical beams show a substantial supersonic cooling. In addition, absence of local equilibrium was observed in the distributions of two electronic spin-orbit states ²Π$_{1/2}$ and ²Π$_{3/2}$ of NO products and can be rationalized in terms of the efficiency of collision-induced energy transfer rates.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2018.05a
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• pp.21-22
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• 2018