• Journal of computational fluids engineering
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• v.10 no.1
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• pp.16-23
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• 2005

The objective of this research is to estimate two dimensional ablating and charring of heat shield materials in severe aero-thermal heat transfer. This estimation requires an accurate and rapid technique for its serious heat transfer with a moving boundary. Aerodynamic heating is obtained by an explicit relation which is a function of Mach number and air condition, while a fully implicit method is used for heat transfer calculations. Moving boundary is captured by FLIAR method which is a subgroup of VOF. Thickness of ablating and charring of heat shield, temperature of the moving surface and rate of radiation heat are calculated and compared with references. The results are in good agreement with other calculations.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.23 no.9
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• pp.1201-1212
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• 1999

A numerical analysis is performed to predict the thermal response and ablation rate for charring or non-charring material which is designed to be used as thermal protection system (TPS). The numerical program composed of in-depth energy balance equation and the aerotherm chemical equilibrium (ACE) program. The ACE program calculates various thermochemical state from ablation products. The developed numerical program is verified by comparing the reported results from literature. The sensitivity tests for input parameters are performed. The thermal behavior of ablating material is mainly affected by density of ablating material, convective heat transfer coefficient and recovery enthalpy of flow field.

• 한국전산유체공학회:학술대회논문집
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• 2003.10a
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• pp.283-285
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• 2003

• 한국정보디스플레이학회:학술대회논문집
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• 2006.08a
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• pp.1154-1157
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• 2006

Organic thin-film transistors (OTFTs) based on a semiconducting polymer have been fabricated using an organic patterning methodology. Laser assisted lift-off (LALO) technique, ablating selectively the hydrophobic layer by an excimer laser, was used for producing a semiconducting polymer channel in the OTFT with high resolution. The selective wettability of a semiconducting polymer, poly (9-9-dioctylfluorene-co-bithiophene) (F8T2), dissolved in a polar solvent was found to define precisely the pattering resolution of the active channel. It is demonstrated that in the F8T2 TFTs fabricated using the LALO technique and is applicable for the larger area display.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2000.11a
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• pp.511-514
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• 2000

This work aimed to develop ITO (Indium Tin Oxide) thin films ablation with a KrF Eximer laser required for the application in flat panel display, especially patterning into small geometry on a large substrate area. The threshold fluence for ablating ITO on glass substrate is about 0.1 J/cm$^2$. And its value is much smaller than using third harmonic Nd:YAG laser. Through the optical microscope measurement the surface color of the damaged ITO is changed into dark brown and irradiated spot is completely isolated form the undamaged surroundings by laser light. The XPS analysis showed that the relative surface concentration of Sn and In were essentially unchanged (In :Sn=5:1) after irradiating Eximer laser. Using aluminium mask made by second harmonic Nd:YAG laser the ITO patterning is carried out.

• Laser Solutions
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• v.16 no.4
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• pp.17-23
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• 2013

The research for the development of roll-to-roll printing process is actively underway on behalf of the existing semiconductor process. The roll-to-roll printing system can make the electronic devices to low-cost mass production. This study is performed for developing the manufacturing technology of the printing roll used in the printing process of electronic devices. The indirect laser engraving technology is used to create printable roll and the printable roll is made out of the chrome coated roll after coating copper and polymer on the surface of steel roll, ablating the polymer on the surface of roll and etching the roll. The 3 dimensional laser scanner and roll rotating systems are constructed and the system control program is developed. We have used the fiber laser of 100 W grade, the 3 dimensional laser scanner and the 3 axes moving stage system with a rotating axis. We have found the optimal conditions by performing the laser patterning experiments and can make the minimum line width of $24{\mu}m$ by using the developed 3 dimensional laser scanner system.

• Bulletin of the Korean Chemical Society
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• v.34 no.3
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• pp.907-911
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• 2013

Numbers of matrix- and analyte-derived ions and their sum in matrix-assisted laser desorption ionization (MALDI) of a peptide were measured using 2,5-dihydroxybenzoic acid (DHB) as matrix. As for MALDI with ${\alpha}$-cyano-4-hydroxy cinnamic acid as matrix, the sum was independent of the peptide concentration in the solid sample, or was the same as that of pure DHB. This suggested that the matrix ion was the primary ion and that the peptide ion was generated by matrix-to-peptide proton transfer. Experimental ionization efficiencies of $10^{-5}-10^{-4}$ for peptides and $10^{-8}-10^{-7}$ for matrices are far smaller than $10^{-3}-10^{-1}$ for peptides and $10^{-5}-10^{-3}$ for matrices speculated by Hillenkamp and Karas. Number of gas-phase ions generated by MALDI was unaffected by laser wavelength or pulse energy. This suggests that the main role of photo-absorption in MALDI is not in generating ions via a multi-photon process but in ablating materials in a solid sample to the gas phase.

• Transactions on Electrical and Electronic Materials
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• v.1 no.4
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• pp.20-24
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• 2000

This study aimed to develop ITO(Indium Tim Oxide) tin films ablation with a pulsed type KrF excimer laser required for the electrode patterning application in flat panel display into small geometry on a large substrate are. The threshold fluence for ablating ITO on glass substrate is about 0.1 J/㎠. And its value is much smaller than that using 3 .sup rd/ harmonic Nd:YAG laser. Through the optical microscope measurement the surface color of the ablated ITO is changed into dark brown due to increase of surface roughness and transformation of chemical composition by the laser light. The laser-irradiated regions were all found to be electrically isolating from the original surroundings. The XPS analysis showed that the relative surface concentration of Sn and In was essentially unchanged (In:Sn=5:1)after irradiating the KrF excimer laser. Using Al foil made by 2$\^$nd/ harmonic Na:YAG laser, the various ITO patterning is carried out.

• Journal of Chest Surgery
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• v.50 no.3
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• pp.171-176
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• 2017

Background: In elderly patients who have atrial fibrillation (AF), surgical ablation of the arrhythmia during cardiac surgery may be challenging. Despite the reported advantages of ablating AF with the Cox maze procedure (CMP), the addition of the CMP may complicate other cardiac operations. We evaluated the effect of the CMP in elderly patients concurrent with other cardiac operations. Methods: From October 2007 to December 2015, we enrolled 27 patients aged >70 years who had AF and who underwent the CMP concurrently with other cardiac operations. The mean preoperative additive European System for Cardiac Operative Risk Evaluation score was $8{\pm}11$ (high risk). Results: Only 1 hospital death occurred (4%). The Kaplan-Meier method showed a high 5-year cumulative survival rate (92%). At mean follow‐up of 51 months, 23 patients (89%) had sinus rhythm conversion. The postoperative left atrial dimensions did not significantly differ between the 8 patients who had reduction plasty for giant left atrium ($53.4{\pm}7.5cm$) and the 19 patients who did not have reduction plasty ($48.7{\pm}5.7cm$). Conclusion: In patients aged >70 years, concurrent CMP may be associated with a high rate of sinus rhythm conversion without increased surgical risk, despite the added complexity of the main cardiac procedure.

• Analytical Science and Technology
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• v.15 no.1
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• pp.7-14
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• 2002

Laser ablation ion trap mass spectrometry (LAITMS) was developed for the analysis of metal and ceramic samples. For this study, XeCl excimer laser (308 nm) was used for ablating the samples and ITMS was used as a detector. Samples were introduced from outside of a ring electrode and this way of sample introduction was very effective for solid samples when laser ablation was employed. Helium gas was used as a buffer gas, and its effect on sensitivity and some parameters (buffer gas pressure, ion storage time, and cut-off RF voltage) were studied. The optimized conditions were $1{\times}10^{-4}$ Torr of buffer gas pressure, 100 ms of ion storage time and $1150V_{p-p}$ of cut-off RF voltage. From that results, copper (Cu) and molybdenum (Mo) metals were tested with LAITMS and the mass spectra of these pure metals were compared with the natural abundance of isotope ratio. We also examined ceramic samples ($Al_2O_3$, $ZrO_2$) and represented the result of elemental analysis.