• Proceedings of the Korean Society of Precision Engineering Conference
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• 1997.10a
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• pp.887-890
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• 1997

Recently micromachining using DPSSL(Diode Pumped Solid State Laser) with 3rd harmonic wavelength is actively studied in laser machining area. Micromachining using DPSSL have outstanding advantages as UV source comparing with excimer laser in various aspect such a maintenance cost, maskless machining, high repetition rate and so on. In this study micro-drilling of PCB type substrate which consists of Cu-PI-Cu layer was performed using DPSS Nd:YAG laser(355nm, wavelength) in vector scanning method. Experimental and numerical method(Matlab simulation, FEM) are used to optimize process parameter and control machining depth. The man mechanism of this process is laser ablation. It is known that there is large gap between energy threshold of copper and that of PI. Matlab simulation considering energy threshold of material is performed to effect of duplication of pulse and FEM thermal analysis is used to predict the ablation depth of copper. This study could be widely used in various laser micromachining including via hole microdrilling of PCB, and micromachining of semiconductor components, medical parts and printer nozzle and so on.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.5
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• pp.434-441
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• 2018

The pore size of nickel (Ni) bottom electrode layer (BEL) for low-temperature solid oxide fuel cells embedded with ultrathin-film electrolyte was controlled by changing the substrate surface morphology and deposition process parameters. For ~150-nm-thick Ni BEL, the upper side of an anodic aluminum oxide (AAO) substrate with ~65-nm-sized pores provided ~1.7 times smaller pore size than the lower side of the AAO substrate. For ~100-nm-thick Ni BEL, the AAO substrate with ~45-nm-sized pores provided ~2.6 times smaller pore size than the AAO substrate with ~95-nm-sized pores, and the deposition pressure of ~4 mTorr provided ~1.3 times smaller pore size than that of ~48 mTorr. On the AAO substrate with ~65-nm-sized pores, the Ni BEL deposited for 400 seconds had ~2 times smaller pore size than the Ni BEL deposited for 100 seconds.

• Journal of the Korean Wood Science and Technology
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• v.33 no.5 s.133
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• pp.92-98
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• 2005

This study was performed to get the basic information concerned to the optimum culture condition of Inonotus obliquus. Several solid media, PDA, MEA and Czapek-Dox, and three liquid media were adopted for the in vitro cultivation. Some main features of the fungal morphological characteristics under cultivation conditions were observed and described. Preliminary results showed that appearance of the mycelial mat, hyphal size and substrate pigmentation differed according to the media. The PDA medium was the most favorable substrate for the growth on solid culture, followed by MEA and Czapek-Dox media. Concerned to the addition of amino acids, 5 amino acids, such as alanine, alginine, isoleucine, leucine and threonine, enhanced to the mycelial growth. Isoleucine was shown the best fungal growth. An important morphological hyphal structure for the fungus, the setae, was found in abundance and diverse its shape and size. In liquid culture, fresh potato broth was the best growth stimulant of the fungus, followed by Malt extract and potato broth. Addition of yeast extract to the liquid media had improved the biomass, but not laccase production.

• Journal of Microbiology and Biotechnology
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• v.20 no.3
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• pp.525-531
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• 2010

This work was aimed at utilizing rice bran as a substrate for $\beta$-carotene production by Rhodotorula glutinis DM 28 under optimized conditions of solid-state fermentation. The biomass and $\beta$-carotene content of Rhodotorula glutinis DM 28 grown on rice bran as a sole substrate under solid-state fermentation were 54 g/kg rice bran and 1.65 mg/kg rice bran, respectively. Its biomass and $\beta$-carotene content, however, could be improved by 60% and 30%, respectively, using the Central Composite Design for the optimization of its cultivation conditions. The optimized conditions obtained were a pH of 5, a moisture content of 70% (w/w), and a carbon-to-nitrogen ratio of 4. Under these conditions, rice bran containing R. glutinis DM 28 had nutritional values of $\beta$-carotene, protein, and fat higher than those of rice bran alone. Yeast-grown rice bran could be suitable, therefore, to use as a $\beta$-carotene-enriched supplement in animal feeds.

• Proceedings of the Korean Society for Applied Microbiology Conference
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• 2005.06a
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• pp.204-211
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• 2005

The technology of Solid-State-Fermentation (SSF) with corn straw by Pichia ohmeri T021 was studied in this article. After being crushed, the corn straw powder was added into vitriol solutions to hydrolysis, which the quality proportion of corn straw: water: vitriol (98%) is 20:80:1. The mixtures was incubated at 120$^{\circ}C$ for 1 hour, and the hydrolysis rate reached 19%. Following, the mixture was adjusted to pH 4.5 by sodium carbonate and added cellulase (25IFPU/g). The hydrolysis rate reached 15% after the mixture was incubated at 50$^{\circ}C$ for 25h. The mixture which hydrolysed by vitriol was inoculated by Pichia ohmeri T021 (5${\times}10^7$cell/g) and added cellulase (25 IFPU/g) at the same time. The ethanol yield reached 2.99g per 100 gram substrate after the fermenting grains was incubated at 33$^{\circ}C$, pH 4.5 for 5 days.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2006.05a
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• pp.41-45
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• 2006

The study on laser-ablation plasmas has been strongly interested in fundamental aspects of laser-solid interaction and consequent plasma generation. In particular, this plasma has been widely used for the deposition of thin solid films and applied to the semiconductors and insulators. In this paper, we developed and discussed the generation of carbon ablation plasmas emitted by laser radiation on a solid target, graphite. The progress of carbon plasmas by laser-ablation was simulated using Monte-Carlo particle model under the pressures of vacuum, 1 Pa, 10 Pa and 66 Pa. At the results, carbon particles with low energy were deposited on the substrate as the pressure becomes higher. However, there was no difference of deposition distributions of carbon particles on the substrate regardless of the pressure.

• Corrosion Science and Technology
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• v.20 no.6
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• pp.384-390
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• 2021

In this paper, durability evaluation and surface damage mechanism were investigated through solid particle erosion (SPE) test after applying hot-dip aluminizing (HDA) technology for the purpose of maintenance of marine economizer tube. Damaged surface shape was analyzed using SEM and 3D microscope. Compositional changes and microstructure of the HDA layer were analyzed through EDS and XRD. Durability was evaluated by analyzing weight loss and surface damage depth after SPE. HDA was confirmed to have a two-layer structure of Al and Al₅Fe₂. HDA+HT was made into a single alloy layer of Al₅Fe₂ by diffusion treatment. In the microstructure of HDA+HT, void and crack defect were induced during the crystal phase transformation process. The SPE damage mechanism depends on material properties. Plastic deformation occurred in the substrate and HDA due to ductility, whereas weight loss due to brittleness occurred significantly in HDA+HT. As a result, the substrate and HDA showed better SPE resistance than HDA+HT.

• Bulletin of the Korean Chemical Society
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• v.34 no.2
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• pp.353-354
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• 2013

• Journal of the Korean Ceramic Society
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• v.39 no.1
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• pp.86-91
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• 2002

Solid Oxide Fuel Cells (SOFC) are of great interest of next generation energy conversion system due to their high energy efficiency and environmental friendliness. The basic SOFC unit consists of anode, cathode and solid electrolyte. Among these components, anode plays the most important role for the oxidation of fuel to generate electricity and also behaves as a substrate of the whole cell. It is normally requested that the anode materials should have the high electrical conductivity and gas permeability to reduce the polarization loss of the cell. In this study, the effect of pore former on the microstructure of anode substrate was investigated and thus on the electrical conductivity and the gas permeability. According to the results, microstructure and electrical conductivity of anode substrate were greatly influenced by the shape of pore former and especially by the anisotrpy of the pore former. The use of anisotropic pore former is supposed to deteriorate the cell performance by which the electrical conduction path is disconnected but also the effective gas diffusion path for the fuel is reduced.

• The Korean Journal of Ceramics
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• v.5 no.4
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• pp.336-340
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• 1999

Glasses in the system $CaO-TiO_2-SiO_2-Al_2O_3-ZrO_2-B_2O_3$ were investigated to find the glass seal compositions suitable for use in the planar solid oxide fuel cell (SOFC). Glass-ceramics prepared from the glasses by one-stage heat treatment at $1,000^{\circ}C$ showed various thermal expansion coefficients (i,e., $8.6\times10^{-6^{\circ}}C^{-1}$ to $42.7\times10^{-6^{\circ}}C^{-1}$ in the range 25-$1,000^{\circ}C$) due to the viscoelastic response of glass phase. The average values of contact angles between the zirconia substrate and the glass particles heated at 1,000-$1,200^{\circ}C$ were in the range of $131^{\circ}\pm4^{\circ}$~$137^{\circ}\pm9^{\circ}$, indicating that the glass-ceramic was in partial non-wetting condition with the zirconia substrate. With increasing heat treatment time of glass samples from 0.5 to 24 h at $1,100^{\circ}C$, the DC electrical conductivity of the resultant glass-ceramics decreased from at $800^{\circ}C$. Isothermal hold of the glass sample at $1100^{\circ}C$ for 48h resulted in diffusion of Ca, Si, and Al ions from glass phase into the zirconia substrate through the glass/zirconia bonding interface. Glass phase and diffusion of the moving ion such as $Ca^{2+}$ in glass phase is responsible for the electrical conduction in the glass-ceramics.