• Journal of the Korean Society of Combustion
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• v.8 no.1
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• pp.17-24
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• 2003

The conventional regenerative system has a high thermal efficiency as well as energy saving using the high preheated combustion air. in spite of these advantages, it can not avoid high nitric oxide emissions. Recently, flameless combustion has received much attention to solve these problems. In this research, numerical analysis is performed for flow-combustion phenomena in the self regenerative burner. In this analysis we used Fluent 6.0 code. the that is developed for commercial use, Methane gas is used as a fuel and two-step reaction model for methane and Zeldovich mechanism for NO generation are used. the velocity of the preheated combustion air is used as a parameter and we analyze the characteristics of flow-field, temperature distributions and NO emissions. Due to the increased recirculation rate, the maximum temperature of flame is significantly increased and NOx emissions is reduced.

• 한국연소학회:학술대회논문집
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• 2002.11a
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• pp.97-104
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• 2002

The conventional regenerative system has a high thermal efficiency as well as energy saving using the high preheated combustion air. in spite of these advantages, it can not avoid high nitric oxide emissions. Recently, flameless combustion has received much attention to solve these problems. In this research, numerical analysis is performed for flow-combustion phenomena in the self regenerative burner. In this analysis we used Fluent 6.0 code. the that is developed for commercial use, Methane gas is used as a fuel and two-step reaction model for methane and Zeldovich mechanism for NO generation are used. the velocity of the preheated combustion air is used as a parameter and we analyze the characteristics of flow-field, temperature distributions and NO emissions. Due to the increased recirculation rate, the maximum temperature of flame is significantly increased and NOx emissions is reduced

• Proceedings of the Materials Research Society of Korea Conference
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• 2012.05a
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• pp.64.1-64.1
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• 2012

Next generation displays such as high performance LCD, AMOLED, flexible display and transparent display require specific TFT back-planes. For high performance TFT back-planes, low temperature poly silicon (LTPS), and metal-oxide semiconductors are studied. Flexible TFT backplanes require low temperature processible organic semiconductors. Not only development of active semiconducting materials but also design and synthesis of semiconductor corresponding gate dielectric materials are important issues in those display back-planes. In this study, we investigate the high heat resistant polymeric gate dielectric materials for organic TFT and inorganic TFT with good insulating properties and processing chemical resistance. We also controlled and optimized surface energy and morphology of gate dielectric layers for direct printing process with solution processible organic and inorganic semiconductors.

• Journal of the Korean institute of surface engineering
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• v.30 no.5
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• pp.310-319
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• 1997

The purpose of this study is to investigate the effect of the specific alloying elements in steel such as Cr, Ni and Cu, and surface roughness of substrate with two different FCS temperature zones in the CAL process on the phosphatability of the cold-rolled sheet used for the drum in order to improve the zinec phosphating property. Phosphatability is dependent of the surface oxide and roughness on the substrate and can be indirectly improved by increasing surface roughness of the steel sheet. Basically, in order to obtain the good phosphatability, the low concentration of the retained elements such as Cr, Ni and Cu among the steel alloy elements should be required. Phosphatability of substrate with high concentration instead of the retained elements and surface roughness, however, can be effectively improved instead of low FSC temperature.

• Journal of Magnetics
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• v.19 no.1
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• pp.68-71
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• 2014

Copper doped Zinc Oxide nanofilms were prepared using a simple and low cost wet chemical method. The microstructures, phase structure, Raman shift and optical absorption spectrum as well as magnetization were investigated for the nanofilms. Room temperature ferromagnetism has been observed for the nanofilms. Structural analyses indicated that the films possess wurtzite structure and there are no segregated clusters of impurity phase appreciating. The results show that the ferromagnetism in Copper doped Zinc Oxide nanofilms is driven either by a carrier or defect-mediated mechanism. The present work provides an evidence for the origin of ferromagnetism on Copper doped Zinc Oxide nanofilms.

• Proceedings of the Korean Vacuum Society Conference
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• 2016.02a
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• pp.143.1-143.1
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• 2016

Ge is a promising candidate to replace Si in MOSFET because of its superior carrier mobility, particular that of the hole. However Ge oxide is thermodynamically unstable. At elevated temperature, GeO is formed at the interface of Ge and GeO2, and its formation increases the interface defect density, degrading its device performance. In search for a method to surmount the problem, we investigated Ge oxidation through an inert capped oxide layer. For this work, we prepared low doped n-type Ge(100) wafer by removing native oxide and depositing a capping layer, and show that GeO2 interface can be successfully grown through the capping layer by thermal oxidation in a furnace. The thickness and quality of thus grown GeO2 interface was examined by ellipsometry, XPS, and AFM, along with I-V and C-V measurements performed at 100K to 300K. We will present the result of our investigation, and provide the discussion on the oxide growth rate, interface state density and electrical characteristics in comparison with other studies using the direct oxidation method.

• Journal of Powder Materials
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• v.18 no.4
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• pp.347-358
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• 2011

Two different schemes were adopted to fabricate ordered macroporous structures with face centered cubic lattice of air spheres. Monodisperse polymeric latex suspension, which was synthesized by emulsifier-free emulsion polymerization, was mixed with metal oxide ceramic nanoparticles, followed by evaporation-induced self-assembly of the mixed hetero-colloidal particles. After calcination, inverse opal was generated during burning out the organic nanospheres. Inverse opals made of silica or iron oxide were fabricated according to this procedure. Other approach, which utilizes ceramic precursors instead of nanoparticles was adopted successfully to prepare ordered macroporous structure of titania with skeleton structures as well as lithium niobate inverted structures. Similarly, two different schemes were utilized to obtain disordered macroporous structures with random arrays of macropores. Disordered macroporous structure made of indium tin oxide (ITO) was obtained by fabricating colloidal glass of polystyrene microspheres with low monodispersity and subsequent infiltration of the ITO nanoparticles followed by heat treatment at high temperature for burning out the organic microspheres. Similar random structure of titania was also fabricated by mixing polystyrene building block particles with titania nanoparticles having large particle size followed by the calcinations of the samples.

• Progress in Superconductivity and Cryogenics
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• v.6 no.4
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• pp.5-8
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• 2004

A low cost MOD processing using YBCO oxide powder as a starting precursor was employed for fabrication of YBCO thin films. YBCO oxide is advantageous over metal acetates or TFA salts which are popular starting precursors for conventional MOD-TFA process. YBCO thin films were prepared by oxide-precursor-based MOD process and annealing condition was optimized. The YBCO thin film annealed at 78$0^{\circ}C$ shows no transport $I_c$ and poor microstructure. However, the YBCO thin film annealed at higher temperature shows improvement in microstructure and current transport property. In order to improve critical current, YBCO thin film was prepared by double coating method. YBCO thin film prepared with double coating approach shows enhanced superconducting performance ($I_c$>100A/cm-w).

• Korean Chemical Engineering Research
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• v.55 no.4
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• pp.483-489
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• 2017

The loss of the sulfur cathode material through dissolution of the polysulfide into electrolyte causes a significant capacity reduction of the lithium-sulfur cell during the charge-discharge reaction, thereby debilitating the electrochemical performance of the cell. We addressed this problem by using a chemical and physical approach called reduction of polysulfide dissolution through direct coating functional inorganic (graphene oxide) or organic layer (polyethylene oxide) on electrode, since the deposition of external functional layer can chemically interact with polysulfide and physically prevent the leakage of lithium polysulfide out of the electrode. Through this approach, we obtained a composite electrode for a lithium-sulfur battery (sulfur: 60%) coated with uniform and thin external functional layers where the thin external layer was coated on the electrode by solution coating and drying by a subsequent heat treatment at low temperature (${\sim}80^{\circ}C$). The external functional layer, such as inorganic or organic layer, not only alleviates the dissolution of the polysulfide electrolyte during the charging/discharging through physical layer formation, but also makes a chemical interaction between the polysulfide and the functional layer. As-formed lithium-sulfur battery exhibits stable cycling electrochemical performance during charging and discharging at a reversible capacity of 700~1187 mAh/g at 0.1 C (1 C = 1675 mA/g) for 30 cycles or more.

• 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.