• Proceedings of the KSME Conference
• /
• 2007.05b
• /
• pp.1997-2002
• /
• 2007

The reformer is one of the most important chemical processes for the production of high purity hydrogen from fossil fuel. This study compares zero-dimensional model with CFD models for reaction analysis of methane-steam reformer. The zero-dimensional model is an empirical equation, however CFD model uses reactions of Arrhenius type. Because the reaction coefficients of the steam-methane catalytic reforming have not been reported before in the form of Arrhenius type, the present study aims to find the appropriate reaction coefficients. The used CFD code is Fluent 6.2 version. Several models are compared for the case of various operating temperature, mass of catalyst and steam to methane ratio.

• Carbon letters
• /
• v.10 no.1
• /
• pp.5-8
• /
• 2009

We measured the non-carbon content of single-walled carbon nanotubes (SWCNTs) in SWCNT soot using thermogravimetric analysis. The weight increased percentage by the oxidation of metal in the raw soot is well obtained by TGA graph which was confirmed with ICP-AES, XRD, and XPS. This work will be very useful for the purity precise evaluation of SWCNT with UN-vis-NIR spectroscopy.

• Nuclear Engineering and Technology
• /
• v.38 no.5
• /
• pp.423-426
• /
• 2006

A developed neutron activation analysis(NAA) and gamma-spectrometry were applied to improve the analytical sensitivity and precision of impurities in electronic-circuit raw materials. It is well known that soft errors in high precision electronic circuits can be induced by alpha particles emitted from naturally occurring radioactive impurities such as U and Th. As electronic circuits have recently become smaller in dimension and higher in density, these alpha-particle emitting radioactive impurities must be strictly controlled. Therefore, new NAA methods have been established using a HTS(Hydraulic Transfer System) irradiation facility and a background reduction method. For eliminating or stabilizing fluctuated background caused by Rn-222 and its progeny nuclides in air, a nitrogen purging system is used. Using the developed NAA and gamma-spectrometry, ultra trace amounts of U(0.1ng/g) and Th(0.01ng/g) in an alumina ball and high purity silica used for an epoxy molding compound (EMC) could be determined.

• Transactions of Materials Processing
• /
• v.24 no.5
• /
• pp.323-331
• /
• 2015

Impact extrusion is an economical and productive process that can replace the multistage deep drawing process for producing deep rectangular cases. In the current work, a three-dimensional finite element analysis of the impact extrusion process of a commercial purity aluminum alloy (AA1070) was performed to predict loads, material flow, and deformed shapes using the Hansel-Spittel rheology law, which describes the flow stress at various temperatures and strain rates. The role of various process parameters such as friction, clearance between punch and die, aspect ratio and thickness of billet on the process and the shapes was analyzed.

• Tribology and Lubricants
• /
• v.26 no.2
• /
• pp.122-128
• /
• 2010

Focused Ion Beam (FIB) has been used for site-specific TEM sample preparation and small scale fabrication. Moreover, analysis on the surface microstructure and phase distribution is possible by ion channeling contrast of FIB with high resolution. This paper describes FIB applications and deformed surface structure induced by sliding. The effect of FIB process on the surface damage was explored as well. The sliding experiments were conducted using high purity aluminum and OFHC(Oxygen-Free High Conductivity) copper. The counterpart material was steel. Pin-on-disk, Rotational Barrel Gas Gun and Explosively Driven Friction Tester were used for the sliding experiments in order to investigate the velocity effect on the microstructural change. From the FIB analysis, it is revealed that ion channeling contrast of FIB has better resolution than SEM and the tribolayer is composed of nanocrystalline structures. And the thickness of tribolayer was constant regardless of sliding velocities.

• Proceedings of the KIPE Conference
• /
• 2002.07a
• /
• pp.53-57
• /
• 2002

The solar energy is purity and infinity. Solar power converter were used to convert the electrical energy from the solar arrays to a stable and reliable power source. So many countries research this solar energy system The photovoltaic system is construct many solar cell array. In this paper, new implementation solar system was showed buck converter that V-I curve produced. This system can be used to study the short-term and long-term performances of solar cell and efficiency. This system is a far more cost effective and reliable replacement for field and outdoor flight testing. Study of buck converter, analysis and control series or parallels connection characteristics of solar cell way.

• Journal of Applied Biological Chemistry
• /
• v.55 no.1
• /
• pp.61-65
• /
• 2012

Three major curcuminoids in turmeric (Curcuma longa), curcumin, demethoxycurcumin, and bisdemethoxycurcumin, were efficiently extracted by optimizing extraction condition and simultaneously analyzed and identified using reverse phase high-performance liquid chromatography, thin-layer chromatography, and liquid chromatography-mass spectrometry method. The highest yield of extraction amount 0.279 g, 9.30% was obtained by dipping method with extraction time of 7 h.

• Journal of the Korea Institute of Military Science and Technology
• /
• v.10 no.3
• /
• pp.51-61
• /
• 2007

This paper concerns about the requirement analysis for night vision imaging system(NVIS), whose purpose is to intensify the available nighttime near infrared(IR) radiation sufficiently to be caught by the human eyes on a miniature green phosphor screen. The requirements for NVIS are NVIS radiance(NR), chromaticity, daylight legibility/readability, etc. The NR is a quantitative measure of night vision goggle (NVG) compatibility of a light source as viewed through goggles. The chromaticity is the quality of a color as determined by its purity and dominant wavelength. The daylight legibility/readability is the degree at which words are readable based on appearance and a measure of an instrument's ability to display incremental changes in its output value. In this paper, the requirements of NR, chromaticity, and daylight legibility/readability for Type I and Class B/C NVIS are analyzed. Also the rationale is shown with respect to those requirements.

• 보존과학연구
• /
• s.23
• /
• pp.149-162
• /
• 2002

Gilt bronze locks(Treasure No. 1141) excavated from Hancheonsa temple are artifacts of Goryeo Dynasty. The locks underwent a conservation process from October 2001 to July 2002. The process included cleaning and the application of corrosion inhibitors, Benzotriazolesolution, as well as reinforcement treatment with Paraloid NAD-10 solution,an acrylic resin. Non-destructive XRF analysis unveil that the artifacts are made of an alloy of copper(Cu), tin(Sn) and lead(Pb), but the gilt layer is too thin to analyze the purity of the gold or the exact production method. Gilt bronze locks are important materials because they preserve all the structures of locks in Goryeo Dynasty to the smallest detail. The surface pattern is revealed through the conservation process and components of the alloy through material analysis.

• Journal of the Korean Society of Food Science and Nutrition
• /
• v.27 no.5
• /
• pp.993-999
• /
• 1998

Methanol extract of roots of Amblytropis pauciflora Kitagawa showed the antimicrobial activity to three test strains. Antimicrobial spectra of various extracts of Amblytropis pauciflora Kitagawa were tested against 24 strains of bacteria and fungi. The crude methanol extract inhibited the growth of 12 strains of bacteria and Asp. fumigatus with the exception of yeasts. The properties of the antimicrobial substance were very stable under heat(at 12$0^{\circ}C$), acid(pH 3.0) and alkali(pH 11.0) treatment. Only the root harvested in spring showed the antimicrobial activity. Among the components extracted by butanol, ginseng saponin Rg1 and various saponin-like materials were detected by TLC analysis using a plate of silica gel 60F254. The antimicrobial compound was purified by methanol extraction, activated charcoal column chromatography, Sep-pak(C18) pretreatment and reverse phase HPLC. The purified compound was detected at 13.520 min as a single peak(about 98% purity) through the HPLC analysis.