• Journal of the Korean Professional Engineers Association
• /
• v.33 no.1
• /
• pp.75-82
• /
• 2000

299 chemical analyses are used to study the characteristics of mineral and thermal waters in South Korea. Even though the concentration of chemical components in thermal waters are generally very low, mineral waters having components more than 1,000 ppm of dissolved total solid(TDS) are reached up to 1975 of total analyses data, In Germany, Japan or some other countries, mineral and thermal waters are defined not only by water temperature, but also by chemical components. The principle of Law in Japan is also almost same with the German regulations. However, the Law for thermal spring In Korea permit thermal water to be qualifiled only by water temperature. For including chemical characters into the regulations or Law of thermal spring, the limit values of TDS and other 9 micro components related to mineral and thermal waters was selected through this study.

• Nuclear Engineering and Technology
• /
• v.29 no.1
• /
• pp.58-67
• /
• 1997

A numerical study has been peformed to investigate the flow and mixing characteristics of a chemical injection tank in the chemical and volume control system (CVCS) of Yonggwang 5&6 (YGN 5&6). This study was undertaken to provide a basis for modification of the previous design (YGN 3&4) which gave a lot of difficulties in installation and operation of the chemical injection system during the start-up test because it needs a special reciprocating pump with a high actual head. For the tank of length-to-diameter ratios (L/D) of 1,2 and 3, each with and without a baffle inside, calculation results were obtained by solving the unsteady laminar two-dimensional elliptic forms of governing equations for the mass, momentum and species concentration. Finite-difference method was used to obtain discretized equations, and the SIMPLER solution algorithm, which was developed based on the staggered grid control volume, was employed for the calculation procedure. Results showed that the baffle is very effective in enhancing the mixing in the tank and that a baffle should be installed near the tank entrance in order to 110 chemicals into the reactor coolant system (RCS) within the operating time required.

• Journal of the Korean institute of surface engineering
• /
• v.26 no.6
• /
• pp.334-340
• /
• 1993

The physico-chemical properties and characteristics after thermal treatment of natural zeolite from Kampo area were studied. The physico-chemical properties of natural zeolite were studied by investigating chemical composition, x-ray diffraction pattern(XRD), scanning electronic microscope(SEM), infrared spec-tra(IR), thermal analysis(TA), and cation exchange capacity(C.E.C.), and the characteristics of natural zeo-lite after thermal treatment from $400^{\circ}C$ to $900^{\circ}C$ were compared with the natural zeolite. This study showed that clinoptilolite was the predominant costituent in natural zeolite, and the natural zeolite contained a little amount of quartz and feldspar as impurities. Zeolite mineral was seen to develop slowly by the natural alternation of volcanic ash considering the almost amorphous crystal structure. The more temperature of ther-mal treatment increased, the more adsorption capacity decreased, considering the fact that the hydroxy peak diminished on infrared spectra, and that cation exchange capacity also decreased distinctly.

• Journal of The Geomorphological Association of Korea
• /
• v.23 no.2
• /
• pp.71-81
• /
• 2016

According to the result obtained by the CIA analysis(A-CN-K and A-CNK-FM ternary diagram), the chemical weathering of granitic grus in Chuncheon basin is too weak, thus calcium and sodium may not be dissolved sufficiently, but go as far as to be more progress than that of Yeongju-Bonghwa basin, Jeongeup, Nonsan and Namwon, common granitic grus in Korean Peninsula. Therefore the chemical characteristics of granitic hills in Chuncheon basin show that granitic weathered mantles are not saprolite formed by alteration while this may be true for guns(sandy weathered mantles). The weathered mantles of inner hills in the basin is slightly altered, footslope of mountains are more altered, and footslope hills are undergone some alteration. But their alteration doesn't show any advances to saprolite, and most of them are still in incipient weathering stage.

• Korean Journal of Plant Resources
• /
• v.21 no.3
• /
• pp.222-225
• /
• 2008

Chemical composition and enzymatic saccharification characteristics of hemp woody core were investigated by their chemical composition analysis and enzymatic saccharification with commercially available cellulases (Celluclast 1.5L and Novozym 342). Hemp woody core have higher xylan and lower lignin contents than its bast fiber. Based on hemicelluloses and lignin composition, hemp woody core is similar with hardwood biomass. However, cellulose was more easily converted to glucose than xylan to xylose and this trend was confirmed both hemp woody core and yellow poplar. Hemp woody core biomass shows higher saccharification than yellow poplar (hardwood biomass) based on cellulose and xylan hydrolysis. With easier enzymatic saccharification in cellulose and xylan, and similar chemical composition, hemp woody core have better biorefinery feedstock characteristics than hardwood biomass.

• Corrosion Science and Technology
• /
• v.8 no.1
• /
• pp.15-20
• /
• 2009

Surface of PEEK(poly-ether-ether-ketone) was modified by chemical etching, plasma treatment and mechanical grinding to improve the plating adhesion. The plating characteristics of these samples were studied by the contact angle, plating thickness, gloss and adhesion. Chemical etching and plasma treatment increased wettability, adhesion and gloss. The contact angle of as-received PEEK was $61^{\circ}$. The contact angles of chemical etched, plasma treated or both were improved to the range of $15{\sim}33^{\circ}$. In the case of electroless plating, the thickest layer without blister was $1.6{\mu}m$. The adhesion strengths by chemical etching, plasma treatment or both chemical etching and plasma treatment were $75kgf/cm^2$, $102kgf/cm^2$, $113kgf/cm^2$, respectively, comparing to the $24kgf/cm^2$ of as-received. In the case of mechanically ground PEEKs, the adhesion strengths were higher than those unground, with the sacrifice of surface gloss. The gloss of untreated PEEK were greater than mechanically ground PEEKs. Plating thickness increased linearly with the plating times.

• Bulletin of the Korean Chemical Society
• /
• v.35 no.6
• /
• pp.1687-1691
• /
• 2014

This study reports on the synthesis of carbon nanofibers via chemical vapor deposition using Co and Cu as catalysts. In order to investigate the suitability of their catalytic activity for the growth of nanofibers, we prepared catalysts for the synthesis of carbon nanofibers with Cobalt nitrate and Copper nitrate, and found the optimum concentration of each respective catalyst. Then we made them react with Aluminum nitrate and Ammonium Molybdate to form precipitates. The precipitates were dried at a temperature of $110^{\circ}C$ in order to be prepared into catalyst powder. The catalyst was sparsely and thinly spread on a quartz tube boat to grow carbon nanofibers via thermal chemical vapor deposition. The characteristics of the synthesized carbon nanofibers were analyzed through SEM, EDS, XRD, Raman, XPS, and TG/DTA, and the specific surface area was measured via BET. Consequently, the characteristics of the synthesized carbon nanofibers were greatly influenced by the concentration ratio of metal catalysts. In particular, uniform carbon nanofibers of 27 nm in diameter grew when the concentration ratio of Co and Cu was 6:4 at $700^{\circ}C$ of calcination temperature; carbon nanofibers synthesized under such conditions showed the best crystallizability, compared to carbon nanofibers synthesized with metal catalysts under different concentration ratios, and revealed 1.26 high amorphicity as well as $292m^2g^{-1}$ high specific surface area.

• Korean Chemical Engineering Research
• /
• v.53 no.3
• /
• pp.315-320
• /
• 2015

Characteristics of gas-liquid mass transfer and interfacial area were investigated in a bubble column of diameter and height of 0.102 m and 2.5 m, respectively. Effects of gas and liquid velocities on the volumetric gas-liquid mass transfer coefficient ($k_La$), interfacial area (a) and liquid side true mass transfer coefficient ($k_L$) were examined. The interfacial area and volumetric gas-liquid mass transfer coefficient were determined directly by adopting the simultaneous physical desorption of $O_2$ and chemical absorption of $CO_2$ in the column. The values of $k_La$ and a increased with increasing gas velocity but decreased with increasing liquid velocity in the bubble column which was operated in the churn turbulent flow regime. The value of $k_L$ increased with increasing gas velocity but did not change considerably with increasing liquid velocity. The liquid side mass transfer was found to be related closely to the liquid circulation as well as the effective contacting frequency between the bubbles and liquid phases.

• Korean Chemical Engineering Research
• /
• v.48 no.2
• /
• pp.212-217
• /
• 2010

In this study, suspension polymerized toners were prepared by using poly(vinyl alcohol)(PVA) as an organic suspending agent. Styrene and butylacrylate monomers were used simultaneously with carbon black to prepare microspherical polymerized toners with a narrow-particle size distribution. Preliminary particles without carbon black were polymerized first to optimize suspension polymerization conditions. The preliminary particles were prepared at various polymerization conditions and their characteristics were compared to each other to determine an optimized polymerization condition. The black polymerized toner prepared at the optimized polymerization condition showed reasonable particle size and shape, and good thermal and printing characteristics by showing its glass transition temperature at $53.6^{\circ}C$.

• Korean Chemical Engineering Research
• /
• v.56 no.2
• /
• pp.156-161
• /
• 2018

$TiO_2$ photocatalyst powders were prepared by chlorination method and sol-gel method. Specific surface area and crystalline (i.e., anatase and rutile) of the catalyst varied depending on manufacture conditions and method. TTIP-sol photocatalyst had higher methylene blue (MB) decomposition characteristics than photocatalyst from chlorination method and TBOT-sol. MB removal efficiency from aqueous solution with TTIP-sol photocatalyst was over 90%. Experimental results showed that the $TiO_2$ photocatalyst with a single anatase phase and a large specific surface area had high decomposition characteristics of organic materials.