• Composites Research
• /
• v.31 no.2
• /
• pp.43-50
• /
• 2018

The effects of deposition temperature on chemical vapor deposited silicon carbide (CVD-SiC) were studied to obtain high deposition rates and excellent bending strength characteristics. Silicon carbide prepared at $1250{\sim}1400^{\circ}C$ using methyltrichlorosilane(MTS : $CH_3SiCl_3$) by hot-wall CVD showed deposition rates of $95.7{\sim}117.2{\mu}m/hr$. The rate-limiting reaction showed the surface reaction at less than $1300^{\circ}C$, and the mass transfer dominant region at higher temperature. The activation energies calculated by Arrhenius plot were 11.26 kcal/mole and 4.47 kcal/mole, respectively. The surface morphology by the deposition temperature changed from $1250^{\circ}C$ pebble to $1300^{\circ}C$ facet structure and multi-facet structure at above $1350^{\circ}C$. The cross sectional microstructures were columnar at below $1300^{\circ}C$ and isometric at above $1350^{\circ}C$. The crystal phases were all identified as ${\beta}$-SiC, but (220) peak was observed from $1300^{\circ}C$ or higher at $1250^{\circ}C$ (111) and completely changed to (220) at $1400^{\circ}C$. The bending strength showed the maximum value at $1350^{\circ}C$ as densification increased at high temperatures and the microstructure changed from columnar to isometric. On the other hand, at $1400^{\circ}C$, the increasing of grain size and the direction of crystal growth were completely changed from (111) to (220), which is the closest packing face, so the bending strength value seems to have decreased.

• Clean Technology
• /
• v.18 no.4
• /
• pp.379-389
• /
• 2012

Environmental issues are being paid more attention due to income growth, urban overcrowding, and population growth in Korea. Among the various environmental problems, odor damage is the one of the serious factors. To take example for food waste combination treatment in Su-young wastewater treatment plant in Busan, many complaints occurred because this plant locate around residential areas. The purpose of this work is not only to analyze odorous elements and their contributions but also to evaluate odor quotient (OQ), sum of odor quotient (SOQ), and treatment efficiency of bio-filter. The results of dilution sensory test of complex odor, grinder, leachate, hopper indicated higher order complex odors happen in July and August. The main odorous elements consisted of hydrogen sulfide, ammonia, methly mercaptan and acetaldehyde, which were analyzed by instrumental detection method, and methyl mercaptan was exceeded over 3,571 times of threshold. In addition, result of contribution of odor was methyl mercaptan (49.95 to 59.08%), hydrogen sulfide (20.43 to 29.27%), trimethylamine (8.82 to 13.42%) and acetaldehyde (9.17 to 11.35%). Other facilities were compared with the contribution of the odor using OQ and SOQ during the process. Sulfur compounds, acetaldehyde, and trimethylamine are high contribution of odor using OQ as well as odor intensity of grinding process is highest. As a result, sulfur compounds (e.g., methyl mercaptan and hydrogen sulfide) are highest for OQ and SOQ of grinding process is highest as 7,067. The removal efficiency of deodorization equipment was more than 90.00% in ammonia and amines, but the average efficiency of sulfur compounds was 53.51%. Thus, this facility is more higher contribution of acetaldehyde and trimethylamine than other treatment facilities. And food waste treatment in environmental area needs to consider appropriate capacity and refers to other bio-filter operating conditions.

• Journal of the Mineralogical Society of Korea
• /
• v.16 no.1
• /
• pp.107-123
• /
• 2003

The objective of this study was to investigate mineral precipitates, which derived from the zero valent iron (ZVI) corrosion during TCE dechlorination and to find the controlling factors in mineral precipitates. A series of column experiemnts were conducted to evaluate the location of ZVI and the effects of electrode arrangements in electro-enhanced permeable reactive barrier (E2PRB) systems. Based on mineralogical study, ZVI samples near the influent port had more lepidocrocite, ferrihydrite or Fe (oxy)hydroxide, and (phospho)siderite while backward samples had more akaganeite, magnetite/maghemite, and intermediate green rust (GR) I and GR II. A suite of mineral distribution was preferabley related to the dissolved oxygen and the increased pH. Controlling factors of mineral precipitates in an E2PRB system were found to be (1) pH, (2) dissolved oxygen, (3) the types of Fe intermediates, and (4) anionic species to form complex strongly.

• Journal of the Korean Applied Science and Technology
• /
• v.32 no.1
• /
• pp.56-61
• /
• 2015

In this study, the current-voltage curves for the SCM440 steel by the addition of an organic corrosion inhibitor triethanolamine(TEA) was measured using the conventional three electrodes of cyclic voltammetry. As a result, the C-V characteristics of SCM440 steel were to be for an irreversible process due to the oxidation current from the cyclic voltammetry. Diffusion coefficient according to the twice increasing the concentration of TEA in the corrosion inhibitor from $2.5{\times}10^{-4}M$ to $5.0{\times}10^{-4}M$, the diffusion coefficient was found to be a good corrosion-inhibiting effect is reduced by 1.5 times, so for each $2.561{\times}10^{-6}cm^2s^{-1}$ to $1.707{\times}10^{-6}cm^2s^{-1}$. When according to the electrolyte concentration and the effect is to increase the electrolyte concentration to 1.0 N at 0.5 N, the diffusion coefficient is $2.56{\times}10^{-6}cm^2s^{-1}$ to $5.12{\times}10^{-6}cm^2s^{-1}$, each 2 times decrease in the use of the electrolyte of 1.0 N, because this was more appropriate.

• Journal of the Korean Institute of Gas
• /
• v.22 no.5
• /
• pp.107-113
• /
• 2018

While accident data are used to show alertness to accidents or to review similar cases, the analysis of nature of accident data its association with surrounding environment is very insufficient. Therefore, it is very necessary to demonstrate the possibility of an accident for a particular region by developing analysis techniques with the related accident data. The purpose of this study is to develop an analysis model and implement a system that produces regional accident probability based on historical weather information data and accident and reporting data. In other words, the system is designed and developed to create models by k-NN and decision tree algorithms with optional user-environment variables based on the probability between weather and accidents about many particular region of Korea. In the future, the models developed in this study are intended to be used to analyze and calculate the risk of a more narrow area.

• Korean Journal of Food Science and Technology
• /
• v.26 no.5
• /
• pp.479-483
• /
• 1994

The effects of the different protein source on serum cholesterol levels were studied in SD strain male rats. Fish protein prepared by the method of SUZUKI from Alaska Pollack (Theragra chalcogramma) was compared with casein and soybean protein isolate. Each protein source was incoporated into a cholesterol-free diet in order to provide a protein level of 20% for 2 weeks. The result obtained are as followed: Concentration of total-cholesterol, LDL-cholesterol, total-cholesterol/HDL-cholesterol and triglyceride in rats fed with fish protein group were significantly lower than those of rats fed with casein and similar to those of rats fed with soybean protein. In addition, it was shown that the ratio of Lys/Arg and Gly/Met+Cys of fish protein was close to that of soybean protein.

• Polymer(Korea)
• /
• v.35 no.4
• /
• pp.342-349
• /
• 2011

The effect of the amount of vinyltriethoxysilane (VTEOS) in precipitated silica filled silicone rubbers was extensively investigated in terms of the change of mechanical properties, heat resistance, oil resistance, compression set, resilience, and curing characteristics. As the content of VTEOS increased from 0 to 2.0 phr, the hardness of the silicone rubber increased, however, tensile strength, elongation at break, and tear strength decreased. From heat resistance test, the change of mechanical properties was pronounced for silicone rubber treated with more VTOES. The best heat resistance was achieved at 2.0 phr VTOES. In addition, oil resistance was proportionally improved with VTEOS content. From oil resistance test. it was found that the decrease in hardness and maximum elongation was reduced for VTEOS-added systems. Finally, resilience, compression set, degree of cure and crosslink density were significantly enhanced with the amount of VTEOS.

• Journal of KIISE:Software and Applications
• /
• v.27 no.8
• /
• pp.855-863
• /
• 2000

Although Behavior-Knowledge Space (BKS) method, one of well known decision combination methods, does not need any assumptions in combining the multiple experts, it should theoretically build exponential storage spaces for storing and managing jointly observed K decisions from K experts. That is, combining K experts needs a (K+1)st-order probability distribution. However, it is well known that the distribution becomes unmanageable in storing and estimating, even for a small K. In order to overcome such weakness, it has been studied to decompose a probability distribution into a number of component distributions and to approximate the distribution with a product of the component distributions. One of such previous works is to apply a conditional independence assumption to the distribution. Another work is to approximate the distribution with a product of only first-order tree dependencies or second-order distributions as shown in [1]. In this paper, higher order dependency than the first-order is considered in approximating the distribution and a dependency-based framework is proposed to optimally approximate the (K+1)st-order probability distribution with a product set of dth-order dependencies where ($1{\le}d{\le}K$), and to combine multiple experts based on the product set using the Bayesian formalism. This framework was experimented and evaluated with a standardized CENPARMI data base.

• Journal of Life Science
• /
• v.18 no.6
• /
• pp.814-825
• /
• 2008

Ascochlorin (ASC) is prenyl-phenol compound that was isolated from the fungus Ascochyta viciae. ASC reduces serum cholesterol and triglyceride levels, and suppresses hypertension, tumor development, ameliorates type I and II diabetes. Here, to better understand the mechanisms by which ASC regulates physiological or pathological events and induces responses in the pharmacological treatment of inflammation, we performed differential analysis of the proteome of the mouse macrophage RAW264.7 cells in response to ASC. In this study, we used a proteomic analysis of LPS-induced RAW264.7 cells treated by ASC, to identify proteins potentially involved in inflammatory processes. The RAW264.7 cell proteomes with and without treatment with ASC were compared using two-dimensional electrophoresis (2-D SDS-PAGE), matrix-assisted laser desorption/ionization mass spectrometry (MALDI-TOF-MS) and bioinformatics. The largest differences in expression were observed for the calreticulin (4-fold decrease), ${\beta}-actin$ (4-fold decrease) and vimentin (1.5-fold decrease). In addition, rabaptin was increased 3-fold in RAW264.7 cells treated with ASC. The expression of some selected proteins was confirmed by RT-PCR analysis.

• Fashion & Textile Research Journal
• /
• v.15 no.6
• /
• pp.985-992
• /
• 2013

Polytrimethylene terephthalate(PTT) offers several advantageous properties such as good tensile strength, uniformity, stiffness, toughness, UV stability, resilience, stain resistance, outstanding elastic recovery, and dyeability. The effects of annealing temperature on physical properties and the structure of PTT filaments and yarn were investigated by measuring wide-angle X-ray diffraction (WAXD), density, optical birefringence, dynamic visco elasticity, and tensile testing. The intensity of maximum tan ${\delta}$ decreased and the temperature of maximum tan ${\delta}$ shifted to a higher temperature as the annealing temperature of filaments increased; however, it shifted to a lower temperature when the annealing temperature exceeded $130^{\circ}C$. In addition, crystallinity, density and D-spacing of (010) crystal face increased as the annealing temperature increased. Optical birefringence and specific stress were almost constant up to $100^{\circ}C$ and then decreased above $130^{\circ}C$. The shrinkage of PTT filament is 0 in boiling water when annealed above $130^{\circ}C$; consequently, the use of annealed fiber above $130^{\circ}C$ can remove thermal instability when dyeing PTT fiber. In the case of yarns, the thermal stability and physical properties of yarns showed the best effect when the ply number is less than 5, twist number is less than 400tpm, and the annealing time is 20minutes.