• Journal of the Korean Crystal Growth and Crystal Technology
• /
• v.15 no.5
• /
• pp.193-197
• /
• 2005

CuO has been synthesized using the layered organic-inorganic hybrids, $Cu_2(OH)_3(CH_3COO){\cdot}H_2O$ as precursor. The simple thermal decomposition of $Cu_2(OH)_3(CH_3COO){\cdot}H_2O$ is used without any external organic templates. This method provides large-scale production at a low cost of the single-crystalline CuO particles. The morphology of CuO aggregated particles is strongly dependent on structure of the precursor.

• Bulletin of the Korean Chemical Society
• /
• v.34 no.8
• /
• pp.2473-2479
• /
• 2013

The kinetics of the radical-polar molecule reaction $CH_3+HBr{\rightarrow}CH_4+Br$ has been studied at temperatures between 150 and 1000 K using classical dynamics procedures. Potential energy surfaces constructed using analytical forms of inter- and intramolecular interaction energies show a shallow well and barrier in the entrance channel, which affect the collision dynamics at low temperatures. Different collision models are used to distinguish the reaction occurring at low- and high-temperature regions. The reaction proceeds rapidly via a complex-mode mechanism below room temperature showing strong negative temperature dependence, where the effects of molecular attraction, H-atom tunneling and recrossing of collision complexes are found to be important. The temperature dependence of the rate constant between 400 and 1000 K is positive, the values increasing in accordance with the increase of the mean speed of collision. The rate constant varies from $7.6{\times}10^{-12}$ at 150 K to $3.7{\times}10^{-12}$ at 1000 K via a minimum value of $2.5{\times}10^{-12}\;cm^3\;molecule^{-1}\;s^{-1}$ at 400 K.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.06a
• /
• pp.394-395
• /
• 2006

본 연구에서는 Arachidic acid Langmuir-Blodgett (LB) 막의 표면이미지와 전압-전류 특성을 측정하였다. Arachidic acid는 포화지방산으로 ($CH3(CH_2)_{18}$ COOH)의 구조를 가지며, 크기가 $27.5\;{\AA}$으로 $CH_3(CH_2)_{18}$의 소수기와 COOH의 친수기로 구성되어 있어, LB Trough를 사용하여 박막제작과 분자제어가 쉽다. Chloroform을 용매로 하여 2mmol/l의 농도를 조성하여 ${\pi}$-A 등온선을 통해 기체 상태, 액체 상태, 고체 상태를 관찰하였다. LB막의 제작 및 평가에서 막의 안정성은 ${\pi}$-A곡선, AFM (Atomic force microscopy) 등을 통하여 확인 하였다. 또한 LB 막을 Metal/LB막/Metal 구조의 소자로 제작하여 전압-전류 특성을 측정하였다.

• Preventive Nutrition and Food Science
• /
• v.3 no.2
• /
• pp.111-118
• /
• 1998

To develop a simple, rapid and simultaneous analytical method of phenolic compounds using gas chromatography (GC) and gas chromatography/mass spectrophometer (GC/Ms), this experiment was carried out to search the retention times of capillary columns and the characteristics of fragment ions in electron impact mass spectra. Most of trimethylsilyl derivatives and underivatized phenolic compounds were separated very well on three kinds of capillary columns(HP-1), Ultra-2 and HP-35). Quantitiative determination of phenolic compounds was achieved by internal standards (p-hydroxybenzoic acid iopropyl ester, p-hydroxybenzoic acid ethyl ester). Calibration plts were linear in the investigated range, and the limits of detection were about 5 ng at split mode method. When analyzed by three columns, theseparation times were fairly constant on two nonpolar columns, but a few compounds showed slightly different separation order by the itnermediate polar HP-35 column. The important characteristic patterns of TMS derivatives of phenolic compounds on the EI/MS spectrra appeared at the base peak of [M-15]+ ion and presented at high abundance in most TMS derivatives of phenoloc compounds. [M]+, [M-CH3-COO]+, [M-Si(CH3)4]+ and [M-Si(CH3)4 -CH3]+ also observed in mass spectra of these compounds . Although several compounds have the same retention times on GC column, it might be possible to identify these compounds by the different patternsof mass frgement ions. The TMS derivatives, thus , provide additional information for identification of phenolic compounds in biological systems.

• Advances in environmental research
• /
• v.9 no.2
• /
• pp.123-133
• /
• 2020

A time series dataset was conducted to ascertain the effect of water table on the variability in and emission of CH₄ and CO₂ concentrations at a closed landfill site. An in-situ data of methane/carbon dioxide concentrations and environmental parameters were collected by means of an in-borehole gas monitor, the Gasclam (Ion Science, UK). Linear regression analysis was used to determine the strength of the correlation between ground-gas concentration and water table. The result shows CH₄ and CO₂ concentrations to be variable with strong negative correlations of approximately 0.5 each with water table over the entire monitoring period. The R² was slightly improved by considering their concentration over single periods of increasing and decreasing water table, single periods of increasing water table, and single periods of decreasing water table; their correlations increased significantly at 95% confidence level. The result revealed that fluctuations in groundwater level is the key driving force on the emission of and variability in groundgas concentration and neither barometric pressure nor temperature. This finding further validates the earlier finding that atmospheric pressure - the acclaimed major control on the variability/migration of CH₄ and CO₂ concentrations on contaminated sites, is not always so.

• KOREAN JOURNAL OF PACKAGING SCIENCE & TECHNOLOGY
• /
• v.27 no.1
• /
• pp.35-40
• /
• 2021

Calcium hydroxide (CH) reacts with CO2 to produce moisture, and sodium carbonate (SC) reacts with CO2 in the presence of moisture. Using these different characteristics of these two reactants, a CH/SC mixture of CO2 absorber tuned for kimchi ripening to produce CO2 in a flexible package was selected. A ratio of CH:SC (1:2) in highly gas permeable microporous spunbonded film (Tyvek) sachet was found to be appropriate for delayed and consistent CO2 absorption useful for kimchi package. Addition of superabsorbent polymer (SAP) as moisture buffer was helpful for boosting the consistency of CO2 absorption. In a package of 0.5 kg kimchi at 10℃, the sachet consisting of 0.794 g of CH + 2.276 g of SC + 0.4 g of SAP suppressed its volume expansion and maintained a suitable range of CO2 partial pressure (PCO2) steadily inside. These optimal conditions may vary depending on the type and salinity of kimchi, storage and distribution temperature, and the material and area of the absorber sachet. This study showed a potential of mixture CO2 absorber to be tuned for CO2 producing packaged kimchi for the purpose of keeping consistent PCO2 at tolerable volume expansion.

• Transactions of the Korean Society of Automotive Engineers
• /
• v.9 no.5
• /
• pp.188-194
• /
• 2001

Metal matrix composites with whisker reinforcements have significant potential for demanding mechanical applications including defense, aerospace, and automotive industries. Especially, metal matrix composites, which are reinforced with aluminum borate whisker, have been used for the part of piston head in automobile because of good specific strength and wear resistance. Aluminum alloy-based metal matrix composites with whisker reinforcements have been produced using squeeze casting method, which is kind of an infiltration method. In this study, AC4CH-based metal matrix composites with $Al_{18}B$_4$O_{33}$ reinforcement have been produced using squeeze casting method, after T6 heat treatment, we evaluated mechanical properties of matrix and MMC composite were evaluated.

• Journal of ILASS-Korea
• /
• v.7 no.4
• /
• pp.42-49
• /
• 2002

In this study, quantitative measurement of nitric oxide concentration distributions were investigated in the laminar CH4/O2/N2 premixed flame by laser-induced fluorescence (LIF). The NO A-X (0,0) vibrational band around 226nm was excited using a XeCl excimer-pumped dye laser. Selecting an appropriate NO transition minimizes interference from Rayleigh scattering and O2 fluorescence. The measurements were taken in CH4/O2/N2 premixed flame with equivalence ratios varying from $1.0{\sim}1.6$, and a fixed flowrate of 5slpm. NO was found to produce primarily between an inner premixed and an outer nonpremixed flame front, and total NO concentration is raised when equivalence ratios increase. These results suggest that prompt NO is likely to contribute to NO formation in CH4/O2/N2 premixed flame. Furthermore, this trend was well matched with previous works.

• Journal of the Korean Chemical Society
• /
• v.12 no.4
• /
• pp.155-159
• /
• 1968

On the extraction of humic acid from peat, the optimum conditions were studied and the effects of them on the characteristics of humic acid were also examined by means of infrared spectroscopy. 1. Pretreatment of peat with diluted 6-8% HCl solution for 5 hrs. prior to extraction with alcohol-benzol azeotropic mixture have resulted the better yield of humic acid. The water soluble Na-humates were obtained by the subsequent extraction with one hundred times quantity of caustic soda solutieon for 1hr. at 90 $^{\circ}C$. Thus the pure humic acids have been yielded approximately 40% (by wt.) from the raw peat. 2. In characteristics of humic acid, the chemical structure, mainly the contents of such functional groups as -COOH, -OH (phenol type), $-CH_2CO-$, $-CH_2{\cdot}O{\cdot}CH_2-$ and aromatic rings were varied according to the concentration of alkaline solution, temperature and time when the humic acids were extracted with alkali.

• Journal of the Korean Society of Clothing and Textiles
• /
• v.36 no.12
• /
• pp.1257-1269
• /
• 2012

The dyeing behaviors of berberine chloride, palmatine chloride hydrate, and Phellodendron bark extract on silk fabric were investigated to evaluate palmatine as another chromophoric substance of Phellodendron bark. The dyeing conditions were composed of combinations of pH (3, 5, 7, 9), temperature (10, 30, 55, $80^{\circ}C$), and time (10, 30, 60 min). The results indicate that palmatine was comparable to berberine in the dyeing behaviors tested for this study and the results were statistically significant. The dye exhaustion and dye uptake of palmatine-CH were slightly lower than berberine-C, which however were not statistically significant. Similar to berberine-C, palmatine-CH favored a pH 7 condition for both dye exhaustion and dye uptake. However, palmatine-CH favors a higher dyeing temperature and longer dyeing time than berberine-C for superior dyeing results.