• Journal of the Society of Cosmetic Scientists of Korea
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• v.19 no.1
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• pp.1-19
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• 1993

Gas chromatography serves to separate the mixtures into its components, and mass spectrometer is used to analyzing of unknown compounds. But there are many problems the identification of horn compounds using by GC only. As this reason GC/MS a very powerful analyzing technique. Mass spectrometer consists of 1) inlet stem 2) ion source 3) Bass filter 4) detectors and 5) data system. There are two analyzing modes in the GC/MS, those are scan and SIM(selected ion mom toping) modes. Scan mode is used when analyzing unknown compounds and SIM mode al lows the mass spectrometer to detect specific compound with very high sensitivity. As GC/MS applications for the analysis of cosmetic products, volatile compounds in lotion, earn foundation and hair color, and carbon distribution of fatty acids in soap were performed. Also as a new sample pre-treatment technique, head space sampler/GC/MS introduced in order to analyze the volatile compounds in a toothpaste.

• Membrane Journal
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• v.27 no.6
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• pp.469-476
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• 2017

Membrane separation is a technology of low energy consumption. Membranes made of zeolites are of great interest because their fixed and open pores in the size of small molecules inside crystalline structures allow separation processes under harsh conditions. While zeolite NaA (LTA-type) is industrially used for dewatering of organic solvents, its pore size and thermal and hydrothermal stability can be tuned by exchange of framework and extra-framework elements. SOD with pores of only 0.28 nm is of great interest for $H_2$- und $H_2O$-separation and also can be tuned by ion exchange. Zeolites open the opportunity to create membranes of adapted separation behavior for small molecules in conditions of surrounding technical processes.

• Journal of Environmental Science International
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• v.11 no.3
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• pp.215-225
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• 2002

In order to evaluate the relationship between geochemical characteristics and benthic facies of the sediments from the Oenaro Island where red tide proliferation is first observed every year including this year, surface and short multiple core sediment samples were analyzed in terms of geochemical and benthic facies variation. The contents of organic carbon, carbonate, and sulfide gas were relatively low. The variation in C/N ratios, which indicate nature of organic carbon, suggested that the organic carbon recorded in the study area is composed of mixtures of marine and terrigenous organic matters. The concentration of minor elements found at the surface and multiple core sediment samples were also low as well as the enrichment factors(Ef) for the seven heavy metals indicated that the sediment of this area is not polluted significantly. The macrobenthic faunal community comprised 61 species, and their mean density was 708 ind./m2. Polychaete worms were major taxa of this benthic community. A crustacean amphipod, Melita sp. was the most abundant species accounted for 20.7% of total abundance, and the small polychaetes such as Heteromastus filiformis, Paralacydonia poradoxa, Magelona japonica and Sigambra tentaculata were the next dominant species. The macrobenthos around the Oenaro Island were more diverse and abundant than that in Gamak Bay. The benthic communities in the study area sustained somewhat different species composition based on the cluster analysis and the MDS ordination. The benthic community health condition at three stations seemed to be unbalanced, and slightly polluted based on the biological index such as BPI and BC. There was no clear relationship between the geochemistry characteristic and the benthic faunal facies attributed by the micro-algal blooms in this coastal area.

• Journal of the Korean Society of Combustion
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• v.18 no.2
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• pp.32-41
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• 2013

This study presents both experimental and numerical investigation of ignition delay time of n-heptane and n-butanol binary fuel. The $O_2$ concentration in the mixture was set to 9-10% to make high exhaust gas recirculation( EGR) rate condition which leads low NOx and soot emission. Experiments were performed using a rapid compression machine(RCM) at compressed pressure 20bar, several compressed temperature and three equivalence ratios(0.4, 1.0, 1.5). In addition, a numerical study on the ignition delay time was performed using CHEMKIN codes to validate experimental results and predict chemical species in the combustion process. The results showed that the ignition delay time increased with increasing the n-butanol fraction due to a decrease of oxidation of n-heptane at the low temperature. Moreover, all of the binary fuel mixtures showed the combustion characteristics of n-heptane such as cool flame mode at low temperature and negative-temperature-coefficient(NTC) behavior. Due to the effect of high EGR rate condition, the operating region is reduced at lean condition and the ignition delay time sharply increased compared with no EGR condition.

• Transactions of the Korean Society of Automotive Engineers
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• v.8 no.2
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• pp.19-26
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• 2000

This paper presents the effects of initial pressure of mixture on CO, $CO_2$ and NOx emissions in constant volume combustion chamber. The CO, $CO_2,O_2,N_2$ concentrations in the chamber are determined by thermal conductivity detection (Gas-chromatograph) wile the NOx concentration is measured by chemiluminescent detection (NOx Analyser). Methane-air mixture is used as premixed fuel and the measurements are taken with equivalence ratios($\phi$) varing from 0.6 to 1.3, and initial pressures of methane-air mixture varing from 0.1MPa to 0.8MPa in constant volume combustion chamber. The NOx concentration steadily increases with increasing equivalence ratio, peaks in lean flame ($\phi$=0.85~0.9), and then rapidly decreases. However, as the initial pressure of mixture is increased, the equivalence ratio corresponding to the point of peak [NOx] shifts towards leaner conditions. This is caused by a similar shift in the peak [CH], which is caused by the variation with pressure and equivalence ratio of the rate of CH production from $CH_2$ and OH. The maximum combustion pressure peaks at $\phi$ =1.05 and the $CO_2$ concentration peaks at $\phi$=0.95~1.0 while the CO concentration rises sharply at the condition of fuel-rich mixtures. This is caused by complete combustion at $\phi$=0.95.

• Korean Journal of Materials Research
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• v.19 no.1
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• pp.37-43
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• 2009

Silicon dioxide as gate dielectrics was grown at $400^{\circ}C$ on a polycrystalline Si substrate by inductively coupled plasma oxidation using a mixture of $O_2$ and $N_2O$ to improve the performance of polycrystalline Si thin film transistors. In conventional high-temperature $N_2O$ annealing, nitrogen can be supplied to the $Si/SiO_2$ interface because a NO molecule can diffuse through the oxide. However, it was found that nitrogen cannot be supplied to the Si/$SiO_2$ interface by plasma oxidation as the $N_2O$ molecule is broken in the plasma and because a dense Si-N bond is formed at the $SiO_2$ surface, preventing further diffusion of nitrogen into the oxide. Nitrogen was added to the $Si/SiO_2$ interface by the plasma oxidation of mixtures of $O_2/N_2O$ gas, leading to an enhancement of the field effect mobility of polycrystalline Si TFTs due to the reduction in the number of trap densities at the interface and at the Si grain boundaries due to nitrogen passivation.

• Journal of the Korean Society of Industry Convergence
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• v.23 no.4_2
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• pp.617-626
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• 2020

The drilling mud is essentially used in oil and gas development. There are several roles of using the drilling mud, such as cleaning the bottomhole, cooling and lubricating the drill bit and string, transporting the cuttings to the surface, keeping and adjusting the wellbore pressure, and preventing the collapse of the wellbore. The fragments from rocks and micro-sized bubbles generated by the high pressure are mixed in the drilling mud. The systems to separate those mixtures and to keep the uniformly maintained quality of drilling mud are required. In this study, the simulation is conducted to verify the performance of the mud tank's agitation capacity. The primary role of the mud tank is the mixing of mud at the surface with controlling the mud condition. The container type is chosen as a mud tank pursuing efficient transport and better management of equipment. The single- and two-phase simulations about the agitation in the mud tank are performed to analyze and identify the inner flow behavior. The convergence of results is obtained for the vertical- and axis-direction velocity vector fields based on the grid-dependency tests. The mixing time analysis depending on the multiphase flow conditions indicates that the utilization of a two-stepped impeller with a smaller size provides less time for mixing. This study's results are expected to be utilized as the preliminary data to develop the mixing and integrating equipment of the onshore drilling mud system.

• Korean Journal of Materials Research
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• v.31 no.9
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• pp.532-538
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• 2021

In this study, a spray dryer is used to make granules of Y₂O₃ and YF₃, and then Y₅O₄F₇ is synthesized following heat treatment of them under Ar gas atmosphere at 600 ℃. Single and binary monomer mixtures are compared and analyzed to optimize photocurable monomer system for DLP 3D printing. The mixture of HEA and TMPTA at 8:2 ratio exhibits the highest photocuring properties and low viscosity with shear thinning behavior. The optimized photocurable monomer and synthesized Y₅O₄F₇ are therefore mixed and applied to printing process at variable solid contents (60, 70, 80, & 85 wt.%) and light exposure times. Under optimal light exposure conditions (initial exposure time: 1.2 s, basic exposure time: 5 s), YOF composites at 60, 70 & 80 wt.% solid contents are successfully printed. As a result of measuring the size of the printed samples compared to the dimensions of the designed bar type specimen, the deviation is found to increase as the YOF solid content increases. This shows that it is necessary to maximize the photocuring activity of the monomer system and to optimize the exposure time when printing using a high-solids ceramic slurry.

• Design & Manufacturing
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• v.13 no.2
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• pp.37-43
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• 2019

This study conducted a research as to condensation heat transfer friction loss headby using three types of flat micro multi-channel tubes with different processing of micro-fin and number of channels inside the pipes and different sizes of appearances. In addition, identical studies were conducted by using smoothing circular tubes with 5mm external diameter to study heat enhancement factor and pressure drop penalty factor. 1) The friction head loss showed an increase as the vapor quality and mass flux increased. In case of saturation temperature, it shows an increase as it gets lower. These factors are the reason occurring as the lower the saturation temperature is, the higher the density of refrigerant vapor gets. The influence of heat flux is similar as the dryness is low, but as it gets higher, it lowers in heat flux, and as the high temperature of high heat flux, it is a factor that occurs as the density gets lower. 2) RMS error of the in case of friction head loss, it showed to be predicted as 0.45~0.67 by Chisholm, Friedel, Lockhart and Martinelli. 3) As forfriction head loss penalty factor, the smaller the aspect ratio is, the larger the penalty factor gets, and as for the effect of micro-fin, the penalty factor increased because it decreases to the gas fluid the way groove for the refrigerant's flow.

• Entomological Research
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• v.48 no.6
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• pp.490-498
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• 2018

Ruspolia differens (Serville) (Orthoptera: Tettigoniidae) is a highly valued edible grasshopper species in Africa. However, the effects of plant diets on lipid content and fatty acid composition of R. differens are not well understood. We tested the effects of four diets on the total lipid content and fatty acid composition of R. differens. Sixth instar nymphs of R. differens were reared on one, and mixtures of two, three, and six natural plant inflorescences. Individuals collected from the field constituted a control treatment. We extracted lipids and analyzed the fatty acid methyl esters using gas chromatography-mass spectrometry. We analyzed if the total lipid content, body weight, and fatty acid composition differed among diets and between the sexes using two-way ANOVAs and a PERMANOVA model, respectively. The total lipid content and weight of R. differens did not differ among the diets. The nine common fatty acids were palmitic (mean across treatments, 26%), oleic (22%), palmitoleic (18%), linoleic (13%), stearic (7%), myristic (6%), myristoleic (4%), ${\alpha}$-linolenic (2%) and arachidic acid (1%). The composition of fatty acids and the proportion of essential fatty acids significantly differed among the diets. The proportion of essential fatty acids was highest in the control treatment (21%) but low in less diversified (one to three feed) diets (12-13%). This study demonstrates that the fatty acid composition in R. differens can be influenced through diet. Thus, with dietary manipulations, using local plants in Africa, it is possible to produce R. differens with preferred high quality essential fatty acids for human consumption.