• Journal of the Korean Society of Manufacturing Technology Engineers
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• v.21 no.6
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• pp.892-896
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• 2012

CFRP composites with light weight, high strength, and high elasticity by comparing with metal are widely used rather than previous steel plates. However, CFRP composite material has the weakness at hydrothermal and collapsed impact environment. Especially, moisture absorption into composite material can change molecule arrangement and chemical properties under hydrothermal environment. And static collapse experiment is the research in the differences of absorbed energy and deformation mode between moisture and non-moisture absorbed specimens. This study is compared and analyzed on the progress change of moisture absorption ratio after setting up the temperatures of 60 and 80 degrees C in order to comprehend how the change in the temperature influences on moisture absorption status inside CFRP composite materials.

• Archives of Pharmacal Research
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• v.26 no.12
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• pp.1102-1108
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• 2003

We studied the effects of phytolaccosides, saponins from Phytolacca americana, on the intestinal absorption of heparin in vitro and in vivo. The absorption enhancing activity of these compounds (phytolaccosides B, $D_2$, E, F, G and I) was determined by changes in transepithelial electrical resistance (TEER) and the transport amount of heparin disaccharide, the major repeating unit of heparin, across Caco-2 cell monolayers. With the exception of phytolaccoside G, all of them decreased TEER values and increased the permeability in a dose-dependent and time-dependent manner. In vitro, phytolaccosides B,$D_2$, and E showed significant absorption enhancing activities, while effects by phytolaccoside F and I were mild. In vivo, phytolaccoside E increased the activated partial thromboplastin time (APTT) and thrombin time, indicating that phytolaccoside E modulated the transport of heparin in intestinal route. Our results suggest that a series of phytolaccosides from Phytolacca americana can be applied as pharmaceutical excipients to improve the permeability of macromolecules and hydrophilic drugs having difficulty in absorption across the intestinal epithelium.

• Macromolecular Research
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• v.16 no.1
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• pp.21-30
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• 2008

Based on the sheath-core bicomponent composite fibers with modified polystyrene (PS) and the modified polypropylene (PP), composite fibers obtained were further cross-linked and sulphonated with chlorosulphonic acid to produce strong acidic cation ion exchange fibers. The structures of the fibers obtained were characterized using Fourier transform infrared (FT-IR) spectroscopy, differential scanning calorimetry (DSC) etc. The optimal technology of the fibers obtained is discussed. The static absorption capacity of the sheath-core bicomponent composite cation exchange fibers for $Zn^{2+}$, $Cu^{2+}$ was determined. The absorption kinetics and major factors affecting the absorption capacities of $Zn^{2+}$, $Cu^{2+}$ were studied, and its chemical stability and regenerating properties were probed. The results suggest that cation exchange fibers with better mechanical properties and higher exchange capability were obtained. Moreover, this type of ion exchange fiber has good absorption properties and working stability to various metal ions. Hence, they have higher practicability.

• Archives of Pharmacal Research
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• v.25 no.1
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• pp.86-92
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• 2002

The enhancement of paracellular transport of heparin disaccharide using several absorption enhancers across Caco-2 cell monolayers was tested . The cytotoxicity of these enhancers was also examined. The enhancing effects by Quillaja saponin, diponin glycyrrhizinate, $18{\beta}-glycyrrhetinic$ acid, sodium caprate and taurine were determined by changes in transepithelial electrical resistance (TEER) and the amount of heparin disaccharide transported across Caco-2 cell monolayers. Among the absorption enhancers, $18{\beta}-glycyrrhetinic$ acid arid taurine decreased TEER and increased the permeability of heparin disaccharide in a dose-dependent and time-dependent manner with little or negligible cytotoxicity. Our results indicate that these absorption enhancers can widen the tight junction, which is a dominant paracellular absorption route of hydrophilic compounds . It is highly possible that these absorption enhancers can be applied as pharmaceutical excipients to improve the transport of macromolecules and hydrophilic drugs having difficulty in permeability across the intestinal epithelium.

• Archives of Pharmacal Research
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• v.18 no.6
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• pp.427-433
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• 1995

A microscopic mass balance approach has hsown that the initial saturation (Is), absorption number (An), dose number (Do), and dissolution number (Dn) are four fundamental dimensionless parameters that can be used to estimate the fraction dose absorbed (F)l of suspensions of poorly soluble drugs in humans. The dissolution number of a drug increases with decreasing its particle size. The effect of micronization on F for suspensions was investigated in terms of Dn. About 90% of maximal F can be achieved at $Dn{\approx}2$. Increasing the solubility of a drug results in better oral absorption through increasing Dn and decreasing the solubility of a drug results in better oral absorption through increasing Dn and decreasing Do. The fractions dose absorbed of digoxin, griseofulvin, and benoxaprofen agree with predicted F values sorbed by reducing particle size, while absorption of drugs with high Do and low Dn is limited by solubility and requires higher solubility to enhance the fraction dose absorbed in addition to micronization. Solubility at the physiological pH should be used for the estimation of the fraction dose absorbed.

• Korean Chemical Engineering Research
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• v.54 no.5
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• pp.648-652
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• 2016

The study of $CO_2$ absorption in a packed column by 1,1,3,3-tetramethylguanidine (TMG) dissolved in ethylene glycol is presented. Absorption column of inner diameter 1 in and 0.6 m length was filled with Protruded-packing $0.16in{\times}0.16in$. We investigated the effect of operating conditions on overall mass transfer coefficients as well as on $CO_2$ removal efficiency. The loading values reached at about $1.0mol_{CO2}/mol_{TMG}$. In case of absorbent with lean $CO_2$ loading, the overall mass transfer coefficient was proportional to the concentration of TMG. However, in the range of more than ${\alpha}=0.5molCO_2/molTMG$, the overall mass transfer coefficients decreased with the concentration of TMG. It is due to the increasing of mass transfer resistance in liquid phase as increasing of viscosity at higher loading values.

• Journal of the Korean Geographical Society
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• v.50 no.5
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• pp.505-514
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• 2015

This study analyzes a correlation between water content values and chemical index of alteration (CIA) for coarse sedimentary rocks of Mt. Cheonsaeng in Gumi-si, Kyeongsangbuk-do. Through measurement of various water values of 20 samples including water content rate, water absorption rate and equipment measuring we comparatively analyzed the values with CIA of the samples obtained by X-ray fluorescence. As a result of analysis water content rate and water absorption rate in a sedimentary rock are likely to be higher when matrix is psephitic and less compact. Furthermore the higher water content rate is, the higher CIA is due to increase of $SiO_2$ and $Al_2O_3$ and decrease of CaO and $Na_2O$ derived by chemical weathering of felspar. This correlation between water content rate and CIA represents a similar result with previous studies targeting granite.

• Proceedings of the Korean Vacuum Society Conference
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• 2000.02a
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• pp.167-167
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• 2000

전지 재료의 충방전 과정 연구에는 X-선 분말회절(x-ray powder diffraction techniques)과 중성자회절을 많이 사용하였다. 하지만 이러한 분석기술은 long-range order의 구조에 관한 정보를 제공하는데 유용하지만 atomic scale의 구조에 관한 정보를 얻기에는 한계가 있다. Li 전지에서의 전기화학적 반응에서는 cathode 물질에 포함된 전이금속의 산화, 환원 반응에 의한 Li 이온의 intercalation (charge process)과 deintercalation (discharge process) 현상이 일어난다. 이러한 충방전 과정은 알려지지 않은 다양한 형태의 위상 변화를 동반하게 되는데 x-선 이나 중성자를 이용한 powder diffraction techniques 로는 단지 정성적인 결정학적 정보를 얻을 수 있다. 따라서 최근에 원자 단위의 local structure에 관한 정보와 electrochemical state에 관한 정보를 동시에 얻을 수 있는 X-ray Absorption Fine Structure (XAFS) 분석기술을 Li 전지분석에 활용하기 시작하였다. XAFS는 하나의 x-ray 흡수원자에 대해서 주변원자들의 원자구조에 관한 정보와 구성 원소의 electrochemical state에 관한 정보를 얻을 수 있는 분석방법이다. X-ray Induced Electron Emission Spectroscopy (XIEES)는 x-ray에 의해서 방출된 전자를 검출하여 스펙트럼을 얻는 기능을 함축적으로 나타낸 것으로, x-ray를 물질 표면에 조사하여 발생하는 광전자, Auger 전자, 이차전자 등을 전자검출기(Channel Electron Multiplier: CEM)로 검출하는 기능과, 시료를 투과한 x-ray와 시료에서 발생하는 형광 x-ray를 비례계수기로 검출하는 기능을 가지고 있다. 이러한 검출 능력을 바탕으로 EXAFS, XANES, Standing Wave Technique, Elemental Composition Analysis, DXRD, Total Reflection Technique 등을 이용하여 물질을 구성하고 있는 원소의 성분, 미세원자구조, 전자구조에 관한 정보를 얻을 수 있는 새로운 spectrometer이다. 본 연구에서는 자체 개발한 XIEES의 XAFS 기능을 이용하여 여러 가지 방법으로 제조한 LiMn2-xO4와 LiMnO2, MnO2에서 Mn K-absorption edge에 대한 chemical state 변화를 측정하였다. Absorption edge에서 chemical shift를 측정하기 위해서는 방사광 가속기 수준의 에너지 분해능(~0.3eV)이 필요하다. 이번 연구에서는 SiO2(3140) monochromator를 사용하고 여기에 맞는 적절한 parameter를 적용하여 x-ray 에너지 분해능을 포항방사광가속기 수준으로 개선하였다. XIEES에서 얻은 스펙트럼과 포항방사광가속기에서 얻은 스펙트럼을 비교하였다. Chemical shift가 일어나는 경향은 두 실험 결과가 잘 일치하였다.

• Journal of the Korean Institute of Gas
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• v.25 no.3
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• pp.39-45
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• 2021

Scrubbers that treat hazardous materials at workplaces have high treatment efficiency; however, the design is complex, and pumps need to be operated 24 hours a day, which can be costly. Therefore, to minimize the operating costs, small businesses do not install scrubbers, or operate them while circulation pumps are suspended. Hence, this study investigated the application of low-cost, high-performance scrubbers that can be used economically in small businesses. Low-cost, high-efficiency scrubbers are applied to bubble columns to utilize devices for hazardous chemical absorption treatment purposes, and for the development of these scrubbers, absorption performance was reviewed and the optimal application method was studied under certain conditions. The changes in the absorption performance of hazardous gas were studied in certain environments by varying the physical conditions, and the optimal application methods were analyzed. The results showed that, while it was possible to treat some of the gas flowing into the low cost, high performance scrubber, the treatment capacity was reduced. Performance degradation was prevented by supplying an absorption liquid, and a certain level of absorption was maintained depending on the amount of circulation. Based on this, three types of site application methods of low cost, high performance scrubbers were presented. In addition, the appropriate timing of circulation and anti freezing measures were also discussed.

• Korean Chemical Engineering Research
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• v.59 no.2
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• pp.239-246
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• 2021

Characteristics of hydrodynamics and heat absorption by gas in a directly-irradiated fluidized bed particle receiver (50 mm-ID X 150 mm high) of SiC particles have been determined. Solid holdups of SiC particles show almost constant values with increasing gas velocity. Fine SiC particles (SiC II; dp=52 ㎛, ρs=2992 kg/㎥) showed low values of relative standard deviation of pressure drop across bed but high solids holdups in the freeboard region compared to coarse SiC particles (SiC I; dp=123 ㎛, ρs=3015 kg/㎥). The SiC II exhibited higher values of temperature difference normalized by irradiance due to the effect of additional solar heat absorption and heat transfer to the gas by the particles entrained in the freeboard region in addition to the efficient thermal diffusion of the solar heat received at bed surface. Heat absorption rate and efficiency increased with increasing the gas velocity and fluidization number. The SiC II showed maximum heat absorption rate of 17.8 W and thermal efficiency of 14.8%, which are about 33% higher than those of SiC I within the experimental gas velocity range.