• Journal of Ginseng Research
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• v.3 no.1
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• pp.66-93
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• 1979

Panax ginseng C. A. Meyer, which has been known for more than EWO years. occupies a Particular prince in folk medicine as so called tonic remedy. The pharmacolgical investigations of ginseng, based on the scientific concepts and methodology, have been performed by many researchers through the past 50∼60 years at different parts of the world. The pharmacological action of Panax ginseng compiled from the numerous reports can be summarized as follows: 1. On central nervous system, the effect of Panax ginseng is timulatory in smaller doses and somewhat depressive in larger doses. From the psychopharmacological aspect, ginseng seems to increase the mental efficiency of man. 2. Ginseng has the effect tending to Protect organism from various physical and chemical stresses. 3. The growth and basal metabolic rates of experimental animals are stimulated by ginseng. Ginseng also prolongs the survival time of animals under adverse influences. 4. Increasing the physical and mental efficiency, ginseng postpones the onset of fatigue and increases the working capacities. 5. In the case of the intravenous administration of ginseng, a transitory and slight hypotensive effect is observed. These hypotensive effects seems to include that of a direct action and actions related to the release of histamine and/or serotonin by ginseng. 6. It is Presumed that ginseng lowers the elevated bleed ingar and cholesterol level. 7. Ginseng tends to increase the gastrointestinal motizity and tone 8. It is presumed that ginseng Promotes the iron metabolism and activates the hematopoietic factors. 9. Ginseng tends to stimulate the biosynthesis of nucleic acid and release of histamine and serotonin. 10. The toxicity end adverse reactions of ginseng appear to be nothing that warrants apprehension. 11. Anticancer erects of ginseng seem to be due to indirect action rather than direct action on cancer cell, by improving the host condition 12. Recent clinical trials of ginseng harts obtained sent good results, but Present trial is still limited in its range, so it is necessary to broaden the scope of trial covering many kinds of organs and diseases. From the above, although it appears that substantial advancements have been achieved in the studies on the Pharmacological actions of Panax ginseng there are many discrepancies noticed in the reported data. Furthermore the precise mechanisms of actions of ginseng are sometimes obscure, even unknown in other actions as the students stand now. The main reasons for this are considered to be that even though saponin has been identified at one of the active substances of ginseng, other components have not fully been identified and that the experimental approaches of the investigations varied with different researchers. Thus a thorough analysis of the chemical components and newer standardized concepts and metohds appear to be the pre-requisites for further study of the pharmacolgical effects and mechaisms of Panax ginseng.

• Journal of Hydrogen and New Energy
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• v.27 no.3
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• pp.276-282
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• 2016

The effects of conductive additives in a $La_{0.8}Sr_{0.2}MnO_3$ perovskite bifunctional electrode for oxygen reduction reaction (ORR) and oxygen evolution reaction (OER) were investigated in an alkaline solution. Highly porous carbon black (CB) and Ni powder were added to the bifunctional electrodes as conductive additives. The surface morphologies of electrodes containing CB and Ni were observed by scanning electron microscopy (SEM). The current densities for both ORR and OER were changed by the addition of CB. The conductive additive changed physical properties of bifunctional electrodes such as the sheet conductance, gas permeability and contact angle. It was observed that the air permeability of electrode was most effective to enhance the currents for ORR and OER.

• Korean Journal of Soil Science and Fertilizer
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• v.48 no.5
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• pp.351-360
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• 2015

Human influence on soil formation has dramatically increased with human civilization and industry development. Increase of anthropogenic soils induced researches on the anthropogenic soils; classification, chemical and physical characteristics of anthropogenic soils and plant growth from anthropogenic soils. However there have been no comprehensive analyses on soil pore or physical properties of anthropogenic soils from 3 dimensional images in Korea. The objectives of this study were to characterize physical properties of anthropogenic paddy field soils by depth and to find differences between natural and anthropogenic paddy field soils. Soil samples were taken from two anthropogenic and natural paddy field soils; anthropogenic (A_c) and natural (N_c) paddy soils with topsoil of coarse texture and anthropogenic (A_f) and natural (N_f) paddy soils with topsoil of fine texture. The anthropogenic paddy fields were reestablished during the Arable Land Remodeling Project from 2011 to 2012 and continued rice farming after the project. Natural paddy fields had no artificial changes or disturbance in soil layers up to 1m depth. Samples were taken at three different depths and analyzed for routine physical properties (texture, bulk density, etc.) and pore properties with computer tomography (CT) scans. The CT scan provided 3 dimensional images at resolution of 0.01 mm to calculate pore radius size, length, and tortuosity of soil pores. Fractal and configuration entropy analyses were applied to quantify pore structure and analyze spatial distribution of pores within soil images. The results of measured physical properties showed no clear trend or significant differences across depths or sites from all samples, except the properties from topsoils. The results of pore morphology and spatial distribution analyses provided detailed information of pores affected by human influences. Pore length and size showed significant decrease in anthropogenic soils. Especially, pores of A_c had great decrease in length compared to N_c. Fractal and entropy analyses showed clear changes of pore distributions across sites. The topsoil layer of A_c showed more degradation of pore structure than that of N_c, while pores of A_f topsoil did not show significant degradation compared with those of N_f. These results concluded that anthropogenic soils with coarse texture may have more effects on pore properties than ones with fine texture. The reestablished paddy fields may need more fundamental remediation to improve physical conditions.

• Clean Technology
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• v.22 no.2
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• pp.82-88
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• 2016

The loss of activity by coke is an important cause of catalyst deactivation during industrial operation. In this study, hydrogen ratio of reaction condition, which has influenced on coke formation over Pt-Sn catalyst, and regeneration of catalysts activity by coke burning, Pt sintering of coke burning as coke contents, effects of coke formation and deactivation with different Sn contents were confirmed. Pt-Sn-K catalyst supported on θ-alumina and γ-alumina was prepared progressively. Activity of regenerated catalyst for propane dehydrogenation was compared with fresh catalyst by coke burning, after propane dehydrogenation was carried out with different hydrogen ratio at 620 ℃ on fresh catalyst. Regenerated catalyst’s physical characterization such as BET, coke analysis and XRD was investigated. Through catalytic activity test and characterization, Sn contents of catalyst and hydrogen ratio in feed stream could affect coke formation on catalyst surface. Excessive coke makes loss of activity and Pt sintering during air regeneration process.

• Advances in concrete construction
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• v.17 no.2
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• pp.111-126
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• 2024

During the clinkering stages of cement production, the chemical composition of fine raw materials such as limestone and clay, which include iron oxide (Fe₂O₃), silicon dioxide (SiO₂) and aluminum oxide (Al₂O₃), significantly influences the quality of the final product. Specifically, the chemical interaction of Fe₂O₃ with CaO, SiO₂ and Al₂O₃ during clinkerisation plays a key role in determining the chemical reactivity and overall quality of the final cement, shaping the properties of the concrete produced. As an extension, this study aims to investigate the physical effects of incorporating nanosized Fe₂O₃ particles as fillers in concrete matrices, and their impact on concrete structures, namely slabs. To accurately model the reinforced concrete (RC) slabs, a refined trigonometric shear deformation theory (RTSDT) is used. Additionally, the stochastic Eshelby's homogenization approach is employed to determine the thermoelastic properties of nano-Fe₂O₃ infused concrete slabs. To ensure comprehensive coverage in the study, the RC slabs undergo various mechanical loads and are exposed to temperature fields to assess their thermo-mechanical performance. Furthermore, the slabs are assumed to rest on a three-parameter viscoelastic foundation, comprising the Winkler elastic springs, Pasternak shear layer and a damping parameter. The equilibrium governing equations of the system are derived using the principle of virtual work and subsequently solved using Navier's technique. The findings indicate that while ferric oxide nanoparticles enhance the mechanical properties of concrete against mechanical loading, they have less favorable effects on its performance against thermal exposure. However, the viscoelastic foundation contributes to mitigating these effects, improving the concrete's overall performance in both scenarios. These results highlight the trade-offs between mechanical and thermal performance when using Fe₂O₃ nanoparticles in concrete and underscore the importance of optimizing nanoparticle content and loading conditions to improve the structural performance of concrete structures.

• The Korean Journal of Pharmacology
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• v.19 no.2
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• pp.17-24
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• 1983

Buxus leaves(Buxus microphylla var. koreana Nakai) have been used as a folk medicine in treating woman's disease. The chemical constituents, which have teen identified from Buxus sempervirens L. in Europe, are so far known in isolation of buxus alkaloids, cyclobuxine, buxamine, norbuxamine and buxaminol. But But any study on the pharmacological action of Buxus microphylla var. koreana Nakai has not yet teen rallied out, however, active substances have not been identified. As an attempt to isolate the biologically active substances from this plant, the examination of chemical constituents was undertaken. In the experiment, the crystalline component$(C_{10}H_8O_4)$ obtained from Buxus microphylla var. koreana Nakai was identified as a 6-methoxy, 7-hydroxy coumarin by chemical and physical methods. We named this crystal buxuletin. Therefore, we intended to screen the pharmacological action of buxuletin, especially, its diuretic effects in rabbits. Buxuletin was intraveneously injected to the rabbit in the dose of 20 mg/kg, 10 mg/kg and 5 mg/kg. The variations of urine volume and minerals $(Na^+,\;K^+\;and\;Cl^-)$ in urine were measured at an interval of 15 minutes for 4 hours after the treatment of buxuletin. The observed results are as follows: 1) With the administration of buxuletin (20 mg/kg, 10 mg/kg), the remarkable increment of the excreted urine volume was observed during the relatively long period. Excretion rates of urinary minerals $(Na^+,\;K^+\;and\;Cl^-)$ were also increased. 2) In a dose of 5 mg/kg, the slight increment on the diuretic actions of rabbits was observed. From the above results, authors name this crystal buxuletin and buxuletin shows the diuretic action.

• Journal of the Korean Society for Marine Environment & Energy
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• v.12 no.1
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• pp.55-59
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• 2009

As one of the methods for recycling the FRP from the small and medium waste ships, separation of roving layer from the mat has some merits in a sense of the recycling energy and the environmental effects. Similar characteristics, however, between the roving and the mat even with different ratio of the resin and the glass and the thickness of the roving, much thinner than the mat, make the mechanically automatic differentiation difficult. In this study spectrochemical differentiation between the two layers has been made using (1) boiling concentrated sulfuric acid which can dissolve the resin in the FRP layer, (2) methanol and isopropanol solution saturated with KOH which can dissolve the glass, or (3) hydrogen fluoride(HF) solution which can reacts with $SiO_2$ fragments of the glass. Furthermore coloring water-soluble dye following the HF treatment makes the roving layer more distinguishable photo-physically.

• Polymer(Korea)
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• v.35 no.5
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• pp.385-389
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• 2011

In rubbing process, process factors, the properties of alignment layer and the physical properties of rubbing cloth have acted as important variables. These factors affect the orientation properties of the alignment layer by rubbed extent that is determined by rubbing density and rubbing force. In this work, we studied the effects of rubbing cloths with different pile density and rigidity on rubbing density(length) and rubbing force. As the pile density and rigidity of rubbing cloths increased, the birefringence and the surface roughness of the rubbed alignment layers became bigger, but the characteristics of rubbing-effect had differed each other. The pile density of rubbing cloths which was related with the number of pile, affected the rubbing density(length). On the other hand, the pile rigidity of rubbing was closely related to rubbing force rather than the rubbing density(length).

• Polymer(Korea)
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• v.38 no.2
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• pp.225-231
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• 2014

The rheological properties of highly concentrated polymer bonded explosive simulant were studied by using poly(ethylene-co-vinyl acetate) with 30 and 60% vinyl acetate (VA) content as a binder, respectively. Calcium carbonate and Dechlorane, whose physical properties are similar to resarch department explosive (RDX)'s, were used as fillers. The suspensions were mixed in a batch melt mixer and it was possible to fill 75 v% at maximum. From dynamic mechanical analysis, Dechlorane showed higher interaction with binder resins than that with calcium carbonate fillers. The effects of microstructural change on the rheological properties of the suspensions were investigated by a plate-plate rheometer with constant shear rate and constant shear stress modes, respectively. The theoretical maximum packing fraction of EVA31/Dechlorane suspension obtained from Krieger-Dougherty equation was 70 v% and it was thought that 2000 Pa was proper shear stress condition for this melt processing.

• Applied Chemistry for Engineering
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• v.17 no.3
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• pp.274-279
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• 2006

To synthesize ZnO colloidal solution by a sol-gel process, zinc acetate ($C_{4}H_{6}O_{4}Zn{\cdot}2H_{2}O{\cdot}0.2\;mol$) and lithium hydroxide ($LiOH{\cdot}H_{2}O{\cdot}0.14\;mol$) in the ethanol were added to the solution containing a dispersing agent, hydroxypropyl cellulose (HPC). The nanosize and physical shape of the synthesized ZnO particles were determined by HPC acting as the dispersing agent. Nanosized ZnO particles were also obtained by a precipitation method based on zinc-2-ethylhexagonate. The precipitates were characterized by DLS, XRD, FE-SEM, and UV-vis. As the results, the ZnO colloids tend to self-assemble into a well-ordered hexagonal close-packed structure. The ZnO nanoparticles have an average diameter of nearly 40 nm with a narrow size distribution.