• Transactions of the Korean Society of Mechanical Engineers B
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• v.29 no.4 s.235
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• pp.453-459
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• 2005

In this paper, we are proposing a robust tool which is capable of measuring the size and elemental composition of submicron particles from twenty to several hundreds nanometers at the same time, i.e., named Single Particle Mass Spectrometer (SPMS). The home-made SPMS employs a laser ablation/multi-photon ionization method to tear a nanoparticle into the constituent elemental ions. One thing different from the conventional Aerosol Time-of-Flight Mass Spectrometer (ATOFMS) is the power of the ionization laser. Much strong laser used in this work makes it possible to generate elemental ions rather than molecular ions from a nanoparticle. Also the use of high power laser may guarantee a complete ionization of a particle, which was confirmed by the existence of multiple charged ions. If a particle is evaporated/ionized completely and detected through electric field-free TOF tube without any loss, we can extract the original particle volume from the measured total ion numbers. Collecting a number of particles mass spectra, we get a database of size and elemental composition of nanoparticles, with which we may take a took into any kinds of chemical reaction occurring at nanoscale. Several issues related to size estimation by SPMS will be discussed.

• The Korean Journal of Food And Nutrition
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• v.34 no.3
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• pp.295-301
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• 2021

Steaming is a method that has traditionally been used for medicinal plant extraction. This study investigated nitrite oxide production, ferrous ion chelating activity, α-glucosidase, xanthine oxidase, and acetylcholinesterase inhibitory activities of ethanol, acetone and hot-water extracts of Codonopsis lanceolata prepared by steaming seven times. MTT assay showed that each extract was non-toxic up to a concentration of 700 ㎍/mL confirming that there was no cytotoxicity in all extracts. The α-glucosidase, xanthine oxidase, and acetylcholinesterase inhibitory activities exhibited by the hot-water extract obtained from steaming seven times were higher (83.1%) than the other extracts. Higher production of nitrite oxide and better ferrous chelating activity was recorded with hot-water extract compared to ethanol and acetone extracts. These results indicated that more steaming of Codonopsis lanceolata extracts would be required to validate the possibility of developing antioxidants. Also, further study is needed to determine if the components present in the tested extracts might be useful in the prevention of Alzheimer's disease. These results showed that hot-water extracts may be useful for their antioxidant and the production inhibitory activity of nitrite oxide. It will be helpful in the investigation of the constituent analysis of the steam-processed product of Codonopsis lanceolata.

• Polymer(Korea)
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• v.24 no.6
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• pp.886-892
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• 2000

Poly(4-vinyl phenol) (PVPh) was neutralized by LiOH and PVPh ionomers (PVPh-Li) with different Li neutralization extents were synthesized. The variation in $T_{g}$ with Li neutralization was determined by DSC and the results show that the $T_{g}$ increases by 3.$8^{\circ}C$ per Li mol%. When comparing this result with the 3.$2^{\circ}C$ per Na mol% reported for poly (styrene-co-hydroxy styrene), the greater value for PVPh-Li may be due to a strong interaction between unneutralized free -OH and -OLi produced. No distinct small angle X-ray scattering (SAXS) peak was observed for these PVPh ionomers in bulk. In the 50/50 blend of PVPh-Li with PVPh, the miscibile blend was obtained when the Li neutralization in PVPh-Li was 10 mol%. On the contrary, the 50/50 PVPh-Li/PMMA was immiscible when the Li neutralization was 5 mol%. It can be concluded that, even if the starting blend is miscible owing to hydrogen bonding, the miscibility of blend becomes diminished by introducing small amount of ion groups into one of the constituent polymers and the blend can be immiscible as long as any new strong intermolecular ion-dipole interaction is not generated.

• Korean Journal of Soil Science and Fertilizer
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• v.28 no.2
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• pp.114-122
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• 1995

Complexation experiment between humic acid and heavy metal cations was conducted to clear information on heavy metal adsorption by soil organic constituent. The absorbance of UV-visible light of humic acid-metal complexes increased with increasing wavelength, and the order of their absorbance was in the order of Zn->Cd->Cu- saturated humic acid. Carboxyl and phenolic OH groups participated in the complex formation between heavy metal cations and functional groups of humic acid, and the amounts complex was in the order of $Cu^{+{+}}$ > $Zn^{+{+}}$ $\geq$ $Cd^{+{+}}$. The stability constants of humic acid-metal complexes increased with increasing pH, and the order of first stability constants was $Zn^{+{+}}$ > $Cd^{+{+}}$ > $Cu^{+{+}}$, and those of second and overall stability constants were $Cu^{+{+}}$ > $Zn^{+{+}}$ > $Cd^{+{+}}$. With increasing pH, the average binding numbers betwen heavy metal cations and functional groups of humic acid increased the order of $Cu^{+{+}}$ > $Zn^{+{+}}$ > $Cd^{+{+}}$. It was postulated that two types of complexations between heavy metal cations and functional groups of humic acid. One was the reactions in which only carboxyl groups participated to form complexes, and the other was those in which both carboxyl and phenolic OH groups simultaneously participated.

• Proceedings of the Korean Vacuum Society Conference
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• 2012.08a
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• pp.231-231
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• 2012

Correct determination of the interface locations is critical for the calibration of the depth scale and measurement of layer thickness in SIMS depth profiling analysis of multilayer films. However, the interface locations are difficult to determine due to the unwanted distortion from the real ones by the several effects due to sputtering with energetic ions. In this study, the layer thicknesses of Si/Ge and Si/Ti multilayer films were measured by SIMS depth profiling analysis using the oxygen and cesium primary ion beam. The interface locations in the multilayer films could be determined by two methods. The interfaces can be determined by the 50 at% definition where the atomic fractions of the constituent layer elements drop or rise to 50 at% at the interfaces. In this method, the raw depth profiles were converted to compositional depth profiles through the two-step conversion process using the alloy reference relative sensitivity factors (AR-RSF) determined by the alloy reference films with well-known compositions determined by Rutherford backscattering spectroscopy (RBS). The interface locations of the Si/Ge and Si/Ti multilayer films were also determined from the intensities of the interfacial composited ions (SiGe+, SiTi+). The determination of the interface locations from the composited ions was found to be difficult to apply due to the small intensity and the unclear variation at the interfaces.

• Korean Journal of Environmental Biology
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• v.29 no.4
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• pp.305-311
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• 2011

The distribution of flocculating activity of culture broth was examined and the major constituent with flocculating activity was identified. Most of flocculating activity was found in culture broth without cells. As the activity was maintained by the digestion with pronase, it suggests that the activity is due to the polysaccharide. The bioflocculant obtained from $Lactobacillus$ $jensenii$ YW-33 was precipitated by 60~80% EtOH fractionation (LJ-80). LJ-80 was separated by ion-exchange chromatography using DEAE-Toyopearl 650C and LJ-80-II showed more potent flocculating activity than those of other fractions. The major activity fraction LJ-80-II was further purified on the gel permeation using Sepharose CL-6B to LJ-80-II-1. GPC (Sepharose CL-6B) and HPLC were used to determine whether LJ-80-II-1 has a homogenecity. The molecular weight of purified LJ-80-II-1 was estimated over 800,000 dalton by gel permeation chromatography. Purified LJ-80-II-1 contained 98.4% total sugar, 0.6% protein. Main sugar of purified LJ-80-II-1 was composed of mannose : galactose : glucose with a molar ratio of 1.61 : 0.25 : 1.00.

• Korean Journal of Soil Science and Fertilizer
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• v.16 no.1
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• pp.36-41
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• 1983

These studies were carried out to investigate the effects of potassium salts on the changes of chemical properties in submerged soil. Rice plants were cultured in submerged soil using potassium salts. Obtained results were as follows. In the submerged soil cultured with rice plants the value of pH was higher in the potassium chloride plot than in the potassium sulfate plot. The leaching of cations such as calcium, magnesium, potassium and ammonium were higher in the potassium chloride plot than in the potassium sulfate plot. On the other hand, the leaching of phosphate ion was slightly higher in the potassium sulfate plot than in the potassium chloride plot. The leaching of iron was higher in the planted plot than in the non-planted plot, but that of silica was higher in the non-planted plot than in the planted plot. However, the leaching of iron and silica was not affected by potassium salts.

• Economic and Environmental Geology
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• v.29 no.4
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• pp.483-493
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• 1996

The tectonic environment and source characteristics of the Daebo granitic batholith in the central Ogcheon Belt were investigated based upon major and trace element geochemistry. The batholith is comprised of three granite types; a biotite granite (DBBG), K-feldspar megacryst-bearing biotite granite (DBKG), and a more mafic granodiorite (DBGD). The variations of Na and K in the granites can not be explained by simple fractional crystallization from the same primary magma. The irregular behavior of these alkali elements indicates a variety of source materials or incomplete mixing of different source materials. The large ion lithophile (LIL) element enrichment and low Ta/Hf ratios of the granites are typical characteristics of normal, calc-alkaline continental arc granitoids. Based upon REE patterns of the granites, it seems to be unreasonable to regard the felsic DBBG as a late stage differentiate formed by residual melts after the fractionation of major constituent minerals of the more mafic DBGD. Inconsistent variations in ${\varepsilon}_{Nd}(t)$ and LIL element concentrations of the granites preclude a mixing model between primitive melt and LIL element-enriched upper crustal materials. The irregular geochemical variation of the granites is taken to be largely inherited from an already heterogeneous source region.

• Korean Journal of Microbiology
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• v.6 no.2
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• pp.63-67
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• 1968

Total carbohydrates, amino acids and peptide-like substances in two kinds of Korean lager beers have been analyzed by the calorimetric method of Dreywood's anthrone reagent and Fowden's ninhydrin reagent. The samples were fractionated with column of ion-exchange resin. The experimental results are as follows; 1. Amounts of non-hydrolyzed carbohydrates in the part of column processed is 1. 82% and 1. 96 % (the value was measured by Bertrand's method). But the amounts of those measured by Dreywood's anthrone method are 5.57% and 4.25%, this values are much more than those of Bertrand's method. 2. It can be estimated the amounts of gum and dextrin are 3.75% and 3.30% in both two beers, by comparison of samples with the above mentioned two method. 3. The amounts of carbohydrates by anthrone reagent in acid-hydrolyzed beers are much increased than those of non-hydrolyzed, so it is suggested the presence of polymer carbohydrates which couldn't be detected by Bertrand's method. 4. Total amounts of amino acids are 0.015% and 0.025% (as glycine) in non-hydrolyzed beers measured by ninhydrine color reaction method, on the other hand the amount of amino acids in acid hydrolyzed beers are 0.06% and 0.056%, this is much more than those of nonhydrolysis. The different amounts means that of peptide-like substances. 5. It is necessary to determine the constituent of amino acid for the better taste of beer, and also it is desirable to check the role of carbohydrates in the course of fermentation, mashing and on lager beer for effective utilization of carbohydrate materials to eliminate the losses.

• Korean Journal of Materials Research
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• v.15 no.7
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• pp.453-457
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• 2005

Piezoelectric properties of $Pb(Mn_{1/3}Nb_{2/3})O_3-PbZrO_3-PbTiO_3$ ceramics were investigated with $Al_2O_3$ content $(0.0-1.0 wt\%)$. The constituent phases, microstructure, electromechanical coupling factor, dielectric constant, piezoelectric charge and voltage constants were analyzed. Diffraction peaks for (002) and (200) planes were identified by X-ray diffractometer for all the specimens doped with $Al_2O_3$, indicating the MPB (morphotropic phase boundary) composition of tetragonal structures. The highest sintered density of $7.8 g/cm^3$ was obtained for $0.2wt\%\;Al_2O_3-doped$ specimen. Grain size increased by doping $Al_2O_3$ up to $0.3 wt\%$, and it decreased by more doping. Electromechanical coupling factor, dielectric constant, piezoelectric charge and voltage constants increased by doping $Al_2O_3$ up to $0.2wt\%$, and it decreased by more doping. This might result from the formation of oxygen vacancies due to defects in $O^{2-}$ ion sites and the substitution of $Al^{3+}$ ions.