• Proceedings of the Korean Radioactive Waste Society Conference
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• 2016.05a
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• pp.167-168
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• 2016

• Bulletin of the Korean Chemical Society
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• v.26 no.11
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• pp.1776-1782
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• 2005

ZnSe/ZnS, UV-blue luminescent core shell quantum dots, were synthesized via a thermal decomposition reaction of organometallic zinc and solvent coordinated Selenium (TOPSe) in a hot solvent mixture. The synthetic conditions of the core (ZnSe) and the shell (ZnS) were independently studied at various reaction temperature conditions. The obtained colloidal nanocrystals at corresponding temperatures were characterized for their optical properties by UV-vis, room temperature solution photoluminescence (PL) spectroscopy, and further obtained powders were characterized by XRD, TEM, and EDXS analyses. The synthetic temperature condition to obtain the best PL emission intensity for the ZnSe core was 300 ${^{\circ}C}$, and for the optimum shell capping, the temperature was 135 ${^{\circ}C}$. At this temperature, solution PL spectrum showed a narrow emission peak at 427 nm with a PL efficiency of 15%. In addition, the measured particle sizes for the ZnSe/ZnS nanocomposite via TEM were in the range of 5 to 12 nm. Furthermore, we have synthesized water-soluble ZnSe/ZnS nanoparticles by capping the ZnSe/ZnS hydrophobic surface with mercaptoacetate (MAA) molecules. For the obtained aqueous colloidal solution, the UV-vis spectrum showed an absorption peak at 250 nm, and the solution PL emission spectrum showed a peak at 425 nm, which is similar to that for hydrophobic quantum dot ZnSe/ZnS. However, the calculated PL efficiency was relatively low (0.1%) due to the luminescence quenching by water and MAA molecules. The capping ligand was also characterized by FT-IR spectroscopy, with the carbonyl stretching peak in the mercaptoacetate molecule appearing at 1575 $cm ^{-1}$. Finally, the particle sizes of the MAA capped ZnSe/ZnS were measured by TEM, showing a range of 12 to 17 nm.

• Journal of the Mineralogical Society of Korea
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• v.11 no.2
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• pp.117-125
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• 1998

Crystallization behavior of platinum minerals within Pt-Sb-Bi bearing ore magmas and mineralogical properties of the existing minerals were investigated at 1,00$0^{\circ}C$ by synthetic experiment. High purity reagents were used as starting materials and silica tubings as containers. Reaction products were analysed by reflecting microscopy, X-ray diffraction, electron probe microanalysis, and micro-hardness test. Stable minerals at 1,00$0^{\circ}C$ are platinum, electron probe microanalysis, and micro-hardness test. Stable minerals at $1,000^{\circ}C$ are platinum, stump-flite (PtSb) and geversite (PtSb2). They are in equilibrium with liquid (ore magma). Platinum contains considerable amount of Sb of 7.5 at.%, whereas Bi only up to 0.9 at.%. Pure stumpflite is hexagonal with space group P63/mmc, and unit cell parameters are a=4.1318(6), c=5.483(1)$\AA$. VHN50=417(2)$\AA$. Geversite has cubic structure with space group Pa3. Cell parameters are a=6.4373(2)$\AA$ and Vicker hardness values VHN50=663.5 (566~766). Both stumpflite and geversite show solid solution and their end-members are Pt48.8Sb40.7-Bi10.5, and Pt33.7-Sb59.8Bi6.5, respectively. Although stumpflite (m.p. $1,043^{\circ}C$) and unnamed PtBi (m.p. 7$65^{\circ}C$) do not form a complete solid solution at $1,000^{\circ}C$, they are known, at $600^{\circ}C$, to form a continuous solid solution. Geversit (m.p. $1,226^{\circ}C$) also forms complete solid solution with insizwaite (m.p. $660^{\circ}C$). Unit cell dimensions of the minerals above increases with the amount of Bi substituting for Sb.

• Journal of Life Science
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• v.11 no.4
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• pp.335-339
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• 2001

Cancer chemoprevention refers to the use of natural or synthetic substances to prevent initiational and promotional events that occur during the process of carcinogenesis. Thesium Chinese Turczaninow aqua-acupuncture solution (TCTAS) and Astragli Radix aqua-acupuncture solution (ARAS) were tested as the cancer chemopreventive agents using biochemical markers of carcinogenesis. The effects on the inhibition of phorbol 12- myristate 13-acetate(TPA)-induced free radical formation in HL-60 cells and the inhibition of polyamine metabolism were measured. There is significant inhibition of TAP-induced free radical formation in human leukemic cells with cells with ARAS. Proliferation of Acanthamoeba castellanii was inhibited by TCTAS and ARAS. TCTAS and ARAS positive in these assays may inhibit the carcinogenesis process and is considered promising cancer-preventing agents.

• Journal of the Korean Ceramic Society
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• v.22 no.1
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• pp.35-39
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• 1985

Synthetic mica $NaMg_{2.5}(Si_4O_{10})F_2 (Na-TSM)$ was treated with HCl solution and H-type exchange resin to investigate the chemical stability and the ion exchange by measuring the dissolution of chemical components and the exchanged $H^+$ ion. The replacement of $Na^+$ ion occurred in contact with HCl solution and H-type ion exchange resin at the surface of Na-TSM particles reached $Na^+$ ions at maximum value of 70~80%. $Mg^{2+}$ ion of octahedral layer became to dissolve from the pH2 solution and th amount of it dissolved in-creased almost proportional to $H^+$ ion concentration from around 0.02N $H^+$ ion equilibrium concentration. The crystalline structure of Na-TSM was destructed by dissolution of Mg2+ ion in cncentrated hydrochloric acid solution and resulted silica gel precipitation.

• Journal of Korea Technical Association of The Pulp and Paper Industry
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• v.43 no.5
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• pp.1-10
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• 2011

In this study, 13 water soluble polymers(6 natural polymer, 7 synthetic polymer) were treated on Hanji. Mechanical properties, morphology and oxidation index with thermal aging were measured on the aged Hanji, dewaxed Hanji and polymer treated Hanji. 3 natural polymer(such as CMC, EC, MC) and 3 synthetic polymers(such as PVA 1500, 2000, PEG 1500) treated Hanji had higher strength than other polymer treated Hanji. The oxidation index of 3% methyl cellulose solution treated Hanji did a little increase with thermal aging. Finally, methyl cellulose was found to be the most efficient method for strengthening the dewaxed Hanji. The best aging safety and thermal stability were obtained at the methyl cellulose 3% water solution.

• Journal of Positioning, Navigation, and Timing
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• v.8 no.4
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• pp.175-181
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• 2019

This paper suggests a velocity integration algorithm for Synthetic Aperture Radar (SAR) motion measurement to reduce discontinuity of range error. When using position data from Embedded GPS/INS (EGI) to form SAR image, the discontinuity of the data degrades SAR image quality. In this paper, to reduce the discontinuity of EGI position data, EGI velocity integration is suggested which obtains navigation solution by integrating velocity data from EGI. Simulation shows that the method improves SAR image quality by reducing the discontinuity of range error. INS is a similar algorithm to EGI velocity integration in the way that it also obtains navigation solution by integrating velocity measured by IMU. Comparing INS and EGI velocity integration according to grades of IMU and GPS, EGI velocity integration is more suitable for the real system. Through this, EGI velocity integration is suggested, which improves SAR image quality more than existing algorithms.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2002.11b
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• pp.52-52
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• 2002

Chitosan is a key compound of shrimp waste. It is a biopolymer, which is widely used in the field of medical Sciences. Chitosan-TPP (Tripolyphosphate) complex has more or less similar physical properties as Ca-alginate which can be used for the production of synthetic seeds. Possibility of the use of Chitosan-TPP complex as a matrix for encapsulation of somatic embryos was tested against the Ca-alginate complex (2.5w/v Na-alginate, 100mM CaCl2 at pH 5.5). Somatic embryos grown in the induction medium (IM) were drawn into the viscous chitosan solution (1%) and mixed well by inverting the tube carefully. Then the mixture was dropped at regular intervals into the tripolyphosphate (TPP) solution kept on a magnetic stirrer for bead formation. Synthetic seeds formed were washed and transferred into the incubation medium, then allowed either to air-dry or freeze-dry.(중략)

• Korean Journal of Environmental Agriculture
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• v.11 no.2
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• pp.125-132
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• 1992

This study was conducted to know degradation products of the synthetic pyrethroid insecticide bifenthrin under soil, aqueous solution and UV-light irradation, and know its movement by leaching in soil. The major degradation product of bifenthrin was identified with 2-methylbiphenyl -3-y1 methanol by HPLC, UV, Mass and NMR under soil, aqueous solution and UV-light irradiation, The main degradation route was hydrolysis of the ester linkage. On exposure to UV-light, bifenthrin was decomposed almost completely in concentrations of 10 and 100 ppm in 24 hr but decomposed about 80% in 1,000 ppm. Bifenthrin was immobile in soil column system and on soil thin-layer chromatography system. Mostly bifenthrin remained in the 0-2.0㎝ layer of soil column and soil TLC.

• Journal of Korean Society of Water and Wastewater
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• v.18 no.2
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• pp.174-180
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• 2004

This study is a fundamental research to test the applicability of abandoned eggshell as seed material for crystallization reaction. Eggshell was calcinated at $850^{\circ}C$ and ground to lesser than 0.42mm. The calcination characteristics of eggshell were examined by X-ray diffraction (XRD). The effect of initial calcium concentration, alkalinity, reaction temperature condition, seed dosage were studied by batch test. For the low concentration sample(P concentration is under 50mg/L), more than 90% of P can be removed. The effect of initial calcium concentration(0~120mg/L) was performed. At the result of the test, more than 50mg/L calcium concentration has high removal efficiency. Alkalinity effect was studied for synthetic solution(100mg/L initial P, 50mg/L calcium, 0.025% seed dosage) with 0~300mg/L bicarbonate alkalinities. For synthetic solution(100mg/L initial P, 50mg/L calcium, 100mg/L bicarbonate alkalinity, 0.025% seed dosage), the phosphorus concentration was examined with $10{\sim}35^{\circ}C$. In addition, calcinated eggshell was injected to swine wastewater to test the applicability to actual wastewater.