• Journal of the Korean Ceramic Society
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• v.47 no.6
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• pp.598-602
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• 2010

When metal oxides are added into crystalline glaze, colors of glaze and crystals are similar as colorants generally. But the case of NiO in zinc crystalline glaze is different from general color development. When NiO is added to zinc crystalline glaze it can develop two or three colors. The active use of color development mechanism by adding NiO to the zinc crystalline glaze to control color of the base glaze and crystal with stability is investigated. This report is expected to contribute to the ceramic industry in improving application of zinc crystalline glaze. For the experiment of NiO, the quantity of NiO additives is changed to the base glaze for the most adequate formation of willemite crystal from previous research and firing condition: temperature increasing speed $5^{\circ}C/min$, holding 1 h at $1270^{\circ}C$, annealing speed $3^{\circ}C/min$ till $1170^{\circ}C$, holding 2 h at $1170^{\circ}C$ then naturally annealed. The samples are characterized by X-ray diffraction (XRD), UV-vis, and Micro-Raman. The result of the procedure as follows; Ni substitutes for Zn ion then glaze develops blue willemite crystals, as if cobalt is used, on brown glaze base. When NiO quantity is increased to over 5 wt%, willemite size is decreased, and the density of the crystal is increased, at the same time $Ni_2SiO_4$ (olivine) phase, the second phase, has been developed. The excessive NiO is reacted with silicate in the glass then developed green $Ni_2SiO_4$ (olivine), and quantity of $Ni_2SiO_4$ (olivine) is increased as quantity of willemite is decreased. It is proved to create three colors, blue, brown and green by controlling the quantity of NiO to the zinc crystalline glaze and it will improve the multiple use of colors to the ceramic design.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.46 no.2
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• pp.46-52
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• 2009

In this paper, the timing estimator based on the principle of the best linear unbiased estimator (BLUE) is proposed in OFDMA uplink systems. The proposed timing estimator exploits the phase information of the differential correlation between adjacent subcarriers. The differential correlation can extract the information about timing offset and mitigate the distortion of the signal caused by the frequency selectivity of channel. Compared with conventional methods, the proposed estimator shows more accurate capability in estimation. In addition, the estimator is hardly affected by the distortion caused by the frequency selectivity of channel. Simulation results confirm that the proposed estimator shows a small error mean and a relatively small error variance. In addition, the performance of the estimator is evaluated by means of SNR loss. It is shown by simulations that the SNR loss of the proposed estimator by estimation errors is less than 0.4 dB for the SNR values between 0 and 20 dB. This might indicate that the proposed estimator is suitable for the timing synchronization of multiple users in OFDMA uplink systems.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2002.07a
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• pp.210-213
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• 2002

The blue phosphor, $BaMgAl_{10}O_{17}$:$Eu^{2+}$, showing a blue emission band at about 450 nm were prepared by solid state reaction of BaC $O_3$, A $l_2$ $O_3$, MgO and E $u_2$ $O_3$ with Al $F_3$ as a flux. The thermal quenching of BaMgAl $O_{17}$:E $u^{2+}$ phosphor significantly reduces the intensity of the blue emission. It is reduced by an amount of 50% after heating at around 800$^{\circ}C$ for 1 hr. The red emission in the 580∼720 nm region of $^{5}$ $D_{0}$\longrightarro $w^{7}$ $F_1$ and $^{5}$ $D_{0}$\longrightarro $w^{7}$ $F_2$ transition of $Eu^{3+}$ is produced from the phosphor heated above 1,100$^{\circ}C$. The EPR spectrum also reveals that some part of E $u^{2+}$ ions are oxidized to trivalent ions above 1,100$^{\circ}C$ at around 90 and 140mT. This oxidation evidence is also detected from XANES absorption spectra for $L_{III}$ shell of Eu ions: an absorption peak is at 6,977eV of E $u^{2+}$ and 6,984eV of $Eu^{3+}$. The combined X-ray and neutron data suggests that the new phase of EuMgA $l_{11}$ $O_{19}$ magnetoplumbite structure may be formed by heat treatment.eat treatment.tment.eat treatment.tment.t.

• Journal of the Korean Ceramic Society
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• v.51 no.3
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• pp.184-189
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• 2014

Electric arc furnace dust (EAFD) is a solid waste generated by the steel-scrap recycling process. It mainly consists of zinc oxides (ZnO), alumina ($Al_2O_3$), iron oxides ($Fe_2O_3$), and silica ($SiO_2$). Here we report the preparation and characterization of blue ceramic pigments using EAFD powder as a starting material. $(Zn(EAFD),Co)Al_2O_4$ blue ceramic pigment was prepared by the solid-state reaction method. The color characteristics of the pigment obtained were compared with those of pure $CoAl_2O_4$. The new pigment was characterized using XRD, CIE-$L^*a^*b^*$ color-measurements, SEM, and EDX. The XRD analysis revealed that the $(Zn(EAFD),Co)Al_2O_4$ pigment was composed of mainly the spinel phase of $(Zn,Co)Al_2O_4$. The $Zn(EAFD)_{0.25}Co_{0.75}Al_2O_4$ pigments showed a vivid blue color with a $b^*$ value of -28.64 and a good glaze stability with a transparent glaze.

• Korean Chemical Engineering Research
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• v.43 no.3
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• pp.360-365
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• 2005

SMB (simulated moving bed) is a continuous chromatographic process by shifting periodically port position. Binary of mixture, Blue dextran and Orange G, was separated by SMB. These components have unique color individually, that is, Blue dextran is blue and Orange G is orange. It is easy to understand SMB process by observing the shift of color changes in SMB. These components was not adsorbed to stationary phase and isolated by difference of size exclusion factor. Mass transfer coefficient was determined by single pulse test under several flow rate conditions. Operation condition was obtained by standing wave theory and optimized for high purities in extract and raffinate streams. Experiment was performed in open loop 4 zone (2-2-2-2) SMB. There are several advantages in open loop SMB, where extract is product for high purity. It is also easy to control flow rate and monitor experimental state during operation. Experimental, extract and raffinate history is well fitted with simulation results, however, column concentration profile is a little different from simulation results. Purities were 99.5％ for extract and 98.9％ for raffinate and extract and raffinate yields were obtained as 98.9％ and 99.4％ respectively.

• Applied Chemistry for Engineering
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• v.23 no.2
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• pp.148-152
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• 2012

Anatase and anatase/rutile $TiO_2$ samples were prepared at $HNO_3$/TTIP molar ratio of 0.1, 0.5, 1.0, and 1.5 to study the effects of the physical properties of $TiO_2$ on photocatalytic decomposition of methylene blue. The physical properties of the samples were measured with XRD, SEM, TEM, BET, FT-IR, and UV-vis spectroscopy. Anatase phase was observed at $HNO_3$/TTIP of 0.1 and anatase/rutile phases were observed at $HNO_3$/TTIP of 0.5~1.5. Rutile crystal phase, mesopore size between $TiO_2$ nanoparticles, and surface OH group on $TiO_2$ sample were gradually increased with increasing the molar ratio of $HNO_3$/TTIP and the residual methylene blue concentration before UV irradiation decreased from 78.0 to 53.3%. After UV irradiation, the residual methylene blue concentrations of the samples prepared at $HNO_3$/TTIP of 0.1, 0.5, 1.0, and 1.5 were 20, 14, 11, and 23%, respectively, and the sample prepared at $HNO_3$/TTIP of 1.0 showed the best photocatalytic ability.

• Korean Journal of Veterinary Research
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• v.27 no.2
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• pp.347-359
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• 1987

To investigate the changes of pituitary gland associated with ovarian cyst in Korean native cattle, pituitaries and ovaries were collected from 54 Korean native cattle at abbatoir. Pituitaries were stained with HerIant pituitary stain method and all the tissues were examined under light microscope. The results obtained were summarized as follows; 1. The delta cells and beta cells in the pars distalis were dull blue and violet in colors respeetively. Basophil size in the follicular phase and pregnant groups was larger than those of luteal phase and ovarian dysfunction groups. 2. The numbers of delta cells in the pars distalis of follicular cyst group were larger than those of remaining groups (p<0.01). 3. The distribution of delta cells in the acidophil zone was greater than that in the basophil zone of the follicular cyst and follicular phase groups. 4. The granulations of delta cells were more intensive in follicular cyst, follicular phase and pregnancy groups than in luteal phase and ovarian dysfunction groups (p<0.01). 5. The numbers of beta cells in follicular phase and ovarian dysfunction groups were larger than those in luteal phase and follicular cyst groups respectively (p<0.01). 6. In all groups, the distribution of beta cells was greater in basophilic zone than in acidophilic zone (p<0.01).

• Microbiology and Biotechnology Letters
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• v.44 no.1
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• pp.89-97
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• 2016

Obesity is caused by excess accumulation of body fat and contributes to various pathological disorders such as diabetes, hypertension, cardiovascular disease, and cancer. In this study, we investigated the effect of a 30% ethanol extract of Fructus Rosae laevigata (RLE) on adipogenesis in 3T3-L1 adipocytes, measured by triglyceride accumulation and expression of adipogenesis-related transcription factors during differentiation of pre-adipocytes into adipocytes. RLE decreased the intracellular triglyceride contents (assessed by Oil Red-O staining) in a dose-dependent manner. It also downregulated the expression of adipogenic transcription factors and inhibited cell proliferation during the mitotic clonal expansion phase of adipocyte differentiation by inducing G1 phase arrest. We investigated the alterations in the levels of G1 phase arrest-related proteins. The expression of p21 protein significantly increased, while the levels of Cyclin E, Cdk2, and phospho-Rb decreased in a dose-dependent manner in 3T3-L1 cells treated with RLE. These results suggest that RLE inhibits the differentiation of 3T3-L1 adipocytes by suppressing the expression of adipogenic transcription factors and inducing G1 phase arrest in the early stages of adipocyte differentiation.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.19 no.5
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• pp.268-276
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• 2009

In this study, activated carbon (AC) was treated with ferric ion by a sol-gel method. The compound (Fe-AC) was employed for the preparation of Fe-activated carbon/$TiO_2$, (Fe-AC/$TiO_2$) composites. The prepared Fe-AC/$TiO_2$ composites were characterized with surface properties, structural crystallinity, elemental identification and photocatalytic activity. The SEM results showed that ferric compounds and titanium dioxide were fixed onto the AC surfaces. The XRD results showed that Fe-AC/$TiO_2$ composites mostly contained anatase phase. EDX showed the presence of C, O, and Ti with Fe peaks in all samples. Its photocatalytic degradation effect was evaluated with the degradation behavior of the methylene blue (MB) solution. MB degradation could be attributed to the synergetic effects of adsorption, photo-degradation of $TiO_2$ and photo-Fenton of Fe component. The degradation rate for this photocatalysis was evaluated as a function of the concentration of the dye, the amount of $TiO_2$ and the pH. Photocataytic activity is good at activity pH.

• Applied Chemistry for Engineering
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• v.20 no.5
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• pp.565-569
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• 2009

Nano-sized green and blue phosphor powders were synthesized by liquid phase method to confirm the size and morphology. By using that process, the particle sizes of green and blue phosphor particles were 80 nm and 60 nm, respectively. The characteristic comparison of $Zn_2SiO_4$ : Mn and BAM : Eu was carried out and as a result, $Zn_2SiO_4$ : Mn powders showed an higher PL performance compared to BAM : Eu.