• Proceedings of the PSK Conference
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• 2003.10b
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• pp.231.3-232
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• 2003

The biomedical applications of chitosan have been widely researched. FN mediates its biological effects through binding to the hetero-dimeric transmembrane glycoproteins, integrins, which physically couple the cytoskeleton to the ECM. FN binds to the integrin through a consensus site including the Arg-Gly-Asp (RGD) sequence within tenth type III module (Ruoslahti & Pierschbacher 1987). A short sequence Pro-His-Ser-Arg-Asn (PHSRN) has also been identified as a synergistic motif within ninth type III module for binding to ${\alpha}$5${\beta}$1 integrin (Aota et al. 1994). (omitted)

• Journal of Life Science
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• v.34 no.3
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• pp.160-169
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• 2024

In this study, Abies nephrolepis MAX. was divided into A. nephrolepis MAX. stem (AS) extract and A. nephrolepis MAX. leaf (AL) extract. Their anti-inflammatory abilities and applicability as cosmetic materials were determined. Tests of the cell survival rate measured using RAW 264.7 cells and extracts of AS and AL showed 97.8% and 95.6% cell viability at a 500 ㎍/ml concentration. To determine anti-inflammatory activity, we examined the inhibitory effects on the production of LPS-induced NO in RAW 264.7 cells by Griess assay. The results showed that the AS and AL extracts presented a concentration-dependent inhibition of NO production. The protein expression inhibitory effects of AS and AL extracts were measured by western blot at 25, 50, and 100 ㎍/ml concentrations. β-actin was used as a positive control. The results of western blot of extracts from AS showed that the expression inhibition rate of the iNOS protein was decreased by 50.1% at the 100 ㎍/ml concentration. Additionally, the results of western blot of AL extracts showed that the expression inhibition rate of COX-2 and iNOS protein was decreased by 66% and 8.2% at the 100 ㎍/ml concentration. The mRNA inhibitory effect was measured by RT-PCR at 25, 50, and 100 ㎍/ml concentrations. GAPDH was used as a positive control. Consequently, the iNOS mRNA expression effect by RT-PCR of AS extract demonstrated by RT-PCR decreased by 27.9% at the 100 ㎍/ml concentration, and the iNOS and IL-6 mRNA expression effect of AL extract measured by RT-PCR decreased by 48.6% and 48.7% at the 100 ㎍/ml concentration.

• Journal of the Korean Institute of Gas
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• v.10 no.1 s.30
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• pp.38-42
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• 2006

In this study, a simulation technology for refrigeration cycle which can liquefy and store liquified petroleum gas (LPG) using pure propane as a refrigerant has been introduced. Cooling water as the second cooling medium was used for the liquefaction of propane. Peng-Robinson equation of state was used for the entire refrigeration cycle. A new alpha formulation proposed by Twu et al. was used for the more accurate prediction of vapor pressures of pure propane component and LPG constituents. API method for the accurate estimation of liquid densities of propane and LPG was used instead of using Peng-Robinson equation of state. PRO/II with PROVISION release 7.1, a general purpose chemical process simulator was used for the simulation of the overall refrigeration system. Through this work, we can successfully simulate the real propane refrigeration plant operating at domestic site.

• Proceedings of the Korean Society of Crop Science Conference
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• 2017.06a
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• pp.235-235
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• 2017

Chromium (Cr) toxicity is hazardous to the seed germination, growth, and development of plants. ${\gamma}$-Aminobutyric acid (GABA) is a non-protein amino acid and is involved in stress tolerance in plants. To investigate the effects of GABA in alleviating Cr toxicity, we treated eight-d-old mustard (Brassica juncea L.) seedlings with Cr (0.15 mM and 0.3 mM $K_2CrO_4$, 5 days) alone and in combination with GABA ($125{\mu}M$) in a semi-hydroponic medium. The roots and shoots of the seedlings accumulated Cr in a dose-dependent manner, which led to an increase in oxidative damage [lipid peroxidation; hydrogen peroxide ($H_2O_2$) content; superoxide ($O{_2}^{{\cdot}-}$) generation; lipoxygenase (LOX) activity], MG content, and disrupted antioxidant defense and glyoxalase systems. Chromium stress also reduced growth, leaf relative water content (RWC), and chlorophyll (chl) content but increased phytochelatin (PC) and proline (Pro) content. Furthermore, supplementing the Cr-treated seedlings with GABA reduced Cr uptake and upregulated the non-enzymatic antioxidants (ascorbate, AsA; glutathione, GSH) and the activities of the enzymatic antioxidants including ascorbate peroxidase (APX), monodehydroascorbate reductase (MDHAR), dehydroascorbate reductase (DHAR), glutathione reductase (GR), glutathione peroxidase (GPX), superoxide dismutase (SOD), catalase (CAT), glyoxalase I (Gly I), and glyoxalase II (Gly II), and finally reduced oxidative damage. Adding GABA also increased leaf RWC and chl content, decreased Pro and PC content, and restored plant growth. These findings shed light on the effect of GABA in improving the physiological mechanisms of mustard seedlings in response to Cr stress.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.10 no.11
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• pp.3253-3259
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• 2009

In this study, a computer simulation has been performed for the refrigeration cycle using mixed refrigerants in order to decrease the process stream temperature to $-20^{\circ}C$. Refrigerant supply temperature was assumed to be $-30^{\circ}C$ considering the temperature difference as $10^{\circ}C$ with process stream. Peng-Robinson equation of state model was selected for the computer simulation. A new alpha function proposed by Twu et al was used for an accurate prediction of pure component vapor pressure experimental data. One fluid mixing rules were used for the estimation of mixture vapor-liquid equilibria calculations. A commercial process simulator, PRO/II with PROVISION was utilized for the simulation of the overall refrigeration process. In order to minimize the compressor power consumption, we have optimized the two-stage compression system by varying the first stage compressor outlet pressure. Finally, we could obtain the minimum total power 755.7kW at the first stage compressor outlet pressure, 6 bar.

• Journal of Korea Foundry Society
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• v.13 no.4
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• pp.369-381
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• 1993

Aluminum alloy(AC8A) matrix composites reinforced with SiC particles(10% in vol.) were fabricated by Centrifugal Spray Deposition(CSD) process. The microstructures were investigated in order to evaluate both the mixing mode between aluminum matrix and SiC particles, and the effect of SiC particles on the cooling behaviours of droplets during flight and preforms deposited. A non-continuum mathematical calculation was performed to explain and to quantify the evolution of microstructures in the droplets and preforms deposited. Conclusions obtained are as follows; 1. The powders produced by CSD process showed, in general, ligament type, and more than 60% of the powders produced were about 300 to 850 um in size. 2. AC8A droplets solidified during flight showed fine dendritic structure, but AC8A droplets mixed with SiC particles showed fine equiaxed grain structure, and eutectic silicon were formed to crystallize granularly between fine aluminum grains. 3. SiC particles seem to act as a nucleation sites for pro-eutectic silicon during solidification of AC8A alloy. 4. The microstructure of composite powders formed by CSD process showed particle embedded type, and resulted in dispersed type microstructure in preforms deposited. 5. The pro-eutectic silicon crystallized granularly between fine aluminum grains seem to prohibit grains from growth during spray deposition process. 6. The interfacial reactions between aluminum matrix and SiC particles were not observed from the deposit performs and the solidified droplets. 7. The continuum model seem to be useful in connecting the processing parameters with the resultant microstructures. From these results, it was concluded that the fabrication of aluminum matrix composites reinforced homogeneously with SiC particles was possible.

• Proceedings of the Plant Resources Society of Korea Conference
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• 2010.10a
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• pp.13-13
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• 2010

In the present study, the chemical constituents of Artemisia fukudo essential oil (AFE) were investigated using GC-MS. The major constituents were ${\alpha}$-thujone (40.28%), ${\beta}$-thujone (12.69%), camphor (6.95%) and caryophyllene (6.01%). We also examined the effects of AFE on the production of nitric oxide (NO), prostaglandin $E_2$ ($PGE_2$), tumor necrosis factor-${\alpha}$ (TNF-${\alpha}$), interleukin-IL-$1{\beta}$ (IL-$1{\beta}$), and IL-6 in lipopolysaccharide (LPS)-activated RAW 264.7 cells. Western blotting and RT-PCR analyses indicated that AFE has potent dose-dependent inhibitory effects on pro-inflammatory cytokines and mediators. We investigated the mechanism by which AFE inhibits NO and $PGE_2$ by examining the level of nuclear factor-${\kappa}B$ (NF-${\kappa}B$: p50 and p65) activation within the mitogen-activated protein kinase (MAPK: ERK, JNK and p38) pathway, which is an inflammation induced signal pathway in RAW 264.7 cells. AFE inhibited LPS-induced ERK, JNK and p38 phosphorylation. Furthermore, AFE inhibited the LPS-induced phosphorylation and degradation of $I{\kappa}B-{\alpha}$, which is required for the nuclear translocations of the p50 and p65 NF-${\kappa}B$ subunits in RAW 264.7 cells. Our results suggest that AFE might exert an anti-inflammatory effect by inhibiting the expression of pro-inflammatory cytokines. Such an effect is mediated by a blocking of NF-${\kappa}B$ activation which consequently inhibits the generation of inflammatory mediators in RAW 264.7 cells. AFE may be useful for treating inflammatory diseases.

• Restorative Dentistry and Endodontics
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• v.24 no.4
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• pp.628-632
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• 1999

Currently electronic apex locators have been widely used to determine working length in endodontic treatment. According to Manufacture's recommendation, it is beneficial to find the working length before instrumenting the canal. However, in crown-down pressureless technique, working length of tooth is established following coronal instrumentation 3mm short of radiographic apex. In narrow canals, mechanically formed constriction might be established by coronal instrumentation in some distance from anatomical constriction. The purpose of this study was to evaluate the accuracy of Root-ZX in the canal with mechanical constriction following considerable coronal enlargement with ProFile .06 series. The 40 root canals in 30 extracted mandibular molars were accessed, and their actual length (AL) established by passing a size 10 file just through the minor apical foramen. The teeth were then embedded in an acrylic container with normal saline. The initial canal length(IL) was measured with Root-ZX by negotiating a size 10 file to the apical constriction. The canal was sequentially enlarged to size 40 with ProFile .06 file 3mm short of actual length. The enlarged final canal lengths (FL) were obtained with a size 15 file. The average values of IL, FL were calculated and compared using Repeated measures Analysis of Variance followed Turkey's Studentized Range test. The results were obtained as follows: 1. The initial canal length was 0.12mm shorter than actual canal length(P>0.05). 2. The differences between initial canal length and final canal length were not significant(P>0.05). 3. As a result of this study, regardless of mechanically formed constriction. Root-ZX differentiated between mechanical and anatomic constriction.

• Journal of the Korean Crystal Growth and Crystal Technology
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• v.31 no.3
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• pp.116-126
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• 2021

Diesel particulate filter (DPF) is a typical application field of cordierite (Mg₂Al₄Si₅O₁₈) honeycomb. Green body for DPF honeycomb was extruded using slurry paste and sintered at the temperature range of 980~1450℃. Quantitative crystal phase analysis was carried out by using Rietveld refinement method for powder XRD data. In conjunction with the quantitative Rietveld analysis, SEM-EDS analysis was carried for the crystal phases (indialite, cordierite, cristobalite, alumina, spinel, mullite, pro-enstatite). After removing amorphous phase on the sintered surfaces by chemical etching method, the shape and composition of the crystal phases can be clearly identified by SEM-EDS method. By combining the Rietveld refinement method and SEM-EDS analysis, crystal phase evolution process in DPF cordierite ceramics could be clarified. In addition, the coefficient of thermal expansion (CTE) of the DPF honeycombs were measured and compared with the calculated CTEs based on the quantitative crystal phase analysis results.

• Analytical Science and Technology
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• v.21 no.1
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• pp.58-63
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• 2008

Nano-sized ZnO crystals were successfully incorporated using ion exchange method in TMA-A zeolite synthesized by the hydrothermal method. The optimal composition for the synthesis of TMA-A zeolite was resulted in a solution of $Al(i-pro)_3$ : 2.2 TEOS : 2.4 TMAOH : 0.3 NaOH : 200 $H_2O$. 0.3 g of TMA-A zeolite and 5 mol of $ZnCl_2$ solution were employed for the preparation of ZnO incorporated TMA-A zeolite. The crystallization process of ZnO incorporated TMA-A zeolite was analyzed by X-ray diffraction (XRD). The incorporated nano-sized ZnO crystals and the crystallinity of TMA-A zeolite were evaluated by transmission electron microscopy (TEM) and high resolution transmission electron microscopy (HRTEM). The size of the incorporated nano-sized ZnO crystals was 3~5 nm, while the TMA-A zeolite was 60~100 nm. The bonding structure and absorption of the ZnO incorporated TMA-A zeolite were compared with the ZnO and TMA-A zeolite by the FT-IR analysis. Subsequentlly, the ZnO incorporated TMA-A zeolite showed the photoluminescent characteristics on the wavelengths of 330~260 nm and 260~230 nm by measurement of UV spectrophotometer.