• Journal of Industrial Convergence
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• v.15 no.2
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• pp.27-36
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• 2017

In this study, we analyzed service quality factors of O2O delivery app based on Kano model and survey, and classified service quality into several dimensions. As a result of the analysis, the one dimensional quality factors were accurate information transmission, variety of restaurants, diversity of payment methods, diversity of menu selection, discomfort resolution, kindness of service, taste and quality of food, hygiene and cleanliness, Attractive quality factors such as updated information, reliable reviews, various ordering methods, fast delivery, brand image, discount point payment and accumulation. Although the must-be quality factor did not appear, it turned out that the discomfort resolution was close to the must-be quality factor. The indifferent quality factors were informational services, events and promotions. The O2O delivery app market is continuing to grow and competition is getting more and more intense. The results of this study will help O2O delivery app vendors to establish strategies to focus on certain quality of service factors.

• Journal of the Korean Ceramic Society
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• v.50 no.1
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• pp.57-62
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• 2013

We investigated the thermal and electrical properties of the $B_2O_3-ZnO-Bi_2O_3$ glass system as a sealing material in sheath heater modules. A composition with over 90 wt% $Bi_2O_3$ in the $B_2O_3-ZnO-Bi_2O_3$ system was glassified by controlling the cooling rate. The glass transition temperature and thermal expansion coefficient in bismate glass could be controlled by the minor ingredients of ZnO, $SiO_2$, $BaO_2$, and $K_2O$. The $B_2O_3-ZnO-Bi_2O_3$ glass system bonded well to metal, and bismate glass insulating properties were comparable to those of bismate glass $B_2O_3-ZnO-PbO$ glass system in a sheath heater module.

• Journal of the Korean Ceramic Society
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• v.52 no.1
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• pp.19-22
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• 2015

The joining behavior of YSZ ceramics to the glasses used in the $9Al_2O_3-24ZrO_2-51SiO_2-16R_2O$ and $9Al_2O_3-24ZrO_2-51SiO_2-7La_2O_3-9R_2O$ (wt%) glass systems was investigated. The glass transition and softening temperatures were determined to be $430^{\circ}C$ and $760^{\circ}C$, respectively. The behavior of the contact angle was inversely proportional to an increase in the temperature. The Zr element in YSZ acted as a nucleation agent and contributed to the bonding behavior at the interface.

• Korean Journal of Clinical Laboratory Science
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• v.52 no.2
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• pp.150-157
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• 2020

The protective effects of a Celastrus orbiculatus Thunb (CO) extract against manganese dioxide (MnO₂)-induced cytotoxicity in cultured C6 glioma cells were examined. This study assessed the antioxidative effects, including the suppressive ability of lipid peroxidation (LP), the inhibitory ability of xanthine oxidase (XO), and the cell viability. MnO₂ decreased the cell viability remarkably in a dose-dependent manner. The XTT₅₀ value was determined to be 146.7 μM in these cultures. The cytotoxicity of MnO₂ was calculated to be mid-toxic using Borenfreund and Puerner's toxic criteria. Kaempferol (KAE) increased the cell viability damaged by MnO₂-induced cytotoxicity significantly. Regarding the protective effects of the CO extract on MnO₂-induced cytotoxicity, the CO extract increased cell viability significantly compared to the MnO₂-treated group. The CO extract also had inhibitory abilities against lipid peroxidation (LP) and xanthine oxidase (XO). From these findings, oxidative stress is involved in the cytotoxicity of MnO₂. The CO extract effectively blocked the cytotoxicity induced by MnO₂ via its antioxidative effects. Conclusively, natural resources, such as the CO extract, might be a useful agent for the diminution or improvement of the heavy metal cytotoxicity correlated with disease through oxidative stress, such as MnO₂, a Parkinsonism inducer.

• Journal of the Korean Ceramic Society
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• v.30 no.10
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• pp.811-818
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• 1993

Al2O3/ZrO2-Spinel composites were prepared by infiltrating magnesium sulfate solution into the porous preform made from Al2O3-20wt% ZrO2 composite powders derived through an emulsion route. The microstructure and composition of the modified composites could be controlled by manipulating the presingtering temperature of the preform, infiltration time, and so on. It was found that spinel phases were concentrated near the surface than in the interior of the Al2O3/ZrO2-Spinel composites infiltrated for 6hrs, while spinel phases were uniformly distributed in the comosites infiltrated for 2 days. The relative density and fracture toughness of the composite infiltrated for 6 hrs were 98.6% and 7.2MN/m3/2, respectively.

• Journal of the Korean Ceramic Society
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• v.29 no.5
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• pp.335-340
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• 1992

Undoped PbTiO3 ceramics was successfully prepared by using sol-gel process, which had not been fabricated due to its microcracks created by anisotropic stress during phase transition from cubic to tetragonal phase. Fabrication of undoped PbTiO3 ceramics via sol-gel processing was very much affected by the PbO content of the samples as well as PbO vapor from sintering atmosphere. Excess PbO was found to promote rapid grain growth in PbTiO3 ceramics. After sintering at 1100$^{\circ}C$ average grain size of PbTiO3 ceramics with excess PbO was about 8 times greater than that of stoichiometric composition, which may be due to PbO liquid phase from excess PbO.

• Journal of the Korean Ceramic Society
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• v.26 no.4
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• pp.568-574
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• 1989

Effect of PbO addition on sintering and piezoelectric properties at 0.45Pb(Ni1/3Nb2/3)O3-0.40PbTiO3-0.15PbZrO3 composition which is tetragonal phase was investigated. In this composition, Porosity and dielectric constant were increased with excess PbO addition, but Kp and d31 was not changed. These variation of physical properties could be interpreted as composition change of solid grains from tetragonal to MPB region due to amount of PbO-rich liquid changing.

• Journal of the Korean Ceramic Society
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• v.33 no.9
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• pp.1038-1044
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• 1996

The variations of sintering and electrical characteristics of semiconducting BaTiO3 ceramics with sintering agents added were investigated comparing the case of BaB2O4 addition to BN and TiO2 addition. When BaB2O4 added in BaTiO3 ceramics the densitifcation of specimen could be acheived more easily and recvealed the better PTCR characteristics than BN and TiO2 addition. As increase of addition of BaB2O4 in BaTiO3 spec imens the slope of resistivity jump also increased but the temperature of maximum resistivity decreased, It was supposed that addition of BaB2O4 led to increase of Ns (acceptor state density) value at grain boundaries.

• Journal of the Korean Ceramic Society
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• v.28 no.5
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• pp.406-414
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• 1991

The composition of base glass was selected as MgO 8, Al2O3 24, SiO2 68 in weight percent. TiO2 and ZrO2 were added to the base glass to investigate their effects as nucleating agents. In the case of ZrO2 addition, the optimum temperature for nucleation, which was related to the precipitation of tetragonal ZrO2, was 80$0^{\circ}C$. The optimum growth condition for the crystal was 87$0^{\circ}C$ for 8 hrs, and the major crystal phases precipitated in the samples were $\beta$-quartz ss. and mullite. The light transmissivity turned out to be around 80 per cent. On the other hand, when the TiO2 was added, it was difficult to determine the nucleating temperature, because the samples turned easily into translucency during the heat treatment. Therefore, it was almost impossible to retain transparency in the samples. The light transmissivity was below 30 per cent.

• Journal of the Korean Vacuum Society
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• v.9 no.1
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• pp.24-29
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• 2000

MgO thin films were deposited on soda lime glass substrates by rf magnetron sputtering using a MgO target at various oxygen flow ratios in order to probe the relationship between MgO film properties and discharge characteristics. MgO films have a tendency to form microstructures with a preferred growth orientation of (200) with increasing oxygen flo ration up to 0.1 $O_2$/(Ar+$O_2$). MgO film obtained at 0.1[$O_2$/(Ar+$O_2$)] was found to be fully stoichiometric. The stoichiometric MgO film was observed to have relatively very clean surface and grains of large size and contain almost no hydroxyl group. The AC PDP with fully stoichiometric MgO film showed lower firing and sustain voltages than those with magnesium-rich or oxygen-rich MgO films, being largely attributed to the larger grain size and the minimized hydroxyl group.