• Journal of Powder Materials
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• v.11 no.2
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• pp.111-117
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• 2004

The oxidation behavior of 91 WC-9Co hardmetal in weight percentage has been studied in the present work as a part of the development of recycling process. The morphological and compositional changes of the WC-Co hardmetal with oxidation time at 90$0^{\circ}C$ were analyzed by using surface observation and X-ray diffraction. respective]y. As the oxidation time increased, the WC-Co hardmetal was continuously expanded to form porous oxide mixtures of $CoWO_4$ and $WO_3$. The morphology of porous oxide mixture was basically dependent on initial shape of the WC-Co hardmetal. From thermo-gravimetric (TG) analysis, it was found that the oxidation rate was increased with increasing oxidation temperature and oxygen content in the flowing atmospheric gas. The fraction of oxidation versus time curves showed S-curve relationship at a given of oxidation temperature. These oxidation behaviors of the WC-Co hardmetal were discussed in terms of previously proposed kinetic models.

• Archives of Pharmacal Research
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• v.23 no.4
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• pp.329-331
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• 2000

4-(p-Chlorophenyl)tetralone (6) and 7-chloro-5-(p-chlorophenyl)tetralone (9) are key intermediates for the development of benzazepinone derivative haftens. These compounds could be synthesized from 4-phenyltetralone derivatives by triflic acid catalyzed Friedel-Crafts reaction. The reaction mechanism of Friedel-Crafts alkylation/acylation with lactones in triflic acid is presented. According to our tentative research, ring opening of protonated lactone (2) occurs in alkyl cleavage and the rate of the reaction is not dependent on concentration of triflic acid. So, alkylation of lactone in Friedel-Crafts reaction is presumed to be $A_{AL}$ 1. In second step, intramolecular acylation of the intermediates 4 to 6, 4 can be transformed to a triflic acid-carboxylic anhydride and then the cyclization is undergone after leaving of the triflate anion.

• Journal of Environmental Science International
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• v.16 no.7
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• pp.779-784
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• 2007

Dinitrophenol is preventing cells from making energy for growth and it has been suggested that pH may be important in mitigating effects of uncouplers. The effect of pH on toxicity of dinitrophenol at high concentration was investigated, over a pH range of 5.7 to 8.7. DNP inhibition was found to be strongly dependent on mixed liquor pH. The DNP degradation rate was highest in the pH range of 7.0 to 7.8; at pH 6.0 degradation of 0.41 mM dinitrophenol was significantly inhibited; at pH <5.7, dinitrophenol degradation was completely inhibited after approximately 25% of the dinitrophenol was degraded. However no significant effect of pH variation was seen on glucose uptake by the activated sludge mixed culture.

• Culinary science and hospitality research
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• v.4
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• pp.57-72
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• 1998

Now a days, people are interested in tourism and leisure activity more and because of the increase of pastime and disposable income as a result of current economic growth. The importance of service industry in getting more serious thereby food industry, especially fastfood, is becoming popular in Korea. Food industry in Korea has been showing high growth rate in both quantity and quality for 10 years and fastfood chains maintains radical growth with 50% being forecasted that they will make huge market in Korea. Therefore, fastfood industry seems to be promising industry which has high potentials. This rapid growth of fastfood industry has been solving a lot of problems such as insanitation, low nutrition, and bad service quality and its positive aspects which make revolutional changes in production and sales are emphasized because it made industrialization with innovative system. So various menu development and service marketing strategy are really need to manage chains for the situation in Korea. Thus, the competitiveness of fastfood clams is dependent on the location of restaurant and the quality of various products. If the marketing strategy for fastfood industry need to established. constant studies should be done to resolve these problems.

• Journal of Ocean Engineering and Technology
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• v.10 no.2
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• pp.42-52
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• 1996

소성스핀을 취급하기 위한 이론을 살펴보면 개념적으로 현저히 다른 세가지로 압축된다. 또한 재료직조 현상이 소성스핀의 근원이라고 알려져 있지만, 그 지배인자와 발생근원에 대하여 아직 충분히 연구되어 있지 않다. 따라서 앞으로의 연구에 올바른 방향을 제시하기 위하여 소성스핀의 기본적인 거동에 대한 연구가 요구된다. 본 연구에서는 체심입방격자 다결정의 소성스핀 시뮬레이션을 통하여, 소성스핀의 거동을 조사하였는데, 재료직조, 변형경화, 변형속도, 하중역전 등의 영향을 검토하였다. 소성발생원인으로 재료직조현상이 강조되었고, 이에 관련한 주요지배인자를 제시하였다. 무차원 소성스핀은 변형속도, 재료경화에 영향을 받으나 재료직조와 관련한 인자와 비교하여 그 영향이 작게 나타났다.

• Journal of the Korean Ceramic Society
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• v.43 no.8 s.291
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• pp.479-485
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• 2006

The residual stress changes on thermo-mechanical loading in the interface region of the Thermal Barrier Coating (TBC)/Thermally Grown Oxide (TGO)/Bond Coat (BC) were calculated on the TBC-coated superalloys using a Finite Element Method (FEM). It was found that the residual stress of the interface boundary was dependent upon mainly the oxide formation and the swelling rate of the oxide by creep relaxation. During an oxide swelling, the relaxation of residual stress which is due to creep deformation increased the TBC's life. In the case of the fine grain size of TGO scale, the TBC stresses piled up by oxide swelling could be relaxed by diffusional creep effect of TGO.

• Journal of the Korean Ceramic Society
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• v.25 no.2
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• pp.95-100
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• 1988

Single crystals of sapphire were grown from solution by slow cooling method using B2O3 and PbO as flux agents. The morphology of grown crystals was tube, rhombohedral, or hexagonal-plate. It was found that the morphology and the size of grown crystal were highly dependent on the amount of fluxes in the solution, the ratio of B2O3 vs. PbO, and cooling rate.

• Korean Journal of Health Education and Promotion
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• v.32 no.5
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• pp.53-62
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• 2015

Objectives: The purpose of this study was to examine the associations among self-rated health and socioeconomic status. Methods: Analyses were conducted based on cross-sectional data obtained from the Korea Youth Risk Behavior Web-based Survey. A total of 79,202 students aged 12 to 18 years participated in the study and there was a response rate of 95.5%. Separate logistic regression analyses were performed on each gender group based on a set of independent variables. Those being: the level of parental education level; family affluence scale; subjective household economic status; and subjective school achievement with SRH as the dependent variable. Results: Multivariate analyses revealed significant associations between each SES and adolescent SRH after controlling for other covariates. However, in the models that included all SES indicators, subjective household economic status and subjective school achievement remained significant in boys and girls. Conclusions: The findings demonstrated that subjective SES indicators are more closely related to adolescent SRH when compared with objective indicators.

• 한국정보디스플레이학회:학술대회논문집
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• 2009.10a
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• pp.942-944
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• 2009

Blue phase shows several different reflection colors from the randomly oriented domains and crystal direction. Also there are variations in the size of domains. The domain size is dependent on the temperature gradient. With smaller cooling rate of temperature, the domain size was increased compared with rapid cooling. With injection of light of specific wavelength, we find that the diffraction patterns were occurred around the light spot in the cell of blue phase. It was supposed to be from the matching of the phase retardation and domain size. However, actually the diffraction pattern is reflecting the lattice structure in double twist of the blue phase. The lattice constant from the radius of diffraction patterns shows very similar one from the reflection spectrum, which indicates the internal lattice constant in double twist of the blues phase.

• Journal of Information Display
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• v.8 no.3
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• pp.11-16
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• 2007

Theoretical simulations of spatial distribution of charge carriers and recombination rate, and J-V characteristics of the multi-layer organic light emitting diodes are carried out. Drift-diffusion current transport, field-dependent carrier mobility, exponential and Gaussian trap distribution, and Langevin recombination models are included in this computer model. The simulated results show good agreement with the experimental data confirming the validity of the physical models for organic light emitting diodes.