• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.60-60
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• 2011

Giant magnetoresistance (GMR), tunneling magnetoresistance (TMR), and magnetic random-access memory (MRAM) are currently active research areas in spintronics. The high magnetoresistance and the high spin polarization (P) of electrons in the ferromagnetic electrodes of tunnel junction or intermediate layers are required. Magnetite, Fe3O4, is predicted to possess as half-metallic nature, P ~ 100% spin polarization, and has a high Curie temperature (TC~850 K). Experiments demonstrated that the P~($80{\pm}5$)%, ~($60{\pm}5$)%, and ~40-55% for epitaxial (111), (110) and (001)-oriented Fe3O4 thin films, respectively. Epitaxial Fe3O4 films may enable us to investigate the effects of half metals on the spin transport without grain-boundary scattering.In addition, it has been reported that the Verwey transition (TV, a first order metal-insulator transition) of 120 K in bulk Fe3O4 is strongly affected by many parameters such as stoichiometry and stress, etc. Here we report that the growth modes, magnetism and transport properties of Fe3O4 thin films were strongly dependent on the oxygen pressure during film growth. The average roughness decreases from 1.021 to 0.263 nm for the oxygen pressure increase from $2.3{\times}10-7$ to $8.2{\times}10^{-6}$ Torr, respectively. The 120 K Verwey transition in Fe3O4 was disappeared for the sample grown under high oxygen pressure.

• Journal of the Korean Society of Clothing and Textiles
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• v.26 no.11
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• pp.1605-1614
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• 2002

The purpose of this study was to identify the consumers who use the level of price as the indicator of the product quality. In order to implement the purpose of this study, Jeans market had been segmented by the mixture regression model, and price response function was calibrated for each segment. Based on the types of price response function, segments were allocated into one of two groups; the group using the level of price as the quality indicator or the group not using the level of price as that. Then, characteristics of both groups were compared in terms of product attributes and demographic variables. Data were co]looted from the sample of the 23o undergraduate and graduate students in Seoul. For the data analysis, mixture regression model, conjoint analysis, and t-test were used. As a result, jeans market was divided into 5 segments. Segment 1,2,3 were allocated into the group not using the level of price as the quality indicator while segment 4,5 were done into the other group. Significant differences existed between two groups in product attributes, not in demographic variables. Mixture model and conjoint analysis were proved to be an effective set of tools in market segmentation.

• The Journal of Asian Finance, Economics and Business
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• v.7 no.10
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• pp.161-169
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• 2020

The condition of mining companies that exploit natural resources in their business processes underline this research to emphasize on social and environmental issues. After twelve years of government regulation on CSR practices, this study investigates the factors that influence mining companies in disclosing information about corporate social responsibility based on legitimacy, stakeholders, and agency theory. Thus, independent variables are foreign ownership, company size, leverage, and the board of commissioners. The dependent variable is the corporate social reporting disclosure that is measured using GRI indexing. For sampling, we have used thirty-four Indonesian mining companies listed in IDX during the 2014-2018. out of which only fifty-two companies meet the sample criteria. All data should pass the classical assumption test to get the best estimator. Multiple linear regression is used to test the hypothesis, and the results show that the model is good, and can explain 60% of the dependent variable. Based on F-test, all four variables affect CSR practices simultaneously. The findings of this study suggest that foreign ownership and firm size influences CSR disclosure in a positive direction. However, this study did not support the hypothesis that leverage negatively affects CSR disclosure and board size measures positively affect CSR disclosure.

• Korean Journal of Materials Research
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• v.19 no.12
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• pp.674-679
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• 2009

Yttria stabilized zirconia single crystals show plastic deformation at high temperatures by activating dislocations. The plastic deformation is highly dependent on crystallographic orientation. When the samples were deformed at different orientations, stress-strain curves changed by operating different slip systems. The strength of samples was also highly dependent on crystallographic orientation, i.e., samples without yield drop showed higher strength than that of samples exhibiting yield drop. The slip systems in the sample deformed along <112>, <111> and <001> agreed with the theoretical values of the plastic deformation, following Schmid's Law. Dislocations play a major role in the plastic deformation of this crystal. At the early stages of plastic deformation, all samples exhibited dislocation dipoles and, in the later stages, dislocation interactions occurred by forming nodes, tangles and networks. In this study, three different orientations, [11-2], [111] and [001] were employed to explain the plastic deformation behavior. A microstructural analysis was performed to elucidate the mechanism of the plastic behavior of this crystal.

• Journal of the Korean Society for Precision Engineering
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• v.33 no.5
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• pp.363-369
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• 2016

We explored localized plasmonic field enhancements using nanowire patterns to improve the sensitivity of a surface plasmon resonance (SPR) sensor. Two different materials, gold and silver, were considered for sample materials. Gold and silver nanowire patterns were fabricated by electron beam lithography for experimental measurements. The wavelength SPR sensor was also designed for these experiments. The material-dependent field enhancements on nanowire patterns were first calculated based on Maxwell's equations. Resonance wavelength shifts were indicated as changes in the refractive index from 1.33 to 1.36. The SPR sensor with silver nanowire patterns showed a much larger resonance wavelength shift than the sensor with gold nanowire patterns, in good agreement with simulation results. These results suggest that silver nanowire patterns are more efficient than gold nanowire patterns, and could be used for sensitivity enhancements in situations where biocompatibility is not a consideration.

• Bulletin of the Korean Chemical Society
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• v.18 no.6
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• pp.628-631
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• 1997

The preparation and characterization of $Co(dmppz)_2(3,6-dbq)_2$ (dmppz=1,4-dimethylpiperazine; 3,6-dbq=3,6-di-tert-butyl-1,2-quinone) are established. Temperature-dependent magnetic moments (100-400 K), variable-temperature IR, and electronic spectra are presented to show that the title complex exhibits an equilibrium via a catechol to cobalt intramolecular electron transfer. At temperatures below 350 K, the charge distribution of the complex is $Co^Ⅲ(dmppz)_2(3,6-dbsq)(3,6-dbcat)$ (3,6-dbsq=3,6-di-tert-butyl-1,2-semiquinonato; 3,6-dbcat=3,6-di-tert-butylcatecholato) whereas at the temperature beyond 390 K, the complex is predominantly Co^Ⅱ(dmppz)_2(3,6-dbsq)_2$ form in the solid state. At the temperature range of 350-390 K a mixture of Co(Ⅲ) and Co(Ⅱ) redox isomers exist at equilibrium. The transition temperature (Tc) of Co(Ⅲ)/Co(Ⅱ) in solution is approximately 50° lower than that in the solid state. In particular, thermal analysis on solid sample of the complex discloses that the transition for the Co(Ⅲ)/Co(Ⅱ) is accompanied by the change in heat content of 12.30 kcal/mol.

• Journal of dental hygiene science
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• v.19 no.3
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• pp.147-153
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• 2019

Background: With increased interest in oral health, several efforts have been made to improve oral health conditions. To achieve this, needs for oral health must be precisely determined and accurately measured. Therefore, factors influencing both objective unmet dental needs, which were determined by experts, and perceived unmet dental needs, which were determined by patients, were examined in this study. Methods: Responses of 17,735 respondents aged greater than 19 years from the Korean National Health and Nutrition Survey collected using the fifth (2010~2012) rotation sample survey were analyzed. Based on the information collected from the survey and dental examination, we determined the associations between the independent (sex and socioeconomic level) and dependent variables using a chi-squared test. Moreover, ordinal logistic regression analyses on multiple categorical values were performed using perceived and objective dental needs as the dependent variables. Results: Generally, factors influencing both perceived and objective dental needs were similar. These included sex, household income, educational level, private insurance, and subjective oral health status. However, the high-income groups had lesser perceived and objective dental needs compared to the low-income groups. Furthermore, factors such as sex, educational level, and marital status had different influence on both needs. Conclusion: Generally, factors that affect perceived and objective dental needs were similar. To minimize unmet dental needs, factors influencing both perceived and objective dental needs should be examined for a broad dental insurance coverage, and efforts to prevent oral diseases are also required.

• Journal of Microbiology and Biotechnology
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• v.34 no.2
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• pp.349-357
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• 2024

Foodborne pathogens, like Listeria monocytogenes, continue to inflict substantial financial losses on the food industry. Various methods for detecting Listeria in food have been developed and numerous studies have been conducted to compare the different methods. But, in recent years, new Listeria species have been identified, and currently the genus comprises 26 species. Therefore, it would be a more accurate approach to re-evaluate existing detection methods by considering new species. The present investigation involved the analysis of 42 ready-to-eat (RTE) foods, encompassing a variety of food categories, such as mezes, salads, dairy products, and meat products, with the aim of ascertaining the presence of Listeria. Among the traditional culture-dependent reference methods, the ISO 11290 method was preferred. The process of strain identification was conducted with the API Identification System. Furthermore, to ascertain the existence of L. monocytogenes and Listeria spp., the samples underwent additional analysis employing the VIDAS Immunoassay System, ELISA, and RT-PCR methodologies. Thus, four alternative approaches were employed in this study to compare not only the different methods used to determine Listeria while taking into account the newly identified Listeria species, but also to assess the compliance of retail RTE food items with microbiological criteria pertaining to the genus Listeria. Based on the conducted analyses, L. monocytogenes was conclusively determined to be present in one sample. The presence of Listeria spp. was detected in 30.9% of the samples, specifically in Turkish cig kofte, sliced salami, and salads.

• Korean Journal of Clinical Pharmacy
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• v.27 no.1
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• pp.38-43
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• 2017

Objective: Seoul City has implemented the Safe Pharmacy in 2013. This study aimed to ascertain the success factors of the smoking cessation service of the Safe Pharmacy. Methods: The data for the smoking cessation registration cards were obtained from the pharmacies which participated in 2014 Safe Pharmacy. The sample included 289 smokers in 6 districts who participated at least one sessions of smoking cessation service. the service included both behavioral intervention and nicotine replacement therapy. In order to identify the effectiveness of the smoking cessation service, logistic regression analysis was used. The dependent variable was the success of quitting smoking at the 4th week. The independent variables included age, sex, employment, chronic disease, district, smoking amount, registration path, supporters for quitting smoking and number of service sessions. Results: Fifty eight point eight percent of the sample successfully quit smoking at the 4th week. Unemployment, higher smoking amount, and less service sessions were negatively related to the success of quitting smoking. There were differences in the success rate across districts. Age, sex, chronic disease, registration path, and anti-smoking supporters were not related to the success rate. Conclusion: Pharmacy can be an effective community resource for smoking cessation. Factors that could increase the effectiveness of smoking cessation service of the Safe Pharmacy and possible ways to enhance the participation of pharmacies in smoking cessation services were also discussed.

• Proceedings of the Korean Vacuum Society Conference
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• 2015.08a
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• pp.125.2-125.2
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• 2015

The evolution of oxidation states of vanadium is monitored with ambient pressure X-ray photoemission spectroscopy. As the pressure of oxygen gas and surface temperature change, the formations of various oxidation states of vanadium are observed on the surface. Under 100mTorr of the oxygen gas pressure and 523K of sample temperature, VO2 and V2O5 are formed on the surface. The temperature-dependent resistance measurement on grown sample shows a clear metal-insulator transition near 350K. In addition, the measurement of Raman spectroscopy displays the structural change from monoclinic to rutile structures across the phase transition temperature.