• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.361-362
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• 2005

Antimony doped tin oxide(ATO) nano powders have been synthesized by homogeneous precipitation method using $SnCl_4\cdot5H_2O$ for precursor, $SbCl_3$ as doped material and urea. The hydrolysis of urea and conductive mechanism and Heat treatment was performed at the temperature from $500^{\circ}C$ to $700^{\circ}C$ in air. The ATO nano powders are characterized by means of Thermogravimetry differential thermal analyzer (TG-DTA), X-ray diffraction (XRD), Brunauer, Emmett, and Teller adsorption (BET), Scanning electron microscopy (SEM) ATO nano powders with an average size of nm and the highest surface area 129 $m^2g^{-1}$ are obtained.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2005.07a
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• pp.292-293
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• 2005

An electromagnetic memory effect observed in superconducting YBCO system was studied. From the measurement of differential conductance, it was cleared that the mechanism of electromagnetic memory can not be explained by using conventional flux flow model. By changing the density of external magnetic flux, changes in inductance of a coil in which a superconducting bar is inserted were also measured. It was concluded that the electromagnetic memory effect aries from the interaction between the trapped magnetic flux and the weak link of the filament formed in the superconducting bar.

• Tribology and Lubricants
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• v.13 no.3
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• pp.73-84
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• 1997

ER clutch is a device using ER fluid, so called "intelligent material" and is a controlled system with electric field strength. Currently, the temperature of ER fluid increases and affects the performance of ER clutch when ER clutch is operating. This study was undertaken to estimate this performance variation due to temperature rise of ER fluid. An analytic heat transfer model of concentric cylinder type ER clutch was developed and with this model, effects of changing geometric, kinetic parameters of ER clutch and ER fluid properties were described. In conclusion, compared with neglecting thermal effects, a performance of ER clutch was very differential and for uniform performance of ER clutch, we have to improve thermal stability of ER fluid. ER fluid.

• Bulletin of the Korean Chemical Society
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• v.12 no.4
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• pp.368-370
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• 1991

The electrochemical behavior and the complex formation between N$i^{2+}$ and 1,7-diazs-15-crown-5 and 1,10-diaza-18-crown-6 in acetonitrile solution have been studied by DC polarography, differential puke polarography and cyclic voltammetry. Nickel(Ⅱ) complexes gave a single well-defined wave. The formation constants of their complexes were 1$0^{4.89} and 10^{3.86}$, respectively. Nickel(Ⅱ) ion was found to form complexes of 1-to-1 composition with 1,7-diaza-15-crown-5 and 1,10-diaza-18-crown-6. In addition, reduction steps were irreversible and the reduction current were diffusion controlled. The electrochemical reduction mechanism of Ni(Ⅱ)-macrocyclic diaza-crown complexes in acetonitrile solution is estimated.

• Advances in materials Research
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• v.2 no.2
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• pp.111-118
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• 2013

The changes of plastic plateau in the stress-strain curves of annealed polypropylene (PP) films during stretching under room temperature were followed and the corresponding melting properties and microstructure were characterized by differential scanning calorimetry (DSC) and scanning electron microscopy (SEM). It was found that during stretching the plastic plateau disappeared progressively with the increase of drawing ratio. At the same time, the endotherm plateau in DSC curves also disappeared progressively. The presence of the plastic plateau was attributed to the stretching of unstable crystalline part which was formed by tie chains around initial row-nucleated lamellae structure during annealing. During stretching, the unstable part was stretched and converted to bridges connecting separated lamellae. There was direct relationship between the disappearance of plastic plateau and pore formation.

• Journal of Magnetics
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• v.21 no.4
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• pp.529-536
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• 2016

Magnetically suspended sensitive gyroscopes (MSSGs) provide an interesting alternative for achieving precious attitude angular measurement. To effectively reduce the measurement error caused by dynamic imbalance, this paper proposes a novel compensation method based on analysis and modeling of the error for a MSSG. Firstly, the angular velocity measurement principle of the MSSG is described. Then the analytical model of dynamic imbalance error has been established by solving the complex coefficient differential dynamic equations of the rotor. The generation mechanism and changing regularity of the dynamic imbalance error have been revealed. Next, a compensation method is designed to compensate the dynamic imbalance error and improve the measurement accuracy of the MSSG. The common issues caused by dynamic imbalance can be effectively resolved by the proposed method in gyroscopes with a levitating rotor. Comparative simulation results before and after compensation have verified the effectiveness and superiority of the proposed compensation method.

• Clinical and Experimental Pediatrics
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• v.64 no.1
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• pp.3-11
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• 2021

There is a growing body of literature on the adverse health effects of ambient air pollution. Children are more adversely affected by air pollution due to their biological susceptibility and exposure patterns. This review summarized the accumulated epidemiologic evidence with emphasis on studies conducted in Korea and heterogeneity in the literature. Based on systematic reviews and meta-analyses, there is consistent evidence on the association between exposure to ambient air pollution and children's health, especially respiratory health and adverse birth outcomes, and growing evidence on neurodevelopmental outcomes. Despite these existing studies, the mechanism of the adverse health effects of air pollution and the critical window of susceptibility remain unclear. There is also a need to identify causes of heterogeneity between studies in terms of measurement of exposure/outcome, study design, and the differential characteristics of air pollutants and population.

• Asian Journal for Public Opinion Research
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• v.10 no.2
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• pp.76-101
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• 2022

Despite the increasing use of digital media and their powerful impact on risk management during recent outbreaks of emerging infectious diseases, the question of how digital media exposure influences preventive behaviors has not been fully explained. Using the appraisal tendency framework and protection motivation theory as theoretical frameworks, we theorized the affective and cognitive mechanisms under which the differential roles of three negative emotions (fear, anger, worry) on two cognitive appraisals (perceived threat and perceived efficacy) were examined. Based on data collected from a survey of 1,500 South Koreans during the COVID-19 pandemic, we found that while worry and anger increased perceived efficacy, fear reduced perceived efficacy. The results also showed that although exposure to COVID-19 information via digital formats increased preventive behavioral intention in general, digital media use for COVID-19 information had a negative influence on preventive behavioral intention through the sequential mediation of fear and perceived efficacy.

• Annual Conference of KIPS
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• 2022.05a
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• pp.264-267
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• 2022

Recently, federated learning (FL) has increased prominence as a viable approach for enhancing user privacy and data security by allowing collaborative multi-party model learning without exchanging sensitive data. Despite this, most present FL systems still depend on a centralized aggregator to generate a global model by gathering all submitted models from users, which could expose user privacy and the risk of various threats from malicious users. To solve these issues, we suggested a safe FL framework that employs differential privacy to counter membership inference attacks during the collaborative FL model training process and empowers blockchain to replace the centralized aggregator server.

• Journal of East-West Nursing Research
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• v.29 no.2
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• pp.172-184
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• 2023

Purpose: The purpose of this study was to identify the subjective relapse experiences of patients with alcohol use disorder in one's life context. Methods: A Q methodology was used to analyze the subjectivity of relapse experiences among 55 participants with alcohol use disorder. Fifty-five Q-statement were derived from interviews and literature review. Q-statements were classified into normally distributed shapes using a 9-point scale. Data were analyzed using the QUANL program. Results: Four types of relapse experiences were identified: failure to self-regulation drinking cravings, fear of relapse and awareness of the need for treatment, drinking as a coping mechanism and defensive coping, and lack of motivation to change drinking behavior. Conclusion: The results of this study suggest that patients with alcohol use disorder need a differential approach based on four types of relapse experiences in the recovery process.