• Journal of the Korean Applied Science and Technology
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• v.32 no.1
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• pp.1-6
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• 2015

We investigated green phosphorescent organic light-emitting diodes with stepwise doping to improve efficiency roll-off and operational lifetime by efficient distribution of triplet excitons. The host material which was 4,4,N,N'-dicarbazolebiphenyl (CBP) of bipolar characteristic that can control the carrier in emitting layer (EML). When the EML devided into four parts with different doping concentration, each devices shows various efficiency roll-off and lifetime enhancement. The distribution of the carrier and excitons in the EML can be confirmed by using stepwise doping structure. The properties of device C exhibited luminous efficiency of 51.10 cd/A, external quantum efficiency of 14.88%, respectively. Lifetime has increased 73.70% compared to the reference device.

• Journal of the Korea Society of Computer and Information
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• v.28 no.5
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• pp.171-177
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• 2023

This study aims to provide useful information for prevention of doping by investigating and verifying relationships among demographic factors such as athletic career and experience of anti-doping education, controlled motivation, attitude toward anti-doping, perceived behavioral control factors and doping intentions to verify factors affecting doping intentions of domestic elite athletes based on the advance studies that have been carried out various theoretical approaches so far. Method: This study analyzed using SPSS 27.0 program. First, this study confirmed a multicollinearity problem by conducting Pearson's correlation analysis to examine correlation between variables. And this study conducted stepwise multiple linear regression to confirm how the variables affect doping intentions. Result: Study results show that all factors such as athletic career, experience of anti-doping education, controlled motivation, attitude toward anti-doping and perceived behavioral control have a significant impact on doping intentions, and this study verified significant impact by putting variables in order of each influence. As a result of verification, this study confirmed that controlled motivation has the greatest influence, and perceived behavioral control toward doping, experience of anti-doping education, attitude toward and athletic career came next in order.

• Mass Spectrometry Letters
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• v.9 no.1
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• pp.30-36
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• 2018

A quantitation method for free amino acids in human serum was developed using a stepwise-dilution method and a bimodal cation exchange (CEX)/hydrophilic interaction liquid chromatography (HILIC)-tandem mass spectrometry system equipped with an electrospray ionization source (ESI/MS/MS). This method, which was validated using quality control samples, was optimized for enhanced selectivity and sensitivity. Dithiothreitol (DTT) was used as a reducing agent to prevent the oxidation of a serum sample ($50{\mu}L$), which was then subjected to stepwise dilution using 3, 30, and 90 volumes of acetonitrile containing 0.1% formic acid. Chromatographic separation was performed on an Imtakt Intrada Amino Acid column ($50mm{\times}3mm$, $3{\mu}m$) in mixed mode packed with CEX and HILIC ligands embedded in the stationary phase. Underivatized free amino acids were eluted and separated within 10 min. As a result of the validation, the precision and accuracy for the inter- and intraday assays were determined as 2.11-11.51% and 92.82-109.40%, respectively. The lowest limit of quantification (LLOQ) was $0.5-4.0{\mu}g/mL$ and the matrix effect was 80.22-115.93%. The proposed method was successfully applied to the quantitative analysis of free amino acids in human serum.

• Journal of Digital Convergence
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• v.16 no.3
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• pp.553-560
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• 2018

This study aimed to quantify the attitude toward doping among handball players and to identify the influence of players' demographic information, knowledge of doping, education of anti-doping on the attitudes toward doping. 385 elite handball players (193 adolescent players, 165 adult players) were participated in this study and filled in the questionnaire about demographic information, knowledge of doping, education of anti-doping and Performance Enhancement Attitude Scale (PEAS). Collected data were analyzed by Stepwise multiple linear regression. Adult players were more generous about doping than adolescents, and, adolescent players' attitudes toward doping were influenced by their gender and age. In adults, attitudes toward doping were related with only the gender. These results would be useful information to develop the effective anti-doping strategy for handball play.

• Journal of Digital Convergence
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• v.17 no.5
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• pp.391-398
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• 2019

This study aimed to investigate the factors that influence the attitude toward doping and to provide useful information for developing a doping prevention program suitable for Korean athletic players. One hundred and seventy-two players who enrolled in Korea Association of Athletics Federations were participated in this study and they filled in the questionnaire about demographic factors, information on doping, perfectionism, and perceived motivational climate. Collected data were analyzed by using stepwise multiple linear regression for exploring the main factor that affect the attitude toward doping depending on field and track events. All adult players have more permissive attitude toward doping than adolescents. In track event, while players who are sensitive to coach's criticism have more permissive attitude toward doping, players who focused on personal standards have more repressive attitude toward it. These results would be useful to develop anti-doping strategy for Korean field and track players.