Prevalence of cyberbullying and predictors of cyberbullying perpetration among Korean adolescents

Lee, Changho,Shin, Namin Elsevier 2017 Computers in Human Behavior Vol.68 No.-

<P><B>Abstract</B></P> <P>This study aimed to investigate the prevalence of cyberbullying and factors in cyberbullying perpetration with a national sample of 4000 adolescents selected through multi-stage cluster sampling. The respondents were 2166 boys (54.1%) and 1834 girls (45.9%) in 7<SUP>th</SUP>–12th grades at 24 middle and 24 high schools across South Korea. Statistical analyses of the survey data are summarized as follows. First, 34% of the respondent students were involved in cyberbullying as bullies (6.3%), victims (14.6%), or both bullies and victims (13.1%). Boys had a higher percentage of cyberbullying perpetration than girls. Second, variables for time spent on chat services and Social Network Services (SNS), the experience of being cyberbullied, and offline bullying perpetration tended to increase the probability of students being perpetrators of cyberbullying. However, the cognitive empathy variable contributed to decreased cyberbullying perpetration behaviors. Third, the variables of parental attachment and satisfaction with school life had little impact on perpetration of cyberbullying. These results were discussed to improve the understanding of the characteristics of cyberbullying among Korean adolescents and the youth population in general, while providing educators and researchers information on cyberbullying with practical consideration to its prevention.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Boys had a higher percentage of cyberbullying perpetrations than girls. </LI> <LI> Girls exerted relational violence through chat services more than boys did. </LI> <LI> The cognitive empathy variable contributed to decreased cyberbullying perpetration behaviors. </LI> <LI> Cyberbullied experiences were positively related to cyberbullying perpetration. </LI> </UL> </P>

Simple Data Analytics Approach Coupled with Larson–Miller Parameter Analysis for Improved Prediction of Creep Rupture Life

Changho Lee,Taejoo Lee,Yoon Suk Choi 대한금속·재료학회 2023 METALS AND MATERIALS International Vol.29 No.11

Machine learning of the creep rupture life dataset, which consists of test temperatures, stresses and rupture lives, receivedless attention in the community due to numerous physics-based and empirical models already available for the prediction ofthe creep rupture life, and a limited number (typically about 10 to 40) of available creep rupture life data points consideredto be too small to be trained for the reliable prediction. A simple data analytics approach was developed for the quick andreliable assessment of the creep rupture life. The proposed approach involves linear regression as a major algorithm and thefour features [two generic features (temperature (T) and stress (σ)) and two physics-informed features (ln σ and −1/T)], andexhibited superior creep rupture life predictions (validated by the 41 creep datasets of ferritic Cr steels) without any violationof creep phenomenology and data overfitting. In particular, the proposed approach was extremely useful to assess thefidelity of the Laron–Miller relation for a given creep rupture life dataset and to find an optimum Larson–Miller constantthat minimizes a deviation from the ideal Larson–Miller relation. An analytical model was also developed based on curvefitting of Larson–Miller parameters calibrated by the optimum Larson–Miller constant. The proposed analytical model gaveadditional improvement in creep rupture life prediction, particularly for creep datasets, of which creep rupture lives wereslightly less predicted by the data analytics approach. The two proposed models provided a synergistic effect in creep rupturelife prediction when interactively used.

Liquid Cooling of Laser-driven Head Light Employing Heat Spreader Manufactured by 3D Metal Printing

Lee, Yonghan,Park, Sangki,Byun, Changho,Lee, Sun-Kyu SPRINGER 2018 INTERNATIONAL JOURNAL OF PRECISION ENGINEERING AND Vol. No.

Geotechnical and Geoacoustic Properties of Volcanic Soil in Ulleung Island, East Sea of Korea

Lee, Changho,Byun, Yong-Hoon,Lee, Jong-Sub Taylor Francis 2016 Marine georesources & geotechnology Vol.34 No.7

<P>The unique material properties of volcanic soils may cause stability problems within the soil. However, few studies have examined the composition and engineering characteristics of volcanic soils below sea level. The objective of this study is to investigate the engineering properties of volcanic soils sampled from Ulleung Island. For the volcanic soils, the index properties, particle geometry, and mineralogy are analyzed in the laboratory. An oedometer cell incorporated with bender elements is used to measure the small-strain stiffness and compressibility of the volcanic soils. To obtain the large strain strength parameter and hydraulic conductivity of the volcanic soils, direct shear tests, and constant head permeability tests are performed. The experimental results show that the basic index properties of volcanic soils sampled from Ulleung Island are very similar to the values of previously published reference data: poorly graded with a median grain size, very low fine fraction, and slightly high specific gravity. In addition, the particle surface texture features and elementary analysis indicates a dark grain color, small pits or holes in the grain, and relatively low SiO2 and high Fe2O3 contents. The friction angle of the volcanic soils depends on the relative density, and the hydraulic conductivity varies according to e(3)/(1+e) and D-10(2). The characterization of the electrical properties in Ulleung Island needs to be conducted with caution due to the high Fe2O3 content in the volcanic soils.</P>

Over 40 cd/A Efficient Green Quantum Dot Electroluminescent Device Comprising Uniquely Large-Sized Quantum Dots

Lee, Ki-Heon,Lee, Jeong-Hoon,Kang, Hee-Don,Park, Byoungnam,Kwon, Yongwoo,Ko, Heejoo,Lee, Changho,Lee, Jonghyuk,Yang, Heesun American Chemical Society 2014 ACS NANO Vol.8 No.5

<P>Green CdSe@ZnS quantum dots (QDs) of 9.5 nm size with a composition gradient shell are first prepared by a single-step synthetic approach, and then 12.7 nm CdSe@ZnS/ZnS QDs, the largest among ZnS-shelled visible-emitting QDs available to date, are obtained through the overcoating of an additional 1.6 nm thick ZnS shell. Two QDs of CdSe@ZnS and CdSe@ZnS/ZnS are incorporated into the solution-processed hybrid QD-based light-emitting diode (QLED) structure, where the QD emissive layer (EML) is sandwiched by poly(9-vinlycarbazole) and ZnO nanoparticles as hole and electron-transport layers, respectively. We find that the presence of an additional ZnS shell makes a profound impact on device performances such as luminance and efficiencies. Compared to CdSe@ZnS QD-based devices the efficiencies of CdSe@ZnS/ZnS QD-based devices are overwhelmingly higher, specifically showing unprecedented values of peak current efficiency of 46.4 cd/A and external quantum efficiency of 12.6%. Such excellent results are likely attributable to a unique structure in CdSe@ZnS/ZnS QDs with a relatively thick ZnS outer shell as well as a well-positioned intermediate alloyed shell, enabling the effective suppression of nonradiative energy transfer between closely packed EML QDs and Auger recombination at charged QDs.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/ancac3/2014/ancac3.2014.8.issue-5/nn500852g/production/images/medium/nn-2014-00852g_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/nn500852g'>ACS Electronic Supporting Info</A></P>

A Reanalysis of the Double Object Constructions in Mandarin Chinese - Using the Light verb Phrase and Applicative Phrase

Lee, ChangHo(李彰浩),Lee, JiHyoun(李知玹) 한국중어중문학회 2021 한국중어중문학회 우수논문집 Vol.- No.-

The study of double object construction(DOC) has long been addressed in the field of generative grammar. In this paper, several previous analyses of the Chinese DOC and their problematic issues were examined(section 2), and then new ways to solve these problems were sought(section 3). In particular, in section 3, the syntactic structure of the Chinese DOC was re-analyzed using the light verb phrase and the applicative phrase. Relying on this, the DOC in Mandarin Chinese is derived on the basis of the structure of [<SUB>vP</SUB> Subject [<SUB>v</SUB> CAUSE [<SUB>vApplP</SUB> Indirect Object [<SUB>vAppl</SUB> BECOME/給 [RECEIVE/AFFECTED] [<SUB>VP</SUB> ...Direct Object...]]]]].

Real-time monitoring of SPT donut hammer motion and SPT energy transfer ratio using digital line-scan camera and pile driving analyzer

Lee, Changho,An, Shinwhan,Lee, Woojin Springer-Verlag 2014 Acta geotechnica Vol.9 No.6

Characteristics of Rubber-Sand Particle Mixtures according to Size Ratio

Lee, Changho,Truong, Q. Hung,Lee, Woojin,Lee, Jong-Sub American Society of Civil Engineers 2010 Journal of materials in civil engineering Vol.22 No.4

Biodegradable Photonic Melanoidin for Theranostic Applications

Lee, Min-Young,Lee, Changho,Jung, Ho Sang,Jeon, Mansik,Kim, Ki Su,Yun, Seok Hyun,Kim, Chulhong,Hahn, Sei Kwang American Chemical Society 2016 ACS NANO Vol.10 No.1

<P>Light-absorbing nanoparticles for localized heat generation in tissues have various biomedical applications in diagnostic imaging, surgery, and therapies. Although numerous plasmonic and carbon-based nano particles with strong optical absorption have been developed, their clearance, potential cytotoxicity, and long-term safety issues remain unresolved. Here, we show that 'generally regarded as safe (GRAS)' melanoidins prepared from glucose and amino acid offer a high light-to heat conversion efficiency, biocompatibility, biodegradability, nonmutagenicity, and efficient renal clearance, as well as a low cost for synthesis. We exhibit a wide range of biomedical photonic applications of melanoidins, including in vivo photoacoustic mapping of sentinel lymph nodes, photoacoustic tracking of gastrointestinal tracts, photothermal cancer therapy, and photothermal lipolysis. The biodegradation rate and renal clearance of melanoidins are controllable by design. Our results confirm the feasibility of biodegradable melanoidins for various photonic applications to theranostic nanomedicines.</P>

In vitro photoacoustic measurement of hemoglobin oxygen saturation using a single pulsed broadband supercontinuum laser source

Lee, Changho,Jeon, Mansik,Jeon, Min Yong,Kim, Jeehyun,Kim, Chulhong The Optical Society 2014 Applied Optics Vol.53 No.18

<P>We have utilized a single pulsed broadband supercontinuum laser source to photoacoustically sense total hemoglobin concentration (HbT) and oxygen saturation of hemoglobin (SO2) in bloods in vitro. Unlike existing expensive and bulky laser systems typically used for functional photoacoustic imaging (PAI), our laser system is relatively cost-effective and compact. Instead of using two single wavelengths, two wavelength bands were applied to distinguish the concentrations of two different chromophores in the mixture. In addition, we have successfully extracted the total dye concentration and the ratio of the red dye concentration to the total dye concentration in mixed red and blue dye solutions in phantoms. The results indicate that PAI with a cheap and compact fiber based laser source can potentially provide HbT and SO2 in live animals in vivo.</P>