• 치위생과학회지
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• 제21권3호
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• pp.133-139
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• 2021

Background: Smoking in adolescence leads to an intensified addiction to nicotine when physical and mental growth has not yet been completed. With the advent of e-cigarettes, the rate of e-cigarette use among Korean adolescents has been steadily increasing. To date, studies on e-cigarettes and oral health, especially on the relationship between smoking styles and oral health in adolescents, are limited. Therefore, this study aimed to identify the risk factors for oral health problems caused by the repeated use of conventional cigarettes and e-cigarettes. Methods: This explanatory research study compared the adolescents' experiences of periodontal disease symptoms according to smoking type through a secondary analysis of the original data from the 15th Adolescent Health Behavior Survey (2019). Cross-analysis was performed to compare the smoking patterns according to the adolescents' general characteristics. Finally, a binary logistic regression analysis was performed to determine how smoking characteristics affect the adolescents' experience of periodontal disease symptoms. Results: In terms of patients' general characteristics, significant differences were observed in sex, school level, grades, household economic status, type of residence, and father's education level between adolescents who smoked conventional cigarettes alone and those who smoked both conventional cigarettes and e-cigarettes (p<0.05). After checking the factors affecting the smoking pattern and the experience of periodontal disease symptoms in adolescents, it was found that the duplicate smoking group was more likely to experience periodontal disease symptoms (odds ratio, 1.20) than the group that smoked conventional cigarettes alone (p<0.05). Conclusion: Duplicate smokers experienced more symptoms of periodontal disease than those who smoked cigarettes alone. Based on the findings of this study, smoking cessation counseling according to the smoking type and differentiated education for oral health promotion should be provided.

• 한국분말재료학회지
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• 제26권1호
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• pp.1-5
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• 2019

In this study, porous Mo-5 wt% Cu with unidirectionally aligned pores is prepared by freeze drying of camphene slurry with $MoO_3-CuO$ powders. Unidirectional freezing of camphene slurry with dispersion stability is conducted at $-25^{\circ}C$, and pores in the frozen specimens are generated by sublimation of the camphene crystals. The green bodies are hydrogen-reduced at $750^{\circ}C$ and sintered at $1000^{\circ}C$ for 1 h. X-ray diffraction analysis reveals that $MoO_3-CuO$ composite powders are completely converted to a Mo-and-Cu phase without any reaction phases by hydrogen reduction. The sintered bodies with the Mo-Cu phase show large and aligned parallel pores to the camphene growth direction as well as small pores in the internal walls of large pores. The pore size and porosity decrease with increasing composite powder content from 5 to 10 vol%. The change of pore characteristics is explained by the degree of powder rearrangement in slurry and the accumulation behavior of powders in the interdendritic spaces of solidified camphene.

• 한국의류산업학회지
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• 제21권4호
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• pp.432-451
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• 2019

Companies and brands that practice sustainability pay attention to New Media due to its ability to build a sustainable relationship between companies and consumers. The need for research on specific roles, characteristics, and social media effects on eco-friendly advertising has had rapid growth in marketing programs for sustainable activities especially shown through social media. Information about sustainable fashion has spread to consumers through social media, and multifarious efforts have been made to attract the attention of youth. Despite the dramatic increase in eco-friendly marketing through social media as a part of sustainability, there is a lack of research on the major influences of emotional factors such as ad color and expression in social media. In this context, it is meaningful to identify relationships between emotional responses, advertising value and consumer behavior of sustainable fashion brands in Instagram and implement a suitable advertising type (color vs expression) for consumers. We used 366 responses for the final analysis. Data were analyzed by factor analysis, structural equation modeling using SPSS 18.0 and AMOS 18.0. The results of this study suggest that emotional responses, advertising value have a significant effect on the flow. This study expands on a previously limited research field by verifying consumer responses to image advertising on Instagram, rather than general sustainable fashion marketing. The study results also provide meaningful implications for a relation formation between customers and fashion brands vis-${\grave{a}}$-vis sustainable social media marketing.

• 한국표면공학회지
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• 제52권3호
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• pp.138-144
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• 2019

In this work, PEO (Plasma Electrolytic Oxidation) film formation behavior of Al6061 alloy was investigated as a function of applied current density of AC at 310 Hz in the range from $120mA/cm^2$ to $300mA/cm^2$ in 0.5 M $Na_2SiO_3$ solution. When applied current density is lower than a critical voltage of about $132mA/cm^2$, voltage reaches a steady-state values less than 120 V without generation of arcs and metallic color of the alloy surface remains. On the other hand, when applied current density exceeds about $132mA/cm^2$, voltage increases continuously with time and arcs are generated at more than 175 V, resulting in the formation of PEO films with grey colors. Two different types of arcs, large size and small number of arcs with orange color, and small size and large number of arcs with white color, were generated at the same time when the PEO film thickness exceeds about $50{\mu}m$, irrespective of applied current density. Formation efficiency of the PEO films was found to increase with increasing applied current density and the growth rate was obtained to be about $5{\mu}m/min$ at $300mA/cm^2$. It was also found that surface roughness of the PEO films with $70{\mu}m$ thickness is not dependent on the applied current density.

• 대한화장품학회지
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• 제44권4호
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• pp.419-425
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• 2018

본 연구에서는 가교 분자를 사용하여 0.7 kPa에서 17.7 kPa까지 다양한 강도를 갖는 콜라겐 겔을 성공적으로 제조하였다. 가교된 콜라겐 겔에 다공성 기공을 도입하고 진피세포를 내부에 담지하여, 겔 강도에 따른 세포 성장 및 거동을 확인하였다. 상대적으로 강도가 높은 겔에서 진피세포의 프로콜라겐 생합성이 47 ng에서 32 ng까지 감소하는 것을 확인하였다. 이렇게 제조된 인공피부 진피에 아데노신을 처리하였을 때, 특정 강도를 갖는 콜라겐 겔에서 프로콜라겐 생합성이 감소하는 것을 확인하였다. 반면에 기능성 펩타이드를 처리하였을 때는 프로콜라겐 생합성이 콜라겐 겔의 강도에 크게 영향을 받지 않는 것을 확인할 수 있었다. 이러한 결과는 강도가 제어된 인공피부 제조 및 응용, 나아가 다양한 조직공학 분야의 기반 기술로 활용 가능하리라 기대된다.

• Metals and materials international
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• 제24권6호
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• pp.1394-1402
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• 2018

This study investigates the mechanism of MnS precipitation on $Al_2O_3-SiO_2$ inclusions during the solidification of non-oriented silicon steel, especially the influence of the phase structures and sizes of the oxides on the MnS precipitation, by scanning electron microscopy and transmission electron microscopy coupled with energy dispersive spectrometry. The investigation results show that MnS tends to nucleate on submicron-sized $Al_2O_3-SiO_2$ inclusions formed by interdendritic segregation and that it covers the oxides completely. In addition, MnS can precipitate on micron-sized oxides and its precipitation behavior is governed by the phase structure of the oxides. The MnS embryo formed in a MnO-containing oxide can act as a substrate for MnS precipitation, thus permitting further growth via diffusion of solute atoms from the matrix. MnS also precipitates in a MnO-free oxide by the heterogeneous nucleation mechanism. Furthermore, MnS is less prone to precipitation in the $Al_2O_3$-rich regions of the $Al_2O_3-SiO_2$ inclusions; this can be explained by the high lattice disregistry between MnS and $Al_2O_3$.

• Journal of the Korean Academy of Child and Adolescent Psychiatry
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• 제30권1호
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• pp.34-41
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• 2019

Objectives: We aimed to compare preterm, neurodevelopmentally disordered and healthy full-term children. Methods: We enrolled 47 children who were born preterm, 40 neurodevelopmentally disordered children, and 80 healthy children as control participants, in order to assess the cognitive functioning and the risk of behavioral problems at the age of 5. Children were assessed using the Korean Wechsler Preschool and Primary Scale of Intelligence-4th edition (K-WPPSI-IV), the Child Behavior Checklist (CBCL), and the Temperament and Character Inventory (TCI). Results: The mean K-WPPSI-IV score of the preterm group was $87.19{\pm}17.36$, which was significantly higher than that of the neurodevelopmental disorder group ($69.98{\pm}28.63$; p<0.001) but lower than that of the control group ($107.74{\pm}14.21$; p<0.001). The cumulative CBCL scores of the preterm children were not significantly different from those of the control group. Additionally, the TCI scores for reward dependence of the preterm children were higher than those of the control group. Conclusion: The cognitive performance of preterm infants was lower than that of healthy full-term infants at the age of 5, and there was an association between slower growth and decreased cognitive ability.

• 대한토목학회논문집
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• 제39권1호
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• pp.115-122
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• 2019

강섬유 습식Shotcrete는 굳지 않은 콘크리트를 노즐로부터 소정의 위치에 부착시키는 콘크리트를 시공함으로서 원지반 자체의 전단강도를 증가시켜 품질을 향상시키고 터널의 안정화를 도모한다. 강섬유 습식Shotcrete는 인장 저항능력을 증대시킴으로써 국부적인 균열의 생성 성장을 억제하는 콘크리트의 강도와 역학적 거동 특성을 개선 및 보강한다. 또한, 강섬유 습식Shotcrete는 불연속의 짧은 강섬유를 콘크리트 속에 균등하게 분산시켜 인장강도, 휨강도, 균열에 대한 저항성 등을 개선한 Shotcrete이다. 이 연구에서는 NATM 터널의 숏크리트에 대한 압축강도 시험과 휨강도 시험을 실시하고 숏크리트타설 압력을 900 RPM, 1,000 RPM, 1,100 RPM으로 변화시켜 리바운드 감소율을 측정하였다. 따라서 국내 NATM 터널공사에 적용할 수 있는 자료를 제시하였다.

• Current Photovoltaic Research
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• 제7권3호
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• pp.65-70
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• 2019

As a demand of higher power photovoltaic modules, shingled, multi-busbar, half-cell, and bifacial techniques are developed. Multi-busbar module has advantage for large amount of light havesting. And, half-cell is high power module for reducing resistive losses and higher shade tolerance. Recently, researches on multi-busbar is focused on reliability according to adhesion and intermetallic compound between Sn-Pb solder and Ag electrode. And half-cell module is researched to comparing with full-sized cell module for structure difference. In this study, we investigated the factors affecting to efficiency and adhesion of multi-wires half-cell module according to wire thickness, solder thickness, and flux. The results of solar simulator and peel test was that peel strength and efficiency of soldered cell is not related. But samples with flux including high solid material showed high efficiency. The results of FE-SEM and EDX line scan on cross-section between wire and Ag electrode for different flux showed thickness of solder joint between wire and Ag electrode is increasing through solid material increasing. Flux including high solid material would affect to solder behavior on Ag electrode. Higher solid material occurred lower growth of IMC layer because solder permeate to sider of wire ribbon than Ag electrode. And it increased fill factor for high efficiency. In soldering process, amount of solid material in flux and solder thickness are the factor related with characteristic of soldered photovoltaic cell.

• 한국재료학회지
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• 제29권1호
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• pp.1-6
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• 2019

Recent industrialization has led to a high demand for the use of fossil fuels. Therefore, the need for producing hydrogen and its utilization is essential for a sustainable society. For an eco-friendly future technology, photoelectrochemical water splitting using solar energy has proven promising amongst many other candidates. With this technique, semiconductors can be used as photocatalysts to generate electrons by light absorption, resulting in the reduction of hydrogen ions. The photocatalysts must be chemically stable, economically inexpensive and be able to utilize a wide range of light. From this perspective, cuprous oxide($Cu_2O$) is a promising p-type semiconductor because of its appropriate band gap. However, a major hindrance to the use of $Cu_2O$ is its instability at the potential in which hydrogen ion is reduced. In this study, gold is used as a bottom electrode during electrodeposition to obtain a preferential growth along the (111) plane of $Cu_2O$ while imperfections of the $Cu_2O$ thin films are removed. This study investigates the photoelectrochemical properties of $Cu_2O$. However, severe photo-induced corrosion impedes the use of $Cu_2O$ as a photoelectrode. Two candidates, $TiO_2$ and $SnO_2$, are selected for the passivation layer on $Cu_2O$ by by considering the Pourbaix-diagram. $TiO_2$ and $SnO_2$ passivation layers are deposited by atomic layer deposition(ALD) and a sputtering process, respectively. The investigation of the photoelectrochemical properties confirmed that $SnO_2$ is a good passivation layer for $Cu_2O$.