Earticle

나노기술이 발전함에 따라 나노물질의 사용량이 증가하고, 그에 따른 환경 및 인체 유해성 문제가 사회적 이슈로 대두되고 있으나 나노물질에 대한 규제나 법규는 아직 제정되어 있지 않다. 이에 본 연구에서는 WPMN에서 지정한 제조나노물질 13종 중 국내에서 가장 많이 사용되고 있는 물질인 aluminium oxide의 거동평가를 실시하여 연구활동종사자들을 위한 안전지침의 기초 자료로 활용하고자 하였다. 실험은 실제 연구실을 1/6의 크기로 축소하여 제작한 chamber에서 진행되며, NIOSH method 0500에 준하여 질량농도를 측정하였다. 연구 결과 질량 농도는 물질의 입자 크기에 반비례하는 것으로 나타났으며, 환기 설비의 작동만으로 질량농도가 약 1/8배까지 감소하는 것을 확인 할 수 있었다. 본 연구를 향후 나노물질 관련 연구활동종사자를 위한 안전지침의 기초자료로 활용할 수 있을 것으로 보이나, 연구의 신뢰도를 높이기 위해 입경에 따른 질량농도, 수농도 측정등의 실험이 필요할 것으로 사료된다.

With the development of nanotechnology, the amount of nanomaterials increases and the problems of environment and the toxic property associated with it have become a social problem. But regulations and laws of nanomaterials have not yet been established. The purpose of this study is to utilize as the database of safety guidelines for research activities’ workers associated with nanomaterials to conduct a behavior evaluation of aluminium oxide, which is most widely used in thirteen kinds of WPMN manufactured nanomaterials in the country. The experiment proceeds in the chamber reduced to 1/6 size of the actual laboratory, the test method was performed in NIOSH 0500. As the results of the study, the mass concentration was in inverse proportion to the particle size of the nanomaterials. And the mass concentration during the operation of ventilation equipment was reduced to about 1/8 times. In the future, it can be utilized as the database of safety guidelines for research activities’ workers associated with nanomaterials. However, in order to increase the reliability of the study, the experiment of the mass concentration by particle size and Condensation Particle Counters will be needed additionally.

This syudy analyzed the main bodies, marginal space, Position of the main bodies of current textbooks in high schools and "the eriteria of reading system for textbooks" which was suggested the Department of Education and Provided some suggestions for the improvement. The research methods used for the study were both literature review and survey rdsdarch with a questionaire. Inorder to research for the main body of textbook, space of margin, the optimum position of the main body, sizes of litters, spaces between letters, words, lines, length of lines, sizes of main body and margin, and margin and position of main body were checked through a related literature review. For the questionaire experiment, a questionaire based on data drawn from analysis of current textbooks, :criteria for reading system of textbook" suggested by the Department of Education, and some suggestions for improvement by the researcher was made and used for the test, targetting 384 body and girl student in high schools.n high schools.

본 연구는 대형병원 환자쏠림현상 완화에 도움이 되는 소비자의 친사회적 행동 제고를 위한 효과적인 메시지 전략을 탐색하는데 목적이 있었다. 구체적으로 합병증이 없는 고혈압, 당뇨와 같은 만성질환이 나 감기 등 가벼운 질환의 경우 대형병원 대신 동네병의원 이용에 따른 편익 소구의 영향을 해석수준 이론과 조절초점이론을 바탕으로 살펴보고자 하였다. 주요 발견 사항은 다음과 같다. 첫째, 만성질환이 나 가벼운 질환의 경우 대형병원 대신 동네병의원 이용을 이용함으로써 환자나 보호자가 받을 수 있 는 개인적 편익 중심의 소구가 공동체 전체가 누릴 수 있는 사회적 편익 중심의 소구보다 동네병의원 이용의도에 더 효과적인 것으로 나타났다. 둘째, 편익과 해석수준 간의 상호작용효과는 유의하게 나타 났다. 사회적 편익은 추상적 메시지로 소구할 때, 개인적 편익은 구체적 메시지로 소구할 때 동네병의 원 이용의도가 더 높게 나타났다. 마지막으로 편익과 해석수준, 조절초점 간의 삼원상호작용효과는 통 계적으로 유의하지 않았다. 사회적 편익 소구는 추상적·촉진초점의 메시지가 효과적인 것으로 나타났 고, 개인적 편익 소구는 구체적·예방초점 메시지가 상대적으로 높게 나타났지만, 통계적으로 유의한 차 이는 없는 것으로 나타났다.

The present study explored effective message strategies to enhance prosocial behavior of consumers that helps reduce the concentration of patients in large hospitals. Specifically, in the case of chronic or mild diseases, the effect of the benefits appeal, construal level, and regulatory focus interplay to behavioral intention on using local hospitals instead of large hospitals was examined. As a result of the analysis, as for behavioral intention of local hospitals instead of large hospitals, the personal benefits appeal is more effective than the social benefits appeal. Next, the interaction effect of benefits appeal and construal level was statistically significant. For social benefits appeal, more persuaded by a abstract message frame, whereas for personal benefits appeal, more persuaded by a concrete message frame. Last, the interaction effect among benefits appeal, construal level, and regulatory focus was not statistically significant. Social benefits appeal showed that higher behavioral intention for abstract and promotion focused message. Meanwhile, for the personal benefits appeal, concrete and prevention focused message was relatively higher than the others, but there was no statistically significant difference.

Purpose: Because of the COVID-19 pandemic in 2020, colleges had no choice but to introduce online classes without sufficient preparation. As a result, various problems emerged in college students’ learning experience. To establish a strategy for improving online education quality, the necessity to understand university students’ learning behavior, learner characteristics, learning satisfaction, and the impact of professor-student interaction on online lecture concentricity. Methods: This study is a cross-sectional survey conducted on college students from nine universities who experienced online lectures in the first semester of 2020. Online lecture learning behavior, learner characteristics, learning satisfaction, and professor-student interaction were analyzed using t-test, ANOVA, and Pearson’s correlation coefficient to explore the difference in online lecture concentration. Results: The concentration in-class lectures and online lectures averaged 7.04 and 5.73, respectively. According to the analysis, online learning concentration was a significant positive correlation by learner characteristics (r=.40, p<.001), professor-student interaction (r=.30, p<.001), online lecture evaluation (r=.34, p<.001). Conclusion: Therefore, it is suggested that universities should establish guidance strategies related to lecture time zones, measures for managing and supervising learners, reflecting online lecture evaluation results, and strategies for improving student interaction.

실제 광산 현장에서 적재된 광석으로부터 미생물에 의한 중금속 용출 가능성을 알아보고자 호산성 미생물인 Acidithiobacillus ferrooxidans와 Acidithiobacillus thiooxidans를 이용하여 초기 산성조건에서 복합금속광(Pb-Zn-As 광석)을 대상으로 60일에 걸쳐 중금속 용출실험을 진행하였다. 용출 시험 초기에는 초기 산성 조건에 의해 용출되는 소량의 중금속 이외에 미생물의 활성화로 인한 중금속의용출은 거의 검출되지 않았다. 그러나 A. thiooxidans이 시료의 환경에 적응한 20일 이후, 중금속 용출량이 급격히 증가하였으며, 독성 물질로 위험성이 높은 비소와 철, 아연이 각각 최대 2800 mg/L, 3700 mg/L, 그리고 2050 mg/L로 용출되는 것을 확인하였다. 반면 A. ferrooxidans을 주입한 반응기와 미생물을 주입하지 않은 대조실험 결과에서는 약간의 아연을 제외한 기타 중금속 용출이 전혀 발생하지않았다. 이를 통해 산성조건의 광산 현장에서 토착 미생물에 의한 황화광 산화 및 중금속의 용출 가능성을 확인할 수 있었고, 본 연구에 사용된 고농도 비소를 함유한 광석 시스템에서는 A. ferrooxidans 보다 A. thiooxidans에 의한 중금속 용출이 더욱 위협적이라는 것을 확인하였다.

To investigate the potential for leaching of heavy metals by bacteria from ores stacked on actual mining sites, leaching tests of a complex metallic ore (Pb-Zn-As ore) were conducted over 60 days using acidophile bacteria Acidithiobacillus ferrooxidans and Acidithiobacillus thiooxidans under initial acidic conditions. Initially, a small amount of heavy metals was leached due to the initial acidic conditions. After 20 days, when A. thiooxidans in the reactor was adapted to the ore, the amount of leached heavy metals rapidly increased; the concentrations of leached arsenic, iron, and zinc reached a maximum of 2800, 3700, and 2500 mg/L, respectively. On the other hand, in the presence of A. ferrooxidans or in the control test without bacteria, heavy metals, except zinc, were barely detected in leaching. Through this study, it was confirmed that (i) bacteria could leach heavy metals at mining sites under acidic conditions and (ii) leaching of heavy metals from a high arsenic-containing ore by A. thiooxidans was more significant than that by A. ferrooxidans.

본 연구에서는 탄산나트륨(Na2CO3)을 사용하여 염배소한 함바나듐 티탄철광(VTM)으로부터 바나듐의 수침출 거동을 고찰하였다. 자력선별 된 정광과 Na2CO3를 질량비 4:1로 혼합한 후 1050 °C, 3시간 조건에서 염배소하고 로드밀을 사용해 D50=48.79 μm로 분쇄하여연구에 사용하였으며 침출 온도와 광액 농도를 수침출 영향인자로 선정하였다. 연구 결과, 온도가 25, 55, 85 °C로 증가할수록 바나듐의침출율은 90.4, 88.2, 83.8%로 감소하였으며 광액 농도 10, 50, 100 w/v%에 따른 바나듐 침출율은 각각 90.4, 87.0, 87.0%로 변화가 크지않았다. 이를 바탕으로 25 °C, 100 w/v%, 300 rpm, 1시간의 조건에서 다단 침출을 수행한 결과, 총 4단 침출 후 최종 침출액의 바나듐 농도는 16.20 g/L로 분석되었다. 따라서 다단 침출을 통해 고농도 소듐바나데이트 용액의 제조가 가능하였다.

This study investigated the water leaching behavior of vanadium in Na2CO3-roasted vanadium-bearing titaniferous magnetite (VTM) concentrate. The magnetic concentrate and Na2CO3, mixed in a mass ratio of 4:1, were roasted at 1050 °C, kept for 3 h, and ground to a size of D50 = 48.79 μm using a rod mill. The effects of leaching temperature and pulp density on water leaching were then investigated. The results show that the vanadium leaching efficiency decreased to 90.4%, 88.2%, and 83.8% as the temperature increased to 25, 55, and 85 °C, respectively, whereas it remained almost constant 90.4%, 87.0%, and 87.0% as the pulp density increased to 10, 50, and 100 w/v%, respectively. Based on the preliminary leaching results, multi-stage leaching was conducted with the experimental conditions of 25 °C, 100 w/v%, 300 rpm, and 1 h. The vanadium concentration in the final leaching solution was determined as 16.20 g/L after four stages of leaching. Thus, a high-concentration sodium vanadate solution was prepared by multi-stage leaching.

This study investigated the effects of neurofeedback training on concentration in children with attention deficit/ hyperactivity disorder (ADHD). A single-subject ABA' experimental design was used to determine the effects of neurofeedback training. The participants of the study were three boys with ADHD. In the intervention phase after the baseline assessment, participant 1 and 3 trained neurofeedback for twelve sessions, and participant 2 trained ten times. The EEG was recorded during each session and was analyzed for relative power spectrum by beta/theta ratio. The concentration behaviors were measured on a 10-second interval scale during 15 minutes. The concentration was assessed using Auditory Continuous Performance Test (ACPT), and the ADHD symptoms were assessed by the Conners Teacher Rating Scale-Revised (CTRS-R) in pre and posttest. The data were visually analyzed using graphs and descriptive statistical analysis. The results of the study suggest that, after the neurofeedback training sessions, the participants showed a significant increase in their concentration behaviors. The scores of ACPT and CRTS-R were improved as well. However, no significant EEG change was observed, and no correlation of EEG with concentration behaviors was established.

발달적으로 중요한 시기인 초등학생의 과제 집중 시에 나타나는 디지털 펜 기반 행동 지표는 학습자의 몰입 정도를 평가하고 이를 증진시키기 위한 교육 활동을 설계하는 데 중요한 단서를 제공할 수 있다. 본 연구는 초등학교 1학년부터 6학년까지의 학생 3,779명을 대상으로, 태블릿에서 수행한 만다라 색칠 과제 중 디지털 펜으로 수집된 그리기 행동 데이터를 분석하여 아동의 과제 집중 양상을 정량화하고자 하였다. 이를 위해 선 그린 시간, 선의 획수, 캔버스 채움 비율, 사용한 색의 수 네 가지 지표를 사용하여 K-means 군집 분석을 실시하고, 세 가지 집중 양상 군집을 도출하였으며, 추가적으로 선 속도 및 변화량, 필압 및 변화량, 선 길이 및 변화량 등의 지표를 학년 내에서 정규화하여 군집 간 행동 특성 차이를 검증하였다. 또한, 훈련된 전문가가 각 그림의 집중력을 평정한 그림 집중력 지표와의 대응을 분석한 결과, 세 군집이 각각 낮은, 중간, 높은 집중 수준을 반영하는 행동 패턴으로 해석될 수 있음을 확인하였다. 우리의 결과는 디지털 스타일러스로 측정된 세부 그리기 행동 지표가 특정 과제 수행 시 아동의 집중·몰입 상태를 추정할 수 있는 지표임을 보여주며, 향후 디지털 학습 환경에서 학습자의 몰입 프로파일을 산출하고 개인화된 피드백과 주의력 지원을 제공하는 에듀테크 도구 개발의 기초 자료를 제공하는 것에 의의가 있다.

Behavioral indicators observed during task engagement in elementary school students-who are at a developmentally critical stage-can play an important role in evaluating their level of immersion and designing activities to enhance it. This study analyzed digital stylus data recorded during a table-based mandala coloring task in 3,779 students from 1st to 6th grade to quantify patterns of task-focused engagement. Four drawing indicators (total drawing time, number of strokes, canvas usage ratio, and number of colors used) were standardize dan submitted to K-means clustring, yielding three distinct behavioral clusters. Additional stroke-level features (stroke speed, pressure level, stroke length and their variabilities) were normalized within grade level and compared across clusters using MANOVA and following ANOVAs. Expert ratings based on estabilished art therapy scoring systems were used to derive a Daraing Contentration Index, and its alignment with the three behavioral clusters indicated that they reflected low, intermediate, and high concentration levels, respectively. We demonstrate that our findings demonstrate that fine-grained, stylus-based darawing behavior captured by digital devices can serve as a valid proxy for children's task concentration during authentic learnin-like activities, providing a behaiovral foundation for future edutech tools that generate engagement profiles and deliver personalized feedback and attention support in digital learning environment.

Examining the viscous incompressible bioconvection Casson type nanoliquid flow with Darcy-Forchheimer resistance across a non-linear stretching surface is the primary goal of this study. Non-dimensional variables are used to decrease non-linear expressions. The shooting technique is used to solve the simplified ordinary differential equations. The behavior of several influential parameters is examined graphically and the concentration profile is examined. Thermophoresis parameter, Prandtl number, energy activation, chemical reaction factor, and concentration slip parameter all improve the concentration profile. By contrasting the current findings with earlier published research, the validity of the current study is validated.

Temperature dependence of the critical micelle concentration (CMC), $x_{CMC}$, in micellization can be described by ln $x_{CMC}$ = A + BT + C lnT + D/T, which has been derived statistical-mechanically. Here A, B, C, and D are fitting parameters. The equation fits the CMC data better than conventionally used polynomial equations of temperature. Moreover, it yields the unique(exponent) value of 2 when the CMC is expressed in a power-law form. This finding is quite significant, because it may point to the universality of the thermal behavior of CMC. Hence, in this article, the nature of the equation ln $x_{CMC}$ = A + BT + C lnT + D/T is examined from a lattice-theory point of view through the Flory-Huggins model. It is found that a linear behavior of heat capacity change of micellization is responsible for the CMC equation of temperature.

In the present study, the corrosion behavior of aluminum Al-7075 tempered (T-6 condition) alloy was evaluated by immersion testing and electrochemical testing in 1.75% and 3.5% NaCl environment at acidic, neutral and basic pH. The data obtained by both immersion tests and electrochemical corrosion tests (potentiodynamic polarization and electrochemical impedance spectroscopy tests) present that the corrosion rate of the alloy specimens is minimum for the pH=7 condition of the solution due to the formation of dense and well adherent thin protective oxide layer. Whereas the solutions with acidic and alkaline pH cause shift in the corrosion behavior of aluminum alloy to more active domains aggravated by the constant flux of acidic and alkaline ions (Cl^- and OH^-) in the media which anodically dissolve the Al matrix in comparison to precipitated intermetallic phases (cathodic in nature) formed due to T6 treatment. Consequently, the pitting behavior of the alloy, as observed by cyclic polarization tests, shifts to more active regions when pH of the solutions changes from neutral to alkaline environment due to localized dissolution of the matrix in alkaline environment that ingress by diffusion through the pores in the oxide film. Microscopic analysis also strengthens the results obtained by immersion corrosion testing and electrochemical corrosion testing as the study examines the corrosion behavior of this alloy under a systematic evaluation in marine environment.

Polyvinyl alcohol (PVA)/gelatin hydrogels were prepared by repeating freezing/thawing three times to evaluate the influence of PVA concentration on the strength and the cell growth behavior of the PVA/gelatin hydrogels. The swelling rate of the PVA/gelatin hydrogels decreased with raising the PVA content from 6 wt% to 12 wt% due to the formation of 3-D network inside the hydrogel. No appreciable degradation of the hydrogels was detected. As the PVA content increased from 6 wt% to 12 wt%, the strength of the PVA/gelatin hydrogels increased drastically from 6.4±0.9 kPa to 46.6±9.0 kPa. The PVA/gelatin hydrogels did not show any evidence of causing cell lysis or toxicity, implying that the hydrogels are clinically safe and effective. Although the strength increased with increasing the PVA content, the PVA/gelatin hydrogels containing 8 wt% exhibited the fastest cell growth, which is highly suitable for wound dressing requiring fast healing regeneration.

In this study, we investigated that the resistance switching characteristics of Al-doped MgOx films with increasing Al doping concentration and increasing film thickness. The Al-doped MgOx based ReRAM devices with a TiN/Al-doped MgOx/Pt/Ti/SiO2 were fabricated on Si substrates. The 5 nm, 10 nm, and 15 nm thick Al-doped MgOx films were deposited by reactive dc magnetron co-sputtering at $300^{\circ}C$ and oxygen partial ratio of 60% (Ar: 16 sccm, O2: 24 sccm). Micro-structure of Al-doped MgOx films and atomic concentration were investigated by XRD and XPS, respectively. The Al-doped MgOx films showed set/reset resistance switching behavior at various Al doping concentrations. The process voltage of forming/set is decreased and whereas the initial current level is increased with decreasing thickness of Al-doped MgOx films. Besides, the initial current of Al-doped MgOx films is increased with increasing Al doping concentration in MgOx films. The change of resistance switching behavior depending on doping concentration was discussed in terms of concentration of non-lattice oxygen of Al-doped MgOx.

In this study, we investigated that the resistance switching characteristics of W-doped NbOx films with increasing W doping concentration. The W-doped NbOx based ReRAM devices with a TiN/W-doped NbOx/Pt/Ti/SiO2 were fabricated on Si substrates. The 50 nm thick W-doped NbOx films were deposited by reactive dc magnetron co-sputtering at $400^{\circ}C$ and oxygen partial pressure of 35%. Micro-structure of W-doped NbOx films and atomic concentration were investigated by XRD, TEM and XPS, respectively. The W-doped NbOx films showed set/reset resistance switching behavior at various W doping concentrations. The process voltage of set/reset is decreased and whereas the initial current level is increased with increasing W doping concentration in NbOx films. The change of resistance switching behavior depending on doping concentration was discussed in terms of concentration of metallic tungsten of oxygen of W-doped NbOx.

The objective of this study was to determine effects of temperatures and pH of sodium chloride solution with MgCl₂ ions on corrosion resistance of duplex stainless-steel X2CrNiMoN22-5-3 (DSS) and Ti 6Al 2Nb1Ta1Mo (Ti). Effects of sodium chloride concentration on corrosion resistance were also studied. Corrosion behavior and pitting morphology of duplex stainless steel (DSS) and Ti alloys were evaluated through potentiodynamic polarization, electrochemical impedance spectroscopy (EIS), and scanning electron microscopy (SEM). It was found that a decrease in pH significantly reduced the corrosion resistance of both alloys. Changes in chloride concentration and temperature had more substantial impact on corrosion behavior of DSS than on Ti alloys. Pitting corrosion was formed on DSS samples under all conditions, whereas crevice corrosion was developed on Ti samples with the presence of magnesium chloride at 90 ℃. In conclusion, magnesium chloride ions in an exceedingly strong acidity solution appear to interact with re-passivation process at the surface of these alloys and influence the resulting surface topography.

Two variants of a nanoparticulate titania were investigated for their rheological behavior. These powders were synthesized via a sulfuric acid process, where modification of particular parameters resulted in powders varying in residual sulfate level. It was assumed that residual sulfate would affect the agglomerate structure of suspensions of these powders. These powders were washed with distilled deionized water to remove as much residual soluble sulfate as possible and the supernatant tested for sulfate level and pH. Microstructural and rheological behavior of the powders were examined as a function of number of washes. The rheological yield point was determined to increase with number of washes and in turn increase with decreased residual sulfate level.

The electrochemical corrosion behavior of PCB-Cu under thin liquid film was investigated with varying concentrations of SO₄^2- through polarization curves and electrochemical impedance spectroscopy (EIS). The results indicate that the corrosion process of PCB-Cu was primarily controlled by the reduction of oxygen and the corrosion products. The cathodic current density increased with the concentration improvement of SO₄^2-. Initially, the corrosion rate was dominated by the cathodic reduction process, however, in later stages of corrosion, the accumulation of surface corrosion products inhibited further corrosion of PCB-Cu.

Background: Neuropathic pain is generally defined as a chronic pain state resulting from peripheral and/or central nerve injury. There is a lack of effective treatment for neuropathic pain, which may possibly be related to poor understanding of pathological mechanisms at the molecular level. Curcumin, a therapeutic herbal extract, has shown to be effectively capable of reducing chronic pain induced by peripheral administration of inflammatory agents such as formalin. In this study, we aimed to show the effect of curcumin on pain behavior and serum COX-2 level in a Chronic Constriction Injury (CCI) model of neuropathic pain. Methods: Wistar male rats (150-200 g, n = 8) were divided into three groups: CCI vehicle-treated, sham-operated, and CCI drug-treated group. Curcumin (12.5, 25, 50 mg/kg, IP) was injected 24 h before surgery and continued daily for 7 days post-surgery. Behavioral tests were performed once before and following the days 1, 3, 5, 7 after surgery. The serum COX-2 level was measured on day 7 after the surgery. Results: Curcumin (50 mg/kg) decreased mechanical and cold allodynia (P < 0.001) and produced a decline in serum COX-2 level (P < 0.001). Conclusions: A considerable decline in pain behavior and serum COX-2 levels was seen in rat following administration of curcumin in CCI model of neuropathic pain. High concentration of Curcumin was able to reduce the chronic neuropathic pain induced by CCI model and the serum level of COX-2.