본 연구의 목적은 실패두려움과 인지된 경기력의 관계에서 경쟁상태불안과 자기효능감의 이중 매개효과를 분석하고 각 변인 간의 인과관계를 탐색하는 것이다. 이를 위하여 서울·경기도 소재 중학생 축 구선수 326명을 대상으로 자기보고식 설문을 진행하였다. 수집된 자료는 SPSS 28.0과 Amos 28.0 프로그 램을 이용하여 구조방정식모델분석과 매개효과를 검증하였고 매개변인의 간접효과 유의성을 확인하기 위 해서 부트스트래핑 검증을 실시하였다. 그 결과 첫째, 실패두려움이 경쟁상태불안과 자기효능감에 유의한 영향을 미치는 것으로 나타났다. 둘째, 자기효능감이 인지된 경기력에 유의한 영향을 미치는 것으로 나타 났다. 셋째, 실패두려움과 인지된 경기력의 관계에서 자기효능감의 완전매개효과를 확인하였다. 본 연구를 통해 청소년 축구선수의 실패두려움이 경쟁상태불안과 자기효능감에 영향을 주는 변인임을 확인하였으며, 자기효능감이 인지된 경기력을 위한 중요 매개변수임을 확인하였다. 청소년 선수들이 안정적인 심리상태로 선수생활을 영위하기 위해 실패두려움의 강도를 낮추고 자기효능감을 향상시키는 것은 중요하며, 지도자들 의 독려와 새로운 방향의 전략이 필요할 것이다.

This study was performed to evaluate the pollutants removal characteristics of two types of RBFs(Riverbank filtration, Riverbed filtration) intake facilities installed in Nakdong River and in Hwang River respectively. The capacity of each RBF is 45,000 ㎥/d for riverbank filtration intake facility and 3,500 ㎥/d for riverbed filtration intake facility. According to data collected in the riverbank filtration site, removal rate of each pollutant was about BOD(Biochemical oxygen demand) 52%, TOC(Total organic carbon) 57%, SS(Suspended solids) 44%, Total coliforms 99% correspondingly. Furthermore, Microcystins(-LR,-YR,-RR) were not found in riverbank filtered water compared to surface water in Nakdong River. DOC(Dissolved organic carbon) and Humics which are precursors of disinfection byproduct were also reported to be removed about 59% for DOC, 65% for Humics. Based on data analysis in riverbed filtration site in Hwang River, removal rate of each contaminant reaches to BOD 33.3%, TOC 38.5%, SS 38.9%, DOC 22.2%, UV254 21.2%, Total coliforms 73.8% respectively. Additionally, microplastics were also inspected that there was no obvious removal rate in riverbed filtered water compared to surface water in Hwang River.

Li1.3Al0.3Ti1.7(PO4)3(LATP) is considered a promising material for all-solid-state lithium batteries owing to its high moisture stability, wide potential window (~6 V), and relatively high ion conductivity (10-3–10-4 S/cm). Solid electrolytes based on LATP are manufactured via sintering, using LATP powder as the starting material. The properties of the starting materials depend on the synthesis conditions, which affect the microstructure and ionic conductivity of the solid electrolytes. In this study, we synthesize the LATP powder using sol-gel and co-precipitation methods and characterize the physical properties of powder, such as size, shape, and crystallinity. In addition, we have prepared a disc-shaped LATP solid electrolyte using LATP powder as the starting material. In addition, X-ray diffraction, scanning electron microscopy, and electrochemical impedance spectroscopic measurements are conducted to analyze the grain size, microstructures, and ion conduction properties. These results indicate that the synthesis conditions of the powder are a crucial factor in creating microstructures and affecting the conduction properties of lithium ions in solid electrolytes.

PURPOSES : When fire event occurs in tunnel the reinforced concrete is exposed to very high temperature at a very short time period. This study investigates the tensile behavior of steel rebar that experienced high temperature. METHODS : The steel rebar was exposed to 200, 400, 600, and 800℃ following the ISO 834 temperature-time fire curve. Hightemperature- exposed steel rebars were tested using the UTM for their yielding and tensile strengths, and elongation rate. RESULTS : Up to an exposure temperature of 600℃, the tensile properties of the rebar did not vary considerably. However, at 800℃ (which corresponds to a temperature rise time of approximately 22 min), the rebar lost its yielding and tensile strength by approximately 27 and 13%, respectively, compared to the control specimen. Further, the elongation rate increased after exposure to 600℃. The above fundamental tensile test results can be a good reference for future guidelines in the repair manual for tunnels after severe fire events. CONCLUSIONS : When steel rebar experiences high temperatures of 800℃, the yield strength of the rebar reduces approximately 27%. This strength reduction can cause severe structural damage to tunnels that use reinforced concrete as the primary structural elements.

Carbon fibers (CFs) are considered promising composite materials for various applications. However, the high cost of CFs (as much as $26 per kg) limits their practical use in the automobile and energy industries. In this study, we developed a continuous stabilization process for manufacturing low-cost CFs. We employed a textile-grade polyacrylonitrile (PAN) fiber as a low-cost precursor and UV irradiation technique to shorten the thermal stabilization time. We confirmed that UV irradiation on the textile-grade PAN fibers could lower the initial thermal stabilization temperature and also lead to a higher reaction. These resulted in a shorter overall stabilization time and enhancement of the tensile properties of textilegrade PAN-based CFs. Our study found that only 70 min of stabilization time with UV irradiation was required to prepare textile-grade PAN-based low-cost CFs with a tensile strength of 2.37 ± 0.22GPa and tensile modulus of 249 ± 5 GPa.

In this study, multilayered SnO nanoparticles are prepared using oleylamine as a surfactant at 165oC. The physical and chemical properties of the multilayered SnO nanoparticles are determined by transmission electron microscopy (TEM), scanning electron microscopy (SEM), energy-dispersive spectroscopy (EDS), X-ray diffraction (XRD), and X-ray photoelectron spectroscopy (XPS). Interestingly, when the multilayered SnO nanoparticles are heated at 400oC under argon for 2 h, they become more efficient anode materials, maintaining their morphology. Heat treatment of the multilayered SnO nanoparticles results in enhanced discharge capacities of up to 584 mAh/g in 70 cycles and cycle stability. These materials exhibit better coulombic efficiencies. Therefore, we believe that the heat treatment of multilayered SnO nanoparticles is a suitable approach to enable their application as anode materials for lithium-ion batteries.

본 연구는 서울·경기 소재 65세 이상 노인 463명을 대상으로 신체활동 참여에 따른 체력요 인과 인지기능, 일상생활수행능력, 도구적 일상생활수행능력 및 심리적 변인에 대한 차이를 분석하였다. 수집 된 자료는 SPSS 25.0 통계프로그램을 이용하여 빈도분석, 신뢰도 분석, 독립 t-검증과 일원분산분 석 그리고 피어슨의 상관관계분석을 실시하였으며 모든 통계적 유의수준은 p<.05로 설정하였다. 그 결과 첫째, 노인의 신체활동 참여유무에 따라 체력, 인지기능, 일상생활수행능력, 도구적일상생활수행능력 및 심리적 변인인 우울과 삶의 질에 통계적으로 유의한 차이가 나타났으며, 신체활동에 참여하는 노인의 참여빈도에 따라 체력, 인지기능, ADL, IADL, 우울 및 삶의 질에 통계적 유의한 차이가 나타났다. 신체활동에 참여하는 노인의 참여시간에 따라 체력에서 통계적 유의한 차이가 나타났다. 둘째, 체력과 인지기능, ADL, IADL, 우울 및 삶의 질의 상관관계를 살펴본 결과 대부분의 요인에서 상관관계가 나타났다. 이러한 연구결과를 바탕으로 노인의 성공적인 노화와 자립적인 노후생활을 위해 신체활동을 포함한 체계적인 중재 전략의 개발이 필요하다.