The development of high specific surface area and mesoporous activated carbons is required to improve the electrochemical performance of EDLC. In this study, kenaf-derived activated carbons (PK-AC) were prepared for high-power-density EDLC via phosphoric acid stabilization and steam activation. The pyrolysis behavior of kenaf with respect to the phosphoric acid stabilization conditions were examined via TGA and DTG. The textural properties of PK-AC were studied with N2/ 77 K adsorption–desorption isotherms. In addition, the crystalline structure of PK-AC was observed via X-ray diffraction. The specific surface area and mesopore volume ratio of PK-AC were determined to be 1570–2400 m2/ g and 7.7–44.5%, respectively. In addition, PK-AC was observed to have a high specific surface area and mesopore volume ratio than commercial coconut-derived activated carbon (YP-50F). The specific capacitance of PK-AC was increased from 77.0–99.5 F/g (at 0.1 A/g) to 49.3–88.9 F/g (at 10.0 A/g) with activation time increased. In particular, K-P-15-H-9–10 observed an approximately 35% improvement in specific capacitance at a higher current density of 10.0 A/g compared to YP-50F. As a result, the phosphoric acid stabilization method was confirmed to be an efficient process for the preparation of high specific surface area and mesoporous biomass-derived activated carbons, and the kenaf-derived activated carbons prepared by this process have great potential for application as electrode active materials in high-power EDLC.

Marine biomass (MB) offers an environmentally friendly and readily available carbon source from the ocean. However, the high concentration of alkali and alkaline earth metals (AAEMs) in MB typically reduces the carbon yield and inhibits micropore formation during heat treatment due to catalytic gasification. In this study, we successfully synthesized activated carbon (AC) with a high specific surface area (> 1,500 m2/ g) and significant mesopore content (60%, mean pore size: 3.4 nm) from MB by employing preheating, controlled acid purification, and CO₂ activation. The formation of mesopores in the MB-derived AC was driven by catalytic gasification induced by intrinsic and residual AAEMs during preheating and physical activation processes. We evaluated the potential of the MB-derived AC as an electrode material for electric doublelayer capacitors (EDLCs). The material demonstrated high specific capacitance values of 25.9 F/g and 29.4 F/g at 2.7 V and 3.3 V, respectively, during charge–discharge cycles. These high capacitance values at elevated voltages were attributed to the increased number of solvated ions (e.g., 1.93 mmol/g at 3.3 V) present in the mesopores. Fluorine-19 nuclear magnetic resonance (19F solid-state NMR) analysis revealed a substantial increase in solvated ion concentration within the mesopores of the MB-derived AC electrode at 3.3 V, demonstrating enhanced ion mobility and diffusion. These findings highlight the potential of MB-derived AC as a promising electrode material for high-voltage energy storage applications.

최근 이중설강(double listing) 제도의 도입이 일부 대학에서 추진되거나 논의 되는 가운데 본 연구는 이를 교양교육의 관점에서 고찰하고 주요 쟁점을 분석하 는 데 목적이 있다. 이는 학사 운영의 유연성 제고와 전공 탐색 기회 확대를 위 한 방안으로 활용되고 있으나, 교양교육 고유의 취지와 방법론에 비추어 신중한 검토가 요구된다. 본 연구는 관련 문헌 고찰과 국내 대학 사례를 분석하고 이를 바탕으로 이중설강제도의 주요 쟁점을 도출하였다. 이중설강제도는 학문 간 경계 를 완화하고 학생의 전공 탐색을 촉진하는 등의 목적이 있는 동시에, 교양교육의 본래 취지와 학문적 기반을 약화시킬 우려도 있다는 점에서 그 운영에 있어 명 확한 원칙이 요구된다. 본 연구는 이중설강제도의 교육적 쟁점을 비판적으로 고 찰함으로써 대학 교양교육의 본질과 정체성을 유지하면서 교육과정 운영의 실효 성을 확보할 수 있는 이론적 기반과 제도 설계 방향에 대한 논의를 더욱 활성화 하는 데 기여할 수 있을 것이다.

Due to the excessive academic burden on Chinese primary and secondary school students, problems such as myopia, depression, and sleep deprivation have emerged. Additionally, extracurricular tutoring has hindered the development of school education and exacerbated educational inequality. As a result, China implemented the “Double Reduction” policy during the compulsory education stage to alleviate students’ homework load and reduce the burden of extracurricular tutoring, which has sparked a wave of research among scholars. This study uses China National Knowledge Infrastructure (CNKI) as the database and retrieves papers related to the Double Reduction policy published between 2013 and 2024, with a total of 886 valid documents after screening. CiteSpace software is used to analyze the selected literature. The study finds that the annual research trend on the Double Reduction policy initially shows a fluctuating increase followed by a decrease, which is primarily influenced by the policy's introduction. Furthermore, the research collaboration network is relatively sparse, with few cooperative relationships between researchers and institutions. Lastly, the research hotspots of the Double Reduction policy encompass four main areas: implementation and fundamental education reform; academic burden and classroom teaching reform; school education, family education, and societal collaboration in education; and the development of physical education and holistic education. The research trends include initial explorations of burden reduction measures, construction of policy support systems, agenda-setting studies on the Double Reduction policy, and evaluation of policy implementation and effectiveness. This study aims to provide a basis for future policy re-decision-making and policy evaluation research.

본 연구의 목적은 복층 배수성·저소음 아스팔트 포장의 공용수명 예측과 경제성 분석에 있다. 성능평가를 위한 현장시 험은 투수시험 및 소음 측정을 실시하였으며, 실내시험은 반사균열, 동탄성계수, 소성변형(FN) 시험을 진행하였다. 성능 평가 결과를 기반으로 포장설계 수명 예측 및 비용 편익 분석을 수행하였으며, 이를 일반 밀입도 포장의 비용 편익과 비 교·분석하여 복층 배수성·저소음 아스팔트 포장의 경제성을 확인하고자 하였다. 성능평가 결과 복층 배수성·저소음 포장 이 일반 밀입도 포장과 비교 시 소음 저감 성능에서 매우 우수한 결과를 나타내었다. 비용 편익 분석 결과 복층 배수성· 저소음 아스팔트 포장은 높은 초기비용에도 불구하고 설계기간동안 낮은 유지보수 비용을 가지며 안전 및 소음 측면에 서 일반 밀입도 포장과 비교 시 매우 경제적인 것으로 나타났다. 총 비용과 총 편익 비용을 편익 비용 비율(BCR)로 계 산한 결과 복층 배수성·저소음 아스팔트 포장이 단위 비용 당 편익 측면에서 방음벽이 있는 다른 포장에 비해 가장 우수 한 결과를 보였다.

본 연구의 목적은 아버지의 일-가정 양립 이점이 자녀의 학교 적응 에 미치는 영향을 분석하고, 양육 스트레스와 자녀의 행복감이 이중 매 개 역할을 확인하고자 하였다. 연구방법은 육아정책연구소의 한국아동 패널14차년도(2021년) 자료의 아버지와 자녀 1,137쌍 데이터를 활용하였 다. SPSS Macro와 부트스트래핑으로 이중매개모형을 4단계 회귀분석 을 통해 분석하였다. 분석결과는 아버지의 일-가정 양립 이점이 양육스 트레스와 자녀의 행복감을 거쳐 학교적응에 미치는 간접경로인 이중매 개효과가 유의하였다. 그리고 아버지의 일-가정 양립 이점이 학교적응에 직접적으로 영향을 미치는 효과가 유의미하였다. 따라서 일-가정 양립 을 위한 환경을 개선함으로써 아버지의 역할을 강화하고 자녀의 행복 감과 학교 적응 능력을 향상시킬 수 있도록 정책적 제언을 하였다.

The heat transfer characteristics of double-pipe spiral heat exchanger using aluminum oxide nano-fluid were investigated by three different sizes of curvature size, experimentally. Five concentration of nano-fluid as working fluid were made and tested to analyze the heat transfer characteristics. As results, the heat transfer performance was improved at 0.25% of nano-fluid due to high thermal conductivity, however, as the concentration of nanofluid increased (~2.0%), the heat transfer performance deteriorated due to the increase in thermal resistance caused by the sedimentation of particles in the flow path. In addition, the nano-fluid has a higher pressure drop than water due to its high density and viscosity. The optimal range for heat transfer enhancement of nano-fluid was found to be less than 4.0 LPM in flow rate and 0.25% of nano-fluid concentration in this study.