In this work, TiO2 3D nanostructures (TF30) were prepared via a facile wet chemical process using ammonium hexafluorotitanate. The synthesized 3D TiO2 nanostructures exhibited well-defined crystalline and hierarchical structures assembled from TiO2 nanorods with different thicknesses and diameters, which comprised numerous small beads. Moreover, the maximum specific surface area of TiO2 3D nanostructures was observed to be 191 m2g-1, with concentration of F ions on the surface being 2 at%. The TiO2 3D nanostructures were tested as photocatalysts under UV irradiation using Rhodamine B solution in order to determine their photocatalytic performance. The TiO2 3D nanostructures showed a higher photocatalytic activity than that of the other TiO2 samples, which was likely associated with the combined effects of a high crystallinity, unique features of the hierarchical structure, a high specific surface area, and the advantage of adsorbing F ions.

밭농업의 기계작업을 복합기로 일관화하기 위하여 관행의 개별적 기계를 모듈화하고 일체화시켜 둥근두둑 작물의 재배체계에 맞추어 구성하였다. 본 연구의 목적은 둥근두둑 복합작업기의 작업성능을 파악하는데 근거가 되는 슬립의 특성을 분석하여 집약농업의 작업효율을 극대화 할 수 있는 복합작업기의 운용방안을 제시하고자 하였다. 도플러 레이더 속도계를 사용하여 무부하 기준속도를 콘크리트 지면에서 주행속도를 측정하고, 후륜 동반경을 결정함으로써 이론 회전속도를 이용하여 제로슬립 속도를 계산하였다. 연구의 결과는 변수의 유의한 영향에도 불구하고 심하게 낮은 슬립의 범위(3.9-8.9%)에 있음을 보였다. 이는 복합작업기의 무거운 중량에 대응한 정적 후방전도 안정성을 위하여 카테고리 2급 트랙터를 사용하였기 때문이다. 로타베이터를 기본으로 하는 집약농업의 경우 작업속도(2.0-4.0km/h)가 저속이므로‘gear up throttle down’원리가 적용되지 않으며 연료의 소비량은 운용비용에 절대적이지 않을 것으로 판단된다. 따라서 복합기의 운용은 견인 및 연료효율에 맞춰져서는 큰 이득이 예상되지 않으며, 파종상토와 멀칭작업의 품질, 즉 작업결과에 초점이 맞춰져야 한다.

본 연구의 목적은 노인의 삶의 만족도와 주요 변수와의 관계에 관한 연구 모델을 수립하고 분석하여 노인의 삶의 만족도에 영향을 미치는 요인을 탐구하고 사회 복지 정책과 삶의 만족도의 실제적 함의를 제시하는 것이다. 본 연구에서는 삶의 만족도, 자아통합감, 사회적지지 및 노후준비로 구성된 연구 모델을 구축하였다. 이에 따라 자아통합감, 사회적지지가 삶의 만족도에 미치는 영향을 확인하고 노후준비가 이 관계에서 조절변수로 작용하는지 여부를 분석하였다. 또한, 각 변수의 하위 요인 간의 관계를 분석하여 이들 간의 영향 관계를 조사하였다.

Karyotype analysis is a major work in the process of triploid abalone production for the purpose of productivity and quality improvement. However, the metaphase spreads for karyotype analysis have been prepared just from the larvae at trochophore stage, which has restricted the spectrum of sample correction inhibiting more efficient analysis. Here, we investigated the feasibility of preparing metaphase spreads from the larvae at veliger stage that is the next developmental stage of trochophore. For this, diploid and triploid larvae at trochophore and veliger stages from Pacific abalone (Haliotis discus hannai ) were subjected to metaphase spread preparation and its efficiencies were measured and compared each other. As the results, although the efficiencies of metaphase spread preparation were significantly lower in the larvae at veliger stage compared to the ones at trochophore stage regardless of ploidy status, we found that the preparation of metaphase spreads, which showed the clear chromosomal images containing the normal number of chromosomes, was possible from the veliger stage larvae. On the other hands, all larvae used in this study regardless of developmental stage and ploidy did not show colchicine sensitivity. Moreover, no significant difference was observed in cell cycle distribution of the cells comprising larvae between two developmental stages regardless of ploidy status. These suggested that the details of protocol to prepare metaphase spreads from abalone larvae should be optimized depending on its developmental stages. Taken together, we demonstrated the feasibility of preparing metaphase spreads from H. discus hannai veliger stage larvae for karyotype analysis.

Among various methods to produce graphene sheets, electrochemical exfoliation has been regarded as an effective method for the mass production of high-quality graphene sheets because of its simplicity and environmental friendliness. However, conventional electrochemical exfoliation has a disadvantage of accumulating intercalating ions at graphite interlayers owing to the use of a constant voltage. In this study, we developed a DC switching technique to achieve more efficient intercalation of ions than that in the conventional method. In the DC switching method, positive and negative voltages are successively applied to release the accumulated intercalating ions. By testing various conditions, we found the optimum switching time to produce high-quality graphene sheets with the highest yield rate and the highest electrical conductivity. As a result, the graphene sheets using this DC switching technique showed 85% higher yield rate, 193% higher electrical conductivity, 160% larger area, and 25% thinner thickness than those obtained when using a constant DC method. We believe that this DC switching technique can be used for large-scale production of high-quality graphene sheets.

In this paper, AgCl/Ag3PO4/diatomite photocatalyst is successfully synthesized by microemulsion method and anion in situ substitution method. X-ray diffraction (XRD), photoelectron spectroscopy (XPS), scanning electron microscopy (SEM), energy dispersive spectroscopy (EDS), transmission electron microscopy (TEM), and ultraviolet-visible spectroscopy (UV-Vis) are used to study the structural and physicochemical characteristics of the AgCl/Ag3PO4/diatomite composite. Using rhodamine B (RhB) as a simulated pollutant, the photocatalytic activity and stability of the AgCl/Ag3PO4/diatomite composite under visible light are evaluated. In the AgCl/Ag3PO4/diatomite visible light system, RhB is nearly 100 % degraded within 15 minutes. And, after five cycles of operation, the photocatalytic activity of AgCl/Ag3PO4/diatomite remains at 95 % of the original level, much higher than that of pure Ag3PO4 (40 %). In addition, the mechanism of enhanced catalytic performance is discussed. The high photocatalytic performance of AgCl/Ag3PO4/diatomite composites can be attributed to the synergistic effect of Ag3PO4, diatomite and AgCl nanoparticles. Free radical trapping experiments are used to show that holes and oxygen are the main active species. This material can quickly react with dye molecules adsorbed on the surface of diatomite to degrade RhB dye to CO2 and H2O. Even more remarkably, AgCl/Ag3PO4/diatomite can maintain above 95 % photo-degradation activity after five cycles.

Fly ash consists of various metal oxides which can remove SO2 gas by the catalyst effect. When fly ash is added in the preparation process of pitch-based activated carbon, the pitch particles aggregate and fly ash is embedded in the activated carbon. To increase SO2 gas removal performance, activated carbon was prepared by surface-treated fly ash and petroleum-based pitch. Carboxyl groups were introduced into the fly ash by malic acid treatment. The introduced carboxyl groups acted as an activation agent to create micropore around the fly ash, and created micropores were exposed to the fly ash outside of the activated carbon. The exposed fly ash increased removal amount of SO2 gas by a catalytic effect of the metal oxides. The SO2 gas removal performance improved by 34% because of the catalyst effect of the exposed fly ash and improvement in the micropore structure in the activated carbon.

In the present study, carbon molded bodies were prepared by using graphite/coke fillers and petroleum-based binder pitch with various softening points, and the thermal properties of the prepared carbon molded bodies were investigated. The ratio of a binder affects the molded body preparation: no molded body was prepared at a low binder pitch content, and swelling occurred during the thermal treatment at a high binder pitch content. The binder pitch thermal treatment yield was the highest at 41 wt% at the softening point of 150 °C and the lowest at 23 wt% at the softening point of 78 °C. A significant mass reduction was found in the range of 150 to 300 °C in the petroleum-based binder pitch, and in the range of 300 to 475 °C in the coal-based binder pitch. The molecular weight of the binder pitch was analyzed through the matrix-assisted laser desorption/ionization time-of-flight (MALDI-TOF) method. The molecular weight ratio within the interval showing the highest binder pitch molecular weight (178 to 712 m/z) was the highest at 66.4% in the coal-based binder pitch (softening point 115 °C) and the lowest at 46.0% in the petroleum-based binder pitch (softening point 116 °C). When the petroleumbased binder pitch was applied, as the softening point was increased, the voids decreased and thus the thermal conductivity increased. The highest thermal conductivity was 99.5 W/mK for the carbon molded bodies prepared using the coal-based binder pitch and 102.8 W/mK for those prepared by using the petroleum-based binder pitch. The results showed that the thermal properties were similar between the coal-based binder pitch (softening point 115 °C) and the petroleum-based binder pitch (softening point 150 °C).