In the present work, we synthesize nano-sized ZnO, SnO2, and TiO2 powders by hydrothermal reaction using metal chlorides. We also examine the energy-storage characteristics of the resulting materials to evaluate the potential application of these powders to dye-sensitized solar cells. The control of processing parameters such as pressure, temperature, and the concentration of aqueous solution results in the formation of a variety of powder morphologies with different sizes. Nano-rod, nano-flower, and spherical powders are easily formed with the present method. Heat treatment after the hydrothermal reaction usually increases the size of the powder. At temperatures above 1000oC, a complete collapse of the shape occurs. With regard to the capacity of DSSC materials, the hydrothermally synthesized TiO2 results in the highest current density of 9.1 mA/cm² among the examined oxides. This is attributed to the fine particle size and morphology with large specific surface area.

In the present work, we use multiwall carbon nanotubes (MWCNT) as the starting material for the fabrication of sintered carbon steel. A comparison is made with conventionally sintered carbon steel, where graphite is used as the starting material. Milling is performed using a horizontal mill sintered in a vacuum furnace. We analyze the grain size, number of pores, X-ray diffraction patterns, and microstructure. Changes in the physical properties are determined by using the Archimedes method and Vickers hardness measurements. The result shows that the use of MWCNTs instead of graphite significantly reduces the size and volume of the pores as well as the grain size after sintering. The addition of Y2O3.to the Fe-MWCNT samples further inhibits the growth of grains.

Copper nanoparticles attract much attention as substitutes of noble metals such as silver and can help reduce the manufacturing cost of electronic products due to their lower cost and good conductivity. In the present work, the chemical reduction is examined to optimize the synthesis of nano-sized copper particles from copper sulfate. Sodium borohydride and ascorbic acid are used as reducing and antioxidant agents, respectively. Polyethylene glycol (PEG) is used as a size-control and capping agent. An appropriate dose of PEG inhibits the abnormal growth of copper nanoparticles, maintaining chemical stability. The addition of ascorbic acid prevents the oxidation of nanoparticles during synthesis and storage. Transmission electron microscopy (TEM) and Fourier transform infrared spectroscopy (FTIR) are used to investigate the size of the synthesized nanoparticles and the coordination between copper nanoparticles and PEG. For chemical reduction, copper nanoparticles less than 100 nm in size without oxidized layers are successfully obtained by the present method.

2년마다 실시되는 UN의 전자정부시스템 평가에서 한국의 전자정부 시스템은 2010, 2012, 2014년 3차례 걸쳐 1위로 평가되었다. 1978년 시작되어 이제는 해외로 수출까지 되는 한국 전자정부 시스템의 진화에 있어서 표준의 역할에 대해서는 그다지 알려진 바가 없 다. 한국의 전자정부 시스템 발전에 어떠한 표준들이 어떠한 역할을 수행했으며, 이러한 표 준이 제대로 기능하기 위하여 어떠한 제반 환경이 필요하고, 어떠한 노력이 경주되었는지 사 례 연구를 수행하여 밝히고자 한다. 행위자 연결망 이론(Actor Network Theory)과 구조화 이론(Structuration theory)을 이론적 기반으로 하여, 표준이 행위자 연결망 이론 관점에서 어떠한 역할을 수행해 왔는지를 전자정부 시스템 발전에 직접 관여되었던 행정자치부 전자 정부담당 현/전직 관리자급 공무원, 표준담당관, NIA 표준 담당관, 민간 SI 업체 등 관련 전 문가(관리자급)분들과의 인터뷰와 문헌 연구를 바탕으로 사례 분석을 실시하고자 한다.

In the present work, we investigated the mechanical alloying of binary Ga-Se(1:1) and Ga-Te(1;1) sysyems. The high-energy ball-milling was performed at 40℃ where one of constituents (Ga) is molten state. The purpose of the work was to see whether reactions between constituent elements are accelerated by the presence of a liquid phase. During the ball-milling, the liquid Ga phase completely disappeared and the resulting powders consist of nanocrystalline grain of ~20 nm with partly amorphized phases. However, no intermetallic compounds formed in spite of the presence of the liquid phases which has much higher diffusivity than solid constituents. By subsequent heat-treatments, the intermetallic compounds such as GaSe and GaTe formed at relatively low temperatures. The formation temperature of theses compound was much lower than those predicted by equilibrium phase diagram. The comparison of the ball-milled powders with un-milled ones indicated that the easy formation of intermetallic compound or allying occurs at low temperatures.

We examined various ball-milling parameters which affect the structural and morphological modification of multi-wall carbon nanotubes. In particular, the effect of milling mode and the use of different milling agents were exam- ined. Friction milling mode induced more structural changes than impact milling mode except the use of dry ice as a milling agent. Wet milling was helpful for reducing more effectively the agglomeration of nanotubes than dry milling. The use of hard solid particles such as silica and alumina as milling agents resulted in an effective shortening of nan- otubes, but often susceptible to the amorphization and the destruction of crystallinity.

Al/AlN composites were synthesized by mechanical alloying using process control agents(PCAs). Three different PCAs which contain N element, were examined to see the effectiveness of ball-milling and the nitridation during sintering. Among examined PCAs, was the most effective to facilitate ball-milling and to form nitrides during a subsequent sintering. By a proper control of ball-milling and sintering, we could obtained surface-hardened Al-based composites.

nanowires were synthesized by a hydrothermal reaction of metallic Y with aqueous solution of LiOH. The morphology and the size of the nanowires changed with varying the volume of the LiOH solution inside the autoclave. nanowires transformed to by a subsequent heat-treatment without morphological change. By a proper control of hydrothermal reaction parameter and heat-treatment, the yield of pure nanowires up to 97% was attained.

Carbon nanotube (CNT)/ composites were synthesized to enhance the hydrogen storage properties. The emphasis was made on the effect of different shortening methods of CNTs on the open-tip structure and the resulting properties. The use of open CNTs as a starting material resulted in an enhanced hydrogen properties of CNT/ composites. Among the employed methods for the shortening of CNTs, wet milling using ethanol was the most efficient, while ultrasonic acid treatment or thermal decomposition resulted in a less hydrogen storage capacity.

Amorphous carbon nanotubes were synthesized by a reaction of benzene, ferrocene and Na mixture in a small autoclave at temperatures as low as . The resulting carbon nanotubes were short and straight, but their inner hole was filled with residual products. The addition of quartz to the reacting mixture considerably promoted the formation of carbon nanotubes. A careful examination of powder structure suggested that the nanotubes in this process were mainly formed by surface diffusion of carbon atoms at the surface of solid catalytic particles, not by VLS(vapor-liquid-solid) mechanism.

탄소재료는 결정구조에 따라 카본블랙(carbon black), 그라파이트(graphite), 탄소섬유(carbon fiber) 등 다양한 형태가 있으며 그 응용 또한 광범위하다. 이는 탄소재료가 화학적으로 매우 안정하고, 열 및 전기전도성이 우수하며, 기계적인 특성면에서도 고강도, 고탄성율을 가지고 있어서 구조적으로 안정하기 때문이다. 특히 (fullerene)와 탄소나노튜브(carbon naotube : CNT)등 근래 새로이 발견된 탄소물질들 은 그

The Sn - graphite composites were prepared by chemical encapsulation method for anode materials in Li-ion batteries. EDS and XRD analysis confirmed the presence of Sn in the graphite structure. Cyclic voltammometry (CV) measurement shows extra reduction and oxidation peaks, which might to be related to the formations of alloy compounds. Graphite-tin composite electrodes demonstrated higher Lithium storage capacities than graphite electrodes. Due to the nature of fine Sn particles on graphite surface, the graphite-tin composite electrodes have shown a good cycle properties.