• 자연과학논문집
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• 제5권1호
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• pp.77-86
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• 1992

양이온 교환반응에 의해 몬트모릴로나이트내의 금속 양이온을 긴 chain을 갖는 유기 양이온 tenside로 치환시킴으로써 물성이 다른 몬트모닐롤나이트의 층간화합물을 형성하게 된다. 이러한 층간화합물은 공업적으로 아주 광범위하게 이용되는가 하면, model-systems로서 물질의 거동을 밝혀내는 학문적 연구에 또한 많이 이용되기도 한다. 따라서 본 연구에서는 이러한 몬트모릴로나이트의 층간화합물을 형성하여 여러 상이한 조건하에서의 이들의 거동에 대하여 연구했다.

• Journal of Semiconductor Engineering
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• 제1권1호
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• pp.46-56
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• 2020

This article highlights new opportunities of inorganic semiconductor materials for bio-implantable electronics, as a subset of 'transient' technology defined by an ability to physically dissolve, chemically degrade, or disintegrate in a controlled manner. Concepts of foundational materials for this area of technology with historical background start with the dissolution chemistry and reaction kinetics associated with hydrolysis of nanoscale silicon surface as a function of temperature and pH level. The following section covers biocompatibility of silicon, including related other semiconductor materials. Recent transient demonstrations of components and device levels for bioresorbable implantation enable the future direction of the transient electronics, as temporary implanters and other medical devices that provide important diagnosis and precisely personalized therapies. A final section outlines recent bioresorbable applications for sensing various biophysical parameters, monitoring electrophysiological activities, and delivering therapeutic signals in a programmed manner.

• 한국재료학회지
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• 제7권6호
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• pp.529-535
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• 1997

Li ion전지용 LiMn$_{2}$O$_{4}$분말을 졸-겔법과 고상반응법으로 제조하여 분말의 특성과 전지의 특성을 비교하였다. 졸-겔법에 의해 제조된 LiMn$_{2}$O$_{4}$분말은 고상반응법에 의해 제조된 분말보다 낮은 온도에서 합성이 가능하고, 균질하고 작은 입자들로 구성되었으며, Li stoichiometry가 우수하여 전지의 방전용량이 크나 양이온 혼합도가 높아 전지의 내부저항이 크게 나타났다. 졸-겔법은 높은 Li stoichiometry와 균질한 입자 크기를 갖는 LiMn$_{2}$O$_{4}$분말 제조에 적당한 것으로 생각되며, 전지의 내부저항 문제는 분말의 하소온도와 냉각속도의 조절에 의해 가능할 것으로 판단된다.

• 한국환경보건학회지
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• 제20권2호
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• pp.73-79
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• 1994

The effects of packing materials in the anaerobic reactor and inorganic chemicals in the synthetic wastewater on the anaerobic treatment during the start up period were investigated using anaeroic filter process. The Ringlace and Honeycomb tube as packing materials were used in the anaerobic reactors. The Ca$^{2+}$ and Fe$^{2+}$ ion concentration as inorganic chemicals contained higher 40 times and 100 times as compared to the control synthetic wastewater, respectively. A start up period 104 and 150 days were necessary to achieve loading rate of 0.37 and 0.74 kg-Toc/m$^3$.d in the anaerobic filter process packed by Ringlace and Honeycomb tube, respectively. The loading rates of the reactor using the synthetic wastewater containing Ca$^{2+}$ (40 times) could be increased faster than in the reactors using the synthetic wastewater containing Fe$^{2+}$ ion (100 times) and control synthetic wastewater. The results of XMA analysis that a lot of the Ca$^{2+}$ ion on the surface of the anaerobic sludge in the anaerobic reactor packed by Ringlace which were fed supplied with synthetic wastewater containing Ca$^{2+}$ ion (40 times) observed as compared to the reactors supplied with control synthetic wastewater and containing Fe$^{2+}$ ion (100 times).

• 한국결정성장학회지
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• 제5권3호
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• pp.209-214
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• 1995

99.9%의 $Fe_2O_3$ 를 0.2 wt% 첨가한 $SrTiO_3$ 단결정을 air 분위기와 질소분위기하에서 floating zone 법으로 성장시켰다. 성장속도는 5mm/hr 였으며 회전속도는 30rpm이었다. 육성한 결정을 성장방향에 수직하게 절단하여 준비한 시편을 질소분위기하에서 900, 1000, $1100^{\circ}C$에서 2시간동안 annealing한 후 비저항을 측정하였다. 측정한 비저항치를 전기전도도로 전환하고 이를 이용해 계산한 activation energy로서 전기전도도 향상기구를 설명하고자 하였다.

• 마이크로전자및패키징학회지
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• 제20권2호
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• pp.1-9
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• 2013

Recently flexible electronic devices have attracted a great deal of attention because of new application possibilities including flexible display, flexible memory, flexible solar cell and flexible sensor. In particular, development of flexible memory is essential to complete the flexible integrated systems such as flexible smart phone and wearable computer. Research of flexible memory has primarily focused on organic-based materials. However, organic flexible memory has still several disadvantages, including lower electrical performance and long-term reliability. Therefore, emerging research in flexible electronics seeks to develop flexible and stretchable technologies that offer the high performance of conventional wafer-based devices as well as superior flexibility. Development of flexible memory with inorganic silicon materials is based on the design principle that any material, in sufficiently thin form, is flexible and bendable since the bending strain is directly proportional to thickness. This article reviews progress in recent technologies for flexible memory and flexible electronics with inorganic silicon materials, including transfer printing technology, wavy or serpentine interconnection structure for reducing strain, and wafer thinning technology.

• 한국세라믹학회지
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• 제31권10호
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• pp.1159-1168
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• 1994

We powders were synthesized from W powders in differnet particle sizes by Self-propagating High-temperature Synthesis process (SHS) using a chemical furnace. The effects of the mole ratio of chemical fuel content, pellet thickness and the mole ratio between carbon and tungsten (C/W Ratio) on synthesis were investigated with the tungsten powders have different particle size each other. Compositional and structural characterization of these powders was carried out by scanning electron microscope (SEM0 and x-ray diffractometer. Powder characterization was carried out by the measurement of particle size distribution with laser-particle size analyzer. The amounts of WC obtained by SHS process depend very much on the particle size of tungsten powder and heat contents given in a product, i.e. as the particle size of W powder is smaller, the amounts of WC produced increase. Also the more heat contents is given, the more amounts of WC increase. By optimizing the synthesis conditions, it is possible to fabricate WC powders which have little secondary phases (W2C, C).

• 한국결정성장학회지
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• 제5권2호
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• pp.87-93
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• 1995

Floating zone법으로 strontium titanate 단결정을 육성하였다. 성장조건은 공기 분위기하에서 성장속도 3mm/hr, 상부축 회전속도 20~25rpm, 하부축 회전속도 15~20rpm이었으며 육성한 단결정은 옅은 갈색을 띄고 있었으며 투명하였고 annealing 후 색깔이 옅어짐을 확인할 수 있었다. 성장방위는 [112] 방향이었으며 XRD, EDS로 화학양론적인 조성은 $SrTiO_3$단일 결정상임을 알 수 있었다. $350^{\circ}C$, KOH용액에서 5분동안 chemical etching하여 etch pit pattern을 조사하였으며 상온하에서$350^{\circ}C$의 온도 범위에서 유전상수 값을 조사하였다.

• The Korean Journal of Ceramics
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• 제4권3호
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• pp.183-188
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• 1998

Gas sensitizations of tin oxide film were investigated by measuring the change of film resistance in various gas atmospheres such as $N_2,\; O_2,\; H_2O$. The main test sample, polycrystalline $SnO_2$ film containing small Sb as a dopant was prepared by a sputtering technique and showed a long term stability in base resistance and thus, in gas sensitivity. The adsorption of oxygen on the film surface as a type of $(O_{ads})$ at the temperature of around $300^{\circ}C$ played important roles in sensor operating mechanism. The roles were ⅰ) the increase of base resistance in ambient air, which consequently lead to high sensitivity and ⅱ) the promotion of fast recovery. The reaction of hydrogen gas with the already adsorbed $(O_{ads})$ ions was considered as a decisive sensitization mechanism of tin oxide film. However, the dissociation of hydrogen molecules on film surface, by direct donation of electron to film also took a major part in the sensitization. The effect of humidity on gas sensitization was found to be negligible at the sensor operating temperature of around $300^{\circ}C$.

• Macromolecular Research
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• 제16권7호
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• pp.626-630
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• 2008

Poly(vinyl pyrrolidone) was used successfully to control the size and distribution of silver nanoparticles generated on inorganic silica nanofibers. The inorganic nanofibers were electro spun using sol-gel chemistry of silicates, and the diameter of the prepared nanofibers was unaffected by adding up to 7% of poly(vinyl pyrrolidone). The silver ions, in the form of silver nitrate, were introduced into the silica nanofibers and reduced to metallic silver by ultraviolet irradiation with a subsequent thermal treatment. The size of the generated silver particles was decreased dramatically by adding poly(vinyl pyrrolidone). The size of the silver nanoparticles was 73 nm when no poly(vinyl pyrrolidone) was added but 23 nm with the addition of only 1% of poly(vinyl pyrrolidone). The extent of reduction could be checked by determining the concentration of silver ions leached into water from the silica nanofibers. After thermal treatment of the silica nanofibers, more than 99% of the silver remained in the nanofibers, indicating almost complete reduction of the silver ions to silver metal.