보일러 관의 부식 현상은 오랫동안 다양한 산업분야 걸쳐 제기되어 오는 주요한 문제 중의 하나이다. 특히, 온도는 보일러 관의 부식 현상을 야기시키는 주요한 영향 인자 중에 하나이다. 하지만, 기존의 보일러 시스템의 경우 장기간의 운전으로 인해 온도에 따른 부식 발현을 면밀히 관찰하기에는 부적합한 부분이 있다. 따라서 우리는 기존의 보일러 설비처럼 보일러 관의 내부와 외부 온도조건을 달리하여 제어할 수 있는 장비를 구축하였다. 이를 통해서 다양한 온도 및 환경조건에서 보일러 관의 고온 부식에 대한 실험을 진행할 수 있었다. 결국 FE-SEM(field emission scanning electron microscope), EDS(energy dispersive spectrometer), XRD(X-ray diffraction)를 통한 분석결과로부터 다각적으로 고온 조건에 인한 부식발생기작에 대해 유추할 수 있었다. 뿐만 아니라 weight loss method를 통해서 고온에 따른 부식으로 인한 보일러 관의 두께 및 무게 감량 결과를 통해서 해당 조건에서의 보일러 관의 수명 또한 예측할 수 있었다.

This study describes development of high performance environmental barrier coating for steel in oxidizing and humidity environments at elevated temperature. Parameters like pre-treatment of the steel substrates, filler systems, particle size of the fillers or coating thickness were varied to optimize the coatings. The resulting coating investigated by TGA, SEM/EDS, and XRD to clarify the possible protective mechanism. Oxidation tests, adhesion tests, thermal shock resistance tests and humidity resistance tests were performed to evaluation the high performance of developed coatings.

High temperature corrosion is a major issue in waste-to-energy (WTE) facilities because it effects running cost and energy utilization efficiency. Corrosion of heating surfaces in WTE boilers is a complex phenomenon. The purpose of this study was to analyze the high temperature corrosion characteristics of WTE boiler tubes and to determine the influences of high temperature corrosion on heat exchange. Heating surface corrosion samples for this research were obtained from a superheater tube in municipal solid refuse fuel-fired power plant. Surface morphology, microstructure and phase composition were characterized by scanning electron microscopy, energy-dispersive X-ray spectroscopy, and X-ray diffraction analysis. The morphology of the heating surface was rough and had porous structures. The chlorine content of the surface was 7.4wt.% and the samples were mainly composed of hematite (Fe2O3) and magnetite (Fe3O4). The thermal conductivity of the corrosion samples was characterized using thermal conductivity measurements and was found to be 2.33 W/mK at 500oC. This result, which is 17 times less than that of boiler tube carbon steel (40.40 W/mK), indicates that corrosion of WTE boiler tubes is closely related to a decrease in boiler heat exchange efficiency.

Human embryonic stem (ES) cells are a potential source of cells for developmental studies and for a variety of applications in transplantation therapies and drug discovery. However, human ES cells are difficult to culture and maintain at a large scale, which is one of the most serious obstacles in human ES cell research. Culture of human ES cells on MEF cells after disassociation with accutase has previously been demonstrated by other research groups. Here, we confirmed that human ES cells (H9) can maintain stem cell properties when the cells are passaged as single cells under a feeder-free culture condition. Accutase-dissociated human ES cells showed normal karyotype, stem cell marker expression, and morphology. We prepared frozen stocks during the culture period, thawed two of the human ES cell stocks, and analyzed the cells after culture with the same method. Although the cells revealed normal expression of stem cell marker genes, they had abnormal karyotypes. Therefore, we suggest that accutase-dissociated single cells can be usefully expanded in a feeder-free condition but chromosomal modification should be considered in the culture after freeze-thawing.