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박승제,김명호 한국농업기계학회 1998 바이오시스템공학 Vol.23 No.6
This study was performed to determine the kinetic friction coefficient bulk density, dynamic and static angle of repose, and terminal velocity of the chopped rice straw in the moisture range of 8~23%, which could be used for better design and operation of the processing machinery and handling facilities. Friction coefficient was determined from the horizontal traction force measured by pulling the container holding the mass of rice straw on the various plate materials. Bulk density was measured with an apparatus consisting of a filling funnel and a receiving vessel. Dynamic angle of repose was calculated from the photos of bulk samples piled by gravity flow on a circular platform. Static angle of repose was determined by measuring the side angle of the bulk material which was left in the cylindrical container after natural discharge of the bulk sample through a circular hole in the bottom plate. Kinetic friction coefficients of rice straw on the PVC, mild steel, stainless steel, and galvanized steel were in the range of 0.303~0.434, 0.222~0.439, 0.204~0.448, and 0.206~0.407, respectively. and indicated linear increase with moisture content. The effects of moisture change on the friction coefficients were in the order of PVC, mild steel, galvanized steel, and stainless steel. Bulk density, dynamic and static angle of repose, and terminal velocity were in the range of 56.8~60.3 kg/m$^3$, 41.4~45.9$^{\circ}$, 94.4~100.8$^{\circ}$, and 1.07~4.48 m/s, respectively, and were increased linearly with the moisture content.
하지동맥경화증에 있어 3차원적 나선형 전산화 단층촬영 혈관조영술의 유용성
박승제 대한영상의학회 1997 대한영상의학회지 Vol.36 No.2
Purpose : To assess the usefulness of three-dimensional spiral CT angiography in the diagnosis and as a guide for the treatment of arteriosclerosis obliterans of the lower extremity. Materials and Methods : During a recent one-year period, CTA and conventional angiography were performed in 12 patients with suspected ASO. From the upper margin of the third lumbar vertebral body to below the knee joint, helical CT scanning was performed 30-45 seconds after the injection of Ultravist 370(150-180ml) by a power injector at the rate of 2.5-3.0ml/sec via the antecubital vein. The resulting data were reformatted by SSD after reconstruction of 5mm intervals, and CTA was compared with CA for site and degree of stenotic or occlusive lesion. Results : On CTA and CA, twenty-three occlusive lesions above the tibioperoneal artery were detected in 12 patients. On CA, three mild seven moderate and eight severe stenoses were seen, as well as five occlusions. There were three cases of overgrading and three of undergrading. Overall diagnostic accuracy was 73.9%(17/23). Calcifications were detected on axial CT scanning in two of three underestimated lesions. Migration of the thrombi was noted in one case. Conclusion : CTA may be useful in the evaluation of the arteries of the lower extremities, and valuable in the planning and follow-up of treatment.
박승제,김명호,신현명 한국농업기계학회 2005 바이오시스템공학 Vol.30 No.4
For better and large utilization of rice husk, the production and consumption status, differences in chemical composition and heating value due to region and variety, and thermogravimetric characteristic of rice husk were studied. In addition, the differences in chemical composition due to region and variety and the crystallization characteristic of rice husk ash were also studied. Approximately 800,000 M/T of rice husk was produced per year in Korea, which is about 18% of the paddy production by weight. Noticeable varietal and regional difference pattern in chemical composition was not found among the domestic rice husk samples. Their average ash content and higher heating value were 16.4% and 16,660 kJ/kg by dry basis, respectively. A relation seemed to exist between the carbon content and higher heating value. Noticeable difference pattern in chemical composition was not found among the domestic rice husk ash samples. The SiO2 contents were a little low, the maximum being 92.9%, and the contents of major components such as CaO, MgO, and K2O were also lower compared with foreign rice husk ash due to the deficiency of compost matters in domestic soils. Thermogravimetry study showed the thermal decomposition of rice husk started at about 250℃, followed by relatively fast combustion of combustible gas until the temperature rose to 350℃. After 350℃, combustion of the carbon component proceeded relatively slowly as the temperature increased. Therefore, the ignition temperature of the rice husk could be estimated around 300℃. Crystallization of SiO2 in the rice husk ash was found from the combustion temperature of 750℃ and became distinctly when the combustion temperature exceeded 900℃. The ash became darker with SiO2 crystallization.
박승제,김성민,김명호,김철수,이종호 한국농업기계학회 2000 바이오시스템공학 Vol.25 No.2
This study was performed to develop a prototype continuous flow ginseng dryer with which better product quality and lower drying energy consumption could be achieved compared with conventional ginseng dryers. A dryer having both far infrared ray (IR) and heated-air as the drying energy sources was designed and fabricated . Dryer performance was studied by examining energy efficiencies and dryer performance evaluation indices (DPEI) during the drying tests of medium-sized four year ginseng roots with IR radiating plate temperature and drying air temperature in the range of 80-12$0^{\circ}C$ and 22-5$0^{\circ}C$, respectively. The DPEI of IR /heated -air combined drying was 1/3 of that of the conventional heated-air drying when ginseng were dried to the same final moisture ratio. When ginsengs were dried for 12 hours in the prototype IR/heated-air combination dryer, a linear relationship was found to exist between final moisture ratio and ginseng temperature. As the drying progressed, drying air temperature inside the dryer was nearly constant but ginseng temperature was drastically increased during the first two hours and gradually increased thereafter until the end of drying. With the prototype Ir/heated-air combination dryer, the drying rate changed little but the energy efficiency increased proportionally when the amount of ginseng to be dried increased. Drying capacity, energy efficiency, and DPEI of the prototype IR/heated-air combination ginseng dryer were estimated to 1.500 roots, 65% and 3.800kJ/kg-water , respectively.