• Journal of the Korean Ceramic Society
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• v.16 no.2
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• pp.99-105
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• 1979

Themogravimetric analysis was used to investigate the kinetics of the $Si_3N_4$ formation from Korean rice hulls in the temperature range from $1990^{\circ}C$ to $1370^{\circ}C$. The experimental results indicated that the reaction rate controlling step in the overall process is the diffusion of CO gas from the surface of carbon particle to main body of $N_2$ gas fluid through the stagnant gas film around the carbon particle. The kinetics followed a nearly linear rate law at the initil reaction stage. The activiation energy for the formation of $Si_3N_4$ from Korean rice hulls was 43.5Kcal/mole.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2009.04a
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• pp.511-517
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• 2009

The mechanical impedance and stiffness of the foundation of shipboard equipments and hulls supported by anti-vibration mount are very important so that the anti-vibration mount can accomplish its performance effectively. But, it is frequently argued how much stiffness and mechanical impedance are necessary for those foundations and hulls. In this research, it is discussed by evaluating the dynamic stiffness of the commercial anti-vibration mounts used in a naval vessel. Consequently, in this research, the minimum level of the mechanical impedance and stiffness of the foundation of shipboard equipments and hulls are suggested considering the dynamic stiffness of the mount which varies as frequency.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.19 no.3
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• pp.320-326
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• 2009

The mechanical impedance and stiffness of the foundation of shipboard equipments and hulls supported by anti-vibration mount are very important so that the anti-vibration mount can accomplish its performance effectively. But, it is frequently argued how much stiffness and mechanical impedance are necessary for those foundations and hulls. In this research, it is discussed by evaluating the dynamic stiffness of the commercial anti-vibration mounts used in a naval vessel. Consequently, in this research, the minimum level of the mechanical impedance and stiffness of the foundation of shipboard equipments and hulls are suggested considering the dynamic stiffness of the mount which varies as frequency.

• Korean Journal of Soil Science and Fertilizer
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• v.29 no.2
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• pp.124-129
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• 1996

This experiment has been conducted to find out a effective decomposition method of popped rice hulls which are hard to be decomposed in vitro. It was found that the C/N ratio of 35 was better than the C/N ratio of 20 for improving the decomposition ratio of popped rice hulls. The addition of rice bran accelerated the decomposition of popped rice hulls. The real decomposition rate of popped rice hulls for 10 days was merely 8 percent. This poor decomposition ratio seemed to be come from the chemical constituent of rice hull which has 20 percent of silica content. It was considered that the addition of rice bran speeded up only the decomposition of bran itself by increasing the number of microorganisms. It was also observed that color changes developed from the decomposition of rice hulls proved not to be a yardstick for the degree of decomposition.

• Journal of Nuclear Fuel Cycle and Waste Technology(JNFCWT)
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• v.13 no.3
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• pp.211-218
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• 2015

The reaction rates of ZIRLO cladding hulls with cross-section openings were investigated using a thermo-gravimetric analysis system in order to identify whether selective recovery of Zr from oxidized cladding hulls is possible. The experimental results showed that an oxidized ZIRLO cladding hull was not reactive with chlorine gas at 400℃. However, providing fresh cross-sections on one or both ends of the ZIRLO hulls enabled a chlorination reaction. This reaction was completed after 8 hours; a 14% increase on the 7 hours seen with a bare ZIRLO cladding hull. The Sharp-Hancock plot analysis results revealed that the contracting volume model is the best for describing the reaction between the cross-section opened ZIRLO hulls and chlorine gas under the condition of this work. It was concluded that the chlorination process can be employed for oxidized ZIRLO cladding hulls by providing cross-section openings.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2008.06a
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• pp.501-502
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• 2008

• 한국생태학회:학술대회논문집
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• 2002.08a
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• pp.79-82
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• 2002

Main attackers on pine seeds on the forest floor were investigated in Korea. Damage on pine cones begins in early stage of cone formation, especially by squirrel and Korean squirrel. The above animals left Kayak-like hulls of seed on rocks and fallen tree trunk. Field mice also left the same shape of Kayak-like hulls. But birds including doves and peasants left large shreds with longitudinal cracks or seed cup trace. Most of seeds on the leaf litters as well as under the fallen leaf were consumed by fold mice and birds. Especially fold mice found the seeds under fallen leaves and consumed all of them.

• The Korean Journal of Ecology
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• v.25 no.4
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• pp.213-216
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• 2002

Main attackers on pine seeds on the forest floor were investigated in Korea. Damage on pine cones begins in early stage of cone formation, especially by squirrel and Korean squirrel. The above animals left Kayak-like hulls of seed on rocks and fallen tree trunk. Field mice also left the same shape of Kayak-like hulls. But birds including doves and peasants left large shreds with longitudinal cracks or seed cup trace. Most of seeds on the leaf litters as well as under the fallen leaf were consumed by field mice and birds. Especially field mice found the seeds under fallen leaves and consumed all of them.

• Bulletin of the Society of Naval Architects of Korea
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• v.7 no.2
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• pp.19-26
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• 1970

Three kinds of high speed boat have been tested in the Seoul National University tank. Under the range of speed length ratio 2.5, displacement hulls have shown less resistance value than planing hull, but over the range of 3.0, planing hulls are better. Change of resistance due to the change of displacement is more severe in planing hull.

• International Journal of Naval Architecture and Ocean Engineering
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• v.7 no.3
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• pp.500-508
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• 2015

High-speed heavy loaded monohull ships can benefit from application of drag-reducing air cavities under stepped hull bottoms. The subject of this paper is the steady hydrodynamic modeling of semi-planing air-cavity hulls. The current method is based on a linearized potential-flow theory for surface flows. The mathematical model description and parametric calculation results for a selected configuration with pressurized and open air cavities are presented.