• KSBB Journal
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• v.9 no.4
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• pp.412-417
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• 1994

The biodegradable characteristics of starch-filled polyethylene film by fungi were investigated. Aspergillus niger showed the highest cell growth among five species of fungi used in the experiment. Higher starch content gave the higher growth rate of A. niger; however, the kind of film or cutting direction did not give any effects on the cell growth. The use of vinyl trimethoxysilane for the stronger binding of starch and polyethylene did not inhibit the cell growth. When the starch content was higher than 10%, the elongation of the film decreased significantly after the growth of microorganism in the case of transverse direction samples.

• The Journal of the Korean dental association
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• v.12 no.3
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• pp.173-175
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• 1974

The author had studied epidemiologically the dental caries experience rate in the 200 students of nursing school of national medical center. The obtained results were as follows; 1. The dental caries experience rate in the students of nursing school of N.M.C. was 78.5%. 2. The D.M.F. teeth index in the students of nursing school of N.M.C was 4.5. 3. The filled teeth rate of students of nursing school of N.M.C. was lower than decayed teeth rate and missed teeth rate.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 1999.05a
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• pp.548-551
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• 1999

The cure characteristics of metal particle filled DGEBA/MDA/SN/ zeolite epoxy resin composite system for EMI shielding were investigated by dynamic DSC run method and FT-lR spectroscopy. As the heating rate increased, the peak temperature on dynamic DSC curve increased because of the rapid cure reaction. From the straight line of the Kissinger plot, the curing reaction activation energy and pre-exponential factor could be obtained. As the post-curing time at 15$0^{\circ}C$ increased, the glass increased the glass transition temperature or the thermal stability increased. When the post curing time is too long, the system filled with metallic Al particle can be thermally oxidized by the catalytic reaction of metal filler and the thermal stability of the composite for the EMI shielding application may be decreased.

• Macromolecular Research
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• v.8 no.2
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• pp.73-79
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• 2000

The influence of mastication of natural rubber (NR) on properties of carbon black-filled NR compounds was studied. Variations of viscosities of the masticated NR and the carbon black-filled NR compound by heating were also investigated. The viscosities of the compounds decreased by increasing the mastication time of the raw rubber. The viscosities of the masticated NR and the compounds increased by increasing the heating time. This was explained by the combination reaction between functional groups in the rubber. The viscosity increment of the masticated rubber and the compounds by heating became larger with increased mastication time. Cure rate of the compound became faster by increasing the mastication time. Modulus of the vulcanizate made of the rubber masticated for a long time was higher than that of the vulcanizate made of the rubber masticated for a short time while elongation at break of the former was shorter than that of the latter. This was explained by the content of bound rubber and chain length of the rubber molecules.

• Proceedings of the Korean Society of Medical Physics Conference
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• 2002.09a
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• pp.328-330
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• 2002

Large balloon angio catheter is used for Percutaneous Transluminal Angioplsty(TPA) of the iliac, femoral and renal arteries as well as after Transjugular Intrahepatic portosystemic shunt(TIPS). The use of angioplasty balloon filled with liquid form of radioisotope reduces the rate of restenosis after PTA. The purpose of this study was to evaluate the absorbed dose to the target vessels from various sized large balloon filled with liquid form of Ho-166-DTPA. Four balloons of balloon dilatation catheters evaluated were 5, 6, 8 and 10 mm in diameter. GafChromic film was used for the estimation of the absorbed dose near the surface of the balloon catheters. Absorbed dose rates are plotted in units of Gy/min/GBq/ml as a function of radial distance in mm from the surface of balloon. The absorbed dose rate was 1.1, 1.6, 2.2 and 2.3 Gy/min/GBq/ml at a balloon surface, 0.3, 0.4, 0.5 and 0.6 Gy/min/GBq/ml at 1 mm depth for various balloon diameter 5, 6, 8 and 10 mm in diameter respectively. The study was conducted to estimate the absorbed doses to the vessels from various sized large balloons filled with liquid form of Ho-166-DTPA for clinical trial of radiation therapy after the PTA. The absorbed dose distribution of Ho-166 appeared to be nearly ideal for vascular irradiation since beta range is very short avoiding unnecessary radiation to surrounding normal tissues.

• Journal of Environmental Health Sciences
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• v.27 no.3
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• pp.27-34
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• 2001

This paper discussed the shape effect of ceramic support carrier in order to facilitate biomass immobilization. The shape of ceramic support carrier was modified hollow pipe type into hollow gear type. After seeding, microorganisms were attached in crevices where protection from shear forces or surfaces where easy to contact with support carrier surface. In case of hollow gear type carrier, initial attachment rate was faster than that of hollow pipe type and obtained thick biofilm. Synthetic wastewater(COD:75~880 mg/L, organic loading rate:0.36~4.22 kgCOD/㎥.d) was treated aerobic fixed bed biofilm reactor where 100% of the volume was filled with the ceramic carrier. COD removal efficiency of reactor filled with gear type support carrier was a little high withing 70 days, and then showed similar removal efficiency. It was found that highly loaded operation with up to 4.22 kgCOD/㎥.d was possible in both reactor. Total biomass amounts of pipe type was higher than gear type, however, attached biomass of gear type was higher than that of pipe type.

• Proceedings of the IEEK Conference
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• 2001.10a
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• pp.117-121
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• 2001

The present study has been conflicted to verify the applicability of tire powder and food waste compost as biofilter materials to degrade volatile organic compounds. Batch and column tests were performed to determine the optimum ratio of tire powder to compost and the appropriate mixing type of two materials for removal of the selected VOCs, i.e., benzene, ethylbenzene, PCE, and TCE. According to batch tests, tire powder and compost mixture had faster removal rate than the compost. The biofilter column filled with tire powder and compost showed better VOC removal efficiency than that filled with only tire powder. In this study, the best removal rate was observed in the sandwich type column test of which the tire : compost weight ratio was 1:2

• Proceedings of the Korean Society of Machine Tool Engineers Conference
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• 2005.05a
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• pp.264-271
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• 2005

This study investigates the behavior of fatigue crack propagating between holes or holes filled with another materials. When holes or the holes bonded with another materials exist near center crack symmetrically, crack propagation rate is influenced by the bonding force of brazing part and the elastic modulus ratio of another material to matrix. It is experimentally and analytically confirmed that the center crack stops when its tip reaches near the center line of the holes and a small crack is initiated from the boundaries of holes or the holes filled with another materials and it propagates to final fracture. The mechanical behaviors of center crack near another materials are also investigated.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.14 no.6
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• pp.74-82
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• 2005

This study investigates the behavior of fatigue crack propagating between holes or holes filled with another materials. When holes or the holes bonded with another materials exist near center crack symmetrically, crack propagation rate is influenced by the bonding force of brazing part and the elastic modulus ratio of another material to matrix. It is experimentally and analytically confirmed that the center crack stops when its tip reaches near the center line of the holes and a small crack is initiated from the boundaries of holes or the holes filled with another materials and it propagates to final fracture. The mechanical behaviors of center crack near another materials are also investigated.

• Journal of Power System Engineering
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• v.18 no.6
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• pp.174-179
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• 2014

The wear behavior of epoxy matrix composites filled with nano sized silica particles is discussed in this paper. Especially, the variation of the coefficient of friction and the specific wear rate under the various applied load and sliding velocity were investigated for these materials. Wear tests of pin-on-disc mode were carried out and followed by scanning electron microscope observations. The presence of silica filler in epoxy composites was demonstrated significant influence on the friction and wear behavior of epoxy nanocomposites. With the incorporation of silica filler into the epoxy matrix, reduction of the coefficient of friction and specific wear rate were identified. Wear mechanism was discussed by analyzing the worn surface by scanning electron microscope as well.