• Fibers and Polymers
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• v.2 no.4
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• pp.184-189
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• 2001

Continuous photografting/crosslinking of polyethyleneglycol dimethacrylate oligomers onto cotton using a water-soluble benzophenone photoinitiator was investigated. Photografting increased with increasing irradiation dose, oligomer concentration and photoinitiator concentration. Maximum grafting efficiency of DM 400 and 600 were 83% and 79%, respectively. the photografting increased the wrinkle resistance of cotton implying surface crosslinking of cotton. bothsurface crosslinking and bulk crosslinking of cotton were accomplished via dual curing of a mixed formulation containing both a thermally curable component (BTCCA/SHP) and a UV-curable component. The wrinkle resistance of the crosslinked cotton was found to be higher when cured by thermal curing due to the facile post-polymerization of the UV active component. The presence of crosslinks in the dually crosslinked cotton was verified with FT-IR and thermogravimetric analysis.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.357-362
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• 2000

Allowable stress design(ASD) method has been widely used to design steel structures such as boiler and heat recovery steam generator(HRSG) of power plant. However, many researchers are recently intrested in road and resistance factor design(LRFD) method which may take the place of ASD. In this work, the weight calculation of steel structure was compared when ASD and LRFD were applied respectively. For the calculation of weight of steel structure, computer program was developed and applied to obtain beam weight. Using this program and GTSTRUDL, structural design program, weight of steel structure is calculated. As a result of weight calculation, maximum 5.4% of weight reduction is achieved among examples of this study by applying LRFD comparing with the result of ASD, and those results quite dependent on the applied load and member classification.

• Transactions of the Korean Society of Automotive Engineers
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• v.5 no.2
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• pp.1-12
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• 1997

A computer program was developed to simulate effect of the initial track tension on the tractive performance of tracked vehicles. The performance was evaluated in terms of drawbar pull, motion resistance, tractive coefficient and tractive efficiency. Results of the simulation showed that increase in track tension decreases the sinkage and mean maximum pressure in clay, making the ground pressure distribution more uniform. This tendency became more evident when the number of roadwheels increased. However, such change in MMPs was negligible in firm soils. Motion resistance was also decreased with increase in track tension and the number of roadwheels. Under weak soil conditions, tractive coefficient and efficiency increased generally as the track tension increased for a slip range of 10∼30%. For slippage less than 3∼4%, however, the tractive coefficient decreased with increase in track tension. In general, it was known that increasing track tension improves tractive performance in weak soil conditions. However, high track tension can reduce efficiency due to the increment of internal motion resistance caused by increased track tension.

• Geotechnical Engineering
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• v.3 no.3
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• pp.31-48
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• 1987

The vertical pressure due to soil prism load and surface surcharge load acts on buried pipe, and occasionally uplifting force due to earthquake or differential settlement acts on it. In this paper, study was performed to estimate the pressure acting on the buried pipe due to soil prism load through analyzing Marston-Spangler theory by new method. And loading tests on the buried flexible pipe were performed to study on the response of the pipe due to surface surcharge load. Also, through the estimation of uplifting resistance theory and uplifting test for buried pipe, the method to determine the maximum uplifting resistance of buried pipe was proposed.

• Journal of the Korean Ceramic Society
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• v.37 no.3
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• pp.201-204
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• 2000

Thermal shock resistance of 80Al2O3-20Al composite and monolithic alumina ceramics was compared. Fracture strength was measured by using a 4-pont bending test after quenching. Thermal stresses of the ceramics and ceramic-metal composites were calculated using a finite element analysis. The bending strength of the Al2O3 ceramics decreased catastropically after quenching from 20$0^{\circ}C$ to $0^{\circ}C$. The bending strength of the composite also decreased after quenching from 200~2$25^{\circ}C$, but the strength reduction was much smaller than for Al2O3. The maximum thermal stress occured in the monolithic alumina ceramics when exposed to a temperature difference of 20$0^{\circ}C$ was 0.758 GPa. The same amount of stress occured in the Al2O3-Al composite when the temperature difference of 205$^{\circ}C$ used.

• Geomechanics and Engineering
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• v.5 no.4
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• pp.299-312
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• 2013

The horizontal pullout capacity of a group of two vertical strip plate anchors, placed along the same vertical plane, in a fully cohesive soil has been computed by using the lower bound finite element limit analysis. The effect of spacing between the plate anchors on the magnitude of total group failure load ($P_{uT}$) has been evaluated. An increase of soil cohesion with depth has also been incorporated in the analysis. For a weightless medium, the total pullout resistance of the group becomes maximum corresponding to a certain optimum spacing between the anchor plates which has been found to vary generally between 0.5B and B; where B is the width of the anchor plate. As compared to a single plate anchor, the increase in the pullout resistance for a group of two anchors becomes greater at a higher embedment ratio. The effect of soil unit weight has also been analyzed. It is noted that the interference effect on the pullout resistance increases further with an increase in the unit weight of soil mass.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.24 no.10
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• pp.85-89
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• 2010

During a ground fault the maximum fault current and neutral to ground voltage will appear at the pole nearest to the fault. Distribution lines are consisted of three phase conductors, an overhead ground wire and a multi-grounded neutral line. In this paper phase to neutral faults were staged at the specified concrete pole along the distribution line and measured the ground fault current distribution in the ground fault current, three poles nearest to the fault point, overhead ground wire and neutral line. A effect by grounding resistance of poles of ground fault current in the 22.9[kV] multi-ground distribution system. by field tests.

• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
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• 2003.05c
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• pp.261-264
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• 2003

In this paper, a disk-type piezoelectric transformer for the high power was investigated with the variation of road resistance. The diameter and thickness of a disk-type piezoelectric transformer was 45mm and 4mm, respectively. The piezoelectric ceramics was composed to PZT-PMN-PSN. The ratio of driving electrode and generating electrode is 2:1. The poling direction of driving part and generating part are the same. A voltage step-up ratio increased with increasing the load resistance, $R_L$, so it reached 60 under no road resistance. Also, the maximum efficiency of 97% was obtained.

• Proceedings of the KIEE Conference
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• 2003.07c
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• pp.1490-1492
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• 2003

A new type of piezoelectric transformer using radial vibration of disk, poled with the same direction is proposed. The piezoelectric ceramics was composed to PZT-PMN-PSN. The surface ratio of driving electrode and generating electrode of the piezoelectric transformer ranges from 1.4:1 to 3:1. As a experimental result, both resonance frequency and step-up voltage ratio increased with increasing load resistance. The step-up voltage ratio was reached more than 60 times under no load resistance. The maximum efficiency of 97.7% at load resistance of 2k${\Omega}$ was obtained.

• Journal of the Korean Graphic Arts Communication Society
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• v.18 no.2
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• pp.83-101
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• 2000

In this experiment butadiene rubber(BR)/acrylonitrile butadiene rubber(NBR) blends was prepared and then the applicability of BR/NBR blends as printing rubber roller was examined. With the aid of open 2-roll mill, BR, NBR and another chemical additives were compounded. Then rubber vulcanizates were manufactured by hot press and maximum torque, Mooney viscosity, mechanical properties and oil resistance of the test specimens were measured. With prolonged oil aged treating time, BR/NBR blends became soft and so the hardness of blends decreased. It could be explained by the swelling of rubber matrix with oil penetration in to rubber molecules. The undesirable low value of oil resistance of BR was significantly improved by blending BR with NBR.