• Tribology and Lubricants
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• v.30 no.2
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• pp.108-115
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• 2014

The friction behaviors of bulk amorphous thermal spray coating (BAC) and second phase-reinforced composite coatings using a high velocity oxy-fuel spraying process were investigated using a ball-on-disk test rig that slides against a ceramic ball in an atmospheric environment. The surface temperatures were measured using an infrared thermometer installed 50 mm from the contact surface. The crystallinities of the coating layers were determined using X-ray diffraction. The morphologies of the coating layers and worn surfaces were observed using a scanning electron microscope and energy-dispersive spectroscopy. The results show that the friction behavior of the monolithic amorphous coating was sensitive to the testing conditions. Under lower than normal loads, a low and stable friction coefficient of about 0.1 was observed, whereas under a higher relative load, a high and unstable friction coefficient of greater than 0.3 was obtained with an instant temperature increase. For the composite coatings, a sudden increase in friction coefficient did not occur, i.e., the transition region did not exist and during the friction test, a gradual increase occurred only after a significant delay. The BAC morphology observations indicate that viscous plastic flow was generated with low loads, but severe surface damage (i.e., tearing) occurred at high loads. For composite coatings, a relatively smooth surface was observed on the worn surface for all applied loads.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1991.10a
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• pp.69-72
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• 1991

The purpose of this study is to develop the reliability-based dynamic load model for bridges. Analytial procedure to calculate the dynamic load is developed. Truck traffic is simulated using Monte Carlo method. Static and dynamic loads(deflections) are plotted on the normal probability paper to estimate the mean maximum dynamic load in bridge lifetime. The results may be served as a basis for new LRFD bridge design code.

• Proceedings of the Korea Concrete Institute Conference
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• 1999.10a
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• pp.521-524
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• 1999

Twelve column specimens were tested in compression, six were slab-column specimens and six were isolated column specimens. The slab column specimens were first tested to punching shear failure before the columns of the specimens were loaded axially. The effects of confinement from the surrounding slab on the axial capacity of the columns was investigated. Other parameters investigated were the placement of fiber-reinforced concrete in the slab and the concentration of flexural reinforcement in the column vicinity.

• Tribology and Lubricants
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• v.12 no.1
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• pp.6-14
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• 1996

Experimental investigation on the tribological behavior of fiber-reinforced plastics(FRP) has been studied. It is shown that the frictional behavior of carbon FRP depends on the fiber-orientation while glass FRP does not. The friction coefficient values for carbon FRP were about 0.8, 0.3, and 0.2 for normal, 45$^{\circ}$ and 0$^{\circ}$ sliding directions respectively. Also, the applied load was found to affect the friction coefficient. In the case of this work, 50 gf resulted in the highest value while 200 gf resulted in the lowest value. The friction coefficients for higher loads fell in between the two extreme values.

• Tribology and Lubricants
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• v.18 no.6
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• pp.418-424
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• 2002

The basic concept of ‘gear profile modification’ is to change a part of the involute profile to reduce the load in that area and appropriate profile modifications can help gears to run quietly and resist scoring., pitting, and tooth breakage. In this study, the modification of tooth profile to make a smooth transmission of the normal loads in spur gears has been developed. The modified tooth profile has been determined by the total deflection at contact points. We also compared our results with other experimental results.

• Journal of Aerospace System Engineering
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• v.10 no.2
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• pp.22-26
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• 2016

Whole airplane recovery parachute system(WARPS) is a auxiliary safety system to protect occupants in emergency situation where recovery to normal flight condition is impossible. In this paper, application and certification cases of WARPS for Part 23 small airplane is introduced and considerations in certification of the WARPS installed airplane are provided in terms of performance of parachute, function and operation, loads and strength and protection of occupants.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1998.10a
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• pp.144-148
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• 1998

Using a test apparatus developed Lrt the laboratory, frictional characteristics of natural rubbers have been analyzed by experimental study. Friction coefficient has been calculated from the measured normal force and friction force under various speeds, loads, and temperatures. The relations between the various operating conditions and friction coefficients have been verified. Especially, drag friction due to the visco-elastic behavior of the rubber has been observed in this analysis.

• Proceedings of the KSME Conference
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• 2000.11a
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• pp.426-431
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• 2000

A decoupled thermo-piezoelectric-mechanical model of composite laminates with surface bonded piezoelectric actuators, subjected to externally applied load, temperature change load, electric field load is developed. The governing differential equations are obtained by applying the principle of free energy and variational techniques. A higher order zigzag theory displacement field is employed to accurately capture the transverse shear and normal effects in laminated composite plates of arbitrary thickness.

• Proceedings of the Korea Concrete Institute Conference
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• 1992.04a
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• pp.53-58
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• 1992

This research is related to the experimental investigation of the inelastic behavior of R/C columns with high strength concrete. A total of eight specimens have been tested with different span ratios, steel reinforcements and load applications. Through tests bending moments were applied incrementally while axial forces being kept constantly at 80 tons. Careful observation were given to initial crack formation, crack patterns and propagation paths. Comparative studies have been made on the load carrying capacity for R/C columns with high strength concrete versus normal strength concrete.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.20 no.43
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• pp.197-204
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• 1997

Torques on each joint, the compression on L5/S1 disc, the force on hand of a rider are estimated using a static biomechnic model. Forces that the rider applies to the pedals, saddle and handle during starting and speeding are estimated using static mechanics. Physical stress is considered accroding to handle height and horizontal distance between handle and pedal. When handle height is higher in normal speeding, the force on handle and sum of torques on each joint decreases.