• Journal of Mechanical Science and Technology
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• v.16 no.4
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• pp.492-500
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• 2002

This paper presents a study of the effect of varying the roll gap of oval pass in round-oval-round pass sequence on the interracial slip of workpiece, entrance and exit velocities, stresses and roll load that the workpiece experiences during rolling, by applying analytical method, finite element simulation and verification through hot bar rolling tests. The results have shown that the roll gap variation of oval pass affects the interfacial slip of workpiece along the groove contact and the specific roll pressure. The optimum conditions in terms of minimum interfacial slip and minimum specific roll pressure, which might influence the maximum groove life, is obtained when the subsequent round pass is completely filled.

• Transactions of the Korean Society of Automotive Engineers
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• v.14 no.6
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• pp.89-94
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• 2006

The tire delivering power generated from engine to the ground pulls a vehicle to move. Radius of tires is changeable due to elasticity that depends on the speed of vehicle and traction force. The main objectives on this study are real time measurement of dynamic radius and slip ratio according to the speed and traction force. The dynamic radius is proportional to speed and traction force. According to measurement, the dynamic radius is increased about 3mm under 100km/h compared to stop. It is also increased about 1.5mm when a traction force is supplied as much as 4kN compared to no load state at low speed. There is no strong relationship between slip ratio and vehicle speed. The slip ratio is measured up to 4% under WOT at first stage gear. Through this research, the method of measuring dynamic radius and slip ratio is set up and is expected to be applied to the measurement of traction force in chassis dynamometer or accelerating and climbing ability.

• Steel and Composite Structures
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• v.45 no.5
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• pp.715-728
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• 2022

Closed steel supports of different shapes are used in mining and underground constructions. The supports are prefabricated from rolled, usually robust, steel profiles. The load carrying capacity of a support is considerably influenced by the active loading and passive forces. The passive forces are induced by interactions between the support and the surrounding rock mass. The analysis herein comprises three parts: The first part consists of structural geometry processing. The second part involves finding the numerical solution of a statically indeterminate structure for a specified load. The third part is calculation of the load carrying capacity and the components of internal forces and deformations. For this, the force method and numerical integration are used. The Winkler model is applied when the support interacts with the surrounding environment. The load carrying capacity is limited by the slip resistance of the connected parts and it is limited by reaching the ultimate state of the profile. This paper serves as a comprehensive reference for the determination of the load carrying capacity of closed steel supports and includes stepwise derivations of the governing formulas.

• Transactions of the Korean Society of Automotive Engineers
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• v.22 no.3
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• pp.1-11
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• 2014

The aim of this study is to investigate the effect of SCR reactor on the exhaust emissions characteristics in order to develop a urea-SCR aftertreatment system for reducing $NO_x$ emissions. The experiments are conducted by using a flue tube LPG steam boiler with the urea-SCR aftertreatment system. The urea-SCR aftertreatment system utilizes the ammonia converted from 17% aqueous urea solution injected in front of SCR catalyst as a reducing agent for reducing $NO_x$ emissions. The equivalence ratio, urea injection amount, ammonia slip and $NO_x$ conversion efficiency relative to boiler load are applied to discuss the experimental results. In this experiment, the average equivalence ratio is calculated by changing only the fuel consumption rate while the intake air amount is constantly fixed at $25,957.11cm^3/sec$. The average equivalence ratios are 1.38, 1.11, 0.81 and 0.57 when boiler loads are 100, 80, 60 and 40%. The $NO_x$ conversion efficiency is raised with increasing urea injection amount, and $NH_3$ slip is also boosted at the same time. Consequently, the $NO_x$ conversion efficiency relative to boiler load should be examined in combination with urea injection amount and $NH_3$ slip. The results are calculated by 89, 85, 77 and 79% for the boiler loads of 100, 80, 60 and 40%. The appropriate amount of urea injection for the respective boiler load can be not discussed by only $NO_x$ emissions, and should be determined by considering the $NO_x$ conversion efficiency, $NH_3$ slip and reactive activation temperature simultaneously. In this study, the urea amounts of 230, 235, 233 and 231 mg/min are injected at the boiler loads of 100, 80, 60 and 40%, and the final $NH_3$ slips are measured by 8.48, 5.58, 11.97 and 11.34 ppm at the same conditions. THC emission is affected by the SCR reactor under other experimental conditions except 100% engine load, and CO emission at only 40% engine load. The rest of exhaust emissions are not affected by the SCR reactor under all experimental conditions.

• Proceedings of the Korea Concrete Institute Conference
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• 2004.05a
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• pp.766-769
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• 2004

This paper presents 3D nonlinear analysis considering the slip of composite section as well as the static load tests of PSC-Steel hybrid girders. According to the slip modulus, the nonlinear analysis shows that the behavior of hybrid girders could be divided into three parts as full-composite, partial-composite and non-composite. However, the experimental results show that the PSC-Steel hybrid girders with shear connectors take the part of partial composite action in ultimate load stage. In addition, the load test results give that stud shear connectors and welded reinforcements have contributed to improve the ultimate strength of hybrid girders for about $20\%$.

• Structural Engineering and Mechanics
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• v.4 no.3
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• pp.313-329
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• 1996

A mathematical model of a cable as a system of interacting wires with interwire friction taken into account is presented in this paper. The effect of friction forces and the interwire slip on the mechanical properties of tension cables is investigated. It is shown that the slip occurs due to the twisting and bending deformations of wires, and it occurs in the form of micro-slips at the contact patches and macro-slips along the cable. The latter slipping starts near the terminals and propagates towards the middle of the cable with the increase of tension, and its propagation is proportional to the load. As the result of dry friction, the load-elongation characteristics of the cable become quadratic. The energy losses during the extension are shown to be proportional to the cube of the load and in inverse proportion to the friction force, a result qualitatively similar to that for lap joints. Presented examples show that the model is in qualitative agreement with the known experimental data.

• Tribology and Lubricants
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• v.17 no.1
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• pp.28-32
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• 2001

A new bearing concept, the wave journal bearing, has been developed to improve the static and dynamic performances of an air-lubricated hydrodynamic journal bearing. This concept features waves on bearing surface. In this study, we present the solution of the compressible Reynolds equation valid for arbitrary Knudsen numbers. Straight wave journal bearing is investigated numerically. The performances of straight wave bearing are compared to the plain journal bearing over relatively wide range of bearing number and eccentricity. The wave journal bearing offers better stability than the plain journal bearing under all bearing numbers covered in this study. The bearing load and stability characteristics are dependent on the geometric parameters such as the amplitude and the starting point of the wave relative to the applied load. Under the condition of Knudsen number＞0.01, we can not ignore the effect of slip for Journal bearing.

• Structural Engineering and Mechanics
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• v.83 no.1
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• pp.109-121
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• 2022

Twelve push-out test specimens were conducted with various parameters to study the static and fatigue performance of a new through-bolt shear connector transferring the shear forces of interface between prefabricated hybrid fiber reinforced concrete (HFRC) slabs and steel girders. It was found that the fibers could improve the fatigue life, capacity and initial stiffness of through-bolt shear connector. While the bolt-hole clearance reduced, the initial stiffness, capacity and slippage of through-bolt shear connector increased. After the steel-concrete interface properties were improved, the initial stiffness increased, and the capacity and slippage reduced. Base on the test results, the equation of the load-slip curve and capacity of through-bolt shear connector with prefabricated HFRC slab were obtained by the regression of test results, and the allowable range of shear force under fatigue load was recommended, which could provide the reference in the design of through-bolt shear connector with prefabricated HFRC slabs.

• Transactions of the Korean Society of Automotive Engineers
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• v.17 no.3
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• pp.74-80
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• 2009

The objective of this paper was to investigate the slip rate and the slip frequency number of damper clutch of torque converter in 2.4L passenger vehicle with 5-speed A/T and analyze the effect of slip control and control strategy on driving characteristics and the fuel economy. The newly developed torque converter with the more durable wet friction material and the slip-controlled damper clutch system, the DCC system, was installed, which was easily compatible and amendable of the lock-up clutch of the base system. The vehicle has been tested on the fuel economy modes such as FTP-75, HWFET and NEDC (ECE15+EUDC) driving cycle at chassis dynamometer. The DCC mode (II), of which the control strategy had both the lock-up and the slip-controlled clutch, and the DCC mode (I) with full slip-controlled clutch were compared with the base system with only the lock-up clutch. As the research result, comparison to base system, the fuel consumption of the vehicle with the DCC control (II) was effectively improved by 6.6% and 7.7% on FTP-75 and NEDC mode.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.22 no.1
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• pp.105-115
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• 2009

Numerical analysis of shear walls governed by flexural behavior is conducted for the seismic control performance of proposed friction dampers installed at the center of coupling beams. Control effectiveness of shear walls connected by beams with the proposed dampers are compared for single shear wall with same flexural rigidity. Average responses of the shear walls with the dampers are found with seven scaled-downed earthquakes based on KEC 2005 design spectrum. Slip load is the most important design parameter. It is designed to be 5, 10, 20, 30, 60, 90% of total vertical shear force at damper location to prevent damper slip in specific stories. Nonlinear time-history analysis is conducted by using SeismoStruct analysis program. Seismic control performance of the dampers is evaluated for base shear, energy dissipation, curvature and top-floor displacement. Results show that the dampers are the most effective in reducing the responses when their total slip load is 30% of total vertical shear force.