• Journal of the Korean Society of Safety
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• v.14 no.4
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• pp.3-12
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• 1999

This research concentrates on the influence of non-linearities associated with impact for the nonlinear rocking behavior of rigid block subjected to one dimensional sinusoidal excitation of horizontal direction. The transition of two governing rocking equations, the abrupt reduction in the kinetic energy associated with impact, and sliding motion of block. In this study, two type of rocking vibration system are considered. One is the undamped rocking vibration system, disregarding energy dissipation at impact and the other is the damped rocking system, including energy dissipation and sliding motion. The response analysis using non-dimensional rocking equation is carried out for the change of excitation parameters and friction coefficient. The chaos responses were discovered in the wide response region, particularly, for the case of high excitation amplitude and their chaos characteristics were examined by the time history, Poincare map, power spectra and Lyapunov Exponent of rocking responses. The complex behavior of chaos response, in the phase space, were illustrated by Poincare map. The bifurcation diagram and Poincare map were shown to be effective in order to understand chaos of rocking system.

• Transactions of the Korean Society of Machine Tool Engineers
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• v.13 no.5
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• pp.16-23
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• 2004

The wear behavior as the hardness of the sliding elements on the dry wear has been investigated using a disc on disc configuration. The materials of the specimens are used as ten kinds along their hardness. In this study, both upper and lower specimens have been used the same materials. Using experimental data, we figured the relationship between wear coefficient and friction coefficient, and the relationship between wear coefficient and friction temperature. Also we combined friction temperature and friction coefficient instead of wear coefficient. We substituted this into wear equation of Archard. The result had been derived a newly wear equation in disc on disc wear system.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 1991.04a
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• pp.84-90
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• 1991

Underground structures usually consist of rock masses or concretes which can be cracked or have cracks. This study aims to develop an analysis program which can deal with the effect of discontinuous behavior due to those cracks using the block theory. It is assumed that rock masses form blocks along the discontinuity lines, and deformation within the block is relatively small. The behavior of discontinuity plane of the structures is divided into sliding along the discontinuity plane. separation of discontinuity by tensile force, and degradation of asperity angle of discontinuity plane by external force with sliding of rock Basses. These behaviors are implemented using constitutive relation and relevent load-displacement relation defined through normal and shear stiffnesses. Time varying displacements and block velocities are calculated by explicit time stepping algorithm. The effect of rock supports including rockbolts is also considered, and the tending effects which occurs in relatively thin lining is also considered.

• Carbon letters
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• v.10 no.2
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• pp.97-100
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• 2009

In this work, effects of carbon matrix on sliding friction and wear behavior of four kinds of C/C have been investigated against 40 Cr steel ring mate. Composite A with rough lamination carbon matrix (RL) shows the highest volume loss and coefficient of friction, while composite D with smooth lamination/resin carbon matrix (SL/RC) shows the lowest volume loss. The worn surface of composite A appears smooth, whereas that of composite C with smooth lamination carbon (SL) appears rough. The worn surface of composite D appears smooth under low load but rough under high load. Atomic force microscope images show that the size of wear particles on the worn surface is also dependent on the carbon matrix.

• Geotechnical Engineering
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• v.12 no.5
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• pp.55-62
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• 1996

Lateral loading model tests were performed on the rigid box-shaped cellular bulkhead by displacement-controlled method. The materials of ground and fill used in this study are two aluminium rods with different sections. The behalf·iotas of ground and fill were recorded by photo/video techniques and failure mechanism created in ground and fill has been simulated two-야mensionally. Also the theoretical consideration about the test results was done on the basis of Hansen's earth pressure theory. As a result, the shape of sliding face the location of sliding face and the loading height was also investigated.

• Journal of Powder Materials
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• v.13 no.6 s.59
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• pp.450-454
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• 2006

Wear of steel plate was measured during unlubricated sliding against TiC composites. These composites consist of round TiC grains and steel matrix. TiC grain itself exhibits low surface roughness and round shape, which does not bring its counterpart into severe damage from friction. In our work a classical experimental design was applied to find out a dominant factor in counterpart wear. The analysis of the data showed that only the applied load has a significant effect on the counterpart wear. Wear rate of counterpart increased non-linearly with applied load. Amount of wear was discrepant from expectation of being in proportion to the load by analogy with friction force. Our experimental result from treating matrix variously revealed bimodal wear behavior between the composites and counterpart where a mode seems to result from the special lubricant characteristic of TiC grains, and the other is caused by metal-to-metal contact. The two wear mechanisms were discussed.

• Journal of KSNVE
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• v.7 no.2
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• pp.239-246
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• 1997

This paper presents an active suspension control algorithm to improve the suspension performance trade-offs between riding comfort and handling stability. In this paper, a hybrid control scheme is proposed, the idea of which is that sliding mode control is used for nonlinear hydraulic system and the skyhook control is applied to control the vehicle behavior. The parameter variations in hydraulic system are considered for the robust controller design. The performance of the proposed control method is evaluated by simulation and experiments based on a half car roll model which can reveal both heave and roll behavior.

• Journal of the Korean Geotechnical Society
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• v.16 no.6
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• pp.153-160
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• 2000

본 연구는 과제하중의 재하폭과 재하위치를 매개변수로 변화시켜 옹벽의 뒤채움재 상부 지표면에서 제한폭의 과재하중작용시 그의 활동거동에 관한 실험적, 수치적 해석적 연구이다. 중력 수준을 1g, 20g,40g로 변화시켜 수행한 원심모형실험을 통해 구한 기초의 극한지지력 및 하중-침하특성, 하중-옹벽수평변위특성에 관하여 조사연구 하였다. 또한, 옹벽의 활동으로 인한 지반파괴의 영향을 받기 시작하는기초의 재하위치를 추정하기 위하여 종래의 얕은 기초의 극한지지력 실험을 수행하여 이들 결과와 함께 비교하였다. 한편, 모형실험결과와 기존의 이론식을 수정보완한 해석 결과와 비교분석하였다.

• Steel and Composite Structures
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• v.1 no.2
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• pp.201-212
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• 2001

In order to investigate the effect of the loading rate on the mechanical behavior of SRC shearwalls, we conducted the lateral loading tests on the 1/3 scale model shearwalls whose edge columns were reinforced by H-shaped steel. The specimens were subjected to the reversed cyclic lateral load under a variable axial load. The two types of loading rate, 0.01 cm/sec for the static loading and 1 cm/sec for the dynamic loading were adopted. The failure mode in all specimens was the sliding shear of the in-filled wall panel. The edge columns did not fail in shear. The initial lateral stiffness and lateral load carrying capacity of the shearwalls subjected to the dynamic loading were about 10% larger than those subjected to the static loading. The effects of the arrangement of the H-shaped steel on the lateral load carrying capacity and the lateral load-displacement hysteresis response were not significant.

• Tribology and Lubricants
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• v.36 no.3
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• pp.124-132
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• 2020

The effect of the stoichiometry on the sliding wear properties of NiAl coatings has been investigated. Three different powder mixtures with the compositions of Ni-50at%Al, Ni-54at%Al and Ni-42at%Al were diepressed respectively, and which were subsequently coated on mild steel through combustion synthesis in an induction heating system. Sliding wear behavior of the coatings was examined against an alloyed tool steel using a pin-on-disc type sliding wear test machine. As results, it could be seen that powder mixture(Ni-54at%Al) with displaying Al-rich deviations from the stoichiometry of NiAl(Ni-50at%Al) was promoted the most the synthetic reactivity. The microstructure of the coating layer with the compositions of Ni-54at%Al exhibits the porous NiAl single phase structure. However, the microstructure of the coating layer of the compositions of Ni-42at%Al exhibits the denser multi-phase structure containing several intermediate phases in addition to NiAl. Densification of the coating layer was enhanced by increasing the reacting temperature. On the other hand, the wear properties of the coating layers showed that the wear mode at speeds of around 1 m/s was severe wear, regardless of the stoichiometry and reacting temperature. However, wear properties of coating layer with the compositions of Ni-42at%Al were superior to those of coating layer with the compositions of Ni-54at%Al. This would be attributed by the fact that coating layer with the compositions of Ni-42at%Al develops little void and much intermediate phases with high strength.