• Journal of the Korea Academia-Industrial cooperation Society
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• v.15 no.7
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• pp.4469-4474
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• 2014

This paper proposes a novel analysis method on the driving performance of LIM (linear induction motor) by FEM (finite element method). First, a linear model was converted with a rotation model to perform the dynamic analysis for a long time. Through the FEM model, the slip parameter for the control algorithm could be induced effectively. The LIM for the traction system was performed at a constant V/f in the region of constant torque, and a constant V and variable f in the region of constant power. Several slip characteristic curves according to the voltage and frequency were calculated by FEM in advance. The driving performance was then induced by interpolating the slip characteristic curves according to the load of the vehicle.

• Tunnel and Underground Space
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• v.26 no.1
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• pp.12-23
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• 2016

For a successful accomplishment of Carbon Capture Sequestration (CCS) projects, appropriate injection conditions should be designed and optimized for site specific geological conditions. In this study, we evaluated the effect of injection conditions such as injection temperature and injection rate on the geomechanical stability of CCS system in terms of TOUGH-FLAC simulator, which is one of the well-known T-H-M coupled analysis methods. The stability of the storage system was assessed by a shear slip potential of the pre-existing fractures both in a reservoir and caprock, expressed by mobilized friction angle and Mohr stress circle. We demonstrated that no tensile fracturing was induced even in the cold CO2 injection, where the injected CO2 temperature is much lower than that of the reservoir and tensile thermal stress is generated, but shear slip of the fractures in the reservoir may occur. We also conducted a scenario analysis by varying injected CO2 volume per unit time, and found out that it was when the injection rate was decreasing in a step-wise that showed the least potential of a shear slip.

• Corrosion Science and Technology
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• v.11 no.2
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• pp.48-55
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• 2012

Clamping force of a high strength bolt is reduced by a certain period of time after the initial set-up. In case of special treatments on faying surfaces such as protective coating, clamping force is relaxed more severely. Tests for slip critical joints subject to various faying surface parameters were conducted. Five different surface treatments were tested including mill scale surface, blast surface, rust surface and coated surfaces. Each specimen was composed of F10T M20 of high strength bolts and steel plates. Based on the result of slip coefficient test, blast treatment surface showed 0.59, rust treatment surface showed 0.54 and inorganic zinc treatment surface exhibited 0.44. Clean mill treatment surface and red lead paint treatment surface were 0.23, 0.21 respectively. It is identified that the slip coefficient in Korean structural design guide should be determined for various surface conditions. Subsequently from long term relaxation test of ASTM A 490 high strength bolts, relaxation of no-coated surfaces such as blast, clean mill, rust treatment, the loss of initial clamping load was 10.5%, 13.6% and 7.9% for 1,000 hours, while the loss of initial clamping force was reached as 15.0%, 18.7% more than the required redundancy 10% in case of inorganic zinc and red lead painted treatment. It is required that the limit of relaxation on coated faying surface should be established separately for various surfaces.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.11
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• pp.1979-1985
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• 2003

Fretting is a kind of surface degradation mechanism observed in mechanical components and structures. The fretting damage decreases in 50-70% of the plain fatigue strength. This may be observed in the fossil power plant and the nuclear power plant used in special environments and various loading conditions. The thermal degradation of material is observed when the heat resisting steel is exposed for long period time at the high temperature. In the present study, the degraded 1Cr-0.5Mo steel used for long period time at high temperature (about 515$^{\circ}C$) and artificially reheat-treated materials are prepared. These materials are used for evaluating an effect of thermal aging on the fretting fatigue behavior. Through the experiment, it is found that the fretting fatigue endurance limit of the reheat-treated 1Cr-0.5Mo steel decreased about 46% from the non-fretting fatigue endurance limit, while the fretting fatigue endurance limit of the degraded 1Cr-0.5Mo steel decreased about 53% from the non-fretting fatigue endurance limit. The maximum value of fatigue endurance limit difference is observed as 57%(244 MPa) between the fretting fatigue of degraded material and non-fretting fatigue of reheat-treated material. These results can be a basic data to a structural integrity evaluation of heat resisting steel considered to thermal degradation effect.

• The Journal of Engineering Geology
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• v.32 no.4
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• pp.467-482
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• 2022

The Yeonghae basin is located at the northeastern part of the Yangsan fault (YSF; a potentially active fault). The study of the architecture of the Yeonghae basin is important to understand the activity of the Yangsan fault system (YSFS) as well as the basin formation mechanism and the activity of the YSFS. For this study, Digital Elevation Model (DEM) was used to highlight the marginal faults, and structural fieldwork was performed to understand the geometry of the intra-basinal structures and the nature of the bounding faults. DEM analysis reveals that the eastern margin is bounded by the northern extension of the YSF whereas the western margin is bounded by two curvilinear sub-parallel faults; Baekseokri fault (BSF) and Gakri fault (GF). The field data indicate that the YSF is striking in the N-S direction, steeply dipping to the east, and experienced both sinistral and dextral strike-slip movements. Both the BSF and GF are characterized dominantly by an oblique right-lateral strike-slip movement. The stress indicators show that the maximum horizontal compressional stress was in NNE to NE and NNW-SSE, which is consistent with right-lateral and left-lateral movements of the YSFS, respectively. The plotted structural data show that the NE-SW is the predominant direction of the structural elements. This indicates that the basin and marginal faults are mainly controlled by the right-lateral strike-slip movements of the YSFS. Based on the structural architecture of the Yeonghae basin, the study area represents a contractional zone rather than an extensional zone in the present time. We proposed two models to explain the opening and developing mechanism of the Yeonghae basin. The first model is that the basin developed as an extensional pull-apart basin during the left-lateral movement of the YSF, which has been reactivated by tectonic inversion. In the second model, the basin was developed as an extensional zone at a dilational quadrant of an old tip zone of the northern segment of the YSF during the right-lateral movement stage. Later on, the basin has undergone a shortening stage due to the closing of the East Sea. The second model is supported by the major trend of the collected structural data, indicating predominant right-lateral movement. This study enables us to classify the Yeonghae basin as an inverted strike-slip basin. Moreover, two opposite strike-slip movement senses along the eastern marginal fault indicate multiple deformation stages along the Yangsan fault system developed along the eastern margin of the Korean peninsula.

• Proceedings of the Korea Association of Crystal Growth Conference
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• 1997.06a
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• pp.41-44
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• 1997

Dispersion and flocculation behaviors of clay-ash powders in a slurry state were examined, and we have systematically investigated the effects of colloid/interfaces variables on slip properties and the rheological behavior of ash-clay slurry. Ash-clay slurries have been characterized on the basis of the time dependent rheology which was done out by the gel-curve test. Gel-curve for the coagulated slip shows interesting rheological behavior which was caused by the formation of the new network structure and the readsoption of the polysilicon hydroxo species on the particle surfaces.

• 제어로봇시스템학회:학술대회논문집
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• 2004.08a
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• pp.990-994
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• 2004

This paper presents a method to predict the transient characteristic of the air lubricated slider head in a hard disk drive by using optimization technique. The time dependent modified Reynolds equation based on the molecular slip flow approximation equations was used to describe the fluid flow within the air bearing and the implicit finite difference scheme is applied to calculate the pressure distribution under the slider head. The exhaustive search combined with the Broyden-Fletcher-Goldfarb-Shanno method were employed to obtain optimum design variables which are taper angle, rail width and taper length in order to keep the forces and moments acting on the slider head in dynamic equilibrium. The results show that the optimal head slider of the magnetic head has good stability characteristic that can reach the steady state within 0.5 microsecond.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2002.03a
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• pp.28-35
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• 2002

The probabilistic seismic hazard analysis for engineering needs several active fault parameters as input data. Fault slip rates, the segmentation model for each fault, and the date of the most recent large earthquake in seismic hazard analysis are the critical pieces of information required to characterize behavior of the faults. Slip rates provide a basis for calculating earthquake recurrence intervals. Segmentation models define potential rupture lengths and are inputs to earthquake magnitude. The most recent event is used in time-dependent probability calculations. These data were assembled by expert source-characterization groups consisting of geologists, geophysicists, and seismologists evaluating the information available for earth fault. The procedures to prepare inputs for seismic hazard are illustrated with possible segmentation scenarios of capable fault models and the seismic hazards are evaluated to see the implication of considering capable faults models.

• Transactions of the Korean Society of Automotive Engineers
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• v.6 no.3
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• pp.45-53
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• 1998

Traction control systems(TCS) improve vehicle acceleration performance and stability, particularly on slippery roads through engine torque and/or brake torque control. This research mainly deals with the engine control algorithm based on adjustment of the engine throttle valve opening. Hardware-in-the-loop simulation(HWILS) is carried out where the actual hardware is used for the engine/automatic transmission and TCS controller, while various vehicle dynamics are simulated on real-time basis. Also, use of the dynamometer is made in order to implement the tractive force that a road applies to the tire. Although some restrictions are imposed mainly due to the capability of the synamometer, simplified HWILS results show that the slip control algorithm can improve the vehicle acceleration performance for low-friction roads.

• Transactions of the Korean Society of Automotive Engineers
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• v.10 no.3
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• pp.201-208
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• 2002

In this paper, the control strategy of ratio changing system for a metal belt CVT adopting primary pressure regulation is developed, and the shirting performance of pressure regulating type CVT with the suggested control strategy is investigated. The control strategy suggested in this study is composed of 2 feedback loop, one is speed ratio feedback and the other is primary pressure feedback. The pressure feedback is adopted to ensure prohibiting a belt slip during transient period in a fast downshift mode. Simulation results show that the system with suggested control strategy gives appropriate response time and tracking Performance for upshift and also gives a proper primary pressure which can prohibit the belt slip. In addition, it is fecund that the given system has an acceptable servo property in tracking the target speed ratio and robustness for the disturbance of line pressure.