• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.12
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• pp.880-887
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• 2020

This study was conducted to investigate the running stability of a high-speed train operated in a tunnel and an open field when external forces such as wind pressure and train crossings were applied to the vehicle. With no external force, the running stability at 400 km/h was examined, and the wheel weight reduction ratio, lateral pressure of the axles, and derailment coefficient satisfied the criteria of the technical standards for a high-speed train. When the distance between the centers of the tracks is 4.6 m, the external force caused by train crossing slightly affects the lateral acceleration of the vehicle but does not significantly affect the wheel weight reduction rate, lateral pressure, and derailment coefficient in a tunnel and open filed. When the distance is 4.6~5.0 m, the wheel weight reduction ratio, lateral pressure, and derailment coefficient satisfy the criteria with 20 m/s wind. When the wind speed was 30 m/s, the derailment coefficient satisfied the criteria, and the other variables exceeded them. It is predicted that a high-speed train can be operated safely at 400 km/h with wind speed of up to 20 m/s, and it should be slowed down at a wind speed of 30 m/s.

• Geotechnical Engineering
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• v.1 no.2
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• pp.27-40
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• 1985

This study aims at the development of computer Program for the deformation analysis of soft clay layers, and using this computer program, study the constraint effect of deformation- heaving, lateral displacement-of the soft clay layers reinforced with sheet pile at the tip of banking or improvement of soft clay layer up to hard strata, under intact state (natural) and the state of vertical drain respectively. For this study, Biot's consolidation theories and modified Cam-clay theory for constitutive equation for FEMI were selected and coupled governing equation, and christian-Boehmer's technique was applied to solve the coupled relationship. The following results are obtained. 1. Sheet pile or improvement of soft clay layer to the hard strata work well against the settlement of neighboring ground. B. In view of restriction of heaving or lateral displacement, sheet pile is not supposed to be of use. 3. Sheet pile is of effect only when vertical drain is constructed for acceleration of consolidation and load increases gradually. B. The larger the rigidity of improvement of layer to hard strata is, the less settlement occurs.

• Korean Journal of Applied Biomechanics
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• v.14 no.3
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• pp.149-163
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• 2004

This study analyzed kinematic variables about the cross step, the delivery and the release for women's javelin athletics recorded over 50m in the 2004 Busan International Athletics Competition. It was used the Kwon3D Motion Analysis Package Ver. 3.1 Program(Kwon, 2000) for analysing the kinematic variables about the distance, the velocity, and the angle, then we had the results as follows; 1 In the Cross step phase, the COG velocity was low because their step length was short. To keep the CM velocity from the approach to the last cross over step contact, the athletes have to keep the longer step length within about 130% of the athletics' height. 2. In the Delivery phase, the athletics' COG height was gradually lower, and the deceleration of the COG was going up. As the same in the cross step, Therefore the athletes have to increase the step length within about 100% of their height, in order to increasing the COG velocity. And it was shown they have to make small angle of the elbow as possible from the right foot contact to the left foot contact in order to being the big acceleration of the upperarm at the release phase. 3. In the release phase, it was shown to being low position of the release point as the COG was low and then the release velocity of the upperarm was low. Specially when the shoulder lean lateral angle is big at the release phase, it was shown they have a excessive release angle. And, when it was shown the high rotation angle of the shoulder, the shoulder was opened forward bigger than the trunk was opened forward. So the transmission of velocity from the proximal segments was a fast change.

• Journal of Advanced Navigation Technology
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• v.11 no.4
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• pp.359-370
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• 2007

Lane tracking and obstacle avoidance are considered two of the key technologies on an unmanned ground vehicle system. In this paper, we propose a method of lane tracking and obstacle avoidance, which can be expressed as vehicle control, modeling, and sensor experiments. First, obstacle avoidance consists of two parts: a longitudinal control system for acceleration and deceleration and a lateral control system for steering control. Each system is used for unmanned ground vehicle control, which notes the vehicle's location, recognizes obstacles surrounding it, and makes a decision how fast to proceed according to circumstances. During the operation, the control strategy of the vehicle can detect obstacle and perform obstacle avoidance on the road, which involves vehicle velocity. Second, we explain a method of lane tracking by means of a vision system, which consists of two parts: First, vehicle control is included in the road model through lateral and longitudinal control. Second, the image processing method deals with the lane tracking method, the image processing algorithm, and the filtering method. Finally, in this paper, we propose a method for vehicle control, modeling, lane tracking, and obstacle avoidance, which are confirmed through vehicles tests.

• Earthquakes and Structures
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• v.11 no.2
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• pp.195-215
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• 2016

Rehabilitation of historical unreinforced masonry (URM) buildings is a priority in many parts of the world, since those buildings are a living part of history and a testament of human achievement of the era of their construction. Many of these buildings are still operational; comprising brittle materials with no reinforcements, with spatially distributed mass and stiffness, they are not encompassed by current seismic assessment procedures that have been developed for other structural types. To facilitate the difficult task of selecting a proper rehabilitation strategy - often restricted by international treaties for non-invasiveness and reversibility of the intervention - and given the practical requirements for the buildings' intended reuse, this paper presents a practical procedure for assessment of seismic demands of URM buildings - mainly historical constructions that lack a well-defined diaphragm action. A key ingredient of the method is approximation of the spatial shape of lateral translation, ${\Phi}$, that the building assumes when subjected to a uniform field of lateral acceleration. Using ${\Phi}$ as a 3-D shape function, the dynamic response of the system is evaluated, using the concepts of SDOF approximation of continuous systems. This enables determination of the envelope of the developed deformations and the tendency for deformation and damage localization throughout the examined building for a given design earthquake scenario. Deformation demands are specified in terms of relative drift ratios referring to the in-plane and the out-of-plane seismic response of the building's structural elements. Drift ratio demands are compared with drift capacities associated with predefined performance limits. The accuracy of the introduced procedure is evaluated through (a) comparison of the response profiles with those obtained from detailed time-history dynamic analysis using a suite of ten strong ground motion records, five of which with near-field characteristics, and (b) evaluation of the performance assessment results with observations reported in reconnaissance reports of the field performance of two neoclassical torsionally-sensitive historical buildings, located in Thessaloniki, Greece, which survived a major earthquake in the past.

• Journal of the Korean Institute of Navigation
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• v.23 no.2
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• pp.29-42
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• 1999

An accurate method of estimating ship maneuverability needs to be developed to evaluate precisely and improve the maneuverability of ships according to the water depth. In order to estimate maneuverability by a mathematical model. The hydrodynamic forces acting on a ship hull and the flow field around the ship in maneuvering motion need to be estimated. The ship speed new the berth is very low and the fluid flow around a ship hull is unsteady. So, the transient fluid motion should be considered to estimate the drag force acting on the ship hull. In the low speed and short time lateral motion, the vorticity is created by the body and grow up in the acceleration stage and the velocity induced by the vorticity affect to the body in deceleration stage. For this kind of problem, CFD is considered as a goof tool to understand the phenomena. In this paper, the 2D CFD code is used for basic consideration of the phenomena to solve the flow in the cross section of the ship considering the ship is slender and the water depth is large enough. The flow fields Added and hydrodynamic forces for the some prescribed motions are computed and compared with the preliminary experiment results. The comparison of the force with measurement is shown a fairly good agreement in tendency. The 3D Potential Calculation based on the Hess & Smith Theory is employed to predict the surge, sway added mass and yaw added moment of inertia of hydrodynamic coefficients for M/V ESSO OSAKA according to the water depth. The results are also compared with experimental data. Finally, the sway added mass of hydrodynamic coefficients for T/S HANNARA is suggested in each water depth.

• Journal of the Korean Geosynthetics Society
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• v.10 no.3
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• pp.53-62
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• 2011

This paper presents the characteristics behavior of dike structure and foundation ground through the shaking table model test. The vibration loadings of design earthquake acceleration of 0.154g was applied to this laboratory model test regarding on dike structure and foundation ground under the structure. The model was formulated with 1/100 design of representative cross section for evaluating the effectiveness of vibration. Based on the test results, we can analysis the behavior of lateral displacement and settlement characteristics of structure under the earthquake loading. The pore water pressure was also monitored in the upper, middle and lower layers of ground. Finally, the actual displacements and pore water pressure of the structure can be predicted by using the results of the laboratory shaking table test.

• Structural Engineering and Mechanics
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• v.76 no.1
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• pp.83-99
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• 2020

Shear walls are structural members in buildings that are used extensively in reinforced concrete frame buildings, and almost exclusively in the UK, regardless of whether or not they are actually required. In recent years, the UK construction industry, led by the Concrete Centre, has questioned the need for such structural elements in low to mid-rise reinforced concrete frame buildings. In this context, a typical modern, 5-storey residential building is studied, and its existing shear walls are replaced with columns as used elsewhere in the building. The aim is to investigate the impact of several design variables, including concrete grade, column size, column shape and slab thickness, on the building's structural performance, considering two punching shear limits (V_Ed/V_Rd,c), lateral drift and accelerations, to evaluate its maximum possible height under wind actions without the inclusion of shear walls. To facilitate this study, a numerical model has been developed using the ETABS software. The results demonstrate that the building examined does not require shear walls in the design and has no lateral displacement or acceleration issues. In fact, with further analysis, it is shown that a similar building could be constructed up to 13 and 16 storeys high for 2 and 2.5 punching shear ratios (V_Ed/V_Rd,c), respectively, with adequate serviceability and strength, without the need for shear walls, albeit with thicker columns.

• International Journal of Railway
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• v.2 no.3
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• pp.118-123
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• 2009

Railway track alignment Standards set a minimum lenght value for straight and circular alignments (art. 5.2.9.), in order to ensure passenger ride comfort in railway vehicles of which dynamic oscillations will thus have to be limited. The transitions between alignments can cause abrupt changes (usually called discontinuities or singular points of the alignment) of curvature, of rate of change of curvature or of rate of change of cant. A passenger is likely to experience effects due to the excitation of the elastic suspension of the vehicle which generates oscillations that are damped as the vehicle moves away from the singularity. The amplitude of these oscillations should be adequately attenuated by the damping of the suspension system within the interval between two successive singular points, especially to avoid resonances. Therefore minimum lengths between two successive singular points are stated in alignment standards. Nevertheless, these nonnative values can be overly conservative in some cases. As an alternative, track alignment designers could try to assess how much the excitation has been attenuated between two successive singular points and thus assess at which point a new singularity may be present without affecting ride comfort. Although such assessment can be made with commercial SW packages which simulate the dynamic behavior of a vehicle considered as a set of rigid bodies interconnected with elastic elements simulating the suspension systems (such as SIMPACK, ADAMS or VAMPIRE), a simplified and user-friendly computation method (based upon the analytical solution of differential equations governing the phenomenon) is made available in this paper to track design engineers, not always used to working with full dynamic models.

• Polymer(Korea)
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• v.29 no.1
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• pp.48-53
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• 2005

Tire wear is one of the factors that most drivers have concerned and is closely related to the tire life. It is very difficult to predict tire wear because the factors affecting tire wear seem to be very comlicated. Tire wear test should be performed at real conditions for the evaluation of tire wear. In this study, we analyze tire wear according to the severities of test courses by using the dedicated test method, more severe than real driving conditions. In order to simplify the factors affecting tire wear, we define roads’ driving severities to be driving severity numbers, DSNs which are obtained by measuring the lateral accelerations of test courses. And we compared tire wear rates and profiles with DSNs. These test results can provide the tire design guide to meet tire wear performance.