• Transactions of the Korean Society of Automotive Engineers
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• v.15 no.5
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• pp.125-132
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• 2007

In order to provide consumers with safety informations of vehicles according to the Korean New Car Assessment Program(KNCAP), the evaluation results and the star ratings of 21 vehicles for the side impact tests have been reported since 2003. Now, the KNCAP considers changing the side impact dummy from EuroSID-1 to EuroSID-2 near future. The rib deflection of EuroSID-2 is 20-30% higher than that of EuroSID-1 because of the removal of "Flat Tops" effect. In this study, the effect of changing the side impact dummy from EuroSID-1 to EuroSID-2 in the KNCAP side impact evaluation is estimated through the previous KNCAP evaluation results. The results show that the decrease of the star ratings would be one star($\bigstar$) approximately.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.829-835
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• 2011

This paper aims for proposed the deflection limit on vibration serviceability of high-speed railway bridges considering passenger's comfort when a train passes a railway bridge. The vertical acceleration signals of passenger cars obtained from test were compared with them from the bridge-train transfer function by riding KTX. The deflections by KTX of seven high speed railway bridges were assumed as sine and haversine wave. The deflection limit on vibration serviceability of high-speed railway bridges considering passenger's comfort when a train passes a railway bridge duration can be expanded using bridge-train transfer function and bridge comfort limit considering serviceability due to bridge vibration. And it was compared to other allowable deflection limits of railway bridge design specifications.

• Smart Structures and Systems
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• v.19 no.4
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• pp.431-439
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• 2017

This investigation is aimed to develop a model of experimental-computation determination of a support moment of a cantilever beam loaded with concentrated force at its end including the optimal choice of coordinates of deflection data points and parameters of transformation of deflection data in case of insufficient accuracy of the assignment of initial parameters (support settlement, angle of rotation of the bearing section) and cantilever beam length. The influence of distribution and characteristics of sensors on the cantilever beam on the accuracy of determining the support moment which improves in the course of transition from the uniform distribution of sensors to optimal non-uniform distribution is shown. On the basis of the theory of inverse problems the method of transformation reduction at numerical differentiation of deflection functions has been studied. For engineering evaluation formulae of uncertainty estimate to determine a support moment of a cantilever beam at predetermined uncertainty of measurements using sensors have been obtained.

• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1254-1258
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• 2007

Electro-active polymer (EAP), one of the smart materials, is a new alternative offering ultra-precise movements and bio-compatibility. We present the results of the design, fabrication, and performance evaluation of a fabricated diaphragm-type polymer actuator using segmented polyurethane(SPU). This paper illustrates the relationship between the elastic modulus and maximum deflection as a key property of the Maxwell stress effect and also presents the relationship between the dielectric constant and maximum deflection as a key property of the electrostriction effect, especially in polymer actuators using SPU. A diaphragm-type actuator was used to induce an equation of the vertically distributed load by using a fully clamped circular plate as the boundary condition. To verify the equation, the results were compared to the data measured from load cell. In the near future, a low-cost check valves and bio-robot can be applied by its actuators.

• Transactions of the Korean Society of Automotive Engineers
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• v.11 no.3
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• pp.124-130
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• 2003

Many structural evaluation procedures of road and airfield pavements use the Falling Weight Deflectometer (FWD) as a critical element of non-destructive deflection testing. FWD is a trailer mounted device that provides accurate data on pavement response to dynamic wheel loads. A dynamic load is generated by dropping a mass from a variable height onto a loading plate. The magnitude of the load and the pavement deflection are measured by a load celt and geophones. And database concerning pavement damage should be enhanced to analyze loss of thickness asphalt layer caused from the plastic deformation of pavement structure, such as cracking or rutting. The prototype FWD is developed, which consists of chassis system, hydraulic loading system, data acquisition and analysis system. This system subsequently merged to from automation management system and is then validated and updated to produce a working FWD which can actually be used in the field.

• Journal of the Korea Safety Management & Science
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• v.23 no.4
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• pp.67-72
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• 2021

To ensure the safety and functionality of a railroad bridge, maintaining the integrity of the bridge via continuous structural health monitoring is important. However, most structural integrity monitoring methods proposed to date are based on modal responses which require the extracting process and have limited availability. In this paper, the applicability of the existing damage identification method based on free-vibration reponses to time-domain deflection shapes due to moving train load is investigated. Since the proposed method directly utilizes the time-domain responses of the structure due to the moving vehicles, the extracting process for modal responses can be avoided, and the applicability of structural health evaluation can be enhanced. The feasibility of the presented method is verified via a numerical example of a simple plate girder bridge.

• International Journal of Highway Engineering
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• v.15 no.1
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• pp.95-102
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• 2013

PURPOSES: The existing method evaluating the existence of the hollows in concrete pavement does not consider the stiffness of pavement. In addition, the method uses unreasonable logic judging the hollow existence by the deflection caused by zero loading. In this study, the deflection of slab corner due to heavy weight deflectometer (HWD) was measured in concrete pavement sections where underground structures are located causing the hollows around them. METHODS: The modulus of subgrade reaction obtained by comparing the actual deflection of slab to the result of finite element analysis was calibrated into the composite modulus of subgrade reaction. The radius of relative stiffness was calculated, and the relationship between the ratio of HWD load to the radius of relative stiffness and the slab deflection was expressed as the curve of secondary degree. RESULTS: The trends of the model coefficients showing width and maximum value of the curve of secondary degree were analyzed by categorizing the pavement sections into three groups : hollows exist, additional investigation is necessary, and hollows do not exist. CONCLUSIONS: The results analyzed by the method developed in this study was compared to the results analyzed by existing method. The model developed in this study will be verified by analyzing the data obtained in other sections with different pavement structure and materials.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.35 no.1
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• pp.229-236
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• 2015

In this study, the resilient modulus test and Light Weight Deflectormeter (LWD) test were conducted to simulate the moving vehicle load for the evaluation of the internal failure of epoxy asphalt pavement. The Measured displacement in the resilient modulus test of epoxy asphalt concrete showed very little residual deformation under repeated loads unlike the conventional asphalt. Therefore, the test results were evaluated as a normal state due to its similarity with elastic deformation. The deflection results from the resilient modulus tests were converted to the surface deflection modulus and the normal range of surface deflection modulus was estimated applying LWD measurement of 1 SIGMA level. Internal failure of pavements were estimated using the suspicious failure range at $60^{\circ}C$ and hysteresis. Internal moisture penetration and a decrease in bonding were observed in partial areas at $140{\mu}m$ of surface deflection. However, the areas showed inflection points in the hysteresis. Field investigation by suggested criterion indicated a high degree of accuracy.

• Journal of the Korea institute for structural maintenance and inspection
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• v.14 no.2
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• pp.184-192
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• 2010

The member deflection is one of the most important considerations for the serviceability evaluation of reinforced concrete (RC) structures, and the concept of the effective moment of inertia has been generally used for its estimation. However, the actual service load applied on an existing RC beam may not be easily obtained, for which the estimation of beam deflection by existing methods can be difficult to obtain. Therefore, based on the correlation between cracks and deflection in a RC beam, this study proposed a method to estimate the deflection of RC beams directly from the condition of cracks not using the actual loads acting on the member as its input data. The proposed method extensively utilized the relationships among sums of crack widths, average strains, and curvatures, and modification factors obtained from regression analysis were also introduced to improve its accuracy. The deflections of members were successfully estimated by the proposed method independent from applied loads, which was also easy to apply compared to the existing methods based on the effective moment of inertia.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• v.y2005m4
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• pp.99-105
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• 2005

To evaluate structural safety factor of the jet vane for the thrust deflection system under the dynamic pressure and very high temperature($2700^{\circ}C$) of the combustion gas flow, the high temperature tension tests of refractory metals and 3-D nonlinear numerical simulations are performed. Through the analysis of high temperature structural behavior for jet vane, the structural safety of jet vane is evaluated, and numerical results are compared with static pound tests of jet vanes. It has been found that most of structural and thermal loading is concentrated on the vane shaft which worked as safe under $1400^{\circ}C$. From the comparison of static ground tests and numerical results, the evaluation criterion using the vane load and shaft displacement is more useful to estimate the structural safety than using the equivalent stress.