• Journal of the Society of Disaster Information
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• v.7 no.3
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• pp.190-197
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• 2011

In this paper, an analytical and experimental study is performed in order to determine the effects of interaction between a vehicle and a structure. For this purpose, a wheel tracking machine and an adequate single span bridge are designed. Results presented in the paper show that the real vehicle tracking accelerations including the interaction between the vehicle and the structure produce additional effects on the dynamic behavior of the structure including reversal and contrary behavior. Also, the interaction between the vehicle and the bridge is reproduced by applying the identified real vehicle tracking accelerations to a general finite element analysis program.

• Journal of the Korean Society of Safety
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• v.27 no.6
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• pp.93-98
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• 2012

In order to capture the fast crack propagation in an unmanipulated concrete fracture test, we employed mechanoluminascent(ML) material, which emits visible light when stressed, as a crack visualization tool. Three-point bending fracture test setup, a paint type ML material and a high speed camera were used to capture the images of fast moving cracks. The maximum size of coarse aggregates of concrete was used as an experimental parameter. The crack images, loading, and crack mouth opening displacement were successfully recorded as a function of time elapsed. From the test results, several interesting cracking behavior in the unmanipulated fracture test was observed in such that (1) the crack moves fast while the load is slowly decreased after the maximum loading, and (2) the crack in concrete with larger coarse aggregates moves faster than the others.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.6
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• pp.474-483
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• 2003

In this study, the dynamic characteristics of a catenary system and pantograph supplying electrical power to high-speed trains are investigated. One of the most important issues accompanied by increasing the speed of high-speed rail is stabilization of current collection. To stabilize current collection, it is necessary the contact force between the catenary and the pantograph to be kept continuous without loss of contact. The analytical model of a catenary and a pantograph is constructed to simulate the behavior of an actual system. The analysis of the catenary based on the Finite Element Method (FEM) is performed to develop a catenary model suitable for high speed operation. The reliability of the models is verified by the comparison of the excitation test with Fast Fourier Transform (FFT) data of the actual system. The static deflection of the catenary, stiffness variation in contact lines, dynamic response of the catenary undergoing constant moving load, contact force, and each state of the pantograph model were calculated. It is confirmed that a catenary and pantograph model are necessary for studying the dynamic behavior of the pantograph system.

• Journal of the Korea Society of Computer and Information
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• v.23 no.9
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• pp.51-56
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• 2018

Currently, many households raise their companion animals for personal reasons. In this environment, the companion animal is left alone in the home, the owner of the companion animal is increasingly curious about the behavior pattern of the companion animal left alone, and there are many devices that can solve this question. In this paper, we have designed and implemented a Bluetooth-based slave device (beacon in this paper) and a router capable of connecting to a broadband network that can observe behavior patterns of companion animals by using advanced ICT technology. The Bluetooth router designed and implemented in this paper installs a beacon in the home, receives the beacon signal from the device and the beacon installed by the companion animal, and transmits the moving line of the companion animal to the owner of the companion animal through the broadband network, so that it can be confirmed in real time through the app for the provided smart phone.

• Journal of the Architectural Institute of Korea Planning & Design
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• v.35 no.12
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• pp.21-29
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• 2019

The purpose of the study is to be the pedestrian integrated circulation system of malling route and the third route in Mixed-use Building based on User Behavior. The study has performed by the following approaches: Initially, literature reviews are performed related to a pedestrian route by user in mixed-use building. Second, general and stroller users moving route are analyzed based on the outcome of the case study. Finally, the study develops the efficient pedestrian integrated circulation system of malling route and the third route in Mixed-use Building. According to the study, the following conclusions were made: First, An integrated plan for escalators and EVs, which are accessible to both users and strollers, is needed. Second, The entrance automatic door and circulation elements should be connected for continuous move by the stroller users. Finally, The circulation system of complex buildings should be a simple spatial structure and route plan that users can easily recognize.

• Journal of Surface Science and Engineering
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• v.54 no.4
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• pp.200-208
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• 2021

This paper investigated generation behavior of micro-arcs and growth behavior of PEO films on the AA7050 disc specimen in 0.1 M NaAlO₂ solution under the application of 1200 Hz anodic pulse current. Morphologies, thickness and surface roughness of PEO films were examined at the edge part and central part separately. Micro-arcs were generated first at the edge part and then moved towards the central part with PEO treatment time, indicating lateral growth of PEO films. The lateral growth resulted in uniform PEO thickness of about 5 ㎛ and surface roughness of about 0.5 ㎛. Moving of the arcs from the edge towards the central part appeared only one time and large size arcs were generated at the edge before completing the central part with small size micro-arcs. This suggests that vertical growth starts before completing the lateral growth. Large size arcs generated at the edge resulted in the formation of relatively large size pores within the PEO films on the AA7050 disc specimen.

• Health Policy and Management
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• v.32 no.1
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• pp.29-44
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• 2022

Background: This study was conducted to analyze the impact of having a usual source of care on health behaviors of the middle aged and the elderly, in order to investigate the potential effect of enhancing primary health care in a Korean context. Methods: This study constructed a balanced panel of middle-aged and elderly samples using the Korea Health Panel 2016-2018, and fixed-effect models were used to analyze the data. Results: Among three sets of dependent variables (physical activity, smoking, drinking), statistically significant results were found only in physical activity. Subgroup analysis showed that this effect was not observed in the late elderly (aged 75 and older) and those without chronic diseases. Conclusion: Results of the study implied that enhancing primary health care among middle age and the elderly may have an effect on improving health behaviors. Moving forward to person-centered primary health care from disease-focused primary health care should be considered in high-risk groups such as the middle aged and the elderly with chronic diseases.

• Geomechanics and Engineering
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• v.28 no.1
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• pp.89-105
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• 2022

The behavior of the soil subgrade is complex and irregular against loads. When modeling, the soil is often replaced by a more straightforward system called a subgrade model. The Winkler method of linear elastic springs is a popular method of soil modeling in which the spring constant shows the modulus of subgrade reaction. In this research, the factors affecting the distribution of the modulus of subgrade reaction of elastoplastic subgrades are examined. For this purpose, critical theories about the modulus of subgrade reaction were examined. A square raft foundation on a sandy soil subgrade with was analyzed at different internal friction angles and Young's modulus values using ABAQUS software. To accurately model the actual soil behavior, the elastic, perfectly plastic constitutive model was applied to investigate a foundation on discrete springs. In order to increase the accuracy of soil modeling, equations have been proposed for the distribution of the subgrade reaction modulus. The constitutive model of the springs is elastic, perfectly plastic. It was observed that the modulus of subgrade reaction under an elastic load decreased when moving from the corner to the center of the foundation. For the ultimate load, the modulus of subgrade reaction increased as it moved from the corner to the center of the foundation.

• Structural Engineering and Mechanics
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• v.90 no.1
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• pp.97-106
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• 2024

This paper presents a significant contribution to aided design by conducting an analytical examination of geometric links with the aim of establishing criteria for assessing an analogy measure of the extrinsic geometric and kinematic characteristics of the Variable Compression Ratio (VCR) engine with a Geared Mechanism (GBCM) in comparison to the existing Fixed Compression Ratio (FCR) engine with a Standard-Reciprocating Crankshaft configuration. Employing a mechanical approach grounded in projective computational methods, a parametric study has been conducted to analyze the kinematic behavior and geometric transformations of the moving links. The findings indicate that in order to ensure equivalent extrinsic behavior and maintain consistent input-output performance between both engine types, precise adjustments of intrinsic geometric parameters are necessary. Specifically, for a VCR configuration compared to an FCR configuration, regardless of compression ratio and gearwheel radius, for the same crankshaft ratios and stroke lengths, it is imperative to halve lengths of connecting rods, and crank radius. These insights underscore the importance of meticulous parameter adjustment in achieving comparable performance across different engine configurations, offering valuable implications for design optimization.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.6
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• pp.1655-1665
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• 2014

Dynamic displacements of structures shows general behavior of structures. Generally, It is used to estimate structure condition and trustworthy physical quantity directly. Especially, measuring vertical displacement which is affected by moving load is very important part to find or identify a problem of bridge in advance. However directly measuring vertical displacement of the bridge is difficult because of test conditions and restriction of measuring equipment. In this study, Artificial Neural Network (ANN) is used to suggest estimation method of bridge displacement to overcome constrain conditions, restriction and so on. Horizontal strain and vertical displacement which are measured by appling random moving load on the bridge are applied for learning and verification of ANN. Measured horizontal strain is used to learn ANN to estimate vertical displacement of the bridge. Numerical analysis is used to acquire learning data for axis strain and vertical displacement for applying ANN. Moving load scenario which is made by vehicle type and vehicle distance time using Pearson Type III distribution is applied to analysis modeling to reflect real traffic situation. Estimated vertical displacement in respect of horizontal strain according to learning result using ANN is compared with vertical displacement of experiment and it presents vertical displacement of experiment well.