• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.1
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• pp.426-433
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• 2019

After an earthquake, fire and gas explosions are more likely to cause more casualties in cities with many apartment buildings and large complex buildings. In order to prevent this, seismic design is necessary for the fire protection sprinkler system. However, most systems currently use stainless-steel pipes, although synthetic resin pipes are used in some special places. These materials are susceptible to vibration and earthquakes. This study evaluated the displacement absorption flexibility of polyethylene (PE) and aluminum (Al) multi-layered composite pipes to increase the seismic performance in a vibration environment and during earthquakes. The seismic performance was compared with that of a stainless-steel and PE pipes. The seismic characteristics can be measured by measuring the amount and extent of vibration transmitted by the sprinkler pipe. This method can be used to judge the seismic characteristics to attenuate the vibration during an earthquake. The seismic characteristics of the pipe were verified by comparing the logarithmic attenuation rate to the initial response displacement of the vibration generated by the transverse vibration measurement method.

• Journal of the Korean Society of Industry Convergence
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• v.25 no.4_2
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• pp.587-594
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• 2022

In the 2000s, a lot of cable-type grand bridges are being built in consideration of economic aspects such as the reduction of logistics costs and the distribution of traffic volume due to rapid economic development. In addition, because the recently installed grand bridges are designed in an aesthetic form that matches the surrounding environment as well as the original function of the road bridge, and serves as a milestone in an area and is used as an excellent tourism resource, attracting many vehicles and people, there is an urgent need for a safety structure that can ensure the safety of not only vehicles but also people. In order to make cable-stayed bridge safe on wind for additional five safety structures, main girder models with and without safety structures for wind-tunnel experiments was made, and wind tunnel experiments was carried out to measure aerodynamic force coefficients. Also, wind-resistant analyses of 3D cable-stayed bridge were performed on the basis of wind-tunnel experiment results. From the wind tunnel experiments for the aerodynamic force coefficients of main girder with five safety structures and the wind resistant analyses of cable-stayed bridge without safety structure and with safety structure, it was concluded that the best form of wind-resistant safety was shown in the order of mesh, standard, bracing, hollow, and closed type. And wind-resistant safety of cable-stayed bridge with hollow and closed type on design wind speed 68.0m/sec was not secured. Finally, as five safety structures are installed, maximum rate of stress increments was shown in the order of steel main beam, steel floor beam, concrete floor beam and cables.

• Information Systems Review
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• v.13 no.3
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• pp.15-26
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• 2011

RFID has substituted for a Bar Code to conduct real time data collection and data process in various fields including logistics, electronic, medical treatment, car, textile, steel industry at the business level. Although implementation and use of RFID has been facilitated constantly, the majority of businesses hesitate to implement RFID system. Hence in this study, we conducted a performance evaluation through quantitative/qualitative analysis on case studies in various industries. This study results could be utilized as basic data for RFID system diffusion, and it will primarily contribute to spread of RFID system implementation.

• Steel and Composite Structures
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• v.23 no.2
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• pp.161-172
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• 2017

A new composite tube connection method called the pre-tightened teeth connection technique is proposed to improve the composite tube connection efficiency. This paper first introduces the manufacturing process of the proposed technique. It then outlines how the mechanical properties of this technology were tested using four test groups. The factors that influence the load-bearing capacity and damage model of the connection were analyzed, and finally, the transfer load mechanism was investigated. The following conclusions can be obtained from the research results. (1) The new technique improves the compressive connection efficiency by a maximum of 79%, with the efficiency exceeding that of adhesive connections of the same thickness. (2) Changing the depth of teeth results in two types of damage: local compressive damage and shear damage. The bearing capacity can be improved by increasing the depth, length, and number of teeth as well as the pre-tightening force. (3) The capacity of the technique to transfer high loads is a result of both the relatively high interlaminar shear strength of the pultruded composite and the interlaminar shear strength increase provided by the pre-tightening force. The proposed technique shows favorable mechanical properties, and therefore, it can be extensively applied in the engineering field.

• The Journal of Industrial Distribution & Business
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• v.9 no.8
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• pp.27-34
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• 2018

Purpose - This paper discussed and illustrated the most efficient method to calculate the distribution centers for a national project in China. Through demonstration of implementing the GIS, spatial analysis, and location calculation model, this paper mainly dealt with the construction distribution problem and inconvenient supply of materials problems. Research design, data, and methodology - In this paper, the research design structure based on three steps: implementing the Geographic Information System to locate the points coordination data, calculating the distribution centers of the project, and optimizing the most efficient and effective coordination. The data of the calculation is from an actual project. The methodology of this paper is summarizing the spatial analysis capabilities and digital graphic data calculation to locate logistics distribution centers, and since the illustration of the calculation is useful for locating the coordination, the result of this paper has certain reference values for the project construction. Results - This paper illustrates the steel and cement resource of every distribution point to confirm the most efficient distribution center location coordination. Conclusions - The integrated logistical management models are used to ensure the results for the purposes of our calculation. The result of the calculation is also a useful example for future Chinese national projects.

• Structural Engineering and Mechanics
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• v.71 no.3
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• pp.283-290
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• 2019

In global competition manufacturing companies have to produce modern, new constructions from advanced materials in order to increase competitiveness. The aim of my research was to develop a new composite cellular plate structure, which can be primarily used for structural elements of road, rail, water and air transport vehicles (e.g. vehicle bodies, ship floors). The new structure is novel and innovative, because all materials of the components of the newly developed structure are composites (laminated Carbon Fiber Reinforced Plastic (CFRP) deck plates with pultruded Glass Fiber Reinforced Plastic (GFRP) stiffeners), furthermore combines the characteristics of sandwich and cellular plate structures. The material of the structure is much more advantageous than traditional steel materials, due mainly to its low density, resulting in weight savings, causing lower fuel consumption and less environmental damage. In the study the optimal construction of a given geometry of a structural element of a road truck trailer body was defined by single- and multi-objective optimization (minimal cost and weight). During the single-objective optimization the Flexible Tolerance Optimization method, while during the multi-objective optimization the Particle Swarm Optimization method were used. Seven design constraints were considered: maximum deflection of the structure, buckling of the composite plates, buckling of the stiffeners, stress in the composite plates, stress in the stiffeners, eigenfrequency of the structure, size constraint for design variables. It was confirmed that the developed structure can be used principally as structural elements of transport vehicles and unit load devices (containers) and can be applied also in building construction.

• Steel and Composite Structures
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• v.48 no.2
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• pp.191-206
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• 2023

The present research investigates how micromechanical models affect the behavior of Functionally Graded (FG) plates under different boundary conditions. The study employs diverse micromechanical models to assess the effective material properties of a two-phase particle composite featuring a volume fraction of particles that continuously varies throughout the thickness of the plate. Specifically, the research examines the vibrational response of the plate on a Winkler-Pasternak elastic foundation, considering different boundary conditions. To achieve this, the governing differential equations and boundary conditions are derived using Hamilton's principle, which is based on a four-variable shear deformation refined plate theory. Additionally, the Galerkin method is utilized to compute the plate's natural frequencies. The study explores how the plate's natural frequencies are influenced by various micromechanical models, such as Voigt, Reuss, Hashin-Shtrikman bounds, and Tamura, as well as factors such as boundary conditions, elastic foundation parameters, length-to-thickness ratio, and aspect ratio. The research results can provide valuable insights for future analyses of FG plates with different boundaries, utilizing different micromechanical models.

• Smart Structures and Systems
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• v.3 no.3
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• pp.281-298
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• 2007

The load carrying capacity of a bridge needs to be properly assessed to operate the bridge safely and maintain it efficiently. For the evaluation of load carrying capacity considering the current state of a bridge, static and quasi-static loading tests with weight-controlled heavy trucks have been conventionally utilized. In these tests, the deflection (or strain) of the structural members loaded by the controlled vehicles are measured and analyzed. Using the measured data, deflection (or strain) correction factor and impact correction factor are calculated. These correction factors are used in the enhancement of the load carrying capacity of a bridge, reflecting the real state of a bridge. However, full or partial control of the traffic during the tests and difficulties during the installment of displacement transducers or strain gauges may cause not only inconvenience to the traffic but also the increase of the logistics cost and time. To overcome these difficulties, an alternative method is proposed using an excited response part of full measured ambient acceleration data by ordinary traffic on a bridge without traffic control. Based on the modal properties extracted from the ambient vibration data, the initial finite element (FE) model of a bridge can be updated to represent the current real state of a bridge. Using the updated FE model, the deflection of a bridge akin to the real value can be easily obtained without measuring the real deflection. Impact factors are obtained from pseudo-deflection, which is obtained by double-integration of the acceleration data with removal of the linear components on the acceleration data. For validation, a series of tests were carried out on a steel plategirder bridge of an expressway in Korea in four different seasons, and the evaluated load carrying capacities of the bridge by the proposed method are compared with the result obtained by the conventional load test method.

• Journal of Navigation and Port Research
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• v.45 no.6
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• pp.346-351
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• 2021

With the goal of eradicating overwork, overload, and speeding of general freight cars(cargo) by the Ministry of Land, Infrastructure and Transport, Infrastructure and Transport, the "The Fare of safe transportation for freight cars System" has been enforced since 2020. 'The Fare of safe transportation for freight cars' rate for each item is being applied and supplemented, but the 'The Cost of safe transportation for freight cars' of general freight cars (cargo) and steel items is under discussion. The purpose of this study was to estimate the willingness to pay( WTP) for cargo. A survey was conducted on shippers, transportation companies (arrangers, carriers), and cargo drivers (using direct questioning among contingent valuation method (CVM) and the Tobit Regression analysis was conducted, and the average and median values of freight rates were derived using the estimated results, and the willingness to pay by tonnage of freight cars was confirmed. It is expected that the results of this study can be used as a reference to the "The Fare of safe transportation for freight cars Committee" an organization for deliberation and resolution of the 'The Cost of safe transportation for freight cars'.

• Korean Journal of Construction Engineering and Management
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• v.9 no.1
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• pp.176-186
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• 2008

The radio frequency identification (RFID) technology allows various forms of applications in many industries including construction. and in Korea, RFID has already been adopted for the use in daily labor control, logistics monitoring of ready-mix concrete, supply chain management of long-lead items, such as structural steel members and curtain walls. Even though RFID tags have varied reading performances depending on various factors including material of tracking target and surrounding environment, there is no information on how much the reading performance of an RFID tag can be achieved against a specific construction components or materials. Therefore, the objective of this research is to identify the actual reading performance of various RFID technologies and to derive a method to maximize the reading performance for the use in the supply chain management process of curtain wall components.