• Journal of the Society of Naval Architects of Korea
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• v.60 no.4
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• pp.278-287
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• 2023

This study aims to analyze and evaluate the structural strength of a 53ft Liquefied Natural Gas (LNG) tank container according to International Organization for Standardization (ISO) 1496-3, amidst growing global demand for LNG transportation. The research was conducted in two main stages: structural analysis using Finite Element Analysis (FEA) under various load conditions, and structural strength tests following ISO 1496-3 test procedures. The structural analysis was performed considering different loading conditions to assess the structural safety of the tank container. Calculated stresses were compared with allowable stress under specified load conditions. The structural strength tests were conducted at Mokpo National University's Subsea Umbilical cable Riser Flowline R&D Center, which provided a suitable testing environment. The study found that calculated stresses met the allowable stress under specified load conditions, confirming the structural safety of the tank container. Additionally, the maximum deformation and permanent deformation satisfied the design criteria for all test cases, indicating the container's structural strength meets requirements. The research also contributed valuable data for future structural strength tests of similar products and facilitated the development of safe and efficient LNG transportation solutions by developing effective test procedures in accordance with ISO 1496-3 standards.

• Korean Journal of Agricultural Science
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• v.49 no.2
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• pp.269-284
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• 2022

The development of radish collectors has the potential to increase radish yields while decreasing the time and dependence on human labor in a variety of field activities. Stress and fatigue analyses are essential to ensure the optimal design and machine life of any agricultural machinery. The objectives of this research were to analyze the stress and fatigue of major components of a tractor-mounted radish collector under dynamic load conditions in an effort to increase the design dependability and dimensions of the materials. An experiment was conducted to measure the shaft torque of stem-cutting and transferring conveyor motors using rotary torque sensors at different tractor ground speeds with and without a load. The Smith-Watson-Topper mean stress equation and the rain-flow counting technique were utilized to determine the required shear stress with the distribution of the fatigue life cycle. The severity of the operation was assessed using Miner's theory. All running conditions produced more than 10⁷ of high cycle fatigue strength. Furthermore, the highest severity levels for motor shafts used for stem cutting and transferring and for transportation joints and cutting blades were 2.20, 4.24, 2.07, and 1.07, and 1.97, 3.81, 1.73, and 1.07, respectively, with and without a load condition, except for 5.24 for a winch motor shaft under a load. The stress and fatigue analysis presented in this study can aid in the selection of the most appropriate design parameters and material sizes for the successful construction of a tractor-mounted radish collector, which is currently under development.

• Journal of Electrical Engineering and Technology
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• v.10 no.3
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• pp.1370-1376
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• 2015

Generally, an autotransformer(AT) feeding system consists of double tracks, up and down, with the trolley wire and feeder wire of the up and down tracks connected in the sectioning post(SP). Consequently, load current or fault current flows on two tracks based on catenary impedance characteristics, making it difficult to estimate catenary impedance accurately. This paper presents a technique for the estimation of catenary impedance using boosting current compensation based on the current division characteristics of an AT feeding system to improve the operation performance of impedance relay. To verify the technique, we model an AT feeding system through a power analysis program (PSCAD/EMTDC) and simulate various operation and fault conditions. Through the simulation, we confirmed that the proposed technique has estimated catenary impedance with a similar degree of accuracy to the actual catenary impedance

• Structural Engineering and Mechanics
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• v.48 no.3
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• pp.395-414
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• 2013

The present study fundamentally investigated the mechanical performance of the rib-stiffened super-wide bridge deck with twin box girders in concrete, which is a very popular application to efficiently widen the bridges with normal span. The shear lag effects of the specific cross-sections were firstly studied. The spatial stress distribution and local stiffness of the bridge deck with twin box girders were then investigated under several typical wheel load conditions. Meanwhile, a comparative study for the bridge deck with and without stiffening ribs was also carried out during the investigation; thereby, a design optimization for the stiffening ribs was further suggested. Finally, aiming at the preliminary design, an approximate methodology to manually calculate the bending moments of the rib-stiffened bridge deck was analytically proposed for engineers to quickly assess its performance. This rib-stiffened bridge deck with twin box girders can be widely applied for concrete (especially concrete cable-stayed) bridges with normal span, however, requiring a super-wide bridge width due to the traffic flow.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.10a
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• pp.1335-1338
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• 2004

This paper describes the result of structure analysis of body structure. The purpose of the analysis is to evaluate an safety which body structure shall be considered fully sufficient rigidity so as to satisfy proper system function under maximum load and operating condition. Material of body structure applied an aluminum alloy. Body structure consist of side frame, under frame, roof frame, end frame. FEM analysis is based on 'Performance Test Standard for Electrical Multiple Unit, noticed by Ministry of Construction & Transportation, in 2000 ' and reference code is JIS E 7105. The analysis results have been very safety and stable for design load conditions.

• Earthquakes and Structures
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• v.22 no.4
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• pp.431-437
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• 2022

One of the best choice for transportation of oil and gas at the end of rivers or seas is concrete pipelines. In this article, a concrete pipe at the end of river is assumed under the earthquake load. The Classic shell theory is applied for the modelling and the corresponding motion equations are derived by energy method. An external force induced by fluid around the pipe is asssumed in the final motion equations. For the solution of motion equations, the differential quadrature method (DQM) and Newmark method are applied for deriving the dynamic deflection of the pipe. The effects of various parameters including boundary conditions, fluid and length to thickness ratio are presented on the seismic response of the concrete pipe. The outcomes show that the clamped pipe has lower dynamic deflection with respect to simply pipe. In addition, with the effect of fluid, the dynamic defelction is increased significantly.

• Earthquakes and Structures
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• v.22 no.5
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• pp.439-445
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• 2022

One of the best choice for transportation of oil and gas at the end of rivers or seas is concrete pipelines. In this article, a concrete pipe at the end of river is assumed under the earthquake load. The Classic shell theory is applied for the modelling and the corresponding motion equations are derived by energy method. An external force induced by fluid around the pipe is asssumed in the final motion equations. For the solution of motion equations, the differential quadrature method (DQM) and Newmark method are applied for deriving the dynamic deflection of the pipe. The effects of various parameters including boundary conditions, fluid and length to thickness ratio are presented on the seismic response of the concrete pipe. The outcomes show that the clamped pipe has lower dynamic deflection with respect to simply pipe. In addition, with the effect of fluid, the dynamic defelction is increased significantly.

• Journal of Korean Society of Transportation
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• v.34 no.3
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• pp.263-277
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• 2016

Traffic safety in freeway work zones is of keen interest since both crash frequency and severity are much higher than those in general freeway sections. The lane closure in work zones results in greater work load of drivers due to compulsory lane changes and speed reduction. Therefore, traffic merging control is an effective countermeasure for enhancing work zone safety. This study proposed an integrated framework based on driving and traffic simulations to evaluate traffic merging control methods in terms of traffic safety. In addition to the conventional merging method using the taper, joint merge and chicane-type merge were evaluated by the proposed methodology. Chicane-type merge outperformed other methods under level of service (LOS) A and B. On the other hand, it was identified that joint merge showed the best safety performance under LOS C traffic conditions.

• Steel and Composite Structures
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• v.25 no.1
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• pp.117-126
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• 2017

The component method is an analytical approach for investigating the moment-rotation relationship of steel connections. In this study, the component method was improved from two aspects: (i) load analysis of mechanical model; and (ii) combination of spring elements. An optimized component method with more reasonable component models, spring arrangement position, and boundary conditions was developed using finite element analysis. An experimental testing program in two major-axis and two minor-axis connections under symmetrically loading was carried out to verify this method. The initial rotational stiffness obtained from the optimized component method was consistent with the experimental results. It can be concluded that (i) The coupling stiffness between column and beam flanges significantly affects the effective height of the tensile-column web. (ii) The mechanical properties of the bending components were obtained using an equivalent t-stub model considering the bending capacity of bolts. (iii) Using the optimized mechanical components, the initial rotational stiffness was accurately calculated using the spring system. (iv) The characteristics of moment-rotation relationship for beam to column connections were effectively expressed by the SPRING element analysis model using ABAQUS. The calculations are simpler, and the results are accurate.

• Structural Engineering and Mechanics
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• v.52 no.5
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• pp.1019-1032
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• 2014

Rails are key elements in railway superstructure since these elements receive directly the train load transmitted by the wheels. Simultaneously, rails must provide effective stress transference to the rest of the track elements. This track element often deteriorates as a consequence of the vehicle passing or manufacturing imperfections that cause in rail several defects. Among these rail defects, transverse cracks highlights and are considered a severe pathology because they can suddenly trigger the rail failure. This study is focused on UIC-60 rails with transverse cracks. A 3-D FEM model is developed in ANSYS for the flawless rail in which conditions simulating the crack presence are implemented. To account for the inertia loss of the rail as a consequence of the cracking, a reduction of the bending stiffness of the rail is considered. The numerical models have been calibrated using the first four bending vibration modes in terms of frequencies. These vibration frequencies have been obtained using the Experimental Modal Analysis technique, studying the changes in the modal parameters of the rails induced by the crack and comparing the results obtained by the model with experimental results. Finally, the calibrated and validated models for the single rail have been implemented in a complete railway ballasted track FEM model in order to study the static influence of the cracks on the rail deflection caused by a load passing.