• The Journal of the Convergence on Culture Technology
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• v.8 no.5
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• pp.547-552
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• 2022

In this study, shape-based track management by analyzing track irregularity was studied in terms of force-based track irregularity analysis by numerical analysis of wheel-rail interaction force using by the measured vertical irregularity. The effect of the vertical irregularity of the track due to the difference in track types on the wheel-rail interaction force and the track acceleration in the connecting section of the sleeper floating track and the direct fixation track on concrete bed were analyzed. As the results of this study, the measured vertical irregularity was directly affect the vertical wheel load (the wheel-rail interaction force) and the rail acceleration, and it has been demonstrated to change consistently. In this study, the adequacy and necessity of the force-based track irregularity analysis method was verified based on the wheel-rail interaction analysis using the the measured vertical irregularity.

• Geophysics and Geophysical Exploration
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• v.26 no.1
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• pp.1-7
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• 2023

This study derives the expressions of vector gravity and gravity gradient tensor due to an elliptical cylinder. The vector gravity for an arbitrary three-dimensional (3D) body is obtained by differentiating the gravitational potential, including the triple integral, according to the shape of the body in each axis direction. The vector gravity of the 3D body with axial symmetry is integrated along the axial direction and reduced to a double integral. The complex Green's theorem using complex conjugates subsequently converts the double integral into a one-dimensional (1D) closed-line integral. Finally, the vector gravity due to the elliptical cylinder is derived using 1D numerical integration by parameterizing a boundary of the elliptical cross-section as a closed line. Similarly, the gravity gradient tensor due to the elliptical cylinder is second-order differentiated from the gravitational potential, including the triple integral, and integrated along the vertical axis direction reducing it to a double integral. Consequently, all the components of the gravity gradient tensor due to an elliptical cylinder are derived using complex Green's theorem as used in the case of vector gravity.

• Journal of Powder Materials
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• v.29 no.6
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• pp.459-467
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• 2022

Soft magnetic powder materials are used throughout industries such as motors and power converters. When manufacturing Fe-based soft magnetic composites, the size and shape of the soft magnetic powder and the microstructure in the powder are closely related to the magnetic properties. In this study, Fe-Si-Al-P alloy powders were manufactured using various manufacturing process parameter sets, and the process parameters of the vacuum induction melt gas atomization process were set as melt temperature, atomization gas pressure, and gas flow rate. Process variable data that records are converted into 6 types of data for each powder recovery section. Process variable data that recorded minute changes were converted into 6 types of data and used as input variables. As output variables, a total of 6 types were designated by measuring the particle size, flowability, apparent density, and sphericity of the manufactured powders according to the process variable conditions. The sensitivity of the input and output variables was analyzed through the Pearson correlation coefficient, and a total of 6 powder characteristics were analyzed by artificial neural network model. The prediction results were compared with the results through linear regression analysis and response surface methodology, respectively.

• Journal of the Society of Naval Architects of Korea
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• v.60 no.1
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• pp.38-47
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• 2023

According to the government policy of environmental regulations, interest of ship, which made with High-Density Polyethylene (HDPE) as a low-carbon and eco-friendly material, is growing as a substitute for the existing fishery boat hull materials such as FRP, aluminum, steel etc. However, regulations related to the production of HDPE ship are still quite incomplete. Even there are no regulations related to structural analysis. Therefore, in this study, structural analysis is carried out by applying different design loads for each international classification for 38ft class HDPE power boats, and the results are compared and analyzed. According to this study, although there is a correlation between the based pressure value and the analysis result value of each class regulation, it is not necessarily proportional. Also, This analysis result shows a difference not only depending on the size of design load, but also application range of the load, the pressure adjustment factor and section shape. However, the occurrence point and trend of the maximum stress values were quite consistent. It is hoped that the results of this study will be used when establishing HDPE ship structure analysis procedures and standards in the future.

• Design Convergence Study
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• v.17 no.3
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• pp.55-70
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• 2018

This study was conducted as a part of long-term project on the development of a set of design guidelines for a crutch as mobility aids for the handicapped in the lower extremity and the suggestion a practical solution for a crutch design. The purpose of this study is to develop a design of a crutch and a set of prototypes that reflects the characteristics of crutch-gait and has a realistic possibility for mass production-based industry. TOGO, a axillary crutch as the result of this study, shows a number of characteristics distinguished from ordinary crutches. These are (1)Minimize the shock associated with planting of the crutch tips by improving the form and structure of crutch tip and axillary pad, (2)Ergonomically designed crutch in accordance with users' body movement while walking on crutches, (3)Easy length control to maximize mobility and maneuverability by changing the cross section of the crutch revolutionary, (4)Minimize possibilities of safety hazards, and (5)Attractive shape of the crutch to keep user self-esteem. The revolutionary crutch derived from this study results has been patented, and the company is seeking to mass-produce and find ways to commercialize it after reviewing the potential problems that may arise in the mass production environment.

• Journal of Korean Tunnelling and Underground Space Association
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• v.12 no.6
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• pp.451-461
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• 2010

Utilization of the fiber reinforced polymer (FRP) material has been enlarged as a substitution material to the general construction materials having certain long-term problems such as corrosion, etc. However, it could be difficult to apply the FRP material, which has a linear shape generally, to an arch-shaped tunnel structure. Therefore, an attempt has been made in this study to develop a device to form a designed cross section of FRP material by pulling out with a curvature. A sample of the circled FRP product was successfully produced and then the sample has been tested to identify its physical characteristics. Then, intensive feasibility studies on the circled FRP panel to be used for a tunnel lining structure have been carried out by numerical analyses. As a result, it appears that the new circled FRP-concrete composite panel has a high capability to be used for a tunnel lining material without any structural problem.

• Journal of the Korean Society of Industry Convergence
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• v.26 no.5
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• pp.803-812
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• 2023

The subsea separator of an offshore plant for offshore oil and gas development performs the process of separating oil and gas from crude oil produced in the subsea. The oil-gas subsea separator can be divided into a gravity type that separates fluids by gravity and an in-line type that separates fluids using centrifugal force of density. In the case of the deep sea, the development of a small in-line type separator is required due to manufacturing cost and safety problems caused by water pressure. Therefore, in this study, the gas-liquid phase separation efficiency of the subsea separator was identified through the study of the multiphase flow characteristics of the in-line type separator. For the optimal design of the in-line type separator, the shape of the internal swirl element(ISE) was selected first, and the separation efficiency results for each section of the in-line type separator were analyzed. This study was conducted in parallel with experiments and numerical analysis, and it is expected that the reliability and efficiency of the in-line type separator will be improved through the results.

• Journal of Sensor Science and Technology
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• v.32 no.5
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• pp.320-327
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• 2023

In this study, an FPGA-based sealer inspection system was developed to inspect the sealer applied to install vehicle glass on a car body. The sealer is a liquid or paste-like material that promotes adhesion such as sealing and waterproofing for mounting and assembling vehicle parts to a car body. The system installed in the existing vehicle design parts line does not detect the sealer in the glass rotation section and takes a long time to process. This study developed a line laser camera sensor and an FPGA vision signal processing module to solve this problem. The line laser camera sensor was developed such that the resolution and speed of the camera for data acquisition could be modified according to the irradiation angle of the laser. Furthermore, it was developed considering the mountability of the entire system to prevent interference with the sealer ejection machine. In addition, a vision signal processing module was developed using the Zynq-7020 FPGA chip to improve the processing speed of the algorithm that converted the profile to the sealer shape image acquired from a 2D camera and calculated the width and height of the sealer using the converted profile. The performance of the developed sealer application inspection system was verified by establishing an experimental environment identical to that of an actual automobile production line. The experimental results confirmed the performance of the sealer application inspection at a level that satisfied the requirements of automotive field standards.

• Geomechanics and Engineering
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• v.37 no.3
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• pp.293-306
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• 2024

Influenced by the alternating effects of dynamic and static pressure during the mining process of close range coal seams, the surrounding rock support of cross mining roadway is difficult and the deformation mechanism is complex, which has become an important problem affecting the safe and efficient production of coal mines. The paper takes the inclined longwall mining of the 10304 working face of Zhongheng coal mine as the engineering background, analyzes the key strata fracture mechanism of the large inclined right-angle trapezoidal mining field, explores the stress distribution characteristics and transmission law of the surrounding rock of the roadway affected by the mining of the inclined coal seam, and proposes a segmented and hierarchical support method for the cross mining roadway affected by the mining of the close range coal seam group. The research results indicate that based on the derived expressions for shear and tensile fracture of key strata, the ultimate pushing distance and ultimate suspended area of a right angle trapezoidal mining area can be calculated and obtained. Within the cross mining section, along the horizontal direction of the coal wall of the working face, the peak shear stress is located near the middle of the boundary. The cracks on the floor of the cross mining roadway gradually develop in an elliptical funnel shape from the shallow to the deep. The dual coupling support system composed of active anchor rod support and passive U-shaped steel shed support proposed in this article achieves effective control of the stability of cross mining roadways, which achieves effective control of floor by coupling active support and preventive passive support to improve the strength of the surrounding rock itself. The research results are of great significance for guiding the layout, support control, and safe mining of cross mining roadways, and to some extent, can further enrich and improve the relevant theories of roof movement and control.

• Journal of the Korea institute for structural maintenance and inspection
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• v.13 no.3 s.55
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• pp.145-154
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• 2009

Steel-Concrete Composite Deck with I-beam welded is lighter and easier to construct than conventional in situ reinforced concrete slabs due to the I-beam embedded in the corrugated slab. For the calculation of effective flexural rigidity of conventional reinforced concrete structures, methods suggested in Design Standard for Roads and Bridges and ACI have been used. In this paper, the calculation methods were applied to steel-concrete composite deck with I-beam welded and then results of the steel-concrete composite deck were compared with those of reinforced concrete slabs. In addition, applicability of the methods to steel-concrete composite deck with I-beam welded was estimated. In order to compare the effective flexural rigidity, flexural experiments were conducted. Fifteen slabs were built and the variables considered in the experiments were studs, length of the slab, shape of the section and connecting methods.