• Steel and Composite Structures
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• v.50 no.6
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• pp.689-703
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• 2024

Construction of high-rise structures, formwork systems that can be installed quickly, resistant to external loads, can be used more than once, have become a necessity. Timber and composite timber materials are preferred in the formation of such formwork systems due to their durability, ease of assembly, light weight and easy to use more than one time. Formwork beams are the most commonly used structural component in the formation of such formwork systems, and these beams can be damaged for different reasons during their lifetime. In this study, H20 top P type timber formwork beams with 1800 and 2450 mm length which is among the products of DOKA(c) company is damaged under the effect of static loading up to a high load level of 85% of the maximum ultimate capacity and after being retrofitted using anchored CFRP strips, performance and behavior of the beams under the influence of various loading types such as static, fatigue and impact are investigated experimentally. Two different lengths of retrofitted timber formwork beams were tested by applying monotonic static, fatigue and impact loading and comments were made about the effects of the retrofit method on performance under different loading types.

• Nuclear Engineering and Technology
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• v.55 no.12
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• pp.4477-4490
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• 2023

Fuel locking mechanisms (FLMs) are essential in upward-flow research reactors to prevent accidental fuel separation from the core during reactor operation. This study presents a novel design concept for a remotely controlled plate-type nuclear fuel locking mechanism. By employing electromagnetic field analysis, we optimized the design of the electromagnet for fuel unlocking, allowing the FLM to adapt to various research reactor core designs, minimizing installation space, and reducing maintenance efforts. Computational flow analysis quantified the drag acting on the fuel assembly caused by coolant upflow. Subsequently, we performed finite element analysis and evaluated the structural integrity of the FLM based on the ASME boiler and pressure vessel (B&PV) code, considering design loads such as dead weight and flow drag. Our findings confirm that the new FLM design provides sufficient margins to withstand the specified loads. We fabricated a prototype comprising the driving part, a simplified moving part, and a dummy fuel assembly. Through basic operational tests on the assembled components, we verified that the manufactured products meet the performance requirements. This remote-controlled micro locking mechanism holds promise in enhancing the safety and efficiency of plate-type nuclear fuel operation in upflow research reactors.

• Design & Manufacturing
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• v.18 no.2
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• pp.23-28
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• 2024

The automobile industry is a wide range of related industries, including parts manufacturing and vehicle assembly, press processing is an essential element in making automobiles. Press processing is a processing method for metal sheets that has relatively high dimensional and shape precision and is suitable for mass production. It refers to processing by attaching a special tool, a mold, to a press machine. Recently, the automobile industry is attempting to reduce the weight of automobiles in order to reduce carbon emissions due to global warming, and the use of high-strength steel sheets, which are lighter than general structural steel sheets, is a natural trend. Shear processing is required to use high-strength steel, and the shape of the shear surface created by shear processing has a significant impact on the quality of the automobile. Therefore, various methods are being attempted to improve the share surface during shear processing. Among them, shaving processing is a method of shearing the primary shearing area again, and it is difficult to obtain an accurate answer because complex deformation occurs in the microscopic shear area. Therefore, in this study, the effect of machining allowance on shaving processing was analyzed using the finite element method using high-strength steel plate (SPFH590), and the differences were compared and examined through actual experiments under the same conditions.

• Journal of Radiation Industry
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• v.17 no.2
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• pp.191-197
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• 2023

Abstract KOMAC(Korea Multi-Purpose Accelerator Complex, KAERI) has been operating a 100 MeV proton accelerator and is going to produce ⁶⁸Ga isotope which is useful for diagnosis of cancer. So, it is necessary to develop a transport container for radio-activated targets. In this study, we carry out shielding analysis and structural analysis for the radio-activated target transport container using simulation programs. According to the Type A standard, the transport container includes an inner container and an overpack container. The main material of inner container is lead, and the shape is cylindrical with diameter of 152mm, height of 142mm and weight about 29 kg. It is planned to verify the possibility of field application through production of the transport container prototype in the future.

• Structural Engineering and Mechanics
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• v.91 no.1
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• pp.87-102
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• 2024

In recent years, the focus on vibration analysis of multilayer smart structures has attracted considerable attention in many engineering applications. In this work, vibration analysis of a three-layer microporous beam with a core amplified by a composite material reinforced with graphene platelets and two piezoelectric thin films is discussed. It is assumed that piezoelectric layers with a thickness of 0.01 core are very thin and the properties of the matrix and reinforcement vary in the thickness directions. The governing equations of motion are obtained using an energy approach and the method of numerical differential quadrature to solve them. The results of this work are compared to other research and there is good agreement between them. The influences of the volumetric weight fraction of graphene wafers, different graphene platelets distributions, porosity distribution, mass scale parameters and thin ratio of graphene platelets take into account the natural dimensionless frequencies of the micro-beam. The results of this study show that the symmetric distribution of graphene platelets based on the symmetric porosity distribution has a great influence on the natural frequencies without basic dimension of the micro-beam, while the shape ratios of graphene platelets do not have a significant influence on natural frequency changes.

• Journal of Wind Energy
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• v.13 no.2
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• pp.31-41
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• 2022

The rated power and rotor diameters of wind turbines are significantly increasing for maximized energy production and minimized LCoE, especially for offshore wind turbines. Along with this, the loads and weight of rotor blades are inevitably increasing. Therefore, designers are striving to develop light structures by reducing unnecessary materials for the blades. However, designers have to develop a novel design concept to increase the critical buckling load since lightweight designs compromise the critical buckling load, which is frequently the critical design point for ultra-large wind turbine blades. In this paper, the concept of local reinforcement is introduced as a new structural design concept to increase the buckling load. Moreover, its verification procedure and modeling methodology were studied and verified by application to a 3 MW wind turbine blade.

• Geomechanics and Engineering
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• v.38 no.4
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• pp.397-408
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• 2024

Buried box culverts are crucial elements of transportation infrastructure. However, their behavior under foundation loads is not well understood, indicating a significant gap in existing research. This study aims to bridge this gap by conducting a detailed numerical analysis using the Finite Element Method and Abaqus software. The research evaluates the behavior of buried box culverts by examining their interaction with surrounding soil and the pressures from surface foundation loads. Key variables such as embedment depth, culvert wall thickness, concrete material properties, foundation pressure, foundation width, soil elastic modulus, and friction angle are altered to understand their combined effects on structural response. The methodology employs a validated 2D numerical model under plane strain conditions. Parametric studies highlight the critical role of culvert depth (H) in influencing earth pressure and bending moments. Foundation pressure and width demonstrate complex interdependencies affecting culvert behavior. Variations in culvert materials' elastic modulus show minimal impact. It was found that the lower wall of the buried culvert experiences higher average pressure compared to the other two walls, due to the combined effects of the culvert's weight and down drag forces on the side walls. Furthermore, while the pressure distribution on the top and bottom walls is parabolic, the pressure on the side walls follows a different pattern, differing from that of the other two walls.

• Computers and Concrete
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• v.34 no.3
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• pp.355-365
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• 2024

TECSolverApp is an application that calculates the total equivalent seismic load (base shear) and shows the design spectra in accordance with the Turkish Earthquake Code (TEC). TECSolverApp software can present the spectral acceleration-period graph and the base shear (in terms of unit building weight) in MATLAB and .NET Core frameworks according to TEC 2007 and TEC 2018. In the software, three different building period evaluation options were provided, as entering the period directly, empirical calculation, and using the period calculation formula. In different period calculation scenarios, particular design input parameters such as site-specific spectral acceleration coefficients, local soil class, building importance coefficient, and structural system behavior coefficient are expected. TECSolverApp was produced in two different programming languages and published in MATLAB App Designer and ASP.NET Core MVC environments. To be shared in MATLAB App Designer, it was aimed at availability through the program and distributability as a desktop application. By deploying in ASP.NET Core MVC, open-source cross-platform coding and web-based accessibility were targeted. One of the strongest aspects of TECSolverApp is its developability thanks to software architecture. In this respect, it can be foreseen that other international seismic codes can be added to the calculations in the future.

• Korean Journal of Food Science and Technology
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• v.27 no.6
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• pp.1017-1027
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• 1995

This study was attempted to investigate physicochemical properties, molecular structural properties of native and acid-treated chestnut starch and chestnut starch gel. The amylose content was 18.9% and X-ray diffraction pattern showed Cb type. Swelling power was increased abruptly in the range of $65^{\circ}C{\sim}75^{\circ}C$ but increased slowly after that and solubility was increased abruptly until $70^{\circ}C$ but increased slowly after that. In amylograms which have different heating temperatures, cooling viscosity at $50^{\circ}C$ was reduced as heating temperature was increased. In molecular structural properties of amylose, ${\lambda}_{max}$ was 640 nm, ${\beta}-amylolysis$ limit was 84.2% and the degree of polymerization was 951 and in those of amylopectin, ${\lambda}_{max}$ was 570 nm, ${\beta}-amylolysis$ limit was 58.2%, the degree of polymerization was 1371 and average chain length was 22.6. In gel chromatography elution profiles of starch and amylose, 4.0% and 11.5% of low molecular weight-molecules($<5{\times}10^5$) were leached out. In gel chromatography elution profiles of soluble starch, the higher heating temperature was, the more high molecular weight-starches were leached out. The elution profiles after debranching amylopectin with pullulanase showed 2.2 of the ratio of peakIII(DP 10-15) to peakII(DP 35-45). Acid hydrolysis extent of 2.2 N HCI-treated starch at $35^{\circ}C$ for 10 days was 96% and hydrolysis rate showed two step pattern which had border line at 4 days. In elution profiles of acid treated chestnut starch, amylopectin peak was disappeared compeletly after 6 hrs and converted short chains of DP 10-15. Amylose content was increased until 6 hrs but decreased after that. Hardness of starch gel made at $75^{\circ}C$ of heating temperature and cohesiveness of starch gel made at $85^{\circ}C$ of heating temperature were the highest. Retrogradation rate of starch gels were relatively high, especially for the starch gel made at $75^{\circ}C$ of heating temperature.

• Journal of the Korea institute for structural maintenance and inspection
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• v.17 no.3
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• pp.65-73
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• 2013

Recently the exterior attaching reinforcement method is being often used by using FRP (Fiber Reinforced Polymer) as a method of strengthening concrete structure. this FRP exterior attaching reinforcement method has several advantages like high intensity, stiffness, good durability and easy installment comparing to its weight. but its structure is airtight covered by reinforcement material whose water permeability is low and water can't be discharged, thus it may provoke a damage to the structure after a long while. the main purposes of this study are to develop GFRP reinforcement material which can discharge the surface water properly and to measure its special functions. for this, we have changed the normal reinforcement material to water permeable structure and measured its water permeance modulus by an indoor test which shows the process of water permeance with the parameter of contained GFRP quantity. also tried to verify the measured value of the water permeance modulus in theory by analyzing the numbers on water permeance process. the test result showed that the biggest quantity of water, 0.5129 g/h $m^2$ was discharged when the fiber contained quantity reached at 75% and the tensile strength was also biggest by 476.6MPa at 75%, so it appeared that COSREM GP panel with 75% fiber contained quantity is the best in ventilation and structure.