• Structural Engineering and Mechanics
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• v.74 no.2
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• pp.255-266
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• 2020

The main requirements of modern welded metal structures are the load-carrying capacity (safety), fitness for production, and economy. The primary objective of attaching longitudinal stiffeners is to improve the buckling strength of relatively thin compression panels. This paper gives several comparisons for stiffened plates with different loadings (static, dynamic), different shape of stiffeners (flat, L-shape, trapezoidal), different steel grades, and different welding technologies (SMAW, GMAW, SAW), different costs to show the necessity of a combination of design, fabrication and economic aspects. Safety and fitness for production are guaranteed by fulfilling the design and fabrication constraints. The economy is achieved by minimizing the cost function. It is shown that the optimum sizes depend on the welding technology, the material yield stress, the profile of the stiffeners, the load cycles and the place of the production.

• JSTS:Journal of Semiconductor Technology and Science
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• v.10 no.1
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• pp.45-48
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• 2010

An inter-pin skew compensation scheme is proposed, which minimizes the inter-pin skew of parallel interface induced by unequal trace length and loading of printed circuit board (PCB). The proposed scheme measures the inter-pin skew and compensates during power-up with simple hardware. The proposed scheme is applied to 3.2-Gb/s/pin DDR4 SDRAM and implemented in a 0.18 m CMOS process. The inter-pin skew is compensated in 324-cycles of 400-MHz clock and the skew is compensated to be less than 24-ps.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.11a
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• pp.545-548
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• 2006

This study includes the experimental investigation on the fatigue-bond behavior with respect to the various rates of steel corrosion. Major criteria of test variables are the rates of steel corrosion by chloride ion and the ratio of the applied stress to the bond failure stress. According to the test results, the slip versus number of load cycles relation was found to be approximately linear in double logarithmic scale, not only without steel corrosion but also with steel corrosion. This research will be helpful for the realistic durability design and condition assessment of reinforced concrete structures.

• Proceedings of the Earthquake Engineering Society of Korea Conference
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• 2003.09a
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• pp.141-146
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• 2003

An experimental investigation was conducted to estimate the flexural behavior of circular concrete beams confined by carbon sheet tube under the loading and unloading cycles. Six specimens were produced with different layers of carbon sheets and with or without corrugations inside of tubes. The experimental results represented that the load and displacement capacity are increased in the specimens which have increased layers of tube and have installed corrugations inside of tubes. In order to obtain enough capacity, tubes have to keep tubes at proper layers but it can not affect positively more than certain layers to increase the layers of tube. Therefore, appropriate estimation of structural member is needed to obtain enough capacity and displacement by means of proper carbon sheet direction and layers of tube.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.955-963
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• 2008

There are lots of tunnel intervals in the KTX II stage construction line for the linearity of railway line passing mountain region. In order to use the rocks from tunnel excavations, railway subgrades are constructed with crushed rock-soil mixtures. In this study, plain strain test using large scale box was conducted in order to analyze the characteristics of deformation behavior of railway subgrades composed of crushed rock-soil mixtures. The effects of variation of degree of saturation, stress level of applied loadings, and number of loading cycles on the resilient and permanent deformation behavior were analyzed. The results show that degree of saturation have a great effect on the deformation behavior of crushed rock-soil mixtures. The axial strain ranges between $0.1{\sim}0.8%$ with variation of degree of saturation, in assumption that deviatoric stress applied on the subgrade by high-speed train load is 55kPa.

• Proceedings of the Korean Powder Metallurgy Institute Conference
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• 2006.09a
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• pp.181-182
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• 2006

Cylindrical specimens with different levels of density have been submitted to uniaxial compression tests with loading and unloading cycles. The analysis of the elastic loadings shows a non linear elasticity which can be mathematically represented by means of a potential law. Results are explained by assuming that the total elastic strain is the contribution of two terms one deriving from the hertzian deformation of the contacts among particles and another that takes into account the linear elastic deformation of the powder skeleton. A simple model based in an one pore unit cell is presented to support the mathematical model.

• Journal of Drive and Control
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• v.20 no.4
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• pp.54-63
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• 2023

High and intermittent loading cycles induce fatigue damage to transmission components, resulting in premature gearbox failure. To identify gearbox defects, numerous vibration-based diagnostics techniques, using several artificial intelligence (AI) algorithms, have recently been presented. In this paper, an optimized deep belief network (DBN) model for gearbox problem diagnosis was designed based on time-frequency visual pattern identification. To optimize the hyperparameters of the model, a particle swarm optimization (PSO) approach was integrated into the DBN. The proposed model was tested on two gearbox datasets: a wind turbine gearbox and an experimental gearbox. The optimized DBN model demonstrated strong and robust performance in classification accuracy. In addition, the accuracy of the generated datasets was compared using traditional ML and DL algorithms. Furthermore, the proposed model was evaluated on different partitions of the dataset. The results showed that, even with a small amount of sample data, the optimized DBN model achieved high accuracy in diagnosis.

• Journal of the Korea Concrete Institute
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• v.15 no.1
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• pp.17-24
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• 2003

One of the reasons for brittle failure in reinforced concrete structures subjected to severe earthquake is due to large local bond-slippage of bars resulting in fast bond degradation between reinforcing bars and concrete. This study aims to evaluate effects of bar deformation height on bond performance, specially, bond degradation under cyclic loading. Bond test specimens were constructed with machined bars with high relative rib areas. The degree of confinement by transverse bars is also another key parameters in this bond test. From test results, amounts of energy dissipation are calculated and compared for each parameter. Test results show that bond strength and stiffness drops significantly as cycles increases. The confinement and high relative rib area are effective to delay bond degradation, as the reduction of bond strength of cyclic loading compared to monotonic loading decreased for bars with large confinement and high relative rib areas. The energy dissipation also increases as the degree of confinement and relative rib area increases. However, tested bars with very high rib areas show that the bond may be damaged at relatively small slip because of high stiffness. The study will help to understand the bond degradation mechanism due to bar deformation height under cyclic loading and be useful to develop new deformed bars with high relative rib areas.

• Journal of Dental Rehabilitation and Applied Science
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• v.36 no.2
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• pp.95-103
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• 2020

Purpose: The purpose of this study was to compare the axial displacement of the hexagonal and conical abutment in internal conical connection implant after screw tightening and cyclic loading. Materials and Methods: Internal conical connection implants were divided into two groups (n = 10): group HEX, hexagonal abutment; and group CON, conical 2-piece abutments. The axial displacement and removal torque values were measured after 30 Ncm torque tightening and 250N loading test of 100,000 cycles. The Student t test with 5% significance level was used to evaluate the data. Results: HEX group demonstrated significantly higher axial displacement values after 30 Ncm tightening in comparison to the CON group (P < 0.05). No significant difference was found in axial displacement after cyclic loading (P = 0.052). Removal torque loss before and after the cyclic loading both revealed no significant difference between groups (P = 0.057 and P = 0.138). Removal torque value decreased after cyclic loading in both groups (P < 0.05). Conclusion: Overall, both abutment with or without hexagon index presented similar biomechanical performance except HEX group demonstrated significantly more axial displacement after applying tightening torque.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.7 no.1
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• pp.83-92
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• 1987

Fatigue fracture of reinforced concrete structures are characterized by considerably larger strains and microcracking as compared to fracture of R.C. structures under static loading. The strain of stirrup is increased suddenly by the occuring of inclined crack and the average strain ${\epsilon}_{\omega}$ of all stirrups in a structure at maximum load increase approximately in proportion to log N. The structures critical in longitudinal reinforcement seemed to have an endurance limit of 60~70 percent of static ultimate strengths for 1,000,000 cycles. In this test, the average fatigue strength at 1,000,000 cycles for all structures tested was approximately 65 percent of the static ultimate strength.