• Journal of the Earthquake Engineering Society of Korea
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• v.17 no.2
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• pp.79-88
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• 2013

Steel plate concrete (SC) composite structure is now being recognized as a promising technology applicable to nuclear power plants as it is faster and suitable for modular construction. It is required to identify its dynamic characteristics prior to perform the seismic design of the SC structure. Particularly, the damping ratio of the structure is one of the critical design factors to control the dynamic response of structure. This paper compares the criteria for the damping ratios of each type of structures which are prescribed in the regulatory guide for the nuclear power plant. In order to identify the damping ratio of SC shear wall, this study made SC wall specimens and conducted experiments by cyclic lateral load tests and vibration tests with impact hammer. During the lateral loading test, SC wall specimens exhibited large ductile capacities with increasing amplitude of loading due to the confinement effects by the steel plate and the damping ratios increased until failure. The experimental results show that the damping ratios increased from about 6% to about 20% by increasing the load from the safe shutdown earthquake level to the ultimate strength level.

• Transactions of the Korean Society of Mechanical Engineers
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• v.13 no.5
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• pp.875-885
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• 1989

This work is concerned with the chatter suppression by inserting viscoelastic materials into tool clamping area. Chatter was observed with and without the viscoelastic materials during cutting tests, where the overhang of the tool was made long so that the tool may be a major cause for the chatter. Two viscoelastic materials were used and the effects of thickness and prestrain were investigated. impact tests were performed on the tool in cases where the tool post was set on the cross slide and was free from any boundary conditions. Material properties of the viscoelastic materials were also obtained from resonance test results. The effects on the chatter suppression by the type of the viscoelastic material and prestrain are discussed in relation with the measured material properties.

• Geosciences Journal
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• v.22 no.6
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• pp.1041-1052
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• 2018

A single-well push-drift-pull tracer test using two different tracers ($SF_6$ and salt) was performed at the Environmental Impact Test (EIT) site to determine suitable locations for monitoring wells and arrange them prior to artificial $CO_2$ injection and leak tests. Local-scale estimates of hydraulic properties (linear groundwater velocity and effective porosity) were obtained at the study site by the tracer test with two tracers. The mass recovery percentage of the volatile tracer ($SF_6$) was lower than that of the non-volatile tracer (salt) and increased drift time may make degassing of $SF_6$ intensified. The $CO_2$ leakage monitoring results for both unsaturated and saturated zones suggest that the $CO_2$ monitoring points should be located near points at which a high concentration gradient is expected. Based on the estimated hydraulic properties and tracer mass recovery rates, an optimal $CO_2$ monitoring network including boreholes for monitoring the unsaturated zone was constructed at the study site.

• Design & Manufacturing
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• v.12 no.3
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• pp.48-54
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• 2018

This paper presents a numerical study for the development of a low-noise low-vibration industrial wheel for non-pneumatic wheel to significantly reduce vibration and noise. For this, design, injection molding and performance testing were performed. Various geometric shapes and materials were taken into account. For numerical analysis, ANSYS, LS-Dyna, and ABAQUS were used to predict the behavior of the wheel under different loadings based on various design changes. Based on this, 4 prototypes were fabricated by changing the design of wheels and molds, and various vibration and noise tests were carried out. A vibration tester was developed and tested to perform the vibration noise test considering durability. A prototype and test of the final wheel was performed. In the case of the vibration test, the vibration levels were 81.16dB and 80.66dB, which were below the target 90dB. Noise levels were 53.20 dB and 52.55 dB below the target 65dB. In the case of the impact resistance test, it was confirmed that there was no change in appearance after impact. The product weight was measured to be 174g compared to the target of 190g.

• International Journal of Naval Architecture and Ocean Engineering
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• v.11 no.1
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• pp.52-58
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• 2019

Marine emissions of Volatile Organic Compounds (VOCs) have received much attention because the International Maritime Organization (IMO) requires the installation of vapour emission control systems for the loading of crude oils or petroleum products onto ships. It was recently recognised that significant corrosion occurs inside these vapour emission control systems, which can cause severe clogging issues. In this study, we analysed the chemical composition of drain water sampled from currently operating systems to investigate the primary causes of corrosion in vapour recovery systems. Immersion and electrochemical tests were conducted under simulated conditions with various real drain water samples, and the impact of corrosion on the marine vapour recovery system was carefully investigated. Moreover, corrosion tests on alternative materials were conducted to begin identifying appropriate substitutes. Thermodynamic calculations showed the effects of environmental factors on the production of condensed sulphuric acid from VOC gas. A model of sulphuric acid formation and accumulation by the characteristics of VOC from crude oil and flue gas is suggested.

• Journal of Positioning, Navigation, and Timing
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• v.10 no.2
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• pp.103-111
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• 2021

A series of experiments have been carried out by using National Geographic Information Institute(NGII)'s Continuously Operating Reference Station (CORS) data with various strategies to analyze the impact of multi-GNSS measurements on baseline processing. The results of baseline processing were compared in terms of ambiguity fixing rate, precision, and hypothesis tests were conducted to confirm the statistical difference. The combination of multi-GNSS measurements has helped to improve ambiguity fixing rate, especially under harsh positioning environments. Combination of GPS, Galileo, BeiDou could get better precision than that of GPS, GLONASS, Galileo, and adding QZSS made the baseline solution's vertical component more precisely. The hypothesis tests have statistically confirmed that the inclusion of the multi-GNSS in the baseline processing enables not only to reduce field observation time length but also to enhance the solution's precision. However, it is of interest to notice that results of the baseline solution are dependent upon the software used. Hence, comprehensive studies should be performed shortly to derive the best practice to select the appropriate software.

• The Journal of Asian Finance, Economics and Business
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• v.9 no.9
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• pp.143-156
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• 2022

This article examines the effect of inward foreign direct investments (FDI) on the export performance of micro, small & medium enterprises (MSMEs) in India, and investigates the spillover impact and absorption capacity of the MSMEs sector. For the first time, the researchers applied the intersectoral linkage approach to investigate the matter and used a panel dataset between 2006 and 2017. The coefficients of forward and backward linkages are estimated by using the Rasmussen method, the study employs a basic linear panel data model, followed by various diagnostic tests to identify the problem of heteroscedasticity, autocorrelation / serial correlation, cross-sectional dependencies, multicollinearity, time-individual specific tests, and unobserved effects. The PCSE model was applied for robust standard error and the Hausman-Taylor IV model to check the robustness of the result generated in the linear panel data model. Despite the high prevalence of forward and backward intersectoral connections and the Lack of absorption capacity of local firms, the results show that FDI has little of an impact on the export performance of micro, small, and medium-sized businesses in India. This study adds to the existing literature on determining local firms' spillover effect and absorption capacity in response to inward FDI.

• The Journal of Asian Finance, Economics and Business
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• v.10 no.1
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• pp.181-187
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• 2023

The study aimed to study the effect of the inflation rate, the real domestic product, the interbank lending interest rate, and the total deposits on credit facilities in Jordan for 2012-2021 through quarterly data. The study adopted the ARDL model. The study used the time series analysis method, as the study tests the stationarity of the time series. The results showed that the impact of inflation on the total credit facilities was negative. In contrast, the impact of each of the total deposits, real GDP, and the interest rate of interbank loans on the total credit facilities was positive and significant. The study recommended the need for the banking sector in Jordan to develop risk management mechanisms in a way that allows it to adapt to economic cycles and crises by conducting stress tests and developing scenarios that ensure the formation of sufficient provisions to meet emergencies. The study also recommended that the macroeconomic policy should be based on creating a stable macroeconomic environment that allows the efficient employment of resources in all economic sectors in a way that achieves high economic growth rates, which contributes to the promotion of economic recovery and is reflected in income. Hence, individuals have a greater ability to repay loans.

• Journal of the Korea Safety Management & Science
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• v.25 no.4
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• pp.79-85
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• 2023

This study aims to verify the impact of a metaverse-based safety education program on the fire safety awareness of elementary school students. Utilizing the National Fire Agency's 119 metaverse program, an educational program was implemented for two months, and the experimental group was examined using paired-sample t-tests, while comparisons with the control group were made using independent-sample t-tests. The results revealed statistically significant differences between the experimental and control groups in the area of fire prevention. Although no statistically significant differences were observed over time within each group, the overall average scores for the entire class improved across all areas. Based on these findings, the effectiveness of metaverse-based safety education is suggested; however, a significant difference compared to traditional education was not detected. The study concludes by exploring implications for considerations in the implementation of metaverse safety education in the future.

• Structural Engineering and Mechanics
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• v.90 no.5
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• pp.493-504
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• 2024

This paper presents the methodology and results for the investigation of the structural safety of 40 aged underground water tanks to support the weight of photovoltaic (PV) systems that were supposed to be placed on their roof reinforced concrete (RC) slabs. The investigation procedure included (1) review of available documents; (2) visual inspection of the roof RC slabs; (3) carrying out a series of nondestructive (ND) tests; and (4) analysis of results. Out of the 40 tanks, eleven failed the visual inspection phase and were discarded from further investigation. The roof RC slabs of the tanks that passed the visual inspection were subjected to a series of ND tests that included infrared thermography, impact echo, ultrasonic pulse velocity (UPV), Schmidt hammer, concrete core compressive strength, and water-soluble chloride content. The NDT results proved that eight more tanks were not suitable to support the PV systems. Based on the results of the visual inspection and testing, a probabilistic decision-making criterion was established to reach a decision regarding the structural integrity of the roof slabs. The study concluded that the condition of the drainage filter was essential in protecting the tanks and its intact presence can be used as a strong indication of the structural integrity of the roof RC slabs.