• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3548-3556
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• 2015

In order to fulfill the needs of reliable and economically feasible foundation, engineers should consider not only the working load that can endure extreme conditions but also apprehending precise behavior of continuous dynamic load while designing the foundation of offshore wind power generators. To actualize the foundation, a model pile was made in miniature. Also, calibration chamber was made and a 500mm height of sand-bed was made to perform "static lateral load experiment" and "repetitive loading experiment", total of two Lateral load tests. As a result, in Static Lateral load test, the bigger length/diameter of model pile led an increase in load displacement. However, when performing "Cyclic Lateral load test", the increase in number of under loading led the decrease in horizontal displacement from each repeated lateral load. While performing Static Lateral load test and repeated loading experiment, we could observe the decreasing in the rate of ultimate lateral load capacity increase of the pile. Also, it turned out that the higher relative density of the ground, the lower ultimate lateral load capacity by repeated horizontal loading.

• Journal of the Korea institute for structural maintenance and inspection
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• v.24 no.3
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• pp.112-121
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• 2020

In suspension bridges, hanger cables are the main load-supporting members. The tension of the hanger cables of a suspension bridge is a very important parameter for assessing the integrity and safety of the bridge. In general, indirect methods are used to measure the tension of the hanger cables of a suspension bridge in traffic use. A representative indirect method is the vibration method, which extracts modal frequencies from the cables' responses and then measures the cable tension using the cables' geometric conditions and the modal frequencies. In this study, the image processing technique is applied to facilitate the estimation of the dynamic responses of the cables using the image signal, for which a portable digital camcorder was used due to its convenience and cost-efficiency. Ambient vibration tests were conducted on a suspension bridge in traffic use to verify the validity of the back analysis method, which can estimate the tension of remote hanger cables using the modal frequencies as a parameter. In addition, the tension estimated through back analysis method, which was conducted to minimize the difference between the modal frequencies calculated using finite element analysis of the hanger cables and the measured modal frequencies, was compared with that measured using the vibration method.

• Journal of Radiation Industry
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• v.11 no.1
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• pp.1-6
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• 2017

Reported some level of bacteria in areas that are well made contact in Radiology imaging room evaluate the importance of cleanliness in the hospital management of equipment to check for the presence of pathogenic bacteria. Gwang-ju and Jeol-la city and medium-sized hospitals in the material with a cotton swab and rub evenly Radiology selection cassette, a handle, Apron of the imaging apparatus having the most contact with patients from July 2016 to August 2016 as a target in place and special studios 6, and saline solution will placed in a test tube containing. The swab sample was diluted 1,000 times, you can see the bacteria and the intestinal bacterial selective medium Trypticase Soy Agar (TSA), Muller-Hinton Agar (MHA), Eosin-Methylene Blue (EMB), ENDO(BD, NJ, USA) then incubated smear to. In the incubator (incubator, SANYO, Japan) was observed after incubation of bacteria and counting the total number of bacteria also Colonies (colony) suspected intestinal bacteria were isolated and cultured on KIA medium (BD, NJ, USA). As a result, it was found that this came Gram positive Coccus A hospital handle the F hospital, from the C Gram positive Coccus cassette and handle the F hospital. The striking yellow coloring Staphylococcus aureus 110 agar (STA 110) in the medium sample, but it is suspected staphylococcal Coccus to the final identification in the laboratory is not a single specimen of the two samples from Gram positive Coccus biochemical identification Identification Kit is an API could not, it was thought to be non-Staphylococcus aureus was cultured on blood agar suggesting that (BAP) blood of dance. Dynamic tests were conducted biochemical API kit of the two samples were identified from Gram positive Coccus bacteria Escherichia coli (E. coli) is F hospital cassette was confirmed Eenterobacter cloaca in A hospital possession. Did not aggregate O-26, O-111, O-157 and the serum test was conducted in the laboratory from the E. coli F cassette hospital.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.993-999
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• 2008

A girder height limitation is the critical parameter for rapid construction of bridge deck and construction space limitation especially in urban area such as high population area and high density habitats. A standard post-tensioned I-shaped concrete girder usually demands relatively higher girder height in order to retain sufficient moment arm between compression force and tensile force. To elaborate this issue, a small U-shaped section with wide flanges can be used as a possible replacement of I-shaped standard girder. This prestressed concrete box girder allows more flexible girder height adjustment rather than standard I-shaped post-tensioned girder plus additional torsion resistance benefits of closed section. A 30m-long, 1.7m-high and 3.63m-wide actual small prestressed concrete box girder is designed and a laboratory test for its static behaviors by applying 6,200kN amount of load in the form of 4-point bending test was performed. The load-deflection curve and crack patterns at different loading stage are recorded. In addition, to extracting the dynamic characteristics such as natural frequency and damping ratio of this girder, several excitation tests with artificial mechanical exciter with un-symmetric mass are carried out using operational frequency sweep-up. Nonlinear finite element analysis of this 4 point bending test under monotonic static load is investigated and discussed with aids of concrete damaged plasticity formulation using ABAQUS program.

• Nuclear Engineering and Technology
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• v.53 no.9
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• pp.3068-3084
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• 2021

Investigations of large commercial aircraft impact effect on nuclear power plant (NPP) buildings have been drawing extensive attentions, particularly after the 9/11 event, and this paper aims to experimentally assess the damage and vibrations of NPP buildings subjected to aircraft crash. In present Part I, two shots of reduce-scaled model test of aircraft impacting on NPP building were carried out. Firstly, the 1:15 aircraft model (weighs 135 kg) and RC NPP model (weighs about 70 t) are designed and prepared. Then, based on the large rocket sled loading test platform, the aircraft models were accelerated to impact perpendicularly on the two sides of NPP model, i.e., containment and auxiliary buildings, with a velocity of about 170 m/s. The strain-time histories of rebars within the impact area and acceleration-time histories of each floor of NPP model are derived from the pre-arranged twenty-one strain gauges and twenty tri-axial accelerometers, and the whole impact processes were recorded by three high-speed cameras. The local penetration and perforation failure modes occurred respectively in the collision scenarios of containment and auxiliary buildings, and some suggestions for the NPP design are given. The maximum acceleration in the 1:15 scaled tests is 1785.73 g, and thus the corresponding maximum resultant acceleration in a prototype impact might be about 119 g, which poses a potential threat to the nuclear equipment. Furthermore, it was found that the nonlinear decrease of vibrations along the height was well reflected by the variations of both the maximum resultant vibrations and Cumulative Absolute Velocity (CAV). The present experimental work on the damage and dynamic responses of NPP structure under aircraft impact is firstly presented, which could provide a benchmark basis for further safety assessments of prototype NPP structure as well as inner systems and components against aircraft crash.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.4
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• pp.83-91
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• 2021

In this study, to improve the connection performance between the existing reinforced concrete (R/C) frame and the strengthening member, we proposed a new H-section steel frame with elastic pad (HSFEP) system for seismic rehabilitation of existing medium-to-low-rise reinforced concrete (R/C) buildings. This HSFEP strengthening system exhibits an excellent connection performance because an elastic pad is installed between the existing structure and reinforcing frame. The method shows a strength design approach implemented via retrofitting, to easily increase the ultimate lateral load capacity of R/C buildings lacking seismic data, which exhibit shear failure mechanism. Two full-size two-story R/C frame specimens were designed based on an existing R/C building in Korea lacking seismic data, and then strengthened using the HSFEP system; thus, one control specimen and one specimen strengthened with the HSFEP system were used. Pseudodynamic tests were conducted to verify the effects of seismic retrofitting, and the earthquake response behavior with use of the proposed method, in terms of the maximum response strength, response displacement, and degree of earthquake damage compared with the control R/C frame. Test results revealed that the proposed HSFEP strengthening method, internally applied to the R/C frame, effectively increased the lateral ultimate strength, resulting in reduced response displacement of R/C structures under large scale earthquake conditions.

• Applied Chemistry for Engineering
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• v.30 no.4
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• pp.435-444
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• 2019

In this study, two types of nonionic saccharide biosurfactants, GP-6 and GP-7, were prepared from coconut oil and the structure of resulting products was investigated by FT-IR, $^1H-NMR$ and $^{13}C-NMR$ spectrophotometer. The interfacial properties of GP-6 and GP-7 were found to be excellent from interfacial property measurements such as critical micelle concentration, static and dynamic surface tensions, interfacial tension, emulsification power, wetting property and foam stability. Detergency test evaluated by using a Terg-o-tometer showed moderately good detergency compared to that of conventional surfactants used in detergent formulations. Biodegradability, acute oral toxicity, acute dermal irritation and acute eye irritation tests revealed that both surfactants possess excellent mildness and superior environmental compatibility indicating the potential applicability to detergent products formulations. In particular, GP-6 can be considered as a strong candidate in detergent formulations since it is more surface active, mild and readily biodegradable than GP-7.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.41 no.1
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• pp.21-28
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• 2021

The main purpose of this study is to assess the safety of the fixed anchorages subjected to the seismic motion for an operating facilities in the actual power plant. Thus, the experimental study was conducted to investigate the load response in the event of an actual seismic to the anchorages of a nonstructural components. Since there are economic and spatial constraints to study nonstructural components that actually have various forms, alternative test specimens of steel frames with mass were built and the shaking table test was carried out. In order to evaluate the dynamic characteristics and seismic performance, the natural frequency of the target structure was identified through the shaking table test and then the load response characteristics of the anchorage were evaluated by generating an artificial seismic effect like actual seismic. Finally, the structural stiffness was reinforced by fixing the steel frame to the test specimen using bolts, thereby reducing the load transmitted to the anchorage. It will be carried out on the reliability verification of the experiments and areas that have not been carried out due to the site conditions through the analytical approach in the future.

• International Area Studies Review
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• v.21 no.4
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• pp.223-245
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• 2017

This study is examined interaction between carbon market with stock market using a multivariate GARCH(DCC) model. Carbon market is EU ETS EUA price, stock market is the iron and cement stock price which has relatively energy intensive and massive carbon emissions sector in the industrial sector. It also analyzed changes in the correlation between the markets through an analysis of correlation coefficients. Moreover, it checked whether there was marketability expansion(or expansion of carbon emissions reduction) through the analysis above. As a result of empirical tests, it showed that the price spillover effect was insignificant. In addition, it represented that there was a weak correlation between the two markets since the volatility spillover effect disappeared in the second phase by an external shock(a financial crisis). Moreover, it was revealed that there were no significant changes although there was a weak upward trend in terms of the correlation between the carbon market and the stock market. This implies that emission rights could not expand marketability to financial market as a commodity(or did not play its natural role of the reduction of carbon emission).

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.50 no.3
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• pp.181-192
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• 2022

Active vibration control system(AVCS) for helicopter enables to control the vibration generated from the main rotor and has the superb vibration reduction performance with low weight compared passive vibration reduction device. In this paper, FxLMS algorithm-based vibration control software of the light civil helicopter tansmits the control command calculated using the signals of the tachometer and accelerometers to the circular force generator(CFG) is developed and verified. According to the RTCA DO-178C/DO-331, the vibration control software is developed through the model based design technique, and real-time operation performance is evaluated in PILS(processor in-the loop simulation) and HILS(hardware in-the loop simulation) environments. In particular, the reliability of the software is improved through the LDRA-based verification coverage in the PIL environments. In order to AVCS to light civil helicopter(LCH), the dynamic response characteristic model is obtained through the ground/flight tests. AVCS configuration which exhibits the optimal performance is determined using system optimization analysis and flight test and obtain STC certification.