• Journal of the Society of Naval Architects of Korea
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• v.60 no.6
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• pp.460-472
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• 2023

This study was conducted based on the case of an accident (excessive deformation) that occurred during the hydraulic test of a shipboard tank manufactured in accordance with the design regulations. Over-pressure phenomenon was noted as the main cause of accidents in the process of testing tanks without physical damage, which can be found in external factors such as cross-sectional difference between inlet pipe and air pipe and higher water filling rate than the recommended one. The main goal of this paper is to establish a safe water filling rate according to the range of sectional area ratio(SAR) reduced below the regulations for each test situation. The simulation was conducted in accordance with the hydraulic test procedure specified in the Ship Safety Act, and the main situation was divided into two types: filling the tank with water and increasing the water head to the test pressure. The structural safety evaluation of the pressure generated inside the tank and the effect on the structure during the test was reviewed according to the SAR range. Based on the results, guidelines for the optimal filling rate applicable according to SAR during the hydraulic test were presented for the shipboard tanks used in this study.

• KIPS Transactions on Computer and Communication Systems
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• v.12 no.12
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• pp.357-362
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• 2023

Bridges are important transportation infrastructure, but they are subject to damage and cracking due to various environmental factors and constant traffic loads, which accelerate their aging. With many bridges now older than their original construction, there is a need for systems to ensure safety and diagnose deterioration. Bridges are already utilizing structural health monitoring (SHM) technology to monitor the condition of bridges in real time or periodically. Along with this technology, the development of intelligent bridge monitoring technology utilizing artificial intelligence and Internet of Things technology is underway. In this paper, we study an edge system technique for predicting bridge safety using fast Fourier transform and dimensionality reduction algorithm for maintenance of aging bridges. In particular, unlike previous studies, we investigate whether it is possible to form a dataset using sensor data collected from actual bridges and check the safety of bridges.

• Journal of the Korean Society of Radiology
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• v.12 no.1
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• pp.93-100
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• 2018

The fractional anisotropy value of the brain white matter region was analyzed by Tract-Based Spatial Statics(TBSS) method after acquiring the diffusion tensor image to identify the presence or absence of brain white matter damage to smoking in male. As a result, smokers showed lower fractional anisotropy than non-smokers in all areas but fractional anisotropy values were not statistically significant. the fractional anisotropy value, on the other hand, was statistically significant only for the right choroid plexus. In other words smoking, although, does not significantly affect the micro structural changes of brain white matter, it affects the choroid plexus area.

• Journal of Conservation Science
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• v.33 no.6
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• pp.399-416
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• 2017

The 'Wat Phou and Associated Ancient Settlements within the Champasak Cultural Landscape' of Laos was designated as a UNESCO World Cultural Heritage in 2001. The uppermost structure of the Sanctuary in Wat Phou has been destroyed and being variably damaged, maintenance is required through scientific and systematic diagnosis. The Sanctuary of Wat Phou was constructed mainly using sandstones and bricks. There are physical damages including fracture, break out, exfoliation and interval as well as biological damages by lichen, mosses and weeds. According to the ultrasonic velocity measurement and property evaluation of the sandstones of the Sanctuary in Wat Phou, weathering index of the eastern side sandstones is 0.10 to 0.74 (mean 0.36), showing MW grade. Southern and northern side sandstones have relatively higher properties with average weathering indices of 0.30 and 0.32. The results of slope analysis of the Sanctuary, indicated that the 4th spot in the southern side has the largest slope of $5^{\circ}W$, seemingly due to the unstable ground around the Sanctuary. Based on the relative level measurement and past drawings, the Sanctuary is verified to have been located on ground with a certain slope rather than flatland. The ground of the southern side is inclined $1.51^{\circ}$ more than that of the northern side, which will affect the structural stability of the temple. The interval width of the selected southern spot is the largest with an average width of 159.5 mm, and the largest width is 328.3 mm at the top, since the width increases above rather than below, seemingly due to the unequal subsidence of the ground. Constant maintenance for conservation is required for the structural stability of the Sanctuary in Wat Phou, which was partly collapsed and has also suffered physical damage.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.2
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• pp.377-387
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• 2014

This study mainly treats a new type of the bracing friction damper system, which is able to minimize structural damage under earthquake loads. The slotted bolt holes are placed on the shear faying surfaces with an intention to dissipate considerable amount of friction energy. The superelastic shape memory alloy (SMA) wire strands are installed crossly between two plates for the purpose of enhancing recentering force that are able to reduce permanent deformation occurring at the friction damper system. The smart recentering friction damper system proposed in this study can be expected to reduce repair cost as compared to the conventional damper system because the proposed system mitigates the inter-story drift of the entire frame structure. The response mechanism of the proposed damper system is firstly investigated in this study, and then numerical analyses are performed on the component spring models calibrated to the experimental results. Based on the numerical analysis results, the seismic performance of the recentering friction damper system with respect to recentering capability and energy dissipation are investigated before suggesting optimal design methodology. Finally, nonlinear dynamic analyses are conducted by using the frame models designed with the proposed damper systems so as to verify superior performance to the existing damper systems.

• Asian Pacific Journal of Cancer Prevention
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• v.13 no.11
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• pp.5391-5397
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• 2012

Background: Neuroblastoma (NB), like most human cancers, is characterized by genomic instability, manifested at the chromosomal level as allelic gain, loss or rearrangement. Genetics methods, as well as conventional and molecular cytogenetics may provide valuable clues for the identification of target loci and successful search for major genes in neuroblastoma. We aimed to investigate AURKA and MYCN gene rearrangements and the chromosomal aberrations (CAs) to determine the prognosis of neuroblastoma. Methods: We performed cytogenetic analysis by G-banding in 25 cases [11 girls (44%) and 14 boys (66%)] and in 25 controls. Fluorescence in situ hybridization (FISH) with AURKA and MYCN gene probes was also used on interphase nuclei to screen for alterations. Results: Some 18.4% of patient cells exhibited CAs., with a significant difference between patient and control groups in the frequencies (P<0.0001). Some 72% of the cells had structural aberrations, and only 28% had numerical chnages in patients. Structural aberrations consisted of deletions, translocations, breaks and fragility in various chromosomes, 84% and 52% of the patients having deletions and translocations, respectively. Among these expressed CAs, there was a higher frequency at 1q21, 1q32, 2q21, 2q31, 2p24, 4q31, 9q11, 9q22, 13q14, 14q11.2, 14q24, and 15q22 in patients. 32% of the patients had chromosome breaks, most frequently in chromosomes 1, 2, 3, 4, 5, 8, 9, 11, 12, 19 and X. The number of cells with breaks and the genomic damage frequencies were higher in patients (p<0.001). Aneuploidies in chromosomes X, 22, 3, 17 and 18 were most frequently observed. Numerical chromosome abnormalities were distinctive in 10.7% of sex chromosomes. Fragile sites were observed in 16% of our patients. Conclusion: Our data confirmed that there is a close correlation between amplification of the two genes, amplification of MYCN possibly contributing significantly to the oncogenic properties of AURKA. The high frequencies of chromosomal aberrations and amplifications of AURKA and MYCN genes indicate prognostic value in children with neuroblastomas and may point to contributing factors in their development.

• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.5
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• pp.94-100
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• 2017

In the case of the side scan sonar operated by the towing method, the underwater structure electric jig was developed because there is a difficulty in the cross-sectional survey that the user wants when conducting the survey. However, in the case of the sound wave photographing method using the electric jig, since the boat and the sonar behaves as one body, data distortion has occurred due to various problems according to working environment, such as, the rolling phenomenon of the boat due to the wave and the fluctuation of the sonic image due to the inoperability of the boat driver. Therefore, in order to solve the image blurring caused by the operation of the equipment for underwater survey of the existing side scan sonar, in this research, the program was supplemented to enable the shake correction by attaching the shake correction sensor and developing the shake correction algorithm. In order to verify the improvement of the sonar data resolution, the sonic images before and after the shake correction were collected through on-site investigation and the analysis of the sonic image data acquired by a diver measuring the actual damage length and depth. This study is expected to contribute to the development of sonar imaging technique of the underwater surface of the structure and bed surface of the sea or a river using the side scan sonar in the future.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.27 no.5
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• pp.315-323
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• 2015

Damage level of coastal structures has been scaled up according to increase of wave height and duration of the storm due to the abnormal global climate change. So, the design criteria for new breakwaters is being intensified and structural strengthening is also conducted for the existing breakwaters. Recently, interlocking concept has been much attention to enhance the structural stability of the conventional caisson structure designed individually to resist waves. The interlocking caisson breakwater may be survival even if unusual high wave occurs because the maximum wave force may be reduced by phase lags among the wave forces acting on each caisson. In this study, the dispersion characteristics of wave forces using interlocking system that connect the upper part of caisson with cable in the normal direction of breakwater was investigated. A simplified linear model was developed for computational efficiency, in which the foundation and connection cables were modelled as linear springs, and caisson structures were assumed to be rigid. From numerical experiments, it can be found that the higher wave forces are transmitted through the cable as the angle of incident wave is larger, and the larger the stiffness of the interlocking cable makes larger wave dispersion effect.

• Proceedings of the Korean Radioactive Waste Society Conference
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• 2009.06a
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• pp.84-85
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• 2009

New approaches for detecting, preventing and remedying environmental damage are important for protection of the environment. Procedures must be developed and implemented to reduce the amount of waste produced in chemical processes, to detect the presence and/or concentration of contaminants and decontaminate fouled environments. Contamination can be classified into three general types: airborne, surface and structural. The most dangerous type is airborne contamination, because of the opportunity for inhalation and ingestion. The second most dangerous type is surface contamination. Surface contamination can be transferred to workers by casual contact and if disturbed can easily be made airborne. The decontamination of the surface in the nuclear facilities has been widely studied with particular emphasis on small and large surfaces. The amount of wastes being produced during decommissioning of nuclear facilities is much higher than the total wastes cumulated during operation. And, the process of decommissioning has a strong possibility of personal's exposure and emission to environment of the radioactive contaminants, requiring through monitoring and estimation of radiation and radioactivity. So, it is important to monitor the radioactive contamination level of the nuclear facilities for the determination of the decontamination method, the establishment of the decommissioning planning, and the worker's safety. But it is very difficult to measure the surface contamination of the floor and wall in the highly contaminated facilities. In this study, the poly(styrene-ethyl acrylate) [poly(St-EA)] core-shell composite polymer for measurement of the radioactive contamination was synthesized by the method of emulsion polymerization. The morphology of the poly(St-EA) composite emulsion particle was core-shell structure, with polystyrene (PS)as the core and poly(ethyl acrylate) (PEA) as the shell. Core-shell polymers of styrene (St)/ethyl acrylate (EA) pair were prepared by sequential emulsion polymerization in the presence of sodium dodecyl sulfate (SOS) as an emulsifier using ammonium persulfate (APS) as an initiator. The polymer was made by impregnating organic scintillators, 2,5-diphenyloxazole (PPO) and 1,4-bis[5-phenyl-2-oxazol]benzene (POPOP). Related tests and analysis confirmed the success in synthesis of composite polymer. The products are characterized by IT-IR spectroscopy, TGA that were used, respectively, to show the structure, the thermal stability of the prepared polymer. Two-phase particles with a core-shell structure were obtained in experiments where the estimated glass transition temperature and the morphologies of emulsion particles. Radiation pollution level the detection about under using examined the beta rays. The morphology of the poly(St-EA) composite polymer synthesized by the method of emulsion polymerization was a core-shell structure, as shown in Fig. 1. Core-shell materials consist of a core structural domain covered by a shell domain. Clearly, the entire surface of PS core was covered by PEA. The inner region was a PS core and the outer region was a PEA shell. The particle size distribution showed similar in the range 350-360 nm.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.5
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• pp.150-159
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• 2011

The need of securing the stability and extending service lives by efficient maintenance of deteriorated tunnels for several decades has been increased. The stability and the usability of conventional tunnels can be decreased by change of physical properties of the surrounding ground, geometrical properties of the tunnel, an underground water level, environmental conditions, oxidation of lining and the breakdown of constituent materials. In respect of a long-term view, it is need to check all sorts of degradation, the degree of damage and durability to improve the serviceability and to come up with measures to maintain effectively. This paper is about study to analyze the stability of conventional tunnels(American Steel Support Method. ASSM). Three tunnels are chosen in those built in the 1930s and 1960s and the locations of tunnels are selected variously(ChungCheong, GyungBuk, GangWon, Jeolla, etc.) to secure reliability of this study. The state of repair and reinforcement of linings, cracks, and thickness and strength of lining of conventional tunnels in service are researched, compared and analyzed. The crack gauge, the GPR, the schmitt hammer was used for the crack investigation, cavitation, the strength respectively. By using these, the comparative analysis for conventional tunnels was conducted. As a result, there are more cracks in tunnels built in the 1930s than those of tunnels built in the 1960s, and lining strength of the 1930s is higher than those of the 1960s. The thickness of lining in tunnels built in the 1960s is higher than those in tunnels built in the 1930s. In proportion to thickness, cavitation occurred more frequently in tunnels built in the 1960s compared to those in tunnels built in the 1930s.