• Journal of the Korean Wood Science and Technology
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• v.52 no.3
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• pp.243-261
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• 2024

In this study, samples were collected from various ancient wooden shipwrecks, including the Shinan shipwreck and Jindo shipwreck that used iron nails, the Yeongheungdo shipwreck carrying iron artifacts, as well as the Sibidongpado shipwreck and Wando shipwreck where degradation products were not observed, all of which were salvaged by the National Research Institute of Maritime Heritage. The aim was to analyze the characteristics of degradation products generated by iron (Fe) within the salvaged wooden shipwreck materials and establish fundamental data on degradation products in waterlogged archaeological wood. The analysis revealed that sulfur (S) is generally accumulated in wood obtained from marine environments. It was observed that the content of inorganic substances such as iron and sulfur was significantly higher in the Shinan shipwreck, Jindo shipwreck, and Yeongheungdo shipwreck compared to Sibidongpado shipwreck and Wando shipwreck, which used wooden nails. This indicates that the presence of iron affects the accumulation of degradation products and suggests that iron is a factor in the corrosion of wood. Furthermore, crystallin compounds were observed within the cell walls, and higher concentrations of iron and sulfur were found in the resin ducts, rays, and radial tissues. This suggests that during desalination and consolidation treatments, warm water or polyethylene glycol (PEG) may move degradation factors into resincanals, rays, radial tissues, etc.

• Journal of Soil and Groundwater Environment
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• v.21 no.4
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• pp.1-9
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• 2016

Rehabilitation for low-yielding wells resulting in improvement on groundwater quantity and quality is considered to be the most economic and ecofriendly method against the increasing demand to groundwater due to frequent drought and the increase in numbers of agricultural complex for growing horticultural crops. This study suggests standard, stepwise diagnostic fuctions consisting of four steps (Basic inspection, Specific inspection, Rehabilitation, and Management) for an optimal management to the wells. Basic inspection can provide information on current groundwater quantity and quality compared with those on its initial stage. Specific-inspection based on hydrogeology can scientifically demonstrate causes of deterioration on groundwater quantity and quality. Results of specific inspection can suggest an optimal rehabilitation method to solve deteriorating problems including clogging and corrosion for the wells. After rehabiliating the wells, an assessment on groundwater quantity and quality would be conducted to identify the suitability of the applied method and improvement of the wells. A short-term, periodic management to the wells is considered as the key to save a public management budget. Suggested diagnostic functions can possibly induce sustainable supply of agricultural groundwater to the farm land and finally contribute the increase on rural household income.

• Journal of the Korean Applied Science and Technology
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• v.29 no.2
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• pp.317-322
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• 2012

The microstructures were examined by SEM, FT-IR spectra, tensible properties mole % of [NCO/OH], and particle size analyzer. Growing concerns in the environment-friendly industries have led to the development of solvent-free formulations that can be cured. We had synthesized the polyurethane resin having the ability to protect stainless steel against corrosion. Compared with general packing materials and coatings, this resin is highly stronger in intensity and longer durability. Polyurethane resins were composed of polyols, IPDI, silicone surfactant, catalyst and crosslink agent. Moreover, thermal fillers such as $Al_2O_3$, fume silica and $ZrO_2$ not only accelerated the curing rate but also improved the physical property as thermal barriers. The rigid segments of polyurethane in mechanical properties were due to crosslink agent and the increase of [NCO/OH]. In conclusion, the polyurethane microstructure with crosslink agent can be good material for themoset coating of metal substrates such as stainless steel.

• Journal of Korean Ophthalmic Optics Society
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• v.20 no.1
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• pp.9-14
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• 2015

Purpose: In this paper, the changes in eyeglasses frames were investigated when the frames were exposed to artificial sweat. Methods: The changes in surface, hardness, and tensile strength of eyeglasses frames made of nickel silver, Monel, and titanium were tested after the exposure to the artificial sweat of pH 6.5, 6.0, and 5.0, during 1, 3, and 6 week(s), for each. Results: Corrosion pattern of eyeglasses frames made of nickel silver, Monel, and titanium was induced by artificial sweat, and the patterns were different from another frame materials. In proportion to the pH of artificial sweat and exposure time to artificial sweat, hardness of all frames made of three different material decreased, however, tensile strength of the three frames was not changed. Conclusions: The necessity of routine management for eyeglasses frames can be suggested since the changes in surface corrosion and hardness of eyeglasses frames induced by sweat were shown.

• Smart Structures and Systems
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• v.26 no.2
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• pp.147-156
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• 2020

This numerical study demonstrates the porosity conditions and the intensity of the interactions with the aggressive agents. It is established that the density as well as the elastic modulus are correlated to ultrasonic velocity The following investigation assessed the effects of cement grade and porosity on tensile strength, flexural and compressive of Ultra High Performance Concrete (UHPC) as a numerical model in PLAXIS 2d Software. Initially, the existing strength-porosity equations were investigated. Furthermore, comparisons of the proposed equations with the existing models suggested the high accuracy of the proposed equations in predicting, cement grade concrete strength. The outcome obtained showed a ductile failure when un-corroded reinforced concrete demonstrates several bending-induced cracks transfer to the steel reinforcement. Moreover, the outcome also showed a brittle failure when wider but fewer transverse cracks occurred under bending loads. Sustained loading as well as initial pre-cracked condition during the corrosion development have shown to have significant impact on the corrosion behavior of concrete properties. Moreover, greater porosity was generally associated with lower compressive, flexural, and tensile strength. Higher cement grade, on the other hand, resulted in lower reduction in concrete strength. This finding highlighted the critical role of cement strength grade in determining the mechanical properties of concrete.

• Journal of Soil and Groundwater Environment
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• v.7 no.4
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• pp.40-47
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• 2002

The practices of the construction and management of the petroleum and hazardous chemical compound storage facilities in Korea were investigated extensively, and the problems were identified. The advanced technologies in the U.S.A were comparatively studied. Considering the effectiveness of leak prevention and applicability, the following measures were suggested. To prevent corrosion of a tank, a clad tank, an interior lining tank, or a double-wall tank were thought to be the most cost effective. For piping. use of non-metalic materials was suggested. A catchment basin seemed to be effective for preventing spills. For monitoring of leaks, constructions of more than one of detection systems, such as an automatic leak detection device. a vapor detection system, a groundwater monitoring system, or a double-wall monitoring system, were recommended.

• Nuclear Engineering and Technology
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• v.36 no.1
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• pp.112-120
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• 2004

The purpose of this paper is to analyze the piping failure frequency for the main feedwater system in domestic nuclear power plants(NPPs) for the application to an in-service inspection(ISI), leak before break(LBB) concept, aging management program(AMP), and probabilistic safety analysis(PSA). First, a database was developed for piping failure events in domestic NPPs, and 23 domestic piping failure events were collected. Among the 23 events, 12 locations of wall thinning due to flow accelerated corrosion(FAC) were identified in the main feedwater system in 4 domestic WH 3-loop NPPs. Two types of the piping failure frequency such as the damage frequency and rupture frequency were considered in this study. The damage frequency was calculated from both the plant population data and damage(s) including crack, wall thinning, leak, and/or rupture, while the rupture frequency was estimated by using both the well-known Jeffreys method and a new method considering the degradation due to FAC. The results showed that the damage frequencies based on the number of the base metal piping susceptible to FAC ranged from $1.26{\times}10^{-3}/cr.yr\;to\;3.91{\times}10^{-3}/cr.yr$ for the main feedwater system of domestic WH 3-loop NPPs. The rupture frequencies obtained from the Jeffreys method for the main feedwater system were $1.01{\times}10^{-2}/cr.yr\;and\;4.54{\times}10^{-3}/cr.yr$ for the domestic WH 3-loop NPPs and all the other domestic PWR NPPs respectively, while those from the new method considering the degradation were higher than those from the Jeffreys method by about an order of one.

• Advances in concrete construction
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• v.16 no.1
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• pp.69-78
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• 2023

This investigation delves into the adverse repercussions stemming from the impact of arsenic on steel pipes concealed within soil designated for rice cultivation. Simultaneously, the study aims to ascertain effective techniques for detecting arsenic in the soil and to provide strategies for mitigating the corrosion of steel pipes. The realm of nanotechnology presents promising avenues for addressing the intricate intersection of renewable energy, oil, and environmental pollution from a novel perspective. Nanostructured materials, characterized by distinct chemical and physical attributes, unveil novel pathways for pioneering materials that exert a substantial impact across diverse realms of food production, storage, packaging, and quality control. Within the scope of the food industry, the scope of nanotechnology encompasses processes, storage methodologies, packaging paradigms, and safeguards to ensure the safety of consumables. Of particular note, silver nanoparticles, in addition to their commendable antibacterial efficacy, boast anti-fungal and anti-inflammatory prowess, environmental compatibility, minimal irritability and allergenicity, resilience to microbial antagonism, thermal stability, and robustness. Confronting the pressing issue of arsenic contamination within both environmental settings and the food supply is of paramount importance to preserve public health and ecological equilibrium. In response, this study introduces detection kits predicated upon silver nanoparticles, providing an expeditious and economically feasible avenue for identifying arsenic concentrations ranging from 0.5 to 3 ppm within rice. Subsequent quantification employs Hydride Atomic Absorption Spectroscopy (HG-AAS), which features a detection threshold of 0.05 ㎍/l. A salient advantage inherent in the HG-AAS methodology lies in its capacity to segregate analytes from the sample matrix, thereby significantly reducing instances of spectral interference. Importantly, the presence of arsenic in the soil beneath rice cultivation establishes a causative link to steel pipe corrosion, with potential consequences extending to food contamination-an intricate facet embedded within the broader tapestry of renewable energy, oil, and environmental pollution.

• Nuclear Engineering and Technology
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• v.31 no.4
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• pp.375-384
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• 1999

The credibility of CHECWORKS FAC model analysis was evaluated for plant application in a model plant chosen for demonstration. The operation condition at each pipe component was defined before the wear rate analysis by plant data base, water chemistry analysis, and network flow analysis. The predicted wear was compared with the measured wear for 57 sample components selected from 43 susceptible line groups analysed. The inspected 57 locations represent components of highest predicted wear in each line group. Both absolute value and relative ranking comparisons indicated reasonable correlations between the predicted and the measured values. Four components showed much higher measured wear rates than the predicted ones in the feed water train from main feed water pump discharge to steam generator, probably due to high hydrazine concentration operation the effect of which had not been incorporated into the CHECWORKS model. The measured wear was higher than the predicted one consistently for components with least susceptibility to FAC. It is believed that the conservatism maintained during UT data analysis dominated the measurement accuracy. A great deal of enhancement is anticipated over the current plant pipe management program when a comprehensive plant pipe management program is implemented based on the model analysis.

• 한국신재생에너지학회:학술대회논문집
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• 2011.11a
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• pp.81.2-81.2
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• 2011

The gas diffusion layer (GDL) consists of two main parts, the GDL backing layer, called as a substrate and the micro porous layer (MPL) coated on the GDBL. In this process, carbon particles of MPL penetrates to the GDBL consequently forms MPL penetration part. In this study, the micro porous layer (MPL) penetration thickness is determined as a design parameter of the GDL which affect pore size distribution profile through the GDL inducing different mass transfer characteristics. The pore size distribution and water permeability characteristics of the GDL are investigated and the cell performance is evaluated under fully/low humidification conditions. Transient response and voltage instability are also studied. In addition, to determine the effects of MPL penetration on the degradation, the carbon corrosion stress test is conducted. The GDL that have deep MPL penetration thickness shows better performance in high current density region because of enhanced water management, however, loss of penetrated MPL parts is shown after aging and it induces worse water management characteristics.