• Journal of the Korean Society of Marine Environment & Safety
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• v.20 no.6
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• pp.730-737
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• 2014

In this study, chloride content of marine concrete bridge at the south coast in 5~34years was calculated based on the measured data and the validity of the proposed value was evaluated. Also, correlation of existence of salt injury prevention coating, chloride content, carbonation depth and the compressive strength of marine concrete bridges were derived and relationship of the four was evaluated. According to the research results, surface chloride content value in the tidal zone proposed form KCI 2009 and value in the splash zone and atmospheric zone proposed form Cheong et al.(2005) was the most valid. Also, salt injury prevention coating of marine concrete bridges had the outstanding effect of preventing chloride content penetration, carbonation depth and reduction in the compressive strength. Compressive strength of concrete was reduced by the increase of carbonation depth and chloride content.

• Journal of the Korean Society of Safety
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• v.32 no.6
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• pp.54-60
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• 2017

A railway rail will be corroded by the repetitive sea wind and fog in the splash and tidal zone such as Youngjong grand bridge. And these rusts of rail could be increased by increasing service period, and it frequently occurred the safety accidents or disorders in electrical problem. In this study, the sacrificial anode cathodic protection method was proposed as a measures for reducing the corrosion of the railway rails in the oceanic climate conditions. As the results of immersion test using the salt water during four months, the sacrificial anode cathodic protection method using the aluminum anode(Al-anode) was evaluated that a distinct effect on corrosion reduction in the rails. Therefore the sacrificial anode cathodic protection method was experimentally proven that a disorders in aspects electric and signal of railway operation condition such as direct fixation track system in Youngjong grand bridge could be prevented by reducing rust falling from the rail. In addition, the installation conditions of the anodes directly affect the transmission range of corrosion potential, the sectional loss of anode, and the corrosion reduction effect. Therefore, to expect the corrosion reduction effect of rails under the oceanic climate conditions for railway track, it was important to adopted the appropriate spacing of anode installation by considering the actual field conditions.

• Journal of Technologic Dentistry
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• v.34 no.4
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• pp.345-352
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• 2012

Purpose: The age-hardening mechanism of an Au-Ag-Cu-Pt-Zn alloy for crown and bridge fabrication was investigated by means of hardness test, X-ray diffraction study and field emission scanning electron microscopic observation. Methods: Before hardness testing, the specimens were solution treated and then were rapidly quenched into ice brine, and were subsequently aged isothermally at $400-450^{\circ}C$ for various periods of time in a molten salt bath and then quenched into ice brain. Hardness measurements were made using a Vickers microhardness tester. The specimens were examined at 15 kV using a field emission scanning electron microscope. Results: By the isothermal aging of the solution-treated specimen at $450^{\circ}C$, the hardness increased rapidly in the early stage of aging process and reached a maximum hardness value. After that, the hardness decreased slowly with prolonged aging. However, the relatively high hardness value was obtained even with 20,000 min aging. By aging the solution-treated specimen, the f.c.c. Au-Ag-rich ${\alpha}_0$ phase was transformed into the Au-Ag-rich ${\alpha}_1$ phase and the AuCu I ordered phase. Conclusion: The hardness increase in the early stage of aging process was attributed to the formation of lattice strains by the precipitation of the Cu-rich phase and then subsequent ordering into the AuCu I-type phase. The decrease in hardness in the later stage of aging process was due to the release of coherency strains by the coarsening of tweed structure in the grain interior and by the growth and coarsening of the lamellar structure in the grain boundary. The increase of inter-lamellar space contributed slightly to the softening compared to the growth of lamellar structure toward the grain interior.

• Corrosion Science and Technology
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• v.6 no.6
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• pp.269-274
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• 2007

The corrosion of steel in concrete is significant in marine environment. Salt damage is one of the most detrimental causes to concrete bridges and port structures. Especially, the splash and tidal zones around water line are comparatively important in terms of safety and life-time point of view. During the last several decades, cathodic protection (cp) has been commonly accepted as an effective technique for corrosion control in concrete structures. Zn-mesh sacrificial anode has been recently developed and started to apply to the bridge column cp in marine condition. The detailed parameters regarding Zn-mesh cp technique, however, have not well understood so far. This study is to investigate how much Zn-mesh cp influences along the concrete column at elevated temperature. About 100 cm column specimens with eight of 10 cm segment rebars have been used to measure the variation of cp potential with the distance from Zn-mesh anode at both $10^{\circ}C$ and $40^{\circ}C$ in natural seawater. The cp potential change and current diminishment along the column specimens have been discussed for the optimum design of cp by Zn-mesh sacrificial anode.

• BMB Reports
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• v.45 no.12
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• pp.748-753
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• 2012

A sequence of 10 amino acids at the C-terminus region of methylglyoxal synthase from Escherichia coli (EMGS) provides an arginine, which plays a crucial role in forming a salt bridge with a proximal aspartate residue in the neighboring subunit, consequently transferring the allosteric signal between subunits. In order to verify the role of arginine, the gene encoding MGS from a thermophile species, Thermus sp. GH5 (TMGS) lacking this arginine was cloned with an additional 30 bp sequence at the 3'-end and then expressed in form of a fusion TMGS with a 10 residual segment at the C-terminus ($TMGS^+$). The resulting recombinant enzyme showed a significant increase in cooperativity towards phosphate, reflected by a change in the Hill coefficient (nH) from 1.5 to 1.99. Experiments including site directed mutagenesis for Asp-10 in TMGS and $TMGS^+$, two dimentional structural survey, fluorescence and irreversible thermoinactivation were carried out to confirm this pathway.

• Transactions of the Korean hydrogen and new energy society
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• v.18 no.2
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• pp.151-156
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• 2007

Solar cell and nanofiltration membrane were utilized in a system of enzymatic hydrogen production through light-sensitized photoanode, which resembles photoelectrochemical(PEC) configuration. Solar cell uses no additional light energy to increase energy for electrons to reduce protons and for holes to oxidize water to oxygen, and nanofiltration membrane replaces a salt bridge successfully with increased ion transport capability. With this system configuration, optimized amount of enzyme(10.98 unit), and an anodized tubular $TiO_2$ electrode($5^{\circ}C$/1 hr in 0.5 wt% HF-$650^{\circ}C$/5 hr) hydrogen evolved at a rate of ca. $43\;{\mu}mol/(cm^2{\times}hr)$ in a cathodic compartment and oxygen generated at a rate of ca. $20\;{\mu}mol/(cm^2{\times}hr)$ in an anodic compartment. The stoichiometric evolution of gases indicated that water was splitted in the system.

• Journal of the Korean Society of Food Culture
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• v.33 no.5
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• pp.426-436
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• 2018

This study assessed effective strategies to reduce the sodium intake among consumers using pork cutlet sauce as a model food system. Original pork cutlet sauce and sodium-reduced sauce (29% reduced by a salt substitute) were analyzed to characterize the sensory properties using descriptive analysis. The effects of sodium-reduction of the sauce, consumer type (nutrition teachers vs. general consumers), information related to the sodium content, serving method, and consumer's health, taste and sodium-related attitudes on the consumer's preference, perception, and intake of the sauce were analyzed using a consumer test. In descriptive analysis, the original and sodium-reduced sauce showed similar sensory characteristics but did not differ in saltiness. In the consumer test, there were no significant differences in the overall preference levels between the two sauces. On the other hand, there were significant differences in preference and perception between nutrition teachers and general consumer groups, which were due largely to their age as well as the health and sodium-related attitudes and nutritional knowledge differences. Sodium-reduced information decreased the perceived saltiness intensity. In addition, reducing sodium intake by serving pork cutlet sauce in a bottle can be an effective strategy because this serving method increased the acceptance and induced the smaller intake of sauce.

• Journal of Ocean Engineering and Technology
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• v.32 no.5
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• pp.361-366
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• 2018

The present study analyzed the variation factors in inducing a salinity change using the existing observation network in the section between the Nakdong River Estuary Barrage and Changnyeong-Haman Weir, and also examined the seasonal changes in precipitation, salinity, and discharge. Furthermore, this study analyzed the causes of a salinity increase by collecting observational data during a period when abnormal salinity occurred, and further investigated the salinity transfer time in a section of approximately 5.3 km from the Nakdong River Estuary Barrage to Nakdong River Bridge to understand the behavioral characteristics of the salinity moving upstream. The study results would make it possible to control the increase in salinity and block salt water from moving upstream by understanding the salinity variation characteristics according to the discharge amount. This will provide stability in collecting water from various residential, agricultural, and industrial sources through water intake facilities scattered near the Nakdong River Estuary Barrage.

• Journal of the Korean Institute of Landscape Architecture
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• v.30 no.2
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• pp.70-78
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• 2002

The landscape disign of Gamcheon wholesale fish Market was designed around a turnkey base to promote the economy of Busan Metropolitan City, to establish a fishery marketing center and to modernize existing facilities. The objectives of the project were to promote the mood of an old market, while preserving its functions and efficiency as a market, to design outdoor spaces with natural resources and amenities in balance, and to create attractive tourist spots in connection with the wide area development plan. The project was oriented, fast, to enhance the functions of the market. For this purpose, a multi-dimensional space layout was designed in consideration of functions as a wholesale market. The safety of pedestrians was secured by separating lathes for vehicles and for pedestrians. Tree planting with various functions such as sheltering, wind breaking and guiding was planned. Secondly, nature-friendly and human-friendly landscaping design was attempted. For this, the beautiful natural resources of Amnam Park were utilized, and green spaces such as green bridges linking buildings in the wholesale market, and rooftop gardens were to be arranged. In addition, environment-friendly facilities such as roads paved with natural materials(i.e. gravel, shells) and program parking lots were to be planned. Thirdly, landscape design was considered to create attractive tourist spots. For example, a fish farm was created as a theme street for pedestrians and various water-friendly spaces such as pedestrian ramps, observatories and seaside streets were to be secured. The main contents are as follows. First, a green bridge to Ahnnam Park was introduced for a tour source and flower garden, an event plan and viewing deck open to the sea were planned on the bridge's axis. Secondly, for the effective land use plan concerning open space and convenience to visitors, a promenade was planned, which is connected with the theme plaza and small plazas by environmental sculptures in front of the market hall and at the gate. As well, an observatory and a roof garden help create three dimensional multi leveled space, with a good view of the natural landscape of the sea, sky and park Thirdly, landscape materials, such as trees and those for facilities, strengthened for protection against the seawind and salt damage were selected. The commercial market area was intended to be transformed a traditional functional area of efficiency and economy into an attractive marine leisure area where both tourists and neighbors can make use of it.

• Journal of the Korea Concrete Institute
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• v.15 no.3
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• pp.400-408
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• 2003

Chloride ion inside concrete destroys the so-called passive film surrounding reinforcing bars inside concrete so that the so-called salt attack accelerates corrosion which is the most critical factor for durability as well as structural safety of reinforced concrete structures. Recently, as a solution of the salt attack, the ground granulated blast-furnace slag(GGBFS) have been used as binder or blended cement more extensively. In this paper, characteristics of chloride ion diffusion for the GGBFS concrete, which is known to possess better resistance to damage due to the chloride ion penetration than ordinary portland cement(OPC) concrete possesses, are analyzed and a chloride ion diffusion model for the GGBFS concrete is proposed by modifying an existing diffusion model for the OPC concrete. The proposed model is verified by comparing diffusion analysis results using the model accelerated chloride penetration test results for concrete specimens as well as field test results for an RC bridge pier. Then, an optimal resistance condition to chloride penetration for the GGBFS concrete is obtained according to degrees of fineness and replacement ratios of the GGBFS concrete. The result shows that the GGBFS concrete has better resistance to chloride ion penetration than OPC concrete has and the resistance is more affected by the replacement ratio than the degree of fineness of the GGBFS.