• Journal of Advanced Marine Engineering and Technology
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• v.34 no.5
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• pp.670-677
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• 2010

There are many surface protection methods for numerous steel structures being used under severely corrosive environment, one of them, metallizing(thermal spray) is a available protection method which is comparatively and recently developed for surrface protection of various steel structures. However coating film obtained by spraying is to be needed increasingly more good corrosion resistance due to accelerating of environmental contamination. In this study, coating films(DFT:$200{\mu}m$) are performed with arc spray by wire metal and their types of films are pure zinc, pure aluminum, alloy film(Al:Zn=85:15) and alloy film(Al:Zn=95:5). And corrosion resistance of their films was investigated with electrochemical methods in seawater solution. Pure aluminum film showed a relatively somewhat good corrosion resistance compared to among those of other films and alloy films also showed a good corrosion resistance compared to pure zinc film. Especially it was observed that pure aluminum film showed a comparatively good corrosion resistance than that of alloy film named as galvarium spray(Al:Zn=85:15) in seawater solution. Morphology of corroded surface of pure zinc film appeared the pattern like intergranlar corrosion, however films of pure aluminum and alloy metal showed a general corrosion pattern.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.37 no.5
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• pp.481-488
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• 2013

Nitric oxide ($NO_x$) formation characteristics in non-premixed diffusion flames of methane fuels have been investigated experimentally and numerically by adding 10% ammonia to the fuel stream, according to the variation of the oxygen ratio in the oxidizer with oxygen/carbon dioxide and oxygen/nitrogen mixtures. In an experiment of coflow jet flames, in the case of an oxidizer with oxygen/carbon dioxide, the $NO_x$ emission increased slightly as the oxygen ratio increased. On the other hand, in case of an oxygen/nitrogen oxidizer, the $NO_x$ emission was the maximum at an oxygen ratio of 0.7, and it exhibited non-monotonic behavior according to the oxygen ratio. Consequently, the $NO_x$ emission in the condition of oxyfuel combustion was overestimated as compared to that in the condition of conventional air combustion. To elucidate the characteristics of $NO_x$ formation for various oxidizer compositions, 1D and 2D numerical simulations have been conducted by adopting one kinetic mechanism. The result of 2D simulation for an oxidizer with oxygen/nitrogen well predicted the trend of experimentally measured $NO_x$ emissions.

• Asian Journal of Turfgrass Science
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• v.24 no.2
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• pp.199-204
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• 2010

Much of the coal ash by thermal power plant has gradually been increased, however researches on the recycling of bottom ash has not been investigated enough so far. In this research, the lysimeter test was conducted to find out the possibilities of bottom ash as soil amendment to improve the physiochemical properties of sandy topsoil of turfgrass in golf course. The turfgrass growth test and leaching test were conducted on the lysimeter. The lysimeter columns were manufactured with various topsoil mixing ratios of 0, 10, 20, 30, and 50% of bottom ash with sand. As a result of leachate analysis through the lysimeter column, the higher ratios of bottom ash mixed affect significantly on water holding capacity of topsoil sand media with decreasing of the percolation rate. The results of leachate analysis in every three days interval, the pH of leachate increased with the bottom ash ratios, but the volume of $NO_3$-N, $NH_4$-N and K decreased significantly. However, the level of EC of leachate had constantly maintained. These results indicate that the application of bottom ash may improve turfgrass growth with water holding capability and fertility of sandy topsoil. However, the negative effects of the bottom ash also evaluated by reducing water permeability and solubility of $PO_4$-P by adsorption into soil particles. The results indicates that the reasonable mixing ratio of the bottom ash as soil amendment should be less than 20% (v/v) with sand which has a low water-holding and fertility in golf course topsoil layers.

• Journal of Adhesion and Interface
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• v.21 no.3
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• pp.93-100
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• 2020

3D printing technology enables proper objects to be made through an additive manufacturing method, but resulting in dimension deviation of the product due to contraction phenomenon as cooling melted filament resin injected from high-temperature use environment. In this research, we studied on acrylic adhesives for 3D printer build sheet in order to fabricate high-quality products with a precise shape and to well-mount without distortion. The solvent-free UV-curable acrylic adhesive formulation was designed by adding 4-acryloylmorpholine (ACMO) with high adhesion, toughness, glass transition temperature so that adhesion properties are stable at high temperature and products are easily mounted/detached from the adhesives. The designed formulation was polymerized through two-steps using post-addition of monomers. Using this, the acrylic adhesive was coated to make a film and then analyzed using various experimental techniques. As a result, the fabricated adhesive exhibited high glass transition temperature and there was little gap in peel strength before and after thermal treatment. Moreover, it was confirmed by rheological analysis that this adhesive can provide great bonding/debonding ability without distortion. We demonstrated the fabrication of a rectangular product using a 3D printing method using our acrylic adhesive as a build sheet. Mounting ability and workability were satisfactory and dimension deviation of the product was tiny. Because the product is easily detachable from the acrylic adhesive developed here than conventional build sheets, it is expected that this will provide work convenience to users who use the 3D printer.

• Journal of Energy Engineering
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• v.18 no.2
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• pp.132-135
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• 2009

Development of biofuels like ethanol and biodiesel for commercial uses is a recent phenomenon. However, the growth of ethanol and biodiesel has been impressive during the period 2000-2007yr. Globally, production of biodiesel stands around 8.3 billion liters. Europe leads the world in biodiesel production with 80% share of the global biodiesel production total. Today biodiesel fuels have been in commercial use in many countries and recently the world-wide biodiesel market has experienced considerable growth, which is partly due to various tax concession programs and other financial incentives. In Korea, biodiesel has already been used for transportation fuel, but not used for power generation fuel yet. Korean government has a strategy for renewable energy propagation, especially the goal of power generation amount by renewable energy is 3% of total power production by 2012. This paper focuses on the estimation study for effect of using biodiesel as power generation fuel. The study also has the plan to replace the fuel of thermal power plant, gas turbine and distributed power generation system. As the increase of biodiesel fuel, I look forward to environment-friendly power generation and the strategy of Renewable Portfolio Standards(RPS).

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.3
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• pp.1033-1041
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• 2014

Rapid urbanization of Korea was an unprecedented example in the world and urban population increased significantly. As a result, unbalanced distribution of population is serious problem in Korea because approximately 50% of the population is concentrated in the capital area that is 10% of nation's territory, thereby occurring various urban problems including UHI. Hence, Sejong Special Autonomous City was inaugurated officially on 2 July 2012 in order to decentralize population of capital area and induce more balanced regional development. The Sejong City has been changed drastically over a period of years as developed practically since the late 2000's and is expected to have new problems of urbanization. The land cover change due to urbanization is the main cause of UHI that urban area is significantly warmer than its surrounding areas and UHI is not only affecting urban climate change but also natural environment. So the purpose of this research is to analyze level of urbanization and UHI effect and to provide the correlation analysis between Land Surface Temperature and spectral indices. To achieve this, satellite imagery from LANDSAT were used. NDVI, NDBI, and UI were calculated using red, near-infrared, mid-infrared ($0.63{\mu}m-1.75{\mu}m$) images and LST was retrieved utilizing thermal infrared ($10.4{\mu}m-12.5{\mu}m$) image. Based on each index and LST, Changes of NDVI, UI and UHI through TVI were analyzed in Sejong City. UHI effect increased around newly constructed multi-functional administrative city, the correlation between LST and NDVI was negative and UI was strong positive.

• Bulletin of the Korean Chemical Society
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• v.28 no.4
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• pp.581-588
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• 2007

To enhance the photodecomposition of concentrated ammonia into N2, Pt/V-TiO2 photocatalysts were prepared using solvothermal and impregnation methods. Nanometer-sized particles of 0.1, 0.5 and 1.0 mol% V-TiO2 were prepared solvothermally, and then impregnated with 1.0 wt% Pt. The X-ray diffraction (XRD) peaks assigned to V2O5 at 30.20 (010) and Pt metal at 39.80 (111) and 46.20 (200) were seen in the 1.0 wt% Pt/ 10.0 mol% V-TiO2. The particle size increased in the order: pure TiO2, V-TiO2 and Pt/V-TiO2 after thermal treatment at 500 °C, while their surface areas were in the reverse order. On X-ray photoelectron spectroscopy (XPS), the bands assigned to the Ti2p3/2 and Ti2p1/2 of Ti4+-O were seen in all the photocatalysts, and the binding energies increased in the order: TiO2 < Pt/V-TiO2 < V-TiO2. The XPS bands assigned to the V2p3/2 (517.85, 519.35, and 520.55 eV) and V2p1/2 (524.90 eV) in the V3+, V4+ and V5+ oxides appeared over V-TiO2, respectively, while the band shifted to a lower binding energy with Pt impregnation. The Pt components of Pt/ V-TiO2 were identified at 71.60, 73.80, 75.00 and 76.90 eV, which were assigned to metallic Pt 4f7/2, PtO 4f7/2, PtO2 4f7/2, and PtO 4f5/2, respectively. The UV-visible absorption band shifted closer towards the visible region of the spectrum in V-TiO2 than in pure TiO2 and; surprisingly, the Pt/V-TiO2 absorbed at all wavelengths from 200 to 800 nm. The addition of vanadium generated a new acid site in the framework of TiO2, and the medium acidic site increased with Pt impregnation. The NH3 decomposition increased with the amount of vanadium compared to pure TiO2, and was enhanced with Pt impregnation. NH3 decomposition of 100% was attained over 1.0 wt% Pt/1.0 mol% V-TiO2 after 80 min under illumination with 365 nm light, although about 10% of the ammonia was converted into undesirable NO2 and NO. Various intermediates, such as NO2, -NH2, -NH and NO, were also identified in the Fourier transform infrared (FT-IR) spectra. From the gas chromatography (GC), FT-IR and GC/mass spectroscopy (GC/MS) analyses, partially oxidized NO and NO2 were found to predominate over V-TiO2 and pure TiO2, respectively, while both molecules were reduced over Pt/V-TiO2.

• Journal of Advanced Marine Engineering and Technology
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• v.40 no.9
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• pp.762-767
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• 2016

High thermal efficiency and the ability to use various types of fuel are a few of the many advantages of diesel engines. However, a major disadvantage is that their exhaust emissions are more harmful to humans and the environment than that of conventional engine. Consequently, the provisions of the international emissions standards for diesel engine equipped passenger cars, commercial vehicles, and ships have become more stringent. These standards include the EU Euro 6, the IMO MEPC Tier 3, and the US EPA Tier 4. Ryu et al. published a study that applied fuel additives to two-stroke diesel engines. In this study, a four-stroke diesel engine using diesel oil for a generator is utilized as the test subject, and an experiment is performed to verify whether fuel additive can be used to improve performance and exhaust emissions. In addition, this experimental study presents research results for the application of fuel additives in both two-stroke and four-stroke diesel engines. The experimental results were compared and analyzed by placing an oil-soluble calcium-based organometallic compound in diesel oil. The results confirmed that the addition of fuel additive improved the performance (fuel consumption rate, exhaust gas temperature) and exhaust emissions (NOx, CO) of the diesel engine.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.22 no.7
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• pp.1021-1029
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• 2018

The marine buoys are operated in various domains, which are navigation route and danger maker, weather and environment monitoring, military strategical element, etc. If the marine buoy is damaged, there consumes many cost and time for recovery or replacement, because of severe environmental condition, and causes a risk possibility of secondary accident. In this paper, we developed an active monitoring and approach alarm providing system using trail cameras and AIS for protection for the marine buoys. To do this, we analyzed existing researches and similar systems, extracted requirements for enhancement, and designed the system architecture that applied the enhanced elements. The main considerations of system enhancement are: integration of AIS and trail cameras, adopting of phased alarm technique by approaching ships, applying of selective communication module, conducting the image processing of ships for providing alarm, and applying thermal cameras. After that, we developed the system using designed architecture and verified effectiveness of the system based on laboratory or field-level tests.

• Journal of Science and Technology Studies
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• v.19 no.3
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• pp.119-166
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• 2019

The risk of electromagnetic field(EMF) from power lines has been heavily disputed whenever high-voltage power line towers were built in South Korea. Local communities and civic groups had regarded burying the lines in the ground as an alternative to building power line towers. In 2014, however, when an elementary school science teacher reported the results of EMF measurements over the underground power lines to the Asian Citizens' Center for Environment and Health (ACCEH), the risk controversy over underground power lines took a whole new turn. The level of EMF from underground power lines turned out to be higher, and therefore more harmful than that from power line towers. In the debates that took place from then on over the EMF risk, ACCEH and NIER(National Institute of Environmental Research) presented conflicting topographies of EMF risk. This paper examines measuring practices of ACCEH and NIER by analyzing the measuring sites, measuring devices, and measuring heights chosen by each organization. This paper further examines how ACCEH and NIER mobilized various standards(EMF exposure limit, measurement guideline, categorization of carcinogens) differently. This controversy on the EMF from underground power lines of Seoul has raised concerns on the non-thermal effects of EMF in the long-term exposure and has led people to question whether burying the power lines is the safe alternative to building power line towers. Furthermore, this suggests conflicting answers on whether Seoul, where 90 % of transmission lines were already buried, is a safely managed place or not.