• Bulletin of the Korean Chemical Society
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• v.33 no.7
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• pp.2149-2155
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• 2012

A metal-free and efficient procedure for the oxidation of alcohols into the corresponding carbonyl compounds has been described using ammonium nitrate in the presence of silica sulfuric acid under mild and heterogeneous conditions. The use of non-toxic and inexpensive materials, simple and clean work-up, short reaction times and good yields of the products are among the advantages of this method.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2013.11a
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• pp.228-229
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• 2013

As the rapid and various changing of social aspects, the structures are getting bigger, higher and more complex. This study is research trend of fire safety in high-rise buildings to Asia country. Research Trend for the Fire Safety to present the plan to clean up the problems and ways to improve future domestic.

• Journal of the Korean Mathematical Society
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• v.61 no.2
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• pp.357-375
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• 2024

The smooth quintic del Pezzo variety Y is well-known to be obtained as a linear sections of the Grassmannian variety Gr(2, 5) under the Plücker embedding into ℙ⁹. Through a local computation, we show the Hilbert scheme of conics in Y for dimY ≥ 3 can be obtained from a certain Grassmannian bundle by a single blowing-up/down transformation.

• Clean Technology
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• v.10 no.1
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• pp.19-25
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• 2004

The leather was fixed with various colors through the dyeing process in leather manufacturing. During the dyeing process, the amount of 30~50% dyestuff which were not bonded with leather drained with waste water. These dyestuff raise lots of environmental problems, so technology for improving the fixing effect, levelling effect and penentration effect with the use of small amount of dyestuff has been required. Also, insufficient color fastness level 2~3 grade for common natural leather needs to be improved at the same time. Accordingly, the use of ultrasound(us) in dyeing process has decreased the amount of dyestuff and obtained the smooth permeability effect. So, we could find that the reduction of amount of dyestuff in wastewater led to decrease in environmental trouble caused by leather waste water with severe contamination degree and improved fastness up to 0.5 grades.

• Corrosion Science and Technology
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• v.14 no.1
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• pp.12-18
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• 2015

Since the operation period of nuclear power plants has increased, the degradation of buried pipes gradually increases and recently it seems to be one of the emerging issues. Maintenance on buried pipes needs high quality of management system because outer surface of buried pipe contacts the various soils but inner surface reacts with various electrolytes of fluid. In the USA, USNRC and EPRI have tried to manage the degradation of buried pipes. However, there is little knowledge about the inspection procedure, test and manage program in the domestic nuclear power plants. This paper focuses on the development and build-up of real-time monitoring and control system of buried pipes. Pipes to be tested are tape-coated carbon steel pipe for primary component cooling water system, asphalt-coated cast iron pipe for fire protection system, and pre-stressed concrete cylinder pipe for sea water cooling system. A control system for cathodic protection was installed on each test pipe which has been monitored and controlled. For the calculation of protection range and optimization, computer simulation was performed using COMSOL Multiphysics (Altsoft co.).

• Clean Technology
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• v.2 no.1
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• pp.69-79
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• 1996

Sulfur emission control in coal gasification plants implies the removal of $H_2S$ from the fuel gas in the gas clean-up system. In this study, the effects of particle size of sorbents, temperature of sulfidation and sorbent characteristics on the $H_2S$ removal efficiency of manganese ore were investigated. Experimental results showed that the removal efficiency of $H_2S$ was optimum when the temperature was about $700^{\circ}C$. And that the smaller particle size, the higher the $H_2S$ removal efficiency, but that was not effective very much. As the temperature increases, the reactivity of sorbents has lowered because agglomeration of sorbents increased the intraparticle transport resistance. This phenomenon was confirmed by SEM photographs. The equilibrium ratio ($P_{H_2O}/P_{H_2S}$) obtained by experiments is represented as a ${\log}(P_{H_2O}/P_{H_2S})=5653/T-3.7909$. It was showed that the natural manganese ore could be used as a sorbent because its capacity for $H_2S$ removal is equivalent to the eariler developed sorbents.

• Clean Technology
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• v.13 no.2
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• pp.104-108
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• 2007

Biodiesel is a fatty acid alkyl ester produced by chemical reaction of a vegetable oil or animal fat and an alcohol. It is getting attention as a clean alternative energy that can replace gas oils. In this study, strong acidic ion exchange resin was introduced in the pretreatment process of the used cooking oil and rapeseed oil to enhance the conversion of the oil to the biodiesel by removing FFA(free fatty acid). More than 90% FFA was removed. Dry resins showed higher FFA removal efficiency than wet resins. Using transesterification the conversion of triglyceride into fatty acid methyl ester was raised up to 98%. These results can be applicable to the pretreatment of biodiesel feedstocks having high acidic value.

• Clean Technology
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• v.15 no.1
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• pp.1-8
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• 2009

The adoption of compressed natural gas (CNG) as a vehicle fuel is a common phenomenon as it is accelerating worldwide. Increasing number of CNG driven vehicles around the world has jumped up from one million in 1996 to five million in 2006. CNG as a vehicle fuel is very popular to the end users because of its clean-burning properties and cost effective solution compared to other alternative fuels like diesel and gasoline. The use of CNG as a fuel reduces vehicular emission that is consisted of carbon monoxide (CO), hydrocarbons (HC), oxides of nitrogen ($NO_x$), carbon dioxide ($CO_2$) etc. This research highlights the characteristics of CNG vehicles, CNG arrangement in the vehicles, CNG fueling procedures and most importantly the environmental and economic factors that are highly considered as cost effective solution for the flexibility of using CNG in the automobiles.

• Restorative Dentistry and Endodontics
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• v.47 no.1
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• pp.13.1-13.13
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• 2022

Objectives: This study evaluated the efficacy of 3 reciprocating systems and the effects of 2 instruments for irrigant activation on filling material removal. Materials and Methods: Forty mesiobuccal roots of maxillary molars were prepared up to size 25.06 and obturated. Micro-computed tomography (micro-CT) examination #1 was performed. Teeth were then divided into 4 groups (n = 10), according to the retreatment protocol: (1) manual, (2) Reciproc Blue, (3) WaveOne Gold, and (4) X1 Blue. Micro-CT examinations #2 and #3 were performed after filling removal and repreparation, respectively. Next, all teeth were divided into 2 new groups (n = 20) according to the irrigant activation protocol: XP Clean (XP Clean size 25.02) and Flatsonic (Flatsonic ultrasonic tip). Micro-CT examination #4 was performed after irrigant activation. Statistical analysis was performed with a significance level set at 5%. Results: WaveOne Gold removed a significantly greater amount of filling material than the manual group (p < 0.05). The time to reach the WL was similar for all reciprocating systems (p > 0.05). X1 Blue was faster than the manual group (p < 0.05). Only manual group improved the filling material removal after the repreparation stage (p < 0.05). Both activation protocols significantly improved the filling material removal (p < 0.05), without differences between them (p > 0.05). Conclusions: None of the tested instruments completely removed the filling material. X1 Blue size 25.06 reached the working length in the shortest time. XP Clean and Flatsonic improved the filling material removal.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.36 no.5
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• pp.469-473
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• 2003

Transplantation of Sargassum horneri to natural substrate using the rope seeding method was undertaken. Seeding of S. horneri was grown on net in an indoor tank up to 0.2-0.3 cm in frond length for 2 months, and then transplanted to an architecture tile $(10\times10\;cm)$ with underwater glue and an iron pipe. After two months, number of S. horneri on the tile decreased because of grazing by herbivores. However, S. horneri on the iron pipe grew up to 0.5-2.0 cm in frond length. After 7 months, they rapidly grew up to a frond length of 11.0-203.0 cm with a mean frond length of 122.6 cm. S. horneri grew up to a maximum frond length of 313.0 cm, and mean frond length of 228.0 cm, after 10 months. The artificial S. hornevi beds can be used to clean the seawater and also be utilized as a source of marine biomass as well as for supplying habitat, shelter and spawning beds for fish and invertebrates.