Development of PCM Color Coated Steel Sheets with Excellent Antiviral and Antimicrobial Properties

( Du-hwan Jo ),( Seongil Kim ),( Jinkyun Roh ),( Doojin Paik ),( Myungsoo Kim ) 한국부식방식학회 2024 Corrosion Science and Technology Vol.23 No.2

Recently, due to the rapid spread and continuation of COVID-19, customer demand for health and hygiene has increased, requiring the development of new products that express antiviral and antibacterial properties. In particular, viruses are much smaller in size than bacteria and have a fast propagation speed, making it difficult to kill. POSCO has developed eco-friendly PCM color coated steel sheets with excellent antiviral properties by introducing inorganic composite materials to the color coating layer on the surface of Zn-Al-Mg alloy plated steels. The virus is not only destroyed by adsorption of metal ions released from the surface of the coating film, but is also further promoted by the generation of reactive oxygen species by the reaction of metal ions and moisture. As a result of evaluating the developed products under the International Standard Evaluation Act, the microbicidal activity was 99.9% for viruses, and 99.99% for bacteria and 0% fungi. In particular, excellent results were also shown in the durability evaluation for life cycle of the product. The developed product was applied as a wall of school classrooms and toilets and ducts for building air conditioning, resulting in excellent results. Developed products are being applied for construction and home appliances to practice POSCO's corporate citizenship.

Development of High Functional Black Resin Coated Electrogalvanized Steel Sheet for Digital TV Panel

( Du Hwan Jo ),( Moon Jae Kwon ),( Jae Hva Lee ),( Hee Seung Kang ),( Yongn Gvun Jung ),( Von Kvun Song ),( Min Hwan Jung ),( Soon Hvoun Cho ),( Veong Bong Cho ),( Myoung Rae Cho ),( Byoung Chon Cho ) 한국부식방식학회(구 한국부식학회) 2013 Corrosion Science and Technology Vol.12 No.1

Recently Digital TV industry has drastically been moving the illuminating system, which causes an obvious product change from PDP and LCD to LED model to provide high-definition image. Due to strong competition in the digital industry. TV manufacturers make a great efforts to reduce production cost by using low-priced materials such as steels instead of aluminum and plastic etc. In this paper we have developed a new low-priced electrogalvanized steel sheet, which has a black resin composite layer, to substitute conventional high-priced PCM steel and plastic mold for rear cover panel in the digital TV. The black resin composite was prepared by mechanical dispersion of the mixture solution that consists of high solid polyester resin, melamine hardener, black pigment, micronized silica paste, polyacrylate texturing particle and miscellaneous additives. The composite solution was coated on the steel sheet using roll coater followed by induction furnace curing and cooling. Although the coated layer has a half thickness compared to the conventional PCM steels having 23tn thickness, it exhibits excellent quality for the usage of rear cover panel. The new steel sheet was applied to test products to get quality certification from worldwide electronic appliance customers. Detailed discussion provides in this paper including preparation of composite solution, roll coating technology, induction curing technology and quality evaluation from customers.

Improved Corrosion and Abrasion Resistance of Organic-Inorganic Composite Coated Electro-galvanized Steels for Digital TV Panels

( Du Hwan Jo ),( Sang Geol Noh ),( Jong Tae Park ),( Choon Ho Kang ) 한국부식방식학회(구 한국부식학회) 2015 Corrosion Science and Technology Vol.14 No.5

Recently, household electronic industries require environmentally-friendly and highly functional steels in order to enhance the quality of human life. Customers especially require both excellent corrosion and abrasion resistant anti-fingerprint steels for digital TV panels. Thus POSCO has developed new functional electro-galvanized steels, which have double coated layers with organic-inorganic composites on the zinc surface of the steel for usage as the bottom chassis panel of TVs. The inorganic solution for the bottom layer consists of inorganic phosphate, magnesium, and zirconium compounds with a small amount of epoxy binder, and affords both improved adhesion properties by chemical conversion reactions and corrosion resistance due to a self-healing effect. The composite solution for the top layer was prepared by fine dispersion of organic-inorganic ingredients that consist of a urethane modified polyacrylate polymer, hardener, silica sol and a titanium complex inhibitor in aqueous media. Both composite solutions were coated on the steel surface by using a roll coater and then cured through an induction furnace in the electro-galvanizing line.New anti-fingerprint steel was evaluated for quality performance through such procedures as the salt spray test for corrosion resistance, tribological test for abrasion resistance, and conductivity test for surface electric conductance regarding to both types of polymer resin and coating weight of composite solution. New composite coated anti-fingerprint steels afford both better corrosion resistance and abrasion properties compared to conventional anti-fingerprint steel that mainly consists of acrylate polymers. Detailed discussions of both composite solutions and experimental results suggest that urethane modifications of acrylate polymers of composite solutions play a key role in enhanced quality performances.

Chromate-free Hybrid Coating for Corrosion Protection of Electrogalvanized Steel Sheets

( Du Hwan Jo ),( Moon Jae Kwon ),( Jong Sang Kim ) 한국부식방식학회(구 한국부식학회) 2012 Corrosion Science and Technology Vol.11 No.1

Both electrogalvanized and hot-dip galvanized steel sheets have been finally produced via organic-inorganic surface coating process on the zinc surface to enhance corrosion resistance and afford additional functional properties. Recently, POSCO has been developed a variety of chromate-free coated steels that are widely used in household, construction and automotive applications. New organic-inorganic hybrid coating solutions as chromate alternatives are comprised of surface modified silicate with silane coupling agent and inorganic corrosion inhibitors as an aqueous formulation. In this paper we have prepared new type of hybrid coatings and evaluated quality performances such as corrosion resistance, spot weldability, thermal tolerance, and paint adhesion property etc. The electrogalvanized steels with these coating solutions exhibit good anti-corrosion property compared to those of chromate coated steels. Detailed components composition of coating solutions and experimental results suggest that strong binding between organic-inorganic hybrid coating layer and zinc surface plays a key role in the advanced quality performances.

Excellent Seam Weldable Nano-Composite Coated Zn-Ni Plating Steels for Automotive Fuel Tank

( Du-hwan Jo ),( Sang-man Yun ),( Kee-cheol Park ),( Myung-soo Kim ),( Jong-sang Kim ) 한국부식방식학회(구 한국부식학회) 2019 Corrosion Science and Technology Vol.18 No.1

Steels for automotive fuel tank require unique properties such as corrosion resistance for fuel, welding for joining, forming for press, and painting for exterior. Recently, automakers have been requiring excellent seam weldable steels to enhance manufacturing productivity of fuel tank. Thus, POSCO developed a new type of functional steels coated with nano-composite thin layer on Zn-Ni plating steels. The nano-composite coating solution was prepared by mechanical fine dispersion of solutions consisting of polymeric resin and nano-composite materials in aqueous media. The composite solution was coated on the plating steel surface by using roll coater and cured through induction furnace. These new developed plating steels were evaluated for quality performances such as seam and spot weldability, press formability, and corrosion resistance. These new functional steels coated with nano-composite layer exhibited excellent seam weldability and press formability. Detailed discussion of coating solution and experimental results suggest that nano-sized composite dispersion as coating layer plays a key role in enhancing the quality performance.

Corrosion Resistance of Mg-Added Galvannealed Steel Sheets with Nano-Composite Coating

( Du-hwan Jo ),( Sang-man Yun ),( Doo-jin Paik ),( Myung-soo Kim ),( Moon-hi Hong ) 한국부식방식학회(구 한국부식학회) 2020 Corrosion Science and Technology Vol.19 No.2

As competition among global automakers intensifies, demand for materials that are better in price and performance is increasing. While steel and plastic materials compete for automotive fuel tanks, plastic materials have advantages such as light weight for automobiles. However, they have high prices. Accordingly, in this paper, four types of Zn-X plated steel sheets, electroplating (X = none, Sn) and galvannealed (X = Fe, Fe-Mg), were manufactured and their applicability as a fuel tank material was evaluated. Nano-composite coating solution with good conductivity was treated on the surface of plated steels using a roll coater and then cured through induction furnace to improve corrosion resistance. Quality characteristics such as corrosion resistance, fuel resistance to diverse gasoline and diesel fuels, and seam weldability were evaluated for the above plated steels. Their properties were compared and analyzed with conventional Zn-Ni electroplating steels. Among the above plated steels, Zn-Fe-Mg galvannealed steels coated with nano-composite coating exhibited better properties than other steels. Detailed experimental results suggest that evenly distributed Mg elements on the coating layer play a key role in the enhanced quality performance.

The Biological Functionality of Electro-Galvanized Steels Coated with a Hybrid Composite Containing Pyrethroid

( Du-hwan Jo ),( Myung-soo Kim ),( Jong-sang Kim ),( Hyun-woo Oh ) 한국부식방식학회(구 한국부식학회) 2018 Corrosion Science and Technology Vol.17 No.2

The electronic industries require environmentally-friendly and highly functional materials to enhance the quality of human life. Home appliances require insect repellent steels that work to protect household microwave ovens from incurring damage by insects such as fire ants and cockroaches in tropical regions. Thus, POSCO has developed new types of functional steels, coated with an array of organic-inorganic hybrid composites on the steel surface, to cover panels in microwave ovens and refrigerators. The composite solution uses a fine dispersion of hybrid solution with polymeric resin, inorganic and a pyrethroid additive in aqueous media. The hybrid composite solution coats the steel surface, by using a roll coater and is cured using an induction curing furnace on both the continuous galvanizing line and the electro-galvanizing line. The new steels were evaluated for quality performances, salt spray test for corrosion resistance and biological performance for both insect repellent and antimicrobial activity. The new steels with organic-inorganic composite coating exhibit extraordinarily biological functionalities, for both insect repellent and antimicrobial activities for short and long term tests. The composite-coating solution and experimental results are discussed and suggest that the molecular level dispersion of insecticide on the coating layer is key to biological functional performances.

Syntheses and Reactivites with Olefins of Ruthenium(IV) Oxo/Ruthenium(II)-Aqua Complexes that Contain 2,6-Bis(N-pyrazolylpyridine)

Jo, Du-Hwan,Yeo, Hwan-Jin Korean Chemical Society 1993 Bulletin of the Korean Chemical Society Vol.14 No.6

The syntheses and reactivities with olefins of $[Ru^{II}(L_3)(L_2)OH_2]^{2+}$ $[L_3$= 2,6-bis(N-pyrazolyl)pyridine(bpp), 2,6-bis(3,5-dimethyl-N-pyrazolyl)pyridine $(Me_4bpp);\;L_2$= 2,2'-bipyridine(bpy), 4,4'-dimethyl-2,2'-bipyridine $(Me_2bpy)$] are described. Their spectral and redox properties in aqueous solution were investigated. Evidence for each one electron redox process for the $Ru^{IV}-Ru^{III}$ and $Ru^{III}-Ru^{II}$ couples has been obtained. Oxidation of $[Ru^{II}(bpp)(bpy)OH_2]^{2+}$ with $Ce^{IV}$ gave $[Ru^{IV}(bpp)(bpy)O]^{2+}$. The $[Ru^{IV}$= 0 complex is paramagnetic $({\mu}_{eff}=2.82)$ and the complexes $[Ru(L_3)(L_2)OH_2]^{2+}$ are robust catalysts for the oxidation of styrene, cyclohexene, and cyclooctene with cooxidant such as NaOCl. Product distributions and selectivities are discussed by varying the number of the substituted-methyl group in the ring.

Drone for building fire suppression

( Jo Yong Du ),( Lim Jong Wook ),( Oh Ju Hwan ),( Kang Min Gyu ),( Go Han Il ),( Seung Nam Min ) 한국감성과학회 2019 한국감성과학회 국제학술대회(ICES) Vol.2019 No.-

introduction: Most of the developed cities are now highly populated with increased high-rise buildings. In general, high-rise structures are not preferred due to user perception of insecurity in case of fire and high cost of the building. Recently, there were fire accident occurred in an eight-story building that resulted in numerous causalities and property damage. Globally, there is a constant increase in fire accident in high-rise building. Based on the National Security Agency, the total number of fires in the apartment was 5,798. In that, the high-rise building fire accounted about 60.4% of all building fires. However, not much effort taken to reduce the rate of fire accidents especially in high-rise building. Purpose: The purpose of this study is to conduct a basic research on how to reduce a fire at an early stage by placing a fire extinguisher in the drones. It also aims at increasing the speed of fire fighters responses to reduce causalities and property damage. Method: First, this study adopted a method of launching a hand grenade type throwing fire extinguisher into a drone. We selected DJI Inspire 1 model with wide range of manoeuvrability, less affected by wind, and can withstand weight of the hand grenade type fire extinguisher (1.2 kg) also. In addition, we surveyed drone specialists and fire-fighters to determine the appropriate number of fire extinguishers and their location. Conclusion/Discussion: The survey concludes that a total of four hand grenade type throwing fire extinguisher could be installed in a drone and also the drone can throw the fire extinguisher at an angle of 100 degrees downward. However, the drones can fly about 15 minutes only. This survey also suggest that the fire drone would help to reduce fires in high-rise building and also it can reach fire sites six times faster than golden time. It is expected that about 2,000 ~ 3,000 drones to be placed in fire sites annually, particularly in high-rise building to reduce losses of both life and property

항콕시디엄지수에 의한 Polyether Ionophorous Antibiotics의 효능평가

조영웅,장두환 한국수의공중보건학회 1987 예방수의학회지 Vol.11 No.1