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( Dongwoo Kang ),( Jinwon Park ) 한국폐기물자원순환학회(구 한국폐기물학회) 2019 ISSE 초록집 Vol.2019 No.-
In order to minimize the impact caused by global warming, the efforts to reduce the amount of carbon dioxide emission have been made for decades. There are various technologies in carbon reduction fields and usually they are called CCUS (Carbon Capture Utilization and Storage). In the CCUS technologies, carbon dioxide produced from various sources including power plants, industrial process are separated and processed. In CCS method, carbon dioxide is separated followed by compression and storage in the deep ocean or underground. However, to regenerate the absorbents, especially in wet absorption method, heat is essentially required to heat up the absorbents. To reduce this energy requirement problems and to enhance the economic feasibility of the whole process, the concept to make carbon dioxide into the reusable one has come arise. One of the most studied one is to make carbon dioxide into the metal carbonates by combining them with metal ions. However, securing metal cations are one of the problems. Some obtained its sources from natural minerals such as limestone. However, it seems not adequate to use resources to treat carbon dioxide, hence, we tried to use reject brine which have been produced from refined salt production facilities. In this process, natural seawater is drawn and sodium chloride is separated to make commercial salt product. And remaining solution is heated up to separate remaining salts. As a result, final solution becomes super-concentrated due to the evaporation of the solvent. When this reject brine is directly released to the near shore, it can trigger partial changes in concentration of near-ocean resulting in the negative impact in ecosystem. If divalent metal cations such as calcium or magnesium ions can be obtained in this reject brine solution, both securing sources and preventing environmental impact can be achieved at the same time. Herein, we developed a new carbon utilization method using calcium and magnesium cations dissolved in seawater-based industrial wastewater. Calcium and magnesium were separated in the form of hydroxide precipitate. Using 30 wt% aqueous monoethanolamine (MEA) solution, carbon dioxide was captured and reacted with the hydroxides to produce calcium carbonate and magnesium carbonate. After Ca<sup>2+</sup> and Mg<sup>2+</sup> separation, sodium chloride was used to produce sodium bicarbonate. The entire process produced 0.3819, 0.2549 and 0.4579 mol of calcium carbonate, magnesium carbonate and sodium bicarbonate, respectively. X-ray diffraction (XRD) and scanning electron microscopy (SEM) were conducted to investigate their crystal structure. Moreover, FT-IR spectroscopy was utilized to investigate the ionic species under Na<sup>+</sup>-rich conditions.
Full Color Stop Bands in Hybrid Organic/Inorganic Block Copolymer Photonic Gels by Swelling−Freezing
Kang, Changjoon,Kim, Eunjoo,Baek, Heeyoel,Hwang, Kyosung,Kwak, Dongwoo,Kang, Youngjong,Thomas, Edwin L. American Chemical Society 2009 JOURNAL OF THE AMERICAN CHEMICAL SOCIETY - Vol.131 No.22
<P>We report a facile way of fabricating hybrid organic/inorganic photonic gels by selective swelling and subsequent infiltration of SiO(2) into one type of lamellar microdomain previously self-assembled from modest-molecular-weight block copolymers. Transparent, in-plane lamellar films were first prepared by assembly of polystyrene-block-poly(2-vinylpyridine) (PS-b-P2VP), and subsequently the P2VP domains were swollen with a selective solvent, methanol. The swollen structures were then fixated by synthesizing SiO(2) nanoparticles within P2VP domains. The resulting frozen photonic gels (f-photonic gels) exhibited strong reflective colors with stop bands across the visible region of wavelengths.</P>
Carbon Dioxide Capture and High Purity Calcium Carbonate Production by Target Metal Separation
Dongwoo Kang,Min-Gu Lee,Yunsung Yoo,Jinwon Park 한국폐기물자원순환학회 2017 한국폐기물자원순환학회 학술대회 Vol.2017 No.11
In this research, carbon dioxide is captured and chemically converted to high purity calcium carbonate salt which can be used for various industrial fields. Aqueous indirect inorganic carbonation methods were applied throughout the research and seawater-based industrial wastewater was utilized for metal ion supply. For CO2 capture, representative alkanolamine absorbent solutions in 30 wt% concentration were used, that is, monoethanolamine (MEA), diethanolamine (DEA), and methyldiethanolamine (MDEA). For high purity metal ion separation, calcium ion contained in the seawater-based industrial waster was separated in the form of gypsum followed by the carbonation reaction to form high purity calcium carbonate salt. Consiering the final products and their economic cost, the cycle using MEA will be proper. However, if MDEA can be used, the amount of carbon dioxide capture capacity per cycle would be great. Also, conceptual continuous cycle which produces calcium carbonate and magnesium carbonate was suggested. This research may help the nations such as European nations or east asian countries like Korea and Japan where no adequate CO2 storages exist and crust activities are in progress, if commercialized.
Carbon Dioxide Utilization using Industrial Wastewater Produced from Refined Salt Production Process
( Dongwoo Kang ),( Min-gu Lee ),( Hoyong Jo ),( Eunjung Kim ),( Jinwon Park ) 한국폐기물자원순환학회(구 한국폐기물학회) 2015 한국폐기물자원순환학회 3RINCs초록집 Vol.2015 No.-
In order to prevent climate changes caused by greenhouse gas emissions, researchers in many nations are struggle to reduce the amount of greenhouse gases contained in industrial flue gas. Among various greenhouse gases, carbon dioxide gas occupies large portion. So researches concerned with carbon dioxide reduction got many attentions. In this research, carbon capture and utilization and detailed methodology is dealt. Wastewater produced from refined salt production process was used as reactant in order to produce precipitated calcium carbonate salt which can be used as construction materials, additive in engineering plastic, pharmaceutical substances and so on.
Efficient and Secure Biometric-Based User Authenticated Key Agreement Scheme with Anonymity
Kang, Dongwoo,Jung, Jaewook,Kim, Hyoungshick,Lee, Youngsook,Won, Dongho Hindawi Limited 2018 Security and communication networks Vol.2018 No.-
<P>At present, a number of users employ an authentication protocol so as to enjoy protected electronic transactions in wireless networks. In order to establish an efficient and robust the transaction system, numerous researches have been conducted relating to authentication protocols. Recently, Kaul and Awasthi presented an user authentication and key agreement scheme, arguing that their scheme is able to resist various types of attacks and preserve diverse security properties. However, this scheme possesses critical vulnerabilities. First, the scheme cannot prevent two kinds of attacks, including off-line password guessing attacks and user impersonation attacks. Second, user anonymity rule cannot be upheld. Third, session key can be compromised by an attacker. Fourth, there is high possibility that the time synchronization trouble occurs. Therefore, we suggest an upgraded version of the user authenticated key agreement method that provides enhanced security. Our security and performance analysis shows that compared, to other associated protocols, our method not only improves the security level but also ensures efficiency.</P>
( Dongwoo Kang ),( Yunsung Yoo ),( Injun Kim ),( Jinwon Park ) 한국폐기물자원순환학회(구 한국폐기물학회) 2018 한국폐기물자원순환학회 심포지움 Vol.2018 No.1
In order to prevent climate changes which were thought to be caused by the excessive greenhouse effect triggered by the greenhouse gases (GHGs) in atmosphere, lots of GHGs reduction technologies were developed and applied. Among six representative GHGs, carbon dioxide occupies the most highest portion higher than 90% for recent years. Although the global warming potential of it is lowest, its level of contribution towards global warming seems highest considering its amount of emission. After carbon dioxide is captured from emission points such as caol-fired power plants, it is separated and transported to storage site, followed by injection into deep underground cavities. However, some nations are not thought to be proper for this geological storage and there are possibilities of leakage by crust activities. Considering these drawbacks, carbon dioxide was converted to metal carbonate with high purity by the reaction between the metal ion contained in the seawater-based wastewater and captured carbon dioxide. In order to achieve high purity for the utilization of the product, calcium cation contained in the seawater was separated in the form of calcium sulfate dihydrate. After that, it was converted to calcium carbonate precipitate by the ionic carbon dioxide. For the absorbent, monoethanolamine, diethanolamine and methyl-diethanolamine were used. In order to investigate the characteristics of the products, X-Ray Diffraction analysis were performed and Scanning Electron Microscope images were obtained.