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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.
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>
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.
Oxidation resistance of iron and copper foils coated with reduced graphene oxide multilayers.
Kang, Dongwoo,Kwon, Jee Youn,Cho, Hyun,Sim, Jae-Hyoung,Hwang, Hyun Sick,Kim, Chul Su,Kim, Yong Jung,Ruoff, Rodney S,Shin, Hyeon Suk American Chemical Society 2012 ACS NANO Vol.6 No.9
<P>Protecting the surface of metals such as Fe and Cu from oxidizing is of great importance due to their widespread use. Here, oxidation resistance of Fe and Cu foils was achieved by coating them with reduced graphene oxide (rG-O) sheets. The rG-O-coated Fe and Cu foils were prepared by transferring rG-O multilayers from a SiO(2) substrate onto them. The oxidation resistance of these rG-O-coated metal foils was investigated by Raman spectroscopy, optical microscopy, and scanning electron microscopy after heat treatment at 200 °C in air for 2 h. The bare metal surfaces were severely oxidized, but the rG-O-coated metal surfaces were protected from oxidation. This simple solution process using rG-O is one advantage of the present study.</P>