Magnetic mesoporous materials for removal of environmental wastes

Kim, Byoung Chan,Lee, Jinwoo,Um, Wooyong,Kim, Jaeyun,Joo, Jin,Lee, Jin Hyung,Kwak, Ja Hun,Kim, Jae Hyun,Lee, Changha,Lee, Hongshin,Addleman, R. Shane,Hyeon, Taeghwan,Gu, Man Bock,Kim, Jungbae Elsevier 2011 Journal of hazardous materials Vol.192 No.3

<P><B>Highlights</B></P><P>• Iron oxide particle embedded mesoporous silica and carbon are synthesized. • Both mesoporous materials are separated easily under aqueous condition using magnet. • Mercury or fluorescein is removed by using magnetic mesoporous material. • Tyrosinase is immobilized in magnetic mesoporous silica and reused after reaction. • Magnetic mesoporous materials are applicable to removal of environmental wastes.</P> <P><B>Abstract</B></P><P>We have synthesized two different magnetic mesoporous materials that can be easily separated from aqueous solutions by applying a magnetic field. Synthesized magnetic mesoporous materials, Mag-SBA-15 (magnetic ordered mesoporous silica) and Mag-OMC (magnetic ordered mesoporous carbon), have a high loading capacity of contaminants due to high surface area of the supports and high magnetic activity due to the embedded iron oxide particles. Application of surface-modified Mag-SBA-15 was investigated for the collection of mercury from water. The mercury adsorption using Mag-SBA-15 was rapid during the initial contact time and reached a steady-state condition, with an uptake of approximately 97% after 7h. Application of Mag-OMC for collection of organics from water, using fluorescein as an easily trackable model analyte, was explored. The fluorescein was absorbed into Mag-OMC within minutes and the fluorescent intensity of solution was completely disappeared after an hour. In another application, Mag-SBA-15 was used as a host of tyrosinase, and employed as recyclable catalytic scaffolds for tyrosinase-catalyzed biodegradation of catechol. Crosslinked tyrosinase in Mag-SBA-15, prepared in a two step process of tyrosinase adsorption and crosslinking, was stable enough for catechol degradation with no serious loss of enzyme activity. Considering these results of cleaning up water from toxic inorganic and organic contaminants, magnetic mesoporous materials have a great potential to be employed for the removal of environmental contaminants and potentially for the application in large-scale wastewater treatment plants.</P>

배터리 팩의 전기적 등가회로 모델 설계에 따른 SOC 추정성능 분석

김승우(Seungwoo Kim),김우용(Wooyong Kim),김성환(Sungwhan Kim),김종훈(Jonghoon Kim) 전력전자학회 2020 전력전자학술대회 논문집 Vol.2020 No.11

Analysis of directional neighbour discovery process in millimetre wave wireless personal area networks

Kim, Meejoung,Kim, Yong, Sang,Lee, Wooyong Institution of Engineering Technology 2013 IET networks Vol.2 No.2

<P>The millimetre wave (mmWave) band offers the potential for multi-gigabit indoor wireless personal area networks (WPANs). However, it has problems such as a short wavelength. To compensate, utilisation of directional antennas at the physical layer is recommended. For communications using this band, neighbour discovery using directional antennas (D-ND) is one of the crucial steps. In this study, the D-ND process is analysed mathematically for mmWave WPANs based on the concept of an exclusive region, and the values that are derived from the effect of using directional antennas. Maximising the neighbour discovery probability for a given amount of time is considered as an objective function. Performance measures are derived in closed forms, such as the probability of discovering a device for one self-advertising packet and the power-efficient sojourn time of a device in one direction. Numerical results are obtained using parameters based on the IEEE 802.15.3c standard. The results show that the efficiency of the D-ND depends not only on how often devices transmit a self-advertising packet, but also on antenna properties such as beamwidth. The mathematical analysis provides a theoretical basis for the D-ND process, and the obtained results illustrate the physical layer impact on neighbour discovery.</P>

A Current Sensor Fault-detecting Method for Onboard Battery Management Systems of Electric Vehicles Based on Disturbance Observer and Normalized Residuals

Wooyong Kim,Kunwoo Na,Kyunghwan Choi 제어·로봇·시스템학회 2023 International Journal of Control, Automation, and Vol.21 No.11

This study presents a current sensor fault-detecting method for an electric vehicle battery management system. The proposed current sensor fault detector comprises the nonlinear battery cell model, the Luenbergertype state estimator, and a disturbance observer-based current residual generator. The features of this study are summarized as follows: 1) A nonlinear state space representation of the battery cell model is derived so that the disturbance observer considering the engaged current as an external disturbance can be applied, 2) a nonlinear model-based state observer and disturbance observer are combined to deal with the state of charge estimation as well as the unknown current estimation and 3) the concept of the normalized residual is introduced for current sensor fault detection criteria. Because the proposed method can estimate the engaged current whether the current measurement is available or not, the residual between the estimated current and measured current can capture the current sensor fault. Additionally, the normalization process ensures the current sensor fault diagnosis can be realized regardless of the magnitude of the engaged current. The performance of the proposed current sensor fault algorithm was experimentally verified under several magnitudes of engaged current scenarios using a single battery cell.

Power Controlled Concurrent Transmissions in mmWave WPANs

KIM, Yongsun,KIM, Meejoung,LEE, Wooyong,KANG, Chul-Hee The Institute of Electronics, Information and Comm 2010 IEICE TRANSACTIONS ON COMMUNICATIONS - Vol.93 No.10

<P>This letter considers power-controlled transmission from directional antennas in mmWave wireless personal area network (WPAN) systems. The attributes of these systems are studied; these include the number of concurrent transmissions and the power consumption with different system parameters, such as the antenna's beamwidth and radiating efficiency. Numerical results are presented to show that the power controlled transmission enables more concurrent transmissions than the non-power controlled transmission. The results also show that the number of concurrent transmissions increases as the beamwidth and the path loss component become smaller and the antenna's radiating efficiency increases. In addition, the power controlled system generally uses less power than the non-power controlled transmission set up; the overall analysis is verified by simulation.</P>

Dissolution of studtite [UO₂(O₂)(H₂O)₄] in various geochemical conditions

Kim, Jungjin,Kim, HyunJu,Kim, Won-Seok,Um, Wooyong Elsevier 2018 JOURNAL OF ENVIRONMENTAL RADIOACTIVITY Vol.189 No.-

<P><B>Abstract</B></P> <P>This study determined the dissolution rate of studtite, (UO<SUB>2</SUB>)O<SUB>2</SUB>(H<SUB>2</SUB>O)<SUB>4</SUB>, which can be formed by reaction between H<SUB>2</SUB>O<SUB>2</SUB> and UO<SUB>2</SUB> <SUP>2+</SUP> that leaks from spent nuclear fuel (SNF) in deep geological repositories. The batch dissolution experiments were conducted using synthesized studtite under different solution conditions with varying pHs and concentrations of HCO<SUB>3</SUB> <SUP>−</SUP> and [H<SUB>2</SUB>O<SUB>2</SUB>] in synthetic groundwater. The experimental results suggested that carbonate ligand and H<SUB>2</SUB>O<SUB>2</SUB> in groundwater accelerated the dissolution of studtite and uranium (U) release. Above 10<SUP>−5</SUP> M of H<SUB>2</SUB>O<SUB>2</SUB> initial concentration, the released uranium concentration in solution decreased, possibly as a result of reprecipitation of studtite due to reaction between uranium and H<SUB>2</SUB>O<SUB>2</SUB>. The results will be useful to assess the comprehensive transport of uranium from both nuclear waste and SNF stored in deep geological repositories.</P> <P><B>Highlights</B></P> <P> <UL> <LI> The mechanisms of studtite dissolution by [H<SUP>+</SUP>] and [OH<SUP>−</SUP>] are proposed. </LI> <LI> Carbonate ligand and H<SUB>2</SUB>O<SUB>2</SUB> in groundwater accelerate the dissolution of studtite. </LI> <LI> Dissolved oxygen is not considered to significantly effect studtite dissolution. </LI> <LI> Dominant uranium species in 10<SUP>−3</SUP> M HCO<SUB>3</SUB> <SUP>−</SUP> solution are confirmed using TRLFS analysis. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Clinical Evaluation of Five Commercial Serological SARS-CoV-2 Immunoassays for COVID-19

Wooyong Shin,방해인,Geun Young Yu,Mi-Young Kim,Eui Young Jang,Jung-Ah Kim,Jieun Kim,Rojin Park,신정원,Tae Youn Choi 대한임상검사정도관리협회 2021 Journal of Laboratory Medicine And Quality Assuran Vol.43 No.4

Background: Coronavirus disease 2019 (COVID-19) is a serious infectious disease caused by the highly contagious severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). In this study, three types of kits for the lateral flow assay (LFA) and two types of reagents used in the chemiluminescent immunoassay (CLIA) for serological testing of COVID-19 were evaluated and compared to investigate the current status of antibody testing. Methods: From January 2020 to February 2021, 193 positive and 94 negative samples were tested. For these samples, WonMed COVID-19 immunoglobulin M (IgM)/immunoglobulin G (IgG) (Wonmed, Korea), careUS COVID-19 IgM/IgG (WELLS BIO, Korea), and STANDARD Q COVID-19 IgM/IgG Plus test (SD Biosensors, Korea) kits were used for the LFA, and Anti-SARS-CoV2 Elecsys nucleocapsid (N) and spike (S) (Roche, Switzerland) and ACCESS SARSCoV- 2 IgM and IgG (Beckman Coulter, USA) for the CLIA were compared and evaluated. Results: All kits and reagents except Elecsys showed variable sensitivities of 46.1%–72.0% for IgM, and 85.0%–88.1% for IgG. Elecsys showed a sensitivity of 86.0% for the N antibody and 85.5% for the S antibody. All reagents showed higher sensitivity in samples 14 days after symptom onset than within 14 days (P =0.007). The specificity of LFA and CLIA was 97.9%–100.0%. Conclusions: Most kits and reagents showed low clinical sensitivity at 7–14 days, that is before the antibody was sufficiently produced. When performing a serological test, IgM and IgG should be checked together to obtain sufficient clinical sensitivity, and the test timing should also be applied carefully.

Internet memes of different viewpoints

Wooyong Jin(진우용),Eunsong Kim(김은송),Jung Hwi Roh(노정휘),Ha-young Kim(김하영),Iksoo Kwon(권익수) 담화인지언어학회 2018 담화·인지언어학회 학술대회 발표논문집 Vol.2018 No.11

Removal of Chalk River unidentified deposit (CRUD) radioactive waste by enhanced electrokinetic process

Kim, Won-Seok,Nam, Seongsik,Chang, Seeun,Kim, HyunJu,Um, Wooyong THE KOREAN SOCIETY OF INDUSTRIAL AND ENGINEERING 2018 JOURNAL OF INDUSTRIAL AND ENGINEERING CHEMISTRY -S Vol.57 No.-

<P><B>Abstract</B></P> <P>Decontamination techniques proposed and used to remove Chalk River unidentified deposit (CRUD) in radioactive waste management. In cases of huge volumes of metal or radionuclides contaminated by CRUD, removal of CRUD by mechanical or chemical decontamination is difficult. An advanced electrokinetic process combined with chemical decontamination was applied to remove CRUD and experimentally evaluated. Oxalic acid was used for CRUD removal, and cobalt (Co) released from the CRUD was transferred to the cathode in an electrokinetic reactor. Results indicate that the combined system is efficient for CRUD removal with enhanced, efficiency by use of the cation exchange membrane and zeolite.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Combined decontamination method was developed for CRUD removal. </LI> <LI> Chemical reagent and EK processes were combined to enhance the removal efficiency. </LI> <LI> A huge volume of contaminated metals from NPPs was reduced after decontamination. </LI> <LI> Cobalt ions were removed by zeolite in the EK process after moving to the cathode. </LI> </UL> </P> <P><B>Graphical abstract</B></P> <P>[DISPLAY OMISSION]</P>

Synthesis of Tributyl Phosphate-Coated Hydroxyapatite for Selective Uranium Removal

Kim, HyunJu,Um, Wooyong,Kim, Won-Seok,Chang, Seeun American Chemical Society 2017 INDUSTRIAL & ENGINEERING CHEMISTRY RESEARCH - Vol.56 No.12

<P>Efficient and rapid removal of radioactive contaminants is crucial when they are released into the environment following nuclear accidents. Here, different types of apatite were synthesized using tributyl phosphate (TBP) and tested for the removal of uranium from various solutions using different reaction times and uranium concentrations. The uranium adsorption results showed that uranium adsorption reached a steady state within 24 h in tests open to atmosphere at a slightly alkaline pH in different background solutions. TBP-coated hydroxyapatite removed U better than hydroxyapatite alone did. The U removal mechanism was considered as multilayer adsorption, showing the best fit to the Freundlich isotherm. The maximal U adsorption capacity determined from the Langmuir isotherm is 38 mg of U g<SUP>–1</SUP>. Because of the high U removal efficiency, even at the high pH used in this study, TBP-coated hydroxyapatite appears to be a promising adsorbent for the removal of U from various waste streams as well as for recovery of U from seawater.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/iecred/2017/iecred.2017.56.issue-12/acs.iecr.6b04491/production/images/medium/ie-2016-04491f_0007.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/ie6b04491'>ACS Electronic Supporting Info</A></P>