철도정비부지 내 매립된 폐기물에 의해 중금속으로 오염된 토양의 인체위해성 평가

Hatsue Minato Braatz,정민정,문세흠,박진규 유기성자원학회 2019 유기물자원화 Vol.27 No.3

본 연구에서는 대규모 철도부지를 상업부지로 개발함에 따라 과거 부지 내부에 산업 폐기물 등이 부적절하게처리되어 중금속 폐기물로 오염된 토양의 Cu, Pb, Zn, Ni 에 대한 인체 위해성 평가를 수행하였다. 위해성 평가는토양의 복원 및 복원과정에서 필요한 고려요소를 도출하는데 주요한 과정이다. 본 연구에서는 위해성 평가를 위해환경부 위해성평가지침을 준용하여 노출농도 결정, 노출량 산정, 발암 및 비발암 위해도를 결정하였다. 이를 통해철도부지의 중금속 오염토양의 인체 위해성 평가 결과를 제시하였다. 노출농도 산정결과 토양내 중금속 함량은621.3 Cu mg/kg, 2,824.5 Pb mg/kg, 1,559.1 Zn mg/kg, 45 Ni mg/kg이고, 독성금속별 인체 노출량 결과, 노출경로별로는토양의 실외비산 > 토양섭취 > 토양 접촉 순으로 나타났으며, 오염물질별로는 Pb > Zn > Cu > Ni 순으로 나타났다. 발암위해도 평가 결과, USEPA에서 제시한 허용발암위해도(TCR > 10-6) 보다 높게 나타났으며, 독성위해도(비발암성) 평가 결과, HI 지수(HI< 1.0)도 성인 3.5, 어린이 4.85, Cu 1.94 ~ 2.16, Pb 1.37 ~ 2.90으로 나타났다. 따라서 대상부지의중금속으로 오염된 토양의 복원관리가 필요할 것으로 판단된다. This study carried out a human risk assessment of Cu, Pb, Zn and Ni contained in soil contaminated by improperly buried heavy metal wastes in railway sites. The purpose of the human risk assessment is to derive the need for soil remediation and factors that should be considered during soil remediation. Risk assessment was performed in accordance with the Environment Ministry's Risk Assessment Guidelines. The results of the human risk assessment of contaminated heavy metal soil contaminated by improperly buried waste in the railway site were presented after the process of determining exposure concentration, calculating exposure, and determining carcinogenic hazards. The heavy metal content of soil is 621.3 Cu mg/kg, 2,824.5 Pb mg/kg, 1,559.1 Zn mg/kg and 45 Ni mg/kg, which is the exposure concentration of the target contaminant. The results of human exposure according to exposure pathways were high in the order of soil outdoor dust >soil ingestion >soil contact, and Pb >Zn >Cu >Ni were higher in order of contaminant. The carcinogenic and noncarcinogenic risks of soil contaminated with heavy metal waste were higher than the allowable carcinogenic risks (TCR> 10-6) and the risk index (Hi < 1.0) suggested by USEPA. Therefore, the site needs to be remediated.

SEM-EDS와 화학계량학 분석을 이용한 산업폐기물과 토양의 구분

Hatsue Minato Braatz,박진규,김란희,문세흠,정민정 한국폐기물자원순환학회 2019 한국폐기물자원순환학회지 Vol.36 No.8

Until a couple of years ago, industrial solid waste (ISW), which is produced in the process of maintaining and repairingmachines, was dumped below industrial areas, where it mixed with the soil. To redevelop such affected areas, ISW-soilmixing materials should be identified as components of industrial waste or soil to establish a strategy for waste treatment. However, proper identification of some industrial wastes (such as coal ash) and soil can be challenging and confusing. Therefore, in this study, we suggest a method to determine whether a material (referred to as “suspicious substance”) isa component of ISW or soil to achieve proper waste treatment. Samples were collected from a railroad depot. First, theelemental compositions of the suspicious substances were determined with scanning electron microscopy-energy dispersivespectroscopy. Second, the substances were grouped based on their chemical profiles by conducting hierarchical clusteranalysis. Finally, the elemental compositions of the soil samples obtained from the study site were compared to those ofthe groups to identify the soil.

THE MEGAMASER COSMOLOGY PROJECT. IX. BLACK HOLE MASSES FOR THREE MASER GALAXIES

Gao, F.,Braatz, J. A.,Reid, M. J.,Condon, J. J.,Greene, J. E.,Henkel, C.,Impellizzeri, C. M. V.,Lo, K. Y.,Kuo, C. Y.,Pesce, D. W.,Wagner, J.,Zhao, W. American Astronomical Society 2017 The Astrophysical journal Vol.834 No.1

<P>As part of the Megamaser Cosmology Project, we present VLBI maps of nuclear water masers toward five galaxies. The masers originate in sub-parsec circumnuclear disks. For three of the galaxies, we fit Keplerian rotation curves to estimate their supermassive black hole (SMBH) masses, and determine (2.9 +/- 0.3) x 10(6)M(Theta) for J0437+2456, (1.7 +/- 0.1) x 10(7)M(Theta) for ESO 558-G009, and (1.1 +/- 0.2) x 10(7)M(Theta) for NGC 5495. In the other two galaxies, Mrk 1029 and NGC 1320, the geometry and dynamics are more complicated and preclude robust black hole mass estimates. Including our new results, we compiled a list of 15 VLBI-confirmed disk maser galaxies with robust SMBH mass measurements. With this sample, we confirm the empirical relation of R-out proportional to 0.3M(SMBH) reported in Wardle & Yusef-Zadeh. We also find a tentative correlation between maser disk outer radii and Wide-Field Infrared Survey Explorer luminosity. We find no correlations of maser disk size with X-ray 2-10 keV luminosity or [O III] luminosity.</P>

Economical control of indoor air quality in underground metro station using an iterative dynamic programming-based ventilation system

Kim, Min Jeong,Braatz, Richard D.,Kim, Jeong Tai,Yoo, Chang Kyoo Sage Publications 2016 Indoor and Built Environment Vol.25 No.6

Enhancing the H₂O Megamaser Detection Rate Using Optical and Mid-infrared Photometry

Kuo, C. Y.,Constantin, A.,Braatz, J. A.,Chung, H. H.,Witherspoon, C. A.,Pesce, D.,Impellizzeri, C. M. V.,Gao, F.,Hao, Lei,Woo, J.-H.,Zaw, Ingyin American Astronomical Society 2018 The Astrophysical journal Vol.860 No.2

<P>Water megamasers from circumnuclear disks in galaxy centers provide the most accurate measurements of supermassive black hole masses and uniquely probe the subparsec accretion processes. At the same time, these systems offer independent crucial constraints of the Hubble constant in the nearby universe, and thus, the arguably best single constraint on the nature of dark energy. The chances of finding these golden standards are, however, abysmally low, at less than or similar to 3% overall for any level of water maser emission detected at 22 GHz and less than or similar to 1% for those exhibiting disk-like configuration. We provide here a thorough summary of the current state of detection of water megamaser disks along with a novel investigation of the likelihood of increasing their detection rates based on a multivariate parameter analysis of the optical and mid-infrared (mid-IR) photometric properties of the largest database of galaxies surveyed for 22 GHz emission. We find that galaxies with water megamaser emission tend to be associated with strong emission in all Wide-field Infrared Survey Explorer mid-IR wavelengths, with the strongest enhancement in the W4 band, at 22 mu m, as well as with previously proposed and newly found indicators of active galactic nucleus strength in the mid-IR, such as red W1 - W2 and W1 - W4 colors, and the integrated mid-IR luminosity of the host galaxy. These trends offer a potential boost of the megamaser detection rates to 6%-15%, or a factor of 2-8 relative to the current rates, depending on the chosen sample selection criteria, while fostering real chances for discovering. 20 new megamaser disks.</P>

State Estimation for a Carbon Nanotube-based Sensor Array System

Hong Jang,Jay H. Lee,Richard D. Braatz 제어로봇시스템학회 2015 제어로봇시스템학회 국제학술대회 논문집 Vol.2015 No.10

This paper proposes state estimation methods for tracking a time-varying local concentration of target molecules from the carbon-nanotube (CNT)-based sensing system. The signals triggered by adsorption/desorption events of a trace of the proximate target molecules on the sensors show strongly stochastic behavior. The stochastic nature can be modelled by the chemical master equation (CME) describing the time evolution of the probabilities for all the possible numbers of adsorbed molecules. The adsorption rate on each sensor is proportional to the local concentration, thus connecting the sensor signal to it. At the macroscopic level, the concentration, which is the state, evolves according to the continuum equation represented by ordinary differential equations (ODEs). Various state estimation methods including the Kalman filter (KF), particle filter (PF), and moving horizon estimator (MHE) are designed for the system with highly stochastic, non-Gaussian measurements. Their performances are compared for single sensor as well as multiple sensors in the neighborhood that shares same concentration dynamics.

Estimation of local concentration from measurements of stochastic adsorption dynamics using carbon nanotube-based sensors

이재형,Hong Jang,Richard D. Braatz 한국화학공학회 2016 Korean Journal of Chemical Engineering Vol.33 No.1

This paper proposes a maximum likelihood estimation (MLE) method for estimating time varying local concentration of the target molecule proximate to the sensor from the time profile of monomolecular adsorption and desorption on the surface of the sensor at nanoscale. Recently, several carbon nanotube sensors have been developed that can selectively detect target molecules at a trace concentration level. These sensors use light intensity changes mediated by adsorption or desorption phenomena on their surfaces. The molecular events occurring at trace concentration levels are inherently stochastic, posing a challenge for optimal estimation. The stochastic behavior is modeled by the chemical master equation (CME), composed of a set of ordinary differential equations describing the time evolution of probabilities for the possible adsorption states. Given the significant stochastic nature of the underlying phenomena, rigorous stochastic estimation based on the CME should lead to an improved accuracy over than deterministic estimation formulated based on the continuum model. Motivated by this expectation, we formulate the MLE based on an analytical solution of the relevant CME, both for the constant and the time-varying local concentrations, with the objective of estimating the analyte concentration field in real time from the adsorption readings of the sensor array. The performances of the MLE and the deterministic least squares are compared using data generated by kinetic Monte Carlo (KMC) simulations of the stochastic process. Some future challenges are described for estimating and controlling the concentration field in a distributed domain using the sensor technology.

Fast moving horizon estimation for a distributed parameter system

Hong Jang,Kwang-Ki K. Kim,Jay H. Lee,Richard D. Braatz 제어로봇시스템학회 2012 제어로봇시스템학회 국제학술대회 논문집 Vol.2012 No.10

Partial differential equations (PDEs) pose a challenge for control engineers, both in terms of theory and computational requirements. PDEs are usually approximated by ordinary differential or partial difference equations via the finite difference method, resulting in a high-dimensional state-space system. The obtained system matrix is often symmetric, which allows this high-dimensional system to be decoupled into a set of single-dimensional systems using the state coordinate transformation defined by a singular value decomposition. Any linear constraints in the original control problem can also be simplified by replacement by an ellipsoidal constraint. This reformulated moving horizon estimation (MHE) problem can be solved in orders of magnitude lower computation time than the original MHE problem, by employing an analytical solution obtained by moving the ellipsoidal constraint to the objective function as a penalty weighted by a decreasing penalty parameter. The proposed MHE algorithm is demonstrated for a one-dimensional diffusion in which the concentration field is estimated using distributed sensors.

MEGAMASER DISKS REVEAL A BROAD DISTRIBUTION OF BLACK HOLE MASS IN SPIRAL GALAXIES

Greene, J. E.,Seth, A.,Kim, M.,Lä,sker, R.,Goulding, A.,Gao, F.,Braatz, J. A.,Henkel, C.,Condon, J.,Lo, K. Y.,Zhao, W. American Astronomical Society 2016 ASTROPHYSICAL JOURNAL LETTERS - Vol.826 No.2

<P>We use new precision measurements of black hole (BH) masses from water megamaser disks to investigate scaling relations between macroscopic galaxy properties and supermassive BH mass. The megamaser-derived BH masses span 10(6)-10(8) M-circle dot, while all the galaxy properties that we examine (including total stellar mass, central mass density, and central velocity dispersion) lie within a narrower range. Thus, no galaxy property correlates tightly with M-BH in similar to L* spiral galaxies as traced by megamaser disks. Of them all, stellar velocity dispersion provides the tightest relation, but at fixed sigma* the mean megamaser M-BH are offset by -0.6 +/- 0.1 dex relative to early-type galaxies. Spiral galaxies with non-maser dynamical BH masses do not appear to show this offset. At low mass, we do not yet know the full distribution of BH mass at fixed galaxy property; the non-maser dynamical measurements may miss the low-mass end of the BH distribution due to an inability to resolve their spheres of influence and/or megamasers may preferentially occur in lower-mass BHs.</P>