• The Korean Journal of Nuclear Medicine Technology
• /
• v.17 no.2
• /
• pp.10-14
• /
• 2013

Purpose: Due to developed simultaneous PET/MRI, it has become possible to obtain more anatomical image information better than conventional PET/CT. By the way, in the PET/CT, the linear absorption coefficient is measured by X-ray directly. However in case of PET/MRI, the value is not measured from MRI images directly, but is calculated by dividing as 4 segmentation ${\mu}-map$. Therefore, in this paper, we will evaluate the SUV's difference of attenuation correction PET images from PET/MRI and PET/CT. Materials and Methods: Biograph mCT40 (Siemens, Germany), Biograph mMR were used as a PET/CT, PET/MRI scanner. For a phantom study, we used a solid type $^{68}Ge$ source, and a liquid type $^{18}F$ uniformity phantom. By using VIBE-DIXON sequence of PET/MRI, human anatomical structure was divided into air-lung-fat-soft tissue for attenuation correction coefficient. In case of PET/CT, the hounsfield unit of CT was used. By setting the ROI at five places of each PET phantom images that is corrected attenuation, the maximum SUV was measured, evaluated %diff about PET/CT vs. PET/MRI. In clinical study, the 18 patients who underwent simultaneous PET/CT and PET/MRI was selected and set the ROI at background, lung, liver, brain, muscle, fat, bone from the each attenuation correction PET images, and then evaluated, compared by measuring the maximum SUV. Results: For solid $^{68}Ge$ source, SUV from PET/MRI is measured lower 88.55% compared to PET/CT. In case of liquid $^{18}F$ uniform phantom, SUV of PET/MRI as compared to PET/CT is measured low 70.17%. If the clinical study, the background SUV of PET/MRI is same with PET/CT's and the one of lung was higher 2.51%. However, it is measured lower about 32.50, 40.35, 23.92, 13.92, 5.00% at liver, brain, muscle, fat, femoral head. Conclusion: In the case of a CT image, because there is a linear relationship between 511 keV ${\gamma}-ray$ and linear absorption coefficient of X-ray, it is possible to correct directly the attenuation of 511 keV ${\gamma}-ray$ by creating a ${\mu}$map from the CT image. However, in the case of the MRI, because the MRI signal has no relationship at all with linear absorption coefficient of ${\gamma}-ray$, the anatomical structure of the human body is divided into four segmentations to correct the attenuation of ${\gamma}-rays$. Even a number of protons in a bone is too low to make MRI signal and to localize segmentation of ${\mu}-map$. Therefore, to develope a proper sequence for measuring more accurate attenuation coefficient is indeed necessary in the future PET/MRI.

• Bulletin of the Korean Chemical Society
• /
• v.32 no.spc8
• /
• pp.3090-3093
• /
• 2011

Curcumin is a natural product with antioxidant, anti-inflammatory, antiviral and antifungal functions. As it is known that the excited state intramolecular hydrogen transfer of curcumin are related to its medicinal antioxidant mechanism, we investigated its excited state dynamics by using femtosecond transient absorption spectroscopy in an effort to understand the molecule's therapeutic effect in terms of its photophysics and photochemistry. We found that stronger intermolecular hydrogen bonding with solvents weakens the intramolecular hydrogen bonding and decelerates the dynamical process of the enolic hydrogen. Exceptions are found in methanol and ethylene glycol due to their nature as simultaneous hydrogen bonding donor-acceptor and high viscosity solvent, respectively.

• YAKHAK HOEJI
• /
• v.13 no.1
• /
• pp.1-15
• /
• 1969

A new method of qualitative and quantitative determination of barbiturates in the pharmaceuticals by means of $\alpha$-picoline-copper (II) was studied. Barbiturates in the pharmaceuticals were dissolved in the mixed solvent of 33% $\alpha$-picoline-Carbontetrachloride to yield Complex Compounds of barbiturates-copper (II)-$\alpha$-picoline. Complex Compounds of barbiturates show uniformly maximum absorption at the wavelength of 540m.mu. and wre to be identified at the concentration of 1 X 10$^{-4}$ Mole, and also was to be quantitatively determined at the concentration of 1 X 10$^{-3}$ Mole. By this method barbiturates in the pharmaceuticals could be determined in the presence of various compounds such as sulpyrine, isopropylantipyrine, antipyrine, phenacetin and etc. But Barbiturates could be also determined by this method after seperation with aminopyrine, acetaminophen, acetylsalicylic acid and etc. by column chromatography. And barbiturates and acetylsalicylic acid could be also determined by simultaneous equation while their complex compounds show uniformly each maximum absorption at the Wavelength of 540 m${\mu}$ and 620 m${\mu}$. I.R. spectra of these complex compounds show identification of Barbiturates derivatives. The composition ratio of these complex compounds were : barbiturates : Cu : ${\alpha}$-picoline=2:1:2.

• The Bulletin of The Korean Astronomical Society
• /
• v.41 no.1
• /
• pp.36.1-36.1
• /
• 2016

The physical scenario describing the origin of quasar winds remains largely unsettled due to our failure to account for X-ray weak BAL quasars. We approach this problem by studying the relation between the inner part of the outflow which is likely to be shielding the X-ray emission and thereby helping to drive the UV winds characterised by broad absorption lines (BALs). In particular, we aim to probe the wind-shield connection in the highly X-ray variable BAL quasar PG 2112+059, which has exhibited periods of X-ray weakness and X-ray normality in the past. A set of two 20 ks Chandra observations and two contemporaneous HST observations, separated by at least eight months, combined with a nearly simultaneous archival Chandra-HST observation from 2002, afford us a unique opportunity to study the connection between the shield (which is thought to be responsible for the X-ray absorption) and the ionisation state of the wind (observed as UV BAL features; e.g., C IV and O VI lines) over various timescales.

• Bulletin of the Korean Chemical Society
• /
• v.35 no.4
• /
• pp.1191-1194
• /
• 2014

Imaging Differential Optical Absorption Spectroscopy (Imaging-DOAS) has been utilized in recent years to provide slant column density (SCD) distributions of several trace gas species in the plume. The present study introduces a new method using Imaging-DOAS data to determine two-dimensional plume structure from the plume emissions of power plant in conditions of negligible aerosol effects on radiative transfer within the plume. We demonstrates for the first time that two-dimensional distributions of sulfur dioxide ($SO_2$) and nitrogen dioxide ($NO_2$) in power plant emissions can be determined simultaneously in terms of SCD distribution. The $SO_2$ SCD values generally decreased with increasing distance from the stack and with distance from the center of the plume. Meanwhile, high $NO_2$ SCD was observed at locations several hundred meters away from the first stack due to the ratio change of NO to $NO_2$ in NOx concentration, attributed to the NO oxidation by $O_3$. The results of this study show the capability of the Imaging-DOAS technique as a tool to estimate plume dimensions in power plant emissions.

• Transactions of the Korean hydrogen and new energy society
• /
• v.23 no.5
• /
• pp.429-436
• /
• 2012

Mg and Mg-based alloys are regarded as strong candidate hydrogen storage materials since their hydrogen capacity exceeds that of known metal hydrides. One of the approaches to improve kinetic is addition of metal oxide. In this paper, we tried to improve the hydrogenation properties of Mg-based hydrogen storage composites. The effect of transition metal oxides, such as $Nb_2O_5$ on the kinetics of the Magnesium hydrogen absorption kinetics was investigated. $MgH_x$-5wt.% $Nb_2O_5$ composites have been synthesized by hydrogen induced mechanical alloying. The powder fabricated was characterized by X-ray diffraction (XRD), Field Emission-Scanning Electron Microscopy (Fe-SEM), Energy Dispersive X-ray (EDX), BET and simultaneous Thermo Gravimetric Analysis / Differential Scanning Calorimetry (TG/DSC) analysis. The Absorption / desorption kinetics of $MgH_x$-5wt.% $Nb_2O_5$ (type I and II) are determined at 423, 473, 523, 573 and 623 K.

• Transactions of the Korean hydrogen and new energy society
• /
• v.22 no.6
• /
• pp.780-786
• /
• 2011

Mg hydride had high hydrogen capacity (7.6%), lightweight and low cost materials and it was promising hydrogen storage material at high temperature. However, commercial applications of the Mg hydride are currently hindered by its high absorption/desorption temperature, and very slow reaction kinetics. one of the approaches to improve the kinetic is $MgH_x$ intermixed with carbon. And it shows that carbon and carbon allotropes have a beneficial effect on hydrogen sorption in Mg. The graphene is a kind of carbon allotropes which is easily desorbed reaction at low temperatures because its reaction is exothermic. In this work, the effect of graphene concentration on the kinetics of Mg hydrogen absorption reaction was investigated. The $MgH_x$-Graphene composites has been prepared by hydrogen induced mechanical alloy (HIMA). The synthesized powder was characterized by XRD and simultaneous TG, DSC analysis. The hydrogenation behaviors were evaluated by using a sievert's type automatic PCT apparatus. In this research, results of kinetic profiles exhibit hydrogen absorption rate of $MgH_x$-5wt.% and 10wt.% graphene composite, as 1.25wt.%/ms, 10.33wt.%/ms against 0.88wt.%/ms for $MgH_x$ alone at 473K.

• Environmental Engineering Research
• /
• v.24 no.3
• /
• pp.389-396
• /
• 2019

The electrical energy consumption (EEC) in removal of NO by a $UV/H_2O_2$ oxidation process was introduced and related to removal efficiency of this gas. The absorption-reaction of NO was conducted in a bubble column reactor in the presence of $SO_2$. The variation in NO removal efficiency was investigated for various process parameters including NO and $SO_2$ inlet concentrations, initial concentration of $H_2O_2$ solution and gas flow rate. EEC values were obtained in these different conditions. The removal efficiency was increased from about 22% to 54.7% when $H_2O_2$ concentration increased from 0.1 to 1.5 M, while EEC decreased by about 70%. However, further increase in $H_2O_2$ concentration, from 1.5 to 2, had no significant effect on NO absorption and EEC. An increase in NO inlet concentration, from 200 to 500 ppm, decreased its removal efficiency by about 10%. However, EEC increased from $2.9{\times}10^{-2}$ to $3.9{\times}10^{-2}kWh/m^3$. Results also revealed that the presence of $SO_2$ had negative effect on NO removal percentage and EEC values. Some experiments were conducted to investigate the effect of $H_2O_2$ solution pH. The changing of pH of oxidation-absorption medium in the ranges between 3 to 10, had positive and negative effects on removal efficiency depending on pH value.

• Proceedings of the Korean Society of Propulsion Engineers Conference
• /
• 2004.03a
• /
• pp.802-806
• /
• 2004

For the protection of the local air quality and the global atmosphere, the emissions of trace species including nitric oxides (NO and NO$_2$) from gas turbines are regulated by local governments and by the International Civil Aviation Organization. In-situ measurements of such species are needed not only for the development of advanced low-emission combustion concepts but also for providing emissions data required for the sound assessment of the effects of the emissions on environment. We have been developing a laser absorption system that has a capability of simultaneous determination of NO and NO$_2$concentrations in the exhaust jets from aero gas turbines. A diode laser operating near 1.8 micrometer is used for the detection of NO while a separated visible tunable diode laser operating near 676 nanometers is used for NO$_2$. The sensitivities at elevated temperature conditions were determined for simulated gas mixtures heated up to 500K in a heated cell of a straight 0.5 m optical path. Sensitivity limits estimated as were 30 ppmv-m and 3.7 ppmv-m for NO and NO$_2$, respectively, at a typical exhaust gas temperature of 800K. Experiments using the simulated exhaust flows have proven that $CO_2$ and $H_2O$ vapor - both major combustion products - do not show any interference in the NO or NO$_2$ measurements. The measurement system has been applied to the NO/NO$_2$ measurements in NO and NO$_2$ doped real combustion gas jets issuing from a rectangular nozzle having 0.4 m optical path. The lower detection limits of the system were considerably decreased by using a multipass optical cell. A pair of off-axis parabola mirrors successfully suppressed the beam steering in the combustion gas jets by centralizing the fluctuating beam in sensor area of the detectors.

• Journal of computational fluids engineering
• /
• v.9 no.2
• /
• pp.43-51
• /
• 2004

Interaction between fluid flow and thermal radiation has received considerable attention due to its numerous applications in engineering field. In this case the thermofluid properties of radiating fluid vary with the variation of temperature field caused by absorption and emission of radiant heat. To analyze the radiation heat transfer in radiating fluid, the simultaneous solution of the radiative transfer equation (RTE) and the fluid dynamics equations is required. This means that the numerical procedure used for the RTE must be computationally efficient to permit its inclusion in the other submodels, and must be compatible with the other transport equations. The finite volume method (FVM) and the discrete ordinates method (DOM) are usually employed to simulate radiation problems in generalized coordinates. These two representative methods are examined and compared, especially in view of the numerical integration of the radiation intensity over solid angle. The FVM shows better accuracy than the DOM owing to less constraints of the selection of control angle.