• Journal of the Korean Physical Society
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• v.80
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• pp.516-525
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• 2022

This study is to assess the clinical use of commercial PerFRACTION^TM for patient-specific quality assurance of volumetric-modulated arc therapy. Forty-six pretreatment verification plans for patients treated using a TrueBeam STx linear accelerator for lesions in various treatment sites such as brain, head and neck (H&N), prostate, and lung were included in this study. All pretreatment verification plans were generated using the Eclipse treatment planning system (TPS). Dose distributions obtained from electronic portal imaging device (EPID), ArcCHECK^TM, and two-dimensional (2D)/three-dimensional (3D) PerFRACTION^TM were then compared with the dose distribution calculated from the Eclipse TPS. In addition, the correlation between the plan complexity (the modulation complexity score and the leaf travel modulation complexity score) and the gamma passing rates (GPRs) of each quality assurance (QA) system was evaluated by calculating Spearman's rank correlation coefficient (r_s) with the corresponding p-values. The gamma passing rates of 46 patients analyzed with the 2D/3D PerFRACTION^TM using the 2%/2 mm and 3%/3 mm criteria showed almost similar trends to those analyzed with the Portal dose imaging prediction (PDIP) and ArcCHECK^TM except for those analyzed with ArcCHECK^TM using the 2%/2 mm criterion. Most of weak or moderate correlations between GPRs and plan complexity were observed for all QA systems. The trend of mean rs between GPRs using PDIP and 2D/3D PerFRACTION^TM for both criteria and plan complexity indices as in the GPRs analysis was significantly similar for brain, prostate, and lung cases with lower complexity compared to H&N case. Furthermore, the trend of mean rs for 2D/3D PerFRACTION^TM for H&N case with high complexity was similar to that of ArcCHECK^TM and slightly lower correlation was observed than that of PDIP. This work showed that the performance of 2D/3D PerFRACTION^TM for pretreatment patient-specific QA was almost comparable to that of PDIP, although there was small difference from ArcCHECK^TM for some cases. Thus, we found that the PerFRACTION^TM is a suitable QA system for pretreatment patient-specific QA in a variety of treatment sites.

• Korean Journal of Soil Science and Fertilizer
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• v.32 no.4
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• pp.429-439
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• 1999

Potentiometric titration data were collected for some humic acids purified from Korean upland and paddy soils over a range of pH (3.0 - 11.0) with $NaNO_3$ background electrolyte concentrations (0.01, 0.10, 0.50 and 1.00 M). The data were applied to model A and V which included both intrinsic heterogeneity of humic materials and electrostatic interaction influences on binding sites. The elemental analysis were conducted for various type of humic samples. The $E_4/E_6$ ratio proposed negative correlation with the total carboxyl groups ($r^2$= 0.9988). The charge ($cmol_c\;kg^{-1}$) on the humic acids became more negative as the ionic strength increased. In both continuous and batch titrations, the ionic strength effect was greater in Namweon series (pH 6.39) than others at pH 5.00. The effect of ionic strength on surface charge appears to be greater in batch titrations. This could suggest that continuous titrations do not represent an equilibrium state and the effects of electrolyte concentration was not fully realized during the course of titrations. Both models described experimental data obtained from continuous and batch titrations well over a range of ionic strengths. Model A is more simpler than model V but adaptes more fitted parameters. Thus, the observed change in apparent binding constants with surface charge is regarded solely due to electrostatic influences rather than functional group heterogeneity. However, Model V is more mechanistically realistic in a number of discrete ligand binding sites.

• Journal of the Korean Chemical Society
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• v.46 no.5
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• pp.407-411
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• 2002

A method to determine lead ion in aqueous media using an optical sensor loaded on a fluorescent optode membrane incoporating a metal ion-selective ionophore, a proton-selective chromoionophore and lipophilic anionic sites has been studied. The effects of pH and thickness of membrane on the fluorescence intensity were investigated. The effects of foreign ions such as $Na^+$, $K^+$, $Mn^{2+}$ and $Zn^{2+}$ on the determination of lead ion were also studied. The linear range in the calibration curve for the determination of lead ion was found to be 5.0${\times}10^-7$ to 5.0${\times}$$10^-3$M and the correlation coefficient in this range was -0.99107 under the optimal experimental conditions. The relative standard deviation of the blank signals was 3.0% and the detection limit of lead ion was 5.0${\times}$$10^-9$M.

• Journal of radiological science and technology
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• v.39 no.2
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• pp.143-148
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• 2016

The purpose of this study was examined the measurement error factor on AMARES of jMRUI method for magnetic resonance spectroscopy (MRS) quantitative analysis by skilled and unskilled observer method and identified the reason of independent observers. The Point-resolved spectroscopy sequence was used to acquired magnetic resonance spectroscopy data of 10 weeks male Sprague-Dawley rat liver. The methylene protons ($(-CH_{2-})n$) of 1.3 ppm and water proton ($H_2O$) of 4.7 ppm ratio was calculated by LCModel software for using the reference data. The seven unskilled observers were calculated total lipid (methylene/water) using the jMRUI AMARES technique twice every 1 week, and we conducted interclass correlation coefficient (ICC) statistical analysis by SPSS software. The inter-observer reliability (ICC) of Cronbach's alpha value was less than 0.1. The average value of seven observer's total lipid ($0.096{\pm}0.038$) was 50% higher than LCModel reference value. The jMRUI AMARES analysis method is need to minimize the presence of the residual metabolite by identified metabolite MRS profile in order to obtain the same results as the LCModel.

• Journal of the Korean Magnetic Resonance Society
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• v.4 no.1
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• pp.19-28
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• 2000

Authors evaluated alterations of observable metabolite ratios between the cerebral lesion and the contralateral region related to the clinical symptomatic side in levodopa-treated Parkinson's disease (PD) and investigated correlation between age in patients with PD and metabolite ratios of the lesion. Patients with levodopa-treated PD (n = 54) and age-matched normal controls (n = 15) underwent magnetic resonance spectroscopy (MRS) examinations using a stimulated echo acquisition mode (STEAM) pulse sequence that provided 2$\times$2$\times$2 cm3 volume of interest in the selected regions of substantia nigra (SN) and putamed-globus pallidus (PG). To evaluate dependence of metabolite ratios on age, we divided into two groups (i.e., younger and older age). We quantitatively measured N-acetylaspartate (NAA), creatine (Cr), choline-containing compounds (Cho), inositols (Ins), and the sum of glutamate (Glx) and GABA levels and obtained proton metabolite ratios relative to Cr using a Marquart algorithm. Compared with the contralateral region, a significant neuronal laterality of the NAA/Cr ratio in the lesion of SN related to the clinical symptomatic side was established (P = 0.01), but was not established in the lesion of PG (P = 0.24). Also, Cho/Cr ratio tended toward significance in the lesion of SN (P = 0.07) and was statistically significant in the lesion of PG(P = 0.01). Compared with that in the younger age group, NAA/Cr ratio in the older age was decreased in the lesion of SN (P = 0.02), while NAA/Cr ratio was not statistically significant in the lesion of PG ( P = 0.21). Significant metabolic alterations of NAA/Cr and Cho/Cr ratios might be closely related with functional changes of neuropathological process in SN and PG of levodopa treated PD and could be a valuable finding for evaluation of the PD. A trend of NAA/Cr reduction, being statistically significant in older patients, could be indicative of more pronounced neuronal damage in the SN of the progressive PD.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• v.36 no.5
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• pp.386-391
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• 2010

Introduction: Bone resorption is a unique function of osteoclasts. Osteoclasts are a specialized macrophage polykaryon whose differentiation is regulated principally by macrophage colony-stimulating factors, receptor activator of nuclear factor ${\kappa}B$ ligand (RANK) ligand, osteoprotegerin (OPG), and interleukins (IL). Reflecting the integrin-mediated signals, osteoclasts develop a specialized cytoskeleton that allows it to establish an isolated micro-environment between itself and the bone, wherein matrix degradation occurs by a process involving proton transport. The levels of IL-1, IL-6, OPG, and prostaglandin $E_2$ ($PGE_2$) expression were evaluated to study the correlations between dental implant teeth and the adjacent teeth. Materials and Methods: The exudate of the gingival crevice acquired from dental implants, adjacent teeth, opposite teeth and contralateral teeth of 24 patients. Results: 1. The levels of IL-1, IL-6, OPG and $PGE_2$ expression in dental implant teeth were higher than those of the contralateral teeth. 2. IL-1 revealed a higher expression level in the adjacent teeth than in dental implant teeth. 3. The dental implant teeth and adjacent teeth did not show a remarkable difference in the level of IL-1 expression. 4. All the other cytokines were strongly expressed in the dental implant compared to the adjacent teeth. Conclusion: These results suggest that there might be close correlation between dental implant teeth and adjacent teeth in terms of the expressions of cytokines that affect the development and regulation of osteoclasts.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.10
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• pp.69-74
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• 2017

In this study, cholesteryl 4-n-alkoxybenzoates (Chol-n), with alkyl groups used for controlling the temperature of transition to the liquid crystal phase, were synthesized, and the effects of the length of the alkyl groups on the physical properties of the liquid crystal compounds were investigated. The chemical structures and thermal and liquid crystalline properties of the synthesized compounds were investigated by Fourier transform infrared spectroscopy (FT-IR), proton nuclear magnetic resonance spectroscopy ($^1H$-NMR), differential scanning calorimetry (DSC), and polarizing optical microscopy (POM). The synthesized compounds showed melting transition temperatures ($T_m$) in the range of $103^{\circ}C$ to $143^{\circ}C$ and all of the compounds except Chol-6 exhibited a wide liquid crystal phase temperature range of about $60^{\circ}C$ to $100^{\circ}C$. No correlation between the number of carbon atoms in the molecule and the thermal properties of the compounds was found. All of the synthesized compounds showed an enantiotropic cholesteric phase, which was accompanied by a chiral smectic phase in the compounds Chol-6, Chol-8, Chol-9, and Chol-10. All of the compounds exhibited thermochromism in the liquid crystal state, and their color changed from red to blue as the temperature was increased.

• Journal of Astronomy and Space Sciences
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• v.34 no.4
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• pp.237-244
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• 2017

Magnetic flux ropes, often observed during intervals of interplanetary coronal mass ejections, have long been recognized to be critical in space weather. In this work, we focus on magnetic flux rope structure but on a much smaller scale, and not necessarily related to interplanetary coronal mass ejections. Using near-Earth solar wind advanced composition explorer (ACE) observations from 1998 to 2016, we identified a total of 309 small-scale magnetic flux ropes (SMFRs). We compared the characteristics of identified SMFR events with those of normal magnetic cloud (MC) events available from the existing literature. First, most of the MCs and SMFRs have similar values of accompanying solar wind speed and proton densities. However, the average magnetic field intensity of SMFRs is weaker (~7.4 nT) than that of MCs (~10.6 nT). Also, the average duration time and expansion speed of SMFRs are ~2.5 hr and 2.6 km/s, respectively, both of which are smaller by a factor of ~10 than those of MCs. In addition, we examined the geoeffectiveness of SMFR events by checking their correlation with magnetic storms and substorms. Based on the criteria Sym-H < -50 nT (for identification of storm occurrence) and AL < -200 nT (for identification of substorm occurrence), we found that for 88 SMFR events (corresponding to 28.5 % of the total SMFR events), substorms occurred after the impact of SMFRs, implying a possible triggering of substorms by SMFRs. In contrast, we found only two SMFRs that triggered storms. We emphasize that, based on a much larger database than used in previous studies, all these previously known features are now firmly confirmed by the current work. Accordingly, the results emphasize the significance of SMFRs from the viewpoint of possible triggering of substorms.

• Journal of the Korean Chemical Society
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• v.54 no.5
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• pp.523-532
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• 2010

The proposed method is simple, sensitive and specific Liquid chromatography-tandem mass spectrometry (LCESI-MS/MS) method for the quantification of Entacapone (EA) in human plasma using Entacapone-d10 (EAD10) as an internal standard (IS). Chromatographic separation was performed on Zorbax SB-C18, $2.1{\times}50\;mm$, $5\;{\mu}m$ column, mobile phase composed of 10 mM Ammonium formate (pH 3.0): Acetonitrile (60:40 v/v), with a flow-rate of 0.7 mL/min, followed by Liquid-liquid extraction. EA and EAD10 were detected with proton adducts at m/z $306.1{\rightarrow}233.1$ and $316.3{\rightarrow}233.0$ in multiple reaction monitoring (MRM) positive mode respectively. The method was validated over a linear concentration range of 1.00 - 2000.00 ng/mL with correlation coefficient ($r^2$) $\geq$ 0.9993. Intra and inter-day Precision within 3.60 to 7.30 and 4.20 to 5.50% and Accuracy within 97.30 to 104.20 and 98.30 to 105.80% proved for EA. This method is successfully applied in the bioequivalence study of healthy Indian human volunteers.

• Korean Journal of Radiology
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• v.22 no.5
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• pp.770-781
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• 2021

Objective: Chemical exchange-dependent saturation transfer (CEST) MRI is sensitive for detecting solid-like proteins and may detect changes in the levels of mobile proteins and peptides in tissues. The objective of this study was to evaluate the characteristics of chemical exchange proton pools using the CEST MRI technique in patients with dementia. Materials and Methods: Our institutional review board approved this cross-sectional prospective study and informed consent was obtained from all participants. This study included 41 subjects (19 with dementia and 22 without dementia). Complete CEST data of the brain were obtained using a three-dimensional gradient and spin-echo sequence to map CEST indices, such as amide, amine, hydroxyl, and magnetization transfer ratio asymmetry (MTR_asym) values, using six-pool Lorentzian fitting. Statistical analyses of CEST indices were performed to evaluate group comparisons, their correlations with gray matter volume (GMV) and Mini-Mental State Examination (MMSE) scores, and receiver operating characteristic (ROC) curves. Results: Amine signals (0.029 for non-dementia, 0.046 for dementia, p = 0.011 at hippocampus) and MTR_asym values at 3 ppm (0.748 for non-dementia, 1.138 for dementia, p = 0.022 at hippocampus), and 3.5 ppm (0.463 for non-dementia, 0.875 for dementia, p = 0.029 at hippocampus) were significantly higher in the dementia group than in the non-dementia group. Most CEST indices were not significantly correlated with GMV; however, except amide, most indices were significantly correlated with the MMSE scores. The classification power of most CEST indices was lower than that of GMV but adding one of the CEST indices in GMV improved the classification between the subject groups. The largest improvement was seen in the MTR_asym values at 2 ppm in the anterior cingulate (area under the ROC curve = 0.981), with a sensitivity of 100 and a specificity of 90.91. Conclusion: CEST MRI potentially allows noninvasive image alterations in the Alzheimer's disease brain without injecting isotopes for monitoring different disease states and may provide a new imaging biomarker in the future.