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INTUITIONISTIC FUZZY SUBGROUPS
AHN, TAE-CHON,HUR, KUL,JANG, KYUNG-WON,ROH, SEOK-BEOM 호남수학회 2006 호남수학학술지 Vol.28 No.1
We discuss various types of sublattice of the lattice of intuitionistic fuzzy subgroups of a given group. We prove that a special class of intuitionitic fuzzy normal subgroups constitutes a modular sublattice of the lattice of intuitionistic fuzzy subgroups.
Jang, Jun Hee,Lee, Jaewoo,Jung, Seon-Yeop,Choi, Dong-Chan,Won, Young-June,Ahn, Kyung Hyun,Park, Pyung-Kyu,Lee, Chung-Hak Elsevier 2015 Separation and purification technology Vol.156 No.2
<P><B>Abstract</B></P> <P>Recently, membrane surface patterning has attracted much attention as an innovative alternative to control membrane fouling that occurs with membrane filtration used in water and wastewater treatment. However, limited attention has been focused on patterned membranes with nano-scale features due to their difficult fabrication. As a result, there is a lack of research on membrane fouling by particle deposition occurring with a wide range of pattern sizes. In this study, we prepared patterned membranes with nano-scale hexagonally packed arrays using nanoimprint lithography as well as micro-scale patterned membranes. Filtration tests were conducted using the membranes in cross-flow ultrafiltration to demonstrate the effect of the size ratio of particles to membrane patterns on fouling by particle deposition on the membrane surface. We found that particle deposition was most efficiently mitigated by the patterned membranes when the size ratio was approximately 3. On the other hand, when the size ratio was much smaller than 3, particle deposition was significant and was nearly as much as that of non-patterned membranes. In addition, when the size ratio was larger than 3, particle deposition increased with the increase in the size ratio. We explained the correlation between particle deposition and the size ratio of particles to membrane patterns in terms of shear stress near the surface of the membrane patterns using a computational fluid dynamics simulation technique. We anticipate that this study will provide a deeper understanding of the particle deposition phenomena in nano- and micro-patterned membrane filtration.</P> <P><B>Highlights</B></P> <P> <UL> <LI> We prepared nano- and micro-patterned membranes using a nanoimprint lithography method. </LI> <LI> We conducted membrane filtration tests using polystyrene latex particles. </LI> <LI> We demonstrated the effect of the size ratio of particles to patterns on particle deposition. </LI> <LI> We calculated shear stress near the membrane surface based on computational fluid dynamics. </LI> <LI> We explained the correlation between particle deposition and the size ratio in terms of shear stress. </LI> </UL> </P>
Ahn, Junsung,Choi, Sungjun,Yoon, Kyung Joong,Son, Ji-Won,Kim, Byung-Kook,Lee, Jong-Ho,Jang, Ho Won,Kim, Hyoungchul American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.49
<P>We explored oxygen-ion transport in highly doped CeO2 through density-functional theory calculations. By applying biaxial strain to 18.75 mol % Ceo(2):Gd, we predicted the average migration-barrier energy with six different pathways, with results in good agreement with those of experiments. Additionally, we found that the migration-barrier energy could be lowered by increasing the tetrahedron volume,, including the space occupied by the oxygen vacancy. Our results indicate that the tetrahedron volume can be expanded by larger codoliants, as well as biaxial tensile strain: Thus, the combination of thin-film structure and codoping could offer a new approach to accelerate oxygen-ion transport.</P>
Reproducibility of Apparent Diffusion Coefficient Measurements in Malignant Breast Masses
Jang, Mijung,Kim, Sun Mi,Yun, Bo La,Ahn, Hye Shin,Kim, Soo Yeon,Kang, Eunyoung,Kim, Sung-Won The Korean Academy of Medical Sciences 2015 JOURNAL OF KOREAN MEDICAL SCIENCE Vol.30 No.11
<P>This study aimed to evaluate the reproducibility of apparent diffusion coefficient (ADC) measurements in malignant breast masses, and to determine the influence of mammographic parenchymal density on this reproducibility. Sixty-six patients with magnetic resonance findings of the mass were included. Two breast radiologists measured the ADC of the malignant breast mass and the same area on the contralateral normal breast in each patient twice. The effects of mammographic parenchymal density, histology, and lesion size on reproducibility were also assessed. There was no significant difference in the mean ADC between repeated measurements in malignant breast masses and normal breast tissue. The overall reproducibility of ADC measurements was good in both. The 95% limits of agreement for repeated ADCs were approximately 30.2%-33.4% of the mean. ADC measurements in malignant breast masses were highly reproducible irrespective of mass size, histologic subtype, or coexistence of microcalcifications; however, the measurements tended to be less reproducible in malignant breast masses with extremely dense parenchymal backgrounds. ADC measurements in malignant breast masses are highly reproducible; however, mammographic parenchymal density can potentially influence this reproducibility.</P>
Jang, Kihun,Lee, Sung-Won,Yu, Seongil,Salunkhe, Rahul R.,Chung, Ildoo,Choi, Sungmin,Ahn, Heejoon Korean Chemical Society 2014 Bulletin of the Korean Chemical Society Vol.35 No.10
$Mn_3O_4$/multi-walled carbon nanotube (MWCNT) composites are prepared by chemically synthesizing $Mn_3O_4$ nanoparticles on a MWCNT film at room temperature. Structural and morphological characterization has been carried out using X-ray diffraction (XRD) and scanning and transmission electron microscopies (SEM and TEM). These reveal that polycrystalline $Mn_3O_4$ nanoparticles, with sizes of about 10-20 nm, aggregate to form larger nanoparticles (50-200 nm), and the $Mn_3O_4$ nanoparticles are attached inhomogeneously on MWCNTs. The electrochemical behavior of the composites is analyzed by cyclic voltammetry experiment. The $Mn_3O_4$/MWCNT composite exhibits a specific capacitance of $257Fg^{-1}$ at a scan rate of $5mVs^{-1}$, which is about 3.5 times higher than that of the pure $Mn_3O_4$. Cycle-life tests show that the specific capacitance of the $Mn_3O_4$/MWCNT composite is stable up to 1000 cycles with about 85% capacitance retention, which is better than the pure $Mn_3O_4$ electrode. The improved supercapacitive performance of the $Mn_3O_4$/MWCNT composite electrode can be attributed to the synergistic effects of the $Mn_3O_4$ nanoparticles and the MWCNTs, which arises not only from the combination of pseudocapacitance from $Mn_3O_4$ nanoparticles and electric double layer capacitance from the MWCNTs but also from the increased surface area, pore volume and conducting property of the MWCNT network.
Pediatric Emergency Department Utilization and Coronavirus Disease in Daegu, Korea
Jang Kyung Mi,Ahn Ji Young,Choi Hee Joung,Lee Sukhee,Kim Dongsub,Lee Dong Won,Choe Jae Young 대한의학회 2021 Journal of Korean medical science Vol.36 No.1
Background: Limited data exist on children's utilization of the emergency department (ED) in the ongoing coronavirus disease 2019 (COVID-19) pandemic. Thus, we aimed to examine ED utilization among pediatric patients and the impact of COVID-19 in one large city affecte by the outbreak. Methods: This retrospective study included data from six EDs in Daegu, Korea. We compare the demographic and clinical data of patients presenting to the ED during the COVID-19 pandemic (February 1st–June 30th 2020) with those of patients who visited the ED in this period during 2018 and 2019. Results: Fewer patients, particularly children visited the EDs during the study period in 202 than those in the previous (2018/2019) year period: the number of adult patient decreased by 46.4% and children by 76.9%. Although the number of patients increased from the lowest point of the decrease in March 2020, the number of pediatric patients visiting the ED remained less than half (45.2%) in June 2020 compared with that of previous years. The proportion of patients with severe conditions increased in adults, infants, and school-aged children, and consequently resulted in increased ambulance use and higher hospitalization rates. Fewer infants and young children but more school-aged children visited the ED with febrile illnesses in 2020 than in 2018/2019. Conclusion: The COVID-19 pandemic has led to a substantial decrease in pediatric ED utilization. These findings can help reallocate human and material resources in the EDs during infectious disease outbreaks.