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result(s) for
"Moon, Nam-Won"
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LINEAR POLARIZATION SUM IMAGING IN PASSIVE MILLIMETER-WAVE IMAGING SYSTEM FOR TARGET RECOGNITION
by
Kim, Yong-Hoon
,
Kim, Won-Gyum
,
Moon, Nam-Won
in
Imaging systems
,
Methods
,
Polarization (Electricity)
2013
In passive millimeter-wave imaging systems used indoors, the radiometric temperature contrast is barely enough for coarse object detection, being usually insufficient for recognition due to the absence of cold sky. The image contrast results from a combination of emissivity and reflectivity which are dependent on the dielectric constant of objects, the angle of incidence, and the polarization direction. To improve the capability of target recognition, we proposed the linear polarization sum imaging method which is based on the combination of the different polarization images for increasing the intensity contrast between the target area and the background area. In order to capture the linear polarization sum images of a metal sphere, a metal and a ceramic cup, we designed W-band quasi-optical imaging system which can generate the polarization dependent images by manually changing the linear polarization direction of its radiometer receiver from 0 to π/2 by the step size of π/8. The theoretical and experimental results of the linear polarization sum imaging show that it is capable for achieving good image quality enough to recognize the target.
Journal Article
LOSS MEASURING OF LARGE APERTURE QUASI-OPTICS FOR W-BAND IMAGING RADIOMETER SYSTEM
2012
A loss of large aperture quasi-optics which consist of a lens and a feed antenna is firstly measured using a radiometer receiver via the modified reference control method for a W-band imaging radiometer system. The quasi-optical loss is mainly decided by the dielectric loss of the lens with good quasi-optical transformation efficiency between the lens and the feed antenna. The quasi-optics composed of an aspheric lens and a dielectric rod antenna are designed for high resolution, low aberration, and compact size. The fabricated quasi-optics with the aperture diameter of 500 mm have the quasi-optical transformation efficiency of more than 95%. The radiometer receiver is designed applying a total power type and a direct conversion topology for simplicity, compact size and low temperature sensitivity. The manufactured receiver has the temperature sensitivity less than 1 K for both a hot source and a cold source. The calculated and measured results of the quasi-optics are very well matched by approximately 1.6dB. The expected measurement errors by the reference control method are also analyzed as the functions of the characteristic parameters of the radiometer receiver.
Journal Article
Forecasting Daily Solar Radiation Using CEEMDAN Decomposition-Based MARS Model Trained by Crow Search Algorithm
by
Maleki, Niloofar
,
Kim, Sungwon
,
Ashrafian, Ali
in
Accuracy
,
Algorithms
,
Alternative energy sources
2019
The precise forecasting of daily solar radiation (DSR) is receiving prominent attention among thriving solar energy studies. In this study, three standalone models, including gene expression programing (GEP), multivariate adaptive regression splines (MARS), and self-adaptive MARS (SaMARS), were evaluated to forecast DSR. A SaMARS model was classified as MARS model when using the crow search algorithm (CSA). In addition, to overcome the limitations of the standalone models, the complete ensemble empirical mode decomposition with adaptive noise (CEEMDAN) was employed to enhance the accuracy of DSR forecasting. Therefore, three hybrid models including CEEMDAN-GEP, CEEMDAN-MARS, and CEEMDAN-SaMARS were proposed to forecast DSR in Busan and Incheon stations in South Korea. The performance of proposed models were evaluated and affirmed that the accuracy of the CEEMDAN-SaMARS model (NSE = 0.878–0.883) outperformed CEEMDAN-MARS (NSE = 0.819–0.818), CEEMDAN-GEP (NSE = 0.873–0.789), SaMARS (NSE = 0.846–0.769), MARS (NSE = 0.819–0.758), and GEP (NSE = 0.814–0.755) models at both stations. Therefore, it can be concluded that the optimized CEEMDAN-SaMARS model significantly enhanced the accuracy of DSR forecasting compared to that of standalone models.
Journal Article
Gardeniae Fructus Attenuates Thioacetamide-Induced Liver Fibrosis in Mice via Both AMPK/SIRT1/NF-κB Pathway and Nrf2 Signaling
by
Choi, Hyukjae
,
Lee, Jin A
,
Shin, Mi-Rae
in
AMP-activated protein kinase
,
AMPK/SIRT1 pathway
,
Biochemistry
2021
Liver fibrosis, which means a sort of the excessive accumulation of extracellular matrices (ECMs) components through the liver tissue, is considered as tissue repair or wound-healing status. This pathological stage potentially leads to cirrhosis, if not controlled, it progressively results in hepatocellular carcinoma. Herein, we investigated the pharmacological properties and underlying mechanisms of Gardeniae Fructus (GF) against thioacetamide (TAA)-induced liver fibrosis of mice model. GF not only attenuated hepatic tissue oxidation but also improved hepatic inflammation. We further confirmed that GF led to ameliorating liver fibrosis by ECMs degradations. Regarding the possible underlying mechanism of GF, we observed GF regulated epigenetic regulator, Sirtuin 1 (SIRT1), in TAA-injected liver tissue. These alterations were well supported by SIRT1 related signaling pathways through regulations of its downstream proteins including, AMP-activated protein kinase (AMPK), p47phox, NADPH oxidase 2, nuclear factor erythroid 2–related factor 2 (Nrf2), and heme oxygenase-1, respectively. To validate the possible mechanism of GF, we used HepG2 cells with hydrogen peroxide treated oxidative stress and chronic exposure conditions via deteriorations of cellular SIRT1. Moreover, GF remarkably attenuated ECMs accumulations in transforming growth factor–β1-induced LX-2 cells relying on the SIRT1 existence. Taken together, GF attenuated liver fibrosis through AMPK/SIRT1 pathway as well as Nrf2 signaling cascades. Therefore, GF could be a clinical remedy for liver fibrosis patients in the future.
Journal Article
X-ray Diffraction Analysis of Clay Particles in Ancient Baekje Black Pottery: Indicator of the Firing Parameters
2021
An X-ray diffraction (XRD) analysis was conducted after separating clay particles from three shards, to analyze the production technique of black pottery excavated from a historical site of ancient Baekje in Seoul, South Korea. Through the analysis, clay minerals and iron oxides that were not recognized in the XRD patterns of the bulk powder samples were identified. A pottery type with a blackened portion from the surface to the margin and the core was estimated to have been produced in a reduction firing environment of less than 900 °C, by detecting illite and magnetite. As for the other blackened pottery, a brown soil color remained in the core, and the presence of illite and kaolin was confirmed. In addition, while magnetite was detected on the black surface and margin, hematite was detected in the core. These results confirm that this type of blackened pottery was produced through reduction firing at a temperature below 550 °C. In particular, the results indicate that there is a new category of pottery, produced by firing at lower temperatures in a reduction atmosphere, previously not reported by research on ancient Baekje black pottery, which could be discovered due to its specific clay particles.
Journal Article
Anti-Inflammatory Butenolides from a Marine-Derived Streptomyces sp. 13G036
by
Choi, Hyukjae
,
Gao, Ming
,
Lee, Jae-Eon
in
Alzheimer's disease
,
anti-inflammatory activity
,
Anti-inflammatory agents
2022
Butenolides are a family of lactones containing a double bond and have been frequently found in the extracts of Streptomyces bacterial species with various pharmacological activities. In this study, seven butenolides (1–7) were discovered and isolated from the culture broth of a marine-derived Streptomyces sp. 13G036 based on a molecular networking analysis. Among the seven isolates, compound 7 was first isolated as a natural product in this study. The structures of compounds 1–7 were determined by combined analysis of 1D/2D Nuclear Magnetic Resonance (NMR) spectra, Mass Spectrometry (MS) spectra and electronic circular dichroism (ECD) data. Compounds 1–6 showed potential anti-inflammatory activities by inhibiting the production of nitric oxide (NO), tumor necrosis factor-α (TNF-α) and interleukine-6 (IL-6) in lipopolysaccharide-stimulated macrophages.
Journal Article
Assessing distributed groundwater recharge rate using integrated surface water-groundwater modelling: application to Mihocheon watershed, South Korea
by
Kim, Nam-Won
,
Lee, Jeongwoo
,
Sophocleous, Marios
in
Aquatic Pollution
,
Computer simulation
,
Earth and Environmental Science
2010
A method of estimating groundwater recharge, based on water-balance components using the SWAT-MODFLOW model (an integrated surface water-groundwater model), is described. A multi-reservoir storage routing module is suggested instead of a single storage routing module in SWAT; this represents a more realistic delay in the travel of water through the vadose zone. By using this module, the parameter related to the delay time can be optimized by checking the correlation between simulated recharge and observed groundwater levels. The final step of this procedure is to compare simulated groundwater levels as well as the simulated watershed stream flow with the observed groundwater levels and watershed stream flow. This method is applied to the Mihocheon watershed in South Korea to estimate spatio-temporal groundwater recharge distribution. The computed annual recharge rate is compared with the independently estimated recharge rate using BFLOW. The hydrologic modelling results show that the annual average recharge rate should be estimated by a long-term continuous simulation with a distributed hydrologic modelling technique.
Journal Article
Chemical Investigation of Diketopiperazines and N-Phenethylacetamide Isolated from Aquimarina sp. MC085 and Their Effect on TGF-β-Induced Epithelial–Mesenchymal Transition
2021
Chemical investigations of Aquimarina sp. MC085, which suppressed TGF-β-induced epithelial–mesenchymal transition (EMT) in A549 human lung cancer cells, led to the isolation of compounds 1–3. Structural characterization using spectroscopic data analyses in combination with Marfey’s analysis revealed that they were two diketopiperazines [cyclo(l-Pro-l-Leu) (1) and cyclo(l-Pro-l-Ile) (2)] and one N-phenethylacetamide (3). Cyclo(l-Pro-l-Leu) (1) and N-phenethylactamide (3) inhibited the TGF-β/Smad pathway and suppressed the metastasis of A549 cells by affecting TGF-β-induced EMT. However, cyclo(l-Pro-l-Ile) (2) downregulated mesenchymal factors via a non-Smad-mediated signaling pathway.
Journal Article
Development of the Korean framework for senior-friendly hospitals: a Delphi study
2017
Background
Aging is an inevitable part of life. One can maintain well-being and wellness even after discharge and/or transition if his or her functional decline is minimized, sudden decline is prevented, and functioning is promoted during hospitalization. Caring appropriately for elderly patients requires the systematic application of Senior-Friendly Hospital principles to all operating systems, including medical centres’ organization and environment, as well as patient treatment processes. The Senior-Friendly Hospital framework is valid and important for patient safety and quality improvement. This study aimed to make recommendations regarding the development of the Korean Framework for Senior-Friendly Hospitals for older patients’ care management, patient safety interventions, and health promotion, via a Delphi survey.
Methods
Two rounds of Delphi surveying were conducted with 15 participants who had at least 3 years’ experience in accreditation surveying and medical accreditation standards, survey methods, and accreditation investigator education. In each round, we calculated statistics describing each standard’s validity and feasibility.
Results
The Korean Framework for Senior-Friendly Hospitals included 4 Chapters, 11 categories, and 67 standards through consensus of the Senior-Friendly Hospitals task force and experts’ peer review. After the two rounds of Delphi surveying, validity evaluation led to no changes in standards of the Senior-Friendly Hospitals; however, the number of standards showing adequate validity decreased from 67 to 58. Regarding feasibility, no changes were necessary in the standards; however, the number of categories showing adequate feasibility decreased from 11 to 8 and from 67 to 30, respectively. The excluded categories were 3.2, 4.2, and 4.3 (service, transportation, and signage and identification). The highest feasibility values were given to standards 2.1.1, 4.1.4, and 4.1.6. The highest feasibility score was given to standard 2.4.2.
Conclusions
The Korean Framework for Senior-Friendly Hospitals needs to include 4 Chapters, 8 categories, and 30 standards. The Accreditation Program for Healthcare Organizations should include Senior-Friendly Hospitals -relevant standards considering Korea’s medical environment.
Journal Article
A study on the characteristics of the excavated pottery in Hanseong and Sabi periods of the Baekje Kingdom (South Korea): mineralogical, chemical and spectroscopic analysis
2024
The study analyzes the black color factors of black-burnished pottery excavated from the Pungnap Fortress and the Seokchon Tomb during the Hanseong period of the Baekje Kingdom. The current hypothesis surrounding the pottery’s black color factors suggests the use of magnetite, manganese oxide, and carbon. To compare the results of the black pottery, red pottery was used as the control group. To identify these black color factors, each hypothesis was investigated using several spectroscopic techniques. However, it was difficult to detect sufficient magnetite and manganese oxide on the surface of the black pottery to account for its black color. In contrast, a larger amount of carbon was located on the surface and core of the black pottery compared to the red pottery. These results indicate that the black factors can be credibly attributed to carbon rather than to magnetite or manganese oxide. The firing temperature of the black-burnished pottery was estimated from the mineral composition based on X-ray diffraction, and the firing atmosphere was deduced from the redox conditions based on the reduction index from Mössbauer spectroscopy. In addition, seven pieces of pottery excavated from Gunsu-ri Temple Site and Buyeo Ancient Tomb from the Sabi period of Baekje were investigated and compared the five pieces of pottery from the Hanseong period. Although the results were based on a limited number of potteries, various firing temperatures and redox atmosphere for pottery from the Hanseong and Sabi periods were carefully proposed.
Journal Article