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203 results on '"Lee, Youngeun"'

10. Ultra‐strong and biodegradable nanocomposite fibers of poly(butylene adipate‐co‐terephthalate)/cellulose nanocrystal prepared by dry‐jet wet spinning.

Author

Lee, Youngeun, Kim, Min Woo, Kim, Hyo Jeong, Kim, Jin Kyung, Won, Tae Kyung, Miyawaki, Jin, Chae, Han Gi, and Eom, Youngho

Subjects
*CELLULOSE nanocrystals, *NYLON fibers, *CHEMICAL affinity, *FIBERS, *BUTENE, *NANOCOMPOSITE materials, *CELLULOSE, *POLYESTER fibers
Abstract

Fiber‐based products constitute a significant portion of plastic waste and cause environmental damage. In particular, discarded sanitary masks and fishing gear disintegrate into microfiber plastics, posing a significant threat to human health and ecosystems. In this study, we developed robust biodegradable nanocomposite fibers of poly(butylene adipate‐co‐terephthalate) (PBAT)/cellulose nanocrystals (CNCs) (1 and 2 wt%) through dry‐jet wet spinning, by using dimethyl sulfoxide (DMSO) as a common solvent. The control PBAT fibers exhibit remarkable mechanical performance with tensile strength and toughness of 160.0 MPa and 43.0 MJ m−3, respectively. CNC addition has a toughening effect with slightly reduced strength but enhanced toughness (148.8 MPa and 69.0 MJ m−3, respectively, for 2 wt% CNC); their mechanical performances are superior to those of previously reported PBAT‐based materials. The remarkable performance of the fibers is attributed to a highly oriented structure with a total draw ratio of 15 after post‐hot drawing. The control and nanocomposite fibers exhibit spot‐like patterns in 2D wide‐angle x‐ray diffraction patterns with Herman's orientation factor of 0.54–0.58. The theoretical Hansen solubility parameter confirmed the poor chemical affinity between the PBAT and CNC. Nonetheless, the rheological characterization revealed that well‐dispersed CNCs with DMSO produced a physical network in the PBAT matrix, resulting in the toughening effect. Such robust nanocomposite fibers consisting of fully biodegradable components are promising alternatives to nondegradable nylon and polyester fibers. Highlights: Robust biodegradable nanocomposite fibers of PBAT and CNC are prepared.Nanocomposite fibers are dry‐jet wet spun using DMSO as a common solvent.PBAT fibers exhibit strength and toughness of 160.0 MPa and 43.0 MJ m−3.2 wt% CNC toughens the PBAT fibers with an enhanced toughness of 69.0 MJ m−3.Rheological results confirm the toughening effect of well‐dispersed CNC in PBAT. [ABSTRACT FROM AUTHOR]

Published
2024
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13. PolyDepth: Real-time Penetration Depth Computation using Iterative Contact-Space Projection

Author

Je, Changsoo, Tang, Min, Lee, Youngeun, Lee, Minkyoung, and Kim, Young J.

Subjects
Computer Science - Graphics, Computer Science - Computational Geometry, Computer Science - Robotics, I.2.9, I.3.5, I.3.7, I.6.8
Abstract

We present a real-time algorithm that finds the Penetration Depth (PD) between general polygonal models based on iterative and local optimization techniques. Given an in-collision configuration of an object in configuration space, we find an initial collision-free configuration using several methods such as centroid difference, maximally clear configuration, motion coherence, random configuration, and sampling-based search. We project this configuration on to a local contact space using a variant of continuous collision detection algorithm and construct a linear convex cone around the projected configuration. We then formulate a new projection of the in-collision configuration onto the convex cone as a Linear Complementarity Problem (LCP), which we solve using a type of Gauss-Seidel iterative algorithm. We repeat this procedure until a locally optimal PD is obtained. Our algorithm can process complicated models consisting of tens of thousands triangles at interactive rates., Comment: Presented in ACM SIGGRAPH 2012. 15 pages, 23 figures

Published
2015
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25. Mobile BCI dataset of scalp- and ear-EEGs with ERP and SSVEP paradigms while standing, walking, and running

Author

Lee, Youngeun

Abstract

A mobile dataset obtained from electroencephalography (EEG) of the scalp and around the ear as well as from locomotion sensors by 24 participants moving at four different speeds while performing two brain-computer interface (BCI) tasks. The data were collected from 32-channel scalp-EEG, 14-channel ear-EEG, 4-channel electrooculography, and 9-channel inertial measurement units placed at the forehead, left ankle, and right ankle.

Published
2022
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32. Lymph node fibroblastic reticular cells regulate differentiation and function of CD4 T cells via CD25

Author

Kim, Dongeon, primary, Kim, Mingyo, additional, Kim, Tae Woo, additional, Choe, Yong-ho, additional, Noh, Hae Sook, additional, Jeon, Hyun Min, additional, Kim, HyunSeok, additional, Lee, Youngeun, additional, Hur, Gayeong, additional, Lee, Kyung-Mi, additional, Shin, Kihyuk, additional, Lee, Sang-il, additional, and Lee, Seung-Hyo, additional

Published
2022
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35. Cytomorphological Features of Hyperchromatic Crowded Groups in Liquid-Based Cervicovaginal Cytology: A Single Institutional Experience

Author

Lee, Youngeun, Lee, Cheol, Park, In Ae, An, Hyoung Jin, and Kim, Haeryoung

Subjects
0301 basic medicine, Pathology, medicine.medical_specialty, Histology, Population, Pathology and Forensic Medicine, 03 medical and health sciences, 0302 clinical medicine, Cytology, medicine, lcsh:Pathology, Outpatient clinic, liquid-based cytology, education, hyperchromatic crowded groups, education.field_of_study, business.industry, Cervicovaginal cytology, medicine.disease, cervical neoplasms, Squamous intraepithelial lesion, 030104 developmental biology, 030220 oncology & carcinogenesis, Liquid-based cytology, Adenocarcinoma, Liquid based, Original Article, business, lcsh:RB1-214
Abstract

Background Hyperchromatic crowed groups (HCGs) are defined as three-dimensional aggregates of crowded cells with hyperchromatic nuclei, and are frequently encountered in cervicovaginal liquid-based cytology (LBC). Here, we aimed to examine the prevalence of HCGs in cervicovaginal LBC and the cytomorphological characteristics of various epithelial cell clusters presenting as HCGs. Methods We first examined the prevalence of HCGs in a "routine cohort" of LBC cytology (n=331), consisting of all cervicovaginal LBCs accessioned over 3 days from outpatient clinics (n=179) and the screening population (n=152). Then we examined a second "high-grade epithelial cell abnormalities (H-ECA) cohort" (n=69) of LBCs diagnosed as high-grade squamous intraepithelial lesion (HSIL), squamous cell carcinoma (SCC), or adenocarcinoma during 1 year. Results HCGs was observed in 34.4% of the routine cohort and were significantly more frequent in the epithelial cell abnormality category compared to the non-neoplastic category (p=.003). The majority of HCGs represented atrophy (70%). Of the 69 histologically confirmed H-ECA cases, all contained HCGs. The majority of cases were HSIL (62%), followed by SCC (16%). Individually scattered neoplastic cells outside the HCGs were significantly more frequent in SCCs compared to glandular neoplasia (p=.002). Despite the obscuring thick nature of the HCGs, examining the edges and the different focal planes of the HCGs and the background were helpful in defining the nature of the HCGs. Conclusions HCGs were frequently observed in cervicovaginal LBC and were mostly non-neoplastic; however, neoplastic HCGs were mostly high-grade lesions. Being aware of the cytomorphological features of different HCGs is important in order to avoid potential false-negative cytology interpretation.

Published
2019

44. Liquid-Based Cytology Features of Papillary Squamotransitional Cell Carcinoma of the Uterine Cervix

Author

Lee, Yangkyu, Choi, Younghwa, Lee, Kiryang, Lee, Youngeun, Kim, Hyojin, Choe, Ji-Young, Lee, Hye Seung, Kim, Yong Beom, and Kim, Haeryoung

Subjects
Pathology, medicine.medical_specialty, Histology, business.industry, Brief Case Report, Pathology and Forensic Medicine, Uterine cervix, Text mining, Liquid-based cytology, lcsh:Pathology, Medicine, Basal cell, business, lcsh:RB1-214
Published
2019

46. A theoretical study on tunneling based biosensor having a redox-active monolayer using physics based simulation.

Author

Kim, Kyoung Yeon, Lee, Won Cheol, Yun, Jun Yeon, Lee, Youngeun, Choi, Seoungwook, Jin, Seonghoon, and Park, Young June

Subjects
BIOSENSORS, OXIDATION-reduction reaction, COMPUTER simulation, GREEN'S functions, ELECTRON tunneling, HEAT equation
Abstract

We developed a numerical simulator to model the operation of a tunneling based biosensor which has a redox-active monolayer. The simulator takes a realistic device structure as a simulation domain, and it employs the drift-diffusion equation for ion transport, the non-equilibrium Green's function formalism for electron tunneling, and the Ramo-Shockley theorem for accurate calculation of non-faradaic current. We also accounted for the buffer reaction and the immobilized peptide layer. For efficient transient simulation, the implicit time integration scheme is employed where the solution at each time step is obtained from the coupled Newton-Raphson method. As an application, we studied the operation of a recently fabricated reference-electrode free biosensor in various bias conditions and confirmed the effect of buffer reaction and the current flowing mechanism. Using the simulator, we also found a strategy to maximize the sensitivity of the tunneling based sensor. [ABSTRACT FROM AUTHOR]

Published
2018
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47. Longitudinal Study on Deterrent Effect of Drug-Induced Homicide Law on Opioid-Related Mortality Across 92 Counties and the District of Columbia in the U.S.

Author

Lee, Youngeun, Choi, Sung W., and Lee, Jonathan

Subjects
*DRUG side effects, *HOMICIDE, *LONGITUDINAL method, *OPIOID epidemic, *MORTALITY
Abstract

In response to the opioid epidemic in the United States, the federal and state governments have initiated various public health responses to mitigate the problem. Among others, Drug-Induced Homicide Laws (DIHL) have been introduced to disrupt opioid supply by imposing unconventionally punitive sanctions against sales and distribution. The purpose of this study was to examine whether DIHL had an impact on opioid-related deaths, while controlling for other laws and socioeconomic indices. A dynamic panel model was used with cases from 92 counties across 10 states and the District of Columbia between 2013 and 2018. The findings suggest that DIHL implementation has curtailed the rate of opioid mortality. Supply-interruption approaches may have merits and should be further evaluated. [ABSTRACT FROM AUTHOR]

Published
2022
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48. GABAergic-like dopamine synapses in the brain

Author

Kim, Jae-Ick, primary, Kim, Hyun-Jin, additional, Hwang, Byungjae, additional, Reva, Maria, additional, Lee, Jieun, additional, Lee, Byeong Eun, additional, Lee, Youngeun, additional, Myung, Kyungjae, additional, Baik, Ja-Hyun, additional, and Park, Jung-Hoon, additional

Published
2021
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