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Evenly transferred single-layered graphene membrane assisted by strong substrate adhesion
Park, Seongjae,Kim, Hoijoon,Seol, Daehee,Park, Taejin,Leem, Mirine,Ha, Hyunwoo,An, Hyesung,You Kim, Hyun,Jeong, Seong-Jun,Park, Seongjun,Kim, Hyoungsub,Kim, Yunseok IOP 2017 Nanotechnology Vol.28 No.14
<P>We explored the transfer of a single-layered graphene membrane assisted by substrate adhesion. A relatively larger adhesion force was measured on the SiO<SUB>2</SUB> substrate compared with its van der Waals contribution, which is expected to result from the additional contribution of the chemical bonding force. Density functional theory calculations verified that the strong adhesion force was indeed accompanied by chemical bonding. The transfer of single-layered graphene and subsequent deposition of the dielectric layer were best performed on the SiO<SUB>2</SUB> substrate exhibiting a larger adhesion force. This study suggests the selection and/or modification of the underlying substrate for proper transfer of graphene as well as other 2D materials similar to graphene.</P>
Suppurative Meckel Diiverticulum in a 3-Year-Old Girl Presenting with Periumbilical Cellulitis
Park, Ji Sook,Lim, Chun Woo,Park, Taejin,Cho, Jae-Min,Seo, Ji-Hyun,Youn, Hee-Shang The Korean Society of Pediatric Gastroenterology 2015 Pediatric gastroenterology, hepatology & nutrition Vol.18 No.1
Meckel diverticulum (MD) is one of the most common congenital gastrointestinal anomalies and occurs in 1.2-2% of the general population. MD usually presents with massive painless rectal bleeding, intestinal obstruction or inflammation in children and adults. Suppurative Meckel diverticulitis is uncommon in children. An experience is described of a 3-year-old girl with suppurative inflammation in a tip of MD. She complained of acute colicky abdominal pain, vomiting and periumbilical erythema. Laparoscopic surgery found a relatively long MD with necrotic and fluid-filled cystic end, which was attatched to abdominal wall caused by inflammation. Herein, we report an interesting and unusual case of a suppurative Meckel diverticulitis presenting as periumbilical cellulitis in a child. Because of its varied presentations, MD might always be considered as one of the differential diagonosis.
Overexpression of Neuron-Specific Enolase as a Prognostic Factor in Patients with Gastric Cancer
Park, Taejin,Lee, Young-Joon,Jeong, Sang-Ho,Choi, Sang-Kyung,Jung, Eun-Jung,Ju, Young-tae,Jeong, Chi-Young,Park, Miyeong,Hah, Young-Sool,Yoo, Jiyun,Ha, Woo-Song,Hong, Soon-Chan,Ko, Gyung Hyuck The Korean Gastric Cancer Association 2017 Journal of gastric cancer Vol.17 No.3
Purpose: Enolase is a cytoplasmic enzyme that catalyzes the conversion of 2-phosphoglycerate to phosphoenolpyruvate in the glycolytic pathway. The aim of this study was to investigate whether the overexpression of neuron-specific enolase (NSE) can serve as a prognostic factor in patients with gastric cancer (GC). Materials and Methods: To assess its prognostic value in GC, NSE expression was measured by immunohistochemistry in a clinically annotated tissue microarray comprising of 327 human GC specimens. Cytoplasmic NSE expression was scored from 0 to 4, reflecting the percentage of NSE-positive cells. Results: In terms of histology as per the World Health Organization criteria (P=0.34), there were no differences between the NSE overexpression (NSE-OE) and NSE underexpression (NSE-UE) groups. The NSE-OE group showed a significantly lower rate of advanced GC (P<0.01), lymph node metastasis (P=0.01), advanced stage group (P<0.01), cancer-related death (P<0.01), and cancer recurrence (P<0.01). Additionally, a Kaplan-Meier survival analysis revealed that the NSE-OE group had longer cumulative survival times than the NSE-UE group (log-rank test, P<0.01). However, there were no significant differences in the serum levels of NSE expression in patients with GC and healthy volunteers (P=0.28). Conclusions: Patients with NSE overexpressing GC tissues showed better prognostic results, implying that NSE could be a candidate biomarker of GC.
Park, Taejin,Leem, Mirine,Lee, Hyangsook,Ahn, Wonsik,Kim, Hoijoon,Kim, Jinbum,Lee, Eunha,Kim, Yong-Hoon,Kim, Hyoungsub American Chemical Society 2017 JOURNAL OF PHYSICAL CHEMISTRY C - Vol.121 No.49
<P>Vertical MoO<SUB>2</SUB>/MoS<SUB>2</SUB> core–shell structures were synthesized on an amorphous surface (SiO<SUB>2</SUB>) by chemical vapor deposition at a high heating rate using a configuration in which the vapor phase was confined. The confined reaction configuration was achieved by partially covering the MoO<SUB>3</SUB>-containing boat with a substrate, which allowed rapid buildup of the partially reduced MoO<SUB>3–<I>x</I></SUB> crystals in an early stage (below 680 °C). Rapid temperature ramping to 780 °C enabled spontaneous transition of the reaction environment from sulfur-poor to sulfur-rich, which induced a sequential phase transition from MoO<SUB>3–<I>x</I></SUB> to intermediate MoO<SUB>2</SUB> and finally to MoO<SUB>2</SUB>/MoS<SUB>2</SUB> core–shell structures. The orthorhombic crystal structure of MoO<SUB>3–<I>x</I></SUB> contributed to the formation of vertical crystals on the amorphous substrate, whereas the nonvolatility of the subsequently formed MoO<SUB>2</SUB> enabled layer-by-layer sulfurization to form MoS<SUB>2</SUB> on the oxide surface with minimal resublimation loss of MoO<SUB>2</SUB>. By adjustment of the sulfurization temperature and time, excellent control over the thickness of the MoS<SUB>2</SUB> shell was achieved through the proposed synthesis method.</P><P><B>Graphic Abstract</B> <IMG SRC='http://pubs.acs.org/appl/literatum/publisher/achs/journals/content/jpccck/2017/jpccck.2017.121.issue-49/acs.jpcc.7b08171/production/images/medium/jp-2017-08171h_0005.gif'></P><P><A href='http://pubs.acs.org/doi/suppl/10.1021/jp7b08171'>ACS Electronic Supporting Info</A></P>
Noise Robust Automatic Speech Recognition Scheme with Histogram of Oriented Gradient Features
Park, Taejin,Beack, SeungKwan,Lee, Taejin The Institute of Electronics and Information Engin 2014 IEIE Transactions on Smart Processing & Computing Vol.3 No.5
In this paper, we propose a novel technique for noise robust automatic speech recognition (ASR). The development of ASR techniques has made it possible to recognize isolated words with a near perfect word recognition rate. However, in a highly noisy environment, a distinct mismatch between the trained speech and the test data results in a significantly degraded word recognition rate (WRA). Unlike conventional ASR systems employing Mel-frequency cepstral coefficients (MFCCs) and a hidden Markov model (HMM), this study employ histogram of oriented gradient (HOG) features and a Support Vector Machine (SVM) to ASR tasks to overcome this problem. Our proposed ASR system is less vulnerable to external interference noise, and achieves a higher WRA compared to a conventional ASR system equipped with MFCCs and an HMM. The performance of our proposed ASR system was evaluated using a phonetically balanced word (PBW) set mixed with artificially added noise.
Wide dynamic range high-speed three-dimensional quantitative OCT angiography with a hybrid-beam scan
Park, Taejin,Jang, Sun-Joo,Han, Myounghee,Ryu, Sukyoung,Oh, Wang-Yuhl The Optical Society 2018 Optics letters Vol.43 No.10
<P>We demonstrate a novel hybrid-beam scanning-based quantitative optical coherence tomography angiography (OCTA) that provides high-speed wide dynamic range blood flow speed imaging. The hybrid-beam scanning scheme enables multiple OCTA image acquisitions with a wide range of multiple time intervals simultaneously providing wide dynamic range blood flow speed imaging independent of the blood vessel orientation, which was quantified over a speed range of 0.6 similar to 104 mm/s through the blood flow phantom experiments. A fully automated high-speed hybrid-beam scanning-based quantitative OCTA system demonstrates visualization of blood flow speeds in various vessels from the main arteries to capillaries in a 4 mm x 4 mm area (1024 A-lines x 512 B-scans) in vivo in 20 s, showing its potential as a useful imaging tool for various biomedical applications. (C) 2018 Optical Society of America</P>