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Choi, Seung Ho,Kim, Sung June,Byun, Kyung Min The Optical Society 2009 Applied optics Vol.48 No.15
<P>A transmission-type surface plasmon resonance configuration with dielectric gratings regularly patterned on a silver film was investigated with the aim of enhancing the diffraction efficiency of radiative surface plasmons. The theoretical work was conducted using rigorous coupled-wave analysis in terms of first order diffraction efficiency and conversion efficiency (CE). The results show that pyramid gratings can produce a higher transmittance compared with other grating profiles. Design optimization of the pyramid grating at a wide range of grating thicknesses and periods resulted in a maximum transmittance that was larger than 77% and a peak CE of about 85%. This study demonstrates the potential of using transmitted surface plasmon waves in various optical devices, such as optical biosensors, optical imaging systems, and polarization filters.</P>
INTEGRAL REPRESENTATIONS FOR SRIVASTAVA'S HYPERGEOMETRIC FUNCTION H<sub>A</sub>
Choi, June-Sang,Hasanov, Anvar,Turaev, Mamasali The Honam Mathematical Society 2012 호남수학학술지 Vol.34 No.1
While investigating the Lauricella's list of 14 complete second-order hypergeometric series in three variables, Srivastava noticed the existence of three additional complete triple hypergeometric series of the second order, which were denoted by $H_A$, $H_B$ and $H_C$. Each of these three triple hypergeometric functions $H_A$, $H_B$ and $H_C$ has been investigated extensively in many different ways including, for example, in the problem of finding their integral representations of one kind or the other. Here, in this paper, we aim at presenting further integral representations for the Srivatava's triple hypergeometric function $H_A$.
( Sang Gyun Kim ),( Ho June Song ),( Il Ju Choi ),( Joo Young Cho ),( Hwoon Yong Jung ),( Bora Keum ),( Jae Hee Cheon ),( Yong Chan Lee ),( Jae Gyu Kim ),( Sue K. Park ),( Byung Joo Park ),( Hyun Chae 대한소화기기능성질환·운동학회 2010 Gut and Liver Vol.4 No.4
Background/Aims: Helicobacter pylori eradication may facilitate the healing of iatrogenic ulcer after endoscopic resection of gastric neoplasm. This study involved designing a randomized, double-blinded, placebo-controlled, multicenter trial, performed by the Korean College of Helicobacter and Upper Gastrointestinal Research and the Medical Research Collaboration Center, Seoul National University Hospital. Methods: We intend to enroll up to 232 patients H.-pylori-positive patients who have gastric adenoma or early gastric cancer after endoscopic resection. The enrolled patients are being randomly allocated to the H.-pylori-eradication-plus-proton-pump-inhibitor group or the placebo-plus-proton-pump-inhibitor group based on their histology results and the size of the resected specimen. After random allocation, the iatrogenic ulcer size and stage are evaluated at 4- and 8-week follow-ups (with a window of ±7 days). The primary end point is the healing rate of the ulcer by stage, and the secondary end point is the rate of ulcer size reduction, relief rate from ulcer-related symptoms, and adverse-event rates. Results: More than 90% of the target subjects have already been enrolled into the study and are receiving ongoing periodic monitoring by the Medical Research Collaboration Center. Conclusions: Completion of the study should reveal whether H. pylori eradication can facilitate the healing of ulcer after endoscopic resection in Korea. (Gut Liver 2010;4:514-517)
SEVERAL INTEGRAL REPRESENTATIONS INVOLVING TRIPLE HYPERGEOMETRIC FUNCTIONS
Choi, June-Sang,Hasanov, Anvar,Turaev, Mamasali The Honam Mathematical Society 2011 호남수학학술지 Vol.33 No.2
A (presumably) new class of generalized triple hyper-geometric functions is presented. We also give integral representations of Laplace type for certain special cases of the new class of functions.
Determinants of the Laplacians on the N-Dimensional Unit Sphere S(n) (n = 8; 9)
( June Sang Choi ) 호남수학회 2011 호남수학학술지 Vol.33 No.3
During the last three decades, the problem of evaluation of the determinants of the Laplacians on Riemann manifolds has received considerable attention by many authors. The functional determinant for the n-dimensional sphere S(n) with the standard metric has been computed in several ways. Here we aim at computing the determinants of the Laplacians on S(n) (n = 8, 9) by mainly using ceratin known closed-form evaluations of series involving Zeta function.
Application of the Operator H(α, β) to the Saran Function F(E) and Some Other Results
( June Sang Choi ),( Yong Sup Kim ),( Anvar Hasanov ) 호남수학회 2011 호남수학학술지 Vol.33 No.4
The enormous success of the theory of hypergeometric series in a single variable has stimulated the development of a corresponding theory in two and more variables. A wide variety of investigations in the theory of several variable hypergeometric functions have been essentially motivated by the fact that solutions of many applied problems involving partial differential equations are obtainable with the help of such hypergeometric functions. Here, in this trend, we aim at presenting further decomposition formulas for Saran function F(E), which are used to give some integral representations of the function F(E). We also present a system of partial differential equations for the Saran function F(E).
Choi, Hongyoon,Bang, Ji-In,Cheon, Gi Jeong,Kim, Yong Hwy,Park, Chul-Kee,Park, Sung-Hye,Kang, Keon Wook,Chung, June-Key,Kim, Euishin E.,Lee, Dong Soo Wolters Kluwer Health | Lippincott Williams Wilkin 2015 Nuclear medicine communications Vol.36 No.3
INTRODUCTION: Methylation status of the methyl-guanine methyltransferase (MGMT) promoter is associated with a favorable response to a DNA alkylating agent in high-grade gliomas. We analyzed PET scans of patients with high-grade gliomas to determine whether the MGMT methylation status affects the tumor metabolic characteristics. PATIENTS AND METHODS: Twenty-three patients with high-grade glioma, who were initially examined with C-methionine (MET) and F-fluorodeoxyglucose (FDG) PET, were retrospectively enrolled. MET and FDG PET images were coregistered to each other and quantitative uptake of MET or FDG was assessed using tumor-to-normal uptake ratio of the cortex (TNR). TNRs for MET and FDG PET were compared between the two groups classified by MGMT promoter methylation status. RESULTS: Maximum TNRFDG of the MGMT methylated group was significantly higher than that of the MGMT unmethylated group (1.80±0.90 vs. 1.29±0.19; P=0.02). The MGMT methylated group also showed a trend for increased mean TNRFDG compared with the unmethylated group (0.85±0.21 vs. 0.72±0.11; P=0.10). There was no significant difference in TNRMET between the groups. In subgroup analyses with WHO grade 3 and 4, a trend for higher maximum TNRFDG was found in the MGMT methylated group compared with the unmethylated group. CONCLUSION: The MGMT methylated group showed higher glucose metabolism compared with the unmethylated group, whereas MET uptake did not show a significant difference. This suggests that MGMT methylation in high-grade gliomas could affect the tumor glucose metabolism. Thus, MGMT methylation status can cause a discrepancy in the prognostic prediction of high-grade gliomas by FDG PET, especially in patients scheduled for DNA alkylating chemotherapeutics.
Choi, Hongyoon,Phi, Ji Hoon,Paeng, Jin Chul,Kim, Seung-Ki,Lee, Yun-Sang,Jeong, Jae Min,Chung, June-Key,Lee, Dong Soo,Wang, Kyu-Chang MIT Press 2013 Molecular imaging Vol.12 No.4
<P>Enhanced expression of integrin αvβ3 is commonly used as a biomarker for angiogenesis, which is one of the key pathophysiologic processes in cerebral infarct. Integrin αvβ3 can be imaged with arginine-glycine-aspartic acid (RGD) peptide agents. In this study, characteristics of positron emission tomography (PET) using a 68Ga-labeled RGD were investigated in pediatric cerebral infarct. Pediatric patients with moyamoya disease underwent 68Ga-RGD PET in a research protocol for neovascularization evaluation. In these patients, 17 cerebral infarct lesions of 10 patients were included in the analysis. On 68Ga-RGD PET, the infarct lesion to contralateral brain ratio (LCR) of the infarct lesion was measured and analyzed with regard to postinfarct time interval (PTI) and perfusion single-photon emission computed tomography (SPECT) findings. An increase in 68Ga-RGD uptake was observed in cerebral infarct, particularly in recent lesions. The LCR was significantly higher in the recent than in the chronic lesions, and a significant correlation existed between the LCR and PTI. Additionally, the LCR was significantly higher in the lesions with hyperperfusion on SPECT. This study, as the first human study using an RGD agent for in vivo cerebral infarct imaging, demonstrated that 68Ga-RGD PET has a potential for molecular imaging of integrin αvβ3 expression in cerebral infarct as a biomarker of angiogenesis.</P>
( June Hong Kim ),( Jae Hoon Choi ),( Hyun Kook Lee ),( Woo Hyung Bae ),( Kook Jin Chun ),( Yun Seong Kim ),( Sang Kwon Lee ),( Hyung Hoi Kim ),( Taek Jong Hong ),( Yong Woo Shin ) 대한내과학회 2008 The Korean Journal of Internal Medicine Vol.23 No.3
Background/Aims: We examined the ischemia-modified albumin (IMA) level during exercise in patients with coronary artery disease (CAD). Methods: Forty patients with a history of chest pain underwent both symptom-limited treadmill exercise stress testing and coronary angiography within one week. During the treadmill tests, blood samples were obtained at baseline and 5 min after exercise to measure the serum IMA level. Results: Of the 40 patients, fourteen (35%, CAD group) had significant coronary artery stenosis, while the other 26 (65%, non-CAD group) did not. The baseline and post-exercise IMA levels in the two groups did not differ significantly (105.2±7.2 vs. 107.7±6.7 U/mL at baseline and 93.1±10.1 vs. 94.8±5.7 U/mL at post-exercise in the CAD and non-CAD groups, p=0.29 and 0.57, respectively). The changes in IMA after exercise did not differ either (-10.4±7.5 vs. -14.0±7.6 U/mL in the CAD and non-CAD groups, respectively, p=0.10). Similarly, the change in IMA between the exercise ECG test positive (TMT positive, n=9) and negative (TMT negative, n=20) groups did not differ (-14.63±5.19, vs -8.50±9.01 U/mL, p=0.15, in the TMT positive and negative groups, respectively). Conclusions: Our results suggest that IMA has limitation in detecting myocardial ischemia during symptom-limited exercise stress tests.
Choi, Yeon Sik,Sung, Jinwoo,Kang, Seok Ju,Cho, Sung Hwan,Hwang, Ihn,Hwang, Sun Kak,Huh, June,Kim, Ho‐,Cheol,Bauer, Siegfried,Park, Cheolmin WILEY‐VCH Verlag 2013 Advanced functional materials Vol.23 No.9
<P><B>Abstract</B></P><P>Films made of 2D networks of single‐walled carbon nanotubes (SWNTs) are one of the most promising active‐channel materials for field‐effect transistors (FETs) and have a variety of flexible electronic applications, ranging from biological and chemical sensors to high‐speed switching devices. Challenges, however, still remain due to the current hysteresis of SWNT‐containing FETs, which has hindered further development. A new and robust method to control the current hysteresis of a SWNT‐network FET is presented, which involves the non‐volatile polarization of a ferroelectric poly(vinylidene fluoride‐trifluoroethylene) (P(VDF‐TrFE)) gate insulator. A top‐gate FET with a solution‐processed SWNT‐network exhibits significant suppression of the hysteresis when the gate‐voltage sweep is greater than the coercive field of the ferroelectric polymer layer (≈50 MV m<SUP>−1</SUP>). These near‐hysteresis‐free characteristics are believed to be due to the characteristic hysteresis of the P(VDF‐TrFE), resulting from its non‐volatile polarization, which makes effective compensation for the current hysteresis of the SWNT‐network FETs. The onset voltage for hysteresis‐minimized operation is able to be tuned simply by controlling the thickness of the ferroelectric film, which opens the possibility of operating hysteresis‐free devices with gate voltages down to a few volts.</P>