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AUSM 풍상차분법을 이용한 고속 점성 유동장 해석에서 최적의 수치적 벽면 경계조건 도출에 관한 연구
김용년,전병우,김문상 한국 항공대학교 항공산업기술연구소 2001 航空宇宙産業技術硏究所 硏究誌 Vol.11 No.-
Navier-Stokes 방정식을 사용하여 점성 유동장을 해석할 때 해의 정확도 및 수렴성에 영향을 줄 수 있는 요인들에는 여러 가지가 있다. 그 중에서도 물체 벽면에 부과되는 벽면 경계조건은 가장 큰 요인들 중에 하나로서, 본 논문에서는 단열 조건 혹은 주어진 벽면 온도 조건 하에서 추가적으로 요구되는 여러 종류의 수치적 벽면 경계조건들에 대해서 고속으로 비행하는 1/4 원형 실린더 주위 및 20도의 쐐기 형상을 갖는 물체 주위의 유동장을 해석해 봄으로써 가장 바람직한 해석 결과를 보여주는 벽면 경계조건을 도출하였다. 본 연구를 위해서 유한체적법을 사용한 2차원 Navier-Stokes 프로그램을 개발하였으며 대류항은 AUSM 풍상차분법을, 확산항은 중심차분법을 사용하여 플럭스를 계산하였다. There are many factors to affect the numerical solution accuracy and stability in viscous flowfields analysis using the Navier-Stokes equations. Wall boundary condition imposed on the solid wall is one of the most important factors. In this paper, several different sets of numerical wall boundary conditions are investigated to figure out what is the most optimum numerical wall boundary condition set by analyzing the flowfields around a 1/4 circular cylinder and 20 degree wedge shape geometry in very high speed flow under adiabatic or fixed wall temperature condition. The optimum wall boundary condition is introduced by simulating a finite volume Navier-Stokes solver, which hires AUSM upwind scheme to calculate the convection fluxes and central scheme to calculate the diffusion fluxes.
Kim, Hye-Jin,Kwon, Sojung,Nam, Seo Hee,Jung, Jae Woo,Kang, Minkyung,Ryu, Jihye,Kim, Ji Eon,Cheong, Jin-Gyu,Cho, Chang Yun,Kim, Somi,Song, Dae-Geun,Kim, Yong-Nyun,Kim, Tai Young,Jung, Min-Kyo,Lee, Kyun The Federation of American Societies for Experimen 2017 The FASEB Journal Vol.31 No.4
<P>Membrane proteins sense extracellular cues and transduce intracellular signaling to coordinate directionality and speed during cellular migration. They are often localized to specific regions, as with lipid rafts or tetraspanin-enriched microdomains; however, the dynamic interactions of tetraspanins with diverse receptors within tetraspanin-enriched microdomains on cellular surfaces remain largely unexplored. Here, we investigated effects of tetraspan(in) TM4SF5 (transmembrane 4 L6 family member 5)-enriched microdomains (T5ERMs) on the directionality of cell migration. Physical association of TM4SF5 with epidermal growth factor receptor (EGFR) and integrin alpha 5 was visualized by live fluorescence cross-correlation spectroscopy and higher-resolution microscopy at the leading edge of migratory cells, presumably forming TM4SF5-enriched microdomains. Whereas TM4SF5 and EGFR colocalized at themigrating leading region more than at the rear, TM4SF5 and integrin a5 colocalized evenly throughout cells. Cholesterol depletion and disruption in TM4SF5 post-translational modifications, including N-glycosylation and palmitoylation, altered TM4SF5 interactions and cellular localization, which led to less cellular migration speed and directionality in 2-or 3-dimensional conditions. TM4SF5 controlled directional cell migration and invasion, and importantly, these TM4SF5 functions were dependent on cholesterol, TM4SF5 post-translational modifications, and EGFR and integrin alpha 5 activity. Altogether, we showed that TM4SF5 dynamically interacted with EGFR and integrin a5 in migratory cells to control directionality and invasion.-Kim, H.-J., Kwon, S., Nam, S. H., Jung, J. W., Kang, M., Ryu, J., Kim, J. E., Cheong, J.-G., Cho, C. Y., Kim, S., Song, D.-G., Kim, Y.-N., Kim, T. Y., Jung, M.-K., Lee, K.-M., Pack, C.-G., Lee, J. W. Dynamic and coordinated single-molecular interactions at TM4SF5-enriched microdomains guide invasive behaviors in 2-and 3-dimensional environments. FASEB J. 31, 1461-1481 (2017). www.fasebj.org</P>
Kim, Tae Nyun,Park, Man Sik,Lee, Seong Keon,Yang, Sae Jeong,Lee, Kwan Woo,Nam, Moonsuk,Nam, Moon Suk,Park, Yong Soo,Woo, Jeong-Taek,Woo, Jeong Taek,Kim, Young Seol,Baik, Sei Hyun Macmillan Press 2012 Endocrine Vol.42 No.3
<P>The purpose of this study is to examine the association of A1C with beta-cell dysfunction, insulin resistance, and cardiovascular risk factors in Koreans with the relatively high risk for the future development of diabetes. This cross-sectional study recruited subjects from the pre-diabetic cohort of the Korea National Diabetes Program. Among study subjects (n = 616) aged 21-77 years with a history of hyperglycemia (fasting plasma glucose (FPG) 5.5 mmol/mL), analyses were conducted on 504 participants (296 women, 208 men) except for subjects with FPG 7.0 mmol/L or 120-min post-challenge plasma glucose 11.1 mmol/L or A1C 6.5 %. For insulin sensitivity and β-cell function classified by the categories of A1C levels, ?Ins(30-0)/?Glu(30-0) was lower in the highest quartile group than other groups. Although there was no significant difference in HOMA-IR according to the A1C categories, even lowest A1C group ( 5.3 %) already included many subjects with abnormal glucose tolerance. A1C showed a significant association with hsCRP, number of metabolic syndrome (MetS) components and ?Ins(30-0)/?Glu(30-0) after adjusting for age, gender, BMI, and medications whereas HOMA-IR was insignificantly associated with A1C. Stepwise regression analysis for A1C showed that A1C is independently and negatively associated with ?Ins(30-0)/?Glu(30-0), and positively associated with hsCRP. Our study showed that higher A1C was associated with impaired early-phase insulin secretion, MetS, and low grade inflammation in Koreans with the relatively high risk for the future development of diabetes.</P>
Kim, Kyoung Won,Kim, Min Ju,Lee, Seung Soo,Kim, Hyoung Jung,Shin, Yong Moon,Kim, Pyo-Nyun,Lee, Moon-Gyu American Roentgen Ray Society, etc.] 2008 American Journal of Roentgenology Vol.190 No.4
<P>The purposes of this study were to illustrate the sonographic features of focal hepatic lesions with peritumoral sparing of fatty infiltration in patients with hepatic steatosis, to correlate the sonographic findings with CT and MRI findings, and to discuss the possible mechanisms.</P>
Kim, Seung Up,Kim, Do Young,Park, Jun Yong,Lee, Jin Ha,Ahn, Sang Hoon,Kim, Ja Kyung,Paik, Yong Han,Lee, Kwan Sik,Chon, Chae Yoon,Choi, Eun Hee,Song, Ki Jun,Park, Young Nyun,Han, Kwang-Hyub Lippincott WilliamsWilkins, Inc. 2010 JOURNAL OF CLINICAL GASTROENTEROLOGY Vol.44 No.1
GOAL: This study aimed to enhance the diagnostic accuracy by defining different cutoff liver stiffness measurement (LSM) values according to alanine aminotransferase (ALT) level and combining LSM with noninvasive models in patients with chronic hepatitis B (CHB). BACKGROUND: Several studies have indicated that ALT influences LSM using FibroScan. STUDY: The study prospectively enrolled 200 patients (143 men, mean age 45.4 y) between June 2007 and November 2008 who had been diagnosed with CHB and underwent both liver biopsy and LSM on the same day. RESULTS: The area under the receiver operating characteristic curves (AUROC) of LSM for predicting cirrhosis in patients with ALT ≤upper limit of normal (ULN) was higher than that of all patients or those with ALT >ULN and ≤2× ULN (AUROC=0.884 vs. 0.849 and 0.867). The cutoff LSM values for ≥F2, ≥F3, and F4 were 6.0, 7.5, and 10.1 kPa, respectively, in patients with ALT ≤ULN, whereas they were 8.9, 11.0, and 15.5 kPa, respectively, in those with ALT >ULN and ≤2× ULN. The combination of LSM and the age-spleen-platelet ratio index performed the best at predicting cirrhosis, regardless of ALT level (AUROC=0.917 in patients with ALT ≤ULN, 0.909 in those with ALT ≤2× ULN, and 0.894 in all patients). CONCLUSIONS: Different cutoff LSM values according to ALT level and combination with age-spleen-platelet ratio index can enhance the performance of LSM in CHB, regardless of ALT level.
Remifentanil Protects Human Keratinocyte Through Autophagic Expression
Kim, Eok Nyun,Park, Chang Hoon,Woo, Mi Na,Yoon, Ji Young,Park, Bong Soo,Kim, Yong Ho,Kim, Cheul Hong The Korean Dental Society of Anesthsiology 2014 Journal of Dental Anesthesia and Pain Medicine Vol.14 No.2
Background: Remifentanil, an ultra-short-acting mu-opioid receptor agonist, is unique from other opioids because of its esterase-based metabolism, minimal accumulation, and very rapid onset and offset of clinical action. Remifentanil can prevent the inflammatory response and can suppress inducible nitric oxide synthase expression in a septic mouse model. However, the effects of remifentanil on human keratinocyte and autophagy have yet to be fully elucidated during hypoxia-reoxygenation. Here we investigated whether remifentanil confers protective effect against hypoxia-reoxygenation in human keratinocyte and, if so, whether autophagy mediates this effect. Methods: The human keratinocytes were cultured under 1% oxygen tension. The cells were gassed with 94% $N_2$, and 5% $CO_2$ and incubated for 24 h at $37^{\circ}C$. To determine whether the administration of affects human keratinocytes hypoxia-reoxygenation injury, cells were then exposed to various concentrations of remifentanil (0.01, 0.1, 0.5 and 1 ng/ml) for 2 h. After remifentanil treatment, to simulate reoxygenation and recovery, the cells were reoxygenated for 12 h at $37^{\circ}C$. Control group did not receive remifentanil treatment. Normoxia group did not receive hypoxia and remifentanil treatment for 36 h. 3-MA group was treated 3-methyladenine (3-MA) for 1h before remifentanil treatment. Cell viability was measured using a quantitative colorimetric assay with MTT, showing the mitochondrial activity of living cells. Cells were stained with fluorescence and analyzed with Western blot analysis to find out any relations with activation of autophagy. Results: Prominent accumulation of autophagic specific staining MDC was observed around the nuclei in RPT group HaCaT cells. Similarly, AO staining, red fluorescent spots appeared in RPT group HaCaT cells, while the Normoxia, control and 3-MA groups showed mainly green cytoplasmic fluorescence. We here examined activation of autophagy related protein under H/R-induced cells by Western blotting analysis. Atg5, Beclin-1, LC3-II (microtubule-associated protein 1 light chain 3 form II) and p62 was elevated in RPT group cells. But they were decreased when autophagy was suppressed by 3-MA (Fig. 5). Conclusions: Although the findings of this study are limited to an in vitro interpretation, we suggest that remifentanil may have a beneficial effect in the recovery of wound from hypoxia-reoxygenation injury.