Relationship Between Fluid Flow Stability and Submerged Entry Nozzle Port Angle in a Conventional Slab Continuous-Casting Mold

Won‑hyuk Lee,Kyung‑woo Yi 대한금속·재료학회 2021 METALS AND MATERIALS International Vol.27 No.10

Fluid flow patterns within a conventional slab continuous-casting mold are closely linked to the port angle of the submergedentry nozzle (SEN). Fluid flow is unstable below a certain port angle, with large fluctuations near the port outlet as wellas jet stream oscillation and repeated vortex formation and dissipation within the mold. However, such phenomena are notobserved above a certain port angle, at which the flow pattern becomes stable. This behavior was investigated via bothnumerical simulation and water model experimentation; two different regions were identified with flow patterns varyingaccording to the SEN port angle. In addition, a close quantitative relationship was identified between changes in the portangle and fluid velocity variations. For SEN port angles in the range 0°–15°, the flow velocity in the upper circulation zoneoscillated in an unstable manner. For port angles of 20° or more, the flow velocity of the same zone decreased significantlyand stabilized. When the gas was injected, the unstable region elongated to 0°–20°. The present study offers insight towarddeveloping a clearer understanding of the complex flow patterns in casting molds, as well as of the conditions necessary forstable flow patterns.

한라산 주변에 발생하는 Karman Vortex Street 재현

권지혁(Kwon Ji-hyuk·Lee),이연원(Lee Yeon-won),김영덕(Kim Young-duk),박광열(Park Kwang-yul) 한국풍공학회 2006 한국풍공학회지 Vol.10 No.1

늦가을과 초본 사이 제주도 후면에 Karman vortex street가 발생한다. 이러한 vortex가 발생하기 위해서는 기온 역전층과 5 ~ 13 m/s의 지속적인 바람이 필요하다는 것을 밝히기 위한 많은 연구들이 있었다. 이러한 vortex clouds는 발생 후 주 풍향의 방향을 이동하게 된다. Karman vortex street는 기상학에서 매우 흥미로운 주제이다. 본 연구에서는 LES 난류 모델을 이용하여 Karman vortex street에 관한 해석을 수행하고 수치해석을 통해 얻은 결과와 기상 데이터가 일치함을 보였다. From late autumn to the beginning of the spring, the phenomena of the Karman vortex street have been frequently observed in the wake of Mt. Halla in the Jeju island. Some researches revealed that the necessary conditions for development of these vortex clouds are a strong low-level inversion of temperature and a persistent wind speed of 5 to 13m/s. After the cloud is formed, the vortex clouds are shed from alternating sides of Jeju island and then move downwind with main airflow stream. The Karman vortex street in the wake of the Jeju island was one of the interesting topics in meteorology. In this study, CFD using LES turbulence model was developed to investigate the Karman vortex street and the results of CFD showed a good agreement with weather data.

The Potency of Abamectin Formulations against the Pine Wood Nematode, Bursaphelenchus xylophilus

Jong-won Lee(Jong-won Lee),Abraham Okki Mwamula(Abraham Okki Mwamula ),Jae-hyuk Choi(Jae-hyuk Choi),Ho-wook Lee(Ho-wook Lee),Yi Seul Kim(Yi Seul Kim),Jin-Hyo Kim(Jin-Hyo Kim),Dong Woon Lee(Dong Woon L 한국식물병리학회 2023 Plant Pathology Journal Vol.39 No.3

Abamectin offers great protection against Bursaphelenchus xylophilus, a well-known devastating pathogen of pine tree stands. Trunk injection of nematicides is currently the most preferred method of control. This study aimed to evaluate the potency of the commonly used formulations of abamectin against B. xylophilus. Twenty-one formulations of abamectin were evaluated by comparing their sublethal toxicities and reproduction inhibition potentials against B. xylophilus. Nematodes were treated with diluted formulation concentrations in multi-well culture plates. And, populations pre-exposed to pre-determined concentrations of the formulations were inoculated onto Botrytis cinerea culture, and in pine twig cuttings. Potency was contrastingly different among formulations, with LC95 of 0.00285 and 0.39462 mg/ml for the most, and the least potent formulation, respectively. Paralysis generally occurred at an application dose of 0.06 μg/ ml or higher, and formulations with high sublethal toxicities caused significant paralysis levels at the tested doses, albeit the variations. Nematode reproduction was evident at lower doses of 0.00053-0.0006 μg/ml both on Botrytis cinerea and pine twigs, with significant variations among formulations. Thus, the study highlighted the inconsistencies in the potency of similar product formulations with the same active ingredient concentration against the target organism, and the need to analyze the potential antagonistic effects of the addi-tives used in formulations.

Shh signaling is essential for rugae morphogenesis in mice.

Lee, Jong-Min,Miyazawa, Seita,Shin, Jeong-Oh,Kwon, Hyuk-Jae,Kang, Dae-Woon,Choi, Byung-Jai,Lee, Jae-Ho,Kondo, Shigeru,Cho, Sung-Won,Jung, Han-Sung Springer 2011 Histochemistry and cell biology Vol.136 No.6

<P>Palatal ridges, or rugae palatinae, are corrugated structures observed in the hard palate region. They are found in most mammalian species, but their number and arrangement are species-specific. Nine palatal rugae are found in the mouse secondary palate. Previous studies have shown that epithelial Shh signaling in the palatal ridge plays an important role during rugae development. Moreover, Wnt family members, including LEF1, play a functional role in orofacial morphogenesis. To explore the function of Shh during rugae development, we utilized the maternal transfer of 5E1 (anti-Shh antibody) to mouse embryos. 5E1 induced abnormal rugae patterning characterized by a spotted shape of palatal ridge rather than a stripe. The expression patterns of Shh and Shh-related genes, Sostdc1, Lef1 and Ptch1, were disrupted following 5E1 injection. Moreover, rugae-specific cell proliferation and inter-rugae-specific apoptosis were affected by inhibition of Shh signaling. We hypothesize that the altered gene expression patterns and the change in molecular events caused by the inhibition of Shh signaling may have induced abnormal rugae patterning. Furthermore, we propose a reaction-diffusion model generated by Wnt, Shh and Sostdc1 signaling. In this study, we show that Sostdc1, a secreted inhibitor of the Wnt pathway, is a downstream target of Shh and hypothesize that the interaction of Wnt, Shh and Sostdc1 is a pivotal mechanism controlling the spatial patterning of palatal rugae.</P>

Grain size effects on the dielectric properties of CaCu3Ti4O12 ceramics for supercapacitor applications

Lee, Ji-Won,Koh, Jung-Hyuk Elsevier Science B.V., Amsterdam. 2015 Ceramics international Vol.41 No.-

NOISE CHARACTERISTICS OF LINEAR COMPRESSOR FOR REFRIGERATORS

Hyuk Lee,Sunghyun Ki,Jung-Hwan Kang,Seung-Man Yang,Won-hag Rhee 한국소음진동공학회 2008 한국소음진동공학회 국제학술대회논문집 Vol.2008 No.7

Herpesvirus-associated Ubiquitin-specific Protease (HAUSP) Modulates Peroxisome Proliferator-activated Receptor γ (PPARγ) Stability through Its Deubiquitinating Activity

Lee, Kyeong Won,Cho, Jin Gu,Kim, Chul Min,Kang, A Young,Kim, Min,Ahn, Byung Yong,Chung, Sung Soo,Lim, Key-Hwan,Baek, Kwang-Hyun,Sung, Jong-Hyuk,Park, Kyong Soo,Park, Sang Gyu American Society for Biochemistry and Molecular Bi 2013 The Journal of biological chemistry Vol.288 No.46

<P>The peroxisome proliferator-activated receptor γ (PPARγ) is a central regulator of adipogenesis and modulates glucose and lipid metabolism. In this study, herpesvirus-associated ubiquitin-specific protease (HAUSP) was isolated as a binding partner of PPARγ. Both endogenous and exogenous PPARγ associated with HAUSP in co-immunoprecipitation analysis. HAUSP, but not the catalytically inactive HAUSP C223S mutant, increased the stability of both endogenous and exogenous PPARγ through its deubiquitinating activity. Site-directed mutagenesis experiments showed that the Lys<SUP>462</SUP> residue of PPARγ is critical for ubiquitination. HBX 41,108, a specific inhibitor of HAUSP, abolished the increase in PPARγ stability induced by HAUSP. In addition, knockdown of endogenous HAUSP using siRNA decreased PPARγ protein levels. HAUSP enhanced the transcriptional activity of both exogenous and endogenous PPARγ in luciferase activity assays. Quantitative RT-PCR analysis showed that HAUSP increased the transcript levels of PPARγ target genes in HepG2 cells, resulting in the enhanced uptake of glucose and fatty acids, and vice versa, upon siRNA knockdown of HAUSP. <I>In vivo</I> analysis using adenoviruses confirmed that HAUSP, but not the HAUSP C223S mutant, decreased blood glucose and triglyceride levels, which are associated with the increased expression of endogenous PPARγ and lipid accumulation in the liver. Our results demonstrate that the stability and activity of PPARγ are modulated by the deubiquitinating activity of HAUSP, which may be a target for the development of anti-diabetic drugs.</P>

Clinical outcomes of patients with hepatorenal syndrome after living donor liver transplantation

Lee, Jung Pyo,Kwon, Hyuk Yong,Park, Ji In,Yi, Nam‐,Joon,Suh, Kyung‐,Suk,Lee, Hae Won,Kim, Myounghee,Oh, Yun Kyu,Lim, Chun Soo,Kim, Yon Su Wiley Subscription Services, Inc., A Wiley Company 2012 Liver transplantation Vol.18 No.10

<P><B>Abstract</B></P><P>Liver transplantation (LT) is the treatment of choice for hepatorenal syndrome (HRS). However, the clinical benefits of living donor liver transplantation (LDLT) are not yet well established. We, therefore, investigated the outcomes of patients with HRS who underwent LDLT and patients with HRS who received transplants from deceased donors. This study focused on 71 patients with HRS out of a total of 726 consecutive adult Korean patients who underwent LT at a single Asian center. We compared 48 patients who underwent LDLT with 23 patients who underwent deceased donor liver transplantation (DDLT). Patients with HRS showed poorer survival than patients without HRS (<I>P</I> = 0.01). Poorer survival was associated with higher in‐hospital mortality for patients with HRS (18.3% versus 5.2%, <I>P</I> < 0.001). In comparison with DDLT, LDLT was associated with younger donors and shorter ischemic times. The survival rate with LDLT was significantly higher than the survival rate with DDLT (<I>P</I> = 0.02). Among patients with high Model for End‐Stage Liver Disease scores (≥30) or type 1 HRS, the survival rates for the LDLT group were not inferior to those for the DDLT group. LDLT significantly improved recipient survival after adjustments for several risk factors (hazard ratio = 0.20, 95% confidence interval = 0.05‐0.85, <I>P</I> = 0.03). Kidney function was significantly improved after LT, and there was no difference between LDLT and DDLT. No patients in the HRS cohort required maintenance renal replacement therapy. In conclusion, LDLT may be a beneficial option for patients with HRS. Liver Transpl 18:1237–1244, 2012. © 2012 AASLD.</P>

Twinning and slip behaviors and microstructural evolutions of extruded Mg-1Gd alloy with rare-earth texture during tensile deformation

Lee, Sang Won,Kim, Sang-Hoon,Jo, Wan-Kuen,Hong, Won-Hwa,Kim, Woong,Moon, Byoung Gi,Park, Sung Hyuk Elsevier 2019 JOURNAL OF ALLOYS AND COMPOUNDS Vol.791 No.-

<P><B>Abstract</B></P> <P>An extruded Mg-1Gd alloy with a non-basal texture, whose basal poles are tilted 60.9° from the extrusion direction (ED), exhibits a high room-temperature tensile elongation of 37.2%. This study investigates the active deformation mechanisms and microstructural evolutions of this highly ductile extruded alloy during tensile deformation through <I>in situ</I> electron backscatter diffraction analysis. When tensile strain is applied along the ED, a small amount of {10-12} twins is formed at the early stage of deformation, and the twins gradually grow with increasing applied strain. However, {10-11} twins and {10-11}-{10-12} twins, which are generally observed in extruded Mg alloys with a typical basal fiber texture, are not formed during deformation. The tilted initial texture is favorable for basal slip, and therefore, basal slip is vigorously activated during tension. As a consequence, the average angle between the <I>c</I>-axis of the grains and the ED increases from 60.9° to 66.3° as the applied tensile strain increases from 0% to 30%. Prismatic slip is also activated during tension, which is confirmed by the gradual increase in the rotation angle of the prismatic poles around the <0001> axis during deformation. The activation of prismatic slip causes a significant reduction in the texture intensity of the alloy during deformation. The high ductility of the Mg-1Gd alloy is attributed mainly to the activation of {10-12} twinning, which is beneficial to elongation, instead of the activation of {10-11} twinning, which is detrimental to elongation, and the promoted activation of basal and non-basal slips. Furthermore, microstructural characteristics such as the fully recrystallized structure, large average grain size, and absence of second-phase particles also contribute to the high ductility of the alloy.</P> <P><B>Highlights</B></P> <P> <UL> <LI> Tensile deformation behaviors of Mg-1Gd alloy with an RE texture are investigated. </LI> <LI> {10-12} Twins—not {10-11} twins detrimental to elongation—are formed under tension. </LI> <LI> Basal poles move away from the ED with deformation by the activation of basal slip. </LI> <LI> Lattice rotation by activation of prismatic slip causes gradual texture weakening. </LI> <LI> The alloy's high ductility is due mainly to the activation of twinning and slips. </LI> </UL> </P>

Effects of acute caffeine ingestion on aerobic/anaerobic capacity and isokinetic muscular function in collegiate soccer players

( Won Hyuk Choi ),( Hyun Seok Cho ),( Man Gyoon Lee ) 한국체육학회 2016 국제스포츠과학 학술대회 Vol.2016 No.1

Purpose: Caffeine has been well known as an ergogenic aid. However, the effects of acute caffeine ingestion in soccer players who require high level of aerobic and anaerobic capacity need to be elucidate. The purpose of the study was to examine the effects of acute ingestion of caffeine on aerobic/anaerobic capacity and isokinetic muscular function in soccer players. Method: Eighteen collegiate soccer players were randomly assigned into caffeine group (n=9) or placebo group (n=9). All subjects in both group participated in pre-test without caffeine ingestion for four days, followed by post-test without caffeine ingestion for another four days. Subjects in caffeine group ingested caffeine capsule one hour before post-test, whereas subjects in placebo group ingested cellulose capsule at the same time point. Caffeine or placebo was ingested by double blind method, and the amount of caffeine ingestion was 6 mg per 1 kg of body weight. Main dependant variables were anaerobic capacity, aerobic capacity, and isokinetic muscular function. Anaerobic capacity included counter movement jump as well as peak power, average power, and lowest power obtained from the Wingate test. Aerobic capacity included maximal oxygen uptake (VO2max), time to exhaustion, and anaerobic threshold obtained from maximal graded exercise test. Isokinetic muscular function included peak torque, peak torque per body weight, total work, and total work per body weight of dominant and non-dominant knee measured at 60°·sec-1 using Cybex 770. All date were compared between two groups (caffeine group and placebo group) and between two test (pre-test and post-test) using a two-way ANOVA with repeated measures Result: 1) Counter movement jump was significantly improved in caffeine group(P<.05). 2) Peak power, average power, and lowest power(P<.01) obtained from the Wingate test were significantly improved in caffeine group. 3) Time to exhaustion measured during the maximal graded exercise test was significantly increased in caffeine group(P<.01). 4) Peak torque(P<.05), peak torque per body weight(P<.05), total work(P<.05), and total work per body weight(P<.05) of non-dominant knee measured at 60°·sec-1 were significantly improved in caffeine group. Conclusion: Acute caffeine ingestion would contribute for improving aerobic and anaerobic ca-pacity in male soccer players.