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.

Experiments on the Renal Preservation in Dogs

Lee, Yong Kak,Kim, Chan Hee,Park, Won Hyuk CATHOLIC MEDICAL CENTER 1974 Bulletin of the Clinical Research Institute Vol.2 No.1

The use of cadaver kidneys for transplantation has stimulated considerable interest in the development of methods for short term isolated organ preservation. The techniques used to preserve kidneys and other organs have employed hypothermia, usually in combination with one or more of the following; hyperbaria, metabolic inhibitor and artificial perfusion.

Discrimination of white ginseng origins using multivariate statistical analysis of data sets

Hyuk-Hwan Song,Ji Young Moon,Hyung Won Ryu,노봉수,김정한,Hyeong-Kyu Lee,Sei-Ryang Oh 고려인삼학회 2014 Journal of Ginseng Research Vol.38 No.3

Background: White ginseng (Panax ginseng Meyer) is commonly distributed as a health food in foodmarkets. However, there is no practical method for distinguishing Korean white ginseng (KWG) fromChinese white ginseng (CWG), except for relying on the traceability system in the market. Methods: Ultra-performance liquid chromatography quadrupole time-of-flight mass spectrometrycombined with orthogonal partial least squares discrimination analysis (OPLS-DA) was employed todiscriminate between KWG and CWG. Results: The origins of white ginsengs in two test sets (1.0 mL and 0.2 mL injections) could be successfullydiscriminated by the OPLS-DA analysis. From OPLS-DA S-plots, KWG exhibited tentative markers derivedfrom ginsenoside Rf and notoginsenoside R3 isomer, whereas CWG exhibited tentative markers derivedfrom ginsenoside Ro and chikusetsusaponin Iva. Conclusion: Results suggest that ultra-performance liquid chromatography quadrupole time-of-flightmass spectrometry coupled with OPLS-DA is an efficient tool for identifying the difference between thegeographical origins of white ginsengs.

Stage-specific expression of DDX4 and c-kit at different developmental stages of the porcine testis

Lee, Ran,Lee, Won-Young,Park, Hyun-Jung,Ha, Woo-Tae,Woo, Jae-Seok,Chung, Hak-Jae,Lee, Ji-Heon,Hong, Kwonho,Song, Hyuk Elsevier 2018 Animal reproduction science Vol.190 No.-

<P><B>Abstract</B></P> <P>Spermatogenesis begins with spermatogonial stem cells (SSCs), which are located in the basement membrane of the adult testes. Previous studies have described specific biomarkers for undifferentiated porcine spermatogonia or SSCs; however, these markers are not sufficient to understand spermatogenesis at different developmental stages. The objective of this study was characterize the expression of DEAD-Box polypeptide 4 (DDX4, also known as VASA) and tyrosine-protein kinase kit (c-kit), as potential markers of male germ cells in the porcine testis. In porcine testis tissue at prepubertal stages (5, 30, and 60 days), DDX4 and c-kit protein expression was detected in the most undifferentiated spermatogonia, which also express protein gene product 9.5 (PGP9.5). However, in porcine testis tissues from pubertal and postpubertal stages (90, 120, and 150 days), DDX4 and c-kit were not detected in PGP9.5-positive undifferentiated spermatogonia. The DDX4 expression pattern was similar to that of c-kit in the porcine testis. In adult porcine testes, DDX4-expressing cells were located on the lumenal side, compared to synaptonemal complex protein 3-positive primary spermatocytes, but DDX-4 was not co-expressed with acrosin, a known acrosome marker. In addition, DDX4 was detected in PGP9.5-expressing porcine SSCs in culture. Based on our results, we suggest that DDX4 and c-kit are putative markers of undifferentiated spermatogonia in the prepubertal porcine testis. While in the postpubertal porcine testis, they are markers of differentiated spermatocytes. These findings may facilitate future studies of porcine spermatogenesis.</P> <P><B>Highlights</B></P> <P> <UL> <LI> DDX4 and C-kit were detected in pocine undifferentiated spermatogonia at prepubertal stages. </LI> <LI> DDX4 and C-kit were detected in porcine spermatocyte at postpubertal stages. </LI> <LI> DDX4 expressed spermatocyte was not detected SCP3 and acrosin. </LI> <LI> DDX4 detected in <I>in-vitro</I> cultured porcine undifferentiated spermatogonia. </LI> </UL> </P>

Activated phenoloxidase from Tenebrio molitor larvae enhances the synthesis of melanin by using a vitellogenin-like protein in the presence of dopamine

Lee, Kwang Moon,Lee, Kum Young,Choi, Hye Won,Cho, Mi Young,Kwon, Tae Hyuk,Kawabata, Shun-ichiro,Lee, Bok Luel 부산대학교 유전공학연구소 2000 분자생물학 연구보 Vol.16 No.-

One of the biological functions of activated phenoloxidase in arthropods is the synthesis of melanin around invaded foreign materials. However, little is known about how activated phenoloxidase synthesizes melanin at the molecular level. Even though it has been suggested that the quinone derivatives generated by activated phenoloxdase might use endogenous protein components for melanin synthesis in arthropods, there is no report of protein components engaged in melanin synthesis, we prepared in vitro prophenoloxidase activating solution (designated G-100 solution was incubated with dopamine to induce melanin synthesis in the presence of Ca^2+ and -1,3-glucan, from the hemolymph of larvae of the coleopteran Tenebrio molitor by using a Sephadex G-100 and β-1,3-glucan, four types of protein (160 kDa, prophenoloxidase, phenoloxidase and 45 kDa) disappeared from SDS/PAGE under reducing conditions. Under identical conditions, but including phenylthiourea as a phenoloxidase inhibitor added to the G-100 solution, three of these proteins (160 kDa, phenoloxidase and 45 kDa) did not disappear. To characterize these melanization-engaging proteins, we first purified the 160-kDa melanization-engaging protein to homogeneity and raised a polyclonal antibody against it. Analysis of the cDNA revealed that it consisted of 1439 amino-acid residues and showed partial homology with Caenorhabditis elegans vitellogenin precursor-6 (19.7%). Western blot analysis showed that it disappeared when active phenoloxidase a G-100 solution deficient in it, melanin synthesis was enhanced compared with the same solution without the protein. These data support the conlusion that the 160-kDa vitellogenin-like protein is involved in arthropod melanin synthesis.

Sol-Gel Processed p-Type CuO Phototransistor for a Near-Infrared Sensor

Lee, Sojeong,Lee, Won-Yong,Jang, Bongho,Kim, Taegyun,Bae, Jin-Hyuk,Cho, Kyoungah,Kim, Sangsig,Jang, Jaewon IEEE 2018 IEEE electron device letters Vol.39 No.1

<P>Solution- p-type thin-film transistors, consisting of sol-gel-processed CuO films, were fabricated. The optoelectric properties of sol-gel-processed, CuO-based back gate thin-film transistors were investigated, and a detectivity of <TEX>$1.38\times 10^{ {11}}$</TEX> (cm Hz <TEX>$^{ {1/2}}~\text{W}^{-1})$</TEX> was achieved. This detectivity for sol-gel-processed CuO thin-film transistors is higher than that of the previously reported layered two-dimensional material systems and comparable to that of devices based on a one-dimensional nanowire system. Our results indicate that the sol-gel–processed, CuO-based photodetector system is a promising candidate for applications, such as near-infrared imaging devices, sensors, solar cells, and p-type inks for future printed electronics.</P>

X-ray Crystal Structure and Binding Mode Analysis of Human S-Adenosylhomocysteine Hydrolase Complexed with Novel Mechanism-Based Inhibitors, Haloneplanocin A Analoguest

Lee, Kang Man,Choi, Won Jun,Lee, Yoon Ji,Lee, Hyun Joo,Zhao, Long Xuan,Lee, Hyuk Woo,Park, Jae Gyu,Kim, Hea Ok,Hwang, Kwang Yeon,Heo, Yong Seok,Choi, Sun,Jeong, Lak Shin 梨花女子大學校 藥學硏究所 2011 藥學硏究論文集 Vol.- No.21

The X-ray crystal structure of human S-adenosylhomocysteine (AdoHcy) hydrolase was first determined as a tetrameric form bound with the novel mechanism-based inhibitor fluoroneplanocin A (4b). The crystallized enzyme complex showed the closed conformation and turned out to be the intermediate of mechanism-based inhibition. It confirmed that the cofactor depletion by 3'-oxidation of fluoroneplanocin A contributes to the enzyme inhibition along with the irreversible covalent modification of AdoHcy hydrolase. In addition, a series of haloneplanocin A analogues (4b-e and 5b-e) were designed and synthesized to characterize the binding role and reactivity of the halogen substituents and the 4'-CH(2)OH group. The biological evaluation and molecular modeling studies identified the key pharmacophores and structural requirements for the inhibitor binding of AdoHcy hydrolase. The inhibitory activity was decreased as the size of the halogen atom increased and/or if the 4'-CH(2)OH group was absent. These results could be utilized to design new therapeutic agents operating via AdoHcy hydrolase inhibition.

Bacterial attachment on titanium surface according to topography and chemical changes induced by nonthermal atmospheric pressure

Won-Seok Jeong,Jae-Sung Kwon,Jung-Hwan Lee,Soo-Hyuk Uhm,Eun Ha Choi,Kwang-Mahn Kim 대한치과재료학회 2017 대한치과기재학회 학술대회 Vol.2017 No.4