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324 results on '"Hong, Seong Min"'

32. Application of pulse plasma MIG welding process to Al/steel dissimilar joining

Author

Mamat, Sarizam Bin, Tashiro, Shinichi, Masri, Mohamad Najmi, Hong, Seong Min, Bang, Hee-Seon, and Tanaka, Manabu

Abstract

Arc welding of aluminium and steel joins are commonly inundated by the formation of brittle intermetallic compounds (IMC) at the aluminium-steel interface. As the formation of IMC is closely related to the heat input into the base metals, it is hypothesised that the ability to regulate the heat input would enable the control of the thickness of IMC. This paper proposes the use of a pulse plasma MIGW system to regulate the heat input during the welding process. A shadowgraph method was used to compare the weld droplet stability of the pulse plasma MIGW with a pulse MIGW system. It was found that the plasma MIGW generated a regular heat input into the base metal due to the smoothness of the droplet detachment and resulted in the formation of IMC with uniform thickness. Al/steel joining was then conducted using both pulsed plasma MIGW and pulse MIGW systems, and the resulting IMC formations and thicknesses were evaluated. It was found that the formation and thickness of IMC in Al/steel dissimilar welding can be controlled by using pulse plasma MIGW. Its lower droplet temperature and decreased cooling rate during welding would suppress the formation of Fe2Al5and FeAl3, and thus decreasing the overall thickness of IMC at the joining interface.

Published
2024
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33. Stage Optimization of Anti-air Missiles Using Practical Guidance Laws

Author

Hong, Seong-Min, Tahk, Min-Jea, and Lee, Chang-Hun

Abstract

This paper deals with stage optimization of anti-air missiles. Conceptually, stage optimization is a two-loop optimization problem for which the inner loop determines control inputs for the optimal trajectory while the outer loop minimizes the stage weights. In practice, the optimal control inputs are replaced by guidance commands produced by practical guidance laws, resulting in some degradation of the system performance. In this paper, stage optimization considering practical guidance laws for the launch and mid-course guidance phases is proposed to precisely investigate the effect of guidance laws on the stage weights required for the mission. Guidance parameters, virtual target positions, coasting time, and the stage weights are defined as the objective parameters of stage optimization, and the co-evolutionary optimization method is used to find the optimal solution. Applying the proposed method to the stage optimization of a realistic anti-air missile system demonstrates that the missile system needs an extra weight of 4–6 kg compared to the classical two-loop optimization, to meet the same system requirements.

Published
2024
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34. Anti-neuroinflammatory effects of alkaloid-enriched extract from Huperzia serrata on lipopolysaccharide-stimulated BV-2 microglial cells.

Author

Dang, Thu Kim, Hong, Seong-Min, Dao, Vui Thi, Tran, Phuong Thi Thu, Tran, Hiep Tuan, Do, Giang Hoang, Hai, Thanh Nguyen, Nguyet Pham, Hang Thi, and Kim, Sun Yeou

Subjects
*MITOGENS, *MITOGEN-activated protein kinases, *NITRIC-oxide synthases, *TUMOR necrosis factors, *MICROGLIA, *ENZYME-linked immunosorbent assay, *ALKALOIDS
Abstract

Alkaloid-enriched extract of Huperzia serrata (Thunb.) Trevis (Lycopodiaceae) (HsAE) can potentially be used to manage neuronal disorders. This study determines the anti-neuroinflammatory effects of HsAE on lipopolysaccharide (LPS)-stimulated BV-2 microglial cells and the underlying mechanisms. BV-2 cells were pre- or post-treated with different concentrations of HsAE (25-150 µg/mL) for 30 min before or after LPS induction. Cell viability was assessed using a 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide assay and no cytotoxicity was found. Nitric oxide (NO) concentration was determined using Griess reagent. The levels of prostaglandin E2 (PGE2), tumor necrosis factor (TNF)-α, interleukin (IL)-1β, and IL-6 were determined using enzyme-linked immunosorbent assay. The levels of inducible nitric oxide synthase (iNOS) and cyclooxygenase (COX)-2 and the phosphorylation of mitogen-activated protein kinase (MAPK) were analyzed using western blotting. HsAE reduced LPS-induced NO production with half-maximal inhibitory concentration values of 99.79 and 92.40 µg/mL at pre- and post-treatment, respectively. Pre-treatment with HsAE at concentrations of 50, 100, and 150 µg/mL completely inhibited the secretion of PGE2, TNF-α, IL-6, and IL-1β compared to post-treatment with HsAE. This suggests that prophylactic treatment is better than post-inflammation treatment. HsAE decreased the expression levels of iNOS and COX-2 and attenuated the secretion of pro-inflammatory factors by downregulating the phosphorylation of p38 and extracellular signal-regulated protein kinase in the MAPK signaling pathway. HsAE exerts anti-neuroinflammatory effects on LPS-stimulated BV-2 cells, suggesting that it may be a potential candidate for the treatment of neuroinflammation in neurodegenerative diseases. [ABSTRACT FROM AUTHOR]

Published
2023
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36. Hericerin derivatives activates a pan‐neurotrophic pathway in central hippocampal neurons converging to ERK1 /2 signaling enhancing spatial memory

Author

Martínez‐Mármol, Ramón, primary, Chai, YeJin, additional, Conroy, Jacinta N., additional, Khan, Zahra, additional, Hong, Seong‐Min, additional, Kim, Seon Beom, additional, Gormal, Rachel S., additional, Lee, Dae Hee, additional, Lee, Jae Kang, additional, Coulson, Elizabeth J., additional, Lee, Mi Kyeong, additional, Kim, Sun Yeou, additional, and Meunier, Frédéric A., additional

Published
2023
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44. Trust Management for Resilient Wireless Sensor Networks

Author

Hur, Junbeom, Lee, Younho, Hong, Seong-Min, Yoon, Hyunsoo, Hutchison, David, Series editor, Kanade, Takeo, Series editor, Kittler, Josef, Series editor, Kleinberg, Jon M., Series editor, Mattern, Friedemann, Series editor, Mitchell, John C., Series editor, Naor, Moni, Series editor, Nierstrasz, Oscar, Series editor, Pandu Rangan, C., Series editor, Steffen, Bernhard, Series editor, Sudan, Madhu, Series editor, Terzopoulos, Demetri, Series editor, Tygar, Dough, Series editor, Vardi, Moshe Y., Series editor, Weikum, Gerhard, Series editor, Won, Dong Ho, editor, and Kim, Seungjoo, editor

Published
2006
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47. Total Synthesis of Isohericerinol A and Its Analogues to Access Their Potential Neurotrophic Effects

Author

Vishwanath, Manjunatha, primary, Chaudhary, Chhabi Lal, additional, Park, Yunjeong, additional, Viji, Mayavan, additional, Jung, Chanhyun, additional, Lee, Kwanghee, additional, Sim, Jaeuk, additional, Hong, Seong Min, additional, Yoon, Da Hye, additional, Lee, Dae Hee, additional, Lee, Jae Kang, additional, Lee, Heesoon, additional, Lee, Mi Kyeong, additional, Kim, Sun Yeou, additional, and Jung, Jae-Kyung, additional

Published
2022
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49. Hericerin derivatives activates a pan‐neurotrophic pathway in central hippocampal neurons converging to ERK1/2 signaling enhancing spatial memory.

Author

Martínez‐Mármol, Ramón, Chai, YeJin, Conroy, Jacinta N., Khan, Zahra, Hong, Seong‐Min, Kim, Seon Beom, Gormal, Rachel S., Lee, Dae Hee, Lee, Jae Kang, Coulson, Elizabeth J., Lee, Mi Kyeong, Kim, Sun Yeou, and Meunier, Frédéric A.

Subjects
SPATIAL memory, NEUROTROPHIN receptors, NERVE growth factor, HIPPOCAMPUS (Brain), HERICIUM erinaceus, PERIPHERAL nervous system
Abstract

The traditional medicinal mushroom Hericium erinaceus is known for enhancing peripheral nerve regeneration through targeting nerve growth factor (NGF) neurotrophic activity. Here, we purified and identified biologically new active compounds from H. erinaceus, based on their ability to promote neurite outgrowth in hippocampal neurons. N‐de phenylethyl isohericerin (NDPIH), an isoindoline compound from this mushroom, together with its hydrophobic derivative hericene A, were highly potent in promoting extensive axon outgrowth and neurite branching in cultured hippocampal neurons even in the absence of serum, demonstrating potent neurotrophic activity. Pharmacological inhibition of tropomyosin receptor kinase B (TrkB) by ANA‐12 only partly prevented the NDPIH‐induced neurotrophic activity, suggesting a potential link with BDNF signaling. However, we found that NDPIH activated ERK1/2 signaling in the absence of TrkB in HEK‐293T cells, an effect that was not sensitive to ANA‐12 in the presence of TrkB. Our results demonstrate that NDPIH acts via a complementary neurotrophic pathway independent of TrkB with converging downstream ERK1/2 activation. Mice fed with H. erinaceus crude extract and hericene A also exhibited increased neurotrophin expression and downstream signaling, resulting in significantly enhanced hippocampal memory. Hericene A therefore acts through a novel pan‐neurotrophic signaling pathway, leading to improved cognitive performance. [ABSTRACT FROM AUTHOR]

Published
2023
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