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Heerok Hong,김경필,Ho-Yong Lee,김재식,이다솜,김민수,Myung-WonSuh,이정환 대한기계학회 2021 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.35 No.3
During the braking process, frictional heat generated between a disc and a pad can lead to high temperatures. The location of friction blocks on the brake pad can lead directly to differences in friction contact time and friction speed at each point on the brake disc surface, this can lead to non-uniform temperature distribution on the brake disc surface. In this paper, the optimum design for friction blocks on a brake pad is investigated using the design of experiments (DOE) of Taguchi approach and response surface method (RSM) with an aim to minimize the deviation in the rate of friction heating in each area along the radial direction of brake disc. 18 design variables on 2 levels are adjusted. A table of orthogonal arrays, L32 (218), is used. Finite element analysis (FEA) is performed to analyze the mean squared error (MSE) values in the temperature deviations from frictional heat, the disc’s thermo-mechanical characteristics are taken into account. Analysis of variance (ANOVA) is carried out using the data gathered from the DOE stage, we find 7 significant factors among the design variables. A meta-model using RSM is proposed for reduction of temperature deviations over the brake disc. An optimized brake pad is analyzed in terms of the temperature and thermal stress imparted on the brake disc, this optimized pad is then compared with the original pad. The maximum temperatures of the optimized pad and original pad were 399.8 °C and 480.6 °C, respectively. The thermal stress of the optimized pad and original pad were 640.4 MPa and 721.4 MPa, respectively. In the optimized model, the size of the hot band on the disc is larger than that from the original model, so the thermal stress distribution on the disc is smaller. Finally, the optimized pad was found to give significant performance benefits with a 16.8 % decrease in maximum temperature and 11.2 % decrease in thermal stress.
Jung-MeeKim,YounmieJin,Chang-GuHyun,Jong-HeeKim,Hong-SubLee,Dae-KyungKang,Dae-JungKang,Tae-YongKim,Joo-WonSuh,Sang-SoonKang,Soon-KwangHong 한국미생물학회 2002 The journal of microbiology Vol.40 No.3
A 4.8-kb DNA fragment encoding the P-450 type hydroxylase and ferredoxin genes was cloned from Pseudonocardia autotrophica IFO 12743 that can convert vitamin D3 into its hydroxylated active forms. In order to isolate the P-450 gene cluster in this organism, we designed PCR primers on the basis of the regions of an oxygen binding site and a heme ligand pocket that are general characteristics of the P-450 hydroxylase. Sequencing analysis of the BamHI fragment revealed the presence of four complete and one incomplete ORFs, named PauA, PauB, PauC, and PauD, respectively. As a result of computer-based analyses, PauA and PauB have homology with enoyl-CoA hydratase from several organisms and the positive regulators belonging to the tetR family, respectively. PauC and PauD show similarity with SuaB/C proteins and ferredoxins, respectively, which are composed of P-450 monooxygenase systems for metabolizing two sulfonylurea herbicides in Streptomyces griseolus PauC shows the highest similarity with another CytP-450Sca2 protein that is responsible for production of a specific HMG-CoA reductase inhibitor, pravastatin, in S. carbophilus. Cultures of Streptomyces lividans transformant, containing the P-450 gene cluster on the pWHM3 plasmid, was unable to convert vitamin D3 to its hydroxylated forms.
Seong-SooShoi,이진구,Eun-JungHan,Ki-JungHan,Han-KyuLee,JonghoLee,Hong-WonSuh 대한약학회 2003 Archives of Pharmacal Research Vol.26 No.5
Certain polycyclic aromatic hydrocarbons (PAHs) have been reported to induce cytochrome P450 (CYP) 1A1 and 1A2. In the present study, the effects of six well-known PAHs, such as benzo[a]pyrene, benz[a]anthracene, dibenz[a,h]anthracene, chrysene, benzo[k]fluorancene and benzo[b]fluorancene, on the activities of hepatic and pulmonary CYP enzymes were investigated in male ICR mice. When mice were treated intraperitoneally with 3, 10 and 30 mg/ kg of individual PAHs for 3 consecutive days, the activities of ethoxyresorufin- and methoxyresorufin- O-dealkylases were significantly and differentially induced in both liver and lung. Moreover, other CYP isozyme-associated monooxygenase activities were also induced significantly in liver and lung with characteristic induction profiles. Our present results suggest that individual PAHs might have inductive effects on CYP isozymes, and that the characteristic inductive effects of individual PAHs on certain CYP isozymes would be developed as a marker for determining exposure to certain PAHs.
Soo-Hyun Park,Yun Beom Sim,Jin-Koo Lee,Jae-Yong Lee,Hong-WonSuh 대한약학회 2016 Archives of Pharmacal Research Vol.39 No.5
In the present study, we characterized theexpression and role of forkhead box O (FoxO3a) in kainicacid (KA)-induced hippocampal neuronal cell death. FoxO3a and pFoxO3a expression in the CA1, CA2, anddentate gyrus regions in the hippocampus increased 0.5 and1 h after intracerebroventricular administration of KA. Inaddition, both FoxO3a and pFoxO3a expression in thehippocampal CA3 region increased significantly andequally for 1 h but decreased gradually for 24 h after KAadministration. In particular, the KA-induced increases inFoxO3a and pFoxO3a expression in the hippocampal CA3region were inhibited by pretreatment with the N-methyl-Daspartate(NMDA) receptor antagonist (MK-801, dizocilpine,1 lg/5 ll) or a non-NMDA receptor antagonist(CNQX, 6-cyano-7-nitroquinoxaline-2,3-dione, 0.5 lg/5 ll). Furthermore, dizocilpine and CNQX produced aneuroprotective effect against KA-induced neuronal deathin the CA3 region of the hippocampus. Our results suggestthat FoxO3a and pFoxO3 expression is upregulated by KA. Both FoxO3a and pFoxO3a expression appear to beresponsible for KA-induced neuronal death in the CA3region of the hippocampus.