• Transactions of the Korean Society of Mechanical Engineers B
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• 제34권4호
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• pp.365-373
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• 2010

A chemical reactor model (CRM) was developed for a jet stirred reactor (JSR) to predict the emission of exhaust such as NOx. In this study, a two-PSR model was chosen as the chemical reactor model for the JSR. The predictions of NO formation in lean premixed methane-air combustion in the JSR were carried out by using CHEMKIN and GRI 3.0 methane-air combustion mechanism which include the four NO formation mechanisms. The calculated results were compared with Rutar's experimental data for the validation of the model. The effects of important parameters on NO formation and the contributions of the four NO pathways were investigated. In the flame region, the major pathway is the prompt mechanism, and in the post flame region, the major pathway is the Zelodovich mechanism. Under the lean premixed condition, the N2O mechanism is the important pathway in both flame and postflame regions.

• Transactions of the Korean Society of Automotive Engineers
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• 제17권5호
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• pp.46-52
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• 2009

In this study the predictions of NOx in methane-air lean premixed combustion in PSR were carried out with GRI 3.0 methane-air combustion mechanism and Zeldovich, nitrous oxide, prompt, and NNH NO formation mechanism by using CHEMKIN code. The results are compared to the JSR experimental data of Rutar for the validation of the model. This study concerns about the importance of the chemical pathways. The chemical pathway most likely to form the NO in methane-air lean-premixed combustion was investigated. The results obtained with the 4 different NO mechanisms for residence time(0.5-1.6ms) and pressure(3, 4.7, 6.5 atm) are compared and discussed.

• Aerospace Engineering and Technology
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• 제11권2호
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• pp.140-148
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• 2012

For autonomous navigation, map, pose tracking, and finding the shortest path are required. Because there is no GPS signal in indoor environment, the current position should be recognized in the 3D map by using image processing or something. In this paper, we explain 3D map creation technology by using depth camera like Kinect and pose tracking in 3D map by using 2D image taking from camera. In addition, the mechanism of avoiding obstacles is discussed.

• Journal of Applied Biological Chemistry
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• 제63권4호
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• pp.421-428
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• 2020

This study investigated a mixture of Astragalus membranaceus (AM) and Lithospermum erythrorhizon (LE) extracts (ALM16), exerts anti-inflammatory effects in lipopolysaccharide (LPS)-induced RAW264.7 macrophage cells, and its underlying mechanism. ALM16 was prepared by mixing AM and LE extracts in a ratio of 7:3 (w/w). Cytotoxicity of ALM16 in RAW264.7 cells was not shown up to 200 ㎍/mL of ALM16. The results of this study showed that ALM16 does-dependently inhibits the production of nitric oxide, prostaglandin E2 and pro-inflammatory cytokines (interleukin-1β, interleukin-6, and tumor necrosis factor-α) in LPS-induced RAW264.7 cells. ALM16 not only markedly reduced the protein expression levels of inducible nitric oxide synthase and cyclooxygenase-2 (COX-2) in LPS-stimulated RAW264.7 cells, but also inhibited the nuclear translocation and DNA-binding activity of nuclear factor-kappa B (NF-κB). In addition, ALM16 specifically inhibited the phosphorylation of c-Jun N-terminal kinase and extracellular signal-regulated kinases in LPS-stimulated RAW264.7 cells. In conclusion, these results suggest that ALM16 may exert anti-inflammatory effect by modulating mitogen-activated protein kinase and NF-κB signaling pathways.

• Korean Journal of Microbiology
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• 제36권2호
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• pp.91-96
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• 2000

The cultural and physiological conditions for the T-2 toxin [4,15-diacetoxy-8-(3-mety1butyloxy)-12,13- epoxy-trichothec-9-en-3-01, $C_{24}H_{30}O_9$] production by Fusarium spp. were studied. Thin layer chromatography (TLC) assay and the microbiological assay uslng Rhodotomla rubra were used to quantitate tbe T- 2 toxin. Among the four strains of Fusarium spp., F tn'cinctum NRRL 3299 was best for T-2 toxin production. In solid culture, white com grit medium was best for T-2 toxm production. Temperature played a critical role in the production of T-2 toxin. T-2 toxin production was favored by long duration of low-temperature incubation. The growth and toxin production were relatively high on galactose, fructose, glucose, and sucrose media, when each was used as a sole carbon source, and relatively low on sorbitol, glycerol, and lactose media. For nitrogen sources, $NH_4^(+) and NO_3^{-}were used well as a sole nitrogen source, but $NO_2^-$ was not used. Initial pH and speed of shaker also affected the production of T-2 toxin. From temperature shifting experiment, it is clear that T-2 toxin metabolic pathway is regulated by temperature-dependent enzyme depression or enzyme induction system.

• Journal of Preventive Medicine and Public Health
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• 제35권4호
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• pp.269-274
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• 2002

Objectives : To evaluate the elect of glutathione(GSH) on lead induced modulation of nitric oxide(NO) synthesis, and to examine how lead modulates NO production in macrophages. Methods : This study was observed in a culture of RAW 264.7 cells, which originated from a tumor in a Balb/c mouse that was induced by the Abelson murine leukemia virus. The compounds investigated were lead chloride, N-acetyl-cystein(NAC), and Buthionine Sulfoximine( BSO). Results : ATP synthesis in RAW 264.7 cells was unchanged by each lead concentration exposure in a dose dependent manner. The NO synthesis was decreased when exposed to lead($PbCl_2$) concentration $0.5{\mu}M$. The presence of $300{\mu}M$ NAC, used as a pretreatment in the culture medium, caused the recovery of the lead induced decrease in NO synthesis, but in the presence of $300{\mu}M$ BSO as a pretreatment, there was no recoverey. Pretreatment with NAC and BSO had no affect on ATP synthesis at any of the lead concentrations used. Conclusions : These results indicated that GSH has a protective effect toward lead toxicity, and suggested that the inhibition of NO production in macrophage due to lead toxicity may be related to cofactors of iNOS (inducible nitric oxide synthase)

• Journal of KIISE:Software and Applications
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• 제34권4호
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• pp.368-376
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• 2007

How to represent the search space is as important as which search algorithm to use for finding natural-looking paths for moving NPC (non-player character) in computer games. Recently, various state space representation methods which have been developed for computer games are being used while A* algorithm dominates as the preferred search algorithm. These representation methods show some drawbacks such as the size of state space is too large, there is no guarantee for optimality, the path found is not natural-looking, and the generation of nodes and links is not automatic by depending on a level designer. In this paper the requirements for natural-looking paths are introduced and to find paths satisfying these requirements, the use of the generalized visibility graphs which is the extended version of the visibility graph in Robotics is proposed.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제15권6호
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• pp.1251-1255
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• 2011

In this paper, we propose an optimal path search algorithm that contains all nodes using genetic algorithm. An object in this approach is formed as an equation related with the Euclidean distance between an intermediate node and the starting node and between an intermediate node and the goal node. Like other genetic algorithm structures, our algorithm defines a fitness function and selects a crossover spot node and a bitwise crossover point. A new node out of such operation survives only if it satisfies the fitness criteria and that node then becomes the starting node for the next generation. Repetition continues until no changes are made in the population. The efficiency of this proposed approach is verified in the experiment that it is better than two other contestants - sequential approach and the random approach.

• Journal of the Society of Cosmetic Scientists of Korea
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• 제48권3호
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• pp.213-223
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• 2022

In this study, the anti-inflammatory and antioxidant effects of aerial parts of Rumex acetosa L. extract were confirmed to prevent various inflammatory diseases and skin aging caused by excessive oxidative stress. As a result of ABTS assay, it was confirmed that the radical scavenging ability increased in a concentration-dependent manner. ROS inhibitory ability was confirmed through DCF-DA assay, and concentration-dependent inhibition of ROS production was confirmed. The effect of inhibiting cell nuclear damage according to ROS was confirmed through DAPI staining. In addition, it was confirmed that the mRNA expression levels of iNOS and COX-2 were inhibited in a concentration-dependent manner through qPCR. As a result of confirming the protein levels of iNOS and COX-2 by western blotting, iNOS was significantly decreased at all concentrations, and COX-2 was significantly decreased at 800 ㎍/mL. The inhibitory effect on the production of NO generated by iNOS was confirmed by NO assay, and NO was decreased in a concentration-dependent manner. In addition, phosphorylation of ERK and JNK in the MAPKs signaling pathway were inhibited. Therefore, Rumex acetosa L. has the potential to be used as an anti-inflammatory and antioxidant cosmetic raw material by showing anti-inflammatory and antioxidant effects through the MAPKs pathway.

• Journal of the East Asian Society of Dietary Life
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• 제18권2호
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• pp.198-206
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• 2008

갯쑥(Artemisia fukudo Makino, 일명 바다쑥)은 바닷가 염전 주변 습지에서 자라는 염생식물로 어린 갯쑥은 나물로 먹어왔으며, 민간에서 간에 좋다고 알려져 있다. 본 연구에서는 염생식물의 기능 성분을 탐색하는 연구의 일환으로 마우스유래 대식세포주인 RAW264.7세포를 이용하여 갯쑥의 nitric oxide(NO) 생성 억제 작용을 알아보고자 하였다. 갯쑥은 methanol 추출과 열수 추출한 후 농축하여 실험하였고, methanol 추출물은 다시 hexane, chloroform, ethylacetate, butanol, water로 순차 용매 분획하여 농축하여, 각각의 추출물을 RAW 264.7 세포에 농도별 분획별로 처리한 후 LPS와 interferon-${\gamma}$로 자극한 RAW 264.7 세 포주의 NO 생성을 측정하여 NO 생성 저해율을 구하였다. 갯쑥 methanol 추출물의 높은 NO 생성 저해율과 iNOS 활성 저해율을 나타내었으며(IR=90.7%과 IR=81.6%), 각각의 추출물중 분획물이 100${\mu}g/mL$ 농도에서 hexane 분획물이 가장 높은 NO 생성 저해 효과(IR=92.1%)와 iNOS 활성 억제 효과(IR=85.0%)를 나타내었다. 갯쑥의 methanol 추출물, hexane과 chloroform 분획물에서 높은 NO 생성 저해 효과를 나타내어 새로운 암 예방인자 물질로 기대되며, 따라서 본 연구 결과는 암 예방인자 분리를 위한 기초 자료가 될 것이며, 나아가 성분 분리 연구와 동물 실험을 통한 기전 연구가 수행되어야 할 것이다.