• Journal of Mechanical Science and Technology
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• v.17 no.10
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• pp.1563-1571
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• 2003

A fast response NO analyzer was applied to investigate the relation between cycle-by-cycle NO emissions and combustion chamber pressure. NO emissions were sampled at an isolated exhaust manifold of 4-stroke spark ignition engine to avoid the interference of exhaust gas from other cylinders. The linear correlation analysis was performed with collected data of NO emissions and combustion chamber pressure with respect to the various air-fuel mixture ratios and engine loads. The sampled data sets were obtained during 200 cycles at each operating condition. The results showed that there was a typical pattern in NO emissions from an exhaust port through a cycle. It was possible to set a block of crank angle in which the linear correlation coefficient between NO emissions and combustion chamber pressure was high. As the engine load increased, NO emissions were more dependent on combustion chamber pressure after TDC. It was also analyzed that the correlation between two parameters with respect to air-fuel mixture ratio tended to increase as mixture went leaner. Furthermore, this correlation coefficient for the mixture near the lean limit seemed to be kept high even though combustion was unstable.

• BMB Reports
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• v.41 no.3
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• pp.223-229
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• 2008

Reactive oxygen species (ROS) are implicated in vascular homeostasis. This study investigated whether ${O_2}^{\cdot^-}$, the foundation molecule of all ROS, regulates vasomotor function. Hence, vascular reactivity was measured using rat thoracic aortas exposed to an ${O_2}^{\cdot^-}$ generator (pyrogallol) which dose-dependently regulated both $\alpha$-adrenergic agonist-mediated contractility to phenylephrine and endothelium-dependent relaxations to acetylcholine. Pyrogallol improved and attenuated responses to acetylcholine at its lower (10 nM - 1 ${\mu}M$) and higher (10 - 100 ${\mu}M$) concentrations, respectively while producing the inverse effects with phenylephrine. The endothelial inactivation by L-NAME abolished acetylcholine-induced vasodilatations but increased phenylephrine and KCl-induced vasoconstrictions regardless of the pyrogallol dose used. Relaxant responses to sodium nitroprusside, a nitric oxide donor, were not affected by pyrogallol. Other ROS i.e. peroxynitrite and $H_2O_2$ that may be produced during experiments did not alter vascular functions. These findings suggest that the nature of ${O_2}^{\cdot^-}$-evoked vascular function is determined by its local concentration and the presence of a functional endothelium.

• International Journal of Contents
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• v.13 no.3
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• pp.65-74
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• 2017

Women's menopause is a natural process that every woman must eventually experience, but changes in hormones before and after menopause can serve to produce life-threatening crises in some situations, with individual differences. Data for the study was elicited from 22,610 Korean women ranging in age from 45 to 55 years in the 2013 Korean Community Health Survey. Statistical analyses was performed using descriptive, t-test, ANOVA, and hierarchical regression analysis using SPSS IBM 20.0 version. Individual characteristics, lifestyle, history of chronic disease(s), psychological and environmental factors were included as independent and EQ5D weights of Koreans were used as dependent variables. The survey subjects consisted of a total 15,505(58.3%) in their 50s, 1,765 (66.5%) in middle and high school dropouts or graduates, 22,174 (83.3%) living in spouses and 10,534(39.6%) in wages. There was a significant difference in HRQOL among all independent variables except drinking and residential areas. Hierarchical regression analysis showed that age, smoking, obesity and other incidental disease factors (fall, angina, asthma, arthritis, osteoporosis, stroke) had a negative effect on HRQOL. The selected independent variables accounted for 22.7% of HRQOL. It is necessary to find a way to improve HRQOL of Korean perimenopausal women, focusing on the significant variables revealed by the study results.

• Journal of ILASS-Korea
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• v.6 no.1
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• pp.25-34
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• 2001

Several efforts to meet the exhaust gas regulation have been undertaken by many researchers in recent years. Main researches are on development of design techniques of intake port and combustion chamber, atomisation of fuel and precise control of air-fuel ratio, post-treatment of exhaust gas and so on. Engine technology is changed from PFI to GDI to correspond with exhaust gas regulation. GDI technique makes it possible to preserve lean air-fuel ratio and control accurate air-fuel ratio. Nevertheless, It is not cleared that information of spray characteristics and atomization process are very dependent on fluctuation of pressure and change of temperature in intake stroke. In this study, a constant volume combustion chamber is manufactured to investigate various fluctuations of in-cylinder pressure for injection duration. It is taken photographs of injection process of conventional GDI injector using PMAS. Then, it was verified experimently that ambient conditions as temperature and pressure of combustion chamber have effects on process of spray growth and atomization of fuel.

• Korean Journal of Health Education and Promotion
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• v.13 no.2
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• pp.97-114
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• 1996

Recently, attention for health promotion is rising. Alcohol is widely consumed among adults. About 1/3 of people 15 years of older enjoy drinking alcohol. Some 80% of them drink a half or more bottle of soju each time. Regular excessive drinking of alcohol may cause various problems. WHO(1990) reported that social problems such as divorce, unemployment, and financial difficulties ; psychological problems such as melancholy, suicide, and drug abuse ; physical problems such as cirrhosis, lung cancer, high blood pressure, stroke, and sterilization. The patients with liver disease are estimated to be 628,000. Approximately, 12,000 persons are dying by chronic liver disease and cirrhosis each year. Among the people of 15 years or older, persons dependent on alcohol are estimated to be 1,480,000. This study suggests policies to reduce the consumption of alcohol for planning for health promotion. Limitations of sites and times of sales and designation of sellers, designation of sites prohibiting drinking, limitation of alcohol sales promotion, and restrictions on advertisement can be inaugurated. Increase of price through the raise of tax and taxation of promotion cost. Education of high risk groups such as soldiers, pregnant women, and the youth can be introduced. Provision of alternative socialization programs instead of drinking. Some approaches on target groups were suggested.

• Biomedical Science Letters
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• v.26 no.3
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• pp.164-169
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• 2020

Atherosclerosis is a cardiovascular disease in which plaque builds up inside of an artery and can lead to various complications such as myocardial infarction, stroke, and thrombosis. Recently, hypertriglyceridemia has attracted significant attention as contributors to development of atherosclerosis. However, molecular mechanism of its contribution to atherosclerosis is poorly understood. Here we proposed a potential link between triglyceride (TG) and atherosclerosis. TG treatment promoted downregulation of certain scavenger receptor, macrophage scavenger receptor-1 (MSR-1) in phorbol myristate acetate (PMA)-derived human macrophages. TG treatment caused reduction of MSR-1 mRNA expression in a time- and dose-dependent manner. Using chemical inhibitors, we found that inhibition of signaling pathways associated with PI3K and PLC enhances TG-induced reduction of MSR-1 expression in THP-1 macrophages implying that PI3K and PLC is implicated in the expression of MSR-1 in macrophages. Since MSR-1 is associated with uptake and clearance of atherogenic lipoprotein, oxidized low density lipoprotein (oxi-LDL), our data suggest that increase of oxi-LDL due to TG-mediated reduction of its receptor MSR-1 can promote atherosclerosis.

• Proceedings of the Korean Society of Applied Pharmacology
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• 2003.11a
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• pp.67-67
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• 2003

Minocycline is known to protect neurons from microglia-mediated cell death in many experimental models of brain diseases including ischemic stroke, Huntingtons disease (HD), amyotrophic lateral sclerosis (ALS), traumatic brain injury, multiple sclerosis, and Parkinsons disease. When the activity of caspases was assessed using their fluorescent peptide substrates, activation of caspase-2, 3, 8, and 9 was evident within 2 8 hr following oxidative insult with 0.5 mM hydrogen peroxide in PC12 cells. Minocycline significantly attenuated activation of these caspases up to 18 hr, resulting a significant increase in the cell viability as assessed by MTT assay as well as trypan blue staining. However, cleavage of alpha-spectrin and a cdk5 activator p35, which are known to be substrates for calpain, remained unchanged in the presence of minocycline, suggesting that minocycline did not block caspase-3-independent cell death or necrosis. Moreover, co-treatment with minocycline and a calpain inhibitor calpeptin synergistically inhibited hydrogen peroxide-induced cell death. These data suggest that minocycline directly inhibited apoptosis, but not necrosis, after oxidative insult in PC12 cells.

• Environmental Analysis Health and Toxicology
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• v.19 no.3
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• pp.287-294
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• 2004

Diabetic complication is one of major risk factors leading to vascular disease such as atherosclerosis, stroke, coronary heart disease and etc. Several factors affecting the acceleration of diabetic vascular complication have been known such as hypertension, hyperlipidemia, immune complex and genetic factors. To screen and develop new therapeutics agents for diabetic vascular complication, it is strongly needed to develop animal models for diabetic complications. However in rodents models, diabetic complications is not well developed. Furthermore to assess the possibility of new therapeutics for diabetic vascular complications, diabetic animal models which have the risk factors of diabetic complications is needed. We aim to develop and establish an diabetic animal model which have diabetic complications with hyperlipidemia which is one of risk factors for diabetic complications. We induced insulin -dependent diabetes by intra. venous injection of streptozotocin (35 mg/kg/day) in RICO rats which is a spontaneous animal model for hyperlipidemia. Our models (STZ RICO) showed hyperglycemia, persistent high level of plasma cholesterol and triglyceridemia with severe diabetic renal changes until 28 weeks after induction of diabetes. STZ-RICO rats could be used for the evaluations of newly developed diabetic drugs.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.12 no.5
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• pp.389-396
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• 2002

In this study, the dynamic absorbing system for gas operated gun has been investigated. For this purpose, firstly. mathematical model of gas-operated shoulder-fired gun has been constructed. Through a series of experimental works using the devised test setup, the characteristic behavior of mathematical model was compared to the test results. In order to design the dynamic absorbing system, parameter optimization process has been performed based on the simplified isolation system under constraints of moving displacement and transmitted force. In order to implement the more efficient dynamic absorbing system, the characteristic performance of stroke-dependent variable damping system has been analyzed with some opening area curves. Finally, the performance of the designed dynamic absorbing system has been evaluated by simulation and experiment using the previous test apparatus.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 2008.10a
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• pp.147-150
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• 2008

Vitamin C ascorbic acid (AA) and dehydroascorbic acid (DHA) as an antioxidant have been shown to have protective effects in experimental neurological disorder models such as stroke, ischemia, and epileptic seizures. The present study was conducted to examine the protective effect of AA and DHA on Kainic acid (KA) neurotoxicity using organotypic hippocampal slice cultures (OHSC). After 12h KA treatment, significant delayed neuronal death was detected in CA3 region, but not in CA1. Intermediate dose of AA and DHA pretreatment significantly prevented cell death and inhibit ROS level, mitochondrial dysfunction and capase-3 activation in CA3 region. In the case of low or high dose, however, AA or DHA pretreatment were not effective. These data suggest that both AA and DHA pretreatment have neuroprotective effects on KA-induced neuronal injury depending on the concentration, by means of inhibition of ROS generation, mitochondrial dysfunction, and caspase-dependent apoptotic pathway.