• Proceedings of the SAREK Conference
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• 2007.11a
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• pp.270-275
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• 2007

Pollutants emitted by Diesel trains seriously affected on the ventilation characteristics in the subway or railway tunnel network systems. Thus, numerical prediction results and analyses are required to engineers who should design ventilation facilities. So here, this paper presents some numerical results about the ventilation characteristics, such as pollutants distributions and a suitability of the ventilation facilities pre-designed in case that diesel trains use the same railway track with normal passenger trains

• Journal of Institute of Control, Robotics and Systems
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• v.13 no.6
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• pp.560-567
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• 2007

The objective of this research is to optimize the designing parameters of the parallel manipulator with large orientation workspace at the boundary position of the constant orientation workspace (COW). The method uses a simple genetic algorithm(SGA) while considering three different kinematic performance indices: COW and the global conditioning index(GCI) to evaluate the mechanism's dexterity for translational motion of an end-effector, and orientation workspace of two angle of Euler angles to obtain the large rotation angle of an end-effector at the boundary position of COW. Total fifteen cases divided according to the combination of the sphere radius of COW and rotation angle of orientation workspace are studied, and to decide the best model in the total optimized cases, the fuzzy inference system is used for each case's results. An optimized model is selected as a best model, which shows better kinematic performances compared to the basis of the pre-existing model.

• Corrosion Science and Technology
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• v.6 no.5
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• pp.245-250
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• 2007

Recently, to avoid global warming, reduction of $CO_2$ generation has been demanded. Each car manufacture takes positive actions for improvement in fuel consumption by various kinds of countermeasures, e.g. improving engine efficiency, using alternative fuels, lightening the car body. Regarding lightening of the car body, aluminum alloys and high tensile strength steels has been gradually adopted as lightweight materials. However, such materials are normally not easy to be treated with zinc phosphate system. Focusing the pre-treatment processes, low temperature phosphate system could be demanded for energy saving. This time, new surface conditioning process for lightweight materials and low temperature phosphate system shall be discussed.

• Research in Community and Public Health Nursing
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• v.23 no.3
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• pp.316-326
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• 2012

Purpose: This study was to identify the factors associated with stages of exercise behavior change of residents in a community on the basis of the Transtheoretical Model. Methods: Data were collected from 520 residents of a community using a self-report questionnaire. The survey variables comprised the stages of exercise behavior change, the process of change, decisional balance and self efficacy. Results: There were significant differences in the process of change, decisional balance and self efficacy by the stages of exercise behavior change. The factors associated with transition from pre-contemplation to contemplation were consciousness raising and self efficacy; regarding those from contemplation to preparation, cons of the decisional balance and social liberation; regarding those from preparation to action, dramatic relief and counter conditioning; regarding that from action to maintenance, cons of the decisional balance. Conclusion: TTM would be applicable to explain the exercise behavior of some residents in a community, which suggested that the programs for improving exercise behavior of residents in a community need to be developed.

• Analytical Science and Technology
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• v.35 no.5
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• pp.189-196
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• 2022

When cationic basic compounds are chromatographed using hydro-organic mobile phase, the presence of anionic free silanols in the silica-based stationary phases results in broad and asymmetrical peaks. The addition of an ionic reagent to the mobile phase prevents analytes from accessing free silanols, improving peak shape. In this study, the chromatographic behavior of salbutamol sulfate as a basic compound was investigated under various conditions, including the use of different columns, mobile phases, and ion-pair reagents such as triethanolamine (TEA) and sodium heptane sulfonate (SHS). The retention and peak shape of chromatograms were both evaluated. The results show that pre-conditioning the column with TEA and including it in the mobile phase can prevent cationic analytes from accessing anionic silanols, resulting in improved peak shape. Furthermore, buffering the mobile phase is an important factor in keeping the pH constant throughout the process. The chosen method was validated in part. This study could be helpful for researchers and analyst to solve such problems with cationic basic components.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.29 no.9
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• pp.472-481
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• 2017

Radiant floor heating systems have been used as common heating supply systems in most residential buildings in Korea. Since the system uses a floor as thermal storage, proper control strategy should be adopted to avoid over-or under-heating problems. So far, studies related to control of the floor heating system have been conducted based on computer simulations. The active layer in TRNSYS is known for its usability as a floor heating system model and is integrated with the TRNSYS building model (Type 56). However, floor heating system simulations with the active layer are operated only if pre-defined minimum mass flow rate is ensured. This study proposes a simple RC (Resistance-Capacitance) model for radiant floor heating systems. Model parameters such as Rs and Cs are defined by optimization. The active layer, in this study, is used as the target system to search for optimal values. A TRNOPT optimization tool was used to conduct optimization under given simulation conditions. The RC model with optimal parameters are tested in other mass flow rates that were not used during optimization. Results reveal the RC model describes the active layer with successfully optimized model parameters. The RC model has fewer model limitations, and is expected to be used for various target systems, e.g. experimental data of a real radiant heating system.

• Biomolecules & Therapeutics
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• v.21 no.3
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• pp.196-203
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• 2013

Recent accumulating studies have reported that hypoxic preconditioning during ex vivo expansion enhanced the self-renewal or differentiation of various stem cells and provide an important strategy for the adequate modulation of oxygen in culture conditions, which might increase the functional bioactivity of these cells for cardiac regeneration. In this study, we proposed a novel priming protocol to increase the functional bioactivity of cardiac progenitor cells (CPCs) for the treatment of cardiac regeneration. Firstly, patient-derived c-$kit^+$ CPCs isolated from the atrium of human hearts by enzymatic digestion and secondly, pivotal target molecules identified their differentiation into specific cell lineages. We observed that hCPCs, in response to hypoxia, strongly activated ERK phosphorylation in ex vivo culture conditioning. Interestingly, pre-treatment with an ERK inhibitor, U0126, significantly enhanced cellular proliferation and tubular formation capacities of CPCs. Furthermore, we observed that hCPCs efficiently maintained the expression of the c-kit, a typical stem cell marker of CPCs, under both hypoxic conditioning and ERK inhibition. We also show that hCPCs, after preconditioning of both hypoxic and ERK inhibition, are capable of differentiating into smooth muscle cells (SMCs) and cardiomyocytes (CMs), but not endothelial cells (ECs), as demonstrated by the strong expression of ${\alpha}$-SMA, Nkx2.5, and cTnT, respectively. From our results, we conclude that the functional bioactivity of patient-derived hCPCs and their ability to differentiate into SMCs and CMs can be efficiently increased under specifically defined culture conditions such as short-term hypoxic preconditioning and ERK inhibition.

• International Journal of Air-Conditioning and Refrigeration
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• v.13 no.4
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• pp.167-174
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• 2005

The evaporation heat transfer coefficient of $CO_2$ (R-744) in a horizontal tube was investigated experimentally. The experiments were conducted without oil in a closed refrigerant loop which was driven by a magnetic gear pump. The main components of the refrigerant loop are a receiver, a variable-speed pump, a mass flow meter, a pre-heater and evaporator (test section). The test section consists of a smooth horizontal stainless steel tube of 7.75 mm inner diameter. The experiments were conducted at mass flux of 200 to $500kg/m^2s$, saturation temperature of $-5^{\circ}C\;to\;5^{\circ}C$, and heat flux of 10 to $40kW/m^2$. The test results showed the evaporation heat transfer of $CO_2$ has greater effect on nucleate boiling than convective boiling. The evaporation heat transfer coefficient of $CO_2$ is highly dependent on the vapor quality, heat flux and saturation temperature. The evaporation heat transfer coefficient of $CO_2$ is very larger than that of R-22 and R-134a. In comparison with test results and existing correlations, the best fit of the present experimental data is obtained with the correlation of Jung et al. But the existing correlations failed to predict the evaporation heat transfer coefficient of $CO_2$. Therefore, it is necessary to develop reliable and accurate predictions determining the evaporation heat transfer coefficient of $CO_2$ in a horizontal tube.

• Toxicological Research
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• v.34 no.1
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• pp.65-73
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• 2018

Pretreatment of low-dose lipopolysaccharide (LPS) induces a hyporesponsive state to subsequent secondary challenge with high-dose LPS in innate immune cells, whereas super-low-dose LPS results in augmented expression of pro-inflammatory cytokines. However, little is known about the difference between super-low-dose and low-dose LPS pretreatments on immune cell-mediated inflammatory and hepatic acute-phase responses to secondary LPS. In the present study, RAW 264.7 cells, EL4 cells, and Hepa-1c1c7 cells were pretreated with super-low-dose LPS (SL-LPS: 50 pg/mL) or low-dose LPS (L-LPS: 50 ng/mL) in fresh complete medium once a day for 2~3 days and then cultured in fresh complete medium for 24 hr or 48 hr in the presence or absence of LPS ($1{\sim}10{\mu}g/mL$) or concanavalin A (Con A). SL-LPS pretreatment strongly enhanced the LPS-induced production of tumor necrosis factor (TNF)-${\alpha}$, interleukin (IL)-6, TNF-${\alpha}$/IL-10, prostaglandin E2 ($PGE_2$), and nitric oxide (NO) by RAW 264.7 cells compared to the control, whereas L-LPS increased IL-6 and NO production only. SL-LPS strongly augmented the Con A-induced ratios of interferon (IFN)-${\gamma}$/IL-10 in EL4 cells but decreased the LPS-induced ratios of IFN-${\gamma}$/IL-10 compared to the control, while L-LPS decreased the Con A- and LPS-induced ratios of IFN-${\gamma}$/IL-10. SL-LPS enhanced the LPS-induced production of IL-6 by Hepa1c1c-7 cells compared to the control, while L-LPS increased IL-6 but decreased IL-$1{\beta}$ and C reactive protein (CRP) levels. SL-LPS pretreatment strongly enhanced the LPS-induced production of TNF-${\alpha}$, IL-6, IL-10, $PGE_2$, and NO in RAW 264.7 cells, and the IL-6, IL-$1{\beta}$, and CRP levels in Hepa1c1c-7 cells, as well as the ratios of IFN-${\gamma}$/IL-10 in LPS- and Con A-stimulated EL4 cells compared to L-LPS. These findings suggest that pre-conditioning of SL-LPS may contribute to the mortality to secondary infection in sepsis rather than pre-conditioning of L-LPS.

• Journal of Korean Academy of Nursing
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• v.41 no.2
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• pp.197-203
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• 2011

Purpose: This study was done to identify whether pre-conditioning exercise has neuroprotective effects against cerebral ischemia, through enhance brain microvascular integrity. Methods: Adult male Sprague-Dawley rats were randomly divided into four groups: 1) Normal (n=10); 2) Exercise (n=10); 3) Middle cerebral artery occlusion (MCAo), n=10); 4) Exercise+MCAo (n= 10). Both exercise groups ran on a treadmill at a speed of 15 m/min, 30 min/day for 4 weeks, then, MCAo was performed for 90 min. Brain infarction was measured by Nissl staining. Examination of the remaining neuronal cell after MCAo, and microvascular protein expression on the motor cortex, showed the expression of Neuronal Nuclei (NeuN), Vascular endothelial growth factor (VEGF) & laminin. Results: After 48 hr of MCAo, the infarct volume was significantly reduced in the Ex+MCAo group ($15.6{\pm}2.7%$) compared to the MCAo group ($44.9{\pm}3.8%$) (p<.05), and many neuronal cells were detected in the Ex+ MCAo group ($70.8{\pm}3.9%$) compared to the MCAo group ($43.4{\pm}5.1%$) (p<.05). The immunoreactivity of laminin, as a marker of microvessels and Vascular endothelial growth factor (VEGF) were intensively increased in the Ex+MCAo group compared to the MCAo group. Conclusion: These findings suggest that the neuroprotective effects of exercise pre-conditioning reduce ischemic brain injury through strengthening the microvascular integrity after cerebral ischemia.