• The Journal of Korean Medicine
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• v.26 no.3 s.63
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• pp.188-203
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• 2005

Objectives : This study was designed to investigate the effects of Jayun-tang extract (JYT) on the change of cerebral hemodynamics [regional cerebral blood flow (rCBF), pial arterial diameter (PAD) and mean arterial blood pressure (MABP)] in normal and cerebral ischemic rats, na to determine the mechanisms of action of JYT. Methods : We investigated whether JYT inhibits lactate dehydrogenase activity in neuronal cells and cytokines production in serum of cerebral ischemic rats. Results : 1. JYT significantly increased rCBF and PAD in a dose-dependent manner, but MABP was not changed by injecting JYT. These results suggested JYT significantly increased rCBF by dilating PAD. 2. The JYT-induced increase in rCBF was significantly inhibited from pretreatment with indomethacin (1mg/kg, i.p.), an inhibitor of cyclooxygenase and methylene blue $(10{\mu}g/kg, i.p.)$, an inhibitor of guanylate cyclase. 3. The JYT-induced dilation in PAD was significantly inhibited from pretreatment with indomethacin, but was increased by pretreatment with methylene blue. 4 The JYT-induced increase in MABP was reduced by pretreatment with indomethacin and methylene blue. 5. JYT significantly inhibited lactate dehydrogenase activity in neuronal cells. These results suggest that JYT prevented the neuronal death. 6. Both rCBF and PAD were significantly and stably increased by JYT $(10{\mu}g/kg,\;i.p.)$ during the Period or cerebral reperfusion, which contrasted with the findings of rapid and marked increase in the control group. 7. In cytokine production in the serum drawn from femoral artery 1hr after middle cerebral artery occlusion, the sample group showed significantly decreased production of $IL-1\beta$ and $TNF-\alpha$ as well as increased production of IL-10 and $TGF-\beta$ compared with rho control group. 8. In cytokine production in the serum drawn from femoral artery 1hr after reperfusion, the sample group showed significantly decreased production of $IL-1\beta$ and $TNF-\alpha$ as well as significantly increased production of IL-10 and $TGF-\beta$ compared with the control group. Conclusions : JYT mediated by cyclooxygenase had an inhibitive effect on brain damage by inhibiting lactate dehydrogenase activity, $IL-1\beta$ and $TNF-\alpha$ production, and by accelerating IL-10 and $TGF-\beta$ production. The author feels that JYT had anti-ischemic effects through the improvement of cerebral hemodynamics and inhibitive effects on brain damage.

• Journal of Drive and Control
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• v.11 no.4
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• pp.53-60
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• 2014

This paper proposes a control scheme to reduce the power consumption of a variable displacement swash-plate type piston pump supplying oil to a valve-controlled hydraulic cylinder at constant pressure. Whenever flow rate demand was absent, the swash plate angle and the pump speed were changed to the minimum values required to compensate for the internal leakage flow. In response to command signals, the pump speed was changed in proportion to the absolute mean value of the speed component for position commands. At the same time, a pressure regulator was activated to maintain constant system pressure by precisely adjusting the pump speed with the swash plate angle fixed at the maximum. The conventional system consisting of a pressure-compensated variable displacement type pump is driven at a constant speed of 1,800rpm. By comparison, computer simulation and experimental results showed that idling power at stand-by status could be reduced by up to 70% by reducing the pump speed from 1,800rpm to 300rpm and the swash plate angle to the minimum.

• Journal of Drive and Control
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• v.15 no.2
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• pp.32-37
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• 2018

The power plants use turbine output control devices to supply or shut off steam to high pressure and low-pressure steam turbines connected to generators. This turbine output control device is driven by a hydraulic servo actuator. The gas flows into the hydraulic servo actuator during periodic inspection or normal operation, and the resulting adiabatic compression of the gas raises the internal temperature of the actuator to $500^{\circ}C$. This temperature increase causes the seals to burn and show wear and tear, resulting in failure. In this study, an air vent valve was installed to allow gas inside the hydraulic servo actuator to flow large quantities of air at the beginning of the operation and after the periodic inspection. Gas was passed through for only minute flow during normal operation of the power plant. By applying the air vent valve, it improves the reliability of the hydraulic servo actuator by discharge the gas appropriately to improve the life of the seal.

• 제어로봇시스템학회:학술대회논문집
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• 2005.06a
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• pp.275-280
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• 2005

The principal context of this research is the approach to an artificial neural network algorithm which solves multivariable nonlinear equation systems by estimating the state of line power flow. First a dynamical neural network with feedback is used to find the minimum value of the objective function at each iteration of the state estimator algorithm. In second step a two-layer neural network structures is derived to implement all of the different matrix-vector products that arise in neural network state estimator analysis. For hardware requirements, as they relate to the total number of internal connections, the architecture developed here preserves in its structure the pronounced sparsity of power networks for which state the estimator analysis is to be carried out. A principal feature of the architecture is that the computing time overheads in solution are independent of the dimensions or structure of the equation system. It is here where the ultrahigh-speed of massively parallel computing in neural networks can offer major practical benefit.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2004.03a
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• pp.550-559
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• 2004

Theoretical studies have been carried out to examine the influence of the grain geometry-dependent driving forces, which control the internal flow pattern of solid rockets. Numerical studies have been executed with the help of a two-dimensional code. This code solves standard k-omega turbulence equations using the coupled second order implicit unsteady formulation. It has been concluded that the grain port divergence angles have significant leverage on the formation of recirculation bubbles leading for pressure oscillations, flow separation and reattachment. In solid rockets flow reattachment will favour secondary ignition and that will add to the complexity of the starting transient prediction.

• Proceedings of the KIEE Conference
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• 2002.07c
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• pp.1536-1538
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• 2002

Effects at thermal treatment on the structural and electrical properties at DLC films have been studied. The DLC films were deposited by using a modified FCVA system as a function at negative substrate bias voltage, deposition time, and nitrogen flow rate. The thermal treatment on DLC films could be achieved by performing the RTA process at $600^{\circ}C$, 2min. Structural investigation on the thermal treatment effect was evaluated by inspecting the Raman spectroscopy, XPS, AFM, and internal compressive stress. In addition, the electrical properties of DLC films were evaluated by using the high current source and Lab-View data acquisition system. As the result at RTA treatment, $sp^3/sp^2$ ratio and internal compressive stress of the DLC films were decreased tram 5% to 22% and from 1GPa to 3GPa, and the $I_D/I_G$ intensity ratios was increased from 0.19 to 0.35. It was also found that the variation of internal stress of DLC films strongly agree with the variation of $sp^3/sp^2$ fraction and $I_D/I_G$ intensity ratio.

• Transactions of the Korean Society of Mechanical Engineers
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• v.15 no.6
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• pp.1861-1871
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• 1991

In this study, the piping system conveying unsteady flow is considered. The effects of coupling between the pipe motion and the velocity and pressure of fluid are included for the dynamic stability and response analysis of the piping system. The dynamic equations for a piping system are derived by Newtonian dynamics. For the momentum and continuity equations, the concept of moving control volume is applied. Thus, the governing equations derived herein are valid for the applications to the vibration problems occurred when a piping system starts up or shuts down and also when the valves and pumps operate. For a simply supported straight pipe, the stability analysis is conducted for various nondimensional parameters. The dynamic responses, in both stable and unstable region of stability chart, are numerically tested by the use of central difference method.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.39 no.6
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• pp.559-566
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• 2011

This paper presents the flow passage design for a window cooling device, which have a conical poppet valve and an emissive orifice. Computational flow analysis and experiment are conducted according to the poppet strokes. The results show satisfactory flow characteristics that pressure is reduced enough to endure material strength and the flow does not choked inside window. The correction factor of discharge coefficients is found between 2-dimensional analysis and experiments, which is applied to control coolant flow rates of the window cooling device.

• The Journal of Internal Korean Medicine
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• v.29 no.3
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• pp.742-751
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• 2008

Objective: The purpose of this study was to evaluate the effect of Samjawhadam-jeon (SJHDJ; 三子化痰煎) on immune cells in OVA-induced asthmatic mice. Material and Methods : C57BL/6 mice were injected, inhaled and sprayed with OVA for 12 weeks (four times a week) for asthma induction. Two experimental groups were treated with different concentrations of SJHDJ group (400 mg/kg) extracts and cyclosporin A (10 mg/kg) for the latter 8 weeks. At the end of the experiment, the mouse lung. peripheral lymph node (PLN) and spleen were removed and immune cells were analyzed by flow cytometer. Results : Lung weight, total cells in lung, PLN, and spleen of the SJHDJ group decreased significantly compared with that of the control group. Number of $CD3e^+/CD69^+$, $CD3e^+/DX5^+$ cells in lung, PLN and spleen, number of $CD3^+$ cells in PLN and spleen, number of $CD3e^-/CCR3^+$ cells in lung and PLN, and number of $B220^+/IgE^+$ cells in PLN of the SJHDJ group decreased compared with that of the control group. Number of $CD4^+/CD25^+$ cells in PLN and spleen of the SJHDJ group increased compared with that of the control group. Conclusion : These results demonstrate that SJHDJ will be a desirable alternative therapy for allergic asthma by inhibiting the expression of immune cells.

• Journal of Haehwa Medicine
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• v.17 no.1
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• pp.67-74
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• 2008

Objective: The purpose of this research is to examine the effects of Mahaenggamseok-tang-gagambang (MGTG) on CD3+ T cells, CD4+ T cells and CD8+ T cells in ovalbumin (OVA)-induced asthmatic mice. Methods: C57BL/6 mice were injected, inhaled and sprayed with OVA for 12 weeks (four a week) for asthma induction. Two experimental groups were treated with different concentrations of MGTG (400 mg/kg and 200 mg/kg) extract and cyclosporin A (10 mg/kg) for the later 8 weeks. At the end of the experiment, the mice lung was removed and analyzed CD3+ T cells, CD4+ T cells and CD8+ T cells by flow cytometer. Results: Numbers of CD3+ T cells in lung of the MGTG groups (200, 400 mg/kg) were significantly decreased compared with that of control group. Numbers of CD4+ T cells in lung of the MGTG groups (200, 400 mg/kg) were significantly decreased compared with that of control group. Numbers of CD8+ T cells in lung of the MGTG groups (200, 400 mg/kg) were significantly decreased compared with that of control group. Conclusion: The results of this study suggest that MGTG alleviated asthmatic hyperreactiviry through CD4+ and CD8+ T cells. Further study of relative cytokines is expected.