• Safety and Health at Work
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• v.10 no.1
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• pp.47-53
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• 2019

Background: Despite growing concern over occupational exposure to particulate matter (PM) such as grain dust and diesel exhaust, information about the exposure level and health implications among workers in small-scale milling enterprises in developing countries like Nigeria has not been adequately documented. The purpose of this study was to assess the level of exposure to grain dust and diesel exhaust and effect on lung function among grain millers in food markets in Ibadan metropolis, Nigeria. Methods: The study adopted descriptive cross-sectional design with a comparative approach. Sixteen grain milling shops each were randomly selected from two major food markets in Ibadan metropolis for indoor $PM_{10}$ and $PM_{2.5}$ monitoring. Seventy-two respondents each were proportionately selected from grain millers and shop owners for forced expiratory volume in one second and peak expiratory flow rate tests. Results: The $PM_{2.5}$ concentrations for both market locations ranged between 1,269.3 and $651.7{\mu}g/m^3$, while $PM_{10}$ concentrations were between 1,048.2 and $818.1{\mu}g/m^3$. The recorded concentrations exceeded the World Health Organization guideline limit of $50{\mu}g/m^3$ and $25{\mu}g/m^3$ for $PM_{2.5}$ and $PM_{10}$, respectively. As compared with control group (2.1 L), significantly lower forced expiratory volume in one second value (1.61 L) was observed among the exposed group (p < 0.05). Likewise, significantly lower peak expiratory flow rate value (186.7 L/min) was recorded among the exposed group than the control group (269.51 L/min) (p < 0.05). Conclusion: Exposure to grain dust and diesel exhaust accentuated respiratory disorders with declines in lung functions amongst grain millers. Improved milling practices and engaging cleaner milling facilities should be adopted to minimize exposure and related hazards.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.10 no.1
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• pp.1-17
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• 2016

The separated management and operation of commercial IP/optical multilayer networks makes network operators look for a unified control plane (UCP) to reduce their capital and operational expenditure. Software-defined networking (SDN) provides a central control plane with a programmable mechanism, regarded as a promising UCP for future optical networks. The general control and scheduling mechanism in SDN-based optical burst switching (OBS) networks is insufficient so the controller has to process a large number of messages per second, resulting in low network resource utilization. In view of this, this paper presents the burst-flow scheduling mechanism (BFSM) with a proposed scheduling algorithm considering channel usage. The simulation results show that, compared with the general control and scheduling mechanism, BFSM provides higher resource utilization and controller performance for the SDN-based OBS network in terms of burst loss rate, the number of messages to which the controller responds, and the average latency of the controller to process a message.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2017.05a
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• pp.139-141
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• 2017

By modulating the flow rate of $N_2O$ into a HR motor assembly, a control valve of a hybrid rocket engine plays a role to increase or decrease the thrust. In this study, the control valve has been designed to meet the requirements which are response speed(${\leq}$ about 1 second) and torque(${\geq}$ about $36N{\cdot}m$). Then, when analog signal 0~10V is applied, the situation where the valve is opened and closed has to be realized. To do this, the data values have to be entered into the actuator. Finally, the performance evaluation of the control valve has been performed to validate this product.

• International Journal of Automotive Technology
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• v.7 no.2
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• pp.145-154
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• 2006

In the companion paper, the composition and structure of the MATDYMO (Multi-Agent for Traffic Simulation with Vehicle Dynamic Model) were proposed. MATDYMO consists of the road management system, the vehicle motion control system, the driver management system, and the integration control system. Among these systems, the road management system and the integration control system were discussed In the companion paper. In this paper, the vehicle motion control system and the driver management system are discussed. The driver management system constructs the driver agent capable of having different driving styles ranging from slow and careful driving to fast and aggressive driving through the yielding index and passing index. According to these indices, the agents pass or yield their lane for other vehicles; the driver management system constructs the vehicle agents capable of representing the physical vehicle itself. A vehicle agent shows its behavior according to its dynamic characteristics. The vehicle agent contains the nonlinear subcomponents of engine, torque converter, automatic transmission, and wheels. The simulation is conducted for an interrupted flow model and its results are verified by comparison with the results from a commercial software, TRANSYT-7F. The interrupted flow model simulation is implemented for three cases. The first case analyzes the agents' behaviors in the interrupted flow model and it confirms that the agent's behavior could characterize the diversity of human behavior and vehicle well through every rule and communication frameworks. The second case analyzes the traffic signals changed at different intervals and as the acceleration rate changed. The third case analyzes the effects of the traffic signals and traffic volume. The results of these analyses showed that the change of the traffic state was closely related with the vehicle acceleration rate, traffic volume, and the traffic signal interval between intersections. These simulations confirmed that MATDYMO can represent the real traffic condition of the interrupted flow model. At the current stage of development, MATDYMO shows great promise and has significant implications on future traffic state forecasting research.

• Journal of computational fluids engineering
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• v.6 no.4
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• pp.15-25
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• 2001

Numerical prediction of the diffusion controlled transition in a turbine gas pass is important because it can change the local heat transfer rate over a turbine blade as much as three times. In this study, the gas flow over turbine blade is simplified to the flat plate boundary layer, and an adaptive grid scheme redistributing grid points within the computation domain is proposed with a great emphasis on the construction of the grid control function. The function is sensitized to the second invariant of the mean strain tensor, its spatial gradient, and the interaction of pressure gradient and flow deformation. The transition process is assumed to be described with a κ-ε turbulence model. An elliptic solver is employed to integrate governing equations. Numerical results show that the proposed adaptive grid scheme is very effective in obtaining grid independent numerical solution with a very low grid number. It is expected that present scheme is helpful in predicting actual flow within a turbine to improve computation efficiency.

• Journal of the Korean Society of Safety
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• v.37 no.4
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• pp.20-27
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• 2022

This article aims to develop an algorithm that detects fire pump defects by analyzing the current signals of an induction motor, which are triggered by changes in the flow rate and pressure of multistage volute pumps that are used for fire services. The operational status of the pumps was categorized into three: first, normal operation; second, a defect that is caused by a change in the current value; and third, a defect occasioned by a change in current, pressure, and flow rate. When a fire pump was in normal operation, the motor's operating current was measured between 5.06 A and 6.9 A, the flow rate was estimated at 0-0.27 m³/min, and the pressure ranged from 0 to 0.47 MPa. In the event that a defect was caused by an abnormal current value in the motor, it was attributed to the pump's adherence. Furthermore, if there was no source of water, the defect was considered to have been induced by phase-loss operation, no-load operation, or run-stop operation, with the current value of each scenario being measured at > 52.8 A, < 4.13 A, > 45.15 A, and < 3.8 A, respectively, placing its overall range between 0 and 50 A. The sources of defects were detected based on an analysis of the flow rate, pressure, and current, which represent the following causes: air inflow into the casing, inadequate suction of water, and reverse-phase operation, respectively. Each cause entailed the following values: when air seeped into the casing, the pressure was measured at 0.24 MPa irrespective of changes in the flow rate; when there was inadequate suction of water, the pressure was recorded between 0 and 0.05 MPa despite changes in the flow rate; and when the power line's reverse-phase loss was the cause of the defect, the pressure was measured at 0.33 MPa for a flow rate of 0 L/min, and a higher flow rate decreased the pressure to nearly 0 MPa. The results of this study will enable engineers to develop a pump defect detection algorithm that is based on an analysis of current, and this algorithm will facilitate the execution of a program that will control a fire pump defect detection system.

• Journal of Chest Surgery
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• v.17 no.4
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• pp.574-586
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• 1984

Although corticosteroid have been shown to stabilize lysosomal membranes and prevent release of hydrolytic enzymes, the mechanism of membrane stabilization remains obscure. This study described functional assessment of efficiency of methylprednisolone in GIK solution by using a isolated Rat Heart Model. Isolated rat heart were subjected to a 2-minute period of coronary infusion with a cold GIK or methylprednisolone mixed cold GIK solution immediately before and also at the midpoint of a 60-minute period of hypothermic [$10{\pm}1^{\circ}C$] ischemic arrest. The result of this were as follow: 1.Spontaneous heart beat after ischemic arrest occurred 11 second later after Langendorffs reperfusion in the methylprednisolone mixed GIK group and 14 second later in the control group. 2.The percentage of recoveries of heart rate at 30 minute after postischemic working heart perfusion was 88.6\ulcorner.6% in the methylprednisolone mixed GIK group. This percentage of recovery was not significantly greater than the control group. 3.The percentage of heart function at 30 minute after postischemic working heart perfusion were; peak aortic pressure $90.8{\pm}4.5%$ coronary flow $87.5{\pm}1.45$ and aortic flow $74.9{\pm}11.8%$ in the methylprednisolone mixed GIK group. This percentage of recovery was significantly greater than the control group. [p<0.05]

• Journal of Chest Surgery
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• v.13 no.4
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• pp.321-337
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• 1980

The increasing use of cardioplegic solution for the reduction of ischemic tissue injury requires that all cardiplegic solution be carefully assessed for any protective or damaging properties. This study describes functional, enzymatic and structural assessment of the efficiency of three cardioplegic solutions (Young & GIK, Bretschneider, and $K^{+}$ Albumin solution) in a Modified Isolated Rat Heart Model of cardiopulmonary bypass and ischemic arrest. Isolated rat heart were subjected to a 2-minute period of coronary infusion with a cold cardioplegic or a noncardioplegic solution immediately before and also at the midpoint of a 60-minute period of hypothermic ($10{\pm}1$. C) ischemic cardiac arrest. The results of this study were as follow: 1. Spontaneous heart beat after ischemic arrest occured 16 seconds later after Langendorff reperfusion in the Young & GIK group (n=6), and 40 second later in the Bretschneider group (n=6) and 6 minute later in the $K^{+}$ Albumin group (n=6), and 16 minute later in the control group (non-cardioplegia). A good recovery state of spontaneous heart beat was shown in the Young & GIK and Bretschneider groups. 2. The percentage of recorveries of heart function at 30 minute after postischemic working heart perfusion were : heart rate $91.6{\pm}3.1$% (P<0.01)m oeaj airtuc oressyre $83{\pm}3$% (P<0.01), coronary flow $70{\pm}8$% (P<0.05) and aortic flow flow rate $39{\pm}9.3$% (P<0.05) in the Young & GIK group. This percentage of recoveries of the Young & GIK group was significantly greater than the control group. In the Bretschneider group, the percentage of recoveries were : heart rate $87.8{\pm}7.5$%(P<0.05), peak aortic pressure $71{\pm}2.3$% (P<0.05) and aortic flow rate $33.2{\pm}6.6$%(P<0.05). hte percentage of recoveries were significantly greater than in the control group. In the $K^{+}$ Albumin group, recoveries of heart function were poor. 3. Total CPK leakage was $131.2{\pm}12.75$IU/30 min/gm. dry weight in the control group, $50.65{\pm}12.75$IU in the Young & GIK gruop, $69.40{\pm}32.21$Iu in Bretschneider group, and $103.65{\pm}15.47$IU in the $K^{+}$ Albumin group during the 30 minute postischemic Langendorff reperfusion. Total CPK leakage was significantly less (P<0.001) in the Young & GIK group, than in the control group. 4. Direct correlatin between percentage recovery of aortic flow rate and total amount of CPK leakage from Myocardium was noticed.(Correlation Coefficient r = 0.76, P<0.001). 5. Mild perivascular edema was the only finding of light microscopic study of myocardium after 60 minute ischemic arrest with cold cardioplegic solutions and hypothermla.

• Journal of computational fluids engineering
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• v.18 no.4
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• pp.82-89
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• 2013

Database of a bleed model has been corrected and numerical simulations have been performed to control buzz using the corrected bleed model. The existing bleed model, which was developed as a part of a boundary condition model for porous bleed walls, underestimates bleed flow rate because flow accelerations near the bleed regions are ignored. Also, it overpredicts the sonic flow coefficient when the bleed plenum pressure ratio is high. To correct these problems, and to enhance the performance of the bleed model, the database has been corrected using CFD simulations to compensate for the flow acceleration near the bleed region. Futhermore, the database of the bleed model is extended with the second order extrapolation. The corrected bleed model is validated with numerical simulations of a shock-boundary layer interaction problem over a solid wall with a bleed region. Using the corrected bleed model, numerical simulations of supersonic inlet buzz are performed to find the deterrent effects of bleed on buzz. The results reveal that bleed is effective to prevent buzz and to enhance the inlet performance.

• Physical Therapy Korea
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• v.22 no.1
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• pp.19-29
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• 2015

Impaired respiratory function is common in patients with stroke. The purpose of this study were to investigate the effectiveness of exercises and to assess forced vital capacity and peak cough flow after completion of neck stabilizing and respiratory reeducation exercises (combining diaphragmatic breathing and pursed-lip breathing exercises). The 45 participants were randomly assigned to an experimental group 1 ($n_1=15$), experimental group 2 ($n_2=15$), and a control group ($n_3=15$). All subjects performed conservative physical therapy for 30 minutes. Experimental group 1 undertook the neck stabilizing exercise and the respiratory reeducation exercise. Experimental group 2 undertook the respiratory reeducation exercise. Additional exercise did not exceed 30 minutes, five times a week for six weeks. The subjects were assessed for deep neck flexor thickness and breathing function (forced vital capacity, forced expiratory volume at one second, forced expiratory volume at one second/forced vital capacity, peak expiratory flow, and manual assisted peak cough flow) at pre-post value. The results of this study were as follows. Experimental group 1 showed a significant increase only in deep neck flexor thickness change rate (p<.05). All groups showed significant increases in forced vital capacity, forced expiratory volume at one second, and peak expiratory flow in pre-post measurement (p<.05). Experimental groups 1 and 2 showed an increase in manual assisted peak cough flow in pre-post measurement (p<.05). There was no significant difference between experimental group 1 and experimental group 2, but experimental group 1 improved more than experimental group 2 in respiratory function as a whole. In conclusion, these findings suggest that the neck stabilizing exercise in combination with the respiratory reeducation exercise can improve forced vital capacity and peak cough flow in patients with stroke.