• Journal of Environmental Health Sciences
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• v.32 no.3
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• pp.215-221
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• 2006

This study investigated the inactivation of the total coliform, an indicator organism in chlorine dioxide, in order to assess the optimal disinfection procedure for drinking water treatment and distribution systems. This research focus on a number of factors, including the dosage of disinfectant, contact time, pH, temperature and DOC. Water samples were taken from the outlet of a settling basin at a conventional surface water treatment system. As the pH increased in the range of pH 6-9, the bactericidal effects of disinfectants decreased. Changes in levels of pH did not significantly after the disinfection effect of chlorine dioxide for total coliform. With an increase in temperature, there was a subsequent increase in the bactericidal effects of disinfectants. Thus, it is evident that a decrease in temperature will higher the CT values required to inactivate coliform for during the winter. DOC addition can also reduce total coliform inactivation. DOC is the most significant variable in total coliform inactivation with chlorine dioxide.

• Journal of Advanced Marine Engineering and Technology
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• v.35 no.8
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• pp.1105-1110
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• 2011

This paper presents an improved direct torque control based on artificial neural networks technique. The major problem that is usually associated with DTC drive is the high torque(speed) ripple. To overcome this problem a torque hysteresis band with variable amplitude is proposed based on artificial neural networks. The artificial neural networks proposed controller is shown to be able to reducing the torque(speed) ripple and dependency on motor parameter and to improve performance DTC especially at high speed and reversal running.

• Journal of the korean Society of Automotive Engineers
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• v.7 no.4
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• pp.49-56
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• 1985

This study consists of instrumenting and running tests on variable compression engines and measuring the following combustion characterics: (a)flame speed, (b) emission and (c)performance parameter such as power and economy. The results were as follows: 1) The phase separation diagram of substitute fuels were obtained from phase separation experiment. 2) The flame propagation speed of substitute fuels were higher than gasoline and increased with increasing methanol weight percent of substitute fuels. 3) BEMP of substitute fuels was slightly less than that of gasoline but in the range of small weight percent, BEMP was compatible to gasoline. 4) Concentration of NOx decreased significantly with delaying spark advancing time. Also, it decreased for rich equivalence ratio but increased with high compression ratio. In general, NOx concentration was much lower than that of gasoline. 5) Concentration of HC and CO increased for rich equivalence ratio. Also it was lower than that of gasoline.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.06a
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• pp.1087-1090
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• 2005

In precision machinery systems for medical and chemical applications, micropumps with a low pulsation have been demanded and investigated for accurate delivery of a small amount of liquid. This study proposes sheet type check valves instead of ball type check valves for PZT pumps and performs some tests on dynamics characteristics of check valves having different design parameter with variable frequency. The selected materials of check valves is NBR, PP film, Polyimide and Stainless steel(SUS304). In the experiment, dynamic characteristics of stainless steel thin plate have better performance than others.

• Journal of Chest Surgery
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• v.17 no.1
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• pp.59-66
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• 1984

After open heart surgery, the patient must be carefully observed and adequately managed for his survival. This report reviewed 10 cases of ventricular septal defect and 12 mitral valvular diseases as hemodynamics early after open heart surgery. For postoperative 24 hours, clinical status was evaluated for left atrial pressure, central venous pressure,DP[LAP-CVP], peak systolic pressure, heart rate, urine amount, and other clinical findings. Especially, on postoperative fourth hour, cardiac output was most decreased, when the changes of monitoring were compared with two groups with or without using cardiotonics. Finally, we concluded as followings; 1.Postoperatively, variation of CVP was noted in VSD, but mitral valvular disease was more variable change of LAP. 2.DP was 1.3\ulcorner.4 cmH2O in VSD, and 6.4\ulcorner.2 cmH2O in mitral valvular disease. 3.Parameter using cardiotonic was CVP in VSD, and LAP in mitral valvular disease.

• New & Renewable Energy
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• v.3 no.4
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• pp.22-30
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• 2007

An expansion device plays an important role in optimizing the heat pumps by controlling refrigerant flow and balancing the system pressures. Conventional expansion devices are being gradually replaced with electronic expansion valves due to increasing focus on comfort, energy conservation, and application of a variable speed compressor. In addition, the amount of refrigerant charge in a heat pump is another primary parameter influencing system performance. In this study, the flow characteristics of the expansion devices are analyzed, and the effects of refrigerant charge amount on the performance of the heat pump and the variation of compressor speed are investigated at various operating conditions. Mass flow rate through capillary tube, short tube orifice, and EEV was strongly dependent on the upstream pressure and subcooling. The heat pump system is very sensitive with a variation of refrigerant charge amount. The performance of it can be optimized by adjusting the flow rate through expansion device to maintain a constant superheat at all test conditions.

• Proceedings of the KIEE Conference
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• 1991.07a
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• pp.552-554
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• 1991

In this paper is applied Sliding Mode method to position control system with Permanent Magnetic Synchronous Motor (PMSM), with realized a Digital Controller with Micro-Processor. And also, this paper proposes an Algorithm to compen-sate chattering of torque current to added controled parameter to continuous function of torque current.

• Journal of the Korean Society for Industrial and Applied Mathematics
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• v.13 no.4
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• pp.237-245
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• 2009

A numerical solution is provided for a jet produced by a flow emerging from a slit at the bottom corner of a quarter plane. The flow is characterized by the Froude number F, based on the net volume flux and the width of the slit. We perform the free-surface flow for various values of F and another parameter corresponding to the position of the vertical wall. A jet with back-flow near the edge of the vertical wall is obtained, and the limiting case is a jet with a stagnation point.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.24 no.10B
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• pp.1852-1860
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• 1999

This paper studied performance of the AAL2 for variable rate real time services in ATM network with discrete-time simulation model. In this simulation, input parameters are packet fill delay for AAL2 PDU generation, guard time for ATM cell generation, burstness and number of channels. Though variation of the above mentioned parameters, we obtained end-to end delay variations and throughput, analyzed performance effect of the each parameter for voice packet service.

• Magazine of the Korean Society of Agricultural Engineers
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• v.18 no.1
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• pp.4071-4078
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• 1976

The authors analyzed the seepage by means of the following mathmatical solutions of the Laplace Equations on the given boundary conditions. The boundaries of the flow region are of two types i) impervious boundaries (${\Phi}$=constant), and ii) reservoir boundaries (${\Phi}$=constant). The corresponding w plane, bounding the flow region, is the rectangle in Fig. 8-a. As the z plane and w plane are both polygons, by means of the Schwarz-Christoffel transformation the flow region in each of these planes can be mapped con for mally onto the same half of an auxiliary t plane, there by yielding, say, the functions z=f1(t) and w=f2(t). Then, either by eliminating the variable t or by using t as a parameter, the function w=f(z) can be established.