• The KSFM Journal of Fluid Machinery
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• v.18 no.2
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• pp.22-28
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• 2015

The primary design goal of a compressor is focused on improving efficiency. Secondary objective is to widen the operating range of compressor. This paper presents a numerical and experimental investigation of the influence of the bleed slot on the operating range for the 1.2 MW class centrifugal compressor installed in a turbocharger. The main design parameters of the bleed slot casing are upstream slot position, inlet pipe slope, downstream slot position and width. The DOE(design of experiment) method was carried out to optimize the casing design. Numerical analyses were done by the commercial code ANSYS-CFX based on the three dimensional Reynolds-averaged Navier-Stokes equations. Results showed that efficiency and pressure ratio increased as the downstream slot position and width were smaller and the upstream position was located away from the impeller inlet. Experimental works were also done with and without the bleed slot casing. The simulation results were in good agreement with the test data. Enhancement of both the surge margin up to 26.5% and the pressure ratio with the optimized bleed slot design were achieved, compared with the surge margin of only 6.6% without the bleed slot casing.

• Korean Journal of Adult Nursing
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• v.20 no.3
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• pp.375-385
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• 2008

Purpose: This study is to identify factors affecting on the level of practice on nosocomial infection management of operating room nurses. Methods: The subjects of this study were 155 nurses who worked in operating rooms of six medical centers in located Gwangju and Chonanam area. Data were collected during October, 2006 by the questionnaire including a total of 124 questions. Data collected were analysed with use of SPSS 12.0 program. Results: There was a significant difference of the level of practice by marital status(t=3.957, p=.048), education level(F=3.691, p=.027), position(F=6.588, p=.002), type of hospital(t=4.857, p=.029), number of nurse(F=4.243, p=.007), education about nosocomial infection management(F=3.069, p=.030), management council(t=6.397, p=.012) and management manual(t=6.961, p=.009). There were significant correlations between knowledge and practice (r=.389, p=.000), and between awareness and practice(r=.389, p=.000). Knowledge on nosocomial infection management, awareness of hands washing and positions were affecting factors on the level of practice. Conclusion: This study suggests that knowledge and awareness on nosocomial infection prevention and management of operating room nurses should be improved through consistent education. and support of administrator's of hospitals is needed.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.10 no.2
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• pp.165-172
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• 1998

An experimental study on the heat transfer of the inclined thermosyphon with low integral-fins in which boiling and condensation occurred is performed to investigate its heat transfer performance. Water and CFC-30 have been used as the working fluids. The operating temperature and the inclination angle of thermosyphon have been used as the experimental parameters. The heat flux input and the inclination angle $\theta$ towards the vertical position were varied in steps. The heat transfer rate in the thermosyphon was depended upon the inclination angle. In addition, it is to obtain the overall heat transfer coefficients and the characteristics as a operating temperature for the practical applications.

• 한국정보디스플레이학회:학술대회논문집
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• 2008.10a
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• pp.337-339
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• 2008

Recently, Note PCs have being widely used due to their features such as good mobility and low power consumption. In order to ensure the current market position, further improvement is required. Especially, the lower operating voltage is essential for the long operating time of Note PCs. For the achievement of lower operating voltage, possible contributions from LC materials side are to lower the viscosity and to increase the dielectric constant without sacrificing the reliability. In order to achieve lower driving voltage, new LC mixtures have been developed, optimizing theirs physical properties.

• Proceedings of the KIEE Conference
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• 1999.07b
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• pp.709-711
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• 1999

In this paper, Fuzzy Logic Controller was Designed for the Degree control of Arago's disk system. Arago's disk system is an application of Arago's disk phenomenon which is the operating principle of induction motor. Since the Arago's disk system varies to stable region. maginally stable region, unstable region according to the degree of bar respectively, it is a sutable system which can be evaluate an efficiency of the system. While an existing controller which was designed using linearized system modeling could control the system on only one operating point, fuzzy logic controller has the advantage in showing good response for multi-operating points because it does not need system modeling.

• Journal of Fisheries and Marine Sciences Education
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• v.25 no.4
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• pp.998-1007
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• 2013

At container terminals, a major measurement of productivity can be work efficiency. For improving the productivity of container crane, the more efficient container yard operation method is necessary in container terminals. Recently, container terminal operators make an experiment on the dual cycle operation, which ship loading/unloading were carried out simultaneously, for increasing the productivity of container crane. In this paper, propose a system operating efficient dual cycle methods as utilize Ad-hoc technology in distributed port operation system. The dual cycle methods that proposed recognizes position information of Y/T during an action in Ad-hoc networks in case of container transfer works by real time as load an Ad-hoc module to Y/T taking charge of a container transfer with quay and yard. Utilize Ad-hoc networks technology in an operating system of container yard, and efficiently distributed processing done Y/T to container crane compare with operation systems of the existing dedicated method, and an improvement can do an operating system of an yard.

• Journal of the Semiconductor & Display Technology
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• v.16 no.3
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• pp.25-30
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• 2017

Arago's disk system consists of a speed controller of the DC motor (inner loop controller) and a position controller of the magnetic bar angle (main controller), which are implemented by the design of the PI and PID controller, respectively. First, we analyzed the nonlinear characteristics of the Arago disk system and found the operating point range of three locations as a result. In this paper, a gain scheduler method was applied to guarantee a constant control performance in the range of $0{\sim}130^{\circ}C$, and a structure to change the controller according to the control reference value based on the previously obtained operating points was experimentally implemented. The Distributed Control Systems (DCS) configuration using the Controller Area Network (CAN) was used to verify the proposed method by improving the operational efficiency of the entire experimental system. So, simplicity of the circuit and easy diagnosis were achieved through a single CAN bus communication.

• Proceedings of the KSME Conference
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• 2004.11a
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• pp.708-713
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• 2004

This research develops a sensorless hydraulic servo system of Parallel-Typed robot for harbour construction. Purpose of the robot is to mechanize the construction, which is accomplished through a joystick's operating by a stoneworker (or diver). The robot is attached on the end of an excavator as its attachment or transported by a crane to reach the desired place. The embedded compact controller is installed on the robot body and controlled by wireless telecommunication. For underwater work, it is necessary to waterproof the robot and its sensors. Especially, a sensor waterproof is a main drawback for the underwater robot. This leads us to develop a hydraulic robot position controller using an observer which gives the position information without any position sensor. We design a neural network to identify the displacement change according to the command voltage to servo valve. To verify the sensorless controller, this paper presents the performance of the sensorless control for which the position is given by the observer comparing with that of the sensor control for which the position is measured by LVDT sensors.

• Journal of Institute of Control, Robotics and Systems
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• v.20 no.9
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• pp.914-921
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• 2014

In this paper, an algorithm is suggested to detect an offset angle of the absolute rotor position sensor after the initial assembly of a PMSG. Unlike previous studies in a stationary state, this one is not designed to detect an electrical angle but rather the absolute position of the rotor is detected while operating the generator. Also,a position sensor, current sensors and voltage sensor were used to ensure reliability. This technique completes the detection of the sensor offset in two steps. In the first step, a zero-crossing of the EMF is measured using a voltage sensor to detect the electrical angle offset when the alternator is actuated by the engine. In the second step, a high frequency current is injected along the d-axis on-line during the control of the generation, eventually to obtain the inductance using a DFT (Discrete Fourier Transform), and then to ultimately extract the final electrical angle offset through the comparison of the inductance magnitude. The suggested algorithm was validated with PSIM simulation and, furthermore, was tested with actual experiments on a dynamometer.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2006.11a
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• pp.294-297
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• 2006

The rail clamp is the device to prevent the crane slips along a rail from the wind blast as well as to locate a container crane in the set position during an operating mode. In this study we conduct the research for determining the proper position of supporter to prevent the overload applied to the rail clamp with respect to the wedge angle in the wedge type rail clamp. The friction force between the jaw pad and the rail to prevent that the crane slips along a rail, when the wind blows, is generated fly the rail-directional wind load. Accordingly the proper position of the supporter to prevent the overload is determined fly analyzing the forces applied to the rail clamp in the wedge working stage. In order to analyze the effect of the wedge angle on the position of supporter, 5-kinds of wedge angles, such as 2, 4, 6, 8, $10^{\circ}$, were adapted as the design parameter, and the wind speed of 40m/s was adapted as the design wind speed criteria.