• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.1450-1454
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• 2000

In order to understand dynamic characteristics of centrifugal compressor supported foil bearing, of which normal operating speed is about 20,000 ${\sim}$ 50,000 rpm, the rotor whirl is measured using gap sensors. Not only critical speeds of rotor system but also stability of rotor whirl, which are main concerns of the turbo compressor system, are measured using gap sensors by varying the rotating speed the rotor. The stiffness characteristics of bearing system is shown to be almost invariant according to speed variation by the measurement of eccentricity. In addition, from the directional power spectral density function of the measured vibration signal, the isotropy stiffness characteristics of foil bearing system is discussed.

• Proceedings of the KIEE Conference
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• 1994.07a
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• pp.199-201
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• 1994

In this paper, The characteristics of the new superconducting maglev system which has quadruple armature windings is examined. This system can generate guidance force and levitation force as well as propulsion force by single ground coil. The time-domain analysis method and phasor analysis method are derived to analyze the characteristics of the proposed system. From the numerical examples for two kind of armature winding configurations, it is shown that the levitation force and guidance force can be generated by single armature winding of the linear synchronous motor without any other ground coils for levitation and guidance, and that double layer configuration has better characteristics in the qualitive characteristics. like as efficiency, pulsation of the electromagnetic forces and drag ratio, than the single layer configuration.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.6
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• pp.23-29
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• 2004

This work was conducted to figure out the atomization characteristics of three types of bio-diesel fuels using a common-rail injection system. The process of spray development was visualized by using a spray visualization system composed of a Nd:YAG laser and an ICCD camera, The spray tip penetrations were analyzed based on the frozen images from the spray visualization system. On the other hand, the microscopic atomization characteristics such as the distributions of SMD and axial mean velocity were measured by using a phase Doppler particle analyzer system, It is revealed that the sprays of the bio-diesel fuels have larger SMD than that of diesel fuel mainly due to high viscosity of bio-diesel. Different characteristics of bio-diesel fuels were also measured in spray tip penetrations according to the fuels and mixing ration.

• Journal of the Semiconductor & Display Technology
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• v.8 no.1
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• pp.7-12
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• 2009

The outgassing effects of selected vacuum materials on the vacuum characteristics were simulated by the $VacSim^{Multi}$ simulation tool. This investigation examined the feasibility of reliably simulating the outgassing characteristics of common vacuum chamber materials (aluminum, copper, stainless steel, nickel plated steel, Viton A). The optimum design factors for these vacuum systems were suggested based on the simulation results. The baking-out effects of the modeled systems and materials on the performance of the vacuum system were also analyzed. The simulation predicted that the overall outgassing effect was more significant in the TMP system than in the DP system and that the utilization of a booster pump has a greater effect on the evacuation time than on the ultimate pressure.

• Korea Journal of Hospital Management
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• v.4 no.1
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• pp.66-95
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• 1999

This study was conducted to analyze the medical charges of the elderly dementia inpatients, to identity their characteristics, and there by to evaluate feasibility of the per diem payment system for the patients. Data on medical charges of the patients were collected from the National Federation of Medical Insurance and sample hospitals from October through December 1997. The data were analysed in order to find the characteristics and test hypotheses postulated. The results are summarized as follows; Firstly, there was no difference statistically in between disease groups and between the dementia inpatients belonging to each disease group. Secondly, the amount of the non-insurance medical charges of the elderly dementia inpatients is considerably high compared to the insurance medical charges paid by the patient, which implies that some measures are to be prepared by the Government. Finally, medical charges per inpatient day of the dementia patients are not different statiscally by sex, by age group, and by disease group. This result supports the feasibility of the per diem payment system for the elderly dementia inpatients.

• Proceedings of the KIEE Conference
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• summer
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• pp.815-817
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• 2004

This paper deals with the characteristics analysis and experiments of operating actuator for automatic door operated by fire detecting sensor. The dynamic characteristics of operating actuator system are analyzed on the structure of the operating actuator model. Simulation and experimental result have been performed for the verification of the proposed system and dynamic characteristics applied to a actuator by electromechanical energy conversion theory. The experimental result have been compared with proposed theoretical predictions. In this experimental result represented the temperature T1 and T2 which remarks T1 is a circumstance of operating actuator system, and T2 is a fire detecting sensor part.

• Transactions of the Korean Society of Automotive Engineers
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• v.12 no.1
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• pp.190-195
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• 2004

An exhaust brake system is composed of a gate valve, a pneumatic cylinder and an on-off solenoid valve. An on-off solenoid valve which is a key component of the exhaust brake system ought to have characteristics such as high reliability and long life for reducing the foot brake and tires damage, and for driver's fatigue relief of middle/large size vehicles running a long distance. In this paper, an on-off solenoid valve which is used for vehicle brake system was studied. For the performance evaluation of the on-off solenoid, electromagnetic characteristics and dynamic characteristics are analyzed. On the basic study for the performance improvement of exhaust brake system, pneumatic circuit and pneumatic valve of on-off solenoid type were suggested and the performance of pneumatic valve through the test procedure was evaluated.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.43 no.1
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• pp.38-48
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• 2007

Numerical modeling was used to evaluate the submerging characteristics of the submersible fish cage system operated by compressed air. The submerging characteristics calculated by numerical analysis as the cage was moved up and down were nearly identical to existing experiment results. Thus, the numerical model proposed in this study could be very useful in analyzing various parameters required for optimizing the design of a submersible fish cage system operated by compressed air.

• Journal of Power System Engineering
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• v.19 no.2
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• pp.84-89
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• 2015

The occurrence of algae caused by eutrophication of fresh water is a pollution source to destroy the aquatic environment. When the high voltage electric field is applied in the water, When a high voltage is applied to the electric field in the water, the algae can be broken the balance of cell membranes, and is dead. In this paper, we develop a water quality improvement system for generating an electric field having a higher energy than the zeta potential when a high voltage is applied to 4,000V. To ensure the mobility of the water quality improvement system, we designed the PV generation system using the optimal size technique that is based on the model of power lack ratio. By evaluating the output characteristics of the water quality improvement system, power generation characteristics of the PV generation system, and battery charging characteristics, we can show that the proposed system can be applicable to the water quality improvement system inhibiting the growth rate of the algae in the fresh water.

• Journal of Biomedical Engineering Research
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• v.4 no.1
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• pp.15-20
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• 1983

In this paper, the velocity characteristics of the vertical saccadic eye movement system with subject-experiment are investigated utilizing the infra-red methed. Especially, target-generation system which produces pseudo-random signals using EPROM 2716 and differentiator whose time constant is 12 msec are developed in hardware.