• Proceedings of the IEEK Conference
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• 1998.10a
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• pp.43-46
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• 1998

The performance of a receiver that empolys a multi-stage inter-ference cancellation scheme for uplink fading channel is analyzed when there is carrier frequency offset. And the conditions to permit the performance improvement are analytically obtained. Numerical results show the effectiveness of the proposed system under Rayleigh fading channel assuming that carrier frequency offset is present.

• Health Policy and Management
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• v.18 no.4
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• pp.111-124
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• 2008

New ways of work-shift and learning programs, which were based on the concept of 'performance improvement through people', have been introduced to healthcare organizations. I analyzed the performance of the changes and the performance differences. Data were collected through interview and survey. I discussed that modification of management practices which were developed in manufacturing organizations is important for successful implementation in healthcare organizations.

• Journal of Positioning, Navigation, and Timing
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• v.4 no.4
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• pp.187-193
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• 2015

A maritime Differential Global Positioning System (DGPS) reference station broadcasts correction information to users having a DGPS receiver so that the navigation performance can be improved. A maritime DGPS reference station consists of a reference station (RS) that generates and broadcasts correction information, an integrity monitor (IM) that monitors the integrity of correction information, and a control station (CS) that controls them. A maritime DGPS reference station is continuously operated for 24 hours, and thus improvement in the ease of operation is a major element that can improve the performance of the system. In this study, a configuration of a maritime DGPS reference station that can improve the ease of operation and a relevant protocol were proposed, and an example of the implementation of the proposed system was presented.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.36 no.5
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• pp.352-359
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• 1987

The cycloconverter operating on a circulating current-free mode has many zero crossing points. If an exact zero crossing points are not detected, the three phase-unbalanced currents will flow in a motor. In this paper, the current feedback using a current reference wave is proposed to improve the problems of zero crossing detection, three phase-unbalanced voltages, currents, and torgue ripples. To prevent the saturation of the air gap flux and keep the torque constant, the constant voltage / hertz control with IR compensation is adopted. The PI-controller is designed using the linearized model of the cycloconverterinduction motor system. Alsi, Z-80A single board computer has been used to implement the proposed scheme which results in the performance improvement of cycloconterter-fed induction motor speed control system.

• Journal of Advanced Marine Engineering and Technology
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• v.29 no.7
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• pp.744-749
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• 2005

This paper describes the performance improvement of power control system of magnetron (MGT) for microwave oven. The MGT is used extensively in household microwave oven and industrial microwave heating devices, and is operated by 3.0[kV] $\∼$5.0[kV] dc high voltage. The proposed power supply is consisted of a bridge rectifier, step-up converter(SUC) and its controller, half bridge inverter(HBI) and its controller, and full wave double voltage rectifier(DVR). In the proposed system, a good power factor can be obtained by the SUC' switching method that the inductor current waveforms follows that of the rectified voltage, and a line input power can be controlled to a range of 17.5[$\%$] by duty ratio (DR) adjustment of the HBI.

• Proceedings of the KIEE Conference
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• 1999.11c
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• pp.821-823
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• 1999

This paper describes a study on a person identification system which can improve currently available biometric systems. In the procedure of PIN(Personal Identification Number) input, holding time, interkey time between key presses are measured and normalized. Person identification is performed by matching using Euclidean distance of these punching dynamics. The experimental results show the possibility of improvement of the overall system performance when keypad dynamics feature is applied to the biometric systems which take PIN input using keypads.

• Transactions of the Korean hydrogen and new energy society
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• v.21 no.3
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• pp.220-226
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• 2010

The heat transfer performance improvement in closed cooling water system of an electric power generation can be achieved by a corrosion control using corrosion inhibitors. The effect of trisodium phosphate and sodium nitrite upon carbon steel at various $Cl^{-1}$ ion containing water concentrations was examined by an integrated corrosion monitoring system. Nitrite was found to be the most effective inhibitor among tested inhibitors for carbon steel. The inhibiting process is considered as adsorption of nitrite ions in oxide layer which form a passive film on the carbon steel surface.

• The Transactions of the Korean Institute of Power Electronics
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• v.17 no.1
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• pp.57-66
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• 2012

This paper proposes a performance improvement of grid-connected inverter system using sliding-mode based direct power control with a variable gain. The proposed control method determine variable gain of PI controller by using modeling at direct power control (DPC) applied to space vector modulation method. Also, this method use sliding-mode control to maintain excellent dynamic response of character of direct power control (DPC). The validity of the proposed algorithm are verified by simulations and experiments.

• Korean Journal of Air-Conditioning and Refrigeration Engineering
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• v.22 no.8
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• pp.530-537
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• 2010

With the advancement of technology, the density of IT equipment, heat load and power consumption continue to increase in high density internal-load dominated buildings as datacenters. To improve the HVAC system's energy performance and efficiency, there is a need to find methods of using outside air. Through cooling tower control that is based on outside wet-bulb temperature, the water-side economizer made it possible to achieve a maximum energy performance improvement of about 16.6% over the basic chilled water system, whereas the air-side economizer, through control based on outdoor air enthalpy, made it possible to achieve about 42.4% improvement.

• Journal of the military operations research society of Korea
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• v.28 no.2
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• pp.1-19
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• 2002

This study shows the effect of inventory policy change from supplier-based to customer-based. We focus on the service level, cost, and information distortion of the Military Supply Chain(MSC) with System Dynamics. We design MSC model according to field practician interviews by using Vensim. The simulation makes a comparison between supply-based inventory policy performances and order-based inventory policy performances. In order to evaluate the MSC performances, we measure the accumulation of backlog(service level), supply chain cost, and order percentage overshoot(information distortion). The results show that 1) changing inventory policy from supplier-based to end customer order-based gets a good customer service, reduces MSC cost, and prevents information distortion, 2) changing inventory policy from supplier-based to immediate customer order-based reduces a small amount of MSC cost and deteriorates customer service, and 3) supply level is main factor for MSC performances improvement. This study implicates the policy change makes a improvement of MSC performance without introducing information system.