• Korean Journal of Adult Nursing
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• v.21 no.3
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• pp.349-354
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• 2009

Purpose: The purpose of this study was to determine core nursing intervention in nursing records and to compare perceived nursing intervention priority and nursing intervention frequency of general surgery department. Methods: Subjects were 70 nurses who work in the general surgery department. Data was collected using a nursing intervention classification and analyzed by frequency and mean. Results: The most frequent nursing interventions of nursing records were orderly risk management, coping assistance, tissue perfusion management, skin/wound management and nutrition support. Important nursing interventions were tissue perfusion management, respiratory management, electrolyte acid-base management, elimination, peri-operative care. The most frequent nursing interventions were drug management, peri-operative care, risk management, tissue perfusion management, patient education. Conclusion: This study found that nursing records were different from intervention priority and nursing frequency. So further study is needed for finding focused intervention of specific subjects and differences with priority of nursing and frequency of nursing.

• Proceedings of the KSR Conference
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• 2009.05a
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• pp.2030-2037
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• 2009

In this paper, the study on the allocation of dedicated radio frequency for the radio communication based CBTC system is performed. The dedicated bandwidth for the the private use in railroad is figured out and the allocatable frequency band, which should be investigated hereafter, is proposed. The result of this study provides the basis to present the requirement of dedicated railroad radio frequency and can be used as an important material for the frequency allocation. Furthermore, it is expected that the result can be contributed to the development on railroad radio communication.

• The Transactions of the Korean Institute of Power Electronics
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• v.21 no.2
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• pp.150-159
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• 2016

This paper presents a study on the design optimization of a 5 kW plasma discharger for driving plasma reactor. The proposed study is composed of a high-frequency inverter based on the full-bridge circuit using soft switching techniques for high-frequency switching. The switching frequency in the operating region is the area of 130-200 kHz. By applying the LC resonance technique and a variable switching frequency, control technique is designed to be stable under changes in the load characteristics of the plasma reactor. This paper presents a quantitative analysis technique for design optimization. Experiments are performed according to load characteristic variations depending on the vacuum of the plasma reactor. This paper has verified the topology and design method for the 5 kW plasma discharger design.

• Proceedings of the Korea Water Resources Association Conference
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• 2010.05a
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• pp.581-585
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• 2010

This study introduced a Bayesian based frequency analysis in which the statistical trend seasonal analysis for hydrologic extreme series is incorporated. The proposed model employed Gumbel and GEV extreme distribution to characterize extreme events and a fully coupled bayesian frequency model was finally utilized to estimate design rainfalls in Seoul. Posterior distributions of the model parameters in both trend and seasonal analysis were updated through Markov Chain Monte Carlo Simulation mainly utilizing Gibbs sampler. This study proposed a way to make use of nonstationary frequency model for dynamic risk analysis, and showed an increase of hydrologic risk with time varying probability density functions. In addition, full annual cycle of the design rainfall through seasonal model could be applied to annual control such as dam operation, flood control, irrigation water management, and so on. The proposed study showed advantage in assessing statistical significance of parameters associated with trend analysis through statistical inference utilizing derived posterior distributions.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.21 no.10
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• pp.1262-1272
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• 1997

An experimental study on the frequency control of an inverter heat pump to get the desired indoor room temperature has been conducted for the performance characteristics during the steady, 4, 8, and 16 step frequency operations. The heat pump model used in this study was operated to meet the experimental conditions of ASHRAE standard. The performance of the system was tested by measuring the temperature and pressure of the refrigerant, and cooling capacity, power consumption, etc. of the system. As the controlling frequency steps increased, the running time of the compressor increased as well as the electric consumption of the system and the cooling energy due to the wall heating load. However, the average cooling COP was improved.

• Journal of Electrical Engineering and Technology
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• v.10 no.4
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• pp.1597-1609
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• 2015

This paper introduces the fundamentals of the conventional LC low-pass filter circuit in the fractional domain. First, we study the new fundamentals of fractional-order LC low-pass filter circuit including the pure real angular frequency, the pure imaginary angular frequency and the short circuit angular frequency. Moreover, sensitivity analysis of the impedance characteristics and phase characteristics of the LC low-pass filter circuit with respect to the system variables is studied in detail, which shows the greater flexibility of the fractional-order filter circuit in designs. Furthermore, from the filtering property perspective, we systematically investigate the effects of the system variables (LC, frequency f and fractional orders) on the amplitude-frequency characteristics and phase-frequency characteristics. In addition, the detailed analyses of the cut-off frequency and filter factor are presented. Numerical experimental results are presented to verify the theoretical results introduced in this paper.

• Journal of the Korea Institute of Military Science and Technology
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• v.17 no.5
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• pp.629-636
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• 2014

In the proposed paper, we designed low phase noise frequency synthesizer for Ku-band. The proposed up-mixing frequency synthesizer consists of narrow local oscillation part and variable frequency oscillation part. To improve the phase noise of frequency synthesizer, we analyze how the configuration of frequency synthesizer affect the phase noise. The implemented frequency synthesizer reduce the phase noise. The phase noise is -95.18dBc/Hz at 7kHz frequency offset in 16GHz and -94.27dBc/Hz at 7kHz frequency offset in 16.125GHz.

• 한국정보통신설비학회:학술대회논문집
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• 2008.08a
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• pp.437-440
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• 2008

In this paper, we present and analyze a robust frequency offset estimation scheme for orthogonal frequency division multiplexing (OFDM) systems over radio communication channels. When there exists frequency offset, the loss of orthogonality occurs and the interference problem among several subcarriers in OFDM signals is introduced. The guard interval of OFDM signals is employed for estimating the frequency offset. Furthermore, in order to enhance the frequency offset estimation performance, a ternary sequence is utilized. A frequency offset is estimated based on the synchronized correlator output. The proposed frequency offset estimation scheme can be applied to track the carrier frequency offset of OFDM systems.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 2002.10b
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• pp.283-284
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• 2002

Ball bearings (BB) are generally used in spindle of‘ disk drives at present, but they have been known that BB generate high frequency vibration. Fluid dynamic bearings (FDB) having high-rotational accuracy and small vibration characteristics have been developed as next generation spindles. Especially. a ferro fluid bearing (FFB) spindle has the advantage to prevent leakage and dispersion of lubricating oil using a ferro seal. In this study, we measured damping characteristics and frequency characteristics of these bearing spindles using a high-frequency vibration base. High frequency excitation was added to these bearing spindles mounted on the vibration base, and we proved that FFB and FDB spindles have effective damping.

• Smart Structures and Systems
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• v.14 no.6
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• pp.1197-1220
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• 2014

Accurate actuator tracking is critical to achieve reliable real-time hybrid simulation results for earthquake engineering research. The frequency-domain evaluation approach provides an innovative way for more quantitative post-simulation evaluation of actuator tracking errors compared with existing time domain based techniques. Utilizing the Fast Fourier Transform the approach analyzes the actuator error in terms of amplitude and phrase errors. Existing application of the approach requires using the complete length of the experimental data. To improve the computational efficiency, two techniques including data decimation and frequency decimation are analyzed to reduce the amount of data involved in the frequency-domain evaluation. The presented study aims to enhance the computational efficiency of the approach in order to utilize it for future on-line actuator tracking evaluation. Both computational simulation and laboratory experimental results are analyzed and recommendations on the two decimation factors are provided based on the findings from this study.