• The Journal of Korean Medicine
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• 제33권4호
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• pp.50-59
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• 2012

Objectives: This study aimed to compare the effects of high frequency electroacupuncture, low frequency electroacupuncture and manual acupuncture on the autonomic nervous system in stroke patients by using a heart rate variability measuring device. Methods: Thirty-nine participants were recruited and each participated in the high frequency electroacupuncture group, low frequency electroacupuncture group, manual acupuncture group and non-acupuncture group. Some participants received needle insertion with 100 Hz stimulation, with 2Hz stimulation and manual stimulation under mental arithmetic stress during 2 sections. Other participants maintained in the supine position without acupuncture under mental arithmetic stress during the 2 sections. Acupuncture needles were directly inserted perpendicularly to the right Liv 3 acupoint followed by delivery of electric pulses to these points for 8 minutes. Heart rate variability was measured 8 minutes before and 16 minutes after acupuncture stimulation by a heart rate variability measuring system. Results: We found a significant elevated HF total power between 1 section and 2 section and between 1 section and 4 section in the non-acupuncture group, between 3 section and 4 section in the 100Hz electroacupuncture group, and between 1 section and 2 section in the manual acupuncture group and with no change in the 2Hz electroacupuncture group. We also found a significant VLF total power between 2 section and 3 section in the 2Hz electroacupuncture group and between 1 section and 4 section and between 2 section and 4 section in the 100Hz electroacupuncture group. All four groups showed no significant differences in other parameters including heart rate mean, low-frequency power, and the ratio of low-frequency power to high-frequency power. Conclusions: This study may be a basis for research about effects of acupuncture and electroacupuncture because the parameters measured, heart rate variability, showed differences according to acupuncture.

• Journal of Positioning, Navigation, and Timing
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• 제10권4호
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• pp.315-333
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• 2021

Due to the Global Navigation Satellite System (GNSS) modernization, recently launched GNSS satellites transmit signals at various frequency bands such as L1, L2 and L5. Considering the Korean Positioning System (KPS) signal and other GNSS augmentation signals in the future, there is a high probability of applying more complex communication techniques to the new GNSS signals. For the reason, GNSS receivers based on flexible Software Defined Radio (SDR) concept needs to be developed to evaluate various experimental communication techniques by accessing each signal processing module in detail. This paper proposes a novel SDR-based A-GNSS receiver capable of processing multi-GNSS/RNSS signals at multi-frequency bands. Due to the modular structure, the proposed receiver has high flexibility and expandability. For real-time implementation, A-GNSS server software is designed to provide immediate delivery of satellite ephemeris data on demand. Due to the sampling bandwidth limitation of RF front-ends, multiple SDRs are considered to process the multi-GNSS/RNSS multi-frequency signals simultaneously. To avoid the overflow problem of sampled RF data, an efficient memory buffer management strategy was considered. To collect and process the multi-GNSS/RNSS multi-frequency signals in real-time, the proposed SDR A-GNSS receiver utilizes multiple threads implemented on a CPU and multiple NVIDIA CUDA GPGPUs for parallel processing. To evaluate the performance of the proposed SDR A-GNSS receiver, several experiments were performed with field collected data. By the experiments, it was shown that A-GNSS requirements can be satisfied sufficiently utilizing only milliseconds samples. The continuous signal tracking performance was also confirmed with the hundreds of milliseconds data for multi-GNSS/RNSS multi-frequency signals and with the ten-seconds data for multi-GNSS/RNSS single-frequency signals.

• Journal of the Korean Society of Safety
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• 제32권1호
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• pp.33-40
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• 2017

This paper addresses the assessment methods used to evaluate the magnetic exposure of a human to ELF EMF (Extremely Low Frequency Electromagnetic Field) which is caused by the process of power delivery from 60 Hz commercial power. These days the main concern is primarily focused on the magnetic field. For the exposure assessment, both numerical studies and laboratory experiments were studied and the results of the two compared for methodological suitability. The numerical analyses employ the Impedance Method (IM), Boundary Element Method (BEM), and Finite Element Method (FEM) and the laboratory experiments used various human phantom models made with conductivities congruent to human organs and then exposed to uniform/non-uniform magnetic fields to produce eddy currents. Under these conditions a number of examples have been evaluated and the reliability assessed to present the pros and cons of each methodology.

• Proceedings of the KIPE Conference
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• 전력전자학회 2011년도 전력전자학술대회
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• pp.410-412
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• 2011

Magnetic cables that can deliver high frequency AC electric power safely for flammable or sensitive workplaces preventing from arcs and electric shocks are firstly proposed in this paper. To deliver the power for a long distance, several new magnetic cable structures which drastically reduce the parallel leakage flux by appropriate magnetic shield between the magnetic cables are suggested; hence, the output power can be improved more than ten times. The proposed magnetic cables are fully analyzed and verified by simulations and experiments with good agreement. The output power and efficiency for a prototype magnetic cable of 1.5m long and 1 cm gap between parallel cores were measured as 154W and 67 %, where the source current and frequency were 10 A and 20 kHz, respectively.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2009년도 춘계학술대회 논문집
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• pp.274-279
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• 2009

Reduction Gear Box where from productive site uses the gear with power delivery with high mechanical efficiency of power a deceleration and as the mechanical element union product which has the velocity ratio which is various together is produced with the power occurrence motor and leads gets a high driving force is plentifully used. The above occurs from gear drive issue sound Whine, Noise and Vibration as occurring from the rim process which the gear will bite mainly is delivered with the case etc. gear drive whole which leads the axis and the bearing. The productivity falls with the going straight rate decrease which with like this problem point is caused by with rework the problem point where the cost of production rises under improving boil many kinds analyzed the plan and investigates the resultant acceleration sensor which and a frequency analysis system and was made to apply.

• Journal of Korea Society of Industrial Information Systems
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• 제21권4호
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• pp.55-66
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• 2016

In this paper, 99 evaluation factors for website quality were derived from 79 research papers. Among them, 19 factors which are quoted in more than 7 research papers are summarized. The followings show such summarized factors: (1) Reliability (2) Ease of use (3) Design (4) Response time (5) Information Quality (6) Learnability (7) Accessibility (8) Effectiveness (9) Navigation (10) Sensibility (11) Accuracy (12) Contents (13) Aesthetic Impression (14) Completeness (15) Sympathy (16) Security (17) Delivery (18) Interaction (19) Responsibility.

• KIEE International Transactions on Electrophysics and Applications
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• 제5C권4호
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• pp.161-164
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• 2005

Viologen has been extensively investigated in the paper because their well-behaved electrochemistry has led to their use in a variety of theses, including the electron acceptor for the electric charge delivery mediation of the devices. It was formed monolayer in QCM by self-assembly method. We could know the adsorbed mass of viologen molecules from the frequency shift. We calculated that the adsorbed mass was about 196 [$ng/cm^2$]. We studied the electron transfer property of viologen by the cyclic voltammetry among the electrochemical process so we changed an anion like 0.1 M $NaClO_4$ and $Na_3PO_4$ electrolyte solution and investigated the interrelationship between scan rate and peak current when scan rates were increased twice.

• Proceedings of the KIEE Conference
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• 대한전기학회 2007년도 제38회 하계학술대회
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• pp.2020-2021
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• 2007

Viologen derivative has been widely investigated because of their well-electrochemical behavior including the electron acceptor for the electric charge delivery mediation of the devices. The viologen exist in three main oxidation states, namely, $V^{2+}{\rightleftarrows}V^{{\cdot}+}{\rightleftarrows}V^0$. These redox reactions are highly reversible and can be cycled many times without significant side reaction. In this paper, we determined the time dependence to resonant frequency shift of QCM during self-assembly process and the electrochemical behavior of the self-assembled viologen monolayers by electrochemical QCM method. The redox reactions of viologen were highly reversible and the EQCM has been employed to monitor the electrochemically induced adsorption of SAMs during the redox reactions.

• Journal of the Semiconductor & Display Technology
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• 제21권2호
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• pp.32-37
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• 2022

As semiconductors become finer, equipment must perform precise and accurate processes to achieve the desired wafer fabrication requirement. Radio frequency power delivery system in plasma system plays a critical role to generate the plasma, and the role of impedance matching unit is critical to terminate the reflected radio frequency power by modifying the impedance of the matching network in the plasma equipment. Impedance matching unit contains one fixed inductor and two variable vacuum capacitors whose positions are controlled two step motors. Controlling the amount of vacuum variable capacitor should be made as soon as possible when the mismatched impedance is detected. In this paper, we present the impedance matching algorithm using the phase sensor.

• International conference on construction engineering and project management
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• The 6th International Conference on Construction Engineering and Project Management
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• pp.371-375
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• 2015

Design-Build (DB) has gained in popularity in roadway projects due to its defining advantage to improve communication and fast-track project delivery. However, very little is known about the impact of change order frequency and occurrence timing pertaining to DB projects. The study analyzes their impacts on project time and cost performance by conducting a rigorous numerical analysis drawing on 530 3R (rehabilitation, reconstruction, and resurfacing) projects completed between 2002 and 2011 in Florida by using a multiple linear regression. The results indicate that DB outperformed Design-Bid-Build in project cost as well as time. Critically, the regression analysis signifies that earlier change order occurrence caused more unfavorable impacts on schedule and cost. The proposed analyses and models will lead to the improved ability of agencies to quickly and more reliably estimate the potential change order impacts on schedule and cost.