• Journal of Advanced Navigation Technology
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• v.25 no.5
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• pp.363-369
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• 2021

In this paper, We propose variable cut-off frequency and variable sample rate small-area multi-channel digital filter for telemetry system. Proposed digital filter reduced hardware area by implementing filter banks that can variably use cut-off frequency and sample rate without additional filter banks for an arbitrary cut ratio. In addition, We propose the architecture in which sample rate can variably be selected according to the number of filters that pass through the multiplexer control. By using time division multiplexing (TDM) supported by the finite impulse response (FIR) intellectual property (IP) of Quartus, the proposed digital filter can greatly reduce digital signal processing (DSP) blocks from 80 to 1 compared without TDM. Proposed digital filter calculated order and coefficients using Kaiser window function in Matlab, and implemented using very high speed integrated circuits hardware descryption language (VHDL). After applying to the telemetry system, we confirmed that the proposed digital filter was operating through the experimental results in the test environment.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.15 no.5
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• pp.75-84
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• 2015

A data allocation technique is essential to improve the performance of data broadcast systems. This paper explores the issues for allocating data items on broadcast channels to process multiple-data queries in the environment where query profiles and query request rates are given, and proposes a new data allocation scheme named IDAS. The proposed scheme employs the strategy that the broadcast frequency of each data is determined by the square root value of its relative access probability. IDAS could enhance the performance of query response time since it can process queries of high request rate fast and show a resonable degree of query data adjacency. Simulation is performed to evaluate the performance of the proposed scheme. The simulation results show that IDAS outperforms other schemes in terms of the average response time.

• Journal of IKEEE
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• v.20 no.1
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• pp.103-106
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• 2016

PWM buck converters usually use a type-III error amplifier. Since this amplifier has a big capacitor with slow slew rate, they can generate an unintended large overshoot/undershoot at the output when a large load current change occurs. They can also respond slowly by varying the reference voltage. In order to increase battery lifetime, power supplies require a various range of load current and output voltage. PWM buck converter also should have a characteristic of both fast load response and reference tracking. This paper surveys a few recent techniques for reducing the settling time, and discusses their merits and limitations.

• Journal of IKEEE
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• v.21 no.4
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• pp.381-387
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• 2017

Stress at work has become a serious problem affecting many people of different professions, life situations, and age groups. Stress management should start far before the stress start causing illnesses. In this study, studies were conducted to evaluate stress by measuring the Galvanic skin Response(GRS), Electrocardiograph(ECG), and Electroencephalogram(EEG) generated during images and noise stimuli. The GRS amplitude showed that the stress situation was 27.9 % higher than the baseline. And after the stimulus period, the response time of baseline was longer than 71.6 % than the stress situation. The stress response characteristics of the HRV showed that the rate of change in RMSSD was 16.4 %, and the rate of change of the HF Power was 29.7 %. EEG showed that the frequency band was gradually changed to the ${\theta}$ wave band during stress stimulation. We will be able to utilize image stimuli and noise stimuli as an objective indicator of stress and correlation.

• Journal of the Korea Institute of Information and Communication Engineering
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• v.24 no.10
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• pp.1319-1324
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• 2020

A smart tag complements various problems caused by the expansion of the use of existing magnet cards. This emerged as a result of the need for alternative means to perform safer and more diverse functions. RFID tags are becoming increasingly ubiquitous sensor networks and Internet of Things technologies as they give everything an ID, enabling automatic recognition of objects and forming a communication network between them. In this paper, a contactless RFID smart tag reader composed of RFID tags and readers using AVR processor was developed. The system has a low frequency band of 13.56MHz and is designed by PWM method of communication velocity 26.48kbps. The developed RFID smart tag board showed a faster response rate than the typical RFID system as a result of the simulation, and the actual experiment also showed an improvement in response rate.

• The Journal of the Acoustical Society of Korea
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• v.22 no.5
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• pp.418-424
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• 2003

In this paper we analyzed the performance of data transmission using BFSK modulation. The system performances were evaluated by the experiments in water tank. As a result we showed the influences of reverberation due to the multipath. In order to simplify the experiment procedure the channel coding etc. were omitted. The experimental result shows that the maximum transmission data rate in used water tank is about 800 bps. We also verified that the reverberation effect m reduced using a deconvolution with a measured channel impulse response. This method improved the bit rate by about 100 bps than simple noncoherent demodulator at bit error rate of 10/sup -3/.

• Journal of the Korean Institute of Telematics and Electronics
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• v.16 no.5
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• pp.1-11
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• 1979

Since the second half of 1960's one of the information industry's most vital, yet least-well-understood areas has evolved-Data communications/Computer communications. To successfully realize this field we have to identity and reveal a variety of fundermental characteristics of communications channels and see their high reliability as prerequisites. This paper has accumulated related data from 1973 on, systematically analyzed them and provided some basic back ground and suggestions. Error rate which is the final and external characteristics of communication lines according to channal types, communication types and speed, block length and geographical difference between test points was extensively examined as well as their frequency response and d-c characteristics. The perspective of 9600BPS high speed data communications was also discussed.

• The Journal of the Acoustical Society of Korea
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• v.32 no.1
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• pp.22-31
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• 2013

In this paper, we propose a method that estimates the channel response from underwater communication signals with MMSE (Minimun Mean Squared Error) and detects dominant components automatically based on power of response components using CFAR (Constant False Alarm Rate). Statistical characteristics are analyzed with variation of magnitude and phase and time coherence via experimental data obtained by drifting transmitter and receiver. We show that bit error rate has small difference, 1.2 times, compared with the case using every channel information estimated within data period when estimation and equalization is performed with extracted characteristic obtained by the proposed method.

• Quality Improvement in Health Care
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• v.22 no.2
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• pp.75-90
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• 2016

Objectives: This study measures the level of cognition of employee's patient safety culture and evaluates the current level through comparing the results to external levels. Ultimately it is performed to construct a strategic improvement plan through the basic database for patient's safety culture. Methods: A questionnaire survey of self reporting type was carried out using structured questionnaire of the patient's safety culture for employees currently employed in a hospital. Total responders was 1,129 and a response rate was 54.6%. The survey results were calculated with a percent positive response, and the current level was evaluated by comparing with the survey results of a hospital (2009 and 2014) and the survey result of The Agency for Healthcare Research and Quality(2014). Results: Sub-dimension of high percent positive response for each area were 'teamwork within hospital units' (80%), 'feedback & communication about error' (73%) and 'supervisor/manager expectations & actions promoting safety' (67%). Meanwhile, 'teamwork across hospital units' (31%), 'hospital management support for patient safety' (29%), 'staffing' (27%) and 'non-punitive response to error' (17%) were relatively low percent positive response. Compared to the survey results of AHRQ (2014) for each area, 'teamwork within hospital units' (80%), 'feedback & communication about error' (73%), 'frequency of event reporting' (66%) were at the top 50% percentile level and the remaining sub-dimensions showed a very low level in the lower 10% percentile area. Conclusion: In order to establish a system for patient safety culture within the hospital and evaluate the effect on this, it is necessary to periodically evaluate the patient's safety culture and establish regulations on hospital safety culture to comply with this.

• Journal of information and communication convergence engineering
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• v.7 no.2
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• pp.185-192
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• 2009

In wireless mesh networks multi-rate technology environment, a mesh node can dynamically modify the data transmission rate on a particular link, in response to link distance, or more accurately, the perceived SNR ratio between neighbor nodes. In such networks, existing route selection schemes use a link quality metric. Thus, these schemes may easily result in the network being overloaded. In this paper, a new route metric is proposed; it considers both per-hop service delay and link quality at mesh nodes. In addition, the Load-Aware AODV (LA-AODV) protocol using the proposed metric is presented. The performance evaluation is performed by simulation using the OPNET simulator. It is demonstrated that the LA-AODV protocol outperforms the existing routing protocols using other existing route metrics in multi-rate WMN environment.