• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.4
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• pp.23-28
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• 2023

In a wireless smart utility network communication system, an asynchronous low power MAC is standardized and used according to IEEE 802.15.4e. An asynchronous MAC called RIT (Receiver Initiated Transmission) has a characteristic in which delay time and power consumption are greatly affected by a check-in interval (RIT period). By waking up from sleep every check-in interval and checking whether there is data to be received, power consumption in the receiving end can be drastically reduced, but power consumption in the transmitting end occurs due to an excessive wakeup sequence. If an excessive wake-up sequence is reduced by shortening the check interval, power consumption of the receiving end increases due to too frequent wake-up. In the RIT asynchronous MAC technique, power consumption performance according to traffic load and operation of check-in interval is analyzed and applied to Wi-SUN construction.

• Journal of Positioning, Navigation, and Timing
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• v.5 no.4
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• pp.193-202
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• 2016

The Korea Augmentation Satellite System (KASS), which is under development in Korea as a Satellite Based Augmentation System (SBAS) is expected to broadcast SBAS messages to air space in Korea according to the international standards defined by the International Civil Aviation Organization (ICAO) and the Radio Technical Commission for Aeronautics (RTCA). Around 13 SBAS messages are broadcast in every second to transmit augmentation information which can be applicable to a wide area in common. Each of the messages requires a different update interval and time-out according to the characteristics, purpose, and importance of transmitted information, and users should receive and combine multiple SBAS messages to calculate SBAS augmented information. Thus, a time to take acquiring first SBAS position by users differs depending on broadcasting various SBAS messages with which order and intervals. The present paper analyzes the considerations on message scheduling for broadcasting of KASS augmentation information and proposes a design of KASS message scheduler using the considerations. Compared to existing SBAS systems, which have a wide range of service area, a service area of the KASS is limited to Korea only. Thus, the numbers of ionosphere grid points and satellites to be augmented are expected to be smaller than those of existing SBAS. By reflecting this characteristic to the proposed design, shortening of broadcast interval of KASS message is verified compared to existing SBAS and a measure to increase a speed of acquisition of user navigation solution is proposed utilizing remaining message slots. The simulation result according to the proposed measure showed that the maximum broadcast interval can be reduced by up to 20% compared to that of existing SBAS, and users can acquire KASS position solution faster than existing SBAS.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.38 no.10
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• pp.1171-1177
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• 2014

An electromagnetic shielding doorset must satisfy requirements associated with both mechanical strength/durability and electromagnetic shielding. Among the primary components of the doorset, a finger strip-a leaftype spring normally made of beryllium copper-is a core part to shield electromagnetic waves as well as to endure repetitive dry sliding friction. This study presented a reliability demonstration test method for the doorset system and, by a simple and simultaneous implementation, of the replacement interval of the finger strip. A rigorous evaluation for the qualification of maintenance or replacement interval is included in the reliability demonstration test of any series system that holds critical maintenance sub-units.

• Journal of Biomedical Engineering Research
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• v.28 no.4
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• pp.503-511
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• 2007

Heart rate variability(HRV) is the clinical consequence of various influences of the autonomic nervous system(ANS) on heart beat. HRV can estimate the potential physiologic rhythm from the interval between consecutive beats(RR interval or HRV data), but cardiovascular system governed by ANS is in relation to respiration and autonomic regulation. It is known as RSA representing respiration-related HR rhythmic oscillation. Because the mechanism linking the variability of HR to respiration is complex, it has so far been unknown well. In this paper, we tried to evaluate 5-min RR interval segments under control of respiration in order to find out a proper respiration rate that can estimate the ANS function. 10 healthy volunteers were included to evaluate 5-min HRV data under 4 different respiration-controlled environments; 0.03Hz, 0.1Hz, 0.2Hz, and 0.4Hz respiration. HRV data were analyzed both in the frequency and the time domain, with cross-correlation coefficient(cross-coeff.) for HRV and respiration signal. The results showed maximum cross-coeff. of 0.84 at 0.1 Hz and minimum that of 0.16 at 0.4Hz respiration. Cross-coeff was decreased at a faster rate from 0.1Hz respiration. All mean SDNN, RMSSD, and pNN50 of time domain measures were 108.7ms, 71.85ms, and 28.47%, respectively, and LF, HF, and TP of frequency domain measures were $12,722ms^2,\;658.8ms^2$, and $7,836.64ms^2$ at 0.1Hz respiration, respectively. In conclusion, 0.1Hz respiration was observed to be very meaningful from time domain and frequency domain analysis in relation to respiration and autonomic regulation of the heart.

• Journal of Astronomy and Space Sciences
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• v.26 no.4
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• pp.529-546
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• 2009

Gauss and Laplace methods for initial orbit determination (IOD) are classical orbit determination tools and have been used very efficiently in optical satellite surveillance system. Several studies related to these two methods have been released until now. In this study, we found that the trends of IOD accuracy for different time interval between three pairs of measurement datas show unexpected results. Therefore, we checked the possible cause of these differences. In order to check various orbit types, we used most of satellite data which is able to obtain. To check the characteristics of methodology-only, we used simulated observation data. And we used real observation data for specific satellites to check the characteristics appeared when we applyed these methods to optical satellite surveillance system. As a result, we found that trends of IOD accuracy for time interval could be different because of satellite position observed.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1999.03a
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• pp.237-242
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• 1999

The nature of the interactions between the vestibular and autonomic systems is complex and has not been fully defined. Vestibuloocular reflex induced by sinusoidal rotation and activity of the autonomic nerves in the heart were measured to investigate the interactions between the vestibular system and the autonomic nervous system in healthy adults. Eye movement induced by sinusoidal rotation of the whole body or optokinetic stimulation at 0.04 Hz was analyzed in gain, phase, and symmetry. EKG was measured during vestibular stimulation and analyzed in heart rate variability including mean R-R interval, standard deviation (SD) and coefficient of variance (CV) of R-R interval, and power spectrum of low frequency region (LF) and high frequency region (HF). Gain of eye movement was 0.65${\pm}$0.03 by ratatory stimulation, 0.70${\pm}$0.02 in optokinetic stimulation, 0.08${\pm}$0.02 in visual suppression, and 0.84${\pm}$0.04 in visual enhancement. In R-R interval, resting condition (control) was 0.82${\pm}$0.03 sec, and visual suppression showed significant increase and visual enhancement did significant decrease compared with control (p<0.01).CV was 0.06${\pm}$0.02 in control and visual enhancement increased significantly (p<0.05). In LF/HF control was 1.40${\pm}$0.23, which was not different from rotatory or optokinetic stimulation. But visual suppression decreased LF/HF significantly and visual enhancement increased significantly compared with control (p<0.01). These results suggest that degree of gain corresponds with LF/HF and increased gain in visual enhancement is deeply related to the activity of sympathetic nerves.

• Journal of Biosystems Engineering
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• v.17 no.3
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• pp.213-222
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• 1992

To develop the wireless remote opreating system of walking rice transplanter, this study was carried out for manufacturing the wireless remote control system acting upon the transplanter. The first report of this study contained about the construction and operating method of a developed remote control system for 2-row walking type transplanter. It is the second report about the field test for an experimental transplanter being attached a wireless control system and for a conventional transplanter. The test was executed to investigate the characteristics of velocity, rectilinearity, turning time, interval of roots and of rows, and field capacity in accordance with various engine speeds for an experimental transplanter. The measurements of this test were compared with those of the conventional transplanter. The obtained results were as follows : 1. The operating velocity of the experimental transplanter was faster than the conventional one when the high speed range of the engine but the variances were very large. 2. The rectilinearity, interval of raws and of roots, and the turning time of the experimental transplanter was inferior to the conventional one at some speed ranges of the engine. 3. Field capacity of the experimental transplanter was superior to the conventional one at high speed of the engine. 4. There were some disadvantages for the experimental transplanter to operate, because it was constructed without any aid devices, such as float and hydraulic system for instance. But if the remote control system of this study equip at the modern walking transplanter, it will be improved and utilized without defects which was revealed from this test.

• Radiation Oncology Journal
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• v.30 no.4
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• pp.182-188
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• 2012

Purpose: For recurrent esophageal cancer after primary definitive radiotherapy, no general treatment guidelines are available. We evaluated the toxicities and clinical outcomes of re-irradiation (re-RT) for recurrent esophageal cancer. Materials and Methods: We analyzed 10 patients with recurrent esophageal cancer treated with re-RT after primary definitive radiotherapy. The median time interval between primary radiotherapy and re-RT was 15.6 months (range, 4.8 to 36.4 months). The total dose of primary radiotherapy was a median of 50.4 Gy (range, 50.4 to 63.0 Gy). The total dose of re-RT was a median of 46.5 Gy (range, 44.0 to 50.4 Gy). Results: The median follow-up period was 4.9 months (range, 2.6 to 11.4 months). The tumor response at 3 months after the end of re-RT was complete response (n = 2), partial response (n = 1), stable disease (n = 2), and progressive disease (n = 5). Grade 5 tracheoesophageal fistula developed in three patients. The time interval between primary radiotherapy and re-RT was less than 12 months in two of these three patients. Late toxicities included grade 1 dysphagia (n = 1). Conclusion: Re-RT of recurrent esophageal cancer after primary radiotherapy can cause severe toxicity.

• Journal of the Korean Geosynthetics Society
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• v.22 no.4
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• pp.73-82
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• 2023

In this study, the optimal method for injection of neutralizer to restraint the leakage of acid drainage in embankment structure composed of pyrite rocks is proposed. Finite Element Analysis was performed to examine the seepage effect caused by injection of neutralizer into the embankment structure. The diameter of the neutralizer injection hole was selected as 50cm, the interval space of injection ranged from 1m to 4m and the injecting pressure ranged from 100kPa to 220 kPa were applied for the numerical analysis. According to the analysis results, the saturation time of the whole embankment structure was shown to be fast at a relatively low injecting pressure in the case of injecting interval space of 1.0m and injecting pressure of 130kPa and in the case of injecting interval space of 2.0m and injecting pressure of 160kPa. When the interval space of injection for saturation of whole embankment structure is selected as 3m, various injection pressures can be applied from 130kPa to 190kPa, and the saturation time of whole embankment is similar regardless of the injection pressure. Therefore, the optimal method for injection of neutralizer considering economic efficiency was selected as injecting interval space of 3.0m and injection pressure of 130kPa.

• Proceedings of the Korea Association of Information Systems Conference
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• 1996.11a
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• pp.205-210
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• 1996

The bootstrap procedure is suggested as a useful method for point and interval estimation of system availability. Its validity and robustness has been shown in special, but representative case, by various sampling experiments. Alternative to the bootstrap suggest themselves e.g. a variation of the 'F'technique, but remain to be evaluated, as do variations on the bootstrap itself.