• The Korean Journal of Emergency Medical Services
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• v.1 no.1
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• pp.42-53
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• 1997

To offer basic data about the influential factors on patient's Satisfaction level for emergency medical services the authors were performed this study in 60 patients visited to emergency room of third stage general hospital in Taejeon city. Data were collected through interview with patients by using a 15 items' questionaire according to care subscale, teaching subscale of Likert's five stage quantitative scale and the tools developed by Barbara Davis. The data were analyzed by using the SPSS/PC computerized program for mean, standard deviation, percentage, ANOVA, t-test, and pearson correlation. The results are as followings ; 1. Satisfaction of emergency medical service were showed in care area, but not showed in teaching and total area 2. Satisfaction of sociodemographic characteristics were a statistically significant difference only marriage, that were the higher in marriaged than single(P<.0.05). 3. In the emergency situation characteristics the satisfaction accordings to the visit cause were lower in accident than disease group, the reason of hospital selection were in order trust, introduction group, distance, traffic, kinds, and score of satisfaction were showed each of 43.47, 51.27(P<.001), the transportation vehicle was the 119, hospital ambulance group. but were not a satistically significant difference. 4. The negative correlation was observed between satisfaction and the length of stay at ER and the longer length of stay at ER was showed the lower satisfaction. But the positive correlation was observed between satisfacton and the arrival time, patients who arrived ER from 6:00P.M. to midnight were more satisfied than patients who arrived other time. 5. The length of stay at ER was significantly different according to the reason of hospital selection, the reason of ER selection, the visitant cause and hopital decisioner. Especially the length of stay was much longer in accident group and unconscious group.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.20 no.3
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• pp.74-85
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• 2021

Global Navigation Satellite System (GNSS) receivers are intrinsically vulnerable to radio frequency jamming signals due to the fundamental property of radio navigation systems. A GNSS jamming monitoring system that is capable of jamming detection, classification and localization is essential for infrastructure for autonomous driving systems. For these 3 functionalities, a GNSS jamming monitoring network consisting of a multiple of low-cost GNSS receivers distributed in a certain area is needed, and the precise time synchronizaion between multiple independent GNSS receivers in the network is an essential element. This paper presents a precise time synchronization method based on the direct use of Time Difference of Arrival (TDOA) technique in signal domain. A block interpolation method is additionally incorporated into the method in order to maintain the precision of time synchronization even with the relatively low sampling rate of the received signals for computational efficiency. The feasibility of the proposed approach is verified in the numerical simualtions.

• Journal of the Institute of Electronics and Information Engineers
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• v.50 no.6
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• pp.62-71
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• 2013

The passive emitter location method using TDOA and FDOA measurements has higher accuracy comparing to the single TDOA or FDOA based method. Moreover, it is able to estimate the velocity vector of a moving platform. Recently, several non-iterative methods were suggested using the nuisance parameter but the common reference sensor is needed for each pair of sensors. They show also relatively low performance in the case of a long range between the sensor groups and the emitter. To solve this, we derive the estimation method of the position and velocity of a moving platform based on the Gauss-Newton method. In addition, to analyze the estimation performance of the position and velocity, respectively, we decompose the CRLB matrix into each subspace. Simulation results show the estimation performance of the derived method and the CEP planes according to the given geometry of the sensors.

• Journal of Korean Academy of Fundamentals of Nursing
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• v.22 no.2
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• pp.149-157
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• 2015

Purpose: The objectives of this study were to assess the influence of family presence in the PACU (Post Anesthesia Care Unit) on anxiety, emergency delirium, pain and length of stay in the recovery room for elderly patients undergoing surgery for which general anesthesia has been used. Methods: The study was a nonequivalent control group pre-post test design. Eighty elderly patients over 65 years who underwent surgery under general anesthesia were recruited. Forty were assigned to the experiment group, patients together with a family member and 40 to the control group, with no family member present. Patients' anxiety, emergency delirium, pain and length of time in the recovery room were evaluated at 10 minute and 30 minute after arrival in the PACU. Results: Patients with family members in the PACU showed significantly decreased levels of anxiety at 10 and 30 minutes and significantly lower levels of emergency delirium and pain at 30 minutes. However there was no difference between the 2 groups for length of time in the recovery room. Conclusion: The results of this study indicate that being with family members in the PACU after surgery under general anesthesia is effective for reducing elderly patients' anxiety, delirium and pain during time in the recovery room.

• Journal of the Institute of Electronics and Information Engineers
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• v.53 no.7
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• pp.85-91
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• 2016

Typically, radar systems change the pulse repetition interval of their modulated signal in order to avoid detection. On the other hand the radar-signal detection system tries to detect the modulation pattern. The histogram or auto-correlation methods are usually used to detect the PRI pattern of the radar signal. However these methods tend to lost the sequence information of the PRI pulses. This paper proposes a PRI-sequence detection algorithm based on the finite-state machine that could detect not only the PRI pattern but also their sequence.

• Journal of the Korean Institute of Telematics and Electronics S
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• v.34S no.5
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• pp.1-14
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• 1997

We consider transmission beamforming techniques for frequency-division-duplex (FDD) wireless communication systems using adaptive arrays to improve the signal quality of the array transmission link. We develop a simple effective transmission beamforming technique based on an approximated frequency tranlsation (AFT) to derive the tranmsiion beamforming weights from the uplink channel vector. This technique exploits the invariance of the short-time averaged fast fading statistics to small frequency translations. A simple approximate relationship that relates the transmission channel vector to the reception channel vector is derived. We have developed its practical alternative in which the frequency translation of the channel vector is performed at the principal angle of arrival (AOA) of the u;link synthestic angular spectrum instead of the mean AOA. To analyze the performance of the proposed methods, we consider the power loss incurred by applying the estimated channel vector instead of the true downlink channel vector. The performance is analyzed as a function of the mean AOA, the angular spread, the number of elements, frequncy difference between the uplink and the downlink, and the angle distribution. Their performance is also compared with that of the direct weight reuse method and the AOA based methods.

• Journal of Electrical Engineering and Technology
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• v.8 no.6
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• pp.1468-1473
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• 2013

This paper dealt with the propagation characteristics of acoustic signals produced by partial discharges and the positioning of PD origin in insulation oil to develop insulation diagnostic techniques of oil-immerged transformers. Electrode systems such as needle to plane, plane to plane, and particle electrodes were fabricated to simulate some defects of power transformers. In addition, the frequency spectrum and propagation characteristics of acoustic signals with partial discharge (PD) in insulation oil were analyzed. Although there were differences based on the type of defect, the frequency spectra of the acoustic signals measured by wide and narrow band acoustic emission (AE) sensors were distributed in the range of 50 kHz-400 kHz. Therefore, a narrowband AE sensor is suitable for the diagnosis of oil-immersed power transformers. We could find the position of the PD source with an error margin of 10% in the experiments by calculating the position of the PD occurrence using the time difference of arrival measured by five AE sensors.

• Journal of KIISE:Computer Systems and Theory
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• v.36 no.2
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• pp.94-101
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• 2009

We introduce a user authentication system using distance estimation and a simple challenge response protocol based on a pre-established key. Using the time difference of arrival between an RF signal and an ultrasonic signal, an authenticator verifies if a user's authentication token is within its threshold distance, and it also verifies if the token's response to its random challenge is valid. We implement our authentication system and we analyze the success rates for authentication according to the variations in the distances and facing angles between the authenticator and the token. Our experimental results show that the token is authenticated with very high probability in reasonable settings.

• Journal of Institute of Control, Robotics and Systems
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• v.18 no.4
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• pp.375-383
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• 2012

Together with the GPS-based approach, geolocation through mobile communication networks is a key technology for location-based service. Since the Mobile WiMAX system is considered as a candidate for fourth-generation mobile systems, it is important to investigate its location capability. The geolocation of Mobile WiMAX can be realized when the preamble symbols in the down-link channel are appropriately used for a TDOA (Time-Difference-of-Arrival) approach. However, the cellular structure of Mobile WiMAX inevitably generates co-channel interference, and it is difficult for the mobile terminal to acquire distance measurements from multiple base stations. Therefore, for geolocation via multilateration using the Mobile WiMAX network, it is very important to increase hearability. This paper proposes a geolocation method for Mobile WiMAX which employs interference cancellation and preamble signal overlapping for the enhancement of hearability. A novel interference cancellation strategy for complex-valued Mobile WiMAX signals is presented which has an iterative structure. Simulation results show that the proposed geolocation method provides the user's position with an accuracy of less than 20 m through the Mobile WiMAX cellular network if there is no multi-path or NLOS (None-Line-of-Sight).

• ETRI Journal
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• v.39 no.2
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• pp.264-274
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• 2017

Recently, mobile positioning enhancement has attracted much attention in the 3rd generation partnership project long-term evolution system. In particular, for urban canyon environments, the need for three-dimensional (3D) positioning has increased to enable the altitude of users to be measured. For several decades, several time difference of arrival (TDOA-) based 3D positioning methods have been studied; however, they are only available when at least four evolved Node Bs (eNBs) exist nearby or when all eNBs have the same height. Therefore, in this paper, we propose a new 3D positioning method that estimates the 3D coordinates of a user using three types of two-dimensional (2D) TDOAs. However, the give inaccurate results owing to the undefined axis of the 2D coordinate plane. Therefore, we propose a novel derivation of the hyperbola equation, which includes the undefined axis coordinate in the 2D hyperbola equation. Then, we propose an interaction algorithm that mutually supplies the undefined axis coordinate of users among 2D TDOAs. By performing extensive simulations, we verify that the proposed method is the only solution applicable by using three eNBs with different heights.