• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.45 no.4
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• pp.310-317
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• 2017

Recently, many nations are operating and developing Global Navigation Satellite System (GNSS). Also, Satellite Based Augmentation System (SBAS), which uses the geostationary orbit, is operated presently in order to improve the performance of GNSS. The most widely-used SBAS is Wide Area Augmentation System (WAAS) of GPS developed by the United States. SBAS uses various algorithms to offer guaranteed accuracy, availability, continuity and integrity to its users. There is algorithm for guarantees the integrity of the satellite. This algorithm calculates the satellite errors, generates the correction and provides it to the users. The satellite orbit errors are calculated in three-dimensional space in this step. The reference placement is crucial for this three-dimensional calculation of satellite orbit errors. The wider the reference placement becomes, the wider LOS vectors spread, so the more the accuracy improves. For the next step, the regional features of the US and Korea need to be analyzed. Korea has a very narrow geographic features compared to the US. Hence, there may be a problem if the three-dimensional space method of satellite orbit error calculation is used without any modification. This paper suggests a method which uses scalar values to calculate satellite orbit errors instead of using three-dimensional space. Also, this paper proposes the feasibility for this method for a narrow area. The suggested method uses the scalar value, which is a projection of orbit errors on the LOS vector between a reference and a satellite. This method confirms the change in errors according to the baseline distance between Korea and America. The difference in the error change is compared to present the feasibility of the proposed method.

• Journal of Convergence for Information Technology
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• v.10 no.10
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• pp.253-258
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• 2020

This study analyzed, the characteristics of ambulatory care sensitive conditions(ACSCs) in patients visiting emergency departments(EDs) and compared characteristics according to two age groups (adults aged 19-64 years and, elderly people aged ≥65 years). By accessing data from the National Emergency Department Information System(NEDIS) from January 1 to December 31, 2018, we examined the proportions of different ED types and ACSCs, length of stay(LOS) in the ED, LOS hospital, and hospital admission rates. Regarding the types of EDs, we found that the proportion of local emergency medical centers was high(P<0.001). Regarding the rates of different ACSCs, 31.7% of adults were treated for gastroenteritis, a high proportion of the elderly people(48.2%) were diagnosed with and treated for pneumonia(P<0.001). The LOS in the ED was longer in elderly people for all diseases categories, except for congestive heart failure and diabetes(P<0.001). The LOS in the hospital was also significantly longer in elderly people for all ACSCs(P<0.05), and the admission rate was significantly higher in elderly people for all diseases, except for diabetes(P<0.01). Thus, analyzing the ED visits made by patients with ACSCs will need to strengthen the health-care policy to induce treatment centered on outpatient.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.17 no.5
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• pp.77-87
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• 2018

Traffic Density is the most important of the three primary macroscopic traffic stream parameters, because it is most directly related to traffic demand(Traffic Engineering, 2004). It is defined as the number of existing vehicles within a given distance at a certain time. However, due to weather, road conditions, and cost issues, collecting density directly on the field is difficult. This makes studies of density less actively than those of traffic volume or velocity. For these reasons, there is insufficient attempts on divers collecting methods or researches on the accuracy of measured values. In this paper, we used the 'Density Measuring System' based on the synthesise technology of several camera images as a method to measure density. The collected density value by the 'Density Mesuring System' is selected as the true value based on the density define, and this value was compared with the density calculated by the traditional measurement methods. As a result of the comparison, the density value using the fundamental equation method is the closest to the true value as RMSE shows 1.8 to 2.5. In addition, we investigated some issues that can be overlooked easily such as the collecting interval to be considered on collecting density directly by calculating the moment density and the average density. Despite the actual traffic situation of the experiment site is LOS B, it is difficult to judge the real traffic situation because the moment density values per second are observed max 16.0 (veh/km) to min 2.0 (veh/km). However, the average density measured for 15 minutes at 30-second intervals was 8.3-7.9 (veh/km) and it indicates precisely LOS B.

• Cross-Cultural Studies
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• v.46
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• pp.173-197
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• 2017

The present work aims to analyze the concept of space in $Jes{\acute{u}}s$ $Fern{\acute{a}}ndez$ Santos' work Los bravos. Throughout its pages, one can observe the multidimensional possibilities of space in literature. Throughout time, the concept of literary space has developed and it has been modified constantly in order to meet the needs required for the evolution of narratology. In the past, Aristotle stated that space is the place where characters and physical objects happen to exist. This remained almost unchanged until the Renaissance. In the $19^{th}$ century, space stopped being considered just a mere scene where the action takes place as it was given more importance by romantic authors in their works. Realism intensified the spaces as the interior of the house. In fact, the descriptions of space became more important. In this article, I focus on the various meanings of space in the novel Los bravos. First, I analyze the dichotomy between real and ideal spaces, and continue with the cathartic dimension of the fictional space. Then, I present and analyze the opposition between urban and rustic spaces in this novel, and, finally, I show the confrontation between the spaces of men and women. Through this analysis, we can observe that characters have a space where they feel more comfortable and how, occasionally, they leave their "usual space of action" to reach their "ideal place". Women want to stay in their kitchen to chat with each other, while men prefer to leave the house to visit a cafe with their colleagues. The door and the window divide the border of the worlds of men and women. However, that line is not only dividing the structure of the house, but it is also of a psychological house.

• Journal of the Korea Convergence Society
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• v.7 no.4
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• pp.59-66
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• 2016

This study analyzed the relationship between the convergence performance in hospital. This study examined previous research and calculated centralized index using diagnosis related groups. In addition, multiple regression analysis was used based on LOS in order to understand the effect of focused strategy which quality of medical inpatient service. The centralized level was examined by analyzing national inpatient sample data using 'Internal Herfindahl-Hirshman index' This study is significant because it reviewed medical inpatient service quality by measuring hospital centralized level which has been rarely studied before Korea.

• The Journal of Korean Physical Therapy
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• v.25 no.5
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• pp.266-272
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• 2013

Purpose: The purpose of this study was to determine the influence of whole body vibration (WBV) exercise on balance and lower extremity muscle activity according to different intensity of vibration in stroke patients. Methods: Thirty subjects were randomly divided into three groups: experimental group II (n=10), III (n=10), and control group I (n=10). Each subject was exposed to three WBV conditions, as follows: 1. no WBV (group I), 2. 10 Hz (group II), 3. 30 Hz (group III) in semi squat position. The exercise program was conducted for six weeks (five times per week; 16 minutes per day). Subjects were measured on balance (limited of stability: LOS) and lower extremity muscle activity. Results: Significant difference in balance and lower extremity muscle activity was observed in the experimental group (II, III), compared with the control group (I). Results of post-hoc analysis, showed a significant difference in balance (LOS) in on group II and group III compared with group I, but no significant difference in on group II compared with group III, and a significant difference in lower extremity muscle activity in on group II and group III compared with group I, and a significant difference on in group II compared with group III. Conclusion: WBV exercise may be helpful in improvement of balance and lower extremity muscle activity in stroke patients.

• Journal of Satellite, Information and Communications
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• v.10 no.4
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• pp.12-16
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• 2015

Unmanned robot system has become a significant part of network centric warfare. Unnlike the commercial wireless system, however, it is tricky to provide reliable communication in the harsh environment: tactical and military communication. Therefore, it needs to be considered when the base station and mobile has poor communication channel. In this paper, we proposed an efficient operating algorithm for unammned robot system with ensuring communication survivability in the harsh environment. From the simulation, we adopted the SUI channel suitable for domestic mountainous area and open terrain with Rician factor K.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.67 no.11
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• pp.1555-1561
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• 2018

Tracking and detecting targets by the millimeter wave seeker is affected by movement of platform. Stabilization equipments use an inertial sensor to compensate for disturbance of stabilizing gimbal or platform. In the direct line of sight stabilization system, an inertial sensor is mounted on inner gimbal to compensate the disturbance directly, so the performance is excellent and the implementation method is simple. However gimbal design requires somewhat larger volume. Since an inertial sensor is mounted on gimbal base in the indirect line of sight stabilization system, additional space of gimbal is not required for the gimbal design. However, this method does not directly compensate for the disturbance of the line of sight stabilization axis, which can degrade performance. In order to perform the tracking performance, two methods are analyzed for line of sight stabilization performance based on direct and indirect of a 2-axis gimbaled servo system for millimeter wave seeker in this study. The simulation and experimental results validate the performance comparison of two methods.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.13 no.11
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• pp.5410-5426
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• 2019

With the advent of the fifth-generation (5G) era, Massive multiple-input multiple-output (MIMO) relay systems have experienced the rapid development. Recently, the performance analysis models of Massive MIMO relay systems have been proposed, which are mostly based on Rayleigh fading channels. In order to create a more suitable model for 5G Internet of Things scenarios, our study is based on the Rician fading channels, where line-of-sight (LOS) path exists in the channels. In this paper, we assume the channel state information (CSI) is perfect. In this case, we use statistical information to derive the analytical exact closed-form expression for the achievable sum rate of the uplink for the Massive MIMO two-hop relay system over Rician fading channels. Moreover, considering the different communication scenarios, we derive the analytical exact closed-form expression for the achievable sum rates of the uplink for other three scenarios. Finally, based on these expressions, we make simulations and analyze the performance under different transmit powers and Rician-factors, which provides a theoretical basis and reference for further research.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.3 s.106
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• pp.267-271
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• 2006

In this paper, we use the OFDM transmission channel model applied to the MIMO antennas considering spatial propagation property to evaluate and investigate the ergodic capacity of the channel. Specially, we have applied our results to 3GPP TR 25.99 V1.1.0 case 1 LOS off channel description and calculated ergodic capacity with parameters, cluster angle spread and angle of arrival(AOA). Our results show that as the cluster angle spread increase the channel capacity increase until 35 degree, but for more than 35 degree channel capacity does not improved.