• Journal of Broadcast Engineering
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• v.25 no.5
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• pp.734-741
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• 2020

This article proposes a new pedestrian avoidance algorithm for social robots that coexist and communicate with humans and do not induce stress caused by invasion of psychological safety distance(Social Distance). To redefine the pedestrian model, pedestrians are clustered according to the pedestrian's gait characteristics(straightness, speed) and a social distance is defined for each pedestrian cluster. After modeling pedestrians(obstacles) with the social distances, integrated navigation algorithm is completed by applying the newly defined pedestrian model to commercial obstacle avoidance and path planning algorithms. To show the effectiveness of the proposed algorithm, two commercial obstacle avoidance & path planning algorithms(the Dynamic Window Approach (DWA) algorithm and the Timed Elastic Bands (TEB) algorithm) are used. Four cases were experimented in applying and non-applying the new pedestrian model, respectively. Simulation results show that the proposed algorithm can significantly reduce the stress index of pedestrians without loss of traveling time.

• Journal of Korean Academy of Nursing
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• v.29 no.1
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• pp.161-173
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• 1999

The purpose of this study was to develope and test the structural model for quality of life in women having hysterectomies. A hypothetical model was constructed on the basis of previous studies and a review of literature. The conceptual framework was built around eight constructs. Exogenous variables included in this model were marital intimacy, importance of uterus, professional support, positive coping behavior and pre-operative symptoms. Endogenous variables were spouse's support, sense of loss and quality of life. Empirical data for testing the hypothetical model was collected using a self-report questionnare from 203 women having hysterectomies at the outpatient clinics of four general hospitals and a mail survey in Pusan City. The Data was collected from December, 1997 to January, 1998. Reliability of the eight instruments was tested with Cronbach's alpha which ranged from 0.639-0.915. For the data analysis, SPSS 7.5 WIN Program and LISREL 8.12 WIN Program were used for descriptive statistics and covariance structural analysis. The results of covariance structure analysis were as follows : 1. Hypothetical model showed a good fit with the empirical data. ［$\chi$$^2$＝6.93(df＝5, P＝.23), GFI＝.99, AGFI＝.94, RMSR＝.019, NNFI＝.97, NFI＝.98, CN＝440, standardized residuals(-2.14-2.10)］ 2. For the parsimony of model, a modified model was constructed by deleting 3 paths and adding 1 path according to the criteria of statistical significance and meaning. 3. The modified model also showed a good fit with the data. ［$\chi$$^2$＝5.26(df＝7, P＝.63), GFI＝.99, AGFI＝.97, RMSR＝.014, NNFI＝1.02, NFI＝.99, CN＝710, standardized residuals(-1.46-1.70)］ Results of the testing of the hypothesis were as follows : 1. Marital intimacy(${\gamma}$11＝.78, t＝14.37) and professional support(${\gamma}$13＝.12, t＝2.12) had a significant direct effect on the spouse's support. 2. Pre-operative symptoms(${\gamma}$25＝.32, t＝3.12), importance of uterus(${\gamma}$22＝.20, t＝2.61) and spouse's support($\beta$2l＝-.19, t＝-2.43) had a significant direct effect on the sense of loss. 3. Sense of loss($\beta$32＝-.66, t＝-9.83) had a direct effect on the quality of life. Marital intimacy had a direct(${\gamma}$31＝.19, t＝3.33), indirect(${\gamma}$31＝.14, t＝2.52) and total effect(${\gamma}$31＝.25, t＝4.41) on the quality of life. Professional support had a direct effect(${\gamma}$33＝.11, t＝2.07) and total effect(${\gamma}$33＝.13, t＝2.31) on the quality of life. The direct effect of pre-operative symptoms(${\gamma}$35＝-.36, t＝4.02) and positive coping behavior(${\gamma}$34＝.15, t＝2.06) had the insignificant effect on the quality of life while, due to the idirect effect these variables had overall significant effect on the quality of life. The results of this study showed that the sense of loss had the most significant direct effect on the quality of life. Marital intimacy, pre -operative symptoms and spouse's support had a significant direct effect on this sense of loss. These four variables, the sense of loss, marital intimacy, pre-operative symptoms and spouse's support, were identified as relatively important variables. The results of this study suggested that there is needed to determine if nursing intervention would alleviate this sense of loss and promote a greater quality of life in women who have had hysterectomies.

• Journal of the Korean Society of Clothing and Textiles
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• v.37 no.6
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• pp.772-785
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• 2013

This study investigated the effects of fashion consumer's browsing motives and risk perception on impulse buying and purchase intention in social commerce. The online survey results of 317 customers who experienced using fashion products via social commerce were used for the final analysis. Exploratory factor analysis, reliability analysis, and frequency analysis were conducted using SPSS 18.0, and confirmatory factor analysis and path analysis were performed with AMOS 18.0. Three browsing motives (hedonic motive, rational motive, and informational motive) and three risk perceptions (products-related risk, customer service risk, and opportunity loss risk) were identified. The results from the structure equation model were as follows. 1) It was deducted that the browsing motive did not have a significant effect on risk perception due to the rejection of most of the hypotheses in regards to the browsing motive influence on risk perception. 2) Product-related risk and customer service risk had a significantly negative effect on purchase intention. Opportunity loss risk had significantly positive effect on impulse buying and purchase intention. 3) Hedonic browsing motive had a significant effect on impulse buying, and rational motive had a significant effect on impulse buying and purchase intention. The informational browsing motive had a significant effect only on purchase intention.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.8 no.3
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• pp.310-317
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• 1997

Due to the congestion of the radio spectrum, frequency bands are shared among the communication systems. Therefore for the satisfactory operation we have to predict with reasonable accuracy the levels of interference that might exist among them. Inter- ference among the communication systems depends on many factors such as climate, radio frequency, time percentage of interest, distance and path topography. Interference due to rain scattering is the most important factorin Ghz frequencies. ITU-R offers the model related to interference due to rain scattering. In this paper the transmission loss due to rain scattering is predicted and compared with the measured results.

• Journal of Advanced Navigation Technology
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• v.5 no.1
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• pp.62-73
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• 2001

In this paper, performance of DSRC systems is analyzed with considering the real roads and height of vehicles. The channels are modeled as 2-Ray and 4-Ray with a direct wave and reflected waves by a road and buildings in a physical layer because DSRC keeps LOS propagation characteristics, and the pass loss for each model is calculated respectively. Rician factor is obtained through the calculated path loss on two models for DSRC, and the performance of the systems is analyzed in AWGN and Rician fading channels, Impulsive noise and Rician fading channels respectively. As a result, in Rician fading channels with impulsive noise(A=0.2, ${\Gamma}^{\prime}=0.22$), BER is below $10^{-6}$ when the distance is farther than 80[m] and 40[m] in 2-Ray model and 4-Ray model respectively. For performance improvement, BCH coding scheme and MRC diversity scheme are adopted.

• Progress in Superconductivity and Cryogenics
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• v.16 no.2
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• pp.42-46
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• 2014

In this study we investigated ac transport current losses in the face to face stack for the anti-parallel current flow, and compared the electromagnetic properties with those of the single SC tape as well as those of the same stack for the parallel current path. The gap between the SC tapes in the stack varied in order to verify the electromagnetic influence of the neighbors when current flows in opposite direction, and the model was implemented in the finite element method program by the commercial software, COMSOL Multiphysics 4.2a. Conclusively speaking, the loss was remarkably decreased for the anti-parallel current case, which is attributed the magnetic flux compensation between the SC layers due to the opposite direction of the current flows. As the gap between SC tapes was increased, the loss mitigation became less effective. Besides, the current density distribution is very flat cross the sample width for the narrower gap case, which is believed to be benefit for the power electric system. These results are all in good agreement with those predicted theoretically for an infinite bifilar stack.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.3
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• pp.395-406
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• 2018

The XP-SWMM model, widely used for inundation analysis of urban watersheds, underestimated the inundation area (range) because the manhole was regarded as a node and the influence of the local loss occurring in the surcharged manhole can not be considered. Therefore, it is necessary to analyze the applicability of the head loss coefficients considering the local loss in the surcharged manholes in inundation analysis using XP-SWMM. The Dorim 1 drainage section of the Dorim-river watershed, where frequent domestic flood damage occurred, was selected as the study watershed. The head loss coefficients of the surcharged manholes estimated from the previous experimental studies were applied to the inundation analysis, and the changes of the inundation area with and without the application of the head loss coefficients with manhole types were compared and analyzed. As a result of inundation simulation with the application of head loss coefficients, the matching rates were increased by 17% in comparison with the without application of them. In addition, the simulated inundation area applied only the head loss coefficients of straight path manholes and applied up to the head loss coefficients of combining manholes ($90^{\circ}$ bend, 3-way, and 4-way) were similar. Therefore, in order to accurately simulate the storm drain system in urban areas, it could be to carry out two-dimensional inundation analysis considering the head loss coefficients at the surcharged manholes. It was expected that the study results will be utilized as basic data for establishing the identification of the inundation risk area.

• KSII Transactions on Internet and Information Systems (TIIS)
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• v.8 no.8
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• pp.2663-2674
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• 2014

For cognitive radio sensor networks (CRSNs) that use underlay-based spectrum access, the location of the primary user (PU) plays an important role in the power control of the secondary users (SUs), because the SUs must keep the minimum interference level required by the PU. Received signal strength (RSS)-based localization schemes provide low-cost implementation and low complexity, thus it is suitable for the PU localization in CRSNs. However, the RSS-based localization schemes have a high localization error because they use an inexact path loss exponent (PLE). Thus, applying a RSS-based localization scheme into the PU localization would cause a high interference to the PU. In order to reduce the localization error and improve the channel reuse rate, we propose a RSS-based PU localization scheme that uses distance calibration for CRSNs using underlay model-based spectrum access. Through the simulation results, it is shown that the proposed scheme can provide less localization error as well as more spectrum utilization than the RSS-based PU localization using the mean and the maximum likelihood calibration.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.14 no.4
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• pp.80-85
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• 2015

The era of intelligent transportation system(ITS) has been arrived by applying information and communication technology(ICT) to the traffic. One of these technological advances is a wireless communication technology for a high speed vehicle to be connected to an infrastructure(V2I). A variety of road traffic safety services and operator comfort services are being developed by means of WAVE(Wireless Access in a Vehicular Environment) based on IEEE802.11p Standard. In this paper, the link budget is analyzed to provide a reliable quality of these ITS services. Log-distance model and two-ray model is employed for the wave propagation path loss model which is adequate for a highway environment. Reliable cell coverage is suggested for ITS services from the link budget.

• Nuclear Engineering and Technology
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• v.38 no.4
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• pp.343-352
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• 2006

Convenient analytical tools for evaluation of the aperiodic and the fluctuating instabilities of the passive residual heat removal system (PRHRS) of an integral reactor are developed and results are discussed from the viewpoint of the system design. First, a static model for the aperiodic instability using the system hydraulic loss relation and the downcomer feedwater heating equations is developed. The calculated hydraulic relation between the pressure drop and the feedwater flow rate shows that several static states can exist with various numbers of water-mode feedwater module pipes. It is shown that the most probable state can exist by basic physical reasoning, that there is no flow rate through the steam-mode feedwater module pipes. Second, a dynamic model for the fluctuating instability due to steam generation retardation in the steam generator and the dynamic interaction of two compressible volumes, that is, the steam volume of the main steam pipe lines and the gas volume of the compensating tank is formulated and the D-decomposition method is applied after linearization of the governing equations. The results show that the PRHRS becomes stabilized with a smaller volume compensating tank, a larger volume steam space and higher hydraulic resistance of the path $a_{ct}$. Increasing the operating steam pressure has a stabilizing effect. The analytical model and the results obtained from this study will be utilized for PRHRS performance improvement.