• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.17 no.11 s.114
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• pp.1058-1064
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• 2006

In this paper, the channel capacity of a specified wireless indoor multiple-input multiple-output(MIMO) channel is estimated by analyzing spatial characteristics of this channel using the three-dimensional ray tracing method, and a technique for deriving an optimized separation of multi-antenna elements is proposed. At first, the ray paths, the path losses, and the time-delay profile are computed using the three-dimensional ray tracing method in an indoor corridor environment, which has the line of sight(LOS) and non-line of sight(NLOS) regions. The ray tracing method is verified by a comparison between the computation results and the measurements which are obtained with dipole antennas, an amplifier and a network analyzer. Then, an MIMO system is positioned in the indoor channel environment and the ray paths and path losses are computed for four antenna-position combinations and various values of the antenna separation to obtain the channel capacity for the MIMO system. An optimum antenna-separation is derived by averaging the channel capacities of 100 receiver positions with four different antenna combinations.

• Journal of the Korean Association of Geographic Information Studies
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• v.20 no.3
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• pp.67-79
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• 2017

Increasing transportation dependence on the metro system has lead to the convenience of passengers becoming as important as the transportation capacity. In this study, a pedestrian simulator has been developed that can quantitatively assess the pedestrian environment in terms of attributes such as speed and distance. The simulator consists of modules designed for 3D indoor map authoring and algorithmic pedestrian modeling. Module functions for 3D indoor map authoring include 3D spatial modeling, network generation, and evaluation of obtained results. The pedestrian modeling algorithm executes functions such as conducting a path search, allocation of users, and evaluation of level of service (LOS). The primary objective behind developing the said functions is to apply and analyze various scenarios repeatedly, such as before and after the improvement of the pedestrian environment, and to integrate the spatial information database with the dynamic information database. Furthermore, to demonstrate the practical applicability of the proposed simulator in the future, a test-bed was constructed for a currently operational metro station and the quantitative index of the proposed improvement effect was calculated by analyzing the walking speed of pedestrians before and after the improvement of the passage. The possibility of database extension for further analysis has also been discussed in this study.

• Korean Journal of Construction Engineering and Management
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• v.14 no.6
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• pp.3-13
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• 2013

The converted accident rates that included in Pre-Qualification (PQ) are to evaluate the results of accidents which have occurred. Therefore, it is demanded the development of proactive evaluation contents to evaluate the safety management activities and efforts on construction companies. The purpose of this study is to provide basic data for the establishment of proactive evaluation contents at public construction project in Korea through the collected and analyzed the PQ documentation applied by public agencies in Los Angeles, USA. The results indicated that diverse reactive safety evaluations are implemented to examine accidents which occurred in past projects such as occupational health insurance, regulation violation. And also, when the accidents occurred, it is evaluated the proactive safety management actions such as safety education, accident prevention programs, and safety management plans are reflected on the evaluation. Thus, if proactive safety related evaluation contents are established and reflected in PQ examinations together with diverse existing reactive safety evaluations considering converted accident rates, not only the existing function of converted accident rates can be reinforced but also businesses' active safety management activities can be induced and decreases in the construction industry's accident rate can be expected.

• The Journal of the Korea Contents Association
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• v.21 no.4
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• pp.487-497
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• 2021

The purpose of this study is to identify factors affecting length of stay(LOS) and death in tuberculosis(TB) patients by disease type, patient characteristic, admission and disease characteristic, and hospital characteristic from 2008 to 2017. Survey data was using Korean national hospital discharge in-depth survey data produced by Korea Disease Control and Prevention Agency. Study subjects were 10,634 inpatients with TB(A15, A16, A17, A18, A19, U88.0, U88.1, U84.30, U84.31) and analyzed frequency, chi-square test, Fisher's exact test, and logistic regression by using STATA 13.0. As a study result, the type of TB(extrapulmonary TB, multidrug-resistant TB, extensively drug-resistant TB), sex(woman), age(35-49, 50-64, 65-74, 75 years old or older), admission type(outpatient department), CCI(1-2 point, 3 point over), hospital location(metropolitan city) and bed size(300-499, 500-999, over 1000) were significantly influence LOS. Also, the type of TB(extrapulmonary TB, extensively drug-resistant TB), sex(woman), age(50-64, 65-74, 75 years old or older), residence(small town/rural), admission type(outpatient department), CCI(1-2 point, 3 point over), hospital location(provincial) were significantly influence death. In conclusion, the existing tuberculosis management has been patient management with rapid diagnosis and treatment following early detection. But other studies should be carried out for the system that identifies and supports high-risk groups of the long-term length of stay in hospital or high mortality rates as a result of treatment.

• Journal of Industrial Convergence
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• v.22 no.2
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• pp.97-103
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• 2024

The purpose of this study was to examine the impact of balance training on the Inbody and recovery of the balance capability in stroke patient with obesity. The exercise program was to conduct obesity group and normal weight group, 22 subjects were divided equally into experimental(obesity) and controlled group(normal weight), assigned to excercise using the balance training system for 30min a day and 5 days a week. Every pre and post-experimental data of both groups were gathered by Inbody and BSS(Biodex Medical Systems) for 8 weeks. As a result, Comparing the intra-group data measured by Inbody, obesity group showed significant difference in every parameter (p<.05). In the inter-group data, every parameter showed significant difference between both groups (p<.05). Comparing the intra-group data of LOS(Limits Of Stability), obesity group showed significant difference with all parameters, except with 'Backward' and 'Left' (p<.05). In the inter-group data, 'Forward' parameter showed significant difference. Comparing the intra-group data of PS(Postural Stability), obesity group showed significant difference with all parameters (p<.05). The inter-group PS(Postural Stability) results differed significantly only with 'Med/lat'(p=.000). The above results implicate about the following conclusions that the balance training had a big effect on the Inbody and recovery of the balance capability in stroke patient with obesity.

• Bulletin of the Korean Chemical Society
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• v.33 no.8
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• pp.2694-2698
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• 2012

Materials on the scale of nanoscale have widely been used as research topics because of their interesting characteristics and aspects they bring into the field. Out of the many metal oxides, zinc oxide (ZnO) was chosen to be fabricated as nanofibers using the electrospinning method for potential uses of solar cells and sensors. After ZnO nanofibers were obtained, calcination temperature effects on the ZnO nanofibers were studied and reported here. The results of scanning electron microscopy (SEM) revealed that the aggregation of the ZnO nanofibers progressed by calcination. X-ray diffraction (XRD) study showed the hcp ZnO structure was enhanced by calcination at 873 and 1173 K. Transmission electron microscopy (TEM) confirmed the crystallinity of the calcined ZnO nanofibers. X-ray photoelectron spectroscopy (XPS) verified the thermal oxidation of Zn species by calcination in the nanofibers. These techniques have helped us deduce the facts that the diameter of ZnO increases as the calcination temperature was raised; the process of calcination affects the crystallinity of ZnO nanofibers, and the thermal oxidation of Zn species was observed as the calcination temperature was raised.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.197-202
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• 2008

In this paper, a hybrid vibration-impedance approaches is newly proposed to detect the occurrence of damage, the location of damage, and extent of damage in steel plate-girder bridges. The hybrid scheme mainly consists of three sequential phases: 1) to alarm the occurrence of damage, 2) to classify the alarmed damage, and 3) to estimate the classified damage in detail. Damage types of interest include flexural stiffness-loss in girder and bolts-loose in supports. In the first phase, the global occurrence of damage is alarmed by monitoring changes in acceleration features. In the second phase, the alarmed damage is classified into subsystems by recognizing patterns of impedance features. In the final phase, the location and the extent of damage are estimated by using modal strain energy-based damage index method and root mean square deviation method. The feasibility of the proposed system is evaluated on a laboratory-scaled steel plate-girder bridge model for which hybrid vibration-impedance signatures were measured for several damage scenarios.

• Journal of the Korean Institute of Telematics and Electronics C
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• v.35C no.4
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• pp.50-59
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• 1998

This paper describes a 3.3V 8bit CMOS digital to analog converter (DAC) with two state current cell metrix architecture which consists of a 4 MSB and a 4 LSB current matrix stage. The symmetric two stage current cell matrix architecture allow the designed DAC to reduce hot only a complexity of decoding logics, but also a number of wider swing cascode curent mirros. The designed DAC with an active chip area of 0.8 mm$_{2}$ is fabricated by a 0.8 .mu.m CMOS n-well standard digital process. The experimental data shows that the rise/fall time, the settling time, and INL/DNL are6ns, 15ns, and a less than .+-.0.8/.+-.0.75 LB, respectively. The designed DAC is fully operational for the power supply down to 2.0V, such that the DAC is suitable for a low voltage and a low power system application. The power dissipation of the DAC with a single power supply of 3.3V is measured to be 34.5mW.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.88.2-88.2
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• 2013

Exploration of the wave-mode identification and its propagating property in the solar pore is desirable to study the energy transfer in the solar atmosphere. The Fast Imaging Solar Spectrograph (FISS) installed at the New Solar Telescope (NST) is a unique system that can do imaging of H-alpha and Ca II 8542 band simultaneously, which is quite suitable for studying of dynamics of chromosphere. In this study, we inspect a relationship between the cross-sectional area and intensity of the pore at continuum (-0.4 nm) near the Ca II line. We find coherent oscillations of the area and intensity. They shows out-of-phase (~ 180 degree difference) in photosphere, which implies that the oscillation is fast sausage mode. We also investigate a relationship between LOS velocities above the pore obtained from the Ca II and the Ha line cores, and find no significant difference of the phase (~10 degree) between the formation heights of the lines in chromosphere.

• Journal of the Earthquake Engineering Society of Korea
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• v.22 no.4
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• pp.245-251
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• 2018

In this paper, we address some issues in existing seismic hazard closed-form equations and present a novel seismic hazard equation form to overcome these issues. The presented equation form is based on higher-order polynomials, which can well describe the seismic hazard information with relatively high non-linearity. The accuracy of the proposed form is illustrated not only in the seismic hazard data itself but also in estimating the annual probability of failure (APF) of the structural systems. For this purpose, the information on seismic hazard is used in representative areas of the United States (West : Los Angeles, Central : Memphis and Kansas, East : Charleston). Examples regarding the APF estimation are the analyses of existing platform structure and nuclear power plant problems. As a result of the numerical example analyses, it is confirmed that the higher-order-polynomial-based hazard form presented in this paper could predict the APF values of the two example structure systems as well as the given seismic hazard data relatively accurately compared with the existing closed-form hazard equations. Therefore, in the future, it is expected that we can derive a new improved APF function by combining the proposed hazard formula with the existing fragility equation.