• Journal of the Computational Structural Engineering Institute of Korea
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• v.24 no.5
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• pp.553-567
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• 2011

During the last three years, the possibility of the time reversal Lamb waves has been paid attention to for structural health monitoring of a plate. This study proposes a numerical scheme which can simulate the spatial focusing of time reversal Lamb waves on a rectangular plate. In this scheme, a time reversal process is formulated in the frequency domain using active virtual sensors being equivalent to the mirror effects of an actual sensor due to wave reflection on the plate boundary. Forward and backward Lamb wave propagations are represented by scalar functions for simulating the spatial focusing of time reversal Lamb waves. The validity of the proposed scheme is demonstrated through the comparison to the results of finite element analysis in which the spatial focusing of time reversal Lamb waves is realized by wafer-type piezoelectric(PZT) transducers collocated on a rectangular plate.

• Wind and Structures
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• v.23 no.4
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• pp.313-350
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• 2016

Taipei 101 Tower, which has 101 stories with height of 508 m, is located in Taipei where typhoons and earthquakes commonly occur. It is currently the second tallest building in the world. Therefore, the dynamic performance of the super-tall building under strong wind actions requires particular attentions. In this study, Large Eddy Simulation (LES) integrated with a new inflow turbulence generator and a new sub-grid scale (SGS) model was conducted to simulate the wind loads on the super-tall building. Three-dimensional finite element model of Taipei 101 Tower was established and used to evaluate the wind-induced responses of the high-rise structure based on the simulated wind forces. The numerical results were found to be consistent with those measured from a vibration monitoring system installed in the building. Furthermore, the equivalent static wind loads on the building, which were computed by the time-domain and frequency-domain analysis, respectively, were in satisfactory agreement with available wind tunnel testing results. It has been demonstrated through the validation studies that the numerical framework presented in this paper, including the recommended SGS model, the inflow turbulence generation technique and associated numerical treatments, is a useful tool for evaluation of the wind loads and wind-induced responses of tall buildings.

• Proceedings of the Korean Geotechical Society Conference
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• 2007.09a
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• pp.266-292
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• 2007

Round Robin Test (RRT) on ground response analyses was conducted for three sites in Korea based on several site investigation data, which include borehole logs with the N values from standard penetration test (SPT) for all three sites and additionally cone tip resistance profiles for two sites. Three input earthquake motions together with the site investigation data were provided for the RRT. A total of 12 teams participating in this RRT presented the results of ground response analyses using equivalent-linear and/or nonlinear method. Each team determined input geotechnical properties by using empirical relationships and literatures based on own judgment, with the exception of the input motions. Herein, the characteristics of input motions were compared in terms of the frequency and period, and the selection of the depth to bedrock, on which the motions is impinged, was discussed considering geologic conditions in Korea. Furthermore, a variety of geotechnical properties such as shear wave velocity profiles and soil nonlinear curves were investigated with the input properties used in this RRT.

• The Journal of Korean Institute of Electromagnetic Engineering and Science
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• v.21 no.2
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• pp.143-151
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• 2010

In this paper, a novel rectangular patch antenna is proposed to have Zeroth Order Resonance(ZOR) generated based on the Metamaterial Complosite Right- and Left-Handed(CRLH) structure. Making the in-phase electric field over the entire antenna other than a half-wavelength as the fundamental resonance mode of a standard microstrip patch or its positive multiple, the metallic patch is suggested to be capacitively coupled with only one surrounding rectangular ring, different from the previous 1D ZOR antennas commonly having several metal cells in line. The performance of the proposed antenna is simulated by a 3D field solver that inputs the sizes of the physical structure corresponding to the equivalent circuit designed to have ZOR at 2.4 GHz. Consequently, the resonance frequency, the gain and the antenna efficiency are observed 2.4 GHz, 5 dB and 98%, respectively. Besides, the important property of the proposed antenna is addressed as the combination of the low profile as an advantage of microstrip patch antennas, and the omni-directional field pattern typical of monopole antennas.

• Journal of Environmental Science International
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• v.25 no.6
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• pp.839-851
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• 2016

The effect of weather on disease was investigated based on results reported in academic papers. Weather-sensitive disease was selected by analyzing the frequency distributions of diseases and correlations between diseases and meteorological factors (e.g., temperature, humidity, pressure, and wind speed). Correlations between disease and meteorological factors were most frequently reported for myocardial infarction (MI) (28%) followed by chronic ischemic heart disease (CHR) (12%), stroke (STR) (10%), and angina pectoris (ANG) (5%). These four diseases had significant correlations with temperature (meaningful correlation for MI and negative correlations for CHR, STR, and ANG). Selecting MI, as a representative weather-sensitive disease, and summarizing the quantitative correlations with meteorological factors revealed that, daily hospital admissions for MI increased approximately 1.7%-2.2% with each $1^{\circ}C$ decrease in physiologically equivalent temperature. On the days when MI occurred in three or more patients larger daily temperature ranges ($2.3^{\circ}C$ increase) were reported compared with the days when MI occurred in fewer than three patients. In addition, variations in pressure (10 mbar, 1016 mbar standard) and relative humidity (10%) contributed to an 11%-12% increase in deaths from MI and an approximately 10% increase in the incidence of MI, respectively.

• The Journal of Korean Academic Society of Nursing Education
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• v.6 no.1
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• pp.103-114
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• 2000

The purpose of this study was to determine the effect of nursing education in diabetes patient, and to define the strategy to promote their sick-roll behavior, self efficacy. The quasi-experimental design was designed non-equivalent control group, non-synchronized design. The study had been done by investigating the experimental group and control group through the questionnaire on 58 patients who had been hospitalized and visiting out-patient department in K hospital in Pusan from June 1, 1998 to September 30, 1998. Individual diabetes education was carried out experimental group for the average 45 minutes. Self-efficacy was measured by Diabetes Management Self-efficacy Instrument developed by Park(1984). Data was collected before and after the experimentation. Collected data was analyzed by means of frequency, percentage, chi-square test, mean, standard deviation, and t-test with SPSS/PC program. The results were summarized as follows : 1. 'The experimental group which received the individual diabetes education should be higher in self-efficacy than control group' was not supported. 2. 'The experimental group which received the individual diabetes education should be higher in sick-roll behavior than control group' was not supported(P=.043). In conclusion, the patient who received individual diabetes education showed the increase in degree of sick - roll behavior of diabetes patients. So individual diabetes education had been judged the nursing intervention to improve sick-roll behavior of diabetes patients. But there was no effect about self-efficacy so to have the program which can improve self-efficacy is needed.

• Journal of Korean Biological Nursing Science
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• v.3 no.2
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• pp.69-90
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• 2001

The purpose of this study was to determine the effect of dance sports on physiological variables, depression and quality of life in the elderly. The study was performed on a non-equivalent control group pretest-posttest design for 47 elderly, who were conveniently assigned to experimental group and control group. The experimental group were selected from D-welfare facility and the control group were selected from G-elderly church club in G-city. The data were collected from April 2, 2001 to June 30, 2001, and analyzed by frequency, $x^2$-test, t-test and paired t-test using SAS/PC program. The results of this study were summarized as follows; 1. The first hypothesis, "the experimental group would have improved physiological variables than the control group.". 1-1. The hypothesis, "the experimental group would have lower blood pressure than the control group" was rejected. 1-2. The hypothesis, "the experimental group would have lower heart rate than the control group" was supported(t=-2.031, p=0.048). 1-3. The hypothesis, "the experimental group would have higher peripheral vessel $O_2$ Saturation than the control group" was rejected. 2. The second hypothesis, "the experimental group would have lower depression score than the control group" was supported(t=2.832, p=0.006). 3. The third hypothesis, "the experimental group would have higher quality of life score than the control group" was supported(t=2.604, p=0.012). After 12 weeks of dance sports program, it was shown that the program was effective to improve the physiological varibles, reduce depression and improve quality of life.

• The Proceeding of the Korean Institute of Electromagnetic Engineering and Science
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• v.2 no.4
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• pp.17-25
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• 1991

Slotted coaxial cables are used for a wide variety of radio communications and control applications within buildings, subways, tunnels and outdoors. They function as continuous antennas to solve RF coverage problems in difficult or confined areas. In this paper the electric and magnetic field distributions inside and outside of axially slotted coaxial cables are analyzed numerically. This paper gets the fields from the equivalent potentials which are obtained by grid relaxation method. The slot electric field configurations are consistent with Essam E. Hassan's results. The field distributions in the slotted coaxial cables show that the TEM mode doesn't propagate any longer in them. But the fields don't variate with the frequencies that are under the first higher order mode cutoff frequency of shielded coaxial cable of the same dimension The fields inside of the tunnel ($3\times4$) including the slotted coaxial cable axially are similar to those of $TE_{10}$ mode at 38.75 MHz. This method offers the basis for theoretical analysis of coaxial cables with nonuniform slots as well as coaxial cables in tunnels and buildings.

• Journal of Korean Academy of Nursing
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• v.41 no.2
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• pp.245-255
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• 2011

Purpose: This study was conducted to examine the effects of simulation-based education regarding care in a cardio-pulmonary emergency care as related to knowledge, clinical performance ability, and problem solving process in new nurses. Methods: An equivalent control group pre-post test experimental design was used. Fifty new nurses were recruited, 26 nurses for the experimental group and 24 nurses for the control group. The simulation-based cardio-pulmonary emergency care education included lecture, skill training, team-based practice, and debriefing, and it was implemented with the experimental group for a week in May, 2009. Data were analyzed using frequency, ratio, chi-square, Fisher's exact probability and t-test with the SPSS program. Results: The experimental group who had the simulation-based education showed significantly higher know-ledge (t=5.76, p<.001) and clinical performance ability (t=5.86, p<.001) for cardio-pulmonary emergency care compared with the control group who had traditional education but problem solving process was not included (t=1.11, p=.138). Conclusion: The results indicate that a simulation-based education is an effective teaching method to improve knowledge and clinical performance ability in new nurses learning cardio-pulmonary emergency care. Further study is needed to identify the effect of a simulation-based team discussion on cognitive outcome of clinical nurses such as problem solving skills.

• The Transactions of the Korean Institute of Power Electronics
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• v.14 no.6
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• pp.457-465
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• 2009

Lithium batteries are widely used in mobile electronic devices due to their higher voltage and energy density, lighter weight and longer life cycle compared to other secondary batteries. In particular, high demand for lithium batteries is expected for electric cars. In case of lithium batteries used in electric cars, driving distance must be calculated accurately and discharging should not be done below the level of making it impossible to crank. Therefore, accurate information about state of charge (SOC) becomes an essential element for reliable driving. In this paper, a new method of estimating the SOC of lithium polymer batteries by using AC impedance is proposed. In the proposed method, parameters are extracted by fitting a curve of impedance measured at each frequency on the equivalent impedance model and extracted parameters are used to estimate SOC. Experiments were conducted on lithium polymer batteries with similar capacities made by different manufacturers to prove the validity of the proposed method.