• Journal of the Society of Naval Architects of Korea
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• v.44 no.4
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• pp.445-450
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• 2007

An optimum design process of the broad-band multi-layered radar absorbing material, using genetic algorithm, is established for the radar cross section reduction of a complex target, which consists of multiple reflection structures, such as surface warships. It follows the successive process of radar cross section analysis, scattering center analysis, radar absorbing material design, and reanalysis of radar cross section after applying the radar absorbing material. It is demonstrated that it is very effective even in the optimum design of the multi-layer radar absorbing material. This results from the fact that the three factors, i.e.. the incident angle range, broad-band frequencies, and maximum thickness can be simultaneously taken into account by adopting the genetic algorithm.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2002.11b
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• pp.699-704
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• 2002

A method using beamforming algorithm has been developed to measure oblique incidence reflection coefficients of sound absorption materials. MUSIC(Multiple Signal Classification) method detects the angles of incidence and reflection. By separating the incident and reflected waves using beamforming method, the reflection coefficient is calculated. Spatial smoothing technique is also used to reduce the coherence between the incident and reflected waves. The test materials were modeled as a locally reacting surface. Numerical and experiment results are performed to verify the acuracy of proposed method.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.6
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• pp.438-444
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• 2003

A method using beamforming algorithm has been developed to measure oblique incidence reflection coefficients of sound absorption materials. MUSIC(multiple signal classification) method detects the angles of incidence and reflection. By separating the incident and reflected waves using beamforming method, the reflection coefficient is calculated. Spatial smoothing technique Is also used to reduce the coherence between the incident and reflected waves. Numerical and experiment results are performed to verify the accuracy of proposed method.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.18 no.2
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• pp.97-111
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• 2006

Using the eigenfunction expansion method, a mathematical model has been developed to calculate the reflection and transmission of regular waves from a multiple-row curtainwall-pile breakwater. In addition, hydraulic model experiments have been conducted with different values of porosities between the piles, drafts of the curtain walls, and distances between the rows of the breakwater. It is found that the reflection and transmission coefficients decrease and increase, respectively, with decreasing relative water depth, but they bounce to increase and decrease, respectively, as the relative water depth decreases further. When either the porosity between the piles or the draft of the curtain wall is changed with other parameters fixed, the relative magnitudes of the reflection and transmission coefficients have been changed, but the general trend remained the same. When the wavelength is the same as the distance between the rows of the breakwater, a rapid change was observed for the reflection and transmission coefficients. A good agreement between the measurement and prediction was also founded for three-row breakwaters.

• Journal of Digital Convergence
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• v.14 no.12
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• pp.345-355
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• 2016

As Korea has been rapidly transformed to be a multi cultural society, it becomes essential for nursing provider to develop cultural competency. The purpose of this study was to identify impact of self-reflection, critical thinking disposition and multi cultural experience on nursing student's cultural competence. A convenience sample of 148 nursing students was obtained from a university in Gyeonggi Province. Data was analyzed using Pearson correlation and multiple regression. Significant relationships were found between self-reflection, critical thinking disposition, multi cultural experience and cultural competence in nursing student. The result of multiple regression indicates that critical thinking disposition (${\beta}=0.27$, p=.005), self-reflection (${\beta}=0.21$, p=.040) were the most consistent predictors of cultural competence and explained 26.0%. Thus, it is necessary to develop multi cultural education program including self-reflection and critical thinking disposition. The findings suggest the necessity to explore further various factors affecting the cultural competence and to conduct research for establishment a theoretical model.

• Korean Journal of Optics and Photonics
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• v.14 no.3
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• pp.286-291
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• 2003

Asymmetric multiple quantum well ridge waveguide laser diodes (AMQW RWG LDs) with a wide and flat gain spectrum were designed and fabricated. The operating parameters and gain spectra were measured and analyzed for uncoated and anti-reflection (AR) coated LDs. For AR coated 500 mm-long RWG LOs, the extremely flat gain spectrum over a spectral range of 90 nm was obtained at the current 75 ㎃.

• Proceedings of the Korean Magnestics Society Conference
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• 2003.12a
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• pp.140-140
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• 2003

• Proceedings of the KWS Conference
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• 2006.05a
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• pp.51-52
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• 2006

• Journal of East-West Nursing Research
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• v.26 no.2
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• pp.176-184
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• 2020

Purpose: The purpose of this study was to investigate the influence of nursing students' self-reflection and insight, and academic selfefficacy on their clinical reasoning competence. Methods: Data were collected from 147 third- and fourth-year nursing students who had more than 6 months of clinical training experience. Clinical reasoning competence, self-reflection and insight, and academic self-efficacy were measured using self-reported questionnaires. Data analysis was conducted with IBM SPSS 25.0 using one-way ANOVA, independent t-test, Pearson correlation coefficient, and multiple regression analysis. Results: Clinical reasoning competence was positively correlated with self-reflection and insight (r=.24, p=.003) and academic self-efficacy (r=.30, p<.001). Academic self-efficacy (β=.23, p=.011), dissatisfaction with major (β=-.17, p=.034), and 5~8 case studies (β=-.39, p=.027) were identified as factors influencing clinical reasoning competence (adjusted R²=.15). Conclusion: To improve the clinical reasoning competence of nursing students, it is necessary to develop the academic self-efficacy of complex cases and provide critical inquiries, debriefing tailored to clinical reasoning, and sufficient reflection during clinical and simulation practice.

• Transactions of the Korean hydrogen and new energy society
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• v.29 no.2
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• pp.163-169
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• 2018

The present article discusses about the measurement techniques of acoustic impedance that becomes one of the important acoustic characteristics of various boundaries found inside of propulsion systems. Acoustic characteristics including acoustic impedance and reflection coefficient can be often assessed and estimated by use of the two-microphone method. Theoretical expressions of acoustic impedance and reflection coefficient measured in an impedance tube are presented for both cases with mean flow and without flow, and the practical application of the method through calibration is also provided. The acoustic impedance and the reflection coefficient are related with axial locations of microphones, thermodynamic characteristics of gas inside, and the transfer function between the pressure wave measurements at multiple locations.