• Title/Summary/Keyword: multiple reflection

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Diffraction of Electromagnetic Waves by a Dielectric Wedge, Part I: Physical Optics Approximation (쇄기형 유전체에 의한 전자파의 회절, I부 : 물리광학근사)

  • 김세윤;라정웅;신상영
    • Journal of the Korean Institute of Telematics and Electronics
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    • v.25 no.8
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    • pp.874-883
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    • 1988
  • A complete form of physical optics solution to the diffraction of electromagnetic waves by a dielectric wedge with arbitrary dielectric constant and general wedge angle is obtained for an incident plane wave with any angle. Based on the formulation of dual integral equation in the spectral domain, the physical optics solution is constructed by sum of geometrical optics term including multiple reflection inside the wedge and the edge diffracted field, of which diffraction functions are represented in a quite simple form as series of cotangent functions weighted by the Fresnel reflection coefficients. Since diffraction patterns of physical optics are discontinous at dielectric interfaces, Part II and III of these three companion papers will be concerned with correction to the error of the physical optics approximation.

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Mach Reflection of Sinusoidally-Modulated Nonlinear Stokes Waves by a Thin Wedge

  • Choi, Hang-S.;Chee, Won-S.
    • Selected Papers of The Society of Naval Architects of Korea
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    • v.1 no.1
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    • pp.45-51
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    • 1993
  • By using multiple-scale expansion techniques, the Mach reflection of sinusoidally- modulated nonlinear Stokes waves by a stationary thin wedge has been studied within the framework of potential theory. It is shown that the evolution of diffracted wave amplitude can be described by the Zakharov equation to the loading order and that It reduces to the cubic Schrodinger equation with an additional linear term in the case of stable modulations. Computations are made for the cubic Schrodinger equation for different values of nonlinear and dispersion parameters. Numerical results reflect the experimental findings in terms of the amplitude and width of generated stem waves. Based on the computations it is concluded that the nonlinearity dominates the wave field, while the dispersion does not significantly affect the wave evolution.

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Design of Group Delay Time Controller Based on a Reflective Parallel Resonator

  • Chaudhary, Girdhari;Choi, Heung-Jae;Jeong, Yong-Chae;Lim, Jong-Sik;Kim, Chul-Dong
    • ETRI Journal
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    • v.34 no.2
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    • pp.210-215
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    • 2012
  • In this paper, a group delay time controller (GDTC) is proposed based on a reflection topology employing a parallel resonator as the reflection termination. The design equations of the proposed GDTC have been derived and validated by simulation and experimental results. The group delay time can be varied by varying the capacitance and inductance at an operating frequency. To show the validity of the proposed circuit, an experiment was performed for a wideband code division multiple access downlink band operating at 2.11 GHz to 2.17 GHz. According to the experiment, a group delay time variation of $3{\pm}0.17$ ns over bandwidth of 60 MHz with excellent flatness is obtained.

High-Gain and Wideband Microstrip Antenna Using Glass/Epoxy Composite and Nomex Honeycomb (유리섬유/에폭시 복합재료와 허니컴을 이용한 고성능의 마이크로스트립 안테나 설계)

  • You C.S.;Hwang W.
    • Proceedings of the Korean Society For Composite Materials Conference
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    • 2004.04a
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    • pp.1-4
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    • 2004
  • In this paper we developed Composite-Smart-Structures(CSS) using sandwich structure composed of Glass/Epoxy laminates and Nomex honeycomb and microstrip antenna. Transmission/reflection theory shows that antenna performances can be improved due to multiple reflection by Glass/Epoxy facesheet, and honeycomb is used for air gap between antenna and facesheet. Stacked radiating patches are used for the wideband. Facesheet and honeycomb thicknesses are selected considering both wideband and high gain. Measured electrical performances show that CSS has wide bandwidth over $10\%$ and higher gain by 3.5dBi than initially designed antenna, and no doubt it has excellent mechanical performances by sandwich effect given by composite laminates and honeycomb core. The CSS concept can be extended to give a useful guide for manufacturers of structural body panels as well as antenna designers, promising innovative future communication technology.

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Ellipsometric Expressions for a Sample Coated with Uniaxially Anisotropic Layers (단축 이방성 박막들이 코팅된 시료의 타원식)

  • Kim, Sang Youl
    • Korean Journal of Optics and Photonics
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    • v.26 no.5
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    • pp.275-282
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    • 2015
  • The effective reflection coefficients for light obliquely incident upon a substrate coated with uniaxially anisotropic films and with isotropic films are derived. Multiple reflections inside anisotropic films, as well as those inside isotropic films, are properly treated. These expressions, together with the related ellipsometric expressions, can be used to find the nonuniform distribution of an uniaxially anisotropic film perpendicular to the film's surface, by approximating it as consisting of uniaxially anisotropic uniform layers and applying the conventional modeling technique for spectroscopic ellipsometry.

Schur Algorithm for Sub-bottom Profiling (해저지층 탐사를 위한 Schur 알고리즘)

  • Bae, Jinho;Lee, Chong Hyun;Kim, Hoeyong;Cho, Jung-Hong
    • Journal of the Institute of Electronics and Information Engineers
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    • v.50 no.9
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    • pp.156-163
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    • 2013
  • In this paper, we propose an algorithm for estimating media characteristics of sea water and subbottom multi-layers. The proposed algorithm for estimating reflection coefficients, uses a transmitted signal and reflected signal obtained from multiple layers of various shape and structure, and the algorithm is called Schur algorithm. The algorithm is efficient in estimating the reflection coefficients since it finds solution by converting the given inverse scattering problem into matrix factorization. To verify the proposed algorithm, we generate a transmit signal and reflected signal obtained from lattice filter model for sea water and subbottom of multi-level non-homogeneous layers, and then find that the proposed algorithm can estimate reflection coefficients efficiently.

A Study on the Effects and the Countermeasure of Sea Surface Reflection Waves in Pseudolite Navigation Systems (의사위성 항법시스템에서의 해수면 반사파가 미치는 영향 분석 및 대처방안에 대한 연구)

  • Park, Jun-Pyo;Suk, Jinyoung
    • Journal of the Korean Society for Aeronautical & Space Sciences
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    • v.42 no.6
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    • pp.505-514
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    • 2014
  • The effects of reflected wave of the sea on pseudolite ranging accuracy are analysed in this paper, when a pseudolite navigation system is used for wide area outdoor applications such as aircraft and vessels positioning. Methods for minimizing the influence of sea surface reflection wave were proposed. The methods include the appropriate correlator in pseudolite navigation system through the correlation performance comparison analysis in receiver design, the use of the technology of multiple antennas, and locating the transmitting station antenna on an appropriate position. From the results of experiments, the method of locating the antenna position shows the most reliable performance against the effect of surface reflection wave. The analysis results of the ranging accuracy improvement are addressed, when the multipath caused by sea surface reflection exists.

Effects of Clinical Nurses Critical Reflection Competency, Professional Pride, and Person-Centered Care Practice on Patient Safety Management Activities (임상간호사의 비판적 성찰 역량, 전문직 자부심, 인간중심간호 수행이 환자안전간호활동에 미치는 영향)

  • Lee, Subin;Shin, Sujin
    • Journal of Korean Critical Care Nursing
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    • v.16 no.3
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    • pp.87-98
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    • 2023
  • Purpose : This descriptive survey investigated the effects of clinical nurses' critical reflection competency, professional pride, and person-centered care practices on patient safety management activities. Methods : The participants were 183 clinical nurses working at a tertiary hospital in South Korea. The questionnaires consisted of the Critical Reflection Competency Scale for Clinical Nurses Professional Pride the Person-Centered Nursing Assessment Tool and Patient Safety Management Activities. The collected data were analyzed using descriptive statistics, t-tests, ANOVA, Tukey's HSD, Pearson's correlation coefficient, and multiple regression using SPSS 29.0. Results : The mean score for patient safety management activities was 4.65±0.34 out of 5. There were significant differences in patient safety management activities according to age (F=3.90, p =.010), education level (t=-2.56, p =.013), total work experience (F=3.87, p =.010), and the number of healthcare accreditation system experiences (F=5.22, p =.006). Patient safety management activities were positively correlated with critical reflection competency (r=.337, p <.001), professional pride (r=.271, p <.001), and person-centered care practices (r=.399, p <.001). The results indicated that person-centered care practices affected patient safety management activities (𝛽=.358, p <.001) with the explanatory power of 22.5%. Conclusion : To improve clinical nurses' patient safety management activities, it is necessary to develop participatory educational programs that can integrate skills and attitudes based on conceptual knowledge of person-centered care. Intervention studies are needed to test the effect of person-centered care on patient safety when applied in clinical practice.

Removal of Seabed Multiples in Seismic Reflection Data using Machine Learning (머신러닝을 이용한 탄성파 반사법 자료의 해저면 겹반사 제거)

  • Nam, Ho-Soo;Lim, Bo-Sung;Kweon, Il-Ryong;Kim, Ji-Soo
    • Geophysics and Geophysical Exploration
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    • v.23 no.3
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    • pp.168-177
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    • 2020
  • Seabed multiple reflections (seabed multiples) are the main cause of misinterpretations of primary reflections in both shot gathers and stack sections. Accordingly, seabed multiples need to be suppressed throughout data processing. Conventional model-driven methods, such as prediction-error deconvolution, Radon filtering, and data-driven methods, such as the surface-related multiple elimination technique, have been used to attenuate multiple reflections. However, the vast majority of processing workflows require time-consuming steps when testing and selecting the processing parameters in addition to computational power and skilled data-processing techniques. To attenuate seabed multiples in seismic reflection data, input gathers with seabed multiples and label gathers without seabed multiples were generated via numerical modeling using the Marmousi2 velocity structure. The training data consisted of normal-moveout-corrected common midpoint gathers fed into a U-Net neural network. The well-trained model was found to effectively attenuate the seabed multiples according to the image similarity between the prediction result and the target data, and demonstrated good applicability to field data.

Critical Assessment of Programme-Based Conflict Resolution Model Applied to Multiple Stakeholders Within The Context of Industrialized Building Production and Life Cycle Supply Chain System

  • Tanaka, Koji
    • International conference on construction engineering and project management
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    • 2022.06a
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    • pp.551-562
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    • 2022
  • The building production system has been analysed by the dichotomy "employer-contractor" relationship, which failed to take into account of the role and function of multiple stakeholders within the life-cycle supply chain. This is further observed in the current conflict resolution model, which, in my argument, struggles to contribute to industrialize the building production and achieve better efficiency and effectiveness as expected. The purpose of this paper is to critically assess the issues of current programme-based conflict resolution model, and discuss alternative models how they can be modelled and applied to the construction projects. The conclusions of findings are; First, the current model is framed around the contracts and dispute resolutions based on the legal concept of "claimant and respondent" where one party(s) advances a claim once and the other(s) objects, as such it fails to reflect the nature of construction projects where multiple stakeholders are involved concurrently and for a long period of life-cycle of buildings. Second, an alternative is "Six-stakeholders model" which represents the multiple stakeholders and clarifies the flow of obligation-liability-monetary relationships among participants for a long period of life-cycle of buildings. Further, with reference to both historical and recent cases, a reflection and insight into pros and cons of programming method is added, especially as to why this method is considered to have become a mandate of the modern construction management, and how academics and practitioners should deal with it more cautiously and prudently.

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