• Journal of the Korean Magnetics Society
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• v.4 no.4
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• pp.307-312
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• 1994

The magneto-optical Kerr effect due to the (Fe,Co)/(Pd,Pt,Cu,Ag) multilayer film is calculated considering of multiple reflection effect, and the calculated Kerr spectrum is compared to the reported experimental value. In case of Co/Pd, the reliance of composition and the variable tendency of magneto-optical Kerr rotation angle for Co thickness fully coresponds to experimantal and theoretical value. The theoretical Kerr spectrum of Fe/Cu and Fe/Ag multilayer films show the peaks near the Cu and Ag optical ansorption band in accordance with the experiment. But in case of Co/Pt, the increase tendency of Kerr rofation with decreasing wavelength reported by experiments could not be explained by the optical multiple interference. This difference of theoretical and experimental Kerr spectrum of Co/Pt film might be related with the change of electronic structure of Co and/or Pt from their bulk state.

• Journal of the Korea Institute of Military Science and Technology
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• v.6 no.2
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• pp.73-82
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• 2003

For measurements and analysis of dielectric characteristics of planar slabs of microwave absorbing materials, I have applied a free-space method in the frequency range of 8~14 GHz. The measurement system for free-space method consists of transmit and receive antennas, mode transitions, precision coaxal cables, the network analyzer, and a computer Special Spot-focused horn lens antenna was used to eliminate diffraction effects. Diffraction effects at the edges of the sample are minimized by satisfying the condition for minimum transverse dimension of the plate and the beamwidth of the antennas at the focus. The time-domain gating feature of the network analyzer and the thru, reflect, and line(TRL) calibration technique were used to eliminate the effects of undesirable multiple reflections. The complex coefficients of reflection and transmission, $S_{11}$ and $S_{21}$, of planar samples were measured for standard materials such as Teflon, Rexolite$\textregistered$ 2200. The results were compared with existing measurement method. And I applied a free-space method for measurement to measure dielectric constants of some electromagnetic absorbing materials. Dielectric properties for the same samples were also measured with a 7mm coxial transmission line method for purposes of comparison with the free-space method.

• Korean Journal of Child Studies
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• v.26 no.5
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• pp.217-232
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• 2005

This study examined the effects of an art program based on multiple intelligence theory on children's creativity and spatial ability. The art education program focused on three processes : perception, production and reflection. Subjects were 68 five-year-old children. The experimental design was 'The Untreated Control Group Design with Pretest & Posttest'. ANCOV was employed for statistical analysis. Results were that the children in the experimental group scored significantly higher on creativity and spatial ability than the children in the control group. Results imply that an art education program based on multiple intelligence theory can be an effective teaching model for improving children's creativity and spatial ability.

• Korean Institute of Interior Design Journal
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• v.15 no.2 s.55
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• pp.29-36
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• 2006

This study aims to analyze the multiple meaning of color variously expressed in contemporary architecture. Nowadays heterogeneity, plurality and ephemerality of modem society have been well presented in contemporary architecture. The phenomenal characteristic of color is so appropriate to express the unfixed and immaterialized attributes of contemporary architecture that it can make color a major element of architecture, which, in the past, used to be a minor element for the lack of materiality. Through the analysis of contemporary important building projects in terms of color, it can be concluded that the architectural application of color shows multiple meanings as follows; phenomenal expression, visualization of complex programs and embodiment of design process, reflection of context and control of users' mentality. At the same time, these multiple meanings are complexly presented in a single building project.

• 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.

• Korean Journal of Occupational Health Nursing
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• v.12 no.2
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• pp.134-145
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• 2003

Purpose: The present study examines symptoms of VDT syndrome perceived by those nurses reviewing the application of health insurance at hospitals. This study also investigates those factor influencing on the experience of VDT syndrome among those nurses. Method: Data were collected through mail questionnaire survey in April, 2003. Of the 250 questionnaires disseminated, 214 questionnaires were finally analyzed using descriptive statistics and multiple regression analysis through SPSS/PC version 10.0. Result: Of the VDT syndrome, the musculoskeletal symptom score was highest, followed by ophthalmologic symptoms. The musculoskeletal symptoms were higher among younger nurses, having smaller space under the desk, and feeling uncomfortableness of the chair. The ophthalmologic symptoms were higher among those with a bachelor's degree, younger nurses, and those having a light reflection on the computer monitor, and those maintaining less than 40cm between eyes and the monitor. Higher dermatologic symptoms were observed among younger nurses and those using unclear monitor. The psychological symptoms were higher among younger nurses, those having a light reflection on the monitor, those unable to control the height of their chair, and those using uncomfortable chair. The overall symptoms were higher among younger nurses, those having a light reflection on the monitor, and those smaller space under the desk. Conclusion: Primary intervention should be given to those nurses with symptoms of VDT syndrome in order to regain health and prevent further aggravation of the symptoms. In particular, self-care behaviors of the nurses using VDT should be promoted with administrative support.

• Journal of the Korean Society for Nondestructive Testing
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• v.12 no.1
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• pp.9-15
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• 1992

Ultrasonic spectroscopy is likely to become a very powerful NDE method for detection of microfects and thickness measurement of thin film below the limit of ultrasonic distance resolution in the opaque materials, provides a useful information that cannot be obtained by a conventional ultrasonic measuring system. In this paper, we considered a thin film below the limit of ultrasonic distance resolution sandwitched between two substances as acoustical analysis model, demonstrated the usefulness of ultrasonic spectroscopic analysis technique using information of ultrasonic frequency for measurements of thin film thickness, regardless of interference phenomenon and phase reversion of ultrasonic waveform. By using frequency intervals(${\triangle}f$) of periodic minima from the ratio of reference power spectrum of reflective waveform obtained a sample to power spectrum of multiple reflective waves obtained interference phenomenon caused by ultrasonic waves reflected at the upper and lower surfaces of a thin layer, can measured even dimensions of interest are smaller than the ultrasonic wave length with simplicity and accuracy.

• Current Optics and Photonics
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• v.1 no.3
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• pp.239-246
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• 2017

A compact plasmonic switching scheme, based on the phase change of a thin-film chalcogenide material ($Ge_2Sb_2Te_5$), is proposed and numerically investigated at optical-communication wavelengths. Surface plasmon polariton modal analysis is conducted for various thicknesses of dielectric and phase-change material layers, and the optimized condition is induced by finding the region of interest that shows a high extinction ratio of surface plasmon polariton modes before and after the phase transition. Full electromagnetic simulations show that multiple reflections inside the active region may conditionally increase the overall efficiency of the on/off ratio at a specific length of the active region. However, it is shown that the optimized geometrical condition, which shows generally large on/off ratio for any length of active region, can be distinguished by observing the multiple-reflection characteristic inside the active region. The proposed scheme shows an on/off switching ratio greater than 30 dB for a length of a few micrometers, which can be potentially applied to integrated active plasmonic systems.

• Journal of the Korea Concrete Institute
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• v.15 no.6
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• pp.924-929
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• 2003

A majority of infrastructures has been deteriorated over time. Therefore, it is very important to verify the quality of construction, and the level of structural deterioration in existing structures, to ensure their safety and functionality. Many researchers have studied non-destructive testing (NDT) methods to identify structural problems in existing structures. The impact echo technique is one of the widely used NDT techniques. The impact echo technique has several inherent problems, including the difficulties in P-wave velocity evaluation due to inhomogeneous concrete properties, deterioration of evaluation accuracy where multiple reflection boundaries exist, and the influence of the receiver location in evaluating the thickness of the tested structures. Therefore, the objective of this paper is to propose an enhanced impact echo technique that can reduce the aforementioned problems and develop a Virtual Instrument for the application via a thickness evaluation technique which has same technical background to find deterioration in concrete structures. In the proposed impact echo technique, transfer function from dual channel system analysis is used, and coherence is improved to achieve reliable data. Also an averaged signal -ensemble- is used to achieve more reliable results. From the analysis of transfer function, the thickness is effectively identified.

• Journal of the Society of Naval Architects of Korea
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• v.42 no.5 s.143
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• pp.528-533
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• 2005

A mono-static high frequency acoustic target strength analysis scheme was developed for underwater targets, based on the far-field Kirchhoff approximation. Au adaptive triangular beam method and a concept of virtual surface were adopted for considering the effect of hidden surfaces and multiple reflections of an underwater target, respectively. A test of a simple target showed that the suggested hidden surface removal scheme is valid. Then some numerical analyses, for several underwater targets, were carried out; (1) for several simple underwater targets, like sphere, square plate, cylinder, trihedral corner reflector, and (2) for a generic submarine model, The former was exactly coincident with the theoretical results including beam patterns versus azimuth angles, and the latter suggested that multiple reflections have to be considered to estimate more accurate target strength of underwater targets.