• Proceedings of the Korean Society of Precision Engineering Conference
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• 2013.05a
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• pp.903-904
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• 2013

• Journal of the Optical Society of Korea
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• v.3 no.1
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• pp.10-14
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• 1999

Via THz Time domain spectroscopy, the characterization of high conductive n-type, 1.31Ω cm silicon can be measured by directly analyzing the multiple reflections using Fabry-Perot theory. The magnitude and phase difference of total transmission show good agreement between theoretical and experimental values over a 2.5 THz frequency range with complex index of refraction and power absorption. The measured absorption and dispersion are strongly frequency-dependent, and all of the results are well fit by a Cole-Davidson type distribution.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.22 no.2
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• pp.291-297
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• 1997

A 2.5 Gbp$\times$8 channel WDM signal was transmitted using read-deployed 123 km optical cable around Daejon area. An error free transmission was achieved with $10^{-10}$ criterion, but the receiver sensitivity varied depending on channel, and some channel showed BER floor. The reans was forud to be in reflection points, and the effects of multiple reflections on the ultra high bit transmission was found to be inreflection points, and the effects of multiple reflections on the ultra high bit transmission was analyzed in this paper.

• Journal of Welding and Joining
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• v.23 no.2
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• pp.81-89
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• 2005

A numerical model for multiple reflection effects of a polarized beam on laser grooving has been developed. The surface of the treated material is assumed to reflect laser irradiation in a fully specular fashion. Combining electromagnetic wave theory with Fresnel's relation, the reflective behavior of a groove surface can be obtained as well as the change of the polarization status in the reflected wave field. The material surface is divided into a number of rectangular patches using a bicubic surface representation method. The net radiative flux far these patch elements is obtained by standard ray tracing methods. The changing state of polarization of the electric field after reflection was included in the ray tracing method. The resulting radiative flux is combined with a set of three-dimensional conduction equations governing conduction losses into the medium, and the resulting groove shape and depth are found through iterative procedures. It is observed that reflections of a polarized beam play an important role not only in increasing the material removal rate but also in forming different final groove shapes. Comparison with available experimental results for silicon nitride shows good agreement for the qualitative trends of the dependence of groove shapes on the electric field vector orientation.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2007.11a
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• pp.960-963
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• 2007

In this paper, development of the noise barrier analysis program is described. The upper part of barriers may have complicated shapes like "Y", "T", inverted L, and other shapes. The insertion loss of the barrier is predicted by summation of multiple diffractions occurring at top edge points. In addition, the program considers diffractions occurring at both vertical sides, while reflections from ground due to mirror images are also included. In case of two barriers at both sides of the road, reflections from the other side of barriers are considered, in which magnitudes are decreased by the ratio of absorption coefficient.

• Journal of Electrical Engineering and Technology
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• v.6 no.5
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• pp.693-696
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• 2011

In this work, an exponentially tapered microstrip antenna was implemented using a resistive loading technique in order to suppress the internal reflections. The inductive loading was realized by introducing slits on the antenna to improve radiation efficiency. Compared with a resistive-loaded antenna, the proposed antenna had an average improvement of about 6.2% in radiation efficiency within the range of 2-10.5 GHz. In addition, the highest peak of the radiated short pulse from the proposed antenna became 45% greater than that of an antenna with resistive loading only.

• 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.

• Korean Journal of Mathematics
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• v.25 no.4
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• pp.555-561
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• 2017

We show that a closed curve invariant under inversions with respect to two intersecting circles intersecting at angle of an irrational multiple of $2{\pi}$ is a circle. This generalizes the well known fact that a closed curve symmetric about two lines intersecting at angle of an irrational multiple of $2{\pi}$ is a circle. We use the result to give a different proof of that a compact embedded cmc surface in ${\mathbb{R}}^3$ is a sphere. Finally we show that a closed embedded cmc surface which is invariant under the spherical reflections about two spheres, which intersect at an angle that is an irrational multiple of $2{\pi}$, is a sphere.

• Korean Journal of Family Social Work
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• no.62
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• pp.103-139
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• 2018

The purpose of this study was to explore the social workers' reflections developed during the participatory action research seeking practice methods in the community welfare center single parent self-help groups. Nine social workers and researchers sharing difficulties in the community welfare center single parent self-help group practice were involved in the participatory action research. We performed a circulatory research repeating 'plan-action-reflection-replan' cycles through ten sessions of research meetings including peer supervision in parallel with 4 self-help group practices. Multiple practice methods were derived as the result among which change in the social workers' perception was the key. We focused on the result that the social workers' perception was changed by reflections from participatory action research and the contents of the reflections were qualitatively analyzed using materials acquired during the study. As a result the following 5 themes were derived; 'recognition and worry on the lack of appropriate practice for the self-help group', 'specification of the social workers' role based on the changed perspective on the member-social worker relation', 'confirmation of the possibility of the concerned person initiated practice', 'detailed understanding of the single parent self-help group in the community welfare center', and 'renewed recognition of the development of the single parent self-help group in the community welfare center'. Based on these results, empowerment and reflection/reflective practice for single parent self-help group in the community welfare center were discussed.

• 제어로봇시스템학회:학술대회논문집
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• 2003.10a
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• pp.113-117
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• 2003

The digital systems include the noise in power supply, ground and packaging due to a simultaneous switching of signal, signal reflections and distortions on single and multiple transmission lines. The requirement for the controlled impedance on a PCB can be both a critical success factor and a design challenge. So, the invented tool simulates the tracks controlled impedance with the test coupon. It can saves the design time and supports the economical PCB design.