• Geomechanics and Engineering
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• v.18 no.3
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• pp.259-266
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• 2019

This paper presents a comparison between experimental measurements and numerical estimations of penetration length of a cement grout injected in discrete joints. In the experiment, a joint was generated by planar acryl plates with a certain separation distance (; aperture) and was designed in such a way to vary the separation distances. Since a cement grout was used, the grout viscosity can be varied by controlling water-cement (W/C) ratios. Throughout these experiments, the influence of joint aperture, cement grout viscosity, and injection rate on a penetration length in a discrete joint was investigated. During the experiments, we also measured the time-dependent variation of grout viscosity due to a hardening process. The time-dependent viscosity was included in our numerical simulations as a function of elapsed time to demonstrate its impact on the estimation of penetration length. In the numerical simulations, Bingham fluid model that has been known to be applicable to a viscous cement material, was employed. We showed that the estimations by the current numerical approach were well comparable to the experimental measurements only in limited conditions of lower injection rates and smaller joint apertures. The difference between two approaches resulted from the facts that material separation (; bleeding) of cement grout, which was noticeable in higher injection rate and there could be a significant surface friction between the grout and joint planes, which are not included in the numerical simulations. Our numerical simulation, meanwhile, could well demonstrate that penetration length can be significantly over-estimated without considering a time-dependency of viscosity in a cement grout.

• Journal of Aerospace System Engineering
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• v.16 no.3
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• pp.99-104
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• 2022

Aircraft pylon connects the engine or external stores to the main wing, and transfers the load acting on the pylon to the main structure of the aircraft. In particular, it should perform the function of separating the external store mounted on the pylon in case of emergency or mission performance. At this time, if the separation of the external store is not performed properly due to peripheral air flow or functional problems during the separation process of the external store, it may seriously impact the survivability of the aircraft. For this reason, to apply an external attachment to an aircraft, it is necessary to prove the stability of the external attachment in the separation situation in advance. In this paper, we present the result of the ground separation test performed to confirm that the external fuel tank, which is an external attachment, can be safely separated from the pylon. As a result of the test, the separation movement of the external fuel tank was measured with a high-speed camera, and the stability of the separation of the external fuel tank from the pylon were confirmed through the ground separation test. Additionally, the test result provides basic data for the stability evaluation of the separation of external attachments in actual aircraft.

• Journal of Information Display
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• v.11 no.1
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• pp.24-27
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• 2010

A novel stereo 3D LCD for passive interference filter glasses is presented. A demonstrator based on a standard 120Hz LCD was set up. Stereoscopic image separation was realized in a time-sequential mode using a LED-based scanning backlight with two complementary spectra. A stereo brightness of 3 cd/$m^2$ and a channel separation of 30:1 were achieved.

• Proceedings of the IEEK Conference
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• 2006.06a
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• pp.365-366
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• 2006

This paper describes a pre-processing methodology which can apply to remote speech recognition system of service robot in noisy environment. By combining beamforming and blind source separation, we can overcome the weakness of beamforming (reverberation) and blind source separation (distributed noise, permutation ambiguity). As this method is designed to be implemented with hardware, we can achieve real-time execution with FPGA by using systolic array architecture.

• Proceedings of the IEEK Conference
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• 2002.07c
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• pp.1827-1830
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• 2002

A matrix pencil method for source separation 〔3〕was shown to be an unbiased signal extractor in the presence of temporally white noise. Its efficiency and robustness lies in the fact that the method in 〔3〕 employs only time-delayed correlation matrices of the observation data, In this paper we stress out that the matrix pencil method might suffer from a numerical instability problem, be- cause the symmetric-definite pencil was not exploited. Moreover we present a simple method of constructing a symmetric-definite pencil so that the matrix pencil method is numerically stable.

• Proceedings of the Membrane Society of Korea Conference
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• 2004.05a
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• pp.3-6
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• 2004

Industrial gas separation by membranes began in 1980 with the introduction of hollow-fiber polysulfone membrane systems by Permea, at that time a division of Monsanto. This first application was the recovery of hydrogen from ammonia reactor purge gas and was soon followed by the generation of nitrogen from air. Today, membrane gas separation ranks second behind cryogenic distillation in terms of nitrogen production, and this application has drawn the industrial gas companies into the membrane field.(omitted)

• Proceedings of the Korean Information Science Society Conference
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• 2004.10a
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• pp.25-27
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• 2004

독립적인 여러 개의 음원의 convoultive mixture로부터 blind source separation(BSS)을 수행하는 것은 수년간 활발히 연구되어 오고있다. 그러나 많은 BSS 알고리즘이 존재함에도 불구하고, 직접적으로 하드웨어를 구현할 수 있는 알고리즘은 실제로 매우 드물다. 이 논문의 목표는 FPGA를 이용하여 실시간으로 효과적인 구현이 가능한 BSS 구조를 소개하는 것이다.

• The Journal of the Korea institute of electronic communication sciences
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• v.10 no.10
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• pp.1101-1108
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• 2015

In this paper, to provide a method and system for providing a network separation virtual machine environment. How to provide this virtual machine environment include phase generating necessary virtual resource requirement for the perform of virtual function and transfer to network changing protocol about request of registration virtual resource. For this reason, Registration procedure is to use a virtual machine for a virtual computing resource allocation and separation combined network any time, it became possible between servers and clients, or mobile phone. At any time, it is possible to process the work in the same environment as in a computer to access the Internet.

• Proceedings of the KIEE Conference
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• 2003.10a
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• pp.286-289
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• 2003

We investigated the influence of the properties of substrate material on the separation efficiency in microchip electrophoresis. We fabricated the various microchips and studied separation efficiency in microchannels composed of a single material such as quartz, glass, polydimethylsiloxane (PDMS), and polymethylmetha crylate (PMMA), as well as hybrid micro channels composed of different materials. New fabrication process for glass chip was suggested and some treatment is added to improve fabrication process in other chip. Separation efficiency was compared by measuring migration times and bandwidths of EOF and analytes in each microchip. The efficiency is the function of migration time, which is affected by the electroosmotic flow (EOF), and bandwidth of an analyte. EOF is highly dependent upon the characteristics of a microchannel wall surface. Migration time was more reproducible in silica chips than that of PDMS chip and more band broadening was observed in the microchip composed of hybrid material due to non-uniformity of surface charge density at the walls of the channel.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.5
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• pp.19-29
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• 2006

In this study, numerical simulation of airframes separating from a missile system has been preformed. For the time-accurate trajectory simulation, six D.O.F equations of motion of multiply connected bodies were derived and these equations have been coupled with the unstructured overset mesh technique for the treatment of independent mesh blocks moving with each body component. Applications were made for the simulation of the airframe separation at missile angles of attack of 0 and 5 degrees. It was demonstrated that the present method is efficient and robust for the prediction of unsteady time-accurate flow fields involving multiple bodies in relative motion.