• Proceedings of the Korean Operations and Management Science Society Conference
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• 2006.11a
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• pp.316-319
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• 2006

통신대역폭 거래(Bandwidth Trading, BT)는 국제적으로 1 조 달러 이상의 잠재적 시장을 보유한 사업 분야로, 특히 통신사업자에게는 비용절감과 새로운 수익창출의 기회를 제공한다. 그러나 아직까지 BT 에 대한 체계적인 연구는 국내/외를 막론하고 초기단계에 있다. 본 논문은 먼저 차세대 All-IP 인프라 환경에서 통신대역폭이 상품화되는 경향을 살펴본다. 또한 BT 허브(exchange hub) 역할을 할 제 3자 기반의 BTS(BT System)을 제안한다. 마지막으로 제안된 BTS 환경에서 통신사업자의 수입을 극대화하는 BTE(BT Engine)을, Markov 의사결정모형을 적용하여 개발한다.

• Journal of IKEEE
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• v.14 no.1
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• pp.47-54
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• 2010

In this study, we analyzed the reduction of noise in a noise environment using 2, 3, 4 or 5 microphones in digital hearing aids. In order to be able to use this in actual digital hearing aids, we made the experiment microphone set similar to the behind-the-ear type (BTE) and then recorded the signal accordingly, with each situation. With the recorded signals, we reduced the noise in each signal by a noise reduction algorithm using multi-microphones. As a result, in the case of By comparing the SNR (Signal to Noise Ratio) and PESQ (Perceptual Evaluation of Speech) measurements, before and after the noise reduction, the results showed that the improvement in performance was highest when three or four microphones were used. Generally, when two or more microphones were used, we found that as the number of microphones increased there was an increase in performance.

• Korean Security Journal
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• no.21
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• pp.1-18
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• 2009

Background: This study was to investigate the effects of spinal strengthening exercise and lumbar stabilization exercise(core exercise program) on trunk muscle strength, flexibility and balance, lumbar function. The subjects of this study were the eighteen subjects who was registered in private guard company. The each exercise group of 9 persons were chosen by random controlled trial. Methods: We used instrument BTE, Libra, Ruler Measuring tape to measured trunk muscle strength, flexibility, balance and lumbar function. Results: The result of this study were summarized below; The flexor muscle strength was improve in lumbar stabilization exercise(core exercise) group(p<.05). The extensor muscle strength was improve in lumbar stabilization exercise(core program) group(p<.05). The trunk flexibility was improve in spinal strengthening exercise group and lumbar stabilization exercise group(p<.05). The balance ability was improve in spinal strengthening group and lumbar stabilization exercise group(core program) group(p<.05). Conclusion: With the above results, demonstrated effects of spinal strengthening exercise and lumbar stabilization exercise in each private guard and security in this study.

• Nuclear Engineering and Technology
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• v.51 no.8
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• pp.2005-2012
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• 2019

This work investigated the radiation attenuation characteristics of three series of tellurite glass systems with the following compositions: 30PbO-10ZnO-xTeO₂-(60-x)B₂O₃ where x = 10, 30, 40, 50 and 60 mol%, xBaO-xB₂O₃-(100-2x)TeO₂ with x = 15-40 mol% and 50ZnO-(50-x)P₂O₅-xTeO₂, where x = 0, 10, .40 mol%. The results revealed that the attenuation parameters in all the samples decrease with increase in the energy, which implied that all the samples have better interaction with gamma photons at low energies and thus higher photon attenuating efficiency. From the three systems, the samples coded as PbZnBTe60, BaBTe70 and ZnPTe40 have the lowest half value layer values and accordingly have superior photon attenuation efficacy. The maximum effective atomic number values were found for energy less than 0.1 MeV particularly near the K-edges absorption of the heavy atomic number elements such as Te, Ba and Pb. At the lowest energy, the Z_eff values are found in the range of 62.33-66.25, 49.43-50.81 and 24.99-35.83 for series 1-3 respectively. Also, we found that the density of the glass remarkably affects the photon attenuation ability of the selected glasses. The mean free path results showed that the PbO-ZnO-TeO₂-B₂O₃ glass system has better radiation shielding efficiency than the glass samples in series 2 and 3.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.30 no.2 s.245
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• pp.117-125
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• 2006

In the present study the unsteady forces acting on the pitching foils such as a flat plate, NACA0010, NACA0020, NACA65-0910 and BTE have been measured by using a six-axis sensor in a circulating water tunnel at a low Reynolds number region. The unsteady characteristics of the dynamic drag and lift have been compared to the quasi-steady ones which are measured under the stationary condition. The pitching motion is available for keeping the lift higher after the separation occurs. Especially, the characteristics of the dynamic lift are quite different from the quasi-steady one at high pitching frequency regions. As the pitching frequency deceases, the amplitude of the dynamic lift becomes closer to the quasi-steady one. However, the phase remains different between the steady and unsteady conditions even at low pitching frequencies. On the other hand, the dynamic drag is governed strongly by the angle of attack.

• Proceedings of the KSME Conference
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• 2007.05b
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• pp.2182-2187
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• 2007

The relative contributions of phonon and electron to the thermal conductivity of silicon film with varying doping density are evaluated from the modified electron-phonon interaction model, which is applicable to the micro/nanoscale simulation of energy transport between energy carriers. The thermal conductivities of intrinsic silicon layer thicknesses from 20 nm to 500 nm are calculated and extended to the variation in n-type doping densities from 1.0 ${\times}$ $10^{18}$ to 5.0 ${\times}$ $10^{20}$ $cm^{-3}$, which agree well with the experimental data and theoretical model. From simulation results, the phonon and electron contributions to thermal conductivity are extracted. The electron contribution in the silicon is found to be not negligible above $10^{19}$ $cm^{-3}$, which can be classified as semimetal or metal by the value of its electrical resistivity at room temperature. The thermal conductivity due to electron is about 57.2% of the total thermal conductivity at doping concentration 5.0 ${\times}$ $10^{20}$ $cm^{-3}$ and silicon film thickness 100 nm.

• Journal of the Institute of Electronics Engineers of Korea SD
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• v.39 no.2
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• pp.27-38
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• 2002

A new self-consistent mathematical model for semiconductor quantum well device was developed. The model was based on the direct solution of the Boltzmann transport equation, coupled to the Schrodinger and Poisson equations. The solution yielded the distribution function for a two-dimensional electron gas(2DEG) in quantum well devices. To solve the Boltzmann equation, it was transformed into a tractable form using a Legendre polynomial expansion. The Legendre expansion facilitated analytical evaluation of the collision integral, and allowed for a reduction of the dimensionality of the problem. The transformed Boltzmann equation was then discretized and solved using sparce matrix algebra. The overall system was solved by iteration between Poisson, Schrodinger and Boltzmann equations until convergence was attained.

• Journal of the Korean Society of Clothing and Textiles
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• v.8 no.2
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• pp.27-40
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• 1984

Die Geschichte des Kostums steht in unmittelbarem odor mittelbarem Zusammenhang mit der allgemeinea historischen Entwicklung derjenigen Lander und sozialen Schichten, die das kulturclle Gesicht und damit auch die Entwicklung der Mode einer Epoche bestimmen. Im 19. Jahrhundert war das Burgertum in Europa die herrschende soziale Schicht und daher auch modisch tonangebend. Die Mode des Burgertums zeigte demokratisierende Tendon-zen: Vereinfachung der Ausstattung und der Formen, wobei sich die Proportionen der Kleidung so gut wie moglich den des Korpers anpaBten. Die Herrenmode beugte sich zunehmend den For-derungen nach ZweckmaBigkeit; dab galt zumindest fur den Tagesanzug, der immer mehr zum Arbeitsanzug wurde und sick damit der Mannerkleidung der arbeinden Schicht annahrte. Die Industrialisierung trug ebenfalls dazu bei, daB die modischen und sozialen Previlegien in der Kleidung sich verminderten : die Textil-und Konfektionsindustrie muBte sich zwangs-laufig auf die Bedurfnisse der Massen und auf deren Wunsch einstellen. In der Herrenmode setzte sich die Tendenz zu funktionaler Einfachheit und Gradlinigkeit durch, d.h. funktional uberflussige Teile wie z.B. die Vielzahl der Kragen, Knopfreihen, uberlange SchoBe verschwanden ; an die Stelle der Farbenfreude trat ein einfaches, einhei-tliches Grau, Schwarz, Blau und Braun. Diese Vereinfachung wurde zum Ausdruck der zunehmenden Demokratisierung, wurde aber zugleich auch Voraussetzung fur eine neue Differnzierung des KlassenbewuBtseins. Zum Statussymbol wurden die auffalliges Erscheinen vermeidende Eleganz und das Arrangement der einzelnen Kleidungsstucke zu einem har-monischen Ganzen; elegante Kleidung weist ihren Trager aus als Kenner des Modetrends und damit als zugehorig zum Kreis der modeavancierten Schicht. Diese Ambivalenz bestimmt auch die Mode des 20. Jahrhunderts.

• Journal of the Korean Society of Physical Medicine
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• v.7 no.4
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• pp.493-500
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• 2012

PURPOSE: The purpose of this study was to investigate effect of self-controlled feedback on proprioception in elbow flexion. METHODS: Thirty young adult volunteered to participate and were randomly assigned to one of three groups (self-controlled, yoked, control). Power and velocity in elbow flexion was measured by PRIMUS RS (BTE Tech., Hanover, U.S.A). Statistical analysis was used multivariate ANOVA to know effect of self-controlled feedback on proprioception in elbow flexion. Post hoc was used Scheffe. RESULTS: In acquisition phase to practice effect, variable errors in self-controlled group was significantly low scored more than yoked and control group. In retention phase to learning effect, variable errors in self-controlled group was significantly low scored more than yoked and control group. CONCLUSION: Self-controlled feedback was more effective on movement control when the learner could make a decision about receiving feedback after the trial. This seems to support the view that self-controlled feedback benefits learning, because learners can make a decision about feedback based on their performance on a given trial.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.56 no.2
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• pp.367-373
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• 2007

The present study investigates numerically nonequilibrium energy transfer between electrons and phonons in metal thin films irradiated by ultrashort pulse lasers and it also provides the temporal and spatial variations of electron and phonon temperatures using the well-established two-temperature model(TTM) on the basis of the Boltzmann transport equation(BTE). This article predicts the crater shapes in gold film structures, and compares the results by using two-dimensional energy transport equation. From the results, it is found that nonequilibrium energy transfer between electrons and phonons takes place, and the equilibrium time increases with the increase of laser fluence. On the other hand, above threshold fluence the ablation time doesn't change nearly with increasing fluences. Compared with one-dimensional TTM, it also reveals that the temporal distributions of electron and phonon temperatures at the top surface estimated by using two-dimensional TTM have a similar tendency. The results show that two-dimensional TTM can simulate the crater shape of metals during the irradiation of femtosecond pulse lasers and the absorbed energy is propagated to z-direction faster than to r-direction.