• Structural Engineering and Mechanics
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• 제44권5호
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• pp.585-600
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• 2012

This paper presents a Modified Tikhonov Regularization (MTR) method in model updating for damage identification with model errors and measurement noise influences consideration. The identification equation based on sensitivity approach from the dynamic responses is ill-conditioned and is usually solved with regularization method. When the structural system contains model errors and measurement noise, the identified results from Tikhonov Regularization (TR) method often diverge after several iterations. In the MTR method, new side conditions with limits on the identification of physical parameters allow for the presence of model errors and ensure the physical meanings of the identified parameters. Chebyshev polynomial is applied to approximate the acceleration response for moderation of measurement noise. The identified physical parameter can converge to a relative correct direction. A three-dimensional unsymmetrical frame structure with different scenarios is studied to illustrate the proposed method. Results revealed show that the proposed method has superior performance than TR Method when there are both model errors and measurement noise in the structure system.

• Journal of Computing Science and Engineering
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• 제8권2호
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• pp.65-77
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• 2014

To address the problem of multi-target retrieval (MTR) of remote sensing images, this study proposes a new object-level feature representation model. The model provides an enhanced application image representation that improves the efficiency of MTR. Generating the model in our scheme includes processes, such as object-oriented image segmentation, feature parameter calculation, and symbolic image database construction. The proposed model uses the spatial representation method of the extended nine-direction lower-triangular (9DLT) matrix to combine spatial relationships among objects, and organizes the image features according to MPEG-7 standards. A similarity metric method is proposed that improves the precision of similarity retrieval. Our method provides a trade-off strategy that supports flexible matching on the target features, or the spatial relationship between the query target and the image database. We implement this retrieval framework on a dataset of remote sensing images. Experimental results show that the proposed model achieves competitive and high-retrieval precision.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1999년도 추계학술대회 논문집 학회본부 A
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• pp.318-321
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• 1999

This paper describes the study of the effect on real power system due to the inclusion of the MTR at Buk Che-ju TP #2. The test system in which the transformers are represented in detail and rest Che-ju systems are represented as an equivalent system on the bus is simulated by the EMTDC. Simulation results include magnitude of inrush current and voltage drop on the bus at various CB closing time, and they show the effect on Che-ju system by the inrush current of the Buk Che-ju TP #2's MTR is not considerable.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.1561-1565
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• 2008

More than 3.4 million people use Hong Kong metro a day. It was first constructed in 1979, and extended to 9 operating lines with 168.1km length operated by Hong Kong Mass Transit Railway Corporation (MTR). In Hong Kong, airborne viruses such as avian influenza (bird's flu) and severe acute respiratory syndrome (SARS), air pollution by high-density traffics, bacteria and mold due to relatively high humidity are major concerns on air quality management. In this study, we focused on the cases for improving indoor air quality conducted by Hong Kong MTR currently. The case includes the photocatalytic coatings on knobs (or hand straps) to prevent outbreak of bird's flu and SARS, the high voltage ionizers installed at metro platform, and the periodical radon monitoring.

• 말소리와 음성과학
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• 제6권2호
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• pp.29-34
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• 2014

In the Vector Taylor Series (VTS)-based noisy speech recognition methods, Hidden Markov Models (HMM) are usually trained with clean speech. However, better performance is expected by training the HMM with noisy speech. In a previous study, we could find that Minimum Mean Square Error (MMSE) estimation of the training noisy speech in the log-spectrum domain produce improved recognition results, but since the proposed algorithm was done in the log-spectrum domain, it could not be used for the HMM adaptation. In this paper, we modify the previous algorithm to derive a novel mathematical relation between test and training noisy speech in the cepstrum domain and the mean and covariance of the Multi-condition TRaining (MTR) trained noisy speech HMM are adapted. In the noisy speech recognition experiments on the Aurora 2 database, the proposed method produced 10.6% of relative improvement in Word Error Rates (WERs) over the MTR method while the previous MMSE estimation of the training noisy speech produced 4.3% of relative improvement, which shows the superiority of the proposed method.

• 대한전기학회:학술대회논문집
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• 대한전기학회 2003년도 추계학술대회 논문집 전력기술부문
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• pp.345-347
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• 2003

본 논문에서는 분산전원이 기존의 배전계통상에 도입되는 경우에 대하여 전압변동해석을 수행하기 위하여, 풍력발전단지가 도입된 제주 성산 변전소를 선정하여 MATLAB 프로그램을 이용하여 시뮬레이션을 수행하고 전압변동상황을 예측, 이에 따른 문제점과 그에 대한 대책을 제시하도록 할 것이다.

• Korean Chemical Engineering Research
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• 제46권5호
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• pp.931-937
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• 2008

공정변수의 변화와 반응기의 성능을 정확하게 예측하기 위하여 Water Gas Shift Reaction(WGSR)을 위한 Multi-Tubular Reactor (MTR)의 상세 multiscale 모델링과 모사를 수행하였다. MTR은 비 균일 고체 촉매로 충진 된 4개의 관형반응기와 냉각을 위해 주변을 싸고 있는 shell side로 구성되어 있다. 유체의 흐름과 반응 kinetics가 반응기 성능에 큰 영향을 주고 있는 점을 고려할 때, Computational Fluid Dynamics (CFD)기법과 공정모델링 기법을 포함한 multiscale 방법론의 채택은 자연스럽고 필수 불가결한 일이다. $345^{\circ}C$로 관형반응기 부분으로 유입된 반응물은 반응의 결과 $390^{\circ}C$로 $45^{\circ}C$가량 온도가 증가하였으며, CO의 전환율은 0.89에 이르렀다. 쉘 사이드로 $190^{\circ}C$로 유입된 유체는 쉘 출구에서 $240^{\circ}C$로 약 $50^{\circ}C$ 가량의 온도 증가를 보였으며 이를 통하여 에너지 절감효과를 가져 올 수 있었으며 높은 전환율을 얻기 위해 반응기 부분의 온도를 적절히 제어할 수 있었다. 모사의 결과는 여러 문헌에 보고된 실험 결과와 매우 근접한 값을 나타내 본 연구를 통해 제시된 모델과 모사의 결과가 정확함을 알 수 있었다.

• International Journal of Contents
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• 제7권2호
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• pp.59-63
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• 2011

The aim of our study was to evaluate the immediate effects of an 830-nm Aluminium gallium arsenide (GaAlAs) laser, by examining the changes, in pressure-pain threshold (PPT) and tenderness at 3 kg of the myofascial trigger point (MTrP) of the upper trapezius muscle in visual display terminal (VDT) workers in comparison with placebo treatment. Thirty VDT workers (13 males, 17 females) with complaints of upper trapezius muscle were recruited. All participants were given either active GaAlAs laser (830 nm wavelength, 450 mW, 9 J at point) or placebo GaAlAs laser, according to the double-blinded and placebo-controlled trial. Both active and placebo low-level laser therapy (LLLT) treatments showed no significant effect on PPT and tenderness at 3 kg. These results suggest that a higher dosage may be necessary to produce immediate effects when applying LLLT to the MTrP of relatively large muscles such as the upper trapezius muscle.

• Nuclear Engineering and Technology
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• 제49권5호
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• pp.953-967
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• 2017

In this paper, a complete station blackout (SBO) or complete loss of electrical power supplies is simulated and analyzed in a downward cooling 5-MW pool-type Material Testing Reactor (MTR). The scenario is traced in the absence of active cooling systems and operators. The code nodalization is successfully benchmarked against experimental data of the reactor's operating parameters. The passive heat removal system includes downward water cooling after pump breakdown by the force of gravity (where the coolant streams down to the unfilled portion of the holdup tank), safety flapper opening, flow reversal from a downward to an upward cooling direction, and then the upward free convection heat removal throughout the flapper safety valve, lower plenum, and fuel assemblies. Both short-term and long-term natural core cooling conditions are simulated and investigated using the RELAP5 code. Short-term analyses focus on the safety flapper valve operation and flow reversal mode. Long-term analyses include simulation of both complete SBO and long-term operation of the free convection mode. Results are promising for pool-type MTRs because this allows operators to investigate RELAP code abilities for MTR thermal-hydraulic simulations without any oscillation; moreover, the Tehran Research Reactor is conservatively safe against the complete SBO and long-term free convection operation.

• Nuclear Engineering and Technology
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• 제53권9호
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• pp.2847-2858
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• 2021

When a nuclear reactor with rectangular fuel assemblies runs for a long time, impurities and debris may be taken into coolant channels, which may cause flow blockage, and the blocked fuel assemblies might be destroyed. Therefore, the purpose of this study is to perform a thermal-hydraulic analysis of a rectangular fuel assembly by STAR-CCM+, under the condition of one subchannel with 80% blockage ratio. A rectangular fuel assembly of the International Atomic Energy Agency (IAEA) 10 MW material test reactor (MTR) is chosen. In view of the gasket material taken into the coolant channel is close to the single side of the coolant channel, in the flow blockage accident of the Oak Ridge Research Reactor (ORRR), a new blockage category called single side blockage is attempted. The blockage positions include inlet, middle and outlet, and the blockage is set as a cuboid. It is found by simulations that the blockage redistributes the mass flow rate, and large vortices appear locally. The peak temperature of the cladding is maximum, when the blockage is located at the single side of the coolant channel inlet, and no boiling occurs in all blockage cases. Moreover, as the height of the blockage increases, the damage caused by the blockage increases slightly.