• The Journal of the Acoustical Society of Korea
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• 제29권2호
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• pp.97-101
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• 2010

FIR type system identification with noisy input and output data can be solved by a total least squares (TLS) estimation. However, the performance of the TLS estimation is very sensitive to the ratio between the variances of the input and output noises. In this paper, we propose an iterative convex combination algorithm between TLS and least squares (LS). This combined algorithm shows robustness against the noise variance ratio. Consequently, the practical workability of the TLS method with noisy data has been significantly broadened.

• KSCE Journal of Civil and Environmental Engineering Research
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• 제32권1B호
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• pp.9-20
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• 2012

Recently to overcome limitations of conceptual, hydrological and physics based models for flood stage forecasting, multiple linear regression model as one of data-driven models have been widely adopted for forecasting flood streamflow(stage). The objectives of this study are to compare performance of different multiple linear regression models according to regression coefficient estimation methods and determine most effective multiple linear regression flood stage forecasting models. To do this, the time scale was determined through the autocorrelation analysis of input data and different flood stage forecasting models developed using regression coefficient estimation methods such as LS(least square), WLS(weighted least square), SPW(stepwise) was applied to flood events in Jungrang stream. To evaluate performance of established models, fours statistical indices were used, namely; Root mean square error(RMSE), Nash Sutcliffe efficiency coefficient (NSEC), mean absolute error (MAE), adjusted coefficient of determination($R^{*2}$). The results show that the flood stage forecasting model using SPW(stepwise) parameter estimation can carry out the river flood stage prediction better in comparison with others, and the flood stage forecasting model using LS(least square) parameter estimation is also found to be slightly better than the flood stage forecasting model using WLS(weighted least square) parameter estimation.

• Journal of the Korean Society of Systems Engineering
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• 제8권2호
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• pp.11-17
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• 2012

Suppliers in light rail transit project makes a systems engineering management plan(SEMP) as a top level plan which has a SEMS and SEDS as an control and monitoring means. In this paper, we analyze the international standards and some related documents, and present the directions to make the SEMS and SEDS which have WBS, accomplishments, schedule, events, person in charge. And then customize the project management tool and make SEMS and SEDS of LRT project as an example. The research results can be applied in LRT project after tailoring based on the project.

• Polymer(Korea)
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• 제25권6호
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• pp.848-854
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• 2001

The crystallization behavior of poly (ethylene terephthalate) (PET) /ethylene-methyl acrylate-glycidyl methacrylate copolymer (E-MeA-GMA) blend was studied. The extent of reaction and the reaction rate between PET and E-MeA-GMA were measured with torque rheometer, FT-IR and SEM. The effects of the grafting reaction on the crystallization behavior were investigated with DSC and time-resolved light scattering (TR-LS) techniques. The morphological change at the lamellar level was also examined by using a small angle X-ray scattering (SAXS) method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2012년도 춘계학술대회 논문집
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• pp.935-939
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• 2012

3D vibration measurement is achieved using one laser scanning vibrometer(LSV) and Laser scanner(LS) by moving the LSV to three arbitrarily locations from the principle that vibration analysis based on the frequency domain is independent of the vibration signal based on time domain. The proposed system has the same effect as using three sets of LSVs. It has an advantage of reducing equipment costs. Analytical approach of obtaining in-plane and out-of-plane vibration of surface is introduced using geometrical relations between three LSV coordinates and vibration measured at three different locations.

• Proceedings of the KIEE Conference
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• 대한전기학회 2008년도 추계학술대회 논문집 전기기기 및 에너지변환시스템부문
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• pp.111-113
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• 2008

본 논문에서는 복합형 하이브리드 굴삭기의 전력 변환 장치의 구조 및 제어 방법을 제안한다. 제안된 전력 변환 장치는 엔진 다이나모 장치를 이용하여 그 타당성을 입증하였으며, 제한된 실험 환경 내에서도 기존의 유압식 굴삭기와 비교하였을 때, 약 8% 정도의 연비 향상의 효쏙를 얻을 수 있었다. 현재 실제 굴삭기에 장착하여 성능과 연비 측정을 위한 실험이 진행 중이다.

• Journal of the Korean Vacuum Society
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• 제1권1호
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• pp.50-59
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• 1992

By means of X-ray photoelectron spectroscopy(XPS), the initial stages of the oxidation of the cleaved CdTe (110) surface and the sputtered CdTe surface with oxygen exposure are invetigated. From the analyses of the spectra of Te 3dsn, Cd 3d5/2, 0 ls and Cd MNN Auger lines, it is shown that two oxygen atoms bond to one Te atom at the initial stages.

• The Transactions of the Korean Institute of Electrical Engineers C
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• 제54권12호
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• pp.585-587
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• 2005

In this paper, We studied two methods to measure optical characteristics of an electrodeless light source using the integrating sphere(diameter 1.5m). One is to use a center measurement method and the other is to use a side measurement method. As a result of analysis, a side measurement methode without auxiliary lamp is almost similar against a center measurement with auxiliary lamp to reduce a measurement of an error for luminous flux, luminous efficacy and spectral distribution etc. Therefore, Sample which cannot measured by reason of big size and heavy weight can be measured by a side measurement method.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 한국소음진동공학회 2001년도 추계학술대회논문집 II
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• pp.766-771
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• 2001

The package used to transport radioactive materials, which is called by cask, must be safe under normal and hypothetical accident conditions. These requirements for the cask design must be verified through test or finite element analysis. Since the cost for FE analysis is less than one for test. the verification by FE analysis is mainly used. But due to the complexity of mechanical behaviors. the results depends on how users apply the codes and it can cause severe errors during analysis. In this paper, finite element analysis is carried out for the 9 meters free drop and the puncture condition of the hypothetical accident conditions using LS-DYNA3D and ABAQUS/Explicit. We have investigated the analyzing technique for the free drop impact test of the cask and found several vulnerable cases to errors. The analyzed results were compared with each other. We have suggested a reliable and relatively simple analysis technique for the drop test of spent nuclear fuel casks.

• Journal of the Korea Institute of Information and Communication Engineering
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• 제20권3호
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• pp.519-526
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• 2016

As marine accidents happen frequently, it is required to establish a marine traffic monitoring system, which is designed to improve the safety and efficiency of navigation in VTS (Vessel Traffic Service). For this aim, recently, X-band marine radar is used for extracting the sea surface information and, it is necessary to retrieve wave information correctly and provide for the safe and efficient movement of vessel traffic within the VTS area. In this paper, three different current estimation algorithms including the classical least-squares (LS) fitting, a modified iterative least-square fitting routine and a normalized scalar product of variable current velocities are compared with buoy data and then, the iterative least-square method is modified to estimate wave information by improving the initial current velocity. Through several simulations with radar signals, it is shown that the proposed method is effective in retrieving the wave information compared to the conventional methods.