• 한국세라믹학회지
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• 제31권8호
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• pp.902-910
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• 1994

Residual stress measurements were made for cylindrical glass rods to compare experimental results with the calculated values obtained by Instant Freezing Model. According to the photoelastic measurements, the stress ratio of surface compression and center tension was increased from 1.4 to 2.0 as the heat-treatment temperature was lowered, the fictitious forzen temperature was found to be closer to the heat-treatment temperature and the fictitious coefficient was increased.

• 한국대기환경학회지
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• 제20권2호
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• pp.237-249
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• 2004

With the increasing concern over the air quality degradation, there are growing demands to accurately and precisely measure air quality. In this article, the general principles and approaches were described to help aid proper evaluation of air quality. In order to introduce the basic approaches for conducting field/laboratory experiments and for interpreting experimental data sets, we explained all the common methodologies involved and provided some insights into the desirable protocols for air quality measurements.

• Wind and Structures
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• 제4권2호
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• pp.101-118
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• 2001

This paper reports the field measurements concerning pressure equalization of rainscreen facades carried out at the Technical University of Eindhoven (TUE) in the Netherlands. The field facility including the details of test panel, meteorological tower, instrumentation, data collection and analysis is presented. Results of investigations into cavity response for various leakage and venting configurations are discussed. Frequency domain techniques have been utilized to show the influence of wind as well as facade characteristics on the pressure equalization performance. Further, this paper presents an early attempt to synthesize the experimental results into existing building codes.

• Korea-Australia Rheology Journal
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• 제14권3호
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• pp.93-105
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• 2002

Experimental methods for making quantitative measurements of velocity fields in non-Newtonian fluids are reviewed. Techniques based on light scattering spectroscopy - laser Doppler velocimetry and homodyne light scattering spectroscopy, techniques based on imaging the displacement of markers - including particle image velocimetry and molecular tagging velocimetry, and techniques based on nuclear magnetic resonance imaging are discussed. The special advantages and disadvantages of each method are summarized, and their applications to non-Newtonian flows are briefly reviewed. Example data from each technique are also included.

• Korea-Australia Rheology Journal
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• 제14권2호
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• pp.87-90
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• 2002

The measurement of the storage and loss moduli (G' and G" respectively) of materials as functions of frequency is now commonplace and is of wide utility. Yet il is not easy to trace the history of such measurements. and so this article discusses the genesis of this important experimental technique. We find that the technique grew out of a parallel technique for dielectric measurements (ca. 1900) and was developed in the mid-1930s by Philippoff and others. Important breakthroughs due to digital circuitry have occurred only in the last 20 years or so.r so.

• Korea-Australia Rheology Journal
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• 제19권3호
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• pp.117-123
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• 2007

There has been considerable interest in recent years in field-responsive suspensions, which are of some importance in industry in many different applications. The microstructure of these materials is a significant issue which can be probed by rheological measurements. In this study, measurements were made of a magnetorheological fluid (MRF) under steady and oscillatory shear flow, with and without a magnetic field. Mathematical inversion was used to derive the relaxation time spectrum of the MRF from oscillatory shear data. Experimental evidence is presented of the gel-like properties of this MRF.

• 한국자기공명학회논문지
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• 제16권2호
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• pp.122-132
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• 2012

The effects of the sample viscosity and volume on the convective flows induced by temperature gradient in PGSE-NMR self-diffusion measurements at high temperature have been investigated. The experimental results showed that the viscosity of the liquid sample strongly affects the magnitude of the convective flows as well as the diffusion coefficient itself. It was also found that the convective flows increase as the sample volume increase.

• International Journal of Fluid Machinery and Systems
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• 제10권2호
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• pp.164-175
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• 2017

Francis turbines are often operated over a wide load range due to high flexibility in electricity demand and penetration of other renewable energies. This has raised significant concerns about the existing designing criteria. Hydraulic turbines are not designed to withstand large dynamic pressure loadings on the stationary and rotating parts during such conditions. Previous investigations on transient operating conditions of turbine were mainly focused on the pressure fluctuations due to the rotor-stator interaction. This study characterizes the synchronous and asynchronous pressure and velocity fluctuations due to rotor-stator interaction and rotating vortex rope during load variation, i.e. best efficiency point to part load and vice versa. The measurements were performed on the Francis-99 test case. The repeatability of the measurements was estimated by providing similar movement to guide vanes twenty times for both load rejection and load acceptance operations. Synchronized two dimensional particle image velocimetry and pressure measurements were performed to investigate the dominant frequencies of fluctuations, vortex rope formation, and modes (rotating and plunging) of the rotating vortex rope. The time of appearance and disappearance of rotating and plunging modes of vortex rope was investigated simultaneously in the pressure and velocity data. The asynchronous mode was observed to dominate over the synchronous mode in both velocity and pressure measurements.

• 한국정보통신학회논문지
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• 제14권11호
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• pp.2555-2562
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• 2010

본 논문에서는 수작업을 최소화하면서 조위 기록지로부터 조위 기록 그래프를 추출하는 방법을 제안한다. 사용자가 그래프 상의 하나의 픽셀을 선택하면, 선택된 픽셀과 나머지 픽셀들과의 LAB 색상 공간상에서의 관계를 이용해 자동으로 대부분의 배경 픽셀들을 결정한다. 배경 픽셀들이 결정되면, 각 세로줄에서 그래프 영역으로 판단되는 한개의 픽셀을 추출하고, 이 픽셀을 시작 위치로 하여 나머지 그래프 영역을 추출한다. 실험 결과는 다양한 종류의 조위 기록지로부터 최소한의 수작업만으로 조위 기록 그래프 영역을 검출할 수 있음을 보여준다.

• Smart Structures and Systems
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• 제12권6호
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• pp.619-640
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• 2013

It is highly desirable to explore efficient algorithms for detecting structural damage of large size structural systems with limited input and output measurements. In this paper, a new structural damage detection algorithm based on substructure approach is proposed for large size structural systems with limited input and output measurements. Inter-connection effect between adjacent substructures is treated as 'additional unknown inputs' to substructures. Extended state vector of each substructure and its unknown excitations are estimated by sequential extended Kalman estimator and least-squares estimation, respectively. It is shown that the 'additional unknown inputs' can be estimated by the algorithm without the measurements on the substructure interface DOFs, which is superior to previous substructural identification approaches. Also, structural parameters and unknown excitation are estimated in a sequential manner, which simplifies the identification problem compared with other existing work. Structural damage can be detected from the degradation of the identified substructural element stiffness values. The performances of the proposed algorithm are demonstrated by several numerical examples and a lab experiment. Measurement noise effect is considered. Both the simulation results and experimental data validate that the proposed algorithm is viable for structural damage detection of large size structural systems with limited input and output measurements.