• Journal of Construction Engineering and Project Management
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• 제2권2호
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• pp.45-52
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• 2012

This study introduces a methodology to evaluate different types of non-nuclear technologies to see how they are competitive to the nuclear technology for quality control (QC) and quality assurance (QA) in soil condition measurement for highway pavement construction. The non-nuclear methods including the Electrical Density Gauge (EDG) and the Light Weight Deflectometer (LWD) were tested for their performance against a nuclear gauge, and traditional methods were used as baselines. An innovative way of comparing a deflection gauge to a density gauge was introduced. Results showed that the nuclear gauge generally outperformed the non-nuclear gauge in accuracies of soil density and moisture content measurements. Finally, a framework was developed as a guideline for evaluating various types of non-nuclear soil gauges. From other perspectives rather than accuracy, it was concluded that the non-nuclear gauges would be better alternative to the nuclear gauge when the followings are considered: (1) greater life-cycle cost savings; (2) elimination of intense federal regulations and safety/security concerns; and (3) elimination of licensing and intense training.

• Nuclear Engineering and Technology
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• 제1권2호
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• pp.103-106
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• 1969

gauge독립한 새로운 unitary변환을 도입함으로서 진동하고 있는 전장안에서의 spin 1/2 가전입자의 운동을 기술하는데 적합한 Dirac 방정식의 표시가 도출되고 있다. 이 새로운 표시에 있어서 potentials를 포함하지 않은 유효 Hamiltonian은 그 비상대론적 근거에서 새로운 특성을 나타내는 사실을 보여주고 있다.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1994년도 가을 학술발표회 논문집
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• pp.71-76
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• 1994

Recently, constructions of huge reinforced concrete structures such as nuclear power stations have been increased. When massive concrete is placed, cracking due to the hydration heat of cement is recognized as a major problem. The development of thermal stress is influenced by the structure shape and the constraint conditions, and cracks usually occure from tensile stresses which developed due to temperature drop. In this study a protocol specimen is made to examine the distribution of temperature and thermal stress of reaction wall of Daewoo Institute Construction Technology. The size of the specimen is made by considering minimum size of real structure. In this study, concrete strain gauge, concrete stress gauge, concrete non-stress gauge, and thermocouples, are instrumented to measure thermal stress in massive concrete structure. A new measuring technique is proposed to calculate thermal stress.

• 한국도로학회논문집
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• 제17권1호
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• pp.51-58
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• 2015

PURPOSES : The objective of this study is to compare the densities of asphalt pavements measured both in the field and in the laboratory, and also to evaluate the applicability of field density measuring equipment, such as the pavement quality indicator (PQI), by using statistical analysis. METHODS : For the statistical analysis of the density measured from asphalt pavement, student t-tests and a coefficient of correlation are investigated. In order to compare the measured densities, two test sections are prepared, with a base layer and an intermediate layer constructed. Each test section consists of 9 smaller sections. During construction, the field densities are measured for both layers (base and intermediate) in each section. Core samples are extracted from similar regions in each section, and moved to the laboratory for density measurements. All the measured densities from both the field and laboratory observations are analyzed using the selected statistical analysis methods. RESULTS AND CONCLUSION : Based on an analysis of measured densities, analysis using a correlation coefficient is found to be more accurate than analysis using a student t-test. The correlation coefficient (R) between the field density and the core density is found to be very low with a confidence interval less than 0.5. This may be the result of inappropriate calibration of the measuring equipment. Additionally, the correlation coefficient for the base layer is higher than for the intermediate layer. Finally, we observe that prior to using the density measuring equipment in the field, a calibration process should be performed to ensure the reliability of measured field densities.

• 방사성폐기물학회지
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• 제19권2호
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• pp.197-204
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• 2021

In this study, the well-known non-destructive acoustic emission (AE) and electrical resistivity methods were employed to predict quantitative damage in the silo structure of the Wolsong Low and Intermediate Level Radioactive Waste Disposal Center (WLDC), Gyeongju, South Korea. Brazilian tensile test was conducted with a fully saturated specimen with a composition identical to that of the WLDC silo concrete. Bi-axial strain gauges, AE sensors, and electrodes were attached to the surface of the specimen to monitor changes. Both the AE hit and electrical resistance values helped in the anticipation of imminent specimen failure, which was further confirmed using a strain gauge. The quantitative damage (or damage variable) was defined according to the AE hits and electrical resistance and analyzed with stress ratio variations. Approximately 75% of the damage occurred when the stress ratio exceeded 0.5. Quantitative damage from AE hits and electrical resistance showed a good correlation (R = 0.988, RMSE = 0.044). This implies that AE and electrical resistivity can be complementarily used for damage assessment of the structure. In future, damage to dry and heated specimens will be examined using AE hits and electrical resistance, and the results will be compared with those from this study.

• 한국정밀공학회지
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• 제12권10호
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• pp.40-49
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• 1995

This paper presents the performance and problems in analysis method and testing system of Electronic Speckle Pattern Interferometry (ESPI) method, in measuring two - dimensional in-plane displacement. The anyalysis result of measurement by ESPE is quite comparable to that tof measurement by strain gauge method. This implies that the method of ESPE is a very effective tool in non-contact two-dimensional in-plane strain analysis. But there is a controversal point, measurment error. This error is discussed to be affected not by ESPE method itself, but by its analysis scheme of the interference fringe, where the first-order interpolation has been applied to the points of strain measured. In this case, it is turned out that the more errors would be occurred in the large interval of fringe. And so this paper describes a computer method for drawing when the height is available only for some arbitrary collection of points. The method is based on a distance-weighted, last- squares approximation technique with the weight varying with the distance of the data points.