• 한국도로학회논문집
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• 제15권6호
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• pp.25-32
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• 2013

PURPOSES : The purpose of this study is to provide the method of how to measure the coefficient of thermal expansion of concrete using temperature compensation principle of electrical resistance strain gauge. METHODS : The gauge factor compensation method and thermal output(temperature-induced apparent strain) correction method of self-temperature compensation gauge were investigated. From the literature review, coefficient of thermal expansion measurement method based on the thermal output differential comparison between reference material(invar) and unknown material(concrete) was suggested. RESULTS : Thermal output is caused by two reasons; first the electrical resistivity of the grid conductor is changed by temperature variation and the second contribution is due to the differential thermal expansion between gauge and the test material. Invar was selected as a reference material and it's coefficient of thermal expansion was measured as $2.12{\times}10^{-6}m/m/^{\circ}C$. by KS M ISO 11359-2. The reliability of the suggested measurement method was evaluated by the thermal output measurement of invar and mild steel. Finally coefficient of thermal expansion of concrete material for pavement was successfully measured as $15.45{\times}10^{-6}m/m/^{\circ}C$. CONCLUSIONS : The coefficient of thermal expansion measurement method using thermal output differential between invar and unknown concrete material was evaluated by theoretical and experimental aspects. Based on the test results, the proposed method is considered to be reasonable to apply for coefficient of thermal expansion measurement.

• 비파괴검사학회지
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• 제10권1호
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• pp.65-72
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• 1990

Comparison of acoustic emission, ultrasonic testing and crack gauge in 3-point bending testing have been studied. As the results, COD is indirectly assumed by strain gauge rate and grid pitch width when crack gauge grid is out. Acoustic emission is qualitatively able to measure crack growth by total count but ultrasonic testing has a difficulty in measuring it because of echo height fluctuation according to the change and pressure of UT. probe.

• 대한기계학회논문집A
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• 제30권5호
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• pp.560-567
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• 2006

The exact load measurements for the mechanical parts of a wind turbine are important step both fur the evaluation of a specific wind turbine design and for a certification process. A common method for a mechanical load measurement is using a strain gauge sensing. Two main problems ought to be answered in order for this method to be applied to the wind turbine project. These are strain gauge calibration and non-contact signal transmission from the strain gauge output to a load monitoring system. This paper suggests reliable solutions fer these two problems. A Bluetooth, a short range wireless data communication technology, is used to solve the second problem. The first one, the strain gauge calibration methodology for a load measurement in a wind turbine application, is fully explained in this paper. Various mechanical loadings for a strain gauge calibration in a wind turbine load measurement are introduced and analyzed. Initial experimental results which are obtained from a 1 kW small size wind turbine are analyzed, and the uncertainty problem in estimating mechanical loads using a calibration matrix is fully covered in this paper.

• Smart Structures and Systems
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• 제21권4호
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• pp.407-420
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• 2018

In structural health monitoring, it is meaningful to comprehensively utilize accelerometers and strain gauges to obtain the modal information of a structure. In this paper, a modal estimation theory is proposed, in which the displacement modes of the locations without accelerometers can be estimated by the strain modes of selected strain gauge measurements. A two-stage sensor placement method, in which strain gauges are placed together with triaxial accelerometers to obtain more structural displacement mode information, is proposed. In stage one, the initial accelerometer locations are determined through the combined use of the modal assurance criterion and the redundancy information. Due to various practical factors, however, accelerometers cannot be placed at some of the initial accelerometer locations; the displacement mode information of these locations are still in need and the locations without accelerometers are defined as estimated locations. In stage two, the displacement modes of the estimated locations are estimated based on the strain modes of the strain gauge locations, and the quality of the estimation is seen as a criterion to guide the selection of the strain gauge locations. Instead of simply placing a strain gauge at the midpoint of each beam element, the influence of different candidate strain gauge positions on the estimation of displacement modes is also studied. Finally, the modal assurance criterion is utilized to evaluate the performance of the obtained multitype sensor placement. A bridge benchmark structure is used for a numerical investigation to demonstrate the effectiveness of the proposed multitype sensor placement method.

• 비파괴검사학회지
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• 제9권2호
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• pp.50-60
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• 1989

The control of resistance of foil strain gauge is accomplished by means of etching technique. Thus, there is an irregularity in metal foil. In order to solve this problem, ion sputter machining method has been used to make strain gauge in this study and the characteristics of this strain gauge are investigated. As the result of this study, it was possible to make a flexible strain gauge which can be used to measure the stress. The strain gauge made by authors shows superior characteristics in creep, O point variance, hysteresis and nonlinearity by surrounding temperature.

• Journal of Dental Anesthesia and Pain Medicine
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• 제24권2호
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• pp.101-108
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• 2024

Background: Administering anesthesia in dentistry can be distressing for patients, especially those with dental fear and anxiety. Needle pain during local anesthesia is a common concern in intraoral procedures. This study aimed to compare pain perception in 4-6-year-old children following intraoral dental injections with 26- and 31-gauge needles. Methods: Fifty healthy children were divided according to age into Group I (N = 25; 4-5 years) and Group II (N = 25; 5-6 years). Each group was further subdivided according to the needle gauge as follows: Group IA (26 gauge), Group IB (31 gauge), Group IIA (26 gauge), and Group IIB (31 gauge). Using a lottery method, the gauge of the needle to be used at the first visit for local anesthesia administration was selected. Children's reactions to pain were evaluated using a Modified Behavioral Pain Scale. Immediately after administration of local anesthesia, pain perception was evaluated using the Faces pain rating scale. In the subsequent visit, another needle gauge was used to administer local anesthesia, and the previously described evaluations were performed. At the third appointment, the child was shown both syringes and asked to choose one of the syringes they preferred, and the choice was noted. Results: When local anesthesia was administered using a 31-gauge needle, pain perception was similar between the two groups. In group II, the children demonstrated significantly higher arm and leg movements (P = 0.001). However, the difference was significant in group I alone (P < 0.001). Conclusion: Irrespective of age, anesthesia with a 31-gauge needle resulted in significantly lower pain perception than anesthesia with a 26-gauge needle.

• 대한원격탐사학회:학술대회논문집
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• 대한원격탐사학회 1998년도 Proceedings of International Symposium on Remote Sensing
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• pp.70-75
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• 1998

The comparison of Topex/Poseidon sea surface heights and Tide Gauge sea levels was studied in the South Indian Ocean after Topex/Poseidon mission of about 3 years (11- 121 cycles) from January 1993 through December 1995. The user's handbook (AVISO) for sea surface height data process was used in this study Topex/Poseidon sea suface heights ($\zeta$$^{T/P}$), satellite data at the point which is very closed to Tide Gauge station, were chosen in the same latitude of Tide Gauge station. These data were re-sampled by a linear interpolation with the interval of about 10 days, and were filtered by the gaussian filter with a 60 day-window. Tide Gauge sea levels ($\zeta$$^{Argos}$, $\zeta$$^{In-situ}$ and $\zeta$$^{Model}$), were also treated with the same method as satellite data. The main conclusions obtained from the root-mean-square and correlation coefficient were as follows: 1) to Produce Tide Gauge sea levels from bottom pressure, in-situ data of METEO-FRANCE showed very good values against to the model data of ECMWF and 2) to compare Topex/Poseidon sea surface heights of Tide Gauge sea levels, the results of the open sea areas were better than those of the coast and island areas.

• 한국습지학회지
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• 제19권1호
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• pp.103-111
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• 2017

본 연구에서는 강우관측소의 고도별 공간분포의 적정성을 평가하기 위한 방안으로 고도별 강우관측소의 최근린지수를 산정하고, 현재 강우관측소 공간분포의 적정성을 평가하였다. 등면적비를 이용하여 고도를 구분하고, 고도마다 다른 지형적인 조건을 고려하기 위하여 주어진 지형조건내에서 가능한 최대 NNI을 최적화 기법의 하나인 화음탐색법을 이용하여 산정하였다. 이와 같이 고도별로 현재 상태 및 최대 NNI를 산정한 후 이 두 값의 차이를 바탕으로 고도별로 강우관측소 분포를 평가하였다. 그 결과 고도가 높아질수록 공간분포가 상대적으로 취약함을 확인하였다. 추후 강우관측망을 신설할 경우 고도별 특성을 반영한다면 보다 효율적인 강우관측망의 구축이 가능할 것으로 판단된다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.317-322
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• 2004

Productivity of shoe industry in Korea is still more excellent then that of China or Vietnam, But manufacturing technology and productive facility are underdevelopment in comparison advanced country. CAD/CAM system development, one of the most important technology, is totally nonexistent. specially, the automatic generation function and the grading function in shoe sole modeling are dependent of the foreign software. The CAD/CAM software only for shoe modeling is very expensive, so that it is going to weaken shoe industry of Korea. Therefore, We developed 3D gauge curve generation method using 2D NURBS curve in shoe sole modeling.

• Korean Journal of Mathematics
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• 제21권2호
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• pp.125-150
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• 2013

The stabilized Gauge-Uzawa method (SGUM), which is a second order projection type algorithm to solve the time-dependent Navier-Stokes equations, has been newly constructed in 2013 Pyo's paper. The accuracy of SGUM has been proved only for time discrete scheme in the same paper, but it is crucial to study for fully discrete scheme, because the numerical errors depend on discretizations for both space and time, and because discrete spaces between velocity and pressure can not be chosen arbitrary. In this paper, we find out properties of the fully discrete SGUM and estimate its errors and stability to solve the evolution Navier-Stokes equations. The main difficulty in this estimation arises from losing some cancellation laws due to failing divergence free condition of the discrete velocity function. This result will be extended to Boussinesq equations in the continuous research (part II) and is essential in the study of part II.