Earticle

Measurement is used for evaluation of product or process exactly. If it couldn't measured correctly, Quality-cost must be raised and it would be hard to improve product quality. So, this study suggests improvement guide line for the multilateral problems of measuring instrument operation based on the investigation of 157 small and medium-sized enterprises in February, 2008. To use inspection gig correctly, man who treat it must be accustomed with the structure, the performance, the method. The inspection gig is selected properly for the measurement goal. If not, results couldn't be correctly or wasted time, efforts, and costs. When selecting a inspection gig, the locating, the clamping, and the efficiency must be considered.

Measurement is a essential part in all kinds of industry, especially in manufacturing. But until now, measurement hasn't been located to the core of manufacturing in domestic. This study suggests improvement guide line for the multilateral problems of measuring instrument operation based on the investigation of small and medium-sized enterprises. To use measuring instrument correctly, man who treat it must be accustomed with the structure, the performance, the method. The measuring instrument must be corrected periodically. The correcting-schedule is established with environments with considering accuracy, stability, purpose, condition, and frequency.

3차원 측정기는 물체의 표면 위치를 검출하는 기능을 가진 센서가 3차원 공간을 움직이면서 측정점을 좌 표를 검출하고 컴퓨터를 통해 그 데이터를 처리함으로써 크기나 위치, 방향 등을 측정하는 측정기이다.[1] 복잡한 형 상의 부품에 대한 기하학적 특성을 공간좌표 상에서 쉽게 측정할 수 있도록 제작된 측정기가 3차원 측정기 이며, 역설계, 제품의 품질관리, 제품의 신뢰도확보, 제품평가를 위해 3차원 측정기의 활용도가 중시되고 있다. 하지만 3 차원 측정기의 활용에 측정 정밀도 및 신뢰성 미흡은 3차원 측정기의 활용을 어렵게 한다. 3차원 좌표측정기의 측 정 정밀도는 실제 사용자의 숙련도에 의존 할 수 있으나 더 큰 원인은 측정을 위한 측정조건이라고 할 수 있다. 특히 온도는 3차원 좌표측정기의 측정에 중요한 조건이며, 본 연구에서는 고온 측정물이 측정오차에 미치는 영향 에 대해 연구하였다. 그 결과 측정값의 오차 변형률 및 불확도가 30～50℃ 사이에서는 불확도가 크게 나타났다.

Three dimensional coordinate measuring machine is a measuring instrument that measures size, location, direction with the sensor that has detection function of location of object on the surface by moving three dimensional space as detecting the coordinates of measurement point and running the data through computers. Three dimensional coordinate measuring machine was designed to measure geometrical characteristics of component with a complex shape on spatial coordinates, so the availability of three dimension measuring instrument is getting more important for reverse engineering, quality control of the product, ensuring reliability of product, manufacture evaluation. But measurement of precision of 3dimension measuring instrument and insufficiency of reliability make the use of 3 dimension measuring instrument harder. The measurement precision of three dimensional coordinate measuring machine can rely on the skills of the actual user, but the bigger cause is the measuring condition for measurement. Especially, temperature is a crucial condition and in this study, I did research on the effect that high temperature measure object affects measurement errors. As a result, The error strain and uncertainty of the measured value were large between 30 and 50 °C. So it seems to be very important to keep the condition at a standard temperature when we measure these kinds of materials. The result of this study is to minimize measurement errors on three dimensional coordinate measuring machine. and I expect it would contribute to its reliability improvement.

The CMM is the most widely used measuring device in the field. The three-dimensional measurement method is divided into a method of scanning the shape of a product and a touch method. In this study, the accuracy of the dimension and shape of each measurement point touch method was analyzed based on the measured value with the touch method CMM using the inner and outer diameter measurement specimens. Through the experimental results, it was possible to obtain the closest value to the true value at more than 30 measurement points.

We develop methods for propagating and analyzing EPCI(Extended Process Capability Index) by using the error type that classifies into accuracy and precision. EPCI developed in this study can be applied to the three combined processes that consist of production, measurement and calibration. Little calibration work discusses while a great deal has been studied about SPC(Statistical Process Contol) and MSA(Measurement System Analysis). EPCI can be decomposed into three indexes such as PPCI(Production Process Capability Index), PPPI(Production Process Performance Index), MPCI(Measurement PCD, and CPCI(Calibration PCI). These indexs based on the type of error classification can be used with various statistical techniques and principles such as SPC control charts, ANOVA(Analysis of Variance), MSA Gage R&R, Additivity-of-Variance, and RSSM(Root Sum of Square Method). As the method proposed is simple, any engineer in charge of SPC. MSA and calibration can use efficientily in industries. Numerical examples are presentsed. We recommed that the indexes can be used in conjunction with evaluation criteria.

In this study, measurement errors of the X and Y axes were verified by using an 80-100 mm gauge block, an NPL type angle measuring device, and a spelling on a contact-type 3D measuring device surface plate. In addition, the measurement specimen was repeatedly measured 10 times at 10° intervals from 0° to 40° to confirm the average value and standard deviation. After confirming the statistical test value (P) through ANOVA analysis of the statistical program, the correlation between angle change and error was confirmed.

In this study, using a 100mm gauge block in a contact-type three-dimensional measuring machine surface plate, an NPL-type angle measurement, and a steel ruler, the specimen was measured at 0°, 5°, 10°, 20°, 30°, and 40° along the X and Y axes. After setting the measurement conditions, the average value and standard deviation were confirmed by repeating measurements for each yield 10 times. After checking the statistical test value (P) through ANOVA, the correlation between the angle change and the error was checked.

탄광, 지하실, 지하창고 등 위험한 지역에서 일하는 일군들의 움직임을 비롯한 위치 측정은 안전을 위해 반드시 필요한 기술이다. 위험하고 제한된 환경에서의 USN의 위치 측정 기법들은 다양하게 존재한다. 위치 측정 기법 중에 삼각측량법은 간단하기 때문에 여러 분야에서 많이 적용되고 있다. 하지만 측정기구와 전파 장애 및 물리적 장애로 인해 오차가 발생하여 정확한 위치를 파악하기 어렵다. 본 논문에서는 4개의 Anchor와 움직이는 노드 사이의 거리 정보를 다양하게 활용하여 재계산하여 기존 삼각측량법으로 얻은 위치보다 오차범위를 줄일 수 있는 방법을 제안한다. 또한 제안 기법을 통해 거리 측정하여 움직이는 노드의 위치 즉, 예측점을 계산하였을 때는 기존 삼각측량법보다 계산의 오버로드가 발생하지만 수학적으로 위치측정 오차 범위 계산 시 41%가 향상되었다.

The location measurement technique of moving worker in dangerous areas, is necessary for safety in the mines, basements, warehouses, etc. There are various measurement techniques about moving node of position in a restricted environment. Trigonometric Method, one of measurement techniques, is commonly used because of its easiness. However, errors occur frequently when measuring distance and position due to radio interference and physical disability with measuring instruments. This paper proposed a method which is more accurate and shows reduced margin of error than existing trigonometric method by recalculating distance between Anchor and moving node with various measuring instruments. By adding Anchor when calculating distance and position of moving node's estimated point, suggested technique obtains at least 41% efficiency compared to existing method.

The results of the measurements using an optical surface roughness meter are shown according to the angle changes of 0, 0.5, 1, 1.5, 2, and 3°. Through the experiment, it can be seen that the measurement value is 3.140 at 0°, 3.148 at 0.5°, 3.140 at 1°, 3.151 at 1.5°, 5.078 at 2°, and 4.790 at 3° setting. In addition, the test statistic (P) value is 0.000, which is smaller than the significance level of 0.005, so it was confirmed through the experiment that a measurement error occurs according to the angle change when measuring the surface roughness.

Location-Based Service(LBS) is a service that provides a variety of convenience in life using location information that can be obtained by mobile communication network or satellite signal. In order to provide LBS precisely and efficiently, we need the location determination technology, platform technology and server technology. In this study, we studied on how we can reduce the error on location determination of objects such people and things. Fingerprint location determination method was applied to this study because it can be used at current wireless communication infrastructure and less influenced by a variety of noisy environment than other location determination methods. We converted the probability value to logarithmic scale value because using the sum of k probability values is not suitable to be applied to weight determination. In order to confirm the performance of suggested method, we developed location determination test program with Visual Basic 6.0 and performed the test. According to indoor and outdoor test results, the suggested stochastic method reduced the distance error by 17%, 18% and 9% respectively at indoor environment and 25%, 11% and 4% at outdoor environment compared with deterministic NN, kNN and kWNN fingerprint methods.

Failure to comply with the performance test requirements for the centrifugal pumps at power plants often results in performance dissatisfaction as a result of field tests. This study proposed a method of reducing the uncertainty of the field test results by evaluating the systematic error in the measurement system caused by failure to follow the test requirements using the computational fluid dynamics(CFD) technique. As a result of the evaluation of the systematic error and reflecting it in the performance test data, it was confirmed that the error occurred at a constant rate with respect to the flowrate and that the pump, which showed a difference in performance actually had the same performance.

레이다는 표적에 대한 정보를 도출하기 위해 전파를 송신하고, 표적으로부터 반사된 신호를 수신하여 정보를 도출한다. 일반적인 레이다의 경우, 전파의 송수신 경로가 직선으로 가정하여 표적의 정보를 도출한다. 그러나 대기가 불안정한 환경에서는 대기 굴절률의 차이에 의한 전파의 굴절 현상이 발생한다. 전파의 굴절 현상에 의해 직선으로 가정 하였던 전파의 송수신 경로가 휘게 되고, 이를 기반으로 표적 정보를 추정할 때 표적 정보에 오차가 발생하게 된다. 특히 장거리 레이다의 경우 대기 굴절률에 의한 오차의 정도가 심하여 대기 굴절률에 의한 보정을 필요로 한다. 본 논문에서 는, 표적 정보를 추정하는 과정에서 대기 굴절률에 의한 전파 굴절 현상이 오차를 발생시키는 이유를 알아보고, 하나의 시나리오를 가정하여 표적의 거리, 각도, 속도(도플러)의 측면에서 오차를 분석하였다.

Radar detects target information by receiving signals that are reflected from target. Conventional radar assumes the tramsmitted and reception paths of signal are straight to derive target information. However, when atmospheric conditions are unstable, variation of atmospheric refractivity causes the transmitted/received signal paths to curve due to refraction. This curvature introduces errors in estimation of target information. Case of long range radar, errors due to atmospheric refractivity significantly affect radar performance so that compensation of atmospheric refractivity is needed. In this paper, we investigated how refracted path affects to radar performance and the errors induced by atmospheric refractivity in range, angle, velocity(doppler).

Purpose: To compare refractive error measured by hand-held wavefront aberrometers with postcycloplegic autorefraction (AR) and cycloplegic refraction (CR). Methods: The medical records of patients who received refractive measurements using the wavefront aberrometer, postcycloplegic AR, and CR between January 2014 and January 2016 were retrospectively analyzed. The mean differences, 95% confidence intervals, and limits of agreement (LOA) were calculated for the refractive vector components (M, J0, and J45). Results: Fifty-one patients (9.0 ± 5.5 years, male 41.2%) were enrolled in this study, and only the right eye of each was included. Refractive errors ranged from -9.25 to +7.25 diopters (D) for spherical equivalent (median, 0.75 D). The M component was not significantly different among the three methods (p = 0.080). However, the J0 vector component was significantly different (p < 0.001). After post hoc analysis, the wavefront aberrometer obtained more positive values for J0 compared to the other methods. The J45 component was not significantly different among the three methods (p = 0.143). The mean difference between the wavefront aberrometer and postcycloplegic AR was -0.115 D (LOA, -1.578 to 1.348 D) for M, 0.239 D (LOA, -0.371 to 0.850 D) for J0, and -0.015 D (LOA, -0.768 to 0.738 D) for J45. The mean difference between the wavefront aberrometer and CR was -0.220 D (LOA, -1.790 to 1.350 D) for M, 0.300 D (LOA, -0.526 to 1.127 D) for J0, and -0.079 D (-0.662 to 0.504 D) for J45. Conclusions: The wavefront aberrometer showed good agreement with postcycloplegic AR and CR in spherical equivalents, but tended to produce slightly myopic results. The wavefront aberrometer also overestimated with-the-rule astigmatism. Therefore, we recommend that the device be used for estimations of refractive error, which may be useful for patients who have postural difficulties, live in undeveloped countries, or are bedridden.

The contour method relies on deformations that occur when a residually stressed component is cut along a plane. The method is based on the elastic superposition principle. When plasticity is involved in the relaxation process, stress error in the resulting measurement of residual stress would be caused. During the cutting the specimen is constrained at a location along the cut so that deformations are restrained as much as possible during cutting. With proper selection of the constraining location the plasticity effect can also be minimized. Typical patterns of longitudinal welding residual stress state were taken to assess the plasticity effect along with constraining locations.

Metrology tools with the ability to measure spindle motion error on the order of a nanometer are required due to recent advances in nanotechnology. We propose a direct measurement method for the radial motion error of a precision spindle using a regular crystalline lattice and a scanning tunneling microscope (STM). A highly oriented pyrolytic graphite (HOPG) crystal combined with an STM is used as a two-dimensional reference scale. The measurement principle and the preliminary experimental results are discussed in this article. The preliminary experimental results demonstrated that the proposed method has the capability to incorporate a two-dimensional encoder to measure the spindle motion error.