• Journal of the Korean Society for Precision Engineering
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• v.31 no.11
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• pp.999-1006
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• 2014

In this investigation, we explain the sub-sampling technique of white light scanning interferometry (WLSI) to improve the measurement speed. In addition to the previous work using Fourier domain analysis, several methods to extract the height from the correlogram of WLSI are described with the sub-sampling technique. Especially, Fourier-inverse Fourier transformation method adopting sub-sampling technique is proposed and the phase compensation technique is verified with simulation and experiments. The main advantage of sub-sampling is to speed up the measurements of WLSI but the precision such as repeatability is slightly poor. In case of measuring the sample which has high height step or difference, the proposed technique can be widely used to reduce the measurement time.

• The Journal of Korea CHUNA Manual Medicine
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• v.5 no.1
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• pp.243-249
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• 2004

Objectives : This study is to evaluate the effect of flexion-distraction technique by measuring surface EMG in low back pain groups. Methods : 5 low back pain patients' constact time, power, fatigue, recovery of muscle were measured before and after flexion-distraction technique. Results : The asymmetry ratio of surface EMG in low back pain groups were Increased, but decreased after flexion-distraction technique. Conclusions : Surface EMG might be used for evaluating the effect of flexion-distraction technique.

• The Korean Journal of Rheology
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• v.11 no.1
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• pp.57-65
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• 1999

In order to measure yield stress of PIM feedstocks simply and effectively, a yield stress measuring technique was developed by a vane method. The vane method had an advantage that there was no wall-slip, while it had a drawback that it could not measure viscosity change at various shear rates. A Newtonian fluid was tested for the appropriateness of the measuring technique. The end effect of a vane was checked to produce an acceptable error. The torque peak has been considered to be developed at yielding of non-Newtonian fluids with yield stress. However, it was influenced very much by control system of the instrument so that the torque value at the stable region was taken to calculate yield stress. Torque at zero rotational speed was obtained by extrapolating the torque values at various speeds to remove the effect of the rotational drag. As general verification, yield stress of feedstocks made of Tungsten carbide powder with wax-based binder was measured at different temperatures and various powder concentrations.

• The Journal of Advanced Prosthodontics
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• v.12 no.3
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• pp.173-180
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• 2020

PURPOSE. This study compared digital (reference point matching) and replica methods for measuring marginal and internal fit of full coverage restorations. MATERIALS AND METHODS. A maxillary left first molar typodent was fixed on to an aluminum base and prepared to receive all-ceramic full coverage restoration. The model was scanned with an intraoral scanner (CEREC Omnicam, Sirona, York, PA, USA). Twelve crowns were fabricated from lithium disilicate blocks (IPS emax CAD, Ivoclar Vivadent) and then crystalized. Marginal and internal fit of each restoration was measured by two examiners using replica and a new digital three-dimensional technique. Reliability between the two methods and two examiners was assessed by correlation and Cronbach's Alpha coefficient (P<.05). A Bland-Altman assessment for agreement was used to compare the two methods. RESULTS. Bland-Altman assessment showed that the mean of difference for marginal, absolute marginal, and axial gap was respectively -1.04 ㎛, -41.9 ㎛, and -29.53 ㎛ with limit of agreement (LOA) between -37.26 to 35.18 ㎛ for marginal, -105.85 to 22.05 ㎛ for absolute marginal and -80.52 to 22.02 ㎛ for axial gap. Positive correlation for repeatability (P<.05) in determining marginal and internal gaps by the two examiners in both techniques was revealed. Reliability of both techniques in all sites of measurements was at least good (0.8 ≤ α < 0.9). CONCLUSION. Both measuring techniques appeared highly reliable for evaluating fit of fixed dental restorations, while reference point matching provided higher values in axial and absolute marginal gap assessment.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.509-516
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• 2004

The measurement of abnormal change of temperature(temperature anomaly) will help determine the safety of various engineering constructions, as the measurement in body often used to diagnose one's health. Temperature anomaly can be occurred in leakage or seepage of water flow in rocks, and in ground water table etc. Grouting materials injected in fractured rocks generate heat during hardening process. The degree of temperature change is associated directly with heat flow characteristics, that is, thermal conductivity, specific heat capacity. density of the surrounding rocks and can afford to assess the grouting efficiency. However, in practice, the use of traditional temperature measuring technique composed of only one single thermal sensor has been fundamentally limited to acquire thermal data sufficient to use for that, partly due to the time-consuming measuring work, partly due to the non-consecutive quality of data. Thus, in this paper, a new concept of temperature measuring technique, what we call, thermal line sensor technique is introduced. In this, the sensors with an accuracy of $0.02^{\circ}$ are inserted at regular intervals in one line cable and addressed by a control device, which enables to fundamentally enhance the capability of data acquisition in time and space. This new technology has been demonstrated on diverse field model experiments. The results were simply meant to be illustrative of a potential to be used for various kinds of temperature measurements encountered in grouting and leakage problems.

• Journal of the Microelectronics and Packaging Society
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• v.24 no.1
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• pp.57-65
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• 2017

The electronic components in mobile device are composed of electronic chips and various other materials. These components become extremely thin and the constituent materials have different coefficient of thermal expansion, so that considerable warpages occurs easily due to temperature change or external load. Shadow $moir{\acute{e}}$ is non-contact, whole field technique for measuring out-of-plane displacement, but the measurement sensitivity is not less than $50{\mu}m/fringe$, which is not suitable for measuring the warpage of the electronic components. In this paper, we implemented a measurement method with enhanced sensitivity of $25{\mu}m/fringe$ by investigating and optimizing various experimental conditions of the shadow $moir{\acute{e}}$. In addition, four $moir{\acute{e}}$ fringe patterns recorded by the phase shift are processes to obtain a $moir{\acute{e}}$ fringe patterns with a sensitivity four times higher. The measurement technique is applied to small electronic components of a smart phone for measuring warpage with a high sensitivity of $5{\mu}m/fringe$ at room temperature and at the temperature of $100^{\circ}C$.

• Proceedings of the Korean Society for Emotion and Sensibility Conference
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• 1998.11a
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• pp.172-177
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• 1998

For making high-functional illumination environment and pleasantness to human beings, it is needed to analyze optical characteristics from lightsource as well as to analyze and examine emotional characteristics which respond to optical characteristics systematically. Also, it is Possible to classify lightsource according to function and use based on optical and emotional characteristics systematically and these results can be applied to practical data for professional illumination design field. The aim of this study is to develop technique for evaluating sensibility as well as to accumulate sensibility database through measuring and evaluating emotional reaction to optical characteristics from lightsource. Final aim of this study is to develop simulation and evaluation technique for interior illumination environment, the outline of this paper : 1) operating simulator for various illumination environment 2) developing evaluation methodology for evaluating illumination environment 3) preparing sensibility index through evaluation and analysis The process of this study is as follows. 1) Developing optical evaluation item of lightsource 2) Developing emotional evaluation item of lightsource 3). Analyzing, correlation between optical evaluation item and emotional eveluation item 4) Classifying and selecting object for evaluation 5) Optical measuring and evaluating for lightsource 6) Operating Simulator for illumination environment 7) Emontional measuring and evaluating lightsource and color 8) Developing estimative formula and sensibility index of emotional reaction The results of this study are as follows. 1. Simulator is operated for various illumination environment, and it is proved to be applicable to actual environment. 2. Evaluation and Analysis Techniques is developed for emotional measurement about illumination environment. 3. Estimative formula and sensibility index are prepared, which can estimate the characteristic of lightsource and emotional reaction to interior color

• Journal of the Korean Society for Nondestructive Testing
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• v.29 no.2
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• pp.104-107
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• 2009

It was verified that the effect of the distance between current input point and output point on direct current potential drop(DCPD) in the material with two-dimensional surface notch. If the distance between potential drop measuring points was fixed at a certain distance, the potential drop was decreased with increasing the distance between current input and output points. Hence it is the effect way to increase sensitivity in DCPD that the current input and output points should be located near the potential measuring points. DCPD was a useful method for surface crack sizing because the potential drop was proportional to the length of notch. When the current input and output points are located near the potential measuring points, even small length crack can be measured by DCPD technique.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.13 no.11
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• pp.5587-5594
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• 2012

Determination of the soil-water characteristic curve is one of the most important things to solve geotechnical engineering problems. Expecially, convenient and reliable method to measure the soil-water characteristic curve during drying and wetting cycles is required with lower labor input, more independence from operator experience, and shorter testing time than other available methods. Many measurement methods including the flow pump system have been developed to characterize the soil-water characteristic curve for the several decades. This study measured the soil-water characteristic curve during drying and wetting cycles using a suction control technique with the flow pump system. Two test materials were used for determination of the soil-water characteristic curve, and it is concluded that suction control technique is suitable for determination of the soil-water characteristic curve and characterization of the hydraulic hysteresis with varying test conditions. Especially, the suction control technique can reduce error of measurement and save time in measuring the soil-water characteristic curve due to automated system and high degree of precision.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.33 no.2
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• pp.128-136
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• 2011

Purpose: Errors in orthognathic model surgery occur during the planning, measuring and/or moving of the models. However, there has been little effort to find ways to reduce these errors. In this study, we introduce a new orthognathic model surgery technique (Yonsei method) which adopts the tooth point as the reference and the occlusal index as a moving vehicle for the model. Methods: The technique consists mainly of: 1) measuring the three-dimensional lengths of model points, 2) fabricating and moving the occlusal index and 3) verifying the movement. Then we compared the accuracy of the Yonsei method to conventional methods, with special reference made to influencing factors. Results: Errors for the Yonsei method with the occlusal index were reduced to the range of 0.61~1.04 mm in three-dimension, providing a more accurate model surgery technique than conventional methods which have errors ranging from 0.77~3.11 mm. Conclusion: It provided us a more accurate model surgery technique based on the reference points onto the teeth and the use of occlusal index.