• 한국전기전자재료학회논문지
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• 제21권9호
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• pp.868-871
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• 2008

We propose an optical-based measuring instrument of catenary system in electric railway. This system was made to utilize line scan camera as inspecting system to measure the stagger and height of overhead contact wire in railway and composed with optical type source and FPGA-based image acquisition system with PCI slot. Vision acquisition software has been used for the application to programming interface for image acquisition, display, and storage with a frequency of sampling. To check the validity of our approach for the intended application, we monitored height and stagger in the overhead wire of a high-speed catenary system in Korea. The proposed optical-based measuring instrument to measure the contact wire geometry such as the hight and stagger shows promising on-field applications for online condition motoring. We expect that a new generation of real-time instruments with demanding various conditions motoring requirement in railway can be easily integrated into optical-based measuring instrument system.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2005년도 춘계학술대회 논문집
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• pp.1543-1546
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• 2005

This paper presents a method to measure a large surface shape using atomic force microscopy, which has been used mostly for measuring over very tiny surfaces. Experiments are performed to measure a step height and a slope of a test sample. The proposed method is rigorously compared with the coordinate measuring machine. The repetition accuracy and the effects of the set point are also studied. The experimental results show that the proposed method is reliable and should be effective to measure both the nano-accuracy surface profile as well as the micro-accuracy global shape of a macro/micro parts using atomic force microscope.

• Current Optics and Photonics
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• 제8권2호
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• pp.170-182
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• 2024

The dimensional accuracy and consistency of a dual oil circuit centrifugal fuel nozzle are important for fuel distribution and combustion efficiency in an engine combustion chamber. A point cloud measurement method was proposed to solve the geometric accuracy detection problem for the fuel nozzle. An improved variance focus measure operator was used to extract the depth point cloud. Compared with other traditional sharpness evaluation functions, the improved operator can generate the best evaluation curve, and has the least noise and the shortest calculation time. The experimental results of point cloud slicing measurement show that the best window size is 24 × 24 pixels. In the height measurement experiment of the standard sample block, the relative error is 2.32%, and in the fuel nozzle cone angle measurement experiment, the relative error is 2.46%, which can meet the high precision requirements of a dual oil circuit centrifugal fuel nozzle.

• 태양에너지
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• 제5권2호
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• pp.11-19
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• 1985

In this paper, the interface stability not to occur mixing and entrainment between the adjacent layers has been studied in the case of the selective withdrawal of a stratum and the injection in stratified fluid formed by the density difference in a small solar pond. There are stability parameter, Richardson number, Rayleigh number and Froude number as the parameters governing stability in order to measure the interface stability on the stratified fluid. The model which could measure the interface stability on the stratified fluid was the small solar pond composed by 1 meters wide, 2 meters high, and 5 meters long. In order to measure the interface stability on the stratified fluid at the inlet port, the middle section and the outlet port, Richardson number, Rayleigh number, and Froude number involved in the parameters governing the stability were calculated by means of the data resulted from the test of the study on hydrodynamic stability between the convective and nonconvective layers in that solar pond. Richardson number written by the ratio of inertia force to buoyancy force can be used in order to measure the stability on the stratified fluid related to the buoyancy force generated from the injection of fluid. Rayleigh number written by the product of Grashof number by Prandtl number can be used in order to measure the stability of the fluid related to the heat flux and diffusivity of viscosity. Froude number written by the ratio of gravity force to inertia force can be used in order to measure the stability of the nonhomogeneous fluid related to the density difference. As the result of calculating the parameters governing stability, the interface stability on the stratified fluid couldn't be identified below the 70cm height from the bottom of the solar pond, but it could be identified above the 70cm height from it at the inlet port, the middle section and the outlet port. When compared with such the three parameters as Richardson number, Rayleigh number, Froude number, the calculated result was in accord with them at inlet port, the middle section and the outlet port. Henceforth, it is learned that even though any of the three parameters is used for the purpose of measuring the interface stability on the stratified fluid, the result will be the same with them. It is concluded that all the use of Richardson number, Rayleigh number, and Froude number, is desirable and infallible to measure the interface stability on the stratified fluid in the case of considering the exist of the fluid flow and the heat flux like the model of the solar pond.

• 대한원격탐사학회지
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• 제28권3호
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• pp.307-318
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• 2012

To understand forest structures, the Geoscience Laser Altimeter System (GLAS) instrument have been employed to measure and monitor forest canopy with feasibility of acquiring three dimensional canopy structure information. This study tried to examine the potential of GLAS dataset in measuring forest canopy structures, particularly maximum canopy height estimation. To estimate maximum canopy height using feasible GLAS dataset, we simply used difference between signal start and ground peak derived from Gaussian decomposition method. After estimation procedure, maximum canopy height was derived from airborne Light Detection and Ranging (LiDAR) data and it was applied to evaluate the accuracy of that of GLAS estimation. In addition, several influences, such as topographical and biophysical factors, were analyzed and discussed to explain error sources of direct maximum canopy height estimation using GLAS data. In the result of estimation using direct method, a root mean square error (RMSE) was estimated at 8.15 m. The estimation tended to be overestimated when comparing to derivations of airborne LiDAR. According to the result of error occurrences analysis, we need to consider these error sources, particularly terrain slope within GLAS footprint, and to apply statistical regression approach based on various parameters from a Gaussian decomposition for accurate and reliable maximum canopy height estimation.

• 융합정보논문지
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• 제8권6호
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• pp.15-20
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• 2018

본 연구는 뉴로피드백 훈련을 적용하여 생활습관을 조절하는 자기조절력과 키 성장간의 상관성을 규명함으로 써 키 성장의 효과적인 중재 방안에 대한 해법을 제시하고자 실시하였다. 이를 위해 키 성장 프로그램을 실시하고 있는 초등학교 2학년~4학년 학생 40명(실험군 20명, 대조군 20명) 대상으로 뉴로피드백 훈련 전 후의 변화를 확인하였다. 실험기간은 3개월간(주 2회), 훈련시간은 1회 30분이였다. 뉴로피드백 훈련을 적용한 실험군과 대조군의 자기조절력 차이를 분석한 후, 키 성장 차이를 비교 분석하였다. 첫째, 뉴로피드백 훈련을 적용한 실험군이 대조군에 비해 자기조절력에 유의미한 변화가 있었다. 둘째, 뉴로피드백 훈련을 적용한 실험군이 대조군에 비해 더 크게 키 성장의 변화가 있었다. 이상의 결과를 종합하면 뉴로피드백 훈련이 성장기 학생들에게 있어 키 성장의 후천적 요인들 중 생활습관을 조절하는 자기조절력에 긍정적인 영향을 미치며, 그로 인해 키 성장에도 긍정적인 영향을 미친다는 것이 확인되었다.

• 한국산림과학회지
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• 제110권1호
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• pp.72-81
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• 2021

본 연구는 다양한 임목 정보를 측정하고 효과적으로 관리하기 위해 스마트폰 애플리케이션과 웹 애플리케이션 서버(Web Application Server, WAS)를 개발하였다. 수고, 방위, 고도, 경사, 위치 좌표는 스마트폰에 내장된 동작센서를 통해 취득된 각도를 삼각법에 적용하여 측정하였으며, 흉고직경 및 거리는 Google AR Core에서 제공하는 AR API(Application Programming Interface)를 응용하여 측정할 수 있도록 하였다. 웹 애플리케이션 서버는 스마트폰이 측정한 데이터를 수신하여 저장, 조회, 출력하고 수목의 위치를 카카오 맵에 표시할 수 있도록 개발하였다. 또한, 개발된 애플리케이션의 정확성을 평가하기 위해 인공 침엽수림에서 잣나무 90본, 천연 혼효림에서 무작위로 90본을 선정하여 버텍스 및 윤척과 비교하였다. 비교 결과, 흉고직경과 수고 모두 95% 수준에서 유의한 결과를 나타내었으며, 흉고직경의 경우 인공 침엽수림이 평균 0.6745 cm, 천연 혼효림에서는 평균 1.0139 cm의 오차를 보였다. 수고는 인공 침엽수림이 평균 0.6714 cm, 천연 혼효림은 평균 1.3297 m의 오차를 보였다.

• 한국전문물리치료학회지
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• 제28권2호
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• pp.154-160
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• 2021

Background: Theoretically, balance is affected by the height of center of mass (COM) during quiet standing. However, no one examined this in humans with variables derived from the center of pressure (COP). Objects: We have conducted balance experiment to measure COP data during quiet standing, in order to examine how the COP measures were affected by the height of COM, vision, floor conditions, and gender. Methods: Twenty individuals stood still with feet together and arms at sides for 30 seconds on a force plate. Trials were acquired with three COM heights: 1% increased or decreased, and not changed, with two vision conditions: eyes closed (EC) and eyes open (EO), and with two floor conditions: unstable (foam pad) and stable (force plate) floor. Outcome variables included the mean distance, root mean square distance, total excursion, mean velocity, and 95% confidence circle area. Results: All outcome variables were associated with the COM height (p < 0.0005), vision (p < 0.0005), and floor condition (p < 0.003). The mean velocity and 95% confidence circle area were 5.7% and 21.8% greater, respectively, in raised COM than in lowered COM (24.6 versus 23.2 mm/s; 1,013.4 versus 832.3 mm²). However, there were no interactions between the COM height and vision condition (p > 0.096), and between the COM height and floor condition (p > 0.183) for all outcome variables. Furthermore, there was no gender difference in all outcome variables (p > 0.186). Conclusion: Balance was affected by the change of COM height induced by a weight belt in human. However, the effect was not affected by vision or floor condition. Our results should inform the design of balance exercise program to improve the outcome of the balance training.

• 한국멀티미디어학회논문지
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• 제21권8호
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• pp.864-875
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• 2018

In this paper, we propose a measurement method for height of white light scanning interferometer using deep learning. In order to measure the fine surface shape, a three-dimensional surface shape measurement technique is required. A typical example is a white light scanning interferometer. In order to calculate the surface shape from the measurement image of the white light scanning interferometer, the height of each pixel must be calculated. In this paper, we propose a neural network for height calculation and use virtual data generation method to train this neural network. The accuracy was measured by inputting 57 actual data to the neural network which had completed the learning. We propose two new functions for accuracy measurement. We have analyzed the cases where there are many errors among the accuracy calculation values, and it is confirmed that there are many errors when there is no interference fringe or outside the learned range. We confirmed that the proposed neural network works correctly in most cases. We expect better results if we improve the way we generate learning data.

• The Journal of Korean Physical Therapy
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• 제23권2호
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• pp.1-5
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• 2011

Purpose: This study examined the difference in the center of pressure (COP) displacement time in older adults according to the obstacle height during stance at each sub.phase when crossing obstacles. Methods: Fifteen older adults were enrolled in this study (${\geq}65$ years of age). The F-scan was used to measure the COP displacement time when crossing a 0, 10 and 40cm obstacle, and the stance phase was divided into 4 sub-phases according to the foot contact pattern. Results: During the stance phase, the COP displacement time increased with increasing obstacle height. During the mid-stance, terminal stance and pre-swing except for the loading response, there were significant differences in the COP displacement time according to the obstacle height. Conclusion: This study suggests that older adults show differences in the COP displacement time according to the stance sub-phase while crossing obstacles, and they use different mechanisms according the sub-phases to maintain balance during obstacle crossing.