• Proceedings of the KSME Conference
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• 2000.04a
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• pp.411-414
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• 2000

Optical Triangulation Probes (OTPs) are widely used for their simple structure. high resolution, and long operating range. However, errors originating from speckle, inclination of the object, source power fluctuation, ambient light, and noise of the detector limit their usability. In this paper, we propose new design criteria for an error-reduced OTP. The light source module for the system consists of an incoherent light source and a multimode optical fiber for eliminating speckle and shaping a Gaussian beam Intensity profile. A diffuse-reflective white copy paper, which is attached to the object, makes the light intensity distribution on the change-coupled device(CCD). Since the peak positions of the intensity distribution are not related to the various error sources, a sub-pixel resolution signal processing algorithm that can detect the peak position makes it possible to construct an error-reduced OTP system

• Journal of Sensor Science and Technology
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• v.18 no.4
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• pp.322-326
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• 2009

To estimate the measurement uncertainty for industrial platinum resistance thermometers(IPRTs) made with 3-wire connection, the immersion temperature profile was investigated using a liquid bath. Two types of IPRTs having lead wires made of silver and nickel were constructed and the immersion profiles were measured at temperatures from -50 $^{\circ}C$ to 250 $^{\circ}C$ using 3-wire and 4-wire method. As immersion depth and temperature increased, the resistances measured by 3-wire method increased linearly but not for 4-wire method. To calibrate a 3-wire IPRT, the immersion effect must be accounted for. We propose a linear equation to assess correctly the measurement uncertainty.

• Proceedings of the KIEE Conference
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• 1998.07e
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• pp.1653-1655
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• 1998

In this paper, measurement and analysis of ELF electric and magnetic fields in the vicinity of 22.9[kV] distribution line have been performed. The height of measuring point from the earth's surface was 1[m], and the distance between the device and the operator was more than 3[m]. The experiments have been carried out by lateral profile, and we have made use of FIELDS program for the sake of comparision the experimental data with the theoretical value. Electric and magnetic fields intensity were strong under a distribution line, and were inversely proportional to lateral distance. The profiles of electric field were M shape and those of magnetic field were $\cap$ shape. Electric and magnetic fields intensity were increased with increasing the measurement height.

• Journal of the Optical Society of Korea
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• v.13 no.4
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• pp.464-467
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• 2009

The grating projection method with phase-shifting technique is very useful in measuring the 3-dimensional (3D) shape with high accuracy and speed. In this work, we have developed an ultra high-speed digital laser grating projection system using a high-power laser diode and a highsensitivity CMOS camera. With our system, the optical measurement required to find out the profile of a 3D object could be carried out within 2.6 ms, which is a significant ($\sim$10 times) improvement compared with those of the previous studies.

• The Proceedings of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.13 no.2
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• pp.178-178
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• 1999

In recent years, the electromagnetic environments are varied with the increase of power consumption and the spread of household electric appliances. Most of the interests to date have concentrated in the area of human health effects associated with exposure to power frequency electric and magnetic fields, and thus the precise measurement and analysis are required. In this paper, the measurements and analysis of the extremely low frequency(ELF) electric and magnetic fields produced by actual 22.9[kV] distribution lines were performed. The experiments have been carried out by lateral profile, and the theoretical analyses were made by use of FIELDS program for the sate of comparison with the experimental data. Electric and magnetic field intensity were strong under power distribution lines, and were inversely proportional to lateral distance. The profiles of electric and magnetic fields were M and ∩ shapes, respectively, and the measured data were good in agreement with the theoretical results. Both the electric and magnetic field intensity were increased with increasing the measurement height.

• Proceedings of the Korean Nuclear Society Conference
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• 1997.10a
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• pp.329-334
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• 1997

A tomography algorithm to maximize the entropy of image using Lagrangian multiplier technique and conjugate gradient method has been designed for the measurement of 2D spatial distribution of intense neutral beams of KSTAR NBI(Korea Superconducting Tokamak Advanced Research Neutral Beam Injector) which is now being designed. A possible detection system was assumed and a numerical simulation has been implemented to test the reconstruction quality of given beam profiles. This algorithm has the good applicability for sparse projection data and thus, can be used for the neutral beam tomography.

• Journal of Korean Society for Atmospheric Environment
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• v.11 no.4
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• pp.315-321
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• 1995

The purpose of this report is to describe the lidar measurement of depolarization ratios of particulate matter (Depolarization Ratio of Yellow Sand) and to discuss the transformation of aerosols due to Yellow Sand event. The scattering profile shows high level during Yellow Sand event and scattering layers are thicker as compared to other seasons in about 3 .sim. 8km, and the values and mode height of scattering ratio corresponed with depolarization ratio. A distribution of total depolarization ratio during the observation period was 44.7 percent among total cases of 0.03 < Dt < 0.5 with scattering ratio > 30 and relative humidity < 30 was satisfied (popular Yellow Sand type).

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2001.10a
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• pp.592-595
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• 2001

원거리에서 무접촉 거리 계측(ranging)은 군용 장비나 건설, 항해, 자동화 등에 매우 중요하다. 계측방식은 active와 passive 방식으로 구분되는데, active방식은 laser나 microwave, 초음파 등의 time of flight를 이용하거나 레이저 조사(illumination)에 대한 카메라 영상을 해석하는 등의 다양한 방식이 있으나 장치가 복잡하고, passive 방식은 stereo camera의 양안 영상을 이용하거나 focus 특성을 이용하는 방식 등이 있으나 대부분 연산 시간이 많이 요구된다. 본 연구에서는 수동식 스테레오 카메라에서 양안시차를 추출하여 triangulation으로 목표점(target point)의 거리를 측정하는 것을 기본 방식으로 하여, 기존 거리 산출 방식에서 연산 시간이 많이 소요되는 연산 과정을 효율적이고 고속으로 수행할 수 있도록 새로운 방식을 제안하였다. 즉, 목표점에서의 양안 edge 영상을 구하며, 이 영상의 accumulation profile을 correlation하여, 거리 연산의 핵심 요소인 양안 시차를 고속으로 추출하는 알고리즘을 제안하였다. 또한, 제안 방식의 효율성을 실험 결과를 통하여 보였다.

• Transactions of the Korean Society of Mechanical Engineers B
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• v.24 no.7
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• pp.924-929
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• 2000

This paper addresses a new technique of measuring the mean flow velocity over the cross sectional area of the pipe using sound field reconstruction. When fluid flows in the pipe and two plane waves propagate oppositely through the medium, the flow velocity causes the change of wave number of the plane waves. The wave number of the positive going plane wave decreases and that of negative going one increases in comparison to static medium in the pipe. Theoretical backgrounds of this method are introduced in detail and the measurement of mean flow velocity using the sound field reconstruction is not affected by velocity profile upstream of microphones.

• 유체기계공업학회:학술대회논문집
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• 1999.12a
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• pp.264-271
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• 1999

The present experimental study is aimed to investigate the flow characteristics of the high-speed flow field within hot-water pump by PIV(Particle Image Velocimetry). As multi-point simultaneous velocity acquisition, 2-D PIV system based upon the two-frame gray-level cross correlation method is adopted using PC frame-grabber and simple video system. Gated image intensifier CCD Camera to cope with illumination problem is arranged for accurate PIV measurement of high-speed complex flow. The velocity vector distribution, velocity profile, and kinetic energy are represented quantitatively at the full-scale region for the deeper understanding of the unsteady flow characteristics in a pump.