• Current Optics and Photonics
• /
• v.5 no.5
• /
• pp.532-537
• /
• 2021

We present a compact endoscopic probe in a needle form which has a fast beam-scanning capability for optical coherence tomography (OCT). In our study, a beam-scanning OCT imaging needle was fabricated with a 26G syringe needle (0.46 mm in outer diameter) and a thin OCT imaging probe based on the stepwise transitional core (STC) fiber. The imaging probe could freely rotate inside the needle for beam scans. Hence, OCT imaging could be performed without rotation or translation of the needle body. In our design, the structural integrity of the needle's steel tubing was preserved for mechanical robustness. Probing the optical signal was performed through the needle's own window formed at the end. For hand-held operation of our imaging needle, a light and compact scanner module (130 g and 45 × 53 × 60 mm³) was devised. Connected to the imaging needle, it could provide rotational actuation driven by a galvanometer. Because of its finite actuation range, our scanner module did not need a fiber rotary joint which might add undesirable complexity. The beam scan speed was 20 Hz and supported 20 frames per second at the maximum for endoscopic OCT imaging.

• Journal of Advanced Marine Engineering and Technology
• /
• v.26 no.3
• /
• pp.353-361
• /
• 2002

The tip leakage flow passing through the clearance between rotor blade tip and casing shroud has been known to occupy an important portion of the rotor overall loss. In this study, flow characteristics in axial flow rotors with different tip clearances is investigated by experimental and numerical methods. The experimental study was carried out to measure static pressure and velocity profiles at the real rotating test rig. The axial flow rotors used for the experiments have ten blades and three different rotor diameter. The tip clearance heights are 1mm, 3mm, and 4.5mm. Measurements were done using spherical type five-hole probe by non-nulling method. The numerical study was carried out to calculate pressure distributions and velocity vectors at the same condition as the experiments in the flow fields of axial flow rotors using Phoenics code.

• Economic and Environmental Geology
• /
• v.17 no.4
• /
• pp.315-320
• /
• 1984

The newly discovered minerals found during 30 years have been discovered with election microprobe analysis, and several other new minerals have been described largely on the basis of probe analysis. Widely used types of instrument are the wavelength dispersive spectrometer (WDS) and the energy dispersive Spectrometer (EDS), with emitted X-ray dispersed by a curved crystal that is arranged to satisfy the Bragg equation ($n{\lambda}=2dsin{\theta}$). Atomic Nos of Z 4 to 92 can be analyzed quantitatively if they present in amount exceeding 50~100ppm. The application of the microprobe in mineralogical and geological research is quantitative chemical analysis of grains as small as a few microns in diameter, individual grains in a rock or can be analyzed in thin section and polished section, analysis can be made comparatively short time, methods in non-destructure, to photographical and crystallographical information. This paper was written in order to document data evaluation procedure for quantitative energy dispersive election probe analysis.

• Journal of the Korean Society of Industry Convergence
• /
• v.2 no.1
• /
• pp.121-130
• /
• 1999

It is necessary to measure pressure, temperature, chemical equilibrium and the shape of flame in order to understand the combustion process in a combustion chamber. In particular, the flame formulation and combustion process of divided combustion chamber are different from those of a single chamber, And the variable diameter of a jet hole can effect not only physical properties like ejection velocity, temperature and time of combustion but also a chemical property like the reaction mechanism. Accordingly temperature is one of the most important factors which influence the combustion mechanism. This paper observed shape of flame by using the schlieren photographs and measured the pressure in a combustion chamber and the reaching time of the flame by ion probe By doing these, we investigation the formulation of the flame and the process of propagation. These measurement methods can be advanced in understanding the combustion process and process and propagation of flame.

• Journal of the Korean Institute of Telematics and Electronics D
• /
• v.35D no.10
• /
• pp.7-12
• /
• 1998

The wave reflections from several types of open-ended coaxial probes contacted on the various materials have been analyzed precisely by using the finite-difference time-domain(FDTD) technique in this paper. Due to the coordinate transformation from three-dimension to two-dimension, the computation was performed very efficiently. It was found that the reflection from an open-ended coaxial probe reduces as frequency or diameter of a coaxial line increases. The reflections from multi-layered media were also analyzed by the FDTD method. This analysis technique was verified by comparison with measurements and theoretical computations.

• Proceedings of the Korean Society of Soil and Groundwater Environment Conference
• /
• 2003.04a
• /
• pp.111-114
• /
• 2003

A new monitoring system has been developed for in-situ and realtime measurement of ozone transport in unsaturated porous media using a fiber optic sensor. The calibration of the fiber optic transflection dip probe (FOTDP) system was successfully carried out at various ozone concentrations using a column with length of 30 cm and diameter of 5 cm packed with glass beads, which don't react with gaseous ozone. The breakthrough curves (BTCs) of ozone was obtained by converting the normalized intensity into ozone concentration. The FOTDP system reflected the ideal transport phenomena of gas phase ozone at various flow rates. The FOTDP system worked well for in-situ monitoring of gas phase ozone at various water saturations and in presence of SOM. However, the FOTDP system did not measure the ozone concentration at more than 70% water saturation.

• Proceedings of the Korean Vacuum Society Conference
• /
• 2011.02a
• /
• pp.213-213
• /
• 2011

DC arc plasmatron is powerful plasma source to apply etching and texturing processing. Even though DC arc plasmatron has many advantages, it is difficult to apply an industry due to the small applied area. To increase an effective processing area, we suggest a DC-RF hybrid plasma system. The DC-RF hybrid plasma system was designed and made. This system consists of a DC arc plasmatron, RF parts, reaction chamber, power feeder, gas control system and vacuum system. To investigate a DC-RF hybrid plasma, we used a Langmuir probe, OES (Optical emission spectroscopy), infrared (IR) light camera. For RF matching, PSIM software was used to simulate a current of an impedance coil. The results of Langmuir probe measurements, we obtain a homogeneous plasma density and electron temperature those are about $1{\times}1010$ #/cm3 and 1~4 eV. The DC-RF hybrid plasma source is applied for plasma etching experimental, and we obtain an etching rate of 10 ${\mu}m$/min. through a 90 mm of reaction chamber diameter.

• Journal of the Korean Society of Marine Environment & Safety
• /
• v.18 no.3
• /
• pp.273-278
• /
• 2012

The use of Al alloys instead of fiber-reinforced plastic(FRP) in ship construction has increased because of the advantages of Al-alloy ships, including high speed, increased load capacity, and ease of recycling. This paper describes the effects of probe diameter on the optimum friction stir welding conditions of 5456-H116 alloy for leisure ship, measured by a tensile test. In friction stir welding using a probe diameter of 5 mm under various travel and rotation speed conditions, the best performance was achieved with a travel speed of 61 mm/min. Using a probe diameter of 6 mm, rotation speeds of 170-210 rpm, and a travel speed of 15 mm/min produced a rough surface and voids because of insufficient heat input produced by the low rotation speed. At 500-800 rpm, chips were observed, although there were no voids, and the weld surface was excellent. However, at 1100-2500 rpm, many chips were produced due to excessive heat input. Heat effects were very evident on the bottom. For a travel speed of 15 mm/min, heat input caused by friction increased as the rotation speed increased. The mechanical characteristics were degraded by accelerated softening due to increasing heat input.

• Journal of the Korean Magnetics Society
• /
• v.15 no.5
• /
• pp.292-297
• /
• 2005

Steam generator of a nuclear power plant has important rolls for the heat transfer and the isolation of radioactive materials. So bursting of the steam generator tube is directly related to the accident of nuclear power plants. Incone1600 has been used for the steam generator tube material. The material shows non-magnetic and metallic properties, eddy current NDT method has been employed for defects detection. In this work, a differential type of eddy current probe was developed to improve resolution of defect detection. To verify properties of the developed differential type eddy current probe, we have made reference material with SUS304 which has similar magnetic and electrical properties of Inconel600. Using the developed differential type eddy current probe, we can detect defect size of 0.25 mm in diameter and 0.2 mm in depth (volume of $1{\times}10^{-3}\;mm^3$) with the reference material.

• International Journal of Precision Engineering and Manufacturing
• /
• v.9 no.3
• /
• pp.27-32
• /
• 2008

This paper describes a contact atomic force microscope (AFM) that can be used for high-speed precision measurements of microstructured surfaces. The AFM is composed of an air-bearing X stage, an air-bearing spindle with the axis of rotation in the Z direction, and an AFM probe unit. The traversing distance and maximum speed of the X stage are 300 mm and 400 mm/s, respectively. The spindle has the ability to hold a sample in a vacuum chuck with a maximum diameter of 130 mm and has a maximum rotation speed of 300 rpm. The bandwidth of the AFM probe unit in an open loop control circuit is more than 40 kHz. To achieve precision measurements of microstructured surfaces with slopes, a scanning strategy combining constant height measurements with a slope compensation technique is proposed. In this scanning strategy, the Z direction PZT actuator of the AFM probe unit is employed to compensate for the slope of the sample surface while the microstructures are scanned by the AFM probe at a constant height. The precision of such a scanning strategy is demonstrated by obtaining profile measurements of a microstructure surface at a series of scanning speeds ranging from 0.1 to 20.0 mm/s.