• 전자공학회논문지S
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• 제35S권6호
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• pp.66-71
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• 1998

본 연구에서 피부계통의 진단에 이용될 수 있는 고해상도 영상진단기를 개발하였으며 개발된 영상진단기는 sector scanning 방식으로서 A-mode, B-mode, M-mode의 80${\mu}m$ 축방향, 250${\mu}m$ 축방향 해상도로 $5mm {\times} 5mm$의 인체 단면 영상을 초당 20frame으로 나타낸다. 이 영상장치는 대부분의 피부학(dermatology) 계통의 질환에 그 병리학적인 연구에 이용될 수 있을 뿐만 아니라 안과(ophthalmology)나 치과(odontology) 계통의 병리학적인 판단에도 도움을 줄 수 있다고 생각되며 또한 피부미용(dermato-cosmetology)을 위한 분야에도 응용 가능하다.

• 한국의학물리학회지:의학물리
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• 제24권3호
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• pp.183-190
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• 2013

광 음향 영상 장치는 최근 들어 연구와 개발이 활발히 진행 중이며 암을 조기 진단할 수 있는 장치로서의 가능성을 보이고 있다. 본 연구에서는 유방암 조기 진단을 위하여 광 음향 단층촬영 방식의 영상 장치를 개발하고 팬텀을 이용하여 그 유용성을 평가하고자 한다. 튜브 팬텀과 닭 가슴살 팬텀을 제작하고 이동 평균 필터와 3~6 MHz의 대역폭을 갖는 대역 통과 여파기를 설계하여 잡음을 제거하고 시간 지연 빔 형성(delay-and-sum beamforming) 알고리즘을 이용하여 광음향 영상을 재구성 하였다. 연구 결과 영상의 재구성에 있어서 빔 형성 알고리즘을 적용하기 전에 대역 통과 여파기와 같은 신호 처리가 효과적임을 보였다.

• 한국음향학회지
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• 제41권5호
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• pp.534-544
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• 2022

초음파진단기는 실시간으로 손쉽고 안전하게 환자의 병변을 관찰할 수 있는 등의 다양한 장점으로 인해 병원, 의원 등의 의료현장에서 널리 활용되고 있다. 이 초음파진단기 신호처리 블록 중 하나인 빔포머는 초음파진단기 영상의 화질을 결정하는 부분 중 하나이다. 초음파진단기 기술의 발전과 더불어 이 빔포머와 관련된 기술들도 장기간 많은 발전을 이루어 왔는데, 이 기술들 중 하나의 주요 방법인 합성구경영상법(Synthetic Aperture Imaging method, SAI)은 프로브를 통해 수신한 신호가 운반해 온 환자로부터의 정보를 최대로 활용하기 위한 방법으로, 1990년대 경 최초로 초음파진단기에 도입된 이래 획기적 화질 향상에 기여해 왔고, 수십년동안 다양한 형태의 발전을 거쳐왔다. 이 논문에서는 이러한 진화과정을 살펴보고, 이 기술의 미래의 발전 방향을 예상해 본다.

• 대한정형도수물리치료학회지
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• 제29권2호
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• pp.69-75
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• 2023

Purpose: This study examined the distance between the coracoid process and the humeral head using an ultrasonography device when shoulder active contraction were applied according to the guided direction in the end range of shoulder mobilization. This study aims to provide essential data on treating shoulder disease patients. Methods: The subjects of this study were 20 adults with healthy shoulder joints. ultrasonography (US) equipment was used to examine shoulder joint mobilization under two conditions: (1) anteroposterior (AP) joint mobilization and (2) superoinferior (SI) joint mobilization. Shoulder active contraction was assessed in the end range. The distance between the coracoid process and the humeral head was measured. A linear probe was used for US; the frequency was set to 7.5MHz, and the US image display method was set to B-mode. The US measurement values were measured in (1) the starting position, (2) the end range position, and (3) the end range position of the shoulder active contraction, and the moving distance was drawn in a straight line through the US image. The distance was determined as the measurement value, and the average values were compared. Reults: The results were as follows: (1) the measured AP Joint mobilization increased by an average of .52cm from the end range of the joint mobilization with shoulder active contraction; (2) the measured SI Joint mobilization increased by an average of .49cm from the end range of the joint. Conclusion: When shoulder mobilization is applied, the distance between the coracoid process and the humeral head increases when muscle contraction occurs through shoulder active contraction in the end range, according to the therapist's guidance. Therefore, shoulder mobilization combined with shoulder active contraction is an effective treatment method for patients with shoulder injuries.

• Journal of Advanced Marine Engineering and Technology
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• 제28권6호
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• pp.922-930
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• 2004

An experimental investigation was performed to study on the generation of air bubble and air core with swirling flow in a horizontal cicular tube. To determine some characteristics of the flow, 2D PIV technique is employed for velocity measurement in water. The experimental rig is manufactured from an acryl tube. The test tube diameter of 80mm, and a length of 3000mm. The used algorithm is the gray leve cross-correlation method(Kimura et al. 1986). An Ar-ion laser is used and the light from the laser(500mW) passes through a probe to make two-dimensional light sheet. In order to make coded images of the tracer particles on one frame, an AOM(Acoustic-Optical Modulator) is used. The maximum axial velocities showed near the test tube wall at y/D =0.1 and y/D =0.9 along the test tube. The higher Reynolds number increase, the lower axial velocities are showed in the center of the test tube. The air bubbles are generated from Re =10,000 and developed into air core from the recirculating water pump rpm equal 30Hz. The pressure and temperature are measured across the test tube at X/D=3.33.

• 한국가시화정보학회지
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• 제1권1호
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• pp.64-74
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• 2003

An experimental study was carried out to investigate the effect of periodic blowing and suction on a turbulent boundary layer. Particle image velocimetry (PIV) was used to probe the characteristics of the flow. The local forcing was introduced to the boundary layer via a sinusoidally-oscillating jet issuing from a thin spanwise slot. Three forcing frequencies (f$^{+}$=0.044, 0.066 and 0.088) with a fixed forcing amplitude (A$^{+}$=0.6) were employed at $Re_{=690. The effect of the forcing angles ($\alpha$=60$^{\circ}$ , 90$^{\circ}$ and 120$^{\circ}$ ) was investigated under the fixed forcing frequency (f$^{+}$=0.088). The PIV results showed that the wall region velocity decreases on imposition of the local forcing. Inspection of phase-averaged velocity profiles revealed that spanwise large-scale vortices were generated in the downstream of the slot and persist further downstream. The highest reduction in skin friction was achieved at highest forcing frequency (f$^{+}$=0.088) and a forcing angle of $\alpha$=120$^{\circ}$. The spatial fraction of the vortices was examined to analyze the skin friction reduction.

• Journal of Astronomy and Space Sciences
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• 제32권2호
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• pp.161-166
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• 2015

Analysis of lunar samples returned by the US Apollo missions revealed that the lunar highlands consist of anorthosite, plagioclase, pyroxene, and olivine; also, the lunar maria are composed of materials such as basalt and ilmenite. More recently, the remote sensing approach has enabled reduction of the time required to investigate the entire lunar surface, compared to the approach of returning samples. Moreover, remote sensing has also made it possible to determine the existence of specific minerals and to examine wide areas. In this paper, an investigation was performed on the reflectance distribution and its trend. The results were applied to the example of the double ray stretched in parallel lines from the Tycho crater to the third-quadrant of Mare Nubium. Basic research and background information for the investigation of lunar surface characteristics is also presented. For this research, resources aboard the SELenological and ENgineering Explorer (SELENE), a Japanese lunar probe, were used. These included the Multiband Imager (MI) in the Lunar Imager/Spectrometer (LISM). The data of these instruments were edited through the toolkit, an image editing and analysis tool, Exelis Visual Information Solution (ENVI).

• 대한기계학회논문집B
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• 제25권7호
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• pp.915-922
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• 2001

A new phase-average technique using instantaneous velocity fields obtained by a PIV method has been developed. The technique tracks vorticity centers and estimates the value of circulation for a chosen domain. The locations of vortex-centers and the magnitudes of circulation are matched together then showing a sine wave feature due to the periodic vortex shedding from the circular cylinder. Ensemble averaged and phase averaged velocity fields are successfully measured for the circular cylinder wake where Reynolds number is 3900 based on free stream velocity and cylinder diameter. The convection velocities of the vortices center and the vortex shedding frequency were measured by a single hot-wire probe.

• 한국가시화정보학회지
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• 제3권1호
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• pp.78-89
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• 2005

An experimental study was carried out to investigate the effect of local ultrasonic forcing on a turbulent boundary layer. Stereoscopic particle image velocimetry (SPIV) was used to probe the characteristics of the flow. A ultrasonic forcing system was made by adhering six ultrasonic transducers to the local flat plate. Cavitation which generates uncountable minute air-bubbles having fast wall normal velocity occurs when ultrasonic was projected into water. The SPIV results showed that the wall normal mean velocity is increased in a boundary layer dramatically and the streamwise mean velocity is reduced. The skin friction coefficient (C$_{f}$) decreases 60$\%$and gradually recovers at the downstream. The ultrasonic forcing reduces wall-region streamwise turbulent intensity, however, streamwise turbulent intensity is increased away from the wall. Wall-normal turbulent intensity is almost the same near the wall but it increases away from the wall. In the vicinity of the wall, Reynold shear stress, sweep strength and production of turbulent kinetic energy were decreased. This suggests that the streamwise vortical structures are lifted by ultrasonic forcing and then skin friction is reduced.

• 한국정밀공학회지
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• 제13권2호
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• pp.68-75
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• 1996

More accurate inspection method for facilities of nuclear power plants is required to guarantee the continuous and stable energy supply. The portion of inspection for pipes and pressure vessels is relatively big in the power plants. Conventional inspection methods using ultrasonic wave, x-ray and eddy current for nondestructive testing in nuclear power plants have been performed as the method of contact with objects to be inspected. With this reason these methods have been taken relatively much time, money and manpower. And the area to be inspected is limited by the location of probe or film. These difficulties make the inspection into a time-consuming work. We propose an optical defect detection method using phase shifting realtime holographic interferometry. This method has an advantage that the inspection can be performed at a time for relatively wide area illuminated by the laser beam, a coherent light source and can help an inspector recognize not only defects but also the high stressed areas. In this paper we show that the quantitative measurement using holographic interferometry and image processing for defect in pressure vessels is possible.