• Transactions of the Korean Society of Mechanical Engineers A
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• v.39 no.1
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• pp.71-77
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• 2015

Ultrasonic imprinting is a micropattern replication technology for a thermoplastic polymer surface that uses ultrasonic vibration energy; it has the advantages of a short cycle time and low energy consumption. Recently, ultrasonic imprinting has been further developed to extend its functionality: (i) selective ultrasonic imprinting using mask films and (ii) repetitive ultrasonic imprinting for composite pattern development. In this study, selective ultrasonic imprinting was combined with repetitive imprinting in order to replicate versatile micropatterns. For this purpose, a repetitive imprinting technology was further extended to utilize mask films, which enabled versatile micropatterns to be replicated using a single mold with micro-prism patterns. The replicated hybrid micropatterns were optically evaluated through laser light images, which showed that versatile optical diffusion characteristics can be obtained from the hybrid micropatterns.

• Journal of radiological science and technology
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• v.38 no.1
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• pp.7-15
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• 2015

A ultrasonic probe is very important in medical ultrasonic image, but the frequency of probe defects are often. Therefore practical tools for probe based ultrasonic QA should be developed. Advanced research on the effects of the probe defects on the quality of ultrasonic images is required. This study has investigated the effects of the defects in the probe elements influence Doppler images in the medical ultrasonic scanners. Especially the defects in a set of adjacent elements(SAE) electrically disconnected influence Doppler images were tested. The results show Doppler brightness and velocity became rapidly reduced as the defected elements is located centrally, as the defected elements is activated. The more the defected elements increased, the more Doppler brightness and velocity increased. As a set of the element disconnected moved, it appeared Doppler velocity starting to decrease and then was followed by brightness. The strength is not consistent with the velocity in the number and location of the defected elements. The defects in the probe elements influence Doppler velocity when the defected elements got out of the elements activated at Doppler mode.

• Journal of radiological science and technology
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• v.26 no.2
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• pp.43-47
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• 2003

Colorectal cancer produce focal mass or segmental thickening which can be detected with sonography. The purpose of this study was to describe sonographic findings of colorectal cancer. we reviewed sonograms of 51 patients with colorectal cancer in whom sonography was performed before colon study. In 51 patients who had more common coloretal cancer 27cases(53%) had 40 to 50 years of age(60%). Sonographic findings included segmental thickening 42cases, or irregular mass 9 cases. With careful examination, these findings can be detectable, and therefore bowel should be carefully examination in patients with sign and symptoms suggesting carcinoma of the colon and rectum.

• Journal of radiological science and technology
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• v.38 no.4
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• pp.443-449
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• 2015

An ultrasound probe has a big impact on Doppler images even though it has very high risk of frequent function-breakdowns occurring in medical ultrasound scanners. This study experimentally analyses the impacts of an ultrasonic probe's defected elements on power & color Doppler images. The results show that, the bigger the size of defected probe elements is, and the closer a group of action elements is to the center, the more the brightness of images and the velocity of Doppler diminish. When elements' defects increase in color & power Doppler images, false images are formed to be mistaken for blood-vessel plaque in neighboring regions. Accordingly, whenever element defects are suspected, we need check-up process in B-mode. From this respective, it is advisable to have primary interest in a probe and carry out continuous probe QA for ultrasonography.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.1198-1202
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• 2004

초음파를 이용한 측정은 하천의 반대편에 흐름방향에 경사지게 초음파를 발사하여 다시 반사되어 오는 시간차를 기록함으로써 주어진 길이에서 유속을 연속적으로 측정하는 것이다. 하류로 내려가는 음파는 음향 측선(acoustic path)과 평행한 유속 성분 때문에 상류로 올라가는 음파보다 빠른 속도를 가진다. 탄천 및 괴산댐에 초음파 유량 측정시스템을 시험 설치하고 운영 결과를 검토하였다. 시험적용결과 연속적인 유량자료 획득이 가능하였으며, 기존 유속면적법 대비 $4.21\%$의 상대오차를 지니고 있어 기존 방법과 비교적 일치하는 측정결과를 나타냈다. 또한 지표유속(Index Velocity)를 활용한 단일회선 유량산정법을 검토한 결과, 다회선에 의해 운영한 결과와 평균 $2.9\%$의 상대오차를 지니고 있었다. 이 방법은 조석구간 및 배수영향을 받는 구간에서 작은 비용으로 연속유량자료를 획득할 수 있는 방법으로 판단된다. 시험적용 결과 개선해야 할 사항으로는 안정적인 자료 획득을 위한 초음파 변환기의 개선, 자료의 필터링 기술의 정밀화, 그리고 유량산정 방법에서 정확도 향상 기술 개발 등이 도출되었다. 초음파 유량 측정시스템은 자료의 연속성을 확보할 수 있는 점에서 매우 중요한 의미를 지니고 있다. 지금까지의 연속 유량 산출법은 연속적인 수위를 측정하고 각 수위에 따른 유량 측정 후 수위-유량관계를 통하여 연속적인 유량을 산출하였다. 그러나 초음파 유량 측정 시스템은 직접 유속과 수위를 측정하여 연속유량이 산출되기 때문에 연속유량 산출에 비교적 간편하다고 할 수 있다. 또한 정확도 면에서 기존 유량 측정법인 유속-면적법의 불확실도 $5\%\~10\%$에 비교하여 $5\%$ 내외의 정확도 수준을 지니고 있어 정확도 향상을 기대할 수 있다. 경제적인 측면에서도 매년 측정사업에 소요되는 비용과 비교하였을 때 장기적으로는 경제적인 방법이 될 수 있다.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2004.05b
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• pp.269-272
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• 2004

The respiration measurement method using the ultrasound sensor hardly gets an influence of an error of inertia and pressure and it is a respiratory detection device available semi-permanently. This device measures the amount and flow of respiration through using a delivery speed difference of the ultrasound waves that are a return format by the pneumatic stream that is a flogging of ultrasound waves during transmission and receipt as having used a characteristic of ultrasound waves. In this paper, it improved sensitivity of a signal to happen during transmission and receipt of a sensor because measurement must be performed with a patient to the center and measurement was played in a weak breathing so that it was possible.

• Journal of the Institute of Convergence Signal Processing
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• v.12 no.1
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• pp.67-75
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• 2011

This paper presents the systematic optimal design of an overlapped ultrasonic sensor ring for high performance obstacle detection using effective beam overlap. Basically, a set of low directivity ultrasonic sensors of the same type are arranged in a circle at regular intervals with their beams overlapped. First, both real and simplified beam patterns of an ultrasonic sensor and several sensor models for obstacle position estimation within its beam pattern are introduced. Second, the obstacle detection range of an overlapped ultrasonic sensor ring and its simple sensor model for obstacle position estimation are described. Third, for both conic and non-conic shaped beam pattern, the design indices of an overlapped ultrasonic sensor ring for minimal positional uncertainty in obstacle detection are defined. Fourth, the constraints imposed on the structural parameters of an overlapped ultrasonic sensor ring to guarantee non empty beam overlap and to avoid excessive beam overlap are derived. Fifth, the optimal number of ultrasonic sensors for a given radius of an overlapped ultrasonic sensor ring and the optimal radius of an overlapped ultrasonic sensor ring are determined. Throughout this paper, the MA40B8 from Murata Inc. is taken as a representative commercial low directivity ultrasonic sensor.

• Journal of the Korean Society for Nondestructive Testing
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• v.32 no.1
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• pp.41-46
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• 2012

As the development of MEMS/NEMS structure and application technology the demand for an assessment of the mechanical properties have increased. The mechanical properties are mainly evaluated by using tensile test or ultrasonic wave measurement. However, the new technology have been developed such as nano-indentation, guided wave method because they have a limitation in case of a thin plate and thin film. In the study, the guided wave velocities are measured by electromagnetic-acoustic transducer(EMAT), the material properties of thin metallic foils are obtained using optimization process of the theoretical and experimental group velocity of guided wave. The Young's modulus obtained by the optimization process(201.6 GPa), nano-indentation(207.0 GPa) and literature value(203.7 GPa) of a $50{\mu}m$ thick nickel thin plate shows good agreement within 3%.

• Journal of the Korean Society for Nondestructive Testing
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• v.24 no.4
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• pp.371-377
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• 2004

As the turbine running duration in nuclear power plants increases, cracks have been found in the pin finger type blade root area. The nondestructive examination for the blade root area has been carried out by manual ultrasonic examination during the overhaul period, but because of necessity to improve the reliability, we developed an automatic ultrasonic examination system and technique. To demonstrate the performance of the developed automatic ultrasonic examination system, low pressure turbine blades in the 2nd and 3rd stages of nuclear power plants were examined using the developed system. Its applicability nuclear power plant turbine roots of various types was also confirmed.

• Clean Technology
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• v.16 no.2
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• pp.80-87
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• 2010

In this study, micro- and submicron particles of itraconazole, a poorly water-soluble antifungal drug, were prepared for improving its aqueous solubility using an ultrasound-assisted supercritical fluid technique, called SAS-EM. The SAS-EM process used in our experiments was different from the conventional SAS-EM in that the ultrasound was applied directly to the spray nozzle. The effect of the ultrasonic power, temperature, and solvent on the formation of itraconazole particles were investigated. Smaller particles were obtained through our SAS-EM process compared with the ASES process, and the mean particle size decreased as the ultrasonic power increased. Our experimental results confirmed that the ultrasound-assisted supercritical fluid process is an efficient method for producing ultrafine particles.