• Title/Summary/Keyword: 초음파 전파 속도

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A Study on the Effectiveness of Diagnostic Ultrasound Transmission Media (초음파진단시 초음파 전파매질의 유용성에 관한 연구)

  • Lee, Hye Nam;Lim, Cheong-Hwan
    • Proceedings of the Korea Contents Association Conference
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    • 2014.11a
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    • pp.187-188
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    • 2014
  • 초음파 전파 매개물은 초음파의 손실 없는 투과력을 위한 1차적인 목적 이외에 피부위에서 탐촉소자의 부드러운 이동을 위한 부가적인 목적이 있다. 본 연구는 제형이 다른 진단초음파 전파매개물이 갖는 피부 윤활성, 피부 보습성, 건조속도 등의 초음파 매개물의 특징을 측정하고 비교하였다. 마찰계수는 점도가 높을수록 높았으며 제제의 건조속도는 고분자 수화젤이 가장 높았다. 오일 함유량이 많을수록 수분증발이 나타나지 않았다. 피부수분함량에서는 저점도 에멀전이 높은 수분함량을 나타냈으며 수분함량 감소 정도가 가장 완만히 나타났다. 오일성분을 적절히 사용한 에멀전 형태의 초음파 전파매개물은 피부 보습효과, 피부 유연작용의 피부 건강측면과 피부-탐촉소자간의 피부 윤활성면에서 효과적인 제형임을 알 수 있었다.

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Degradation Assessment of Thermoplastic Synthetic Resin Using Propagation Characteristics of Ultrasound (초음파 전파특성을 이용한 열가소성 합성수지의 열화 평가)

  • Jeon, Woo-Sang;Kim, Gi-Jin;Kwon, Sung-Duk
    • Journal of the Korean Society for Nondestructive Testing
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    • v.34 no.2
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    • pp.141-147
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    • 2014
  • A nondestructive ultrasonic technique was applied to evaluate the thermal characteristics and degradation of synthetic polymer resin (plastics) with better cost-effectiveness and functionality than glass and metal. Thermoplastic and transparent acrylic resin (PMMA) specimens were annealed at below the glass transition temperature ($T_g$), and the propagation characteristics (attenuation and velocity) were measured. The attenuation increased and the velocity decreased with thermal degradation. The results showed that the thermal aging of the specimens could be evaluated quantitatively and that the Tg could be evaluated qualitatively.

Effects of the Equivalence Ratio on Propagation Characteristics of CH4-Air Premixed Flame Intervened by an Ultrasonic Standing Wave (정상초음파가 개재하는 CH4-Air 예혼합화염의 전파특성에 대한 당량비의 영향)

  • Seo, Hang Seok;Lee, Sang Shin;Kim, Jeong Soo
    • Journal of the Korean Society of Propulsion Engineers
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    • v.17 no.2
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    • pp.16-23
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    • 2013
  • An experimental study has been conducted to investigate the effects of equivalence ratio on the propagation characteristics of $CH_4$-air premixed flame intervened by an ultrasonic standing wave. A Schlieren photography was used for the flame structure visualization, and the flame propagation behavior was investigated in detail throughout the post-processing analysis. It is found that the structural variation of methane/air premixed flame caused by the intervention of ultrasonic standing wave give rise to the enhancement of combustion reaction and flame propagation velocity. Effectiveness of the standing wave on the flame velocity decreases as the equivalence ratio increases. Larger flame velocity with the standing wave becomes undistinguishable in a specific range of equivalence ratios.

A Method for Noninvasive Diagnosis of Bone using Ultrasonic Doppler Method (초음파 Doppler법에 의한 생체 경조직의 비침투적인 진단을 위한 기초실험)

  • 박무훈
    • The Journal of the Acoustical Society of Korea
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    • v.17 no.7
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    • pp.3-11
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    • 1998
  • 본 논문에서는 분포정수선로의 간단한 모델을 이용해서, 외부에서 진동을 가했을 때 에 뼈 표면에서 발생하는 굴곡파의 전파속도와 종파의 전파속도를 구할 수 있는 새로운 측 정원리를 제안했다. 이 측정원리를 이용해서, 봉(brass, polymethylmethacrylate)표면에 발생 하는 정재파에 대한 속도의 공간분포를 laser Doppler법으로 측정해서, 각각의 주파수에 대 한 전파속도를 구했다. 이 새로운 측정방법은 in vivo에서 초음파 Doppler법을 이용해서 뼈 의 이상(골다공증, osteoporosis)진단의 가능성을 제시했다.

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Determination of the Effective Elastic Constants of a Superlattice Film by Measuring SAW Velocities (표면탄성파 전파속도 측정에 의한 초격자 다층박막의 유효탄성계수 결정)

  • 김진오
    • The Journal of the Acoustical Society of Korea
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    • v.19 no.5
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    • pp.41-45
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    • 2000
  • The effective elastic constants of a single-crystal superlattice film have been determined by two methods based on the velocities of surface acoustic waves (SAW). One method uses formulas to calculate the effective elastic constants of a superlattice from the known elastic constants of the constituent layers. The calculated effective elastic constants are tested by comparing the corresponding SAW velocities calculated for thin-film/substrate systems with the corresponding SAW velocities measured by line-focus acoustic microscopy (LFAM). The other method determines the effective elastic constants of the superlattices by inverting the SAW velocity dispersion data measured by LFAM. The results of both methods applied to a TiN/NbN superlattice film are in good agreement.

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Interacting Effects of an Ultrasonic Standing-wave on the Propagation Behavior and Structural Stabilization of Propane/Air Premixed Flame (프로판/공기 예혼합화염의 전파거동 및 구조안정화에 대한 정상초음파의 간섭효과)

  • Lee, Sang Shin;Seo, Hang Seok;Kim, Jeong Soo
    • Journal of the Korean Society of Propulsion Engineers
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    • v.16 no.6
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    • pp.1-8
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    • 2012
  • An experimental study has been conducted to scrutinize into the influence of ultrasonic standing wave on the propagating behavior and structural stabilization of propane/air premixed flame at various equivalence ratios in half-open rectangular duct. Evolutionary features of the flame fronts are caught by high-speed images, and the variation of flame structure and local flame velocities along the propagation are analyzed. It is revealed that the propagation velocity agitated by the ultrasonic standing wave is greater than that without the agitation: the velocity enhancement diminishes as the equivalence ratio approaches the stoichiometric. Influence of standing wave on the flame overwhelms that of the buoyancy which slants the flame front towards top of the duct, and thus the standing wave contributes to the structural stabilization of propane/air premixed flame.

A Study on Nondestructive Technique Using Laser Technique for Evaluation of Carbon fiber Reinforced Plastic (레이저를 이용한 탄소섬유강화 복합재료의 비파괴평가 기법에 관한 연구)

  • Choi, Sang-Woo;Lee, Joon-Hyun;Byun, Joon-Hyung;Seo, Kyeong-Cheol
    • Journal of the Korean Society for Nondestructive Testing
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    • v.25 no.2
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    • pp.103-109
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    • 2005
  • Fiber reinforced plastic material should be inspected in fabrication process in order to enhance quality by prevent defects such as delamination and void. Generally, ultrasonic technique is widely used to evaluate FRP. In conventional ultrasonic techniques, transducer should be contacted on FRP. However, conventional contacting method could not be applied in fabrication process and novel non-contact evaluating technique was required. Laser-based ultrasonic technique was tried to evaluate CFRP plate. Laser-based ultrasonic waves propagated on CFRP were received with various transducers such as accelerometer and AE sensor in order to evaluate the properties of waves due to the variation of frequency. Velocities of laser-based ultrasonic waves were evaluated for various fiber orientation. In addition, laser interferometry was used to receive ultrasonic wave in CFRP and frequency was analysed.

Nondestructive testing by using guided wave techniques (유도초음파를 이용한 비파괴탐상 기법)

  • Shin, Hyeon-Jae
    • Journal of the Korean Society for Nondestructive Testing
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    • v.20 no.3
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    • pp.238-245
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    • 2000
  • 유도초음파를 이용하면 배관 및 박판과 같은 파유도체에 대한 광범위한 비파괴탐상을 할 수 있게되어 시간과 경비를 절약할 수 있는 장점이 있다. 그래서 유도초음파를 이해하고 활용하기 위한 연구가 활발히 진행되고 있다. 유도초음파가 기존의 체적 초음파와 크게 다른 점은 분산성있어 초음파의 전파속도가 진동수와 파유도체의 두께에 의존한다는 것과 전파 특성이 다른 무한개의 모드가 존재한다는 것이다. 본 논문에서는 박판과 배관에서의 유도초음파를 이해하고 비파괴탐상에 적용하기 위해 필요한 모드의 분산과 선택 그리고 확인에 대해 이론적인 결과와 및 실험적인 예를 제시하여 그 개념을 소개하였다.

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Modulus and Damping Properties of Kaolinite Using Ultrasonic Testing (초음파를 이용한 카올린 점토의 계수 및 감쇠 특성)

  • 민덕기
    • Journal of the Korean Geotechnical Society
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    • v.18 no.6
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    • pp.17-24
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    • 2002
  • The objective of the present research is to evaluate the wave propagation velocity and attenuation characteristics of kaolin clay specimens using ultrasonic testing. Test specimens with known initial micro-fabric were prepared using a two-stage slurry consolidation technique. For a known state of stress conditions, initial void ratio, and micro-fabric, a series of experiments were conducted to evaluate the longitudinal wave propagation velocity and associated damping behavior. The effects of major variables involved in ultrasonic testing of cohesive soil were considered in this study. Ultrasonic velocity was not correlated to the microfabric structure under the given consolidated pressure whereas ultrasonic attenuation was affected by the microstructural properties of the specimen.

Research on the Effectiveness of Diagnostic Ultrasound Transmission Media (초음파진단 시 전파매질의 유용성)

  • Lee, Hye-Nam
    • The Journal of the Korea Contents Association
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    • v.15 no.1
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    • pp.324-330
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    • 2015
  • When diagnostic ultrasounds are used, an ultrasonic transmission media is used to effectively transmit the ultrasonic energy. Types of ingredients of polymer hydro gel, emulsion, and oil gel were compared with commercialized products by measuring characteristics of ultrasonic transmission media such as skin lubricity, skin moisturizing, and dryness speed which were contained in each different media. The mean friction coefficient measured to investigate skin lubricity showed high in the agent containing a large amount of oil, whereas the mean friction coefficient of the low viscosity emulsion did not show a significant difference with that of the polymer hydro gel. The moisture evaporation measured to investigate the dryness speed of the agent showed highest in polymer hydro gel. This showed that the larger amount of oil it had, the less moisture evaporation occurred. For skin moisture measured to investigate moisturizing characteristics of skin, low viscosity emulsion showed high in moisture content, whereas it showed slowest reduction in moisture content. As a type of emulsion appropriately containing water and oil is superior in skin moisturizing and skin tenderness, it is expected to serve as a dosage form of new ultrasonic transmission media.