• 제목/요약/키워드: Echo level

검색결과 144건 처리시간 0.023초

저서어자원량의 음향추정에 있어서 해저기준과 해저 오프셋의 최소화 (Stable Bottom Detection and Optimum Bottom Offset for Echo Integration of Demersal Fish)

  • 황두진
    • 수산해양기술연구
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    • 제36권3호
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    • pp.195-201
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    • 2000
  • 계량어군탐지기를 이용하여 저서어를 대상으로 에코적분을 행하는 경우, 적분범위의 하한을 결정하기 위해 설정하는 해저기준이나 해저오프셋은, 저서어 자원량추정의 중요한 요인 중의 하나이다. 해저부근의 어군에코의 해석으로부터 해저기준의 결정방법과 최적 오프셋에 관하여 고찰한 결과, 다음과 같은 결과를 보였다. 1) 적분층의 폭을 5m로 하여, 적분범위를 1샘플링씩 해저방향으로 이동하면서, 해저부근의 S$\sub$a5m/의 변화를 본 결과, 해저부근의 어군에코를 적분하기 위해서는, 적분범위의 하한을 가능한 해저까지 접근시켜야 한다. 2) 에코레벨의 역치로서 해저검출을 행한 경우, 역치가 클수록 해저 검출 불능횟수가 증가하고, 작을수록 해저 오검출 횟수가 늘어 났다. 3) 에코레벨의 최대변화점을 해저기준으로 한 해저검출법은, 그 정도가 매우 높았으며, 나아가 에코레벨의 변동에 대해 아주 안정한 해저기준 알고리 즘으로 적합하였다. 4) 이 해저검출 알고리즘에 의하면, 최적해저오프셋은 해저 기준으로부터 0.4ms이내였고, 이것은 펄스파형과 해저지형에 대한 음향빔에 의존한다.

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동지나해의 초음파 산란층에 관한 연구 ( 1 ) ( Acoustic Scattering Layers in the East China Sea ( 1 ) )

  • 이대재;신형일;박중희
    • 수산해양기술연구
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    • 제26권1호
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    • pp.14-19
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    • 1990
  • 동지나해의 초음파산란층에 대한 기초적 연구로서, 산란층의 주야간에 대한 수직이동상태와 Echo 신호의 변동특성에 관하여 검토한 결과, 수심 20m~80m에 형성된 상\ulcorner하한의 수온차가 약 11$^{\circ}C$인 수온약층부에서 일몰 전에는 산란층의 Echo 신호가 뚜렷하지 않았으나, 일몰 후부터 수심 35m~45m 구간에서 산란층이 강하게 나타내기 시작하여, 시간이 경과할수록 수직적으로 신장되면서 표층을 향해 점차 부상하는 경향을 나타내었다. 한편, 일출 전에 초음파산란층의 상부는 수온약층의 상부까지 부상하였고, 또 전 수심에서 상당히 강한 Echo 신호가 돌발적으로 출현하는 현상이 확인되었으며, 이것은 저층에 분포하고 있던 어군이 부상하여 발생한 것으로 생각된다. 일출 후에는 산란층이 급속히 하강함과 동시에 Echo level도 급격히 낮아지는 경향을 나타내었고, 그 하강속도는 일몰 후 산란층의 부상속도에 비해 현저하게 빠른 현상을 나타내었으며, 일출전후 약 30분간에 가장 강한 Echo 신호가 관측되었다. 또 Echo 신호의 진폭빈도분포는 일몰전에는 전 수층에 걸쳐 Echo level이 매우 낮으므로 낮은 level에 많이 집중되는 지수분포형을 나타내고, 일출전후에는 Echo 신호가 높은 level에 많이 집중되는 정규분포형을 나타내었다.

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Sociodemographic and Health Related Factors Influencing Problem Drinking of the Echo Generation Using Data of the 2018 Korean National Health and Nutrition Examination Survey

  • Kwak, Minyeong
    • International Journal of Contents
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    • 제17권1호
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    • pp.54-60
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    • 2021
  • The aim of this study was to identify factors influencing problem drinking among the Echo Generation in South Korea and provide basic data for early intervention and mediation of problem drinking among the Echo Generation. This descriptive study performed a secondary analysis of raw data from the 2018 Korean National Health and Nutrition Examination Survey and used responses for problem drinking items from 999 Echo Generation participants born between 1979 and 1992. This study comprehensively investigated sociodemographic and health-related factors influencing problem drinking among the Echo Generation. SPSS WIN program (version 26.0) was used for data analysis. Gender (β=-.32, p<.001), education level (β=.10, p=.002), white-collar workers out of job (β=-.09, p=.041), and depression (β=.11, p<.001) were identified as factors that influenced problem drinking among the Echo Generation. Results of this study suggest that in order to prevent problem drinking among the Echo Generation, there should be user-customized prevention education and intervention programs.

에코부머의 근로빈곤에 관한 연구 (A Study on the Working Poor among Korean Echo Boomers)

  • 박미석;박미려
    • Human Ecology Research
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    • 제52권1호
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    • pp.87-101
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    • 2014
  • The purpose of this study is to identify the current status of the working poor and the factors that are influential to the working poor among echo boomers. This study is a secondary analysis using the data from the 7th analysis of the 2012 Korea Welfare Panel Survey, conducted by Korea Institute for Health and Social Affairs. This analysis considered Korean echo boomers born between 1979 and 1985. In our final analysis, we used 1,226 echo boomers who had the ability to work. For the analysis, the SAS/PC statistical program ver. 9.3 was utilized. The research findings are as follows; Firstly, of the working poor among the echo boomers, only 22% were in the state of poverty. Secondly, more echo boomers living in a metropolitan city, city, gun/urban-rural area and district than those in the Seoul were categorized as among the working poor; the same was true for those who lived in a free house than in a leased room or a room that was rented by the month. Thirdly, more echo boomers whose education level was high school graduate or less rather than college graduate or less or university graduate or more were categorized as among the working poor; this was also true for echo boomers whose employment type was temporary employment, self-employment, or unemployment rather than a full-time job.

Level Limit스위치용 1-3형 복합압전체 트랜스듀서의 펄스-에코응답특성 (Pulse-echo Response of Piezoceramic-Polymer 1-3 Type Composite Transducer for a Level Limit Switch Applications)

  • 최헌일;손무헌;김홍근;박경일;사공건
    • 한국전기전자재료학회:학술대회논문집
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    • 한국전기전자재료학회 2002년도 춘계합동학술대회 논문집
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    • pp.224-228
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    • 2002
  • In this study, the piezoelectric ceramics PZT powder was synthesized by the Wet-Dry combination method. Flexible 1-3 type composite specimens were fabricated with the piezoceramics PZT filler phase and Eccogel polymer matrix phase. This paper represents the pulse-echo response of the 1-3 type composite transducer to check it out to investigate a basic property regarding a level limit switch. The acoustic impedance of 1-3 type composite was improved than that of single phase PZT ceramics. The pulse-echo response of transducer fabricated with the self-made 1-3 type composites resonator was better than that of the solid PZT transducer.

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한국 황해 백령도 주변해역 후 제4기 퇴적작용 (Late Quaternary Sedimentation in the Yellow Sea off Baegryeong Island, Korea)

  • 조민희;이은일;유학렬;강년건;유동근
    • 지구물리와물리탐사
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    • 제16권3호
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    • pp.145-153
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    • 2013
  • 황해 백령도 주변해역에 분포하는 해저면 연계퇴적층의 음향상 연구를 위해 고해상 탄성파 탐사자료를 분석하였다. 해저지형 및 내부 음향상 특징에 의하면 연구지역에 분포하는 천부퇴적층은 총 7개의 음향상으로 구분된다. 내부 반사면이 약간 혹은 양호하게 발달하거나 내부반사면을 전혀 수반하지 않는 평탄한 해저면(음향상 1-1, 1-2)은 연구지역의 남쪽에 주로 분포한다. 파형의 표면구조를 수반하는 평탄한 해저면(음향상 1-3)은 중부해역에 발달한다. 평탄한 해저면 혹은 파형의 표면구조를 수반하는 마운드 형태의 해저면 특징(음향상 2-1, 2-2, 2-3)은 중부해역에 분포한다. 내부 반사면이 발달하지 않고 불규칙한 침식흔적을 갖는 해저면(음향상 3-1)은 조사해역의 북부해역인 백령도 외해쪽에 주로 존재한다. 음향상의 분포 및 퇴적물 특성에 의하면 연구지역의 퇴적환경은 뚜렷한 3 지역으로 구분되는 바 (1) 강한 조류의 영향으로 심한 침식작용이 진행되고 있는 북쪽지역, (2) 해수면 상승과 연계된 조류의 영향으로 형성된 사퇴가 분포하는 중부해역, (3) 박층의 해침 사질층이 분포하고 있는 남부해역 등으로 구성된다. 연구지역에 분포하는 7 음향상을 포함하는 이와 같은 퇴적층은 홀로세 해침동안 해수면 상승 및 강한 조류와 연계된 퇴적작용을 반영한다.

부비동염의 초음파 진단법에 관한 임상연구 (A Clinical Study on the Ultrasonographic Diagnosis of Sinusitis)

  • 조재훈;이승은;한은정;김찬중;김윤범
    • 대한한의학회지
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    • 제23권2호
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    • pp.88-96
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    • 2002
  • Objective : This study attempted to evaluate the ultrasonographic diagnosis of sinusitis compared to X-ray diagnosis and further to help the diagnosis and treatment of sinusitis through oriental medicine. Methods : Both A-mode ultrasonography and X-ray were taken of 30 symptom-positive patients and 10 symptom-negative controls. Nasal obstruction, rhinorrhea, postnasal drip, headache (facial pain), hyposmia (anosmia), throat discomfort and chronic cough were included in the symptoms of sinusitis. Both ultrasonographic and X-ray findings were divided into four groups (clear, mucosal thickening, air-fluid level and cystic shape) according to severity. Results : 1. The symptoms of patients (n=30) were as follows: nasal obstruction (83.3%), rhinorrhea (70.0%), postnasal drip (60.0%), chronic cough (53.3%), headache (40.0%), throat discomfort (40.0%), hyposmia (26.7%). 2. There was a significant correlation between symptoms and ultrasonographic findings (n=40, ${\gamma}=0.550$, P=0.001). 3. There was a significant correlation between symptoms and X-ray findings (n=40, ${\gamma}=0.555$, P=0.001). 4. There was a significant whole coincidence between ultrasonographic and X-ray findings (n=60, ${\gamma}=0.335, P=0.00l). Moreover, there was a significant coincidental trend between the two findings as they became severe (n=60, ${\gamma}=6.284$, P=0.012). 5. The distance of the ultrasonographic echoes was as follows: clear echo (n=9, from transducer pulse to air mucosa echo) $0.90{\pm}0.19cm$, mucosal thickening echo (n=23, from transducer pulse to air mucosa echo) 1.85{\pm}0.14cm, air-fluid level echo (n=26, from transducer pulse to back wall echo) $3.70{\pm}0.16cm$. 6. The highest diagnostic reliability of the ultrasonographic findings compared to X-ray findings was as follows: over-diagnosis in clear finding 77.3%, matched diagnosis in mucosal thickening finding 62.0%, matched diagnosis in air-fluid level finding 86.7%, matched diagnosis and under-diagnosis in cystic shape finding 50.0%. 7. In mucosal thickening, air-fluid level and cystic shape finding, there was a significant individual coincidence between the ultrasonographic and X-ray findings. In clear finding, there was no significant individual coincidence between the two findings. Conclusion : The ultrasonographic diagnosis significantly reflects the symptoms of sinusitis like X-ray diagnosis and is a valuable tool to screen prognostic factors such as mucosal thickening, air-fluid level and cyst. Therefore the ultrasonography will be useful for the diagnosis and treatment of sinusitis in oriental medicine.

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Ultrasonographic evaluation of rotator cuff leison

  • Sugimoto Katsumasa;Matsui Nobuo
    • 대한견주관절학회:학술대회논문집
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    • 대한견주관절학회 1995년도 Symposium and Workshop
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    • pp.46-46
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    • 1995
  • We investigated the reliablity of the ultrasonography for diagnosis of rotatar cuff taers. We prepared histological sections of forty shoulder joints In match the ultrasound planes, and conducted a comparative study of tke two sets of images. hi cases of rotator cuff tear, hyperechogenic and cartilaginfication of the tear site were detected as hyperechogenic foci. On the countrary, the regions in which tendon fibers were decreased or absent showed sonolucent areas. We caluculated the echo level of rotator cuff objectively. The area of abnormal echo level and the other regions located in the same depth of the rotator cuff were defined by ultrasonic equipment. The mein difference in these two echo levels was calculated. The mean difference in patients with rotator cuff tears was larger than that in normal cases. These results indicate that ultrasonography is a useful procedure in many patients with rotator cuff lesions.

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Accuracy Enhancement of Reflection Signals in Impact Echo Test

  • Lho, Byeong-Cheol
    • 콘크리트학회논문집
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    • 제15권6호
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    • pp.924-929
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    • 2003
  • A majority of infrastructures has been deteriorated over time. Therefore, it is very important to verify the quality of construction, and the level of structural deterioration in existing structures, to ensure their safety and functionality. Many researchers have studied non-destructive testing (NDT) methods to identify structural problems in existing structures. The impact echo technique is one of the widely used NDT techniques. The impact echo technique has several inherent problems, including the difficulties in P-wave velocity evaluation due to inhomogeneous concrete properties, deterioration of evaluation accuracy where multiple reflection boundaries exist, and the influence of the receiver location in evaluating the thickness of the tested structures. Therefore, the objective of this paper is to propose an enhanced impact echo technique that can reduce the aforementioned problems and develop a Virtual Instrument for the application via a thickness evaluation technique which has same technical background to find deterioration in concrete structures. In the proposed impact echo technique, transfer function from dual channel system analysis is used, and coherence is improved to achieve reliable data. Also an averaged signal -ensemble- is used to achieve more reliable results. From the analysis of transfer function, the thickness is effectively identified.

TMS320C31 DSP를 이용한 음향반향제거기의 실시간 구현 (Real-Time Implementation of an Acoustic Echo Canceller Using TMS320C31 DSP)

  • 장병욱;김시호;권홍석;배건성
    • 음성과학
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    • 제9권3호
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    • pp.17-24
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    • 2002
  • The goal of this research is the real-time implementation of an AEC (Acoustic Echo Canceller) using the floating-point digital signal processor of TMS320C31. We employ an FIR-type adaptive filter with the conventional NLMS (Normalized Least Mean Square) algorithm for the adaptation of filter coefficients. We program and optimize the system in the assembler level to make it run in real-time. With 8 kHz sampling rate, the implemented AEC requires $46\;\mu$sec and $77\;\mu$sec computational time per sample for 128-and 256-tap filter, respectively. It corresponds to 37% and 62% of maximum computational ability of TMS320C31 DSP.

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