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김봉영(BongYoung Kim),배명진(MyungJin Bae) 인문사회과학기술융합학회 2018 예술인문사회융합멀티미디어논문지 Vol.8 No.5
통조림은 우리 식생활에서 빼놓을 수 없는 대표적인 식품 중 하나이다. 통조림은 제조과정의 특성상 일정 수준 이상의 진공도를 갖게 되어 독특한 소리특성을 갖게 된다. 통조림의 독특한 소리특성을 이용한 타관검사를 통해 검사원의 청각과 촉각으로 불량품을 판별할 수 있다. 그러나 타관검사는 검사원의 상태에 따라 정상여부의 판별 결과가 달라질 수 있다. 통조림의 상태에 따른 소리성분을 구분해 낼 수 있다면 통조림에 대한 불량품 판별이 더욱 용이해 질 것이다. 본 논문에서는 통조림을 두드리는 실험을 통해 각 상태별 소리성분을 비교분석하여 정상제품과 불량제품을 구분할 수 있는지 확인하고자 한다. 실험결과 정상제품은 1900Hz에서 주로 공명하고 잔향시간이 짧은 반면, 외형변형 제품의 경우 여러 주파수에서 복잡하게 공명하고, 부패된 제품에서는 800Hz의 낮은 주파수에서 공명하면서 잔향시간이 매우 길었다. 용량이 미달되는 제품은 정상제품에 비해 매우 높은 3100Hz에서 공명하였다. 이러한 실험결과로 소리분석을 통해 불량 통조림을 판별할 수 있음을 확인하였다. Canned Goods is one of the most important foods in our diet. Canned goods have peculiar sound characteristics because they have a degree of vacuum above a certain level due to the nature of the manufacturing process. Percussion inspection using the peculiar sound characteristics of Canned Goods allows the inspector to detection of defective products with hearing and tactile senses. However, the percussion inspection can be different from the result of discrimination, due to the condition of the inspectors. If we can distinguish the sound components according to the condition of the Canned Goods, it will be easier to detection of defective products for the Canned Goods. In this paper, we try to compare the sound components of each state by percussion experimen with Canned Goods to see if it is possible to distinguish between normal and defective products. Experimental results show that the normal product resonates mainly at 1900Hz and has a short reverberation time. However, the distorted product has complicated resonance at various frequencies, and the corrupt product has a long reverberation time while resonating at a low frequency of 800Hz. Products with less capacity resonated at 3100 Hz, which is much higher than normal products. As a result of these experiments, we confirmed that we can distinguish bad Canned Goods through sound analysis.
안봉영(Bongyoung Ahn),조승현(Seung Hyun Cho),김영주(Young Joo Kim),김기복(Ki-Bok Kim) 한국비파괴검사학회 2010 한국비파괴검사학회지 Vol.30 No.4
EMAT는 비접촉식 탐촉자인 동시에 모드 선택성이 우수하여 다양한 분야에 적용되고 있으나 근본적으로 에너지 전환효율이 낮아 신호 대 잡음비의 증가에 한계를 보인다. EMAT에 위상배열 기술을 접목하면 초음파의 집속 효과를 얻을 수 있으므로 낮은 전환효율의 문제를 극복하기 위한 하나의 해결방안이 될 수 있을 것으로 판단한다. 본 연구에서는 위상배열 EMAT에 대한 기초연구로 3~4개의 코일로 구성되는 표면파 및 수직횡파 발생용 위상배열 EMAT를 제작하고 각 요소코일에 공급하는 펄스의 지연으로부터 위상배열의 효과를 확인하고 방향특성을 측정하였다. 또한 시험편의 표면에 0.5 mm 깊이의 표면결함과 시험편 내부에 직경 0.5 mm의 측면 드릴 홀을 가공하여 제작된 위상배열 EMAT로 결함 신호를 검출하였으며, 이로부터 제작된 EMAT의 성능을 평가하였다. EMAT has been applied in various fields for flaw detection and material characterization because it has noncontact property in wave generation and a good mode selectivity. Unfortunately, however, EMAT shows low signal to noise ratio relative to commercial contact transducer because of low energy conversion efficiency. If the phase matching through the control of time delay between each coil consisting of the array EMAT is accomplished, it is expected that it will be a solution for the improvement of low signal to noise ratio. In this experiment, the phased array EMATs which consists of 3 or 4 meander coils and one big magnet were fabricated for surface and vertical shear wave generation. Effect of phased delay control on signal directivity and amplitude enhancement was verified. A slit with the depth of 0.5 mm and a side-drill hole of 0.5 mm diameter were clearly detected by fabricated phased array EMATs, respectively.
김기복(Ki-Bok Kim),안봉영(Bongyoung Ahn),박해원(Haewon Park),김영주(Young-ju Kim),이승석(Seung-Seok Lee) 대한기계학회 2004 대한기계학회 춘추학술대회 Vol.2004 No.8
In this study, the capacitive micromachined ultrasonic transducer (cMUT) was developed. Theoretical analysis and finite element analysis of the behavior of membrane (such as resonance frequency, membrane deflection, collapse deflection and collapse voltage) of the cMUT were performed. The design parameters of the cMUT were estimated and are the dimension and thickness of membrane, thickness of sacrificial layer, thickness and size of electrode, size of active element and so on. With the micro-fabrication process, the cMUT was fabricated on the silicon wafer. To measure the membrane displacement of cMUT, the Michelson phase modulation fiber interferometer was constructed. The measured membrane displacement was good agreed with the result of finite element analysis. To estimate the ultrasonic wave generated by the cMUT, the ultrasonic transceiver system was constructed. The developed cMUT shows a good performance and hence will be widely used to the filed of non-contact ultrasonic application.
다발성 골수종 환자에서 발생한 Bacteroides thetaiotaomicron 화농성 관절염
노민호 ( Minho Noh ),김봉영 ( Bongyoung Kim ),김지은 ( Jieun Kim ),최현주 ( Hyunjoo Choi ),염준기 ( Junki Yeom ),정태양 ( Taeyang Jung ),배현주 ( Hyunjoo Pai ) 대한내과학회 2017 대한내과학회지 Vol.92 No.1
Septic arthritis is rarely caused by anaerobic bacteria, which is mostly secondary to hematogenous dissemination among the immunocompromised host. We report a patient of septic arthritis on the right knee joint caused by Bacteroides thetaiotaomicron. To the best of knowledge, this is the first report of septic arthritis caused by Bacteroides spp. in Korea. (Korean J Med 2017;92:99-102)
미세채널 내 정재초음파 장 형성 및 미세입자 거동 관찰
조승현(Seung Hyun Cho),서대철(Dae-Cheol Seo),안봉영(Bongyoung Ahn),김기복(Ki-Bok Kim),김용일(Yong-Il Kim) 대한기계학회 2008 대한기계학회 춘추학술대회 Vol.2008 No.5
Using ultrasonic standing waves, the position of micro particles submerged or flowing in fluid can be manipulated. Due to the acoustic radiation force of ultra sounds, particles are forced to move to pressure nodes or antinodes of standing wave field. In this work, ultrasonic standing wave field was generated in a micro water channel of a few millimeter width and the behavior of the submerged particles was observed. The standing wave field generation system was established using an immersible ultrasonic transducer. The system is valid in a frequency range between 2.0 ㎒ and 2.5 ㎒. Particles in consideration were SiC powder of a few micrometer diameters. It was observed that the particle in water moves to pressure nodal lines in the standing field. The effect of the channel thickness and operating frequency on the particle behavior was also investigated.