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김봉기(Kim, Bong-Ki),김상렬(Kim, Sang-Ryul),김현실(Kim, Hyun-Sil),신민철(Shin, Min-Chol) 한국소음진동공학회 2008 한국소음진동공학회 논문집 Vol.18 No.12
A muffler design in the exhaust system is critical to provide fur low noise in shipboard spaces. In an attempt to effectively design the low noise muffler, it Is important to evaluate the performance of the muffler considering not only the noise, but also pressure drop as well. For this purpose, a test system of large exhaust mufflers fur ship propulsion systems was designed based on ISO 7235. The substitution test fur determining both the insertion loss and pressure drop of mufflers was carried out. A ship exhaust muffler is considered as a test example and the insertion loss and pressure drop were obtained.
김현실,김봉기,김상렬,이성현,Kim, Hyun-Sil,Kim, Bong-Ki,Kim, Sang-Ryul,Lee, Seong-Hyun 한국음향학회 2015 韓國音響學會誌 Vol.34 No.3
본 논문은 단면이 정사각형인 임피던스 튜브 내에 고정된 평판의 STL(Sound Transmission Loss)을 해석적으로 구하는 방법을 다루었다. 평판의 진동과 튜브 내의 음장의 연성거동(coupled motion)을 고려하였는데 평판의 진동과 튜브 음장을 무한 급수의 합으로 전개하였으며 평면파 가정을 이용하여 처음 몇 개의 모드만 고려하여도 충분히 정확한 결과를 얻음을 보였다. 평판은 클램프(clamp) 지지로 가정하였는데 진동 모드는 단면의 가로 및 세로방향 보(beam) 진동 모드의 곱으로 전개하였고 고유진동수는 Rayleigh-Ritz 방법을 이용하여 구하였다. 평판의 STL은 가장 낮은 고유진동수에서 골(dip)을 가지며 주파수가 이보다 작아지면 STL은 커짐을 보였다. 기존 논문의 측정 및 FEM(Finite Element Method) 해석결과와 비교한 결과 잘 일치함을 확인하였다. In this paper, derivation of the STL (Sound Transmission Loss) of a square plate installed in an impedance tube is discussed using an analytic method. Coupled motion of the plate vibration and acoustic field is considered. Vibration of the plate and pressure field inside the tube are expressed in terms of the infinite series of modal functions. Under the plane wave assumption, it is shown that consideration of the first few modes yields sufficiently accurate results. When the boundary of the plate is clamped, vibration mode is assumed as a multiplication of the beam modes corresponding to the crosswise directions. The natural frequencies of the clamped plate are calculated using the Rayleigh-Ritz method. It is found that the STL shows a dip at the lowest natural frequency of the plate, and increases as the frequency decreases below the natural frequency. Comparison of the result in this paper with the STL obtained by measurements and FE computations in the reference shows an excellent agreement.
김현실(Hyun Sil Kim),김남희(Nam Hee Kim),육종인(Jong In Yook),김진(Jin Kim),박혁(Hyok Park),차인호(In Ho Cha) 대한구강악안면병리학회 2010 대한구강악안면병리학회지 Vol.34 No.6
Osteogenic sarcoma is primary malignant bone tumor. It can arise de novo or from the benign precursors lesions, like Paget's disease, giant cell tumor, chronic osteomyelitis, osteoblastoma, and fibrous dysplasia. Here, we present a case of osteogenic sarcoma arising from florid osseous dysplasia appearing as a rapidly growing bony bulging mass in 44-year-old Korean female who had at first been non-symptomatic, but later suffered from the numbness of chin and lower lip. The radiologic images revealed the mixed radiopaque- radiolucent intraosseous lesions throughout the mandible, which were diagnosed as florid osseous dysplasia pathologically. But only after 6 months, the lesions were substituted by the radiological ill-defined diffuse bony sclerotic lesion with bone destruction, accompanying the interrupted periosteal bone formation, which were pathologically diagnosed as osteogenic sarcomas. These serial clinicopathologic changes imply the malignant progression of florid osseous dysplasia rather than the collision of benign condition, florid osseous dysplasia and malignant tumor, osteogenic sarcoma. The possibility for fibro-osseous lesion of the jaw as premalignant lesion should not be overlooked; therefore, periodic check-ups for the lesions are necessary. Proper evaluation and interpretation for clinical neural symptom and radiologic change of bone density may lead to the correct differential diagnosis and therapeutic intervention.