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Pekeris 도파관에서 음선 접근법을 이용한 지면파 해석
최지웅,Choi, Jee-Woong 한국음향학회 2009 韓國音響學會誌 Vol.28 No.3
지면파는 해저면 음속이 깊이에 따라 일정할 경우 해저면 음속으로 진행하는 음파로 일반적으로 모드분산으로부터 설명된다. 모드분산은 도파관의 기하학적 구조에 의한 음파의 반사 및 굴절에 의해 발생되므로 본 논문에서는 지면파를 음선이론에 기초하여 모의하였다. 지면파는 일련의 선두파들의 조합으로써 해석될 수 있으므로 [Choi와 Dahl, J. Acoust. Soc. Am. 119, 3660-3668 (2006)], 음선 접근법을 이용하여 시간영역에서 여러 경로로 전파되는 선두파들의 채널 임펄스 응답과 선두파 신호의 컨볼루션을 취하여 지면파를 모의한다. 모의된 지면파는 광대역 시간영역 포물선 방정식 기법을 이용하여 모의된 지면파와 비교, 검증된다. Ground wave is an acoustic wave propagating at a sediment sound speed in the case that sediment sound speed is constant with depth, which is explained by modal dispersion effects. In this paper, the ground wave in time domain is simulated using the ray-based approach, which is possible because the modal dispersion can be explained by the guiding of energy caused by reflection and refraction in the waveguide geometry. For a Pekeris waveguide, the ground wave can be interpreted as a sequence of head waves, called a head wave sequence [Choi and Dahl, J. Acoust. Soc. Am. 119, 3660-3668 (2006)]. The ground wave is simulated by convolution of the source signal with a channel impulse response of the head wave sequence, which is compared with simulated signals obtained via a Fourier synthesis of a complex parabolic equation (PE) field.
최지웅 ( Jeewoong Choi ),박소영 ( So Young Park ),문경태 ( Kyong Tae Moon ),이원미 ( Won Mi Lee ),이병훈 ( Byoung-hoon Lee ),김상훈 ( Sang-hoon Kim ) 대한천식알레르기학회(구 대한알레르기학회) 2021 Allergy Asthma & Respiratory Disease Vol.9 No.1
Nonepisodic angioedema with eosinophilia (NEAE) is a rare disease characterized by nonrecurrent angioedema with eosinophilia and normal serum IgM levels occurring predominantly in an East Asian female population. A 49-year-old male patient visited our clinic due to swelling of both the scrotums and the lower extremities, and fever. He had history of nasal polyp, cephalosporin allergy, and asthma. He was diagnosed as having NEAE and was treated with systemic corticosteroid, then he was symptom-free for more than 8 months. He had been administered omalizumab for 3 months due to uncontrolled asthma prior to the onset of angioedema which had helped taper the oral corticosteroid, and this may be associated with presentation of NEAE. Here, we report a case of NEAE in a male patient which presented with constitutional symptoms such as fever and scrotal edema. (Allergy Asthma Respir Dis 2021;9:46-49)
어도 어류군집 분석 및 다양한 변수를 이용한 어도효율성모델 개발
최지웅 ( Ji-woong Choi ),( Md Mamun ),안광국 ( Kwang-guk An ) 한국환경생태학회 2016 한국환경생태학회 학술대회지 Vol.2016 No.2
The main goal of this study was to develop an multi-metric model of fishway efficiency assessments (FEA) model, which is composed three major components including the structural characteristics, hydraulic/hydrological features and biological attributes metrics. The FEA model was developed for diagnosing and assessing the fishway efficiency and then the model applied to a Juksan-weir of Yeongsan River watershed. The model of FEA was established with nine metrics, which were categorized into structural characteristics of fishway, hydraulic/hydrological features, and the biological characteristics. Overall, the outcomes on the assessments of fishway efficiency showed that total score of the FEA model was 25 in the Juksan-weir, which was indicated as a "good condition" by the criteria of five classification system. The FEA model may be used as a key tool for the assessments of fishway efficiency, especially on 16 weirs constructed for "four major Korean rivers project" after a partial calibration of FEA model.
Forchheimer 포화항력모델을 이용한 투수성 호안의 해수교환량 모의
최지웅 ( Ji-woong Choi ),위현철 ( Hyun-chul Wi ),김대근 ( Dae-geun Kim ) 조선대학교 공학기술연구원 2021 공학기술논문지 Vol.14 No.3
In this study, FLOW-3D's Forchheimer's saturation drag model was used to physically reproduce the flow of infiltrating water in the body of the permeable seawall. This study confirmed that Forchheimer's saturation drag model could be applied to the permeability evaluation of the sea wall. The flow patterns in the body were compared between the temporary seawall constructed using only rubble stones and the back reinforced seawall in which the back part of the seawall was reinforced with filter rocks and mats. The flow patterns in the temporary seawall body were well-reproduced, in which the infiltration water moves from the open sea to the inside, and the flow accelerates as the stream tube shrinks. In the back-reinforced seawall, the flow pattern in which the seepage line of the body rises compared to the temporary seawall is well-reproduced due to the low permeability of the filter mat. When the simulated results of the inland tide surrounded by the seawall were compared with the observation data, the simulated and observed values showed a slight difference within 0.3m. At the T5 point, seawater exchange through the seawall was relatively as large as the temporary seawall installed. The simulation results reproduced the phenomenon that the tidal wave occurred smaller than the T5 point because the seawater exchange rate through the seawall was relatively low at the T6 point. After all, the back-reinforced seawall was smaller. In addition, it reproduced the observation data in which the tide was delayed, and the duration of the ebb tide was superior to that of the flood tide.