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구형 알루미늄 쉘 내부의 충전 유체에 따른 수중 음향 산란 특성 분석 및 유사 위그너-빌 분포를 이용한 식별 기법 연구
추연성,변성훈,김시문,이근화,Choo, Yeon-Seong,Byun, Sung-Hoon,Kim, Sea-Moon,Lee, Keunhwa 한국음향학회 2019 韓國音響學會誌 Vol.38 No.5
The acoustical scattering characteristics of a target are influenced by the material properties and structural characteristics of the target, which are critical information for acoustic detection and identification of underwater target. In particular, for thin elastic target, unique scattered signals are generated around the target by the Lamb wave. In this paper, the results of scattered signal measurement of aluminum spherical shell in the water tank using the stepped frequency sweep sine signal are presented. In particular, the scattering of the water-filled aluminum spherical shell is compared with that of the air-filled one both theoretically and experimentally. The difference of the scattered signals are analyzed using the pseudo Wigner-Ville distribution in terms of average frequency, frequency distribution, and energy of the scattered signal. The result shows that all observed parameters increased when the aluminum sphere was water-filled, and it is well matched to the theoretical expectation. 표적의 음향 산란 특성은 표적의 재료 특성과 구조적 특성에 영향을 받으며, 이는 음향을 이용하여 수중에서 표적을 탐지, 식별하고자 할 때 매우 중요한 정보가 된다. 특히, 얇은 탄성체의 경우 램파(Lamb wave)에 의해 표적 주변 유체에 산란파가 생성된다. 본 논문에서는 계단 주파수 스윕 사인 파형을 이용하여 수조에서 알루미늄 구의 산란 신호를 측정한 결과를 제시한다. 특히 알루미늄 구의 내부에 물이 채워져 있는 경우와 공기가 채워져 있는 경우에 대하여 산란 신호의 차이를 측정하고 이론 모델과 비교하였다. 또, 내부 물질에 따른 표적 산란 신호 차이를 유사 위그널-빌 분포를 이용하여 분석하고, 유도파의 평균 주파수, 주파수 분포, 에너지의 차이를 비교하였다. 분석 결과, 구의 내부에 물이 채워진 경우가 공기가 채워진 경우에 비해 유도파의 평균 주파수, 주파수 분포, 에너지가 증가하는 것을 확인하였으며 이는 이론적인 예상과 부합한다.
양상태 소나에서의 자세각과 양상태각에 따른 표적 식별 정확도 비교
추연성,변성훈,추영민,최기융,Choo, Yeon-Seong,Byun, Sung-Hoon,Choo, Youngmin,Choi, Giyung 한국음향학회 2021 韓國音響學會誌 Vol.40 No.4
In bistatic sonar operation, the scattering strength of a sonar target is characterized by the probe signal frequency, the aspect angle and the bistatic angle. Therefore, the target detection and identification performance of the bistatic sonar may vary depending on how the positions of the target, sound source, and receiver are changed during sonar operation. In this study, it was evaluated which variable is advantageous to change by comparing the target identification performance between the case of changing the aspect angle and the case of changing the bistatic angle during the operation. A scenario of identifying a hollow sphere and a cylinder was assumed, and performance was compared by classifying two targets with a support vector machine and comparing their accuracy using a finite element method-based acoustic scattering simulation. As a result of comparison, using the scattering strength defined by the frequency and the bistatic angle with the aspect angle fixed showed superior average classification accuracy. It means that moving the receiver to change the bistatic angle is more effective than moving the sound source to change the aspect angle for target identification.
Cephalexin Prodrug 연구(I) - Cephalexin Phthalidyl Ester의 Prodrug으로서의 유용성
조윤성,추연성,양중익 대한약학회 1980 약학회지 Vol.24 No.1
In order to increase the gastro-intestinal absorption of cephalexin, a new cephalexin phthalidyl ester was synthetized. Comparative studies of cephalexin phthalidyl ester in the gastro-intestinal absorption were conducted after oral administration in rabbits. The amounts of cephalexin in plasma were determined by a fluorometric method. Cephalexin phthalexin phthalidyl ester could not be identified in plasma, but only cephalexin was found by TLC method. In comparison with cephalexin, cephalexin phthalidyl ester produced much higher plasma levels of cephalexin than did cephalexin itself after its oral administration in rabbits.
시리안 햄스터 볼주머니 점막에 대한 recombinant human Granulocyte Macrophge-Colony Stimulating Factor의 효과
조선아(Sun-A Cho),박종환(Jong-Hwan Park),석승혁(Seung-Hyeok Seok),전재현(Jae-Hyeon Juhn),김성진(Seong-Jin Kim),지희정(Hyi-Jeong Ji),추연성(Youn-Sung Choo),박재학(Jae-Hak Park) 한국실험동물학회 2004 Laboratory Animal Research Vol.20 No.3
This study was aimed to identify the effect of recombinant human Granulocyte Macrophge-Colony Stimulating Factor (rhGM-CSF) on the mucous membrane of hamster cheek pouch. After anesthetized with ketamine and xylazine, hamsters were topically administered with rhGM-CSF at the dose of 0.4 ㎍/㎖, 2㎍/㎖, 10 ㎍/㎖, 50 ㎍/㎖, and 250 ㎍/㎖ for 14 days. The thickness of the sratum basale, stratum spinosum, and stratum corneum was determined in each group. And cell proliferation in mucosal layer was also evaluated by immunohistochemistry. The thickness of stratum spinosum increased in the group administered with rhGM-CSF of 0.4 ㎍/㎖ (1.75㎛±0.69), but decreased in the groups administered with that of over 2 ㎍/㎖. In immunohistochemistry, high Ki-67 positive response was also detected in the hamster administered with rhGM-CSF of 0.4㎍/㎖. This study showed that rhGM-CSF induces the epithelial proliferation at concentration of 0.4㎍/㎖.