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Acoustic performance of industrial mufflers with CAE modeling and simulation
전수홍,김대환,홍진숙,정의봉 대한조선학회 2014 International Journal of Naval Architecture and Oc Vol.6 No.4
This paper investigates the noise transmission performance of industrial mufflers widely used in shipsbased on the CAE modeling and simulation. Since the industrial mufflers have very complicated internal structures,the conventional Transfer Matrix Method (TMM) is of limited use. The CAE modeling and simulation is thereforerequired to incorporate commercial softwares: CATIA for geometry modeling, MSC/PATRAN for FE meshing and LMS/SYSNOISE for analysis. Main sources of difficulties in this study are led by complicated arrangement of reactive elements,perforated walls and absorption materials. The reactive elements and absorbent materials are modeled byapplying boundary conditions given by impedance. The perforated walls are modeled by applying the transfer impedanceon the duplicated node mesh. The CAE approach presented in this paper is verified by comparing with the theoreticalsolution of a concentric-tube resonator and is applied for industrial mufflers.
전수홍,한형석,김용훈,이가향 한국품질경영학회 2023 한국품질경영학회 학술대회 Vol.2023 No.0
해군 함정이 인도된 후 운용 간에 소음 및 진동에 의한 문제가 일부 발생하고 있다. 소음진동 문제가 지속적으로 발행할 경우 함정의 원활한 임무 수행에 지장을 초래할 수 있으며, 승조원의 근무 환경에 좋지 않은 영향을 미치기도 한다. 이러한 함정의 중요 성능에 대한 품질확보를 위하여 원인을 분석하고 개선방안을 마련하는 것이 중요하다. 본 연구에서는 운용함정에서 제기된 이상 소음진동 현상의 발생에 대한 원인 및 문제 분석을 위하여 해당 함정에 센서를 설치하고 실선시험을 통하여 점검을 수행하였다. 운용함정 소음진동 점검 결과 소음진동 발생 문제는 추진계통에서 발생하는 것이 대부분이었으며 추진기관의 가진력으로부터 야기되는 소음진동이 선체진동 및 폐기구 인근 격실의 과진동소음 문제로 나타나는 경우도 있었다. 이러한 문제를 해소하기 위하여 원인을 분석하고 구조보강 등의 개선 방안을 제시하였다. 본 연구에서 수행된 운용함정의 소음진동 문제 분석 결과 및 개선방안을 해당 함정 및 신조함정에 반영하여 향상된 품질의 함정을 확보함으로써 앞으로의 국방력 향상에 기여할 수 있을 것으로 기대한다.
일천궁에서 분리한 근권 내생 미생물의 식물생육증진 효과
전수홍,서종범,이석희,박준영,김대솔,김지아,정희영,강준원 한국약용작물학회 2023 한국약용작물학회지 Vol.31 No.3
Background: This study was conducted to evaluate the plant growth promoting effect of rhizobac- terial endophytes on Cnidium officinale Makino cultivated in Korea. Methods and Results: Twenty-four rhizobacterial were isolated from C. officinale Makino, and the L2 strain observed to have excellent plant growth promotion ability. Based on 16s rRNA sequence analysis, L2 was identified as Enterobacter ludwigii. The selected endophyte was evalu- ated for indole-3-acetic acid (IAA), siderophore, phosphate solubilizing assay, and extracellular enzyme activity to determine the growth promoting effect of the strain on C. officinale Makino under pot conditions. L2 produced IAA and siderophore and exhibited phosphate solubilizing activity. L2 was inoculated to the pot to evaluate the growth of C. officinale Makino. The shoot fresh weight and rhizome dryweight of C. officinale Makino inoculated with L2 after 5 weeks were higher than those of control samples. Conclusions: This study suggests that rhizobacterial endophytes can be used as a growth promoter and may be a potential for biofertilizer in the cultivation of Cnidium officinale Makino.
전수홍,M.W. Seo,Y.U. Cho,박원규,정의봉 국제구조공학회 2013 Structural Engineering and Mechanics, An Int'l Jou Vol.47 No.3
The natural sloshing frequencies of annular cylindrical TLD are parametrically investigated by experiment, aiming at the exploration of its successful use for suppressing the structural vibration of spar-type floating wind turbine subject to multidirectional wind, wave and current excitations. Five prototypes of annular cylindrical TLD are defined according to the inner and outer radii of acryl container, and eight different liquid fill heights are experimented for each TLD prototype. The apparent masses near the first and second natural sloshing frequencies are parametrically investigated by measuring the apparent mass of interior liquid sloshing to the acceleration excitation. It is observed from the parametric experiments that the first natural sloshing frequency shows the remarkable change with respect to the liquid fill height for each TLD model with different container dimensions. On the other hand, the second natural sloshing frequency is not sensitive to the liquid fill height but to the gap size, for all the TLD models, convincing that the annular cylindrical sloshing damper can effectively suppress the wave- and wind-induced tilting motion of the spar-type floating wind turbine.