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FW-H 방법을 이용한 잠수함 표면 처리에 따른 소음 전산 해석
김승기(Seunggi Kim),유재영(Jaiyoung Ryu) 대한기계학회 2021 대한기계학회 춘추학술대회 Vol.2021 No.11
Submarine has been performed for national defense activities representatively. Underwater Radiated Noise (URN) which emitted during underwater vehicle operation is directly related to the survivability of the underwater vehicle. This study focused on examining the effects of surface treatment on noise aspects in submarine. Numerical simulations were conducted for two cases : smooth surface as a reference case, and V-type riblet. To solve the incompressible fluid flow passing the submarine, the Reynolds-averaged Navier-Stokes equation coupled with the k-ω SST turbulence model was used. As a result of examining the noise radiation around the submarine, it was confirmed that it was necessary to pay attention to the noise radiation effect in the middle part of the submarine body. And the results indicate that overall sound pressure level can be reduced about maximum 4 dB at far-field by applying riblet surface. This study provides more enhanced understanding about the surface design on underwater vehicles to reduce underwater radiated noise.
전산 소음 해석 기법을 이용한 잠수함 표면 처리에 따른 소음 효과 관찰
김승기(Seunggi Kim),유재영(Jaiyoung Ryu) 한국전산유체공학회 2021 한국전산유체공학회지 Vol.26 No.4
Submarine has been performed for national defense activities representatively as a multi-purpose underwater vehicle. Underwater Radiated Noise (URN) which emitted during underwater vehicle operation is directly related to the survivability of the underwater vehicle. This study focused on examining the effects of surface treatment on noise aspects in whole submarine body for the first time. Prior to the acoustic analysis on the submarine model, the acoustic analysis procedure using commercial CFD software was verified using a 2D cylinder model. Acoustic analysis on submarine model was conducted for two cases: smooth surface as a reference case, and a few micrometers of V-type applied riblet case. To solve the incompressible fluid flow passing the submarine, the Reynolds-averaged Navier-Stokes (RANS) equation coupled with the k-ω SST turbulence model was used. For acoustic analysis, the Ffowcs Williams and Hawkings acoustic analogy, which calculates flow-induced noise by designating a physical wall as a noise source, was used. The noise effects according to the surface treatment on submarine shape were examined by comparing overall sound pressure level (OASPL) between smooth and riblet case and the results indicate that noise around submarine shape was reduced about 4.3 dB in maximum on surface-treated area. However, when calculating OASPL excluding noise below 20 Hz, which is a frequency range where noise does not propagate, the noise tends to increased due to riblet shape. This study provides established procedure in acoustic analysis on whole submarine body and a new perspective that underwater radiation noise should be considered when designing surface treatment on submarine.
Seo, Seunggi,Yeo, Byung Chul,Han, Sang Soo,Yoon, Chang Mo,Yang, Joon Young,Yoon, Jonggeun,Yoo, Choongkeun,Kim, Ho-jin,Lee, Yong-baek,Lee, Su Jeong,Myoung, Jae-Min,Lee, Han-Bo-Ram,Kim, Woo-Hee,Oh, Il-K American Chemical Society 2017 ACS APPLIED MATERIALS & INTERFACES Vol.9 No.47
<P>The reaction mechanism of area-selective atomic layer deposition (AS-ALD) of Al2O3 thin films using self-assembled monolayers (SAMs) was systematically investigated by theoretical and experimental studies. Trimethylaluminum (TMA) and H2O were used as the precursor and oxidant, respectively, with octadecylphosphonic acid (ODPA) as an SAM to block Al2O3 film formation. However, Al2O3 layers began to form on the ODPA SAMs after several cycles, despite reports that CH3-tenninated SAMs cannot react with TMA. We showed that TMA does not react chemically with the SAM but is physically adsorbed, acting as a nucleation site for Al2O3 film growth. Moreover, the amount of physisorbed TMA was affected by the partial pressure. By controlling it, we developed a new AS-ALD Al2O3 process with high selectivity, which produces films of similar to 60 nm thickness over 370 cycles. The successful deposition of Al2O3 thin film patterns using this process is a breakthrough technique in the field of nanotechnology.</P>
Dong Hyun Kim,Seunggi Min,Hyun Joo Lee,Hee-June Kim,Hoseok Lee,Jong Pil Yoon 대한견주관절의학회 2019 대한견주관절학회지 Vol.22 No.1
A 73-year-old woman presented with a recurrent cystic mass around her left olecranon. She had a history of 8 steroid injections due to elbow pain beginning 3 years ago and twice had undergone aspiration of olecranon bursitis that developed two months prior to presentation. She had been taking medications for hypertension and diabetes with no pertinent past history. On magnetic resonance imaging (MRI), there were multiple nodules in the olecranon bursa, which were isointense to muscle on T1-weighted images and hyperintense to muscle on T2-weighted images. Our initial diagnosis was synovial chondromatosis. On bursoscopy, masses of gray-white colored nodules were observed in the bursa. Finally, synovial chondromatosis and non-tuberculous mycobacterial infection were concurrently diagnosed. In conclusion, uncalcified synovial chondromatosis and rice bodies can have similar visual and MRI characteristics; therefore, we suggest that clinicians should be aware of the possibility of other infections in cases of this type.
Joo Han Oh,Seunggi Min,Jae Wook Jung,Hee-June Kim,Jae Yoon Kim,Seok Won Chung,Joon Yub Kim,Jong Pil Yoon 대한견주관절의학회 2018 대한견주관절학회지 Vol.21 No.2
Background: The purpose of this study was to evaluate the clinical outcomes and complications of hook plate fixation in acromioclavicular (AC) joint dislocations and distal clavicle fractures. Methods: We retrospectively reviewed a series of 60 consecutive patients with hook plate fixation for AC joint dislocation (group I) and distal clavicle fracture (group II). Groups I and II had 39 and 21 patients, respectively. Clinical results were evaluated using the pain visual analogue scale (VAS), simple shoulder test, and Constant-Murley scores. In addition, subacromial erosion and stiffness were evaluated as complications. Results: At the removal, the pain VAS was 2.69 ± 1.30 and 4.10 ± 2.14 in groups I and II, respectively, which were significantly different (p=0.003). The simple shoulder test score was 9.59 ± 1.60 and 7.81 ± 2.67 in groups I and II, respectively, which were also significantly different (p=0.002). Subacromial erosion was significantly more frequent in group II (14/21 patients, 66.7%) than in group I (15/39 patients, 38.5%) (p=0.037), and stiffness was also higher in group II (17/21 patients, 81.0%) than in group I (22/39 patients, 56.4%), but it was not significant. Conclusions: Hook plate fixation showed good clinical and functional results for the treatment of acute unstable AC joint dislocation and distal clavicle fracture. But, in distal clavicle fractures, there are more subacromial erosion and stiffness compare with acute unstable AC joint dislocation.