• 대한기계학회논문집
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• 제13권4호
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• pp.789-798
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• 1989

본 연구에서는 평균속도구배를 용이하게 변화시킬 수 있는 전단유동 발생기를 제작하였다. 최고속도구배는 38se $c^{-1}$까지 얻을 수 있으며 최대중심선 속도는 15m/sec까지이다. 10개의 채널(두께 2mm인 알루미늄판)로 유동단면을 등분하 였으며, 각 채널의 내부저항조절 방법으로 마름모형태의 막대인 knob을 설치하였다.

• Restorative Dentistry and Endodontics
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• 제45권2호
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• pp.22.1-22.10
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• 2020

Objectives: This study investigated the influence of glide path size and operating kinetics on the time to reach the working length and the fracture resistance of Twisted File (TF) and Endostar E3 files. Materials and Methods: A total of 120 mandibular single-rooted premolars were selected. Two methods of kinetic motion (TF adaptive and continuous rotary motion) and file systems (TF and Endostar E3) were employed. The files were used in root canals prepared to apical glide path sizes of 15, 20, and 25. The time taken to reach the working length and the number of canals used before the instrument deformed or fractured were noted. Fractured instruments were examined with scanning electron microscopy. Results: The TF system took significantly more time to reach the working length than the Endostar E3 system. Both systems required significantly more time to reach the working length at the size 15 glide path than at sizes 20 and 25. A greater number of TFs than Endostar E3 files exhibited deformation, and a higher incidence of instrument deformation was observed in adaptive than in continuous rotary motion; more deformation was also observed with the size 15 glide path. One TF was fractured while undergoing adaptive motion. Conclusions: No significant difference was observed between continuous rotary and adaptive motion. The TF system and adaptive motion were associated with a higher incidence of deformation and fracture. Apical glide path sizes of 20 and 25 required significantly less time to reach the working length than size 15.

• 대한기계학회논문집B
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• 제39권1호
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• pp.79-88
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• 2015

본 연구에서는 유한차분법(FDM)을 적용한 혼성 격자볼츠만 방법(HLBM)을 이용하여 직사각 형태를 갖는 공동형상 내 혼합특성에 대하여 수치적으로 연구하였다. 유동장은 다중 완화시간을 적용한 격자볼츠만 방법(LB-MRT)을 사용하였으며, 농도장은 두 물질의 질량은 같고 두 물질 사이의 상호작용이 없다고 가정한 Passive Scalar 방법을 사용하였다. 먼저, 정사각형과 종횡비가 2인 직사각형의 공동형상 내 유동해석 결과를 기존의 신뢰성 있는 연구결과와 비교하여 HLBM의 신뢰성을 검토하였다. 이를 토대로 다양한 종횡비를 갖는 공동형상에서 Pe수를 변화시키며 공동형상 내부에서의 혼합특성과 물질전달 형태에 대하여 파악하였다.

• 대한기계학회논문집B
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• 제37권7호
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• pp.683-693
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• 2013

본 연구에서는 혼성 격자볼츠만 방법(HLBM)을 이용하여 상판이 일정한 속도로 움직이는 공동 형상 내부에서의 혼합 특성에 대하여 수치적으로 연구하였다. 먼저, 공동 형상에서 기존의 신뢰성 있는 유동장 결과와의 비교를 통해 LB-SRT 모델과 LB-MRT 모델의 신뢰성을 검토하였다. 두 모델 모두 기존의 연구결과와 유사한 결과를 보였으나, LB-MRT 모델이 LB-SRT 모델보다 높은 Re수에서는 수치적 안정성이 높은 것을 확인하였다. 수치적 안정성이 좋은 LB-MRT 모델을 토대로 유한차분법을 적용한 HLBM을 이용하여 공동 형상 내부에서의 농도장을 수치 해석하였다. Re수와 Pe수를 변화하여 공동 형상 내부의 혼합 특성과 물질 전달 형태에 대하여 파악하였다.

• ALGAE
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• 제37권4호
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• pp.249-264
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• 2022

Two genera of the Rhodymeniales, Halopeltis and Leptofauchea, are here reported for the first time from the Hawaiian Islands and represent the deepest records for both genera. Molecular phylogenetic analyses of cytochrome oxidase subunit I (COI), rbcL, and large subunit ribosomal DNA (LSU) sequences for Hawaiian specimens of Leptofauchea revealed one well-supported clade of Hawaiian specimens and three additional lineages. One of these clades is described here as Leptofauchea huawelau sp. nov., and is thus far known only from mesophotic depths at Penguin Bank in the Main Hawaiian Islands. L. huawelau sp. nov. is up to 21 cm, and is the largest known species. An additional lineage identified in the LSU and rbcL analyses corresponds to the recently described L. lucida from Western Australia, and is a new record for Hawai'i. Hawaiian Halopeltis formed a well-supported clade along with H. adnata from Korea, the recently described H. tanakae from mesophotic depths in Japan, and H. willisii from North Carolina, and is here described as Halopeltis nuahilihilia sp. nov. H. nuahilihilia sp. nov. has a distinctive morphology of narrow vegetative axes that harbor constrictions along their length. The current distribution of H. nuahilihilia includes mesophotic depths around W. Maui, W. Moloka'i, and the island of Hawai'i in the Main Hawaiian Islands. Few reproductive characters were observed because of the small number of specimens available; however, both species are distinct based on phylogeny and morphology. These descriptions further emphasize the Hawaiian mesophotic zone as a location harboring many undescribed species of marine macroalgae.