http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Toughness and fracture mechanisms of glass fiber/aluminum hybrid laminates under tensile loading
Sung-Choong Woo,Nak-Sam Choi,Young-Wook Chang 대한기계학회 2007 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.21 No.12
Tensile properties and fracture toughness of monolithic aluminum (Al), glass fiber reinforced plastics (GFRPs) and glass fiber/aluminum hybrid laminates (GFMLs) were examined in relation to the fracture processes of plain coupon and single-edge-notched specimens. Elastic modulus and ultimate tensile strength of GFMLs showed characteristic dependences on the kind of Al, fiber orientation and the Al/fiber layer composition ratio. Fracture toughnesses KC and GC of A-GFML-UD were comparable to those of GFRP-UD and were much superior to monolithic Al. However, GFML with a transverse crack parallel to the fiber layer deteriorated largely in toughness. Microscopic observation of the fracture zone in the vicinity of the crack tip revealed various modes of micro-cracks in the respective layers as well as fiber fractures and delamination between fiber/Al layers. Such damage advances in GFMLs dependent on the orientation of the fiber layer and the Al/fiber composition ratio strongly influenced the strength and toughness of GFMLs.
Adaptive Tracking Controller Design for Welding Mobile Manipulator with Unknown Parameters
Sang-Bong Kim,Tan-Tung Phan,Nak-Soon Choi,Hak-Kyeong Kim 한국해양공학회 2009 韓國海洋工學會誌 Vol.23 No.2
This paper presents an adaptive tracking control method for a welding mobile manipulator with several unknown parameters such as the last length of the manipulator, the wheel radius and the distance from the center to the wheel. The mobile manipulator consisted of the manipulator and the mobile-platform. Kinematic modelings for the manipulator and the mobile-platform with several unknown parameters were produced. The tracking error vectors for the manipulator and the mobile-platform were defined. These adaptive controllers were designed based on the Lyapunov function to guarantee the stability of the whole system when the mobile manipulator performs a welding task. Update laws were also designed to estimate the unknown dimensional parameters. To implement the designed controllers, a control system integrated with PIC16F877 microporcessors and a TMS320C32 DSP was developed. Simulation and experimental results are presented to show the effectiveness of the proposed controller.
Nak Jung Choi,Hyun-Ju Kim,Bong-Choon Lee,Sang-Min Kim,Shin-Hwa Kim,Jongsun Park 한국응용곤충학회 2019 한국응용곤충학회 학술대회논문집 Vol.2019 No.04
Nilaparvata lugens, brown planthoppers, is one of important pests on rice. Korean N. lugens is migrated from China and causing severe damages on rice in early September in Korea. For identifying biotypes of these N. lugens based on complete mitochondrial genomes, we completed mitochondrial genome of N. lugens captured in Hadong-gun, Gyoungsang-nam province in Korea. The circular mitogenome of N. lugens is 17,610 bp including 13 protein-coding genes, two ribosomal RNA genes, 22 transfer RNAs, and a single large non-coding region of 2,424 bp. The base composition was AT-biased (89.5%). 112 single nucleotide polymorphisms (SNPs) and 59 insertions and deletions are identified by comparing with Chinese N. lugens. Based on phylogenetic trees together with those of N. lugens captured in China, no clear phylogenetic relationship along with five biotypes, requiring more researches to achieve biotype identification including detailed analysis of sequence variations on mitochondrial genomes and whole genome analysis of N. lugens in near future.
Choi, Sun-Young,Lee, Kyung-Jin,Kim, Hyung-Gyun,Han, Eun-Hee,Chung, Young-Chul,Sung, Nak-Ju,Jeong, Hye-Gwang Korean Chemical Society 2006 Bulletin of the Korean Chemical Society Vol.27 No.9
Kahweol and cafestol significantly reduced t-BHP-induced oxidative injuries in cultured rat hepatocytes, as determined by cell cytotoxicity, intracellular glutathione (GSH) content and lipid peroxidation in a dose-dependent manner. In addition, kahweol and cafestol provided good protection from the t-BHPinduced production of intracellular reactive oxygen species and DNA damage. The in vivo study showed that pretreatment with kahweol and cafestol prior to the administration of t-BHP significantly prevented the increase in serum levels of hepatic enzyme markers (alanine aminotransferase and aspartate aminotransferase) and reduced oxidative stress, such as GSH content and lipid peroxidation, in the liver in a dose-dependent manner. The histopathological evaluation of the livers also revealed that kahweol and cafestol reduced the incidence of liver lesions induced by t-BHP. Taken together, these results support the anti-oxidative role of kahweol and cafestol and demonstrate that kahweol and cafestol can protect hepatocytes from oxidative stress.
Four-channel single incision laparoscopic cholecystectomy using a snake retractor
Nak Song Sung,In Seok Choi,Ju Ik Moon,Yu Mi Ra,Sang Eok Lee,Won Jun Choi 대한외과학회 2014 Annals of Surgical Treatment and Research(ASRT) Vol.87 No.2
Purpose: Single incision laparoscopic cholecystectomy (SILC) is a widely used method of performing cholecystectomy. A common technique used in SILC is a 3-channel method. However, exposure of Calot’s triangle is limited in conventional 3-channel SILC. Therefore, we herein report the adequacy and feasibility of 4-channel SILC using a snake retractor. Methods: Four hundred and fifteen SILC cases were performed between April 2010 and February 2013. We performed 326 SILC cases between April 2010 and September 2012 using the 3-channel method. We introduced a snake retractor for liver traction in October 2012, and 89 cases of 4-channel SILC using snake retractor have been performed since. Results: Thirty patients (9.2%) in the 3-channel SILC group, and 23 patients (25.8%) in the 4-channel SILC group, were treated with percutaneous transhepatic gallbladder drainage insertion because of acute inflammation of the gallbladder (GB) before operation (P < 0.001). The mean operating time was 53.0 ± 25.8 minutes in the 3-channel SILC group and 51.9 ± 18.6 minutes in the 4-channel SILC group (P = 0.709). In the 3-channel SILC group, mean hospital stay was 3.0 ± 3.3 days whereas it was 2.6 ± 0.9 days in the 4-channel SILC group (P = 0.043). There were a total 9 cases (2.1%) of additional port usages, 6 cases (1.8%) in the 3-channel SILC group and 3 cases (3.4%) in the 4-channel SILC group (P = 0.411), due to cystic artery bleeding and bile leakage from gallbladder bed, but there were no open conversions. Conclusion: Benign diseases of the GB can be operated on using SILC with the 4-channel method using a snake retractor.