http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Minimization of Surface Roughness and Machining Deformation in Milling of Al Alloy Thin-Walled Parts
De-Jun Cheng,Feng Xu,Sheng-Hao Xu,Chun-Yan Zhang,Sheng-Wen Zhang,Su-Jin Kim 한국정밀공학회 2020 International Journal of Precision Engineering and Vol.21 No.9
This study focused on investigating the surface roughness in the feed direction (R a -Fd), surface roughness in the transversedirection (R a -Td), and thin-walled parts deformation (TWD) during milling of Al alloy 5083. The response surface method(RSM) was used to conduct experiments and establish the models of R a -Fd , R a -Td , and TWD under various cutting parameters. The significance of cutting parameters on R a -Fd , R a -Td , and TWD was analyzed by analysis of variance. It was observedthat the R a -Fd and R a -Td are mainly influenced by the spindle speed, depth of cut, transverse size and feed rate, while the TWD is mainly influenced by the depth of cut. A comparison of RSM-optimum function and artificial bee colony (ABC)algorithm optimum programming was conducted to obtain the best cutting conditions leading to minimum R a -Fd, R a -Td and TWD simultaneously. From the presented results, ABC algorithm was able to obtain the better cutting strategy. Finally, theperformance of the proposed cutting strategy was verified by confirmation experiments.
MR T1 Image Segmentation of a Prostate Based on Distance Regularized Level Set Evolution
Yong-de Zhang,Jing-chun Peng,Gang Liu,Jin-gang Jiang,Yan-jiang Zhao 보안공학연구지원센터 2016 International Journal of Hybrid Information Techno Vol.9 No.7
Prostate segmentation from MRI is a necessary first step and plays an important role in clinical decision making process. A MR T1 Image segmentation method of the prostate based on distance regularized level set evolution (DRLSE) is proposed. To smooth the prostate image to reduce the noise, a preprocessed prostate image with Gaussian kernel and get an edge indicator is convolved. We construct an energy function with a distance regularization term and an external energy term containing the edge indicator and minimize it by solving the gradient flow which can be implemented with a finite difference scheme. In segmentation experiments, the impact of parameters λ , μ , α and ε in DRLSE model on the image segmentation is analyzed, and an optimal value of these parameters is given. The experiment results confirm the effectiveness of the MRI segmentation method of prostate for different situation of different patients.
Friction Experiment of Linear Motion Roller Guide THK SRG25
Cheng, De-Jun,Yang, Wan-Suk,Park, Je-Hong,Park, Tae-Jo,Kim, Su-Jin,Kim, Gyung-Ho,Park, Chun-Hong 한국정밀공학회 2014 International Journal of Precision Engineering and Vol.15 No.3
Friction is a characteristic that can be found in machine elements in common engineering use, and it has great effect on the machining performance of a machine tool. Linear motion (LM) guides supported by rolling elements are used for accurate positioning of precision machine. For accurate positioning, the frictional behavior of the LM guide must be understood. In this investigation, a new experiment is conducted to measure friction, and the behavior of LM roller guide friction is measured under various external loads, preloads, velocities, and lubricants. The results obtained from experiment are compared with reference data, and the experimental friction equation of LM roller guide THK SRG25 is achieved from experiment, which can be used to calculate LM roller guide friction and control positioning accuracy.
EFFECTS OF CARBON NANOTUBES ON RAT LIVER AND BRAIN
FU-DE WANG,CHAN JIN,LING-LING CAO,HAO LIANG,CHUN-WANG MA 성균관대학교(자연과학캠퍼스) 성균나노과학기술원 2014 NANO Vol.9 No.7
Carbon nanotubes (CNTs) have been widely applied in various ¯elds due to excellent physicaland chemical properties. As production and applications of nanotubes expand, public concernabout their potential risks to human health has also risen. In the present study, the e®ects ofCNTs on rat liver and brain by single intratracheal instillation were detected. CNTs [eithersingle-walled carbon nanotubes (SWCNTs) or multi-walled carbon nanotubes (MWCNTs)] couldbe seen in the lung and liver indicating the transfer of CNTs by blood stream. CNTs could induceoxidative stress in liver with elevated Malondialdehyde (MDA) level and degressive GSH level,superoxide dismutase (SOD) and CAT activity. To brain, maybe due to the blood brain barrierand the increased SOD and CAT activity, serious oxidative stress of brain did not occur.
일문전(Stephania delavayi Diels.) 메탄올, 부탄올, 에틸아세테이트 분획물의 항산화 및 세포증식억제 효과
이용순(Yong-Chun Li),김경희(Kyoung-Hee Kim),서홍덕(Hong-De Xu),박대훈(Dae-Hun Park),최연식(Yeon Shik Choi),황혜림(Hye-Rim Hwang),이민재(Min-Jae Lee),최종진(Jong-Jin Choi),권명상(Myung-Sang Kwon),육홍선(Hong-Sun Yook) 한국식품영양과학회 2009 한국식품영양과학회지 Vol.38 No.3
본 연구에서는 중국에서 급성 위장염에 대한 약제로 사용되어 오던 일문전의 메탄올 추출물을 이용하여 물, 에틸 아세테이트, 부탄올 층으로 분획한 뒤 항산화 활성과 항암활성을 측정하였다. DPPH 라디칼 소거능은 1,000 ㎍/mL 농도에서 부탄올(75.23%)>메탄올(68.11%)>에틸아세테이(63.58%)>물(50.13%) 순으로 나타났으며 환원력의 경우 용매 분획물의 농도가 증가함에 따라 환원력이 증가하는 경향을 나타내었다. DPPH 라디칼 소거능 및 환원력 모두 부탄올 분획층에서 좋은 활성을 나타내었다. 항암활성 측정결과 메탄올 추출물과 부탄올 분획물, 에틸 아세테이트 분획물에서 MDA-MB-231 cell과 MCF-7 cell에 대한 세포증식억제효과를 나타내었다. 이상의 결과에서 일문전의 용매 분획물은 항암 후보물질로의 가능성이 있을 것으로 사료된다. Stephania delavayi Diels. (S. delavayi Diels.) has been used as a drug for pain-relieving and acute gastroenteritis treatment in China. Because the major therapeutic mechanism of anti-inflammatory drug is to inhibit the cyclooxygenase (COX)-2 and because COX-2 proteins inhibit apoptosis, COX-2 inhibitor has been thought as the anticancer drug candidate. For this reason, we examined S. delavayi Diels. as an anticancer drug. S. delavayi Diels. was fractionated with methanol and then partitioned with ethyl acetate, n-butanol and water. The antioxidant activity was evaluated by 1,1-diphenyl-2-picrylhydrazyl (DPPH) radical scavenging activity and reducing power. DPPH radical scavenging activities of the crude fractions at the concentration of 1,000 ㎍/mL were 75.23% (n-butanol), 68.11% (methanol), 63.58% (ethyl acetate), and 50.13% (water). The reducing power increased according to the concentration in dose-dependent manner. Also, when the antiproliferation effects of each fraction against human breast cancer cell-lines MDA-MB-231 and MCF-7 were examined, methanol extract, n-butanol fraction and ethyl acetate fraction exhibited cell proliferative inhibition effects in both cell-lines whereas water fraction did not. Among the crude fractions, the n-butanol fraction exhibited the most potent anti-proliferation effect. In conclusion, fractions from S. delavayi Diels. are promising anticancer drug candidates.