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FEW 공정을 이용한 알루미늄 합금과 고장력강의 접합에 관한 연구
Shuqiang Lyu,송현정(Hyun Jung Song),진다정(Da Jeong Jin),박상언(Sang Eon Park),김지훈(Ji Hoon Kim),조해용(Hae Yong Cho) 대한기계학회 2022 大韓機械學會論文集A Vol.46 No.3
FEW(friction element welding)는 물리적 및 화학적 특성으로 인해 기존 용접 방법으로 접합하기 어려운 이종 금속판재를 접합하는 기술이다. 이 공정은 고속 회전하는 리벳으로 알루미늄 합금과 같은 경량합금의 상부 판재를 관통하고 마찰열로 용융시켜 하부 판재와 접합함으로써 기계적 결합과 야금적 결합의 특징을 동시에 갖는다. 본 연구에서는 FEW 공정을 적용하여 알루미늄 합금인 Al6061-T6과 고장력강판 DP1470의 접합을 유한요소 해석을 통해 시뮬레이션하고 접합 실험과 비교 · 분석하였다. 시뮬레이션과 실험의 접합부 단면형상을 확인하고 접합강도를 측정한 결과, FEW 공정은 알루미늄 합금과 고장력강의 이종재료 접합에 적용 가능할 것으로 판단된다. FEW (friction element welding) is a technique for joining dissimilar metal plates which are difficult to join using conventional welding methods due to their physical and chemical properties. In this process, a high-speed rotating rivet penetrates the upper plate of a lightweight alloy, such as aluminum alloy, melts it with frictional heat, and joins it with the lower steel plate, to impart the characteristics of mechanical and metallurgical bonding. In this study, the bonding of aluminum alloy Al6061-T6 and high-strength steel sheet DP1470 was simulated through finite element analysis by applying the FEW process, the results of which were analyzed and compared with the bonding test. By checking the cross-sectional shape and measuring the joint strength in the simulation and test, it was concluded that the FEW process can be applied to join dissimilar materials, for instance, aluminum alloy and high strength steel.
Hak Ju Lee,마응천,Da Hyun Lyu,Uk Koo,남궁우,홍성수,Kem Ok Kim,김경호,이동호 대한약학회 2012 Archives of Pharmacal Research Vol.35 No.1
Seven prenylated flavanoids, licoflavone C (1), cyclomulberrin (2), neocyclomorusin (3), sanggenon I (4), morusin (5), kuwanon U (6) and kuwanon E (7), and three 2-arylbenzofurans, moracin P (8), moracin O (9), and mulberrofuran Q (10) were isolated from the MeOH extract of Mori Cortex Radicis. Among these, compounds 2-7 enhanced cell viability in a dose-dependent manner against sodium nitroprusside-induced cell death in neuroblastoma SH-SY5Y cells, which was measured by MTT reduction assay (EC50 values of 4.4, 5.6, 8.0, 6.4, 8.7, and 11.9 μg/mL, respectively). Among 10 compounds, C-3 prenylated flavones (2, 3, and 5) and prenylated flavanones (4, 6, and 7) showed cell protection. However, compound 1 which lacks the prenyl group at C-3 and three 2-arylbenzofurans (8-10) did not show protective effect. The order of cell protection was as follow: C-3 prenylated flavones (2, 3, and 5) > prenylated flavanones (4, 6, and 7) > 2-arylbenzofurans (8-10) and flavone (1). From this result, we show that some prenylated flavones and flavanones might protect neuronal cells against nitrosative stress-mediated cell death. Even though further evaluations are necessary in vitro and in vivo study, we carefully suggest that some prenylated flavonoids from Mori Cortex Radicis might protect neuronal cells from neurodegenerative diseases.
추천 시스템에서의 효율적인 행렬 분해 모델을 위한 정밀도 변환 기법
유재서 ( Jae-seo Yu ),고윤용 ( Yun-yong Ko ),배홍균 ( Hong-kyun Bae ),강석원 ( Seokwon Kang ),유용승 ( Yongseung Yu ),박영준 ( Yongjun Park ),김상욱 ( Sang-wook Kim ) 한국정보처리학회 2021 한국정보처리학회 학술대회논문집 Vol.28 No.1
최근 딥러닝 분야에서 모델 학습을 가속화하기 위해, 실수 표현 시 사용하는 비트 수를 줄이는 양자화 연구가 활발히 진행되고 있다. 본 논문은 추천 시스템 모델 중 하나인 행렬 분해 모델(Matrix Factorization, MF)에 대한 양자화 수행 시, 발생할 수 있는 학습 정확도 손실을 방지하기 위한 정밀도 변환 방안을 제시한다. 우리는 실세계 데이터셋을 이용한 실험을 통해, 제안 방안이 적용된 MF 모델은 양자화 기법이 적용되지 않은 모델과 비슷한 추천 정확도를 보이며, 약 30% 개선된 속도로 학습됨을 확인할 수 있었다.
Kim, Seung Min,Lee, Da Won,Kim, You Jeong,Jun, Lyu Jin,Park, Hyun Kyung,Kim, Ye Ji,Jeong, You Yong,Lee, Sung Ho,Kwon, Mun Gyeong,Jeong, Joon Bum The Korean Society of Fisheries and Aquatic Scienc 2021 Fisheries and Aquatic Sciences Vol.24 No.4
In this study, a fish metabolic accelerator (a combination of butaphosphan and cyanocobalamin [BPC]) was injected into the muscle of the olive flounder, Paralichthys olivaceus, to investigate its effect on immunity and stress in fish maintained at low temperatures. A single dose of BPC was injected (100 mg/kg body weight) into the olive flounder, and its immunity and stress were observed after one and two weeks. Immunity tests revealed the presence of lysozyme (LZM), nitroblue tetrazolium (NBT), myeloperoxidase (MPO), anti-protease (AP), glutathione peroxidase (GPx), and total immunoglobulin (TIg). BPC injection was found to increase immunity activity compared to the control group. In particular, there was significantly high GPx activity. There was similarly high activity for MPO and GPx in the first week following the injection, followed by significant differences between the BPC-injected and control groups in the second week. There was a reduced low water-temperature stress response in the BPC-injected fish, as evidenced by the cortisol and glucose levels of the control and BPC groups. Lower levels were also observed in the BPC group than the control group during the second week. Cortisol levels were significantly lower in the BPC group than the control group. Histological examinations were conducted in the first and second weeks after the intramuscular injection of the recommended BPC dose to confirm the safety of BPC in aquaculture. There were no abnormalities observed in any tissue samples. This study confirms that the injection of BPC is safe even when used in a culture situation. BPC helps relieve stress and improves non-specific immune responses (innate immunity) in the olive flounder.
Monitoring of emaciation disease in cultured Paralichthys olivaceus of Jeju island during 2014-2015
Kim, Seung Min,Jun, Lyu Jin,Lee, Da Won,Park, Hyun Kyung,Jeong, Hyun Do,Kim, Jong Sung,Jeong, Joon Bum The Korean Society of Fisheries and Aquatic Scienc 2018 Fisheries and Aquatic Sciences Vol.21 No.6
This study investigated the trend in emaciation infection outbreak in olive flounder (Paralichthys olivaceus) of Jeju island, South Korea, during 2014-2015. A total of 900 fish were systematically examined by PCR method using the EM-F/EM-R primer set in April, May, September, November, and December 2014, and the infection rate was recorded. In 2015, the same examination was conducted in March, May, July, and October but with 660 fish. It was found that the infection rate was 18.3~71.6% in 2014, which increased to 16.3~90.3% in 2015. Furthermore, September and December in 2014 and March, July, and October in 2015 showed a relatively higher infection rate. According to the infection trend analysis, which depended on the sample size, the infection occurred in all of fish sizes in this study and 11~30 cm fish group showed the highest infection rate. Histological examination confirmed that the kidney areas of the emaciating infected olive flounder contained several spores of $4{\sim}9{\mu}m$, and in severe cases, the elimination and destruction of tissue were confirmed by PCR. Thus, an important portion of farmed olive flounders in the Jeju region suffers from emaciation disease. This epidemiological survey serves as a useful reference on the emaciation disease of cultured olive flounders in Jeju