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신경망 신경망을 적용한 온톨로지 기반의 Focused Crawling
ZhengHai-tao,강보영(Bo-young Kang),남궁현(Hyun Namgoong),김홍기(Hong-Gee Kim) 한국정보과학회 언어공학연구회 2007 한국정보과학회 언어공학연구회 학술발표 논문집 Vol.2007 No.10
Focused crawling은 검색시스템의 구축을 위한 웹 문서 수집단계에서, 미리 정의된 토픽 집합들과 관련성을 가지는 웹 문서를 수집하기 위하여 제안되었다. 이러한 focused crawling 연구에서 보다 효과적인 웹 문서 수집을 위해 주어진 토픽에 대한 양질의 배경지식을 제공할 수 있도록 온톨로지가 활발히 활용되어왔다. 그러나 기존의 온톨로지 기반 focused crawling 연구는 토픽과 웹 문서 간의 관련성 측정을 위하여, 주어진 토픽과 관련있는 온톨로지 내 각 개념들에 직관에 의존한 가중치를 부여하여 활용하였다. 하지만 이러한 직관에 의존한 가중치부여 기법은 안정된 수집결과를 도출할 수 있는 최적화된 가중치 값을 얻기가 힘든 한계가 있다. 따라서 본 논문에서는 이러한 개념에 대한 가중치가 학습에 의하여 자동으로 결정되도록, 인공신경망을 적용한 온톨로지 기반 focused crawling 기법을 제안한다. 웹 상에서 제안된 시스템의 성능을 실험한 결과 기존의 온톨로지 기반 수집 기법에 비하여 보다 향상된 결과를 보임을 알 수 있었다.
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Study on logarithmic crowning of cylindrical roller profile considering angular misalignment
Zhenghai Wu,Yingqiang Xu,Sier Deng,Kaian Liu 대한기계학회 2020 JOURNAL OF MECHANICAL SCIENCE AND TECHNOLOGY Vol.34 No.5
The angular misalignment of cylindrical rollers causes the stress edge effect at roller ends to be aggravated, which would affect bearing capacity and fatigue life of bearings. Therefore, based on the roller angular misalignment, the geometric interference model of the cylindrical contact pair was established in this paper. Thereafter, two types of logarithmic crowning models were theoretically deduced, in which design redundancy was considered through special treatment of pre-pressure. Taking the aero-engine main shaft bearing as an example, contact characteristics of the cylindrical roller with these two logarithmic profiles were studied by the DC-FFT method and the conjugate gradient method (CGM). The results show that two profiles can effectively eliminate the stress edge effect, improve contact pressure distribution and subsurface stress field of the roller in misalignment state, and at the same time ensure fine contact characteristics in alignment state. The research can provide a theoretical basis and reference for finite line contact pairs under angular misalignment.
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Lingling Li,Zhenghai Liu,Jiaye Xu,Xuedong Ma 한국전기전자재료학회 2020 Transactions on Electrical and Electronic Material Vol.21 No.3
In order to enhance the segregation eff ect of material particles in a hemispherical shell swing-oscillating trough under combination swing-oscillating, by means of three dimensional discrete element method, and by use of the two-dimensional dry granules of plastic ball and steel ball, the discrete element simulation study of particle segregation process is carried out in turn in three cases, which is composed of a single swing-oscillating in smooth trough, a combination swing-oscillating in smooth trough, and a combination swing-oscillating in adding bulge trough. The particle segregation eff ect was evaluated by particle volume concentration and combined with segregation cloud picture simulated. The result indicates that segregation effect of combination swing-oscillating is better than that in single swing-oscillating; layering eff ect of the trough added bulge is better than that in the smooth trough. And compared to single swing-oscillating in smooth trough, the degree of segregation of particles in added bulge trough can be increased by 10–15% when being combination swing-oscillating.
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이준신,Vinh Ai Dao,김경해,김영국,Duy Nguyen Van,Zhenghai Jin 한국물리학회 2008 THE JOURNAL OF THE KOREAN PHYSICAL SOCIETY Vol.53 No.2
Thin-film silicon/crystaline silicon heterojunction-type solar cels, combining the low-cost, low- temperature and light-weight of thin-film silicon with the high efficiency and high stability of crystaline silicon (c-Si), are studied widely due to the increased need for terrestrial and satelite applications. A major aspect when dealing with thin-film silicon/crystaline silicon heterojunction solar cels is quality of the silicon film-crystaline silicon hetero-interface. In this study, the carrier transport mechanisms in mixed phase (amorphous and microcrystaline) thin-film silicon/p type crystaline silicon heterojunction for various thin-film thicknesses and SiH4/H2 ratios are investi- gated. The electrical properties are strongly affected by the defect state distribution and the band offset at the hetero-interface. Two carrier transport mechanisms are recognized. The recombination process involving the interface states on the thin-film silicon side dominates at low forward bias (V < 0.4 V), whereas multi-step tunneling capture emission (MTCE) dominates at the high forward bias (0.4 < V < 0.8 V).
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Qian Zhang,Xindi Mei,Cheng Zhang,Juan Li,Nana Chang,Dilihuma Aji,Weifeng Shi,Yuhai Bi,Zhenghai Ma 대한수의학회 2021 Journal of Veterinary Science Vol.22 No.4
Background: The H5 avian influenza viruses (AIVs) of clade 2.3.4.4 circulate in wild and domestic birds worldwide. In 2017, nine strains of H5N6 AIVs were isolated from aquatic poultry in Xinjiang, Northwest China. Objectives: This study aimed to analyze the origin, reassortment, and mutations of the AIV isolates. Methods: AIVs were isolated from oropharyngeal and cloacal swabs of poultry. Identification was accomplished by inoculating isolates into embryonated chicken eggs and performing hemagglutination tests and reverse transcription polymerase chain reaction (RT-PCR). The viral genomes were amplified with RT-PCR and then sequenced. The sequence alignment, phylogenetic, and molecular characteristic analyses were performed by using bioinformatic software. Results: Nine isolates originated from the same ancestor. The viral HA gene belonged to clade 2.3.4.4B, while the NA gene had a close phylogenetic relationship with the 2.3.4.4C H5N6 highly pathogenic avian influenza viruses (HPAIVs) isolated from shoveler ducks in Ningxia in 2015. The NP gene was grouped into an independent subcluster within the 2.3.4.4B H5N8 AIVs, and the remaining six genes all had close phylogenetic relationships with the 2.3.4.4B H5N8 HPAIVs isolated from the wild birds in China, Egypt, Uganda, Cameroon, and India in 2016–2017, Multiple basic amino acid residues associated with HPAIVs were located adjacent to the cleavage site of the HA protein. The nine isolates comprised reassortant 2.3.4.4B HPAIVs originating from 2.3.4.4B H5N8 and 2.3.4.4C H5N6 viruses in wild birds. Conclusions: These results suggest that the Northern Tianshan Mountain wetlands in Xinjiang may have a key role in AIVs disseminating from Central China to the Eurasian continent and East African.
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