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61.
We propose a recursive design scheme of a state observer for multiple-input-multiple-output, partly lower triangular nonlinear systems. The design begins from the subdynamics far from the output and propagates to the subdynamics close to the output, recalling the backstepping scheme for nonlinear control. The proposed class of systems is fairly general since it includes nonuniformly observable and/or detectable multioutput systems. Error convergence to zero is proved assuming boundedness of inputs a posteriori (i.e., after the design), which is preferable whereas most results in the literature assume the boundedness; a priori (i.e., before the design). A global observer is proposed with the global Lipschitz condition of the system, but without any restriction on the size of Lipschitz coefficient. The Lipschitz condition can be removed when a semiglobal observer is of interest. 相似文献
62.
This paper presents an automatic construction of Korean WordNet from pre-existing lexical resources. We develop a set of automatic word sense disambiguation techniques to link a Korean word sense collected from a bilingual machine-readable dictionary to a single corresponding English WordNet synset. We show how individual links provided by each word sense disambiguation method can be non-linearly combined to produce a Korean WordNet from existing English WordNet for nouns. 相似文献
63.
Ford J.E. Goossen K.W. Walker J.A. Neilson D.T. Tennant D.M. Seo Yeon Park Sulhoff J.W. 《IEEE journal of selected topics in quantum electronics》2004,10(3):579-587
Dynamic gain equalization filters (DGEFs) are important for high-performance wavelength division multiplexed (WDM) communications. One of the first demonstrated DGEF used a micromechanical etalon filter array illuminated with free-space spectral demultiplexing optics. Here, we present subsequent research on etalon-based dynamic spectral filters, including vertical device structures which linearize and reduce the drive voltage from 70 to 40 V, and spatially-segmented etalons which allow channelized spectral equalization and further reduce drive voltage. We describe a prototype using a simplified cylindrical optomechanical package with a 104-nm broadband spectral response, 7.5-dB insertion loss and less than 16-V operation voltage. Finally, we show the use of a 42-nm bandwidth DGEF prototype with feedback stabilization to more than double the number of channels and operating bandwidth of a conventional Erbium-doped fiber amplifier while maintaining < 1-dB power uniformity. 相似文献
64.
This paper presents a risk assessment methodology for underground construction projects. A formalized procedure and associated tools were developed to assess and manage the risks involved in underground construction. The suggested risk assessment procedure is composed of four steps of identifying, analyzing, evaluating, and managing the risks inherent in construction projects. The main tool of the proposed risk assessment methodology is the risk analysis software. The risk analysis software is built upon an uncertainty model based on fuzzy concept. The fuzzy-based uncertainty model is designed to consider the uncertainty range that represents the degree of uncertainties involved in both (1) probabilistic parameter estimates and (2) subjective judgments. Other tools developed in this study include the survey sheets for collecting risk-related information and the detail check sheets for risk identification and analysis. The paper finally discusses a detailed case study of the developed risk assessment methodology performed for a subway construction project in Korea. 相似文献
65.
Sun-Mo Yang Beumjun Ahn Kwang-Kyu Seo 《The International Journal of Advanced Manufacturing Technology》2006,28(9-10):1031-1037
Current Computer integrated manufacturing/Enterprise Resource Planning (CIM/ERP) systems require harmony and communication between humans and facilities. A user’s preferences should also be considered in CIM/ERP systems. Virtual factory (VF), also known as virtual manufacturing (VM), systems can fulfill the requirements of current CIM/ERP systems. A VF system simulates virtual production in a virtual factory environment on the computer system which allows optimization prior to going into production. In this paper, we defined a VF system as a pre-analyzing system for designing, engineering and manufacturing a product in the enterprise system of the real world. The objective of this paper is to design a VF system and to develop a prototype system that the customer can participate in and be satisfied with. We selected a telephone as a sample product for the VF system. The VF system consists of four subsystems: virtual product ordering, design, manufacturing, and CIM/ERP interface. The prototype system aims to develop a virtual product ordering and design system. 相似文献
66.
Young-Soo Seo Weui-Bong Jeong Wan-Suk Yoo Ho-Kyeong Jeong 《Journal of Mechanical Science and Technology》2005,19(2):625-633
A finite element vibration analysis of thin-watled cylindrical shells conveying fluid with uniform velocity is presented The
dynamic behavior of thin-walled shell is based on the Sanders’ theory and the fluid in cyhndrical shell is considered as inviscid
and incompressible so that it satisfies the Laplace’s equation A beam-like shell element is used to reduce the number of degrees-of-freedom
by restricting to the circumferential modes of cylindrical shell An estimation of frequency response function of the pipe
considering of the coupled effects of the internal fluid is presented A dynamic coupling condition of the interface between
the fluid and the structure is used The effective thickness of fluid according to circumferential modes is also discussed
The influence of fluid velocity on the frequency response function is illustrated and discussed The results by this method
are compared with published lesults and those by commercial tools 相似文献
67.
Nak?Yong?KoEmail author Dong?Jin?Seo Koung?Suk?Kim 《Journal of Mechanical Science and Technology》2004,18(1):132-144
This paper presents a new method driving multiple robots to their goal position without collision. To consider the movement
of the robots in a work area, we adopt the concept of avoidability measure. The avoidability measure figures the degree of
how easily a robot can avoid other robots considering the velocity of the robots. To implement the concept to avoid collision
among multiple robots, relative distance between the robots is proposed. The relative distance is a virtual distance between
robots indicating the threat of collision between the robots. Based on the relative distance, the method calculates repulsive
force against a robot from the other robots. Also, attractive force toward the goal position is calculated in terms of the
relative distance. These repulsive force and attractive force are added to form the driving force for robot motion. The proposed
method is simulated for several cases. The results show that the proposed method steers robots to open space anticipating
the approach of other robots. In contrast, since the usual potential field method initiates avoidance motion later than the
proposed method, it sometimes fails preventing collision or causes hasty motion to avoid other robots. The proposed method
works as a local collision-free motion coordination method in conjunction with higher level of task planning and path planning
method for multiple robots to do a collaborative job. 相似文献
68.
This paper deals with verb-verb morphological disambiguation of two different verbs that have the same inflected form. The verb-verb morphological ambiguity (VVMA) is one of the critical Korean parts of speech (POS) tagging issues. The recognition of verb base forms related to ambiguous words highly depends on the lexical information in their surrounding contexts and the domains they occur in. However, current probabilistic morpheme-based POS tagging systems cannot handle VVMA adequately since most of them have a limitation to reflect a broad context of word level, and they are trained on too small amount of labeled training data to represent sufficient lexical information required for VVMA disambiguation.In this study, we suggest a classifier based on a large pool of raw text that contains sufficient lexical information to handle the VVMA. The underlying idea is that we automatically generate the annotated training set applicable to the ambiguity problem such as VVMA resolution via unlabeled unambiguous instances which belong to the same class. This enables to label ambiguous instances with the knowledge that can be induced from unambiguous instances. Since the unambiguous instances have only one label, the automatic generation of their annotated corpus are possible with unlabeled data.In our problem, since all conjugations of irregular verbs do not lead to the spelling changes that cause the VVMA, a training data for the VVMA disambiguation are generated via the instances of unambiguous conjugations related to each possible verb base form of ambiguous words. This approach does not require an additional annotation process for an initial training data set or a selection process for good seeds to iteratively augment a labeling set which are important issues in bootstrapping methods using unlabeled data. Thus, this can be strength against previous related works using unlabeled data. Furthermore, a plenty of confident seeds that are unambiguous and can show enough coverage for learning process are assured as well.We also suggest a strategy to extend the context information incrementally with web counts only to selected test examples that are difficult to predict using the current classifier or that are highly different from the pre-trained data set.As a result, automatic data generation and knowledge acquisition from unlabeled text for the VVMA resolution improved the overall tagging accuracy (token-level) by 0.04%. In practice, 9-10% out of verb-related tagging errors are fixed by the VVMA resolution whose accuracy was about 98% by using the Naïve Bayes classifier coupled with selective web counts. 相似文献
69.
Yongbo Seo Seojung Mo Suhyun Kim Hyun Kim Hae-Chul Park 《International journal of molecular sciences》2022,23(21)
Tamalin is a post-synaptic scaffolding protein that interacts with group 1 metabotropic glutamate receptors (mGluRs) and several other proteins involved in protein trafficking and cytoskeletal events, including neuronal growth and actin reorganization. It plays an important role in synaptic plasticity in vitro by controlling the ligand-dependent trafficking of group 1 mGluRs. Abnormal regulation of mGluRs in the central nervous system (CNS) is associated with glutamate-mediated neurodegenerative disorders. However, the pathological consequences of tamalin deficiency in the CNS are unclear. In this study, tamalin knockout (KO) zebrafish and mice exhibited neurodegeneration along with oligodendrocyte degeneration in the post-embryonic CNS to adulthood without any developmental defects, thus suggesting the function of tamalin is more important in the postnatal stage to adulthood than that in CNS development. Interestingly, hypomyelination was independent of axonal defects in the CNS of tamalin knockout zebrafish and mice. In addition, the loss of Arf6, a downstream signal of tamalin scaffolding protein, synergistically induced neurodegeneration in tamalin KO zebrafish even in the developing CNS. Furthermore, tamalin KO zebrafish displayed increased mGluR5 expression. Taken together, tamalin played an important role in neuronal and oligodendrocyte survival and myelination through the regulation of mGluR5 in the CNS. 相似文献
70.
Jin-Ho Park Eun-Byeol Koh Young-Jin Seo Hye-Seong Oh Ju-Yeong Won Sun-Chul Hwang June-Ho Byun 《International journal of molecular sciences》2022,23(22)
Tiron is a potent antioxidant that counters the pathological effects of reactive oxygen species (ROS) production due to oxidative stress in various cell types. We examined the effects of tiron on mitochondrial function and osteoblastic differentiation in human periosteum-derived cells (hPDCs). Tiron increased mitochondrial activity and decreased senescence-associated β-galactosidase activity in hPDCs; however, it had a detrimental effect on osteoblastic differentiation by reducing alkaline phosphatase (ALP) activity and alizarin red-positive mineralization, regardless of H2O2 treatment. Osteoblast-differentiating hPDCs displayed increased ROS production compared with non-differentiating hPDCs, and treatment with tiron reduced ROS production in the differentiating cells. Antioxidants decreased the rates of oxygen consumption and ATP production, which are increased in hPDCs during osteoblastic differentiation. In addition, treatment with tiron reduced the levels of most mitochondrial proteins, which are increased in hPDCs during culture in osteogenic induction medium. These results suggest that tiron exerts negative effects on the osteoblastic differentiation of hPDCs by causing mitochondrial dysfunction. 相似文献