A simple proof of ill-posedness for incompressible Euler equations in critical Sobolev spaces

We provide a simple proof that the Cauchy problem for the incompressible Euler equations in $\mathbb{R}^{d}$ with any $d\ge3$ is ill-posed in critical Sobolev spaces, extending an earlier work of Bourgain and Li in the case $d = 3$. The ill-posedness is shown for certain critical Lorentz spaces as well.Comment: To appear in J. Funct. Ana

Development of Ocean Economy Satellite Account in Korea

The ocean has emerged as a new solution to new growth engines. However, some issues remain to be resolved, such as unified concepts and evaluation methods for the ocean economy, comparability between the national economy and the ocean economy, and the connection between global and national assessments. Since the ocean economy comprises various complex industries, it is necessary to establish policies based on an objective analysis of economic indicators. However, there have been difficulties in analyzing industrial activities related to the ocean economy within the national account system. To more accurately calculate the share of the ocean economy sector in the national economy, it is necessary to create a satellite account that reflects the characteristics of the ocean economic activities while maintaining consistency with the national account. This study aims to develop a satellite account for the ocean economy, a measurement of GDP in the ocean sector, which can correspond with the national accounts system and intends to propose Korean practices as a framework in the process of discussing international guidelines. This study introduces a potential structure for Korea\u27s ocean economy satellite account, the principles, methods, and data used for value coefficient estimation, and finally presents pilot results for several components of the ocean economy. This account can be utilized to diagnose the economic position as well as the policy effects of Korea’s ocean economy sector while contributing to the establishment of mid-to-long term industrial policies. This case study of Korean practices can be an important example that offers a framework and principles for international discussions

Two-dimensional Dirac plasmon-polaritons in graphene, 3D topological insulator and hybrid systems

Collective oscillations of massless particles in two-dimensional (2D) Dirac materials offer an innovative route toward implementing atomically thin devices based on low-energy quasiparticle interactions. Strong confinement of near-field distribution on the 2D surface is essential to demonstrate extraordinary optoelectronic functions, providing means to shape the spectral response at the mid-infrared (IR) wavelength. Although the dynamic polarization from the linear response theory has successfully accounted for a range of experimental observations, a unified perspective was still elusive, connecting the state-of-the-art developments based on the 2D Dirac plasmon-polaritons. Here, we review recent works on graphene and three-dimensional (3D) topological insulator (TI) plasmon-polariton, where the mid-IR and terahertz (THz) radiation experiences prominent confinement into a deep-subwavelength scale in a novel optoelectronic structure. After presenting general light-matter interactions between 2D Dirac plasmon and subwavelength quasiparticle excitations, we introduce various experimental techniques to couple the plasmon-polaritons with electromagnetic radiations. Electrical and optical controls over the plasmonic excitations reveal the hybridized plasmon modes in graphene and 3D TI, demonstrating an intense near-field interaction of 2D Dirac plasmon within the highly-compressed volume. These findings can further be applied to invent optoelectronic bio-molecular sensors, atomically thin photodetectors, and laser-driven light sources

Fermentation characteristics of Korean pear (Pyrus pyrifolia Nakai) puree by the Leuconostoc mesenteroides 51-3 strain isolated from Kimchi

A lactic acid bacterial strain showing fast growth and high acid production when cultured in Korean pear puree was isolated from Kimchi. This strain was analyzed by using the API 50 CHL kit and 16S rRNA sequencing and was thus identified as Leuconostoc mesenteroides 51-3. Korean pear puree was fermented with the L. mesenteroides 51-3 strain at 30°C for 12 h. The changes in pH, titratable acidity and viable cell count during fermentation were investigated. The pH and titratable acidity of the pear puree were 4.06 and 0.66%, respectively, after 12 h of fermentation. The viable cell count of L. mesenteroides 51-3 rapidly increased to 3.7 × 109 CFU/g after 12 h of cultivation. The content of lactic acid and acetic acid was determined to be 0.138 and 0.162%, respectively, after 12 h of fermentation. When the fermented pear puree was stored at 4°C, the pH, titratable acidity and viable cell count remained fairly constant for 14 days.Keywords: Fermentation, Korean pear puree, Leuconostoc mesenteroides.African Journal of Biotechnology Vol. 9(35), pp. 5735-5738, 30 August, 201

Improving the Expressiveness of Deep Learning Frameworks with Recursion

Recursive neural networks have widely been used by researchers to handle applications with recursively or hierarchically structured data. However, embedded control flow deep learning frameworks such as TensorFlow, Theano, Caffe2, and MXNet fail to efficiently represent and execute such neural networks, due to lack of support for recursion. In this paper, we add recursion to the programming model of existing frameworks by complementing their design with recursive execution of dataflow graphs as well as additional APIs for recursive definitions. Unlike iterative implementations, which can only understand the topological index of each node in recursive data structures, our recursive implementation is able to exploit the recursive relationships between nodes for efficient execution based on parallel computation. We present an implementation on TensorFlow and evaluation results with various recursive neural network models, showing that our recursive implementation not only conveys the recursive nature of recursive neural networks better than other implementations, but also uses given resources more effectively to reduce training and inference time.Comment: Appeared in EuroSys 2018. 13 pages, 11 figure

Concerning the Mismatch of Particle wa and Korean nun/un

Korean and Japanese have in common the grammatical category of case markers. Thus, in the case of native Korean learners of the Japanese language and the native Japanese learners of the Korean language, the effectiveness of second language learning is in general high. However, the usage of the case markers in the two languages is not always identical. We can see various cases of non－correspondence in the use of the case markers in the two languages. Although the postpositional markers wa and nun/un correspond to each other in many areas, there are some areas in which wa and nun/un do not correspond: one remarkable mismatch is observed in WH－questions. In this paper, we observe two phenomena in WH－question sentences. First, in the case where the noun phrase (NP) or the pronoun in sentence initial position has neither determiner nor modifying phrase, nominative marker ka/i is used in Korean, whereas wa is used in Japanese. Second, in the case where the NP has a determiner or modifying phrase, the marker in the Korean sentences which corresponds to wa in the corresponding Japanese sentence can be nun/un. The explanation lies in that the determiner or modifying phrase set the limit of the NP. In other words, whereas wa can occur when the NP in WH－questions are not limited, nun in Korean cannot. Unlike wa, nun/un in Korean always requires some kind of limitation.論