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Information Center for Mathematical Science

세미나

Information Center for Mathematical Science

세미나

한국고등과학원 세미나

We discuss the super string theory for mathematicians for one semester. We cover 1.Brief review of mechanics(classical and quantum) and field theory(classical and quantum) 2. Bosonic and super string theory 3. D-branes(Dirichlet branes) 4. AdS(anti de Sitter) and CFT(conformal field theory)

한국고등과학원 세미나

We discuss the super string theory for mathematicians for one semester. We cover 1.Brief review of mechanics(classical and quantum) and field theory(classical and quantum) 2. Bosonic and super string theory 3. D-branes(Dirichlet branes) 4. AdS(anti de Sitter) and CFT(conformal field theory)

한국고등과학원 세미나

We discuss the super string theory for mathematicians for one semester. We cover 1.Brief review of mechanics(classical and quantum) and field theory(classical and quantum) 2. Bosonic and super string theory 3. D-branes(Dirichlet branes) 4. AdS(anti de Sitter) and CFT(conformal field theory)

한국고등과학원 세미나

We discuss the super string theory for mathematicians for one semester. We cover 1.Brief review of mechanics(classical and quantum) and field theory(classical and quantum) 2. Bosonic and super string theory 3. D-branes(Dirichlet branes) 4. AdS(anti de Sitter) and CFT(conformal field theory)

한국고등과학원 세미나

We discuss the super string theory for mathematicians for one semester. We cover 1.Brief review of mechanics(classical and quantum) and field theory(classical and quantum) 2. Bosonic and super string theory 3. D-branes(Dirichlet branes) 4. AdS(anti de Sitter) and CFT(conformal field theory)

한국고등과학원 세미나

We discuss the super string theory for mathematicians for one semester. We cover 1.Brief review of mechanics(classical and quantum) and field theory(classical and quantum) 2. Bosonic and super string theory 3. D-branes(Dirichlet branes) 4. AdS(anti de Sitter) and CFT(conformal field theory)

한국고등과학원 세미나

We discuss the super string theory for mathematicians for one semester. We cover 1.Brief review of mechanics(classical and quantum) and field theory(classical and quantum) 2. Bosonic and super string theory 3. D-branes(Dirichlet branes) 4. AdS(anti de Sitter) and CFT(conformal field theory)

한국고등과학원 세미나

We discuss the super string theory for mathematicians for one semester. We cover 1.Brief review of mechanics(classical and quantum) and field theory(classical and quantum) 2. Bosonic and super string theory 3. D-branes(Dirichlet branes) 4. AdS(anti de Sitter) and CFT(conformal field theory)

한국고등과학원 세미나

We discuss the super string theory for mathematicians for one semester. We cover 1.Brief review of mechanics(classical and quantum) and field theory(classical and quantum) 2. Bosonic and super string theory 3. D-branes(Dirichlet branes) 4. AdS(anti de Sitter) and CFT(conformal field theory)

한국고등과학원 세미나

The spherical maximal function is a classical object studied to answer the general question of the differentiability of integral in R^d. In this talk, we observe boundedness properties of the spherical maximal function and its variant formula in the Lebesgue space.

KAIST 수리과학과 세미나

In this talk, I will introduce the idea to study the Noether inequality for 3-folds of general type with the geometric genus less than 21. This is my project working in progress with Bingru Li.

KAIST Discrete Math 세미나

A signed graph is a pair (G, σ), where G is a graph and σ: E(G) → {1,-1} is a signature of G. A set S of integers is symmetric if I∈S implies that -i∈S. A k-colouring of (G,σ) is a mapping f:V(G) → Nk such that for each edge e=uv, f(x)≠σ(e) f(y), where Nk is a symmetric integer set of size k. We define the signed chromatic number of a graph G to be the minimum integer k such that for any signature σ of G, (G, σ) has a k-colouring. Let f(n,k) be the maximum signed chromatic number of an n-vertex k-chromatic graph. This paper determines the value of f(n,k) for all positive integers n ≥ k. Then we study list colouring of signed graphs. A list assignment L of G is called symmetric if L(v) is a symmetric integer set for each vertex v. The weak signed choice number ch±w(G) of a graph G is defined to be the minimum integer k such that for any symmetric k-list assignment L of G, for any signature σ on G, there is a proper L-colouring of (G, σ). We prove that the difference ch±w(G)-χ±(G) can be arbitrarily large. On the other hand, ch±w(G) is bounded from above by twice the list vertex arboricity of G. Using this result, we prove that ch±w(K2⋆n)= χ±(K2⋆n) = ⌈2n/3⌉ + ⌊2n/3⌋. This is joint work with Ringi Kim and Xuding Zhu.

서울대학교 지구환경과학부 세미나
서울대학교 지구환경과학부 세미나
서울대학교 지구환경과학부 세미나

북한의 최근 산업기술 동향을 영상자료를 중심으로 살펴보기로 한다. 이 발표 자료는 두 부분으로 구성된다. 첫째 부분에서는 북한의 산업기술을 대표하는 CNC 기술, 주체철, 탄소하나화학공업 육성, 공장의 통합생산체계 확충 실태를 개관해본다. 둘째로 이러한 산업기술과 관련한 동향을 PPT를 통해 영상자료로 확인하기로 한다. 영상자료는 대부분 조선중앙텔레비전에 방영된 자료를 캡쳐한 것이다. 시간 관계상 인쇄자료에 대한 상세한 언급은 지양하고, 북한의 산업기술과 관련한 최근 영상자료들을 소개하는 데 중점을 둘 예정이다.

서울대학교 지구환경과학부 세미나

Oxygen (16O, 17O and 18O) and sulfur (32S, 33S, 34S and 36S) isotope ratios of and major ion (Na+, Ca2+, Cl-, NO3- and SO42-) concentrations in lakes, ponds and creeks from Deception Island, Antarctic Peninsula were analyzed to study the sources of sulfate, its oxidation, and the surficial processes of the dissolved sulfate. The positive relationship between the δ34Ssulfate (8.1 ‰ to 17.3 ‰) and the Cl-/SO42- molar ratio suggests mixing of sulfate from atmospheric deposition and from oxidation of sulfide minerals. The average sea salt fraction (28 %) and δ34Snss values (from 5.6 ‰ to 15.9 ‰) indicate that a combination of sea salt and marine biogenic sulfide provide the high δ34S end-member of the dissolved sulfates. The relatively low δ18Osulfate (from -4.6 ‰ to 0.7 ‰) of Deception Island water suggests a role of local water in the formation of sulfate. Slightly negative but mass-dependent Δ17Osulfate values imply that atmospheric oxidation by O3 and H2O2 are negligible, while these values might suggest a significant role of oxidation by molecular oxygen and •OH. The distinctly low δ34Ssulfate value of two samples suggests the input of sulfate from sulfide oxidation. Slight elevation of δ34Ssulfate values up to 17.3 ‰ compared to a typical atmospheric value indicates a minimal role for dissimilatory microbial sulfate reduction of Deception Island water and sediments. Both Δ33Ssulfate and Δ36Ssulfate values are homogeneous and near zero, implying that the dominant atmospheric oxidation process is tropospheric and that there are minimal to no contributions of stratospheric sulfate to Deception Island water.

한국천문연구원 콜로퀴움

First of all, I shall give an overview on the research status about stellar magnetic activity and exoplanetary systems at Yunnan Observatories. Then, some more detailed results derived during recent years will be introduced. For stellar activity, I shall talk about the study on chromospheric and photospheric activities by using high-resolution spectroscopy, magnetic field by using Zeeman Doppler imaging method. For exoplanetary systems, I shall talk about the study on wide field transit survey project, TTV follow-up observations. Finally, the prospects in the near future will be given.

한국천문연구원 콜로퀴움

The ground-based photometric observations of asteroids still is the main source to understand their basic physical properties, even though some space mission and space-based instruments have been applied in physical studies of asteroids. With the help of developments on scattering theories and 3D shape models of asteroid, more and more asteroids are studies their basic physical parameters of asteroids from the photometric data. In this presentation, I will present photometric studies for some selected asteroids. In detail, they are: (1)To determine photometric phase functions of asteroids (107) Camilla and (106) Dione assuming an ellipsoid shape and a cellinoid shape respectively; and (2) To inverse convex shape of main-belt slow rotating asteroids (168) Sibylla and (346)Hermentaria and a near Earth asteroid (3200) Phaethon. Based on derived photometric phase functions, the geometric albedo, and even rough taxonomic classification of asteroids are inferred. With the virtual photometry Monta Carlo method, the uncertainties of spin parameters of selected asteroids were compared.

2018 KAIST Physics Seminar

In this work, we investigated theoretically the Mott-insulating phase of a deficient spinel chalcogenide GaV4S8, which is known to form a tetrahedral V_4 S_4 cluster unit that results in molecular orbitals (MOs) with a narrow bandwidth in the noninteracting limit. We used a cluster extension of charge self-consistent embedded dynamical mean-field theory to study the impact of strong intra-cluster correlations on the spectral properties as well as the structural degrees of freedom of the system. We found that the strong tetrahedral clustering renders the atomic Mott picture ineffective, and that the resulting MO picture is essential to describe the Mott phase. It was also found that, while the spectral properties can be qualitatively described by the truncation of the Hilbert space down to the lowest-energy MO, a proper description of the structural degrees of freedom requires the inclusion of multi-MO correlations that span a larger energy window. Specifically, we found that the lowest-energy MO description overemphasizes the clustering tendency, while the inclusion of the Hund's coupling between the lower- and higher-energy MOs corrects this tendency, bringing the theoretically predicted crystal structure into good agreement with the experiment.

2018 KAIST Physics Seminar

We propose many-body invariants for multipoles in higher-order topological insulators by generalizing Resta's pioneering work on polarization. The many-body invariants are designed to measure multipolar charge distribution in a crystalline unit cell, and they match the localized corner charge originating from the multipoles. We provide analytic arguments and numerical proof for the invariants. Furthermore, we show that the many-body invariants faithfully measure the physical multipole moments even when the nested Wilson loop approaches fail to do so