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2,158 results on '"Kim, Jaehoon"'

201. On the number of $r$-matchings in a Tree

Author

Kang, Dong Yeap, Kim, Jaehoon, Kim, Younjin, and Law, Hiu-Fai

Subjects
Mathematics - Combinatorics
Abstract

An $r$-matching in a graph $G$ is a collection of edges in $G$ such that the distance between any two edges is at least $r$. A $2$-matching is also called an induced matching. In this paper, we estimate the maximum number of $r$-matchings in a tree of fixed order. We also prove that the $n$-vertex path has the maximum number of induced matchings among all $n$-vertex trees.

Published
2014

202. On the Erdos-Ko-Rado Theorem and the Bollobas Theorem for t-intersecting families

Author

Kang, Dong Yeap, Kim, Jaehoon, and Kim, Younjin

Subjects
Mathematics - Combinatorics
Abstract

A family $\mathcal{F}$ is $t$-$\it{intersecting}$ if any two members have at least $t$ common elements. Erd\H os, Ko, and Rado proved that the maximum size of a $t$-intersecting family of subsets of size $k$ is equal to $ {{n-t} \choose {k-t}}$ if $n\geq n_0(k,t)$. Alon, Aydinian, and Huang considered families generalizing intersecting families, and proved the same bound. In this paper, we give a strengthening of their result by considering families generalizing $t$-intersecting families for all $t \geq 1$. In 2004, Talbot generalized Bollob\'{a}s's Two Families Theorem to $t$-intersecting families. In this paper, we proved a slight generalization of Talbot's result by using the probabilistic method.

Published
2014

203. A relative of Hadwiger's conjecture

Author

Edwards, Katherine, Kang, Dong Yeap, Kim, Jaehoon, Oum, Sang-il, and Seymour, Paul

Subjects
Mathematics - Combinatorics, 05C83, 05C15
Abstract

Hadwiger's conjecture asserts that if a simple graph $G$ has no $K_{t+1}$ minor, then its vertex set $V(G)$ can be partitioned into $t$ stable sets. This is still open, but we prove under the same hypotheses that $V(G)$ can be partitioned into $t$ sets $X_1,\ldots, X_t$, such that for $1\le i\le t$, the subgraph induced on $X_i$ has maximum degree at most a function of $t$. This is sharp, in that the conclusion becomes false if we ask for a partition into $t-1$ sets with the same property., Comment: 6 pages

Published
2014
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207. Advances in molecular quantum chemistry contained in the Q-Chem 4 program package

Author

Shao, Yihan, Gan, Zhengting, Epifanovsky, Evgeny, Gilbert, Andrew TB, Wormit, Michael, Kussmann, Joerg, Lange, Adrian W, Behn, Andrew, Deng, Jia, Feng, Xintian, Ghosh, Debashree, Goldey, Matthew, Horn, Paul R, Jacobson, Leif D, Kaliman, Ilya, Khaliullin, Rustam Z, Kuś, Tomasz, Landau, Arie, Liu, Jie, Proynov, Emil I, Rhee, Young Min, Richard, Ryan M, Rohrdanz, Mary A, Steele, Ryan P, Sundstrom, Eric J, Woodcock, H Lee, Zimmerman, Paul M, Zuev, Dmitry, Albrecht, Ben, Alguire, Ethan, Austin, Brian, Beran, Gregory JO, Bernard, Yves A, Berquist, Eric, Brandhorst, Kai, Bravaya, Ksenia B, Brown, Shawn T, Casanova, David, Chang, Chun-Min, Chen, Yunqing, Chien, Siu Hung, Closser, Kristina D, Crittenden, Deborah L, Diedenhofen, Michael, DiStasio, Robert A, Do, Hainam, Dutoi, Anthony D, Edgar, Richard G, Fatehi, Shervin, Fusti-Molnar, Laszlo, Ghysels, An, Golubeva-Zadorozhnaya, Anna, Gomes, Joseph, Hanson-Heine, Magnus WD, Harbach, Philipp HP, Hauser, Andreas W, Hohenstein, Edward G, Holden, Zachary C, Jagau, Thomas-C, Ji, Hyunjun, Kaduk, Benjamin, Khistyaev, Kirill, Kim, Jaehoon, Kim, Jihan, King, Rollin A, Klunzinger, Phil, Kosenkov, Dmytro, Kowalczyk, Tim, Krauter, Caroline M, Lao, Ka Un, Laurent, Adèle D, Lawler, Keith V, Levchenko, Sergey V, Lin, Ching Yeh, Liu, Fenglai, Livshits, Ester, Lochan, Rohini C, Luenser, Arne, Manohar, Prashant, Manzer, Samuel F, Mao, Shan-Ping, Mardirossian, Narbe, Marenich, Aleksandr V, Maurer, Simon A, Mayhall, Nicholas J, Neuscamman, Eric, Oana, C Melania, Olivares-Amaya, Roberto, O’Neill, Darragh P, Parkhill, John A, Perrine, Trilisa M, Peverati, Roberto, Prociuk, Alexander, Rehn, Dirk R, Rosta, Edina, Russ, Nicholas J, Sharada, Shaama M, Sharma, Sandeep, Small, David W, and Sodt, Alexander

Subjects
Chemical Sciences, Physical Chemistry, Theoretical and Computational Chemistry, quantum chemistry, electron correlation, electronic structure theory, Q-Chem, computational modelling, software, density functional theory, Atomic, Molecular, Nuclear, Particle and Plasma Physics, Physical Chemistry (incl. Structural), Chemical Physics, Physical chemistry, Theoretical and computational chemistry
Abstract

A summary of the technical advances that are incorporated in the fourth major release of the Q-Chem quantum chemistry program is provided, covering approximately the last seven years. These include developments in density functional theory methods and algorithms, nuclear magnetic resonance (NMR) property evaluation, coupled cluster and perturbation theories, methods for electronically excited and open-shell species, tools for treating extended environments, algorithms for walking on potential surfaces, analysis tools, energy and electron transfer modelling, parallel computing capabilities, and graphical user interfaces. In addition, a selection of example case studies that illustrate these capabilities is given. These include extensive benchmarks of the comparative accuracy of modern density functionals for bonded and non-bonded interactions, tests of attenuated second order Møller-Plesset (MP2) methods for intermolecular interactions, a variety of parallel performance benchmarks, and tests of the accuracy of implicit solvation models. Some specific chemical examples include calculations on the strongly correlated Cr2 dimer, exploring zeolite-catalysed ethane dehydrogenation, energy decomposition analysis of a charged ter-molecular complex arising from glycerol photoionisation, and natural transition orbitals for a Frenkel exciton state in a nine-unit model of a self-assembling nanotube.

Published
2015

217. Harmonious Coloring of Trees with Large Maximum Degree

Author

Akbari, Saieed, Kim, Jaehoon, and Kostochka, Alexandr

Subjects
Mathematics - Combinatorics, Computer Science - Discrete Mathematics
Abstract

A harmonious coloring of $G$ is a proper vertex coloring of $G$ such that every pair of colors appears on at most one pair of adjacent vertices. The harmonious chromatic number of $G$, $h(G)$, is the minimum number of colors needed for a harmonious coloring of $G$. We show that if $T$ is a forest of order $n$ with maximum degree $\Delta(T)\geq \frac{n+2}{3}$, then $$h(T)= \Delta(T)+2, & if $T$ has non-adjacent vertices of degree $\Delta(T)$; \Delta(T)+1, & otherwise. $$ Moreover, the proof yields a polynomial-time algorithm for an optimal harmonious coloring of such a forest., Comment: 8 pages, 1 figure

Published
2012

218. Enhancing Selectivity in 5G/6G Ultranarrowband Applications: Plug-and-Play Frequency-Selective Surfaces With Field-Manipulating Vias

Author

Kim, Jaehoon, Bang, Seungwoo, Jeong, Jungi, Wi, Sang-Hyuk, and Oh, Jungsuek

Abstract

This study presents unmatchedly selective ultranarrowband frequency-selective surfaces (FSSs) for a pioneering external RF front-end (RFFE) filtering solution integrated with diverse beamforming antenna modules. The limitations of current base station filters for 28 GHz are demonstrated, and an inventive approach that extends the boundaries of the filtering block by positioning it outside the RFFE for spatial reinforcement is newly devised. An innovative analysis of narrow-bandpass complementary resonator pairs is introduced, unlocking unprecedented selectivity by addressing the challenging issue of recalcitrant mutual coupling arising from a dispersive field distribution. This spatial methodology extends the frontier by seamlessly integrating field analysis with a mixed coupling theory previously established in the circuit domain. Subsequently, a trailblazing technique is proposed for precise control of coupling balance, utilizing field-manipulating vias to centralize the primary current in the complementary resonator. This approach achieves an average rejection of 60 dB across the stopband, ensuring robust stability for incident angles up to 70°, surpassing previous counterparts. Furthermore, it demonstrates a significantly improved roll-off in the transition band and achieves a remarkable 2.7% bandwidth (BW), comparable to the 850 MHz for the n261 band of 5G NR.

Published
2024
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219. New results in $t$-tone coloring of graphs

Author

Cranston, Daniel W., Kim, Jaehoon, and Kinnersley, William B.

Subjects
Mathematics - Combinatorics
Abstract

A $t$-tone $k$-coloring of $G$ assigns to each vertex of $G$ a set of $t$ colors from $\{1,..., k\}$ so that vertices at distance $d$ share fewer than $d$ common colors. The {\it $t$-tone chromatic number} of $G$, denoted $\tau_t(G)$, is the minimum $k$ such that $G$ has a $t$-tone $k$-coloring. Bickle and Phillips showed that always $\tau_2(G) \le [\Delta(G)]^2 + \Delta(G)$, but conjectured that in fact $\tau_2(G) \le 2\Delta(G) + 2$; we confirm this conjecture when $\Delta(G) \le 3$ and also show that always $\tau_2(G) \le \ceil{(2 + \sqrt{2})\Delta(G)}$. For general $t$ we prove that $\tau_t(G) \le (t^2+t)\Delta(G)$. Finally, for each $t\ge 2$ we show that there exist constants $c_1$ and $c_2$ such that for every tree $T$ we have $c_1 \sqrt{\Delta(T)} \le \tau_t(T) \le c_2\sqrt{\Delta(T)}$., Comment: 13 pages, 1 figure

Published
2011

220. Highly reproducible synthesis of boron arsenide with high thermal conductivity.

Author

Lee, Dongwook, Kim, Jaehoon, and Kang, Joon Sang

Subjects
*THERMAL conductivity, *THERMAL conductivity measurement, *ARSENIDES, *BORON, *CATALYST synthesis, *RAMAN spectroscopy
Abstract

Cubic boron arsenide (BAs) is a subject of considerable interest in thermal science due to its exceptionally high thermal conductivity. However, the inherent long mean free path of phonons renders the thermal conductivity of BAs highly susceptible to impurity concentration. In this study, we present a catalyst assisted crystal synthesis approach to achieve high-quality cubic BAs, leveraging Pt as a catalyst in the synthesis process. Our thermal conductivity measurements reveal that over 90% of the samples in a batch exhibit thermal conductivity values exceeding 1000 W·m−1·K−1. The robustness of the synthesis method is further validated through thermal conductivity mapping and Raman spectroscopy. These findings offer valuable insights for enhancing the quality of BAs crystals and hold promise for practical applications. [ABSTRACT FROM AUTHOR]

Published
2024
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222. On a rainbow extremal problem for color‐critical graphs.

Author

Chakraborti, Debsoumya, Kim, Jaehoon, Lee, Hyunwoo, Liu, Hong, and Seo, Jaehyeon

Subjects
RAINBOWS, LOGICAL prediction, BIPARTITE graphs, EXTREMAL problems (Mathematics)
Abstract

Given k$$ k $$ graphs G1,...,Gk$$ {G}_1,\dots, {G}_k $$ over a common vertex set of size n$$ n $$, what is the maximum value of ∑i∈[k]e(Gi)$$ {\sum}_{i\in \left[k\right]}e\left({G}_i\right) $$ having no "colorful" copy of H$$ H $$, that is, a copy of H$$ H $$ containing at most one edge from each Gi$$ {G}_i $$? Keevash, Saks, Sudakov, and Verstraëte denoted this number as exk(n,H)$$ {\mathrm{ex}}_k\left(n,H\right) $$ and completely determined exk(n,Kr)$$ {\mathrm{ex}}_k\left(n,{K}_r\right) $$ for large n$$ n $$. In fact, they showed that, depending on the value of k$$ k $$, one of the two natural constructions is always the extremal construction. Moreover, they conjectured that the same holds for every color‐critical graphs, and proved it for 3‐color‐critical graphs. They also asked to classify the graphs H$$ H $$ that have only these two extremal constructions. We prove their conjecture for 4‐color‐critical graphs and for almost all r$$ r $$‐color‐critical graphs when r>4$$ r>4 $$. Moreover, we show that for every non‐color‐critical non‐bipartite graphs, none of the two natural constructions is extremal for certain values of k$$ k $$. [ABSTRACT FROM AUTHOR]

Published
2024
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