Gwak Cheol-Kwang
Ewha Womans University · Mathematics
About the Lab
Professor Gwak Cheol-Kwang's research focuses on nonlinear dispersive partial differential equations, particularly higher-order Korteweg–de Vries (KdV) and modified KdV equations, in periodic and non-periodic settings. His work centers on the well-posedness theory—especially local and global well-posedness—in low regularity Sobolev spaces, employing advanced tools such as the short-time Fourier restriction norm method and frequency-localized energy estimates. He investigates the interplay between integrability, resonance structures, and smoothing effects in periodic domains, where the absence of standard smoothing complicates analysis. His research contributes significantly to understanding the dynamics of shallow water waves and related Hamiltonian systems.
Research Overview
Research Output Trend
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Selected Papers
15We consider the fifth-order modified Korteweg–de Vries (modified KdV) equation under the periodic boundary condition. We prove the local well-posedness in [Formula: see text], [Formula: see text], via the energy method. The main tool is the short-time Fourier restriction norm method, which was first introduced in its current form by Ionescu, Kenig and Tataru [Global well-posedness of the KP-I initial-value problem in the energy space, Invent. Math. 173(2) (2008) 265–304]. Besides, we use the fre
Consider the Hamiltonian <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" alttext="a b c d"> <mml:semantics> <mml:mrow> <mml:mi>a</mml:mi> <mml:mi>b</mml:mi> <mml:mi>c</mml:mi> <mml:mi>d</mml:mi> </mml:mrow> <mml:annotation encoding="application/x-tex">abcd</mml:annotation> </mml:semantics> </mml:math> </inline-formula> system in one dimension, with data posed in the energy space <inline-formula content-type="math/mathml"> <mml:math xmlns:mml="
This paper is concerned with the Cauchy problem of the modified Kawahara equation (posed on \mathbb{T} ), which is well-known as a model of capillary-gravity waves in an infinitely long canal over a flat bottom in a long wave regime [26]. We show in this paper some well-posedness results, mainly the global well-posedness in L^{2}(\mathbb{T}) . The proof basically relies on the idea introduced in Takaoka-Tsutsumi's works [60,69], which weakens the non-trivial resonance in the cubic interactions (
The Boussinesq $abcd$ system is a 4-parameter set of equations posed in $\mathbb{R}_t \times \mathbb{R}_x$, originally derived by Bona, Chen and Saut as first order 2-wave approximations of the incompressible and irrotational, two dimensional water wave equations in the shallow water wave regime, in the spirit of the original Boussinesq derivation. Among many particular regimes, depending each of them in terms of the value of the parameters $(a,b,c,d)$ present in the equations, the "generic" reg
We consider the Cauchy problem for the fifth-order modified Korteweg-de Vries equation (mKdV) on $ \mathbb T $. The fifth-order mKdV is an asymptotic model for shallow surface waves, as is the second equation in the mKdV hierarchy. In contrast with the non-periodic case, periodic solutions for dispersive equations do not have a (local) smoothing effect, which becomes a major obstacle to considering the Cauchy problem for dispersive equations on $ \mathbb T $.We establish global well-posedness of
This paper is a continuation of the paper \emph{Low regularity Cauchy problem for the fifth-order modified KdV equations on $\mathbb{T}$}. In this paper, we consider the fifth-order equation in the Korteweg-de Vries (KdV) hierarchy as following: \begin{equation*} \begin{cases} \partial_t u - \partial_x^5 u + 30u^2\partial_x u + 20 u\partial_x u \partial_x^3u + 10u \partial_x^3 u = 0, \hspace{1em} (t,x) \in \mathbb{R} \times \mathbb{T}, u(0,x) = u_0(x) \in H^s(\mathbb{T}) \end{cases}. \end{equati
In this paper, we consider the fifth-order modified Korteweg-de Vries (modified KdV) equation under the periodic boundary condition. We prove the local well-posedness in $H^s(\mathbb T)$, $s > 2$, via the energy method. The main tool is the short-time Fourier restriction norm method, which was first introduced in its current form by Ionescu, Kenig and Tataru [Global well-posedness of the KP-I initial-value problem in the energy space, Invent. Math. 173 (2) (2008) 265--304]. Besides, we use th
We consider the Cauchy problem for the fifth-order modified Korteweg-de Vries equation (mKdV) under the periodic boundary condition. The fifth-order mKdV is an asymptotic model for shallow surface waves, and (in the perspective of integrable systems) the second equation in the mKdV hierarchy as well. In strong contrast with the non-periodic case, periodic solutions for dispersive equations do not have a (local) smoothing effect, and this observation becomes a major obstacle to considering the Ca
Research Areas
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