Jongrak Lee 

Position 

         Associate Professor, Department of Mathematics, Sungkyunkwan University

Employment

• Post-Doc, Sungkyunkwan University, Nov. 2014 - Nov. 2015

• Research Fellow, Ewha Womans University, Dec. 2015 - Feb. 2020

• Assistant Professor, Jeju National University, Mar. 2020 - Feb. 2022

• Assistant Professor, Sungkyunkwan University, Feb. 2022 - Aug. 2024

• Associate Professor, Sungkyunkwan University, Sep. 2024 - Present.

Education

• Ph.D. in Mathematics, Sungkyunkwan University, Aug. 2014

• M.A. in Mathematics, Sungkyunkwan University, Feb. 2007

• B.S. in Mathematics, Sungkyunkwan University, Feb. 2005

Publications

2025

• (with E. Ko, J.E. Lee) Hyponormality of Toeplitz operators on Newton spaces. Ann. Funct. Anal. 16 (2025), no. 3, Paper No. 40.

• (with C. Benhida, G. R. Exner, J. E. Lee)  Toeplitz operators on several function spaces: decompositions yielding subnormality. Banach J. Math. Anal. 19 (2025), no. 3, Paper No. 33, 27 pp.

2024

• (with S. Kim) A sufficient condition for hyponormal Toeplitz operators on the Bergman space. Bull. Korean Math. Soc. 61 (2024). no. 4.

• (with S. Kim, E. Ko, J.E. Lee) H-Toeplitz operators on the function spaces. Monatsh. Math. (2024).

• (with S. Kim) Toeplitz operators with monomial symbols on the Dirichlet spaces. Ann. Funct. Anal. 15 (2024), no. 3, Paper No. 46.

• (with E. Ko, J.E. Lee) Expansivity and contractivity of Toeplitz operators on Newton spaces. Mediterr. J. Math. 21 (2024), no. 2, Paper No. 57, 21 pp.

• (with E. Ko, J.E. Lee) Matrix representation of Toeplitz operators on Newton spaces. J. Inequal. Appl.(2024), Paper No. 43.

2023

• (with S. Kim) Remarks on hyponormal Toeplitz operators with nonharmonic symbols. Open Math. 21 (2023) 8pp

• A remark on hyponormality of block Toeplitz operators on the weighted Bergman spaces. Complex Anal. Oper. Theory 17 (2023) 13pp

• (with E. Ko, J.E. Lee) Properties of Newton polynomials and Toeplitz operators on Newton spaces. submitted. Ann. Funct. Anal. 14 (2023) 14pp

• (with S. Kim) Hyponormal Toeplitz operators with non‑harmonic symbols on the weighted Bergman spaces.  Ann. Funct. Anal. 14 (2023), 14pp

• (with E. Ko, J.E. Lee) Hyponormal Toeplitz operators with non-harmonic symbols on the generalized derivative Hardy spaces. Mediterr. J. Math. 20, 1 (2023)

2022

• (with E. Ko, J.E. Lee) Remarks on Composition operators on the Newton space. Mediterr. J. Math. 19, 205 (2022) 17pp.

• (with E. Ko, J.E. Lee) Complex symmetric Toeplitz operators on the weighted Bergman space. Complex Var. Elliptic Equ. 67 (2022), no. 6, 1398-1408. 

• (with S. Kim) Contractivity and expansivity of H-Toeplitz operators on the Bergman spaces. AIMS Math. 7 (2022), no. 8, 13927–13944. 

• (with E. Ko, J.E. Lee) Complex symmetric Toeplitz operators on the generalized derivative Hardy space. J. Inequal. Appl. 2022, Paper No. 74, 12 pp. 

• (with Y.-H. Kim, J.-M. Kim, S. Andrea) On multiple solutions to a non-local Fractional $p(\cdot)$-Laplacian problem with concave-convex nonlinearities. Adv. Contin. Discrete Models 2022, Paper No. 14, 25pp.

• (with E. Ko, J.E. Lee) Conjugations and complex symmetric block Toeplitz operators on the weighted Hardy space. RACSAM 116, 18 (2022) 15pp.

2021

• (with Y.-H. Kim, K. Ho) Schr\"{o}dinger $p(\cdot)$-Laplace equations in $\mathbb{R}^N$ involving indefinite weights and critical growth. J. Math. Phys, 62 (2021) no. 11, 28pp.

• (with E. Ko, J.E. Lee) Conjugations and complex symmetric Toeplitz operators on the weighted Hardy space. Mediterr. J. Math. 18, 125 (2021) 11pp.

• (with S. Kim) Hyponormality of Toeplitz operators with non-harmonic symbols on the Bergman spaces. J. Inequal. Appl. (2021), 2021:67.

2020

• (with Y.-H. Kim, J.-M. Kim) Radially symmetric solutions for quasilinear elliptic equations involving nonhomogeneous operators on an Orlicz-Sobolev space setting. Acta Math. Sci. 40 (2020), no. 6, 1679-1699. 

• (with E. Ko) Remarks on Hyponormal Toeplitz Operators on the Weighted Bergman Spaces. Complex Anal. Oper, Theory (2020), no. 14;83, 19pp.

• Normal Toeplitz operators on the Fock spaces. Symmetry 2020, 12(10), 1615. 

• (with S. Kim) Normal Toeplitz operators on the Bergman space. Mathematics 2020, 8(9), 1463. 

• (with Y.-H. Kim, J.-M. Kim, J.I. Lee) Multiplicity of weak solutions to non-local elliptic equations involving the fractional p(x)-Laplacian. J. Math. Phys, 61. (2020) 

• (with Y.-H. Kim, J.I. Lee) Existence of Small-Energy Solutions to Nonlocal Schrödinger-Type Equations for Integrodifferential Operators in R^N. Symmetry 2020, 12, 5. 

2019

• (with E. Ko, J.E. Lee) Multiplication and Toeplitz Operators on the Generalized Derivative Hardy Space. Complex Anal. Oper, Theory (2019), no. 13, 4143–4164. 

• (with E. Ko) Hyponormality of Toeplitz operators on the Fock spaces. Complex Var. Elliptic Equ. 64 (2019), no. 11, 1825–1843. 

• (with Y.-H. Kim, J.-M. Kim) Existence of weak solutions to a class of Schr\"{o}dinger type equations involving the fractional p-Laplacian in R^N. J. Korean Math. Soc. 2019 Vol. 56, No. 5. 

• Hyponormality of Toeplitz operators on the weighted Bergman space with matrix-valued circulant symbols. Linear Algebra Appl. 576 (2019), 35–50. 

• (with J.-H. Bae, J.-M. Kim, K. Park) Existence of nontrivial weak solutions for p-biharmonic Kirchhoff-type equations. Bound. Value Probl. 2019:125 (2019), 

• (with E. Ko) m-isometric block Toeplitz operators. J. Inequal. Appl. 2019, 2019:185. 

• (with E. Ko, N. Takahiko, Y. Kim) Hyponormality of singular Cauchy integral operators with matrix-valued symbols. Hokkaido Math. J. 48 (2019), no. 2, 443–459. 

• (with Y.-H. Kim, J.-M. Kim) Existence and multiplicity of solutions for Kirchhoff-Schr\"{o}dinger type equations involving p(x)-Laplacian on the entire space $\Bbb R^{N}$, Nonlinear Anal. Real World Appl., 45 (2019), 620–649. 

2018

• (with Y.-H. Kim, J.-M. Kim) Multiplicity of Small or Large Energy Solutions for Kirchhoff–Schrödinger-Type Equations Involving the Fractional p-Laplacian in R^N, Symmetry 2018, 10(10), 436 

• (with Y.-H. Kim, J.-M. Kim) Existence and multiplicity of solutions for equations of p(x)-Laplace type in R^N without AR-condition. Differential and Integral Equations. 31, number 5-6 (2018), 435-464. Differential and Integral Equations 

• (with E. Ko) On m-isometric Toeplitz operators. Bull. Korean Math. Soc. 55 (2018), 367-378. 

• (with J.-H. Bae, J.-M. Kim, K. Park) Existence of nontrivial weak solutions for a quasilinear Choquard equation. J. Inequal. Appl. 2018, 2018:42. 

2017

• Hyponormality of block Toeplitz operators on the weighted Bergman spaces. Acta Math. Sci. 37 (2017), no. 6, 1695-1704. 

• (with Y.-H. Kim, J.-H. Kim) The existence of infinitely many solutions for nonlinear elliptic equations involving p-Laplace type operators in R^N. J. Nonlinear Sci. Appl. 10 (2017), 2144–2161. 

2016

• (with Y.-H. Kim) Multiplicity results for nonlinear Neumann boundary value problems involving p–Laplace type operators. Bound. Value Probl. 2016:95 (2016), 25 pp. 

• (with I.S. Hwang, A.H. Kim) A subnormal Toeplitz completion. Oper. Matrices 10(1) (2016), 29–43. 

2014

• (with I.S. Hwang, S.W. Park) Hyponormal Toeplitz operators with polynomial symbols on weighted Bergman spaces. J. Inequal. Appl. 2014:335 (2014), 8 pp. 

2012

• (with I.S. Hwang) Hyponormal Toeplitz operators on the weighted Bergman spaces. Math. Inequal. Appl. 15 (2012), 323–330. 

2007

• (with I.S. Hwang) Hyponormal Toeplitz operators on the Bergman space. II. Bull. Korean Math. Soc. 44 (2007), 517–522. 

Funds

• NRF(2018~2021) 2018R1D1A1B07048620

• NRF(2021~2026) 2021R1C1C1008713