정민구 교수

We study the relationship between the residuality of the set of norm attaining functionals on a Banach space and the residuality and the denseness of the set of norm attaining operators between Banach spaces. Our first main result says that if C is a bounded subset of a Banach space X which admit an LUR renorming satisfying that, for every Banach space Y, the operators T from X to Y for which the supremum of ‖Tx‖ with x∈C is attained are dense, then the Gδ set of those functionals which strongly

본 연구에서는 아연도금 강판의 탈‧부착이 가능한 데크플레이트와 중공률을 효과적으로 적용한 “콩(bean)”형 중공형성체를 삽입하여 1방향 중공슬래브의 휨 성능을 평가하였다. 1방향 중공슬래브의 휨 성능을 검증하기 위해 2개의 실험체를 제작하여 실험을 수행 하였다. 실험결과 탈부착형 데크와 탈부착형 중공데크 실험체의 휨 강도는 KCI2012 기준에 따른 설계 강도에비해 각각 6.6 %와 15.8 % 높게 나타났으며, 슬래브 중앙에서 초기 균열 발생 이후 양단부로 균열이 확산되는 전형적인 휨파괴 거동을 보였다. 또한 단면2차모멘트를 통해 단면성능에 대한 검증을 실시하였다. 중공률 32.8 %를 가진 탈부착형 중공데크는 KCI2012 구조설계기준에 제시된 1방향 중공슬래브의 휨설계 강도를 상회하는 것으로 나타났다. 이에 따라 슬래브의 중량저감과 데크플레이트의 사용에 의한 시공성 개선, 아연도금 강판의 재사용을 통해 일반 철근콘크리트 슬래브를 대체 될 것으로 기대된다.

Abstract In this paper, we are interested in studying when an element z in the projective tensor product $X {\widehat{\otimes}_\pi} Y$ turns out to be a Daugavet point. We prove first that, under some hypothesis, the assumption of $X {\widehat{\otimes}_\pi} Y$ having the Daugavet property implies the existence of a great amount of isometries from Y into X*. Having this in mind, we provide methods for constructing non-trivial Daugavet points in $X {\widehat{\otimes}_\pi} Y$. We show that C(K)-spa

Abstract In this paper, we consider the Bishop–Phelps–Bollobás point property for various classes of operators on complex Hilbert spaces, which is a stronger property than the Bishop–Phelps–Bollobás property. We also deal with analogous problem by replacing the norm of an operator with its numerical radius.

In this paper, we introduce a concept of norm-attainment in the projective symmetric tensor product of a Banach space X, which turns out to be naturally related to the classical norm-attainment of N -homogeneous polynomials on X. Due to this relation, we can prove that there exist symmetric tensors that do not attain their norms, which allows us to study the problem of when the set of norm-attaining elements in is dense. We show that the set of all normattaining symmetric tensors is dense in for

Abstract Motivated by the result of Dantas et al. in Nonlinear Anal. (2023) that there exist metric spaces for which the set of strongly norm‐attaining Lipschitz functions does not contain an isometric copy of , we introduce and study a weaker notion of norm‐attainment for Lipschitz functions called the pointwise norm‐attainment. As a main result, we show that for every infinite metric space , there exists a metric space such that the set of pointwise norm‐attaining Lipschitz functions on contai

We investigate some approximation properties of Banach spaces which are described in terms of Lipschitz maps. First, we present characterizations of the Lipschitz approximation property, and prove that a Banach space $X$ has the approximation property whe

We show that the duals of Banach algebras of scalar-valued bounded holomorphic functions on the open unit ball $B_E$ of a Banach space $E$ lack weak$^*$-strongly exposed points. Consequently, we obtain that some Banach algebras of holomorphic functions on an arbitrary Banach space have the Daugavet property which extends the observation of P. Wojtaszczyk. Moreover, we present a new denseness result by proving that the set of norm-attaining vector-valued holomorphic functions on the open unit bal