• Bulletin of the Korean Mathematical Society
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• v.49 no.3
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• pp.481-493
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• 2012

Let $S$ be a upper triangular operator such that $M^L_S:\mathcal{U}_2{\rightarrow}\mathcal{U}_2$ defined by $M^L_S(F)=SF$ is a contraction. Then there exists an unitary linear system whose state space is the extension space $\tilde{D}_L$(S) associated with $\mathcal{H}_L$(S).

• Journal of the Korean Data and Information Science Society
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• v.22 no.3
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• pp.613-618
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• 2011

The proposed method is based on a penalized log partial likelihood of Cox proportional hazard model with L1-penalty. We use the iteratively reweighted least squares procedure to solve L1 penalized log partial likelihood function of Cox proportional hazard model. It provide the ecient computation including variable selection and leads to the generalized cross validation function for the model selection. Experimental results are then presented to indicate the performance of the proposed procedure.

• Journal of the Korean Mathematical Society
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• v.47 no.1
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• pp.29-40
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• 2010

In this paper, we study a generalization of the Banach space B($l_2$) of all bounded linear operators on $l_2$. Over this space, we present some reasonable ways to define Schatten-type classes which are generalizations of the classical Schatten classes of compact operators on $l_2$.

• Bulletin of the Korean Mathematical Society
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• v.51 no.1
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• pp.237-252
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• 2014

In this paper, we give a necessary and sufficient condition for the hyponormality of the block Toeplitz operators $T_{\Phi}$, where ${\Phi}$ = $F+G^*$, F(z), G(z) are some matrix valued polynomials on the vector valued Bergman space $L^2_a(\mathbb{D},\mathbb{C}^n)$. We also show some necessary conditions for the hyponormality of $T_{F+G^*}$ with $F+G^*{\in}h^{\infty}{\otimes}M_{n{\times}n}$ on $L^2_a(\mathbb{D},\mathbb{C}^n)$.

• East Asian mathematical journal
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• v.15 no.1
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• pp.91-103
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• 1999

• Bulletin of the Korean Mathematical Society
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• v.32 no.2
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• pp.205-209
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• 1995

Throughout this paper X is a Banach space and $\mu$ is the Lebesgue measure on [0, 1] and all operators are assumed to be bounded and linear. $L^1(\mu)$ is the Banach space of all (classes of) Lebesgue integrable functions on [0, 1] with its usual norm. Let $T : L^1(\mu) \to X$ be an operator.

• Kyungpook Mathematical Journal
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• v.46 no.1
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• pp.31-48
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• 2006

In this paper, we prove a weighted norm inequality for the Marcinkiewicz integral operator $\mathcal{M}_{{\Omega},h}$ when $h$ satisfies a mild regularity condition and ${\Omega}$ belongs to $L(log L)^{1l2}(S^{n-1})$, $n{\geq}2$. We also prove the weighted $L^p$ boundedness for a class of Marcinkiewicz integral operators $\mathcal{M}^*_{{\Omega},h,{\lambda}}$ and $\mathcal{M}_{{\Omega},h,S}$ related to the Littlewood-Paley $g^*_{\lambda}$-function and the area integral S, respectively.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2016.05a
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• pp.15-17
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• 2016

The congestion situation of Korea's port is further inclining due to the number of arriving and departing vessels and increase in the size of the size. Indicators for assessing whether the Vessel Traffic Congestion is called the Marine Traffic Congestion and it is used as a diagnostic entries in the Maritime Traffic Safety Audit System. In the diagnostic system, 6L (longitudinal) X 3.2L (transverse) is used as ship's domain in cases of harbor. This study is to determine the safety distance of the VTS officer and the ship operators by targeting the Busan harbor, which has the most number of ships that arrive/depart in Korea and listen to the communication of the VTS and calculate the communication time of the VTS officer and the ship operators for 7 days. By utilizing the distance communication port, the safety distance between the controllers and the ship operators is derived. It can be used for basic information of VTS Officer and Ship's operator's Safety distance in Busan port's in&out harbor.

• Journal of the Korean Mathematical Society
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• v.54 no.3
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• pp.713-732
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• 2017

Let ${\Omega}{\in}L^s(S^{n-1})$ for s > 1 be a homogeneous function of degree zero and b be BMO functions or Lipschitz functions. In this paper, we obtain some boundedness of the $Calder{\acute{o}}n$-Zygmund singular integral operator $T_{\Omega}$ and its commutator [b, $T_{\Omega}$] on Herz-type Hardy spaces with variable exponent.

• Bulletin of the Korean Mathematical Society
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• v.33 no.3
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• pp.445-453
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• 1996

A closed subspace J of a Banach space X is called an M-ideal in X if the annihilator $J^\perp$ of J is an L-summand of $X^*$. That is, there exists a closed subspace J' of $X^*$ such that $X^* = J^\perp \oplus J'$ and $\left\$\mid$ p + q \right\$\mid$ = \left\$\mid$ p \right\$\mid$ + \left\$\mid$ q \right\$\mid$$ wherever $p \in J^\perp and q \in J'$.