• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.15 no.3
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• pp.34-44
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• 2016

This study was initiated to evaluate the performance of methodologies to estimate the space mean speed(SMS) using the time mean speed(TMS) which was collected from the vehicle detection system(VDS) in expressways. To this end, the methodologies presented in prior studies were firstly summarized. It is very hard to achieve exact SMSs and TMSs due to mechanical and communication errors in the field. Thus, a microscopic traffic simulation model was utilized to evaluated the performance. As a result, the harmonic mean and volume-distance weighted harmonic mean were close to the SMS in the case in which the TMSs of individual vehicles were used. However, when the 30-second-interval aggregated TMS were used, the volume-distance weighted harmonic mean was outstanding. In this study, a radar detector was installed in the Joongbu expressway to collect the SMS. The trajectory of individual vehicles collected from the detector were used to calculate the SMS, which was compared with the estimates using other methodologies selected in this study. As a result, the volume-distance weighted mean was turned out to be close to the SMS. However, as the congestion becomes severe. the deviation between the two speed becomes bigger.

• Journal of the Korean Institute of Landscape Architecture
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• v.47 no.6
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• pp.103-114
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• 2019

Despite recent projects to create urban forests to reduce the levels of particulate matter, objective evaluation criteria for selecting suitable sites for the projects have not been provided. The purposes of this study are to identify assessment items for the evaluation of available spaces for urban forests for the reduction of particulate matter and to analyze the relative importance of the items using the Analytic Hierarchy Process (AHP). We identified a total of 19 items in five categories through a literature review and a panel discussion. A total of 29 responses were collected from surveys given to experts, and an AHP analysis was conducted on the results. As a result, 'locational characteristics' (0.355) received the highest weighted value among the five categories, followed by 'planting type of existing green space' (0.184), 'weather conditions' (0.183), 'physical characteristics' (0.15), and 'human social environment' (0.128). In addition, among all the assessment items, 'proximity of source apportionment of particulate matter' (0.143) had higher weighted value while 'plantation of existing green space' (0.024) had the lowest weighted value. This study will present objective criteria and directions in the selecting of available spaces to create urban forests for the reduction of particulate matter.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.41.1-41.1
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• 2013

To test whether the close relationships between host and satellite galaxies in isolated groups are also found in the harsh environment of a galaxy cluster, we carry out a case study of WHL 085910.0+294957, a galaxy cluster at z=0.30, using deep images obtained with the 2.1-m Otto Struve telescope and CQUEAN CCD camera. When environmental parameters are controlled, the local weighted mean color of faint galaxies shows a measurable correlation with the color of their bright ($M_i$ < -18) neighbor. The most striking result is that the red (r - i > 0.2) and bright galaxies within 200 kpc distance from the center of the cluster are correlated in color with very faint ($M_i$ > -14) galaxies around them by $(r-i)_{satellites}=(7.276{\pm}1.402){\times}(r-i)_{host}-2.434$ (correlation coefficient = 0.665). We suggest three scenarios to interpret the results: vestiges of infallen groups, dwarf capturing, and tidal tearing of bright galaxies.

• Bulletin of the Korean Mathematical Society
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• v.52 no.1
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• pp.85-103
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• 2015

We prove some sharp extremal distance results for functions in various spaces of analytic functions on bounded strictly pseudoconvex domains with smooth boundary. Also, we obtain atomic decompositions in multifunctional Bloch and weighted Bergman spaces of analytic functions on strictly pseudoconvex domains with smooth boundary, which extend known results in the classical case of a single function.

• Bulletin of the Korean Mathematical Society
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• v.55 no.4
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• pp.1263-1271
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• 2018

We introduce new generalized inverses (named the WgDMP inverse and dual WgDMP inverse) for a bounded linear operator between two Hilbert spaces, using its Wg-Drazin inverse and its Moore-Penrose inverse. Some new properties of WgDMP inverse and dual WgDMP inverse are obtained and some known results are generalized.

• Communications of the Korean Mathematical Society
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• v.27 no.3
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• pp.537-545
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• 2012

In the present paper, we show that a continuous linear operator T on a Frechet space satisfies the Hypercyclic Criterion with respect to a syndetic sequence must satisfy the Kitai Criterion. On the other hand, an operator, hereditarily hypercyclic with respect to a syndetic sequence must be mixing. We also construct weighted shift operators satisfying the Hypercyclicity Criterion which do not satisfy the Kitai Criterion. In other words, hereditarily hypercyclic operators without being mixing.

• Bulletin of the Korean Mathematical Society
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• v.54 no.4
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• pp.1337-1346
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• 2017

We define Bloch-type spaces of ${\mathcal{C}}^1({\mathbb{H}})$ on the upper half plane H and characterize them in terms of weighted Lipschitz functions. We also discuss the boundedness of a composition operator ${\mathcal{C}}_{\phi}$ acting between two Bloch spaces. These obtained results generalize the corresponding known ones to the setting of upper half plane.

• Journal of applied mathematics & informatics
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• v.33 no.3_4
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• pp.327-342
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• 2015

By employing a fixed point theorem in a weighted Banach space, we establish the existence of a solution for a system of impulsive singular fractional differential equations. Some examples are presented to illustrate the efficiency of the results obtained.

• Journal of the Korean Mathematical Society
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• v.51 no.6
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• pp.1209-1220
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• 2014

We prove global gradient estimates in weighted Orlicz spaces for weak solutions of nonlinear elliptic equations in divergence form over a bounded non-smooth domain as a generalization of Calder$\acute{o}$n-Zygmund theory. For each point and each small scale, the main assumptions are that nonlinearity is assumed to have a uniformly small mean oscillation and that the boundary of the domain is sufficiently flat.

• Journal of the Korean Mathematical Society
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• v.45 no.1
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• pp.205-219
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• 2008

It is shown that if $A{\geq}0$ and T are two bounded linear operators on a complex Hilbert space H satisfying the inequality $T^*\;AT{\leq}A$ and the condition $AT=A^{1/2}TA^{1/2}$, then there exists the maximum reducing subspace for A and $A^{1/2}T$ on which the equality $T^*\;AT=A$ is satisfied. We concretely express this subspace in two ways, and as applications, we derive certain decompositions for quasinormal contractions. Also, some facts concerning the quasi-isometries are obtained.