• 대한수학회보
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• 제54권3호
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• pp.875-894
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• 2017

Let $[n]=\{1,2,{\ldots},n\}$. A set ${\mathbf{A}}=\{A_1,A_2,{\ldots},A_l\}$ is a minimal cover of [n] if ${\cup}_{1{\leq}i{\leq}l}A_i=[n]$ and $$\bigcup_{{1{\leq}i{\leq}l,}\\{i{\neq}j_0}}A_i{\neq}[n]\text{ for all }j_0{\in}[l]$$. Let ${\mathcal{C}}(n)$ denote the collection of all minimal covers of [n], and write $C_n={\mid}{\mathcal{C}}(n){\mid}$. Let ${\mathbf{A}}{\in}{\mathcal{C}}(n)$. An element $u{\in}[n]$ is critical in ${\mathbf{A}}$ if it appears exactly once in ${\mathbf{A}}$. Two minimal covers ${\mathbf{A}},{\mathbf{B}}{\in}{\mathcal{C}}(n)$ are said to be restricted t-intersecting if they share at least t sets each containing an element which is critical in both ${\mathbf{A}}$ and ${\mathbf{B}}$. A family ${\mathcal{A}}{\subseteq}{\mathcal{C}}(n)$ is said to be restricted t-intersecting if every pair of distinct elements in ${\mathcal{A}}$ are restricted t-intersecting. In this paper, we prove that there exists a constant $n_0=n_0(t)$ depending on t, such that for all $n{\geq}n_0$, if ${\mathcal{A}}{\subseteq}{\mathcal{C}}(n)$ is restricted t-intersecting, then ${\mid}{\mathcal{A}}{\mid}{\leq}{\mathcal{C}}_{n-t}$. Moreover, the bound is attained if and only if ${\mathcal{A}}$ is isomorphic to the family ${\mathcal{D}}_0(t)$ consisting of all minimal covers which contain the singleton parts $\{1\},{\ldots},\{t\}$. A similar result also holds for restricted r-cross intersecting families of minimal covers.

• Kyungpook Mathematical Journal
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• 제45권1호
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• pp.137-152
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• 2005

We introduce the concept of what we call "regular difference covers" and prove many nonexistence results and provide some new constructions. Although the techniques employed mirror those used to investigate difference sets, the end results in this new setting are quite different.

• 한국정보과학회논문지:시스템및이론
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• 제36권1호
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• pp.40-51
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• 2009

그래프 G의 쌍형 다대다 k-서로소인 경로 커버(쌍형 k-DPC)는 k개의 서로 다른 소스-싱크 쌍을 연결하며 그래프에 있는 모든 정점을 지나는 k개의 서로소인 경로 집합이다. 이 논문에서는 재귀원형군 G($cd^m$,d), $d{\geq}3$과 토러스에서 서로소인 경로 커버를 고려하여, 이분 그래프가 아니고 분지수가 $\delta$인 재귀원형군과 토러스는 고장 요소(정점이나 에지)가 f개 이하일 때 $f+2k{\leq}{\delta}-1$을 만족하는 임의의 f, $k{\geq}1$에 대하여 쌍형 k-DPC를 가짐을 보인다.

• 대한수학회보
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• 제55권2호
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• pp.611-624
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• 2018

In this paper, we study Weierstrass semigroups of ramification points on double covers of plane curves of degree 6. We determine all the Weierstrass semigroups when the genus of the covering curve is greater than 29 and the ramification point is on a total flex.

• 대한수학회논문집
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• 제20권2호
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• pp.209-219
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• 2005

Tor-torsion theory was defined by Jan Trlifaj in 2000. In this paper we introduce the notion of Co envelopes, CoCovers and Tor-generators as dual of envelopes, covers and generators in cotorsion(Ext-torsion) theory and deduce that each R-module has a projective and a cotorsion coprecover.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제20권2호
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• pp.103-108
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• 2013

Observing that for any space X, there is a Wallman sublattice $\mathfrak{A}_X$ and that QFX is homeomorphic to a subspace $X_q$ of the Wallman cover $\mathfrak{L}(\mathfrak{A}_X)$ of $\mathfrak{A}_X$, we show that ${\beta}QFX$ and $\mathfrak{L}(\mathfrak{A}_X)$ are homeomorphic.

• 설비공학논문집
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• 제19권11호
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• pp.797-802
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• 2007

The effects of window cover on the performance of the plate type radiant cooling test system are studied. The cover materials tested are 2mm, 1mm, 0.7mm glass, Cokin 007 filter, and PVC film. The measurements are performed during the September nights of 2005 at the rooftop of the building in Seoul. The equivalent height of the building is about a building with twelve floors. The radiant cooling performance of the black painted and aluminum film coated plate are compared under no cover condition. Also the results are compared when the system has cover over the plate. In general, the covers reduce the radiant cooling temperature differences during the nighttime. Among these covers, the PVC film cover shows the best performance. In some cases, the plate with PVC film cover shows lower temperatures than the system without cover.

• Journal of information and communication convergence engineering
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• 제9권4호
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• pp.363-368
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• 2011

The DGPS transmits the enhancement signal to GPS using the medium frequency band. The NDGPS service that covers the Korean peninsula has been started since 2009. The service area of ocean-based DGPS(maritime-DGPS) reference stations covers the 100NM, but land-based DGPS(land-DGPS) covers 80km service area less than that of maritime DGPS. The DGPS's antenna has the top-loaded monopole antenna type. Top-loaded monopoles are the logical antennas to be used in order to get a low profile antenna and a performance according to the broadcaster and communication needs. The antenna needs to get the ground plane with good conductivity characteristics and flat ground plane without obstacle near to the transmitting antenna. In this paper, the radiation characteristics of an equivalent MF antenna are analyzed in view points of the ground conductivity and the ground plane with obstacle near to the antenna.

• 생물환경조절학회지
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• 제21권3호
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• pp.286-293
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• 2012

전남지역 13곳의 유기과원에서 자생하는 다년생 초종을 조사하여 과수 생장을 위한 양분 공급원으로의 적합한 초생식물을 탐색하기 위하여 수행되었다. 과원에 발생한 초종은 4월과 6월 그리고 8월에 조사하였다. 4월과 6월에 각각 발생한 개밀과 큰개기장에서 가장 높은 건물중을 보였고, 이는 질소와 인산 칼리 고정량을 크게 증가시켰다. 8월에는 다년생초생 발생량이 4월과 6월에 비교하여 감소하였다. 예초된 개밀과 큰개기장의 초생 잔사량은 20년생의 과일나무가 생장하기 위해 필요한 연간 평균 질소(20kg/10a), 인산(11kg/10a), 그리고 칼리(19kg/10a) 수준을 충족시킨 것으로 관찰되었다.

• 한국측량학회지
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• 제32권6호
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• pp.607-615
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• 2014

RVI (Radar Vegetation Index) has shown some promise in the vegetation fields, but its relationship with MVI (Multispectral Vegetation Index) is not known in the context of various land covers. Presented herein is a comparative analysis of the MVI values derived from the LANDSAT-8 and RVI values originating from the RADARSAT-2 quad-polarimetric SAR (Synthetic Aperture Radar) data. Among the various multispectral vegetation indices, NDVI (Normalized Difference Vegetation Index) and SAVI (Soil Adjusted Vegetation Index) were used for comparison with RVI. Four land covers (urban, forest, water, and paddy field) were compared, and the patterns were investigated. The experiment results demonstrated that the RVI patterns of the four land covers are very similar to those of NDVI and SAVI. Thus, during bad weather conditions and at night, the RVI data could serve as an alternative to the MVI data in various application fields.