• Journal of applied mathematics & informatics
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• 제39권1_2호
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• pp.155-163
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• 2021

For a connected graph G of order n, a set S of vertices is called a double geodetic set of G if for each pair of vertices x, y in G there exist vertices u, v ∈ S such that x, y ∈ I[u, v]. The double geodetic number dg(G) is the minimum cardinality of a double geodetic set. Any double godetic set of cardinality dg(G) is called a dg-set of G. A connected double geodetic set of G is a double geodetic set S such that the subgraph G[S] induced by S is connected. The minimum cardinality of a connected double geodetic set of G is the connected double geodetic number of G and is denoted by dgc(G). A connected double geodetic set of cardinality dgc(G) is called a dgc-set of G. Connected graphs of order n with connected double geodetic number 2 or n are characterized. For integers n, a and b with 2 ≤ a < b ≤ n, there exists a connected graph G of order n such that dg(G) = a and dgc(G) = b. It is shown that for positive integers r, d and k ≥ 5 with r < d ≤ 2r and k - d - 3 ≥ 0, there exists a connected graph G of radius r, diameter d and connected double geodetic number k.

• Journal of applied mathematics & informatics
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• 제30권5_6호
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• pp.871-882
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• 2012

For a connected graph G of order $n$, an ordered set $S=\{u_1,u_2,{\cdots},u_k\}$ of vertices in G is a linear edge geodetic set of G if for each edge $e=xy$ in G, there exists an index $i$, $1{\leq}i$ < $k$ such that e lie on a $u_i-u_{i+1}$ geodesic in G, and a linear edge geodetic set of minimum cardinality is the linear edge geodetic number $leg(G)$ of G. A graph G is called a linear edge geodetic graph if it has a linear edge geodetic set. The linear edge geodetic numbers of certain standard graphs are obtained. Let $g_l(G)$ and $eg(G)$ denote the linear geodetic number and the edge geodetic number, respectively of a graph G. For positive integers $r$, $d$ and $k{\geq}2$ with $r$ < $d{\leq}2r$, there exists a connected linear edge geodetic graph with rad $G=r$, diam $G=d$, and $g_l(G)=leg(G)=k$. It is shown that for each pair $a$, $b$ of integers with $3{\leq}a{\leq}b$, there is a connected linear edge geodetic graph G with $eg(G)=a$ and $leg(G)=b$.

• Journal of applied mathematics & informatics
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• 제16권1_2호
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• pp.525-532
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• 2004

For two vertices u and v of an oriented graph D, the set I(u, v) consists of all vertices lying on a u-v geodesic or v-u geodesic in D. If S is a set of vertices of D, then I(S) is the union of all sets 1(u, v) for vertices u and v in S. The geodetic number g(D) is the minimum cardinality among the subsets S of V(D) with I(S) = V(D). In this paper, we give a partial answer for the conjecture by G. Chartrand and P. Zhang and present some results on orient able geodetic number.

• Journal of applied mathematics & informatics
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• 제32권1_2호
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• pp.255-266
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• 2014

For a connected graph G = (V,E) of order at least two, a set S of vertices of G is a monophonic set of G if each vertex v of G lies on an x - y monophonic path for some elements x and y in S. The minimum cardinality of a monophonic set of G is the monophonic number of G, denoted by m(G). Certain general properties satisfied by the monophonic sets are studied. Graphs G of order p with m(G) = 2 or p or p - 1 are characterized. For every pair a, b of positive integers with $2{\leq}a{\leq}b$, there is a connected graph G with m(G) = a and g(G) = b, where g(G) is the geodetic number of G. Also we study how the monophonic number of a graph is affected when pendant edges are added to the graph.

• 한국측량학회지
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• 제13권1호
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• pp.1-12
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• 1995

본 연구에서는 국립지리원에서 20여년간(1975-1994) 관측한 정밀 1차 측지망 자료를 연도(작업구역)별, 블록별로 조정하여 전산처리에 필요한 데이타 Set로 구축하고, 전국 동시망 조정을 실시하여 우리 나라 측지망의 정확도 평가 및 오차전파 상태, 국토의 수평지각변동을 파악하였다. 이를 토대로 우리 나라 최초의 동질성 있는 정밀 1차 기준점(1, 2등 삼각점)의 실용성과 (기준점 좌표 94)를 산정 제시하였다.

• Structural Engineering and Mechanics
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• 제27권3호
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• pp.293-310
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• 2007

Theoretical foundation for the buckling load determination in reinforced concrete columns is described and analytical solutions for buckling loads of the Euler-type straight reinforced concrete columns given. The buckling analysis of the limited set of restrained reinforced concrete columns is also included, and some conclusions regarding effects of material non-linearity and restrain stiffnesses on the buckling loads and the buckling lengths are presented. It is shown that the material non-linearity has a substantial effect on the buckling load of the restrained reinforced concrete columns. By contrast, the steel/concrete area ratio and the layout of reinforcing bars are less important. The influence on the effective buckling length is small.

• 한국측량학회지
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• 제39권5호
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• pp.313-319
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• 2021

The national geodetic reference frame of Korea was adopted in 2003, which is referenced to ITRF (International Terrestrial Reference Frame) 2000 at the epoch of January 1, 2002. For precise positioning based on the satellites, it should be thoroughly maintained to the newest global reference frame. Other than plate tectonic motion, there are significant events or changes such as earthquakes, antenna replacement, PSD (Post-Seismic Deformation), seasonal variation etc. We processed three years of GNSS (Global Navigation Satellite System) data(60 NGII CORS stations, 51 IGS core stations) to produce daily solutions minimally constrained to ITRF. From the time series of daily solutions, the sites with unexpected discontinuity were identified to set up an event(mostly antenna replacement). The combined solution with minimum constraints was estimated along with the velocity, the offsets, and the periodic signals. The residuals show that the surrounding environment also affects the time series to a certain degree, thus it should be improved eventually. The transformation parameters to ITRF2014 were calculated with stability and consistency, which means the national geodetic reference frame is properly aligned to the global reference frame.

• 한국측량학회지
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• 제38권6호
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• pp.717-723
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• 2020

VLBI, SLR, DORIS, GNSS와 같은 우주측지기술 사이의 3차원 벡터를 결정하는 작업은 ITRF에 중요한 요소이다. 따라서 각각의 우주측지기술에 해당되는 IVP를 정확하게 계산할 필요가 있다. 본 연구에서는 기존 모델에 비해 업데이트된 수학모델을 사용하여 세종시에 위치한 VLBI의 IVP 위치를 계산함으로써 계산의 효율과 신뢰성을 높였다. 관측값으로는 안테나에 부착된 반사타겟의 좌표가 사용되었으며 이때 관측오차크기는 1.5 mm로 설정하였다. 조정계산을 통해 VLBI IVP 좌표와 정확도를 계산했으며 기존 연구에서 제시한 값과 비교했을 때 성공적으로 계산이 된 것으로 판단된다. 하지만 실제 관측오차가 고려된 VLBI IVP를 계산하기 위해서는 향후 VLBI IVP 계산을 위한 추가적인 지상측량이 필요하다.

• Computers and Concrete
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• 제14권4호
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• pp.463-477
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• 2014

The modelling approach in the case of connections in precast buildings is specific. The assembly of the constitutive parts of the connection requires the inclusion of contact definitions in the model. In addition, the material non-linearity including the influence of the spatial stress distribution should be taken into account where appropriate. Here a complex model of a beam-to-column dowel connection is presented. Experiments on the analysed connection were performed within the framework of the European project SAFECAST (Performance of Innovative Mechanical Connections in Precast Building Structures under Seismic Conditions). Several material and interaction parameters were investigated and the influence of each of them was evaluated. The set of parameters which gave the best match with the experiments was chosen.

• 한국측량학회지
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• 제12권1호
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• pp.15-24
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• 1994

우리 나라의 독자적인 원점체계에 의한 정밀 측지망성과의 확립을 위하여 1975년에 착수된 정밀 1차 측지망 사업은 1993년에 제1회 관측이 완료되었으며 1994년에는 일부지역에 대한 보충관측이 진행되고 있다. 본 연구에서는 측지망 측량성과의 정확도 및 측지망 강도를 평가하고자 작업구역별, 블럭별 조정계산을 실시하였다. 조정 및 분석결과, 작업규정 전반에 대한 수정, 보완을 위한 체계적인 연구가 필요하며, 정밀측지망의 실용성과 산정에 필수적인 기초자료가 확보되었다.