• 호남수학학술지
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• 제37권1호
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• pp.135-147
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• 2015

Owing to the notion of a normal adjacency for a digital product in [8], the study of product properties of digital topological properties has been substantially done. To explain a normal adjacency of a digital product more efficiently, the recent paper [22] proposed an S-compatible adjacency of a digital product. Using an S-compatible adjacency of a digital product, we also study product properties of digital topological properties, which improves the presentations of a normal adjacency of a digital product in [8]. Besides, the paper [16] studied the product property of two digital covering maps in terms of the $L_S$- and the $L_C$-property of a digital product which plays an important role in studying digital covering and digital homotopy theory. Further, by using HS- and HC-properties of digital products, the paper [18] studied multiplicative properties of a digital fundamental group. The present paper compares among several kinds of adjacency relations for digital products and proposes their own merits and further, deals with the problem: consider a Cartesian product of two simple closed $k_i$-curves with $l_i$ elements in $Z^{n_i}$, $i{\in}\{1,2\}$ denoted by $SC^{n_1,l_1}_{k_1}{\times}SC^{n_2,l_2}_{k_2}$. Since a normal adjacency for this product and the $L_C$-property are different from each other, the present paper address the problem: for the digital product does it have both a normal k-adjacency of $Z^{n_1+n_2}$ and another adjacency satisfying the $L_C$-property? This research plays an important role in studying product properties of digital topological properties.

• 한국화재소방학회논문지
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• 제25권5호
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• pp.8-13
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• 2011

고강도 콘크리트는 화재 시 고온에 노출되어 폭렬현상이 발생된다. 폭렬은 철근노출과 함께 구조부재의 단면을 감소시키며, 이로 인하여 구조적 거동에 심각한 문제를 발생시킨다. 본 연구의 목적은 이러한 고강도 콘크리트의 내화피복재로 활용하기 것으로 퍼라이트와 폴리프로필렌 섬유로 경량모르타르를 제조하여 그 역학적 성상을 파악하는데 있다. 이에 따른 실험인자로는 물시멘트비, 골재시멘트비, 폴리프로필렌 섬유 첨가량이다. 연구결과 퍼라이트와 폴리프로필렌 섬유를 첨가함으로서 모르타르의 공극구조를 변화시킬 수 있었으며, 단위중량을 감소시킬 수 있었다. 또한, 고강도 콘크리트의 내화피복재로서 경량모르타르를 사용할 수 있는 가능성을 확인하였다.

• Structural Engineering and Mechanics
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• 제54권5호
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• pp.955-971
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• 2015

In this paper, the influence of the polled direction of piezoelectric materials on the stress distribution is studied under time-harmonic dynamical load (time-harmonic Lamb's problem). The system considered in this study consists of piezoelectric covering layer and piezoelectric half-plane, and the harmonic dynamical load acts on the free face of the covering layer. The investigations are carried out by utilizing the exact equations of motion and relations of the linear theory of electro-elasticity. The plane-strain state is considered. It is assumed that the perfect contact conditions between the covering layer and half-plane are satisfied. The boundary value problems under consideration are solved by employing Fourier exponential transformation techniques with respect to coordinates directed along the interface line. Numerical results on the influence of the polled direction of the piezoelectric materials such as PZT-5A, PZT-5H, PZT-4 and PZT-7A on the normal stresses, shear stresses and electric potential acting on the interface plane are presented and discussed. As a result of the analyses, it is established that the polled directions of the piezoelectric materials play an important role on the values of the studied stresses and electric potential.

• 한국컴퓨터정보학회논문지
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• 제11권1호
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• pp.11-18
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• 2006

LAD(Logical Analysis of Data)는 Boolean-logic에 기반을 둔 데이터 마이닝 방법론이다. LAD에 의한 데이터 분석 시 중요한 과정은 데이터 집합에 숨겨진 구조적 정보를 패턴의 형식으로 발견해내는 패턴 생성 단계이다. 기존의 패턴 생성 방법은 열거법에 기반을 두고 있어 높은 차수의 패턴을 생성하는 것은 실질적으로 불가능하였다. 본 논문에서는 최적화에 기반을 둔 패턴 생성 방법론을 제안하고 혼합 정수 선형 모형과 SCP(Set Covering Problem)의 두 가지 모형을 제안한다. 기계학습 분야에서 널리 쓰이는 데이터 집합에 대해 제안된 패턴 생성 방법을 이용한 분석 실험을 통하여 기존의 패턴 생성 방법으로는 생성될 수 없는 패턴을 쉽게 생성하는 효율성을 입증하였다.

• 정보처리학회논문지A
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• 제16A권1호
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• pp.35-42
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• 2009

이 논문은 지능형 로봇을 위한 새로운 커버리지 알고리즘을 제안한다. 커버리지 알고리즘의 성능을 향상하기 위한 많은 연구들은 전체 커버리지 완료 시간을 최소화하는데 초점을 맞추어왔다. 그러나, 만일 전체 커버리지를 완료하기에 충분한 시간이 없다면, 최적의 경로는 달라질 수 있다. 이러한 문제를 해결하기 위하여 본 논문에서는 MaxCoverage라고 하는 데드라인이 있을 경우에 가능한 많은 면적을 커버하기 위한 새로운 커버리지 알고리즘을 제안한다. MaxCoverage 알고리즘은 이동 경로를 셋 커버 문제를 위한 그리디 알고리즘을 이용하여 결정한다. 실험 결과에 의하면 MaxCoverage 알고리즘은 임의의 데드라인에 대하여 다른 알고리즘들에 비해 향상된 성능을 보여준다.

• 대한산업공학회지
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• 제24권4호
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• pp.571-578
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• 1998

In this paper, we deal with a node weighted Steiner Ring Problem (SRP) arising from the deployment of Synchronous Optical Networks (SONET), a standard of transmission using optical fiber technology. The problem is to find a minimum weight cycle (ring) covering a subset of nodes in the network considering node and link weights. We have developed two mathematical models, one of which is stronger than the other in terms of LP bounds, whereas the number of constraints of the weaker one is polynomially bounded. In order to solve the problem optimally, we have developed some preprocessing rules and valid inequalities. We have also prescribed an effective heuristic procedure for providing tight upper bounds. Computational results show that the stronger model is better in terms of computation time, and valid inequalities and preprocessing rules are effective for solving the problem optimally.

• Journal of Electrical Engineering and Technology
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• 제7권2호
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• pp.151-156
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• 2012

The current study presents a zero-one integer programming approach to determine the minimum break point set for the coordination of directional relays. First, the network is reduced if there are any parallel lines or three-end nodes. Second, all the directed loops are enumerated to reduce the iteration. Finally, the problem is formulated as a set-covering problem, and the break point set is determined using the zero-one integer programming technique. Arbitrary starting relay locations and the arbitrary consideration of relay sequence to set and coordinate relays result in navigating the loops many times and futile attempts to achieve system-wide relay coordination. These algorithms are compared with the existing methods, and the results are presented. The problem is formulated as a setcovering problem solved by the zero-one integer programming approach using LINGO 12, an optimization modeling software.

• 대한산업공학회지
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• 제41권4호
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• pp.396-407
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• 2015

The literature about intelligence assets allocation focused on mainly single or partial assets such as TOD and GSR. Thus, it is limited in application to the actual environment of operating various assets. In addition, field units have generally vulnerabilities because of depending on qualitative analysis. Therefore, we need a methodology to ensure the validity and reliability of intelligence asset allocation. In this study, detection probability was generated using digital geospatial data in MGIS (Military Geographic Information System) and simulation logic of BCTP (Battle Commander Training Programs) in the R.O.K army. Then, the optimal allocation mathematical model applied concept of simultaneous integrated management, which was developed based on the partial set covering model. Also, the proposed GA (Genetic Algorithm) provided superior results compared to the mathematical model. Consequently, this study will support effectively decision making by the commander by offering the best alternatives for optimal allocation within a reasonable time.

• 대한전자공학회:학술대회논문집
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• 대한전자공학회 2003년도 컴퓨터소사이어티 추계학술대회논문집
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• pp.11-14
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• 2003

In interconnection network for parallel processing, the cycle partitioning problem for parallel transmission with faulty vertieces or edges is very important. In this paper, we assume that k($\leq$m-1) edges do not share any vertices of m dimension hypercube Q$_{m}$ and show that it is possible to construct a cycle set which consists of k cycles covering all the vertices of the hypercube and one cycle including one of the given edges. This cycle set can be used to parallel transmission between two vertices joined by faulty edges.s.

• 한국화재소방학회논문지
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• 제24권4호
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• pp.41-46
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• 2010

고강도 콘크리트는 대형 사회기반 구조물로서 많이 활용되고 있다. 고강도 콘크리트는 우수한 재료적 성능과 내구성을 확보하고 있지만 반면에 화재에 대한 급작스러운 폭렬현상으로 인하여 구조적인 문제를 야기시키기도 한다. 따라서 본 연구에서는 콘크리트 피복두께에 추가하여 내화피복재를 사용함으로써 내화피복두께에 따른 콘크리트의 내화성능을 평가하고 최적의 내화피복두께를 산정하는 실험적 연구를 수행하였다. 내화피복재를 10mm 간격으로 증가시키면서 실험을 수행한 결과 콘크리트의 내화성능이 크게 향상됨을 볼 수 있었으며, 최적의 내화피복두께는 약 1~3mm로 산정되었다. 또한 폭렬에 의하여 급작스러운 콘크리트 내부의 온도상승 이후 기화열에 의한 열손실로 완만하게 온도가 상승되는 현상이 실험적으로 관측되었다. PP 섬유는 약 $200^{\circ}C$ 부근에서 용해되어 고온에서는 빈 채널만 남게 되므로 내부 증기압을 저감시켜주는 역할도 관측되었다.