• 대한수학회지
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• 제52권6호
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• pp.1271-1286
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• 2015

An operator T on a complex Hilbert space H is called skew symmetric if T can be represented as a skew symmetric matrix relative to some orthonormal basis for H. In this paper, we study skew symmetric operators with eigenvalues. First, we provide an upper-triangular operator matrix representation for skew symmetric operators with nonzero eigenvalues. On the other hand, we give a description of certain skew symmetric triangular operators, which is based on the geometric relationship between eigenvectors.

• 대한수학회보
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• 제44권4호
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• pp.777-788
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• 2007

An endomorphism ${\alpha}$ of a ring R is called right(left) symmetric if whenever abc=0 for a, b, c ${\in}$ R, $ac{\alpha}(b)=0({\alpha}(b)ac=0)$. A ring R is called right(left) ${\alpha}-symmetric$ if there exists a right(left) symmetric endomorphism ${\alpha}$ of R. The notion of an ${\alpha}-symmetric$ ring is a generalization of ${\alpha}-rigid$ rings as well as an extension of symmetric rings. We study characterizations of ${\alpha}-symmetric$ rings and their related properties including extensions. The relationship between ${\alpha}-symmetric$ rings and(extended) Armendariz rings is also investigated, consequently several known results relating to ${\alpha}-rigid$ and symmetric rings can be obtained as corollaries of our results.

• 통상정보연구
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• 제18권4호
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• pp.333-358
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• 2016

본 연구는 교육서비스 프랜차이즈 제휴 운영에 있어 효과적인 자원배분을 위한 전략적 대안을 제시하고자 프랜차이즈 본사와 가맹원간 관계특성이 관계품질과 제휴의 관계적 성과에 미치는 프로세스를 제안하였다. 모델의 검증을 위해 교육업에 종사하는 가맹원을 대상으로 설문조사를 실시하였으며, 수거된 설문지 중 200개의 설문지를 분석에 사용하였다. 분석결과, 대칭적관계보다는 비대칭적관계에 의해 관계품질의 수준이 더욱 영향을 받는 것으로 나타났다. 특히 교육서비스의 경우 프랜차이즈 본사와 가맹점간 거래특유투자의 불균형이 관계품질을 저하하는데 가장 큰 영향력을 미치는 것으로 나타났다. 또한 외국계 프랜차이즈와 비교하였을 때 국내 로컬 프랜차이즈는 외국계 프랜차이즈보다 역할과 책임의 불균형이 크고, 가맹점들이 기회주의행동을 할 가능성이 높은 것으로 나타났다.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제9권10호
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• pp.4126-4142
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• 2015

Finger vein recognition is a biometric technology using finger veins to authenticate a person, and due to its high degree of uniqueness, liveness, and safety, it is widely used. The traditional Symmetric Local Graph Structure (SLGS) method only considers the relationship between the image pixels as a dominating set, and uses the relevant theories to tap image features. In order to better extract finger vein features, taking into account location information and direction information between the pixels of the image, this paper presents a novel finger vein feature extraction method, Multi-Orientation Weighted Symmetric Local Graph Structure (MOW-SLGS), which assigns weight to each edge according to the positional relationship between the edge and the target pixel. In addition, we use the Extreme Learning Machine (ELM) classifier to train and classify the vein feature extracted by the MOW-SLGS method. Experiments show that the proposed method has better performance than traditional methods.

• International Journal of Precision Engineering and Manufacturing
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• 제5권4호
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• pp.36-42
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• 2004

The shaft with the circular cross section has symmetric structural combination parts to keep the rotating balance. Hence the crack usually initiates from symmetric combination parts due to the stress concentration of these parts. In this study to estimate the fatigue behavior of symmetric cracks, the fatigue test was performed by using a rotary bending tester and the specimen with symmetric defects in circular cross section. The characteristics of crack initiation and propagation on the symmetric surface cracks in circular cross section were examined. We also observed the internal crack using the oxidation coloring method and investigated the fatigue behavior using the relationship between the surface crack and the internal crack. As a result, the fatigue life of symmetric cracks was reduced by 35% compared to that of a single crack. We examined the characteristics of fatigue behavior of elements with symmetric cracks using internal crack propagation rate and maximum stress intensity factor range that were obtained from an approximation method.

• Structural Engineering and Mechanics
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• 제51권3호
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• pp.361-375
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• 2014

The main aim of this paper is to investigate the relationship between thickness and height of the axially symmetric cylindrical reinforced concrete (RC) walls by the help of a meta-heuristic optimization procedure. The material cost of the wall which includes concrete, reinforcement and formwork, was chosen as objective function of the optimization problem. The wall thickness, compressive strength of concrete and diameter of reinforcement bars were defined as design variables and tank volume, radius and height of the wall, loading condition and unit cost of material were defined as design constants. Numerical analyses of the wall were conducted by using superposition method (SPM) considering ACI 318-Building code requirements for structural concrete. The optimum wall thickness-height relationship was investigated under three main cases related with compressive strength of concrete and density of the stored liquid. According to the results, the proposed method is effective on finding the optimum design with minimum cost.

• 한국정밀공학회지
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• 제19권10호
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• pp.84-91
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• 2002

The shaft with the circular cross section have symmetric structural combination parts to keep the rotating balance. Hence the crack usually emanate from symmetric combination parts due to the stress concentration of these parts. In this study to estimate the fatigue behavior of symmetric cracks, the fatigue test was performed by using rotary bending tester and the specimen with symmetric defects in circular cross section. From the facts the characteristics of crack initiation and propagation on the symmetric surface cracks in circular cross section was examined. Also we observed the internal crack using oxidation coloring and investigated the fatigue behavior using the relationship between surface crack and internal crack. As a result of fatigue lift of symmetric cracks was reduced to 35% compared to single crack’s. We examined the characteristics of fatigue behavior in element with symmetric cracks using internal crack propagation rate and maximum stress intensity factor range obtained from approximation method.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 1999년도 학회창립 10주년 기념 1999년도 가을 학술발표회 논문집
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• pp.717-720
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• 1999

Recently, the fiber composite materials such as carbon fiber, glass fiber, or aramid, have been frequently used in strengthening reinforced concrete structures. The fiber composite materials typically have orthotropic characteristic and the strength changes significantly acording to the direction of fibers and the method of the lamination. In this study, an algorithm to estimate the stress-strain relationship of the composite materials which have different fiber directions and symmetric or non-symmetric lamination has been developed by using Tsai-Hill and Tsai-Wu failure criteria and progressive laminate failure theory. This algorithm has been implemented to several stress-strain models for the laterally confined concrete compression members such as Mander, Hosotani, and Nakatsuka. The evaluated stress-strain behaviors by the different models are discussed.

• 한국인터넷방송통신학회논문지
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• 제21권2호
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• pp.103-109
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• 2021

1893년 불란서 Hadamard가 발표한 직교 Hadamard 행렬에 대해 이문호교수는 1989년에 Center Weight Hadamard로 새롭게 정의하여 발표했고 1998년에는 Jacket 행렬을 발견했다. Jacket 행렬은 Hadamard 행렬을 일반화한 것이다. 본 논문에서는 Symmetric Jacket 행렬을 구해 중요한 속성과 패턴을 분석하고 Jacket 행렬의 행렬식과 Eigenvalue을 얻는 방법을 제시하며 Eigen decomposition를 사용하여 이를 증명했다. 이러한 계산은 신호 처리 및 직교 코드 설계에 유용하다. 행렬의 체계를 분석하기 위해 DFT, DCT, Hadamard, Jacket 행렬로 비교해 본다. Galois Field의 대칭 행렬에서 Jacket 행렬의 element-wise inverse 관계를 수학적으로 증명하고 직교 성질 AB=I 관계를 유도했다.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2002년도 춘계학술대회 논문집
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• pp.856-860
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• 2002

The main objective of this study is to consider the effect of fatigue crack behavior on the variable depth of micro hole defects in SM20C at the symmetric position. The fatigue crack propagation test is performed by rotary bending fatigue test machine. The relationship between crack length(2a), cycles(N) and crack growth rate(da/dN) are investigated in this study. The result from the rotary bending fatigue test under the applied stress at 250MPa turned out that the fatigue life illustrated almost constant when the depth of symmetric micro hole deflects is both part A and B at the hope depth(h) = 0.5mm.