• 충청수학회지
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• 제16권2호
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• pp.59-73
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• 2003

Throughout this paper, we denote that R is a near-ring and G an R-group. We initiate the study of R-substructures of G, representations of R on G, monogenic R-groups, faithful R-groups and faithful D.G. representations of near-rings. Next, we investigate some properties of monogenic near-ring groups, faithful monogenic near-ring groups, monogenic and faithful D.G. representations in near-rings.

• 한국수학교육학회지시리즈B:순수및응용수학
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• 제18권4호
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• pp.305-312
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• 2011

In this paper, we denote that R is a near-ring and G an R-group. We initiate the study of the substructures of R and G. Next, we investigate some properties of R-groups, d.g. near-rings and monogenic (R, S)-groups.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 1997년도 추계학술대회논문집; 한국과학기술회관; 6 Nov. 1997
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• pp.88-95
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• 1997

In this paper, we present an efficient method for finite element vibration analysis of constantly rotating blade disks which are deformed to some considerable extent by centrifugal force, Coriolis force and operating load, and vibrate due to several types of exciting forces. A blade disk which is a structure with cyclic symmetry is divided into substructures with the same geometry. Only one substructure is modeled and can be analysed rapidly and exactly using discrete Fourier transform by means of a computer with small memory.

• 천문학회보
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• 제43권2호
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• pp.37.1-37.1
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• 2018

ZwCL 1447.2+2619 is a merging galaxy cluster at z=0.37 with clear substructures in X-ray emission and galaxy distribution. In addition, the system possesses distinct radio relics. In order to constrain the merger scenario, it is necessary to measure both the distribution and mass of the cluster dark matter. We perform a weak lensing analysis of ZwCL 1447.2+2619 using Subaru imaging data. After carefully addressing instrumental systematics, we detect significant lensing signals. In this talk, our methodology, weak lensing results, and possible merging scenarios will be presented.

• 한국농공학회지
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• 제30권3호
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• pp.82-94
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• 1988

A growing attention has been paid to the optimum design of structures in recent years. Most studies on the optimum design of reinforced concrete structures has been mainly focussed to the design of structural members such as beams, slabs and columns, and there exist few studies that deal with the optimum design of large-scale concrete shell structures. The purpose of the present investigation is, therefore, to set up an efficient optimum design method for the large-scale reinforced concrete cylindrical shell structures like intake tower of reservoir. The major design variables are the dimensions and steel areas of each member of structures. The construction cost which is compo8ed of the concrete, steel, and form work costs, respectively, is taken as the objective function. The constraint equations for the design of intake-tower are derived on the basis of strength design method. The results obtained are summarized as follows 1. The efficient optimlzation algorithrns which can execute the automatic optimum design of reinforced concrete intake tower based on the strength design method were developed. 2. Since the objective function and design variables were converged to their optimum values within the first or second iteration, the optimization algorithms developed in this study seem to be efficient and stable. 3. When using the strength design method, the construction cost could be saved about 9% compared with working stress design method. Therefore, the reliability of algorithm was proved. 4. The difference in construction cost between the optimum designs with substructures and with entire structure was found to be small and thus the optimum design with substructures may conveniently be used in practical design. 5. The major active constraints of each structural member were found to be the 'bending moment constraint for slab, the minimum longitudinal steel ratio constraint for tower body and the shearing force, bending moment and maximum eccentricity constraints for footing, respectively. 6. The computer program developed in the present study can be effectively used even by an uneiperienced designer for the optimum design of reinforced concrete intake-tower on the basis of strength design method.

• 한국음향학회지
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• 제34권5호
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• pp.360-370
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• 2015

무한 길이를 가진 도파관 구조물에 유한 길이를 가진 구조물이 결합되어 있는 경우, 결합된 구조물의 응답을 수치해석으로 구하기 위해서는 파동 방법과 모드 방법을 함께 적용하여 해석하는 것이 필요하다. 본 논문에서는 무한 길이 도파관구조물에 대해서는 파수유한요소법을, 유한 길이 구조물에 대해서는 유한요소법을 적용하여 결합 지점에서의 각 하부 구조물 임피던스 또는 모빌리티를 구하고 이를 연성하여 전체 구조물의 응답을 해석하는 방법에 대하여 다루었다. 해석 대상 구조물로는 내부에 사각 평판 구조물이 네 꼭지점에서 결합되어 있는 무한 길이 원통형 실린더를 선정하였으며, 네 결합지점이 강결합 또는 탄성마운트로 결합된 경우에 대하여 살펴보았다. 본 연구를 통해 임피던스 연성을 통한 파동 방법(파수유한요소법)과 모드 방법(유한요소법)의 결합이 적용 가능함을 확인하였다.

• Advances in aircraft and spacecraft science
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• 제5권1호
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• pp.1-19
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• 2018

The present work shows many aspects concerning the use of a numerical wave-based methodology for the computation of the structural response of periodic structures, focusing on cylinders. Taking into account the periodicity of the system, the Bloch-Floquet theorem can be applied leading to an eigenvalue problem, whose solutions are the waves propagation constants and wavemodes of the periodic structure. Two different approaches are presented, instead, for computing the forced response of stiffened structures. The first one, dealing with a Wave Finite Element (WFE) methodology, proved to drastically reduce the problem size in terms of degrees of freedom, with respect to more mature techniques such as the classic FEM. The other approach presented enables the use of the previous technique even when the whole structure can not be considered as periodic. This is the case when two waveguides are connected through one or more joints and/or different waveguides are connected each other. Any approach presented can deal with deterministic excitations and responses in any point. The results show a good agreement with FEM full models. The drastic reduction of DoF (degrees of freedom) is evident, even more when the number of repetitive substructures is high and the substructures itself is modelled in order to get the lowest number of DoF at the boundaries.

• 대한기계학회논문집
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• 제19권6호
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• pp.1490-1500
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• 1995

Compression molding of SMC (Sheet Molding Compound) in a thin plaque with substructures like a rib is involved with the formation of surface defect along the centerline over the rib area called by sink mark depending on process parameters. The surface quality of the external panels in automotive manufacturing is so critical that this kind of defect should be eliminated during manufacturing stages. The effect of process parameters on sink mark formation and the distribution of chopped fiberglasses in the compression molded thin plaque with a rib was experimentally investigated in the present study. In order to estimate the effect of the molding parameters such as molding temperature, mold closing speed, depth of the rib, corner radius of the rib, and final molded part thickness of flat portion on the depth of sink mark and the distribution of fiberglasses in the molded SMC part with the rib under the present experimental conditions, the molding parameters used in experiments were non-dimensionalized equation for predicting the depth of sink mark was determined through dimensional analysis based on the experimental data. The orientation and distribution of fiberglasses and fillers which directly affect the formation and depth of sink mark were investigated by taking the photographs of the cross-sectional area of the molded specimen using scanning electron microscope. The experimental results proposed from this investigation are useful in understanding the formation of sink mark and predicting the depth of sink mark in compression molding of SMC with substructures.

• 한국도로학회논문집
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• 제11권2호
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• pp.239-247
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• 2009

매설관은 기존 포장의 제거와 굴착후 다짐 및 재포장에 의해 시공되며 주변지반의 침하와 균열, 재포장부의 침하발생과 평탄성 저하를 초래한다. 본 연구에서는 매설관의 설치와 뒷채움재의 다짐 및 재포장 등 일련의 시공과정에서 간과되고 있는 포장하부구조의 물성치 획득방법으로서 공내재하시험 및 동평판재하시험을 채택하였다. 공내재하시험 비교 결과, 관매설 및 새로운 뒷채움재의 다짐으로 인해 충분한 하부지반 강성이 굴착전에 비하여 획득되지 못함을 확인하였다. 재포장층의 두께는 기존층에 비하여 더 두껍게 설계되어야 함을 의미한다. 동평판시험은 공내재하시험에 비하여 층표면 강성을 파악하기에는 효과적이지만 매설관의 하부구성층 또는 뒷채움재 등의 전체 강성 또는 다짐도를 정확히 파악할 수 없음을 확인하였다.

• 콘크리트학회논문집
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• 제27권1호
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• pp.55-63
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• 2015

사전제작 기술은 교량을 더 안전하고 주변과 친화적인 환경을 구축하며 작업 환경에 제한이 있을 경우에도 품질과 내구성을 개선하며 공사를 수행할 수 있다. 콘크리트 충전강관을 이용한 모듈러 하부구조 교각을 제안하였다. 프리캐스트 피어캡은 피어테이블과 프리스트레스를 도입한 프리캐스트 세그먼트로 구성되어 있다. 피어테이블은 매입형 강재를 사용하여 응력의 집중을 완화하였다. 피어캡과 교각은 4개 또는 6개의 CFT기둥으로 연결된다. 피어캡의 전단강도는 피어테이블에서 연장시킨 전단 스터럽에 의해 저항하게 된다. 횡방향 프리스트레스 힘은 사용하중에 의한 인장 응력을 제어하기 위하여 도입되었다. 이 논문에서는 모듈러 구조의 유효성을 정적실험을 통하여 평가하였다. 제안된 피어캡은 설계 요구사항들을 연속 철근과 프리스트레스에 의해 만족시켰다. 모듈러 구조의 표준화는 급속교체 및 교량의 급속시공에 효과적으로 사용될 수 있다.