• 대한수학회보
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• 제52권4호
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• pp.1069-1076
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• 2015

In this paper, a two species competitive model with stage structure and harvesting is investigated. By using the differential inequality theory, some new sufficient conditions which ensure the permanence of the system are established. Our result supplements the main results of Song and Chen [Global asymptotic stability of a two species competitive system with stage structure and harvesting, Commun. Nonlinear Sci. Numer. Simul. 19 (2001), 81-87].

• 소음진동
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• 제10권3호
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• pp.508-516
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• 2000

To study the possibility of F.E.M application to vibration and shock response of double stage elastic mounting system with complicated damped foundation structure like common-bed or raft in ships foundation structure model which has complicated damped sandwich cross-section is analyzed first. And then vibration responses experimental results and shock response of double stage elastic mounting system with complicated damped foundation structure like common-bed or raft in ships foundation structure model which adopts the above damped structure as intermediate foundation were compared. As a result it is found that F.E.M could be effectively used in analyzing the vibration and shock response of double and multi-stage elastic mounting system with complicated damped foundation structures.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.902-907
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• 2004

In this paper, a multi-step optimization using a G.A. (Genetic Algorithm) with variable penalty function is introduced to the structural design optimization of a 5-head route machine. Our design procedure consist of two design optimization stage. The first stage of the design optimization is static design optimization. The following stage is dynamic design optimization stage. In the static optimization stage, the static compliance and weight of the structure are minimized simultaneously under some dimensional constraints and deflection limits. On the other hand, the dynamic compliance and the weight of the machine structure are minimized simultaneously in the dynamic design optimization stage. As the results, dynamic compliance of the 5-head router machine was decreased by about 37％ and the weight of the structure was decreased by 4.48％ respectively compared with the simplified structure model.

• 대한조선학회논문집
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• 제43권3호
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• pp.362-374
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• 2006

Currently, all design information of a hull structure is being first defined on 2D drawings not 3D CAD model at the initial ship design stage and then transferred to following design stages through the 2D drawings. This is caused by the past design practice, limitation on time, and lack of hull structural CAD systems supporting the initial design stage. As a result, the following design tasks such as the process planning and scheduling are being manually performed using the 2D drawings. For solving this problem, a data structure supporting the initial design stage is proposed and a prototype system is developed based on the data structure. The applicability of the system is demonstrated by applying it to various examples. The results show that the system can be effectively used for generating the 3D CAD model of the hull structure at the initial design stage.

• Computers and Concrete
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• 제12권2호
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• pp.169-186
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• 2013

The aim of this paper is to determine the effect of soil-structure interaction and time dependent material properties on behavior of concrete box-girder highway bridges. Two different finite element analyses, one stage and construction stage, have been carried out on Komurhan Bridge between Elazi$\breve{g}$ and Malatya province of Turkey, over Fırat River. The one stage analysis assume that structure was built in a second and material properties of structure not change under different loads and site conditions during time. However, construction stage analysis considers that construction time and time dependent material properties. The main and side spans of bridge are 135 m and 76 m, respectively. The bridge had been constructed in 3 years between 1983 and 1986 by balanced cantilever construction method. The parameters of soil-structure interaction (SSI), time dependent material properties and construction method are taken into consideration in the construction stage analysis while SSI is single parameter taking into consideration in the one stage analysis. The 3D finite element model of bridge is created the commercial program of SAP2000. Time dependent material properties are elasticity modulus, creep and shrinkage for concrete and relaxation for steel. Soft, medium, and firm soils are selected for evaluating SSI in both analyses. The results of two different finite element analyses are compared with each other. It is seen that both construction stage and SSI have a remarkable effect on the structural behavior of the bridge.

• Journal of applied mathematics & informatics
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• 제28권5_6호
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• pp.1379-1393
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• 2010

In this paper, a stage-structured predator prey model (stage structure on prey) with two discrete time delays has been discussed. The two discrete time delays occur due to maturation delay and gestation delay. Linear stability analysis for both non-delay as well as with delays reveals that certain thresholds have to be maintained for coexistence. Numerical simulation shows that the system exhibits Hopf bifurcation, resulting in a stable limit cycle.

• 대한안전경영과학회지
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• 제17권2호
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• pp.235-240
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• 2015

Using a progressive die of the multi-stage drawing product, It was experiments for the Influence of the Products Roundness on the die pad process Safety die model, obstacle countermeasure research safety die design When the die pad is independent structure, Sidewall thickness of the inside 2stage, 3stage, 4stage of the product is thicker, the thickness of the inside 1stage and the bottom is thinner. it was become unstable beacuse the inside 1stage related to the Products Roundness is thinner. When the die pad is Integrated structure, Sidewall thickness of the inside 1stage, 2stage of the product is thicker, and Sidewall 3stage and 4stage was a thin. it was become unstable beacuse the inside 3stage related to the Products Roundness is thinner. Therefore, The appropriate combination of and integrated independent is required for each process.

• Geomechanics and Engineering
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• 제22권3호
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• pp.265-275
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• 2020

As a flexible supporting structure, the anchoring frame structure is widely adopted to support multistage slopes in high earthquake-intensity area for its effectiveness and practicality. The previous study indicates that the anchor of anchoring frame structure is the most likely to be damaged during earthquakes. It is crucial to determine the pull-out capacity of anchor against seismic force for the seismic design of anchoring frame structure. In this study, an analytical model of a three-stage slope supported by anchoring frame structure is established, and the upper bound method of limit analysis is applied to deduce the seismic anchor force of anchoring frame structure. The pull-out capacity of anchor against seismic force of anchoring frame structure at each stage is obtained by computer programming. The proposed method is proved to be reasonable and effective compared with the existing published solution. Besides, the influence of main parameters on the pull-out capacity of anchor against seismic force is analyzed to provide some recommendations for the seismic design of anchoring frame structure.

• KIEAE Journal
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• 제11권4호
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• pp.87-94
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• 2011

This study was suggested to develop sustainable durability design system and proposed the plan to evaluate design conditions that meet the intended service life and $LCCO_{2}$ reduction level of reinforced concrete structure easily from the early design stage. For that the W/B and covering depth of the concrete structure were calculated through calculation of service life based on standard specification expression and the quantitative reduction rate of the vertical member of reinforced concrete structure by the calculated W/B was applied. Life cycle of building classified into construction stage, operation stage, maintenance stage, and demolition/disposal stage and the method of $CO_{2}$ evaluation of each stage was proposed. For construction stage, the major construction materials that take up over 80% $CO_{2}$ emitting during building construction were selected and the $CO_{2}$ evaluation method for 5 standard apartment houses was proposed. Also, for operation stage, $CO_{2}$ emission was calculated through calculation of heating load by energy efficiency rating certification system. For maintenance stage, $CO_{2}$ emission was calculated using concept of re-construction by life and for demolition/disposal stage was calculated with the use of construction standard estimate. As a result of the case study by such evaluation methods, 80 years of service life and 17 specifications of sustainable durability design that meet the 40% intended $LCCO_{2}$ reduction level were deduced. The Maximum $LCCO_{2}$ reduction rate was analyzed by 47.2%.

• 환경생물
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• 제23권2호
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• pp.141-145
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• 2005

본 연구는 전나무림 생태계 이해를 위하여 전나무 임분구조에 관한 기초자료를 수집하는 조사의 일부이다. Leibundgut(1981)의 임분구조 분류에 따르면 A,B임분은 쇠퇴기로 추정되며 C는 갱신기, D는 안정기와 쇠퇴기 복합형, E는 불안정한 시기인 택벌상으로 추정된다.