• 드라이브 ㆍ 컨트롤
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• 제16권2호
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• pp.8-14
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• 2019

A typical gantry crane is generally used to lift and transport objects in various workplaces. Most of the supporting structures in a gantry crane are fixed on the ground while the moving hoist is running overhead along the girder. There are some disadvantages to its long installation time and high installation cost. Therefore, a hydraulic based gantry crane was studied to solve the issues of typical gantry cranes. The supporting structure of the proposed gantry crane consisted of a hydraulic cylinder and telescopic boom. The dimension of the proposed gantry crane can be decreased due to its simplified structure. The analytical and theoretical methods were used to verify the structural stability of the proposed crane. The most severe load condition was considered for the analysis, and the stress and deflection of the structure are analyzed. The simulation results were as expected from the theoretical analysis. Finally, the structural and dynamic safety of the proposed hydraulic based gantry crane was validated. The obtained results can be used as guidelines in the design process of the hydraulic based gantry crane.

• Earthquakes and Structures
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• 제1권1호
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• pp.43-67
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• 2010

A gradient-based evolutionary optimization methodology is presented for finding the optimal design of both the added dampers and their supporting members to minimize an objective function of a linear multi-storey structure subjected to the critical ground acceleration. The objective function is taken as the sum of the stochastic interstorey drifts. A frequency-dependent viscoelastic damper and the supporting member are treated as a vibration control device. Due to the added stiffness by the supplemental viscoelastic damper, the variable critical excitation needs to be updated simultaneously within the evolutionary phase of the optimal damper placement. Two different models of the entire damper unit are investigated. The first model is a detailed model referred to as "the 3N model" where the relative displacement in each component (i.e., the spring and the dashpot) of the damper unit is defined. The second model is a simpler model referred to as "the N model" where the entire damper unit is converted into an equivalent frequency-dependent Kelvin-Voigt model. Numerical analyses for 3 and 10-storey building models are conducted to investigate the characters of the optimal design using these models and to examine the validity of the proposed technique.

• Structural Engineering and Mechanics
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• 제50권6호
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• pp.797-816
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• 2014

Cooling tower is analyzed as an assembly of layered nonlinear shell elements. Geometric representation of the shell is enabled through layered nonlinear shell elements to define the different layers of reinforcements and concrete by considering the material nonlinearity of each layer for the cooling tower shell. Modal analysis using Ritz vector analysis and nonlinear time history analysis by direct integration method have been carried out to study the effects of the inclination of the supporting columns of the cooling tower shell on its dynamic characteristics. The cooling tower is supported by I-type columns and ${\Lambda}$-type columns supports having the different inclination angles. Relevant comparisons of the dynamic response of the structural system at the base level (at the junction of the column and shell), throat level and at the top of the tower have been made. Dynamic response of the cooling tower is found to be significantly sensitive to the change of the inclination of the supporting columns. It is also found that the stiffness of the structure system increases with increase in inclination angle of the supporting columns, resulting in decrease of the period of the structural system. The participation of the stiffness of the tower in structural response of the cooling tower is fund to be dependent of the change in the inclination angle and even in the types of the supporting columns.

• 대한조선학회논문집
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• 제46권3호
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• pp.362-371
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• 2009

Shipbuilding is a typical 'build to order' industry. It has a business model that generates revenues from building various ships and offshore products in accordance with owner's requirements at each production stage. Under uncertainty in shipping market, it is very essential for the shipbuilder to prepare the fast and competitive decision for product portfolio strategy in order to maximize contribution margin by exploiting production facilities and constraints. In this study, we introduce the unique decision supporting methodology for the optimal product portfolio sets based on Theory of Constraints(TOC). This methodology is established by adopting the concept of Drum Buffer Rope(DBR) in constraints planning and Throughput Accounting (TA) in management accounting of TOC. In addition, Decision Supporting System(DSS) is implemented. This DSS system provides a throughput estimator with reflecting the cost structure of shipbuilding industry and a resource simulator built on heuristic algorithms to operate major constraint-resources in shipyard such as dock, quay and pre-erection area etc. Several examples are presented to show that the proposed methodology and system can effectively support the strategic decision-making process of a global shipbuilding company.

• 한국정보과학회논문지:시스템및이론
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• 제29권4호
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• pp.232-243
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• 2002

TLB(translation lookaside buffer) 성능 향상을 위한 전형적인 방법으로 TLB로 하여금 더 많은 엔트리 수를 지원하는 방법, 페이지 크기를 증대시키는 방법, 그리고 다중 페이지 크기를 지원하는 방법이다. 현재 TLB 성능을 높이기 위한 가장 좋은 방법으로 다중 페이지 크기를 지원하는 연구가 효과적이다. 다중 페이지 크기를 지원하는 방법들 중에서 가장 적합한 것은 운영체제나 컴파일러로부터 일정한 정보를 받아서 가장 적합한 페이지 크기를 TLB에 할당하는 것이다. 그러나 운영체제의 시스템 영역에서 는 이러한 방식이 가능하나 사용자 영역에서는 현실적으로 이러한 방식을 지원하기 어렵기 때문에 우리는 사용자 영역까지 운영체제의 지원 없이 이중 페이지를 지원할 수 있는 새로운 TLB 구조를 제안하고자 한다. 고성능을 보장하기 위한 방법으로 이중페이지를 하드웨어 방식으로 지원하는 방식을 제시하고, 또한 저전력의 효과를 높이기 위하여 하나의 완전 연관 TLB를 두 개의 서버 TLB로 나누는 방식을 사용하였다. 이러한 두 가지 방식을 내장형 프로세서에 적합하도록 하나로 집적화 하여 저전력과 고성능의 효과를 모두 얻을 수 있었다. 시뮬레이션 결과에 따르면 적은 엔트리만을 사용하고도 높은 성능 향상효과를 얻을 수 있으며 또한 완전 연관 TLB에 비해 거의 50%이상 소비전력을 줄이는 효과를 얻을 수 있다.

• 한국공간구조학회논문집
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• 제19권4호
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• pp.27-34
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• 2019

Spatial structure does not have columns and walls installed inside, so they have a large space. There are upper structure and substructure supporting them. The response of seismic loads to the upper structure may be increased or decreased due to the effects of the substructure. Therefore, in this study, the seismic response of the upper structure and the floor response spectrum of the substructure were compared and analyzed according to the height of the substructure in the spatial structure where the LRB was installed. As a result, the possibility of amplification of response was confirmed as seismic waves passed though the substructure, which is likely to increase the response of the upper structures.

• KEPCO Journal on Electric Power and Energy
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• 제2권3호
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• pp.469-475
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• 2016

최근 석유 에너지 고갈의 문제에 봉착함에 따라 신재생 에너지, 즉 풍력 에너지 분야에 대한 연구가 자연스럽게 부각되고 있다. 그 중 해상풍력은 육상풍력에 비교해 바람 자원이 풍부하기 때문에 효율성 측면에서 주목 받고 있지만 전체 시스템의 설치비용에 따른 경제성이 중요한 문제가 되고 있다. 일반적으로 해상 풍력 사업의 구성비에서 지지구조물 설치비용의 비율이 통상 25% 이상을 차지하는 경향이 있으며, 설계된 지지구조에 대해 정확한 해석과 분석이 가능 하다면 설치 및 시공분야의 경제성을 확보하는데 중요한 역할을 할 수 있다. 본 연구에서는 해상 부유식 풍력발전시스템의 경제성 확보에 중요한 역할을 할 수 있는 석션버켓 기초의 지반연성 비선형 구조해석 기법을 구축하고 이에 대한 검증을 위해 실험결과와 비교검증을 수행하였다.

• 한국CDE학회논문집
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• 제14권1호
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• pp.33-41
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• 2009

Triangular mesh models are widely used in reverse engineering, computer graphics, rapid prototyping and NC(numerical controller) tool-path generation. Triangular mesh models are generated from point clouds, surface models and solid models. A halfedge-based triangular mesh data structure is proposed and the development considerations are presented. In the presented data structure, halfedge is the key data structure. Halfedge stores its triangle index and the order in the triangle. Triangles do not store the halfedge lists explicitly. Halfedge is referred by value and defined when it is required. Proposed data structure supports four design requirements: efficient rendering, compact memory, supporting efficient algorithms and easy programming.

• 한국CDE학회논문집
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• 제8권2호
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• pp.90-100
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• 2003

Engineering change (EC) objects are the data structure and related operations that can support applications for EC procedures or processes. Their functionalities include controlling management data, specifying related product structure, and archiving a history of product structure changes for EC management. In this paper we introduce a systematic approach to support the propagation of changes between different product structure views using the history of structure changes in EC objects. The change propagations supported by EC objects enable designers to maintain the consistency of multiple product structure views for engineering, manufacturing or even customer support applications. This paper also includes EC examples and experimental implementations for the proposed EC objects.

• Steel and Composite Structures
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• 제8권3호
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• pp.231-242
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• 2008

This paper presents results of fire tests on corrugated sheets used as load bearing structure of roofs of industrial buildings. Additional tests of bolted sheet connections to the supporting structure at ambient and elevated temperatures are described. Three connection types were tested and their resistance, stiffness and deformation capacity was evaluated. Finite element simulations of the corrugated sheet based on the experimental observations are briefly described and design models are presented.