• 로봇학회논문지
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• 제17권4호
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• pp.493-499
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• 2022

This paper presents the design for the kinematic structure of a system for an automatically moored 6000 ton autonomous ship in a port, and the process and results of optimal design for the link cross-sectional shape. We propose an automatic mooring system with a PPP type serial manipulator structure capable of linear motion in the XYZ axis. The mooring force applied by the mooring system was derived with dynamics simulation tool "ADAMS". The design goal is the minimization of the cross-sectional area of the link. Constrains include compressive stress and shear stress. The optimization problems were solved by using the sequential quadratic programing method implemented in the fmincon package. The shape of the cross section was assumed to be rectangle. Through future research, we plan to manufacture automatic mooring system for 6000ton class autonomous ship.

• International Journal of Aerospace System Engineering
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• 제8권2호
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• pp.1-3
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• 2021

This study proposed a specific preliminary structural design procedure of the main wing for a small scale WIG vehicle to meet the target weight of the system requirement. The high stiffness and strength Carbon-Epoxy material was used for lightness, and the foam sandwich type structure at the upper skin and the spar webs was adopted for improvement of structural stability. After structural design, wing joint part was designed. Through investigation on structural design result, design modification was performed. After design modification, even thought the designed wing weight was a little bit heavier than the target wing weight, the structural safety and stability of the final design feature was confirmed.

• 대한기계학회논문집 C: 기술과 교육
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• 제5권2호
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• pp.127-134
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• 2017

원자로내부구조물은 다양한 진동하중조건에서 안전성과 건전성을 유지해야한다. 그러므로 미국원자력규제 위원회는 펌프 압력 맥동에 의한 진동을 포함하여 음향으로 유발되는 진동을 평가하기 위한 규제지침서 1.20을 제시하고 있다. 본 논문은 음향-구조 연성해석 기법을 사용하여 펌프 맥동 가진으로 인한 해석을 위해 노심지지배럴 주변의 유체와 구조의 연성을 고려하여 해석하는 방법론을 제안하였다. 해석결과는 미국 Palo Verde 1호기 종합진동평가 프로그램 발전소 시험결과와 잘 일치한다. 따라서 제안된 해석 방법론은 펌프 압력맥동에 대한 노심지지배럴의 구조응답을 평가하기 위한 효과적 방법으로 판단된다.

• Structural Engineering and Mechanics
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• 제61권6호
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• pp.701-709
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• 2017

Seismic dissipation devices can play a crucial role in mitigating earthquake damages, loss of life and post-event repair and downtime costs. This research investigates the use of ring springs with high-force-to-volume (HF2V) dissipaters to create damage-free, recentring connections and structures. HF2V devices are passive rate-dependent extrusion-based devices with high energy absorption characteristics. Ring springs are passive energy dissipation devices with high self-centring capability to reduce the residual displacements. Dynamic behaviour of a system with nonlinear structural stiffness and supplemental hybrid damping via HF2V devices and ring spring dampers is used to investigate the design space and potential. HF2V devices are modelled with design forces equal to 5% and 10% of seismic weight and ring springs are modelled with loading stiffness values of 20% and 40% of initial structural stiffness and respective unloading stiffness of 7% and 14% of structural stiffness (equivalent to 35% of their loading stiffness). Using a suite of 20 design level earthquake ground motions, nonlinear response spectra for 8 different configurations are generated. Results show up to 50% reduction in peak displacements and greater than 80% reduction in residual displacements of augmented structure compared to the baseline structure. These gains come at a cost of a significant rise in the base shear values up to 200% mainly as a result of the force contributed by the supplemental devices.

• 한국자동차공학회논문집
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• 제15권3호
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• pp.63-71
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• 2007

During the design phase of a product, reliability and design engineers are called upon to evaluate the reliability of the system, The question of how to meet target reliability for the system arises when estimated reliability or cost is inadequate. This then becomes a problem of reliability allocation and system structure design. This study proposes the optimization methodology to achieve target reliability with minimum cost through construction of the cost function of system. In cost function, total cost means the sum of initial cost, repair cost and maintenance cost. This study constructs optimization problem about system structure design and reliability allocation using cost function. This problem constructed is solved by Multi-island Genetic Algorithm(MIGA), and applies to urban transit brake system. Current brake system of the urban transit is series system. Series system is the simplest and perhaps one of the most common system, but it demands high reliability and maintenance cost because all components must be operating to ensure system operation. Thus this study makes a comparative study by applying k-out-of-n system to brake system. This methodology presented can be a great tool for aiding reliability and design engineers in their decision-makings.

• 제어로봇시스템학회:학술대회논문집
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• 제어로봇시스템학회 2003년도 ICCAS
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• pp.2246-2251
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• 2003

This paper proposes shape design of frame structures for vibration suppression and weight reduction. The $H_{\infty}$ norm of the transfer function from disturbance sources to the output points where vibration should be suppressed, is adopted as the performance index to represent the magnitude of vibration transfer. The design parameters are the node positions of the frame structure, on which constraints are imposed so that the structure achieves given tasks. For computation of Pareto optimal solutions to the two-objective design problem, a number of linear combinations of the $H_{\infty}$ norm and the total weight of the structure are considered and minimized. For minimization of the scalared objective function, a Lagrange function is defined by the objective function and the imposed constraints on the design parameters. The solution for which the Lagrange function satisfies the Karush-Kuhn-Tucker condition, is searched by the sequential quadratic programming (SQP) method. Numerical examples are presented to demonstrate the effectiveness of the proposed design method.

• Journal of Mechanical Science and Technology
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• 제17권12호
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• pp.1912-1921
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• 2003

This paper presents a global mode modeling of space structures and a control scheme from the practical point of view. Since the size of the satellite has become bigger and the accuracy of attitude control more strictly required, it is necessary to consider the structural flexibility of the spacecraft. Although it is well known that the finite element (FE) model can accurately model the flexibility of the satellite, there are associated problems : FE model has the system matrix with high order and does not provide any physical insights, and is available only after all structural features have been decided. Therefore, it is almost impossible to design attitude and orbit controller using FE model unless the structural features are in place. In order to deal with this problem, the control design scheme with the global mode (GM) model is suggested. This paper describes a flexible structure modeling and three-axis controller design process and demonstrates the adequate performance of the design with respect to the maneuverability by applying it to a large flexible spacecraft model.

• 한국정밀공학회지
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• 제20권9호
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• pp.180-187
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• 2003

In engineering design environment it is hard to link design data and systems because the types of them are disparate. Therefore, the importance of metadata has increased. Some researches have been executed to develop metadata. But they cannot interact with other metadata and are difficult to extend. The purpose of this paper is to develop a common document structure which represents the general information of mechanical part assembly using XML, and to use it as base documents in order to integrate design data and systems. It is composed of part, assembly and user documents. Part document represents the information of a part independently to part type. Assembly document represents the location of constituent part documents. User document represents user's information. Common documents can be used as a broker between design data and systems, and it can improve the interpretability and reusability of document. We applied the developed common document structure to 2-stage spur gear drive.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2002년도 추계학술대회 논문집
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• pp.359-364
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• 2002

In engineering design environment it is hard to link design data and system because the types of them are disparate. Therefore, the importance of metadata has increased. Some researches have been executed to develop metadata. But they cannot interact with other metadata and are difficult to extend. The purpose of this paper is to develop a common metadata structure which represents the general information of mechanical part assembly using XML, and to use it as base documents in order to integrate design data and systems. It is composed of part and assembly documents. Part document represents the information of a part independently to part type. Assembly document represents the location of part documents which compose an assembly. Common documents can be used as a broker between design data and systems and improve interpretability and reusability of document. We applied the developed common document structure to 2-stage spur gear drive.

• 한국복합재료학회:학술대회논문집
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• 한국복합재료학회 2002년도 추계학술발표대회 논문집
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• pp.1-4
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• 2002

The present study aims to design a multiplayer microstrip antenna with composite sandwich construction and to estimate structural behavior of this multiplayer structure for the next generation of structural surface technology. This is termed Surface-Antenna-Structure indicating that structural surface becomes antenna. Constituent materials were selected considering electrical properties as well as mechanical properties. For the antenna performance, antenna elements inserted into structural layers were designed for satellite communication at a resonant frequency of 12.5 GHz and final demonstration article was $16\times16$ array antenna. From electrical measurements it was shown that antenna performances were in good agreement with design requirements. Structural analysis showed this antenna structure was well designed for the mechanical rigidity. All constituent materials were characterized independently. The SAS concept is the first serious attempt at integration for both antenna and composite engineers and promises innovative future communication technology.