• Journal of Ocean Engineering and Technology
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• v.14 no.2
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• pp.112-116
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• 2000

To determine a preliminary hull form with a minimum viscous resistance this study considers the systematic variations of full form and calculations of the viscous resistance for varied hull forms. A preliminary hull form can be determined from a parametric study of viscous resistance.

• Journal of the Korean Institute of Intelligent Systems
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• v.17 no.2
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• pp.154-159
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• 2007

Wake distribution data of stem flow fields have been accumulated systematically by model tests. If the correlation between geometrical hull information and wake distribution is grasped through the accumulated data, this correlation can be helpful to designing similar ships. In this paper, Neuro-Fuzzy system that is emerging as a new knowledge over a wide range of fields nowadays is tried to estimate the wake distribution on the propeller plan. Neuro-Fuzzy system is well known as one of prospective and representative analysis method for prediction, classification, diagnosis of real complicated world problem, and it is widely applied even in the engineering fields. For this study three-dimensional stern hull forms and nominal wake values from a model test ate structured as processing elements of input and output layer, respectively. The proposed method is proved as an useful technique in ship design by comparing measured wake distribution with predicted wake distribution.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.38 no.5
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• pp.467-476
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• 2010

For the very light jet aircraft design, the design baseline configuration has been selected using the logical decision making process, and the design optimization problem is formulated by considering the airworthiness regulations as design constraints. Airworthiness regulations are the minimum requirements for the safe aircraft flight and must be considered from the conceptual design stage. After carefully selecting the airworthiness constraints and the user specified requirements, a series of design making models including the affinity diagram, nested column diagram, quality function deployment (QFD), Pugh concept selection matrix, are used to find and evaluate alternative configuration baselines. From the feasible design space searching process, the best altenative design, which satisfies the airworthiness constraints while excluding the user subjective decisions as much as possible, has been successfully derived.

• Journal of the Society of Naval Architects of Korea
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• v.36 no.2
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• pp.72-76
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• 1999

To predict the maneuverabiliy of a ship, it is most reliable to carry out the model tests for the ship. But, at the initial design stage of ships, scene other methods of predicting the overall maneuverabiliy of ships with confined data, like principal dimensions and propeller and rudder characteristics, are required. In this paper, the authors suggested new formulas for the linear derivatives of the sway force and yaw moment, based on the captive model test carried out by the Japanese researchers. These formulas can account the effects of stern frame line shape and stern profile, when assessing the maneuverability of ships. The usefulness of the formulas are discussed by comparing the simulations with the model tests.

• Journal of Korean Association for Spatial Structures
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• v.5 no.2 s.16
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• pp.47-55
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• 2005

The method to form the space of the pneumatic structures by internal pressure is classified greatly as the dual type with the nlty type. The shape of the pneumatic structures consists of the curved surface under uniform tension not greatly to be deformed by the design load and stress must not be concentrated also. Therefore, In this study, we have done the structural analysis of the unity typed pneumatic structures by the NASS which is the program for nonlinear analysis. The analytic model is a rectangular pneumatic membrane structures which have four side fixed edges. And we have done the nonlinear incremental analysis considering the orthotropic material.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.656-659
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• 2011

최근 우리나라뿐만 아니라 전 세계적으로 고층건물의 규모가 점점 커짐에 따라 고층 건물은 초기단계에서부터 막대한 자원과 비용이 발생하고 도중에 설계변경이 어렵거나 불가능한 경우가 많아졌다. 때문에 초기구조설계과정과 실시설계, 시공과정에서의 차이를 최대한 줄이는 것이 사업의 경제성을 좌우할 만큼 중요한 비중을 차지한다. 이러한 정보를 제대로 관리할 초고층 BIM 정보환경이 구축된다면 발주자 설계자 시공자가 얻게 될 이익은 결코 적지 않을 것이다. S-BIM 프로세스 상에서 철골조를 형성하기 위해서는 세 단계의 프로세스를 거치는데 구조 해석 및 설계 단계, 구조 해석 및 설계 결과 데이터베이스 구축, 철골구조설계 및 형상화 모듈에 의한 부재 생성이다. 본 연구에서는 구조해석 및 설계(Analysis and Design, A&D) 데이터베이스를 C#코딩을 통해 형상, 길이 및 위치 정보를 결정하는 데 필요한 정보를 모듈 상에 불러오고, 이를 이용한 부재의 치수, 길이, 좌표 값을 산정하였다. 모듈 결과 생성된 정보를 BIM 플랫폼 상에 모델링함으로써 사용자 입력 값을 최소로 하여 기존 BIM 플랫폼의 모델링 방법 대비, 생산성이 향상된 철골구조설계의 자동화를 구현해 보고자 하였다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.9
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• pp.723-734
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• 2018

A structural weight estimation methodology for the multicopter design process is presented. In general, a multicopter is composed of an airframe, motors, propellers, battery and so on. Among these, the weight of motors, propellers and battery can be obtained from the weight trends with respect to design parameters. However, the structural weight is hard to be estimated due to the various configurations and design concepts of multicopters. Moreover, the airframe weights of most commercial multicopter products are not provided. Thus, an accurate airframe weight model is required for the reliable mutlcopter design process. Firstly, the standard configuration of multicopters is defined. Then, we proposed the structural weight estimation method using the number and diameter of propellers determined from the initial step of sizing process. Finally, we validated our suggested method using the commerical products.

• Proceedings of the Korean Institute of Intelligent Systems Conference
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• 2006.11a
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• pp.193-196
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• 2006

프로펠러 회전면에서의 반류분포는 주로 모형시험에 의해서 규명되어 왔다. 이렇게 축적된 데이터베이스를 통해 선박의 기하학적 형상정보와 반류분포 사이의 입출력관계를 모델링할 수 있다. 면 선박 초기설계시 유사선종의 설계에 도움이 된다. 본 연구에서는 이들 입출력 사이의 관계를 뉴로퍼지시스템으로 모델링하고 학습한 후 새로운 입력에 대한 출력값의 검토를 통해 그 유용성을 확인한다.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.46 no.6
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• pp.452-463
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• 2018

Tip-jet gyroplane is a type of compound helicopter that employs the tip-jet system to rotate the rotor by a reaction force from the gas jetted at the rotor tips in hovering. In forward flight, tip-jet gyroplane converts into a form of a gyroplane. Therefore, it is necessary to develop a new conceptual design method to consider three flight modes: tip-jet mode, gyroplane mode, and transient mode. This study developed the numerical code of conceptual design methodology that can consider three flight modes. The developed code was validated against the available experiment data. Based on the developed code, initial sizing of tip-jet gyroplane was performed for two mission profiles including high speed forward flight of 150knots with a mission range of 300km or 400km. Subsequently, the configuration and performance of the 3,000lb tip-jet gyroplane were analyzed.

• Journal of the Computational Structural Engineering Institute of Korea
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• v.25 no.1
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• pp.73-80
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• 2012

It is important to design the optimal shape in the initial process because the influences on the design and construction are large according to the shape and pattern of spatial structures. However, the existing optimal shape designs for spatial structure are performed by the designer's intuition and experiences. Therefore, this study proposes the integrated process using the topology optimization and cellular automata model. First, the initial optimal shapes are obtained by using the topology optimization, and then the spatial truss structural patterns are created through the application of cellular automata rules. Finally, the optimal shapes to satisfy the various design conditions are generated by the structural analysis and size optimization.