• Journal of the Society of Naval Architects of Korea
• /
• v.28 no.2
• /
• pp.52-68
• /
• 1991

A new propeller series is developed using the newly developed blade section(KH18 section) which behaves better cavitation characteristics and higher lift-drag ratio at wide range of angle-of-attack. The pitch and camber distributions are disigned in order to have the same radial and chordwise loading distribution with the selected circumferentially averaged wake input. Since the geometries of the series propeller, such as chord length, thickness, skew and rate distribations, are selected by regression of the recent full scale propeller geometric data, the performance prediction of a propeller at preliminary design stage can be mure realistic. Number of blades of the series propellers is 4 and the expanded blade area ratios are 0.3, 0.45, 0.6 and 0.75. Mean pitch ratios are selected as 0.5, 0.65, 0.8, 0.75 and 1.1 for each expanded area ratio. The new propeller series is composed of 20 propellers and is named as KD(KRISO-DAEWOO) propeller series. Propeller open water tests are performed at the experimental towing tank, and the cavitation observation tests and fluctuating pressure measurements are carried out at the cavitation tunnel of KRISO. $B_{P}-\delta$ curves, which can be used to select the optimum propeller diameter at the preliminary design stage, are derived from a regression analysis of the propeller often water test results. The KD-cavitation chart is derived from the cavitation observation test results by choosing the local maximum lift coefficient and the local cavitation number as parameters. The caviy extent of a propeller can be predicted more accurately by using the KD-cavitation chart at a preliminary design stage, since it is derived from the results of the cavitation observation tests in the selected ship's wake, whereas the existing cavitation charts, such as the Burrill's cavitation chart, are derived from the test results in uniform flow.

• Computational Structural Engineering
• /
• v.4 no.1
• /
• pp.32-35
• /
• 1991

본 고에서는 막구조 해석.설계시의 주요 내용을 각 해석단계별로 간략히 소개하였다. 막구조는 막이론 자신이 가진 근사성, 요소의 탄성 특성의 근사, 막면 요소로 곡면을 나타내는 기하학적 근사 등으로 구조물의 형태, 막재료의 동특성에 따라 해석시 오차가 발생하게 되며, 또한 구조설계 단계에서 막 판넬 제작 및 시공에 대한 고려가 되지 않으면 그 오차는 더욱 크게 된다. 따라서 향후, 보다 정확한 막구조의 설계를 위해서는 섬유직포에 코팅한 막재의 역학적 특성을 보다 잘 표현할 수 있는 막재모델의 정식화, 막재단도 해석시 무장력 상태의 설계곡면을 구하는 방법, 막판넬을 접합하고, 장력을 도입하는 시공과정을 고려한 실초기 평형상태 및 시공과정 해석법에 대한 연구가 계속 되어야 한다. 또한 초기형상 해석에서 시공과정 해석까지 전 설계과정을 공통 Data Base에서 일관 작업이 가능하도록 막구조통합 설계 System의 개발이 필요하다.

• Journal of the Korean Magnetics Society
• /
• v.27 no.2
• /
• pp.54-62
• /
• 2017

This paper presents a design of the Interior Permanent Magnet Synchronous Motor (IPMSM). an initial design process is accomplished by using the parametric design. In the design process, motor characteristics of parameters is computed by the d-q axis equivalent circuit model. Then, an optimal design process is accomplished by combination the experimental design and the response surface method. Finally, the design and analysis results are verified with experimental results.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.22 no.5
• /
• pp.128-135
• /
• 2021

Thin-walled tubes have been widely used as energy absorbing devices because they are light and have high energy-absorption efficiency. However, the downside is that conventional thin-walled tubes usually exhibit an excessive initial peak crushing force (IPCF) and a large fluctuation in the load-displacement curve, and thus lack stability as energy absorbing devices. Corrugated tubes were introduced to reduce IPCF and to increase the stability of collision energy-absorbing devices. Since the performance of corrugated tubes is highly influence by geometry, design optimization methods can be utilized to optimize the performance of corrugated tubes. In this paper, we utilize shape design optimization based on an adaptive surrogate model for crashworthiness analysis. The amplitude and wavelength of the corrugation, as well as curvature changes in the features, are the design variables. A morphing methodology is adopted to perform shape design parameterization. Through numerical examples, we compare optimal design results based on the adaptive surrogate model, with optimal results based on conventional surrogate models, and we show that direct optimal design methods produce more efficient results.

• Proceedings of the KIEE Conference
• /
• 2015.07a
• /
• pp.1062-1063
• /
• 2015

오프 그리드 형태의 소형풍력발전기는 도심지 또는 사람이 거주하는 지역에 설치되므로 소음, 진동, 안전성 등에 많은 문제가 야기되고 있다. 풍력발전기 내부적으로 소음 및 진동에 가장 큰 영향을 미치는 요소는 코깅토크로 발전기 회전자가 회전할 때 고정자 슬롯과 회전자 영구자석 사이 공극 릴럭턴스 변화에 의해 발생한다. 또한, 코깅토크는 풍력발전기의 초기 기동 풍속에 영향을 미치며, 토크리플 증가의 원인이 되어 코깅토크 저감 설계는 소형풍력발전기 설계에서 필수적으로 이루어져야 한다. 본 논문에서는 실험계획법을 진행하여 이중고정자 발전기의 영구자석 형상 최적화 설계를 통해 코깅토크를 저감 설계를 실시하였으며, 추가적으로 발전기 출력 전압 고조파 발생을 저감시켰다.

• Journal of Korean Association for Spatial Structures
• /
• v.7 no.3 s.25
• /
• pp.57-66
• /
• 2007

The membrane structures, a kind of lightweight soft structural system, are used for spatial structures. The material property of the membrane has strong axial stiffness, but little bending stiffness. The design procedure of membrane structures are needed to do shape finding, stress-deformation analysis and cutting pattern generation. In shape finding, membrane structures are unstable structures initially. These soft structures need to be introduced initial stresses because of its initial unstable state, and happen large deformation phenomenon. Therefore, in this paper, we investigate the convergence of solution and the speed according to the control variables and the method of shape analysis.

• Proceedings of the KIEE Conference
• /
• 2005.04a
• /
• pp.247-249
• /
• 2005

UTM-02 모델의 초기형상을 기반으로 차체 프레임 구조물에 대한 경량화 설계를 수행하였다. 전체 프레임을 14개의 부재로 나누었으며, 부재 두께를 설계변수로 정하였다. 효율적인 설계최적화를 수행하기 위하여 반응면기법을 이용하였다. 반응면기법을 통해 근사된 목적함수와 제한조건을 이용하여 최적화를 수행하였으며 각 설계변수들에 대한 감도도 산출하였다.

• Magazine of the Korea Concrete Institute
• /
• v.20 no.6
• /
• pp.28-35
• /
• 2008

The Burj Dubai Project will be the tallest structure ever built by man; when completed the tower will be more than 700 meter tall and more than 160 floors. While the early integration of aerodynamic shaping and wind engineering considerations played a major role in the architectural massing and design of this multi-use/residential tower, where mitigating and taming the dynamic wind effects was one of the most important design criteria, the material selection for the structural systems of the tower was also a major consideration and required detailed evaluation of the material technologies and skilled labor available in the market at the time Concrete was selected for its strength, stiffness, damping, redundancy, moldability, free fireproofing, speed of construction, and cost effectiveness. In addition, the design challenges of using concrete for the design of the structural system components will be addressed. The focus on this paper will also be on the early planning of the concrete works of the Burj Dubai Project.

• Journal of the Korea Academia-Industrial cooperation Society
• /
• v.20 no.12
• /
• pp.475-481
• /
• 2019

The importance of performance-based design feedback is being emphasized when it comes to the potential impact that affects all the lifecycle of the building. However, the latency and disconnection of domain expert in the sector of AEC/FM remain current obstacles between design and performance feedback. It is hard to utilize performance feedback information for design exploration and support design decision making during the conceptual phase of design. Using parametric design, this paper proposes various design alternatives from a set of rules and constraints defined by algorithms for the geometric configurations of an Office Building. A Building Performance Analysis (BPA) was to developed using Autodesk® Revit® 2019 which integrates Autodesk® Green Building Studio® to predict its sufficient daylighting conditions of the LEED v4's Daylighting Autonomy (DA). The parametric-based performance feedback of this study outlines potential design improvements for further exploration in application to the early design process.

• Transactions of the Korean Society of Mechanical Engineers A
• /
• v.36 no.8
• /
• pp.897-904
• /
• 2012

The rifling design problem has continuous-type shape variables and an integral number of riflings. In addition, it requires considerable time for analysis because its behavior should be described by a nonlinear finite element model (FEM). Therefore, this study presents an efficient design process for rifling based on a design of experiment (DOE) approach. First, Bose's orthogonal array is used to represent 25 runs for four design variables including three shape variables and one integer variable. Then, nonlinear FE analyses are performed. Next, to minimize the bullet resistance without affecting the bullet velocity and bullet rotational angle immediately before a bullet leaves the gun barrel, a what-if design is performed. In the proposed what-if design, a functional including the design objective and constraints is constructed and effect analysis is performed by using the functional. It is found that the new design obtained from the what-if design shows better results than the current one.