• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.34 no.4
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• pp.83-88
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• 2006

One of the most important works in the development of military aircraft is to construct and utilize the various technical data and information needed in the design, analysis and evaluation under integrated system structure. A vast and various data in oder to optimize cockpit design is needed in geometric & arrangement design, vision analysis and escape system design. In addition, the application of ergonomics cockpit design concept based on the sorts of human elements and anthropometric data as design consideration for pilots is required. To accomplish above these activities, the data gathered and formed through the aircraft development program was become database and developed by tool to be able to support ergonomics cockpit design work.

• 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.

• Journal of the KSME
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• v.29 no.3
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• pp.279-293
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• 1989

CAD/CAM 시스템에서 유한요소해석에 필요한 과정들과 이와 관련된 기술 및 연구 동향을 살펴 보았다. 근래에 이르러 CAD/CAM 시스템의 개념이 초기의 자동제도 시스템에 그치지 않고, 이제는 제품의 설계 개발에서부터 제조에 이르는 일련의 엔지니어링 작업을 통합하는 CAE(Computer Aided Engineering) 시스템의 개념으로 발전되고 있으며, 우리나라에서도 이 분야에 많은 관심과 수요가 크게 늘고 있음은 당연한 추세라 할 수 있다. 그러나 아직까지 이에 필요한 소프트웨어들이 국내에서 개발되지 않아 전량 수입에 의존하고 있는 실정으로, 앞으로 이러한 수입추세는 점점 늘어날 것으로 전망된다. 더욱이 최근 들어 선진국들이 원천 프로그 램(source code)의 이전을 기피함에 따라 관련기술의 국산화가 어렵고, 이들의 응용에 제약이 많아 기술의 예속화가 우려된다 하겠다. 따라서 현재 국내의 산어 규모와 기술 수준으로 미루 어볼 때, 국내에서도 소프트웨어들을 개발해야 할 시점에 와 있다고 하겠다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.31 no.1 s.256
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• pp.105-112
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• 2007

The linkage framework of geometric modeling based on NURBS(Non-Uniform Rational B-Spline) surface and shell finite analysis is developed in the present study. For this purpose, geometrically exact shell finite element is implemented. NURBS technology is employed to obtain the exact geometric quantities for the analysis. Especially, because NURBS is the most powerful and wide-spread method to represent general surfaces in the field of computer graphics and CAD(Computer Aided Design) industry, the direct computation of surface geometric quantities from the NURBS surface equation without approximation shows great potential for the integration between geometrically exact shell finite element and geometric modeling in the CAD systems. Some numerical examples are given to verify the performance and accuracy of the developed linkage framework. In additions, trimmed surfaces with some cutouts are considered for more practical applications.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2012.05a
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• pp.46-51
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• 2012

This study aims to develop the performance analysis program on the staged combustion cycle of the liquid rocket engine using liquid oxygen(LOx) as oxidizer, liquid hydrogen(LH2) and RP-1 as fuel. The developed analysis program can obtain the propellant mass flow rate, the specific impulse, and representative design values of engine components for the required thrust satisfying pressure, mass flow, and energy balance conditions. The analysis results show that the the specific impulses (Isp) compared to those of the real engines have been less than 1%. With additional constraints, the program will be improved for the system optimization.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.27 no.5
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• pp.724-733
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• 2003

Fatigue design rules for welds in the ASME Boiler and Pressure Vessels Code are based on the use of Fatigue Strength Reduction Factors(FSRF) against a code specified fatigue design curve generated from smooth base metal specimens without the presence of welds. Similarly, stress intensification factors that are used in the ASME B3l.1 Piping Code are based on component S-N curves with a reference fatigue strength based on straight pipe girth welds. But the determination of either the FSRF or stress intensification factor requires extensive fatigue testing to take into account the stress concentration effects associated with various types of component geometry, weld configuration and loading conditions. As the fatigue behavior of welded joints is being better understood, it has been generally accepted that the difference in fatigue lives from one type of weld to another is dominated by the difference in stress concentration. However, general finite element procedures are currently not available for effective determination of such stress concentration effects. In this paper, a mesh-insensitive structural stress method is used to re-evaluate the S-N test data, and then more effective method is proposed for pressure vessel and piping fatigue design.

• The Journal of the Institute of Internet, Broadcasting and Communication
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• v.23 no.2
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• pp.163-168
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• 2023

In this paper, a novel platform for chemical sensing and biosensing is presented. The working principle is based on the coupling efficiency and interference properties of optical directional coupler (DC) and multimode interference coupler (MMIC). It has been realized using planar technology to allow integration on a silicon substrate. Firstly, the dispersion curves of DC and MMIC is described, and the design specification of an optimized slot optical waveguide to increase waveguide sensitivity is selected. Next, the sensor response to the refractive index change of sensing analyte is numerically simulated. The numerical results reveal that high effective index change per refractive index unit (RIU) change of analyte is obtained, and the sensitivity can be tuned using the DC and MMIC design technique.

• Journal of Korea Society of Industrial Information Systems
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• v.21 no.2
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• pp.1-10
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• 2016

In this paper, we consider the algorithms and numerical analysis for real-time integrated control system and resource management of large-scale manufacturing smart factory system. There various data transmitted on Cyber-Physical-System (CPS) is necessary to control in real time, as well as the terminal and the platform with respective system service. This will be a true smart manufacturing which consisting of existing research results, and a numerical analysis by the parameter-specific information. In this paper, Jacoby calculation to reflect the optimization algorithms that are newly proposed. It also presents a behavior that optimal operational algorithm on CPS which is adapted to the sensing data. In addition, we also verify the excellence of the real-time integrated control system through experimentation, by comparison with the existing research results.

• Proceedings of the Korea Water Resources Association Conference
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• 2022.05a
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• pp.355-355
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• 2022

기후변화에 의한 이상가뭄 발생 등을 대비하기 위한 비상용수 또는 대체수자원으로서의 지하수 개발수요가 증가하는 추세에 따라 기저유량 확보 및 수질 개선 방안을 수립하는 것은 지속가능한 수자원 이용·관리 측면에 있어서 매우 중요하다. 지하수 및 기저유량 확보 및 수질 개선을 위해서는 지표-지하수 통합 관리가 필요하며 이를 기반으로 지하수 및 기저유량 변동에 대한 인과관계 파악 및 구체적인 조사가 필요하다. 따라서 본 연구에서는 지표-지하수에 대한 계절적·시공간적 변동성을 잘 모의할 수 있는 통합 모델을 기반으로 지하수위 변동을 포함한 물수지 분석과 장·단기 유출해석이 정량적으로 분석하고자 하였으며, 평창군 대화면, 만대지구, 신둔천 유역을 대상으로 간벌, BMP, LID를 비롯한 다양한 시나리오에 따른 기저유량 및 수질변화 그리고 오염특성 파악을 수행하였다. 본 연구에서는 지표-지하수 통합 모델링을 위하여 SWAT-MODFLOW 모형을 활용하였으며, 간벌 시나리오의 경우 모형 Source code를 수정하여 간벌의 효과를 모의할 수 있도록 수정하였다. 또한 BMP와 LID의 경우 각 HRU별로 저감시설에 대한 효율 및 매개변수 조정을 통해 효율을 모의하였다. 모형의 입력자료 구축을 위하여 지표 모형의 경우 DEM, 토지이용도, 토양도를 활용하였으며, 지하수 모형의 경우 지하수기초조사자료에 수록된 수리전도도, 비산출율, 비보유율 조사결과를 활용하여 입력자료를 구축하였다. 그 결과 간벌시나리오의 경우 건기시 최소 6.7% 이상의 하천유량, 22.56% 이상의 기저유량, 그리고 0.3 m 이상의 지하수위 확보가 가능한 것으로 나타났다. BMP의 경우 유역면적의 약 7%에 BMP가 설치된 것으로 나타났으며, 이에 따른 하천 말단 SS저감효율은 6.7%로 나타났으나 유량에서는 큰 차이를 나타내지 못하였다. 마지막으로 LID시나리오의 경우 적용 소유역의 강우시 평균유량이 약 29% 감소하였으며 건기시 평균 기저유량이 약 44%이상, 평균 BFI는 약 0.13 증가한 것으로 나타났다.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.41 no.8
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• pp.791-797
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• 2017

Today, we are using computer simulations in various engineering disciplines to reduce the time and cost of product development. The scope of simulations is increasingly complex and diverse for different fields such as mechanical, electrical, thermal, and fluid. Thus, it is necessary to use integrated simulations. In order to overcome these problems, a language has been developed to effectively describe and implement simulations is Modelica. To model and simulate a system, physical models can be broadly divided into causal and acausal models. The most important feature of Modelica is acausal programming. In this study, we will introduce simple concepts and explain about the usage of Modelica. Furthermore, we will explain the vibration analysis of a two degree-of-freedom system and the design of appropriate parameters by using Modelica.