• Journal of the Society of Naval Architects of Korea
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• v.28 no.1
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• pp.69-82
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• 1991

The dynamic stability of the long vertical beam subjected to the periodic axial load is investigated. As a solution method, the Galerkin's method is used to obtain a set of coupled Mathieu type equations. To obtain the stability chart, both the perturbation method and numerical method are used, and the results of the both methods are compared with each other. The stability regions for the various boundary conditions are obtained, Also the effects of the viscous damping, the mean tension and the multi-frequency parametric excitation are studied in detail.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.6
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• pp.564-571
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• 2007

In the present study, stern form optimization has been carried out using computational fluid dynamics (CFD) techniques. The viscous pressure drag has been minimized to optimize stern shape. Parametric modification function has been used to modify the shape of the hull. By the use of the parametric modification function and algebraic scheme to grid manipulation, the initial ship geometry was easily deformed according to change of design parameters. For purpose of illustration, KRISO 319K VLCC (KVLCC) is chosen for example ship to demonstrate stern form optimization. The numerical results indicate that the optimized hull yields a reduction in viscous resistance.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2011.04a
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• pp.18-21
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• 2011

비정형의 대공간 구조물은 대량의 부재가 규칙성을 가지고 공간상에서 반복되는 패턴을 가지는 특징이 있다. 이러한 특징은 기존의 구조해석 모델러로부터의 접근을 어렵게 하는 반면, 관계성과 규칙성을 논리적으로 모델링함으로써 최종 모델을 생성해내는 파라메트릭 모델링 방법에는 매우 적합하다. 본 연구에서는 이전의 연구를 통해 개발된 파라메트릭 구조해석 모델링 툴인 STRAUTO을 이용해 전형적인 비정형 대공간 구조물인 용인시민체육공원 주경기장의 모델링에 파라메트릭 모델링 기법을 직접 적용해 봄으로써 이 새로운 접근법의 적합성과 효율성을 검토해 보았다.

• Transactions of Materials Processing
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• v.9 no.2
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• pp.140-151
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• 2000

The finite element mesh approach for tool surface description is applied effectively to analyze sheet metal stamping processes. To improve the mesh quality and the stability of the mesh generation process, a gybrid method based on the grid approach and the Delaunay triangulation is proposed in the present work. In the present study, a general method for the mathematical description of arbitrarily shaped tool surface is proposed by introducing the parametric surface approach. A polynomial function employed to describe the base parametric surface and the boundary curves are defined to describe arbitrary three-dimensional trimmed surfaces. To verify the validity of the proposed method, automatic mesh generation is carried out for some shosen complicated parts including actual automotive panel.

• Journal of Ocean Engineering and Technology
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• v.13 no.2 s.32
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• pp.176-185
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• 1999

Currently, large size shipyards have performed the generating of piece and the nesting using shipbuilding-oriented CAD program, which requires high skilled operator and costs a lot. So, medium and small size shipyards have pursued other way to obtain the generating and the nesting due to an economic and a technical problems. Therefore, this research is to develop a program for the generating of pieces with parametric macro method and a STRIP program for the nesting of pieces by PC.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.5 no.3
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• pp.43-50
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• 2006

In this successive study, the analytical realization of coupled system was introduced using the times series identification and spectrum analysis, which was compared with conventional FFT spectrum. Also, the numerical responses of second order system, which is coupled, were solved using the numerical calculation of Runge-Kutta Gill method. After numerical analysis, the displacement, velocity and acceleration were acquired. Among them, the response of displacement was used for the analysis of time series spectrum. Among several time series, the ARMAX algorithm was proved to be appropriate for the spectrum analysis of the coupled system. Using the separated response of 1st and 2nd mode, the mode was calculated separately. And the responses of mixed modes were also analyzed for calculation of the mixed modes in the coupled system.

• Journal of the Korean Society of Manufacturing Process Engineers
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• v.5 no.3
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• pp.36-42
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• 2006

The analytical realization of uncoupled system was introduced in this study using times series and its spectrum analysis. The ARMAX spectra of time series methods were compared with the conventional FFT spectrum. Also, the response of second order system uncoupled was solved using the Runge-Kutta Gill method. In this numerical analysis, the displacement, velocity and acceleration were calculated. The displacement response among them was used for the power spectrum analysis. The ARMAX algorithm in time series was proved to be appropriate for the mode estimation and spectrum analysis. Using the separate response of first and second mode, each modes were calculated separately and the response of mixed modes was also analyzed for the mode estimation using several time series methods.

• Proceedings of the KSME Conference
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• 2008.11b
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• pp.2043-2052
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• 2008

The increasing heat generation rates in CPU of notebook computers motivate a research on cooling technologies with low thermal resistance. This paper develops a closed-loop two-phase cooling system using a micropump to circulate a dielectric liquid(PF5060). The cooling system consists of an evaporator containing a boiling enhancement microstructure connected to a condenser with mini fans providing external forced convection. The cooling system is characterized by a parametric study which determines the effects of volume fill ratio of coolant, existence of a boiling enhancement microstructure and pump flow rates on thermal performance of the closed loop. Experimental data shows the optimal parametric values which can dissipate 33.9W with a film heater maintained at $95^{\circ}C$.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.22 no.52
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• pp.347-354
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• 1999

Statistical Process Control(SPC) which uses control charts is widely used to inspect and improve manufacturing process as a effective method. A parametric method is the most common in statistical process control. Shewhart chart was made under the assumption that measurements are independent and normal distribution. In practice, this assumption is often excluded, for example, in case of (equation omitted) chart, when the subgroup sample is small or correlation, it happens that measured data have bias or rejection of the normality test. A bootstrap method can be used in such a situation, which is calculated by resampling procedure without pre-distribution assumption. In this study, applying bootstrap percentile method to (equation omitted) chart, it is compared and evaluated standard process control limit with bootstrap percentile control limit. Also, under the normal and non-normal distributions, where parameter is 0.5, using computer simulation, it is compared standard parametric with bootstrap method which is used to decide process control limits in process quality.

• Proceedings of the Computational Structural Engineering Institute Conference
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• 2010.04a
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• pp.247-250
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• 2010

최근 많은 건축가들이 파라메트릭 디자인 도구에 관심을 가지고 형태에 대한 다양한 실험을 하고 있는 것과는 달리, 구조 엔지니어들은 이에 적절하게 대응하지 못하고 있다. 현재 파라메트릭 모델과 구조해석 프로그램사이의 자료교환을 가능하게 하는 인터페이스가 없는 것이 주된 원인이다. 따라서 구조 엔지니어들도 자유롭게 파라메트릭 방법론의 장점을 활용한 모델을 생성하고, 그것을 구조해석에 바로 사용할 수 있도록 하는 일이 오늘날 구조계가 당면한 과제이다. 본 연구에서는 파라메트릭 모델로부터 구조해석 모델을 자동으로 생성하는 인터페이스의 실무 적용가능성을 살펴보기 위하여, 파라메트릭 디자인 도구의 특성과 확장성을 검토하고, 라이노를 기반으로 하는 구조해석 모델 생성 플러그인을 개발하였다.