• Journal of the Korean Data and Information Science Society
• /
• 제15권2호
• /
• pp.331-337
• /
• 2004

In the analysis of massive volume data, a neural network model is a useful tool. To implement the Neural network model, it is important to select initial value. Since the initial values are generally used as random value in the neural network, the convergent performance and the prediction rate of model are not stable. To overcome the drawback a possible method use samples randomly selected from the whole data set. That is, coefficients estimated by logistic regression based on the samples are the initial values.

• 한국자동차공학회논문집
• /
• 제1권2호
• /
• pp.42-48
• /
• 1993

In this paper, dynamic collapse behavior of the rectangular tube under impact loading is anlayzed using nonlinear finite element method of shell element. In case of shell element formulation using corotational element coordinates system, dynamic collapse behavior is analyzed without initial imperfection, and with initial imperfection. This paper reveals that the collapse of a rectangular tue without initial imperfection is caused by an error of transformation of the corotational coordinates system.

• Nonlinear Functional Analysis and Applications
• /
• 제26권5호
• /
• pp.1035-1044
• /
• 2021

Existence and uniqueness results for solutions of system of Riemann-Liouville (R-L) fractional differential equations with initial time difference are obtained. Monotone technique is developed to obtain existence and uniqueness of solutions of system of R-L fractional differential equations with initial time difference.

• 충청수학회지
• /
• 제35권2호
• /
• pp.137-147
• /
• 2022

In this paper, we considered the Dirichlet initial boundary value problem of a nonlinear viscoelastic wave equation with nonlinear damping and source terms, and investigated finite time blow-up phenomena of the solutions to the equation with arbitrary positive initial data, under suitable conditions.

• Journal of the Korean Society for Industrial and Applied Mathematics
• /
• 제26권4호
• /
• pp.353-361
• /
• 2022

For an initial value problem, using a weighted average between two adjacent approximates, we propose a simple one-step method based on the Euler method. This method is useful for solving stiff initial value problem, even when the step size is not very small. Moreover, it can be seen that the proposed method with some selected weights results in improved approximation errors.

• 제어로봇시스템학회:학술대회논문집
• /
• 제어로봇시스템학회 2001년도 ICCAS
• /
• pp.61.2-61
• /
• 2001

The purpose of the initial alignment of a SDINS is to get a coordinate transformation matrix from the body frame to the navigation frame. The initial alignment is one of the most important processes in the navigation system since its error has a large influence on the navigation solution. In this paper, a real-time initial alignment algorithm for the SDINS is developed using the Kalman filter. The steady state error analysis is performed for the developed Kalman filter technique and the gyrocompass loop method. The performance of the developed alignment method is compared with the gyrocompass loop method through the real-time alignment experiments.

• 충청수학회지
• /
• 제35권1호
• /
• pp.53-67
• /
• 2022

Nonlinear system of initial value problems involving R-L fractional derivative is studied. Monotone iterative technique coupled with lower and upper solutions is developed for the problem. It is successfully applied to study qualitative properties of solutions of nonlinear system of initial value problem when the function on the right hand side is nondecreasing.

• Clinics in Shoulder and Elbow
• /
• 제8권2호
• /
• pp.148-153
• /
• 2005

초기 탈구에서 시행한 조기 안정화 술식이 재발성 탈구의 Bankart 복원술 보다 좋은 결과를 나타내었으며 이는 관절경상 관찰되어진 관절낭 인대의 이완이나 관절와 연의 마멸이 결과에 영향을 미칠 수 있을 것으로 추정되었다. 또한 초기 탈구에서 발생된 Bankart 병변이 술기상으로 보다 쉽게 복원될 수 있으며 치유도 잘 되어 재발율이 감소될 것으로 생각되었고, 조기 수술적 치료를 통해 정상적인 일상 생활 및 스포츠 활동이 가능하리라 생각되었다. 따라서 활동력이 왕성하고 운동을 좋아하는 젊은 층이나 운동 선수에서는 문헌상에서 보고되고 있는 초기 탈구 후의 높은 재발율을 고려하여 초기 탈구 발생시 조기 안정화 술식이 유용할 것으로 사료되었다. 그러나 초기 탈구시 조기 안정화 술식을 시행할 지에 대해서는 보다 엄격한 적응이 요할 것으로 생각된다.

• 한국전산구조공학회논문집
• /
• 제20권1호
• /
• pp.19-28
• /
• 2007

이산화 된 구조물의 위상최적화 과정은 균일하게 분포된 재료 밀도의 위상으로 표현되는 초기 설계영역을 시발점으로 한다. 최적화 과정 동안 구조물의 위상은 고정된 설계영역 내에 주어진 최적화 문제를 만족시키는 방향으로 변화하면서, 최종적으로 최적 위상의 재료 밀도 분포를 생산한다. Eschenauer et al.에 의해 제안되었던 설계영역 안에 구멍을 도입하는 개념은 원래 경계면의 최적화 문제에 대해 설계변수의 유한적인 변화를 촉진시켜 최적화의 수렴성 개선을 도모하기 위함이었으나, 위상최적화의 관점에서는 초기 위상의 정의에 따라 다양한 최적 위상이 생산되는 것을 의미한다. 본 연구에서는 초기 설계영역 안에 국소적인 솔리드 상을 도입해 초기 위상에 변화를 주었을 때, 한정된 재료 하에 구조물에 배치 가능한 다양한 최적 위상을 산출할 수 있음을 검증하였다. 수치 예제로서 초기 설계영역 내에 다양한 치수를 가지는 국부적인 원형 솔리드의 고정된 개수를 투입하여 간단한 MBB-보의 위상최적 설계를 수행하였다.

• 한국CDE학회논문집
• /
• 제10권4호
• /
• pp.244-253
• /
• 2005

In the initial ship design stage of shipyards, the hull form design, the basic design (compartment modeling and ship calculation), and the hull structural design are being performed by different systems. Thus, the problem on interfaces between these systems occurs. To solve this, we developed the hull form design system 'EzHULL' and the compartment modeling and ship calculation system 'EzCOM-PART' for developing finally an integrated ship design system. And, in this study, we present an object-oriented hull structural design .system 'EzSTRUCT', which is developed recently. A structural design in an initial design stage can be frequently changed, because the design is not firmly determined yet. Therefore, designers perform the simplified structural modeling with bigger structural parts (or objects) such as deck, longitudinal bulkhead, etc. in the initial design stage, and the detailed structural modeling with smaller structural parts such as plate, seam, slot, etc. in the detailed design stage. However, the existing hull structural CAD system used in a shipyard is not efficient in generating a 3D CAD model in the initial design stage, because it has difficulty in handling frequent changes in design. Therefore, designers initially draw 2D drawings in the initial design stage, and generate the 3D CAD model from these 2D drawings in the detailed design and production design stages. In this study, the hull structural design system, which can efficiently generate a 3D CAD model through rapid modeling at an initial design stage, was developed in this study To evaluate the applicability of the developed system, we applied it to hull structural modeling of various ships such as a VLCC, a bulk carrier, etc. As a result, it could efficiently generate a 3D CAD model of a hull structure.