• 대한조선학회논문집
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• 제56권3호
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• pp.187-199
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• 2019

In the case of gas carriers and oil tankers, pipes are installed on the upper deck as a moving passage to load LPG, LNG, crude oil, etc. Pipes used for loading or unloading liquid cargo in cargo holds are connected to the hull through support structures. However, many cases of hull damage have been reported where the various equipment and support structures are installed on the upper deck. It is assumed that not only the structural discontinuity where the hull and the pipe support structure meet, but also action due to the pipe loads and the hull girder bending moment are simultaneously affected. This paper deals with the design and strength evaluation of the support structure of pipes and cables installed on the upper deck of commercial ships and offshore structures. For these supporting structures, design conditions and working loads were defined. The design procedure was established through the structure analysis on the method of determining the member dimensions. A series of finite element analysis was performed on the factors to be considered in the design and the effects were discussed. The accuracy and design periods of the strength evaluation was improved and reduced by application of the automation program in the finite element analysis. It is also expected that the design reliability of the shipyard is improved.

• EDISON SW 활용 경진대회 논문집
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• 제6회(2017년)
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• pp.204-215
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• 2017

비공기압 타이어(Non-Pneumatic Tire)는 공기압 타이어(Pneumatic Tire)와는 다르게 스포크(Spoke)를 이용하여 공기압을 대체하는 타이어이다. 비공기압 타이어는 기존 공기압 타이어가 가지고 있는 펑크 발생이 없고, 공기압을 유지할 필요도 없다. 또한, 온도가 급격하게 변하는 우주에서도 사용이 가능하다. 이런 점에서 비공기압 타이어는 차세대 바퀴로써 주목 받고 있다. 하중이 가해지는 Honeycomb구조를 Edison을 이용하여 유한요소 해석을 진행하고, 각각의 결과를 비교하여 최적의 허니콤 구조를 찾았다.

• 한국해양공학회지
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• 제34권5호
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• pp.316-324
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• 2020

This paper presents comparative studies of reliability analysis and meta-modeling using the sampling method of Monte Carlo simulation for the structure design of an automatic ocean salt collector (AOSC). The thickness sizing variables of structure members are considered as random variables. Probabilistic performance functions are selected from strength performances evaluated via the finite element analysis of an AOSC. The sampling methods used in the comparative studies are simple random sampling and Sobol sequences with varied numbers of sampling. Approximation methods such as the Kriging model is applied to the meta-model generation. Reliability performances such as the probability failure and distribution are compared based on the variation of the sampling method of Monte Carlo simulation. The meta-modeling accuracy is evaluated for the Kriging model generated from the Monte Carlo simulation and Sobol sequence results. It is discovered that the Sobol sequence method is applicable to not only to the reliability analysis for the structural design of marine equipment such as the AOSC, but also to Kriging meta-modeling owing to its high numerical efficiency.

• 한국지능시스템학회논문지
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• 제18권1호
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• pp.122-126
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• 2008

상용화된 FEM 코드와 3차원 솔리드 모델러를 통합하여 3차원 균열에 대한 자동 응력확대계수 해석 시스템을 개발하였다. 하나 또는 몇 개의 3차원 균열을 포함하는 기하학적 모델을 정의한다. 시스템에 저장된 몇 개의 절점패턴을 선택하면 자동적으로 퍼지지식 처리기법을 이용한 기하학적 모델 전 영역에 절점들이 중첩되어진다. 절점들은 생성되어지고 데로우니삼각화 법에 의한 사면체 솔리드요소가 생성되어진다. 최종적으로 완전한 유한요소 모델이 생성되어져 응력해석을 수행하게 된다. 본 논문은 몇몇 함수들을 실현시키기 위한 방법론에 대해 묘사하고 있으며 시스템의 타당성을 제시하였다.

• Journal of Computational Design and Engineering
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• 제1권2호
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• pp.88-95
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• 2014

Because the cost of performance testing using actual products is expensive, manufacturers use lower-cost computer-aided design simulations for this function. In this paper, we propose using hexahedral meshes, which are more accurate than tetrahedral meshes, for finite element analysis. We propose automatic hexahedral mesh generation with sharp features to precisely represent the corresponding features of a target shape. Our hexahedral mesh is generated using a voxel-based algorithm. In our previous works, we fit the surface of the voxels to the target surface using Laplacian energy minimization. We used normal vectors in the fitting to preserve sharp features. However, this method could not represent concave sharp features precisely. In this proposal, we improve our previous Laplacian energy minimization by adding a term that depends on multi-normal vectors instead of using normal vectors. Furthermore, we accentuate a convex/concave surface subset to represent concave sharp features.

• 한국CDE학회논문집
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• 제8권1호
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• pp.10-18
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• 2003

FEM (Finite Element Method) is a fundamental numerical analysis technique in wide spread use in engineering application. As the solving time occupies small portion of entire FEM analysis time because of development of hardware, the relative lime to the whole analysis time to make mesh mod-els is growing. In particular, in the case of stiffeners such as features attached to plate in ship structure, the line constraints are imposed on mesh model together with other constraints such as holes. To auto-matically generate two dimensional quadrilateral mesh with the line constraints, an algorithm is pro-posed based on the constrained Delaunay triangulation and Q-Morph algorithm in which the line constraints are not considered. The performance of the proposed algorithm is evaluated. And some numerical results of our proposed algorithm ate presented.

• 한국정밀공학회:학술대회논문집
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• 한국정밀공학회 2004년도 추계학술대회 논문집
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• pp.1154-1159
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• 2004

Unexpected postoperative changes, such as growth in rib hump, has been occasionally reported after corrective surgery for scoliosis. However there has been experimental data for explanation of these changes, nor the suggestion of optimal correction method. This numerical study was designed to investigate the main correlating elements in operative kinematics with post-operative changes of vertebral rotation and rib cage deformation in the corrective surgery of scoliosis. To develop a scoliotic spine model automatically, a special program for converting normal spine model to scoliotic spine model was developed. A mathematical finite element model of normal spine including rib cage, sternum, both clavicles, and pelvis was developed with anatomical details. The skeletal deformity of scoliosis was reconstructed, by mapping the X-ray images of a scoliosis into this three dimensional normal spine and rib cage model. The geometric mapping was performed by translating and rotating the spinal colume with the amount analyzed from the digitized 12 built-in coordinate axes in each vertebral image. By utilizing this program, problems generated in mapping procedure such as facet joint overlapping, vertebral body deformity could be automatically resolved.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2007년도 춘계학술대회A
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• pp.538-543
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• 2007

A procedure is proposed to generate optimal grid with minimal user intervention while keeping a prescribed level of accuracy, using an adaptive X-FEM and applied to shape optimization. In spite of various advantages of X-FEM, however, there are several obstacles for practical applications. Because of using a uniform background mesh and additional degree of freedoms for enrichment, an X-FEM is usually computationally more expensive than traditional finite element method. Furthermore, there are often accuracy problems. For an automatic procedure of optimal mesh generation, an h-adaptive scheme and a posteriori error estimation obtained by a post-processing process are utilized. The procedure is shown by 2-D shape optimization examples.

• 대한전기학회:학술대회논문집
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• 대한전기학회 1989년도 하계종합학술대회 논문집
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• pp.432-435
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• 1989

This paper presents an algorithm for electric field analysis which is essential to insulation design of extra-high voltage oil-filled cable accessories using finite element method. Governing equation is induced by electromagnetic equation. Variational method is adopted for FEN formulation. Automatic mesh generation which saves time and labor is introduced for the input data. The application results of proposed algorithms were used for insulation design to develop 345kV cable joint.

• 한국전산구조공학회:학술대회논문집
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• 한국전산구조공학회 2006년도 정기 학술대회 논문집
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• pp.341-346
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• 2006

This paper provides the resuIts on the evaluation of dynamic characteristics of the optimized shells. Five fundamental technologies such as computer-aided geometric design, automatic mesh generation, shell finite element, design sensitivity analysis and shell optimization process, are used for shell optimization maximizing the fundamental natural frequency. A dome shell is adopted for the shell shape optimization and the dynamic characteristic of the optimized shell such as the variation of natural frequencies is then investigated. From the investigation, more constraint functions related to shell natural frequencies is necessarily required to effectively control dynamic characteristics of the optimized shells.