기능경사 소재 등가 물성치 예측을 위한 균질화 기법의 특성분석을 위한 수치해석

조진래,최주형,신대섭,Cho, Jin-Rae,Choi, Joo-Hyoung,Shin, Dae-Sub 한국전산구조공학회 2008 한국전산구조공학회논문집 Vol.21 No.1

기능경사 소재(FGM)에는 서로 다른 두 가지 구성입자들이 혼합되어 있는 경사층(graded layer)이 삽입되어, 소재 전 영역에 걸쳐 구성입자의 체적분율이 연속적이고 기능적으로 변화하도록 되어있다. 이러한 이상(dual-phase) 입자복합재의 열 기계적 거동을 해석함에 있어 필수적인 경사층의 물성치는 전통적으로 균질화 기법을 이용하여 예측되었다. 하지만, 이러한 균질화 기법은 구성입자의 형태, 분산구조 등과 같은 상세 형상을 반영하지 못하지 때문에 복합재의 총체적인 등가 물성치 예측에만 국한 되어왔다. 이러한 맥락에서 본 연구에서는 경사층을 미시역학적으로 이산화 모델링하고, 다양한 체적분율과 외부 하중조건에 대해 유한요소해석을 실시하여 이러한 균질화 기법들의 특성을 분석하였다. Graded layers in which two different constituent particles are mixed are inserted into functionally graded material such that the volume fractions of constituent particles vary continuously and functionally over the entire material domain. The material properties of this dual-phase graded region, which is essential for the numerical analysis of the thermo-mechanical behavior of FGM, have been predicted by traditional homogenization methods. But, these methods are limited to predict the global equivalent material properties of FGMs because the detailed geometry information such as the particel shape and the dispersion structure is not considered. In this context, this study intends to investigate the characteristics of these homogenization methods through the finite element analysis utilizing the discrete micromechanics models of the graded layer, for various volume fractions and external loading conditions.

유연핀을 적용한 2.5MW급 풍력발전기용 기어박스의 동응답 해석

조진래,정기용,Cho, Jin-Rae,Jeong, Ki-Yong 한국전산구조공학회 2016 한국전산구조공학회논문집 Vol.29 No.1

본 연구는 2.5MW급 풍력발전기용 기어박스의 동특성 분석에 관한 것으로서, 유연핀(flexible pin) 채용에 따른 유성기어축의 미스얼라인먼트(misalignment) 개선여부와 충격하중에 따른 기어박스의 동응답 특성을 유한요소해석을 통해 고찰하였다. 내부의 복잡한 기어시스템의 하중전달을 정확하게 그리고 효과적으로 반영하기 위해 치접촉을 등가 치강성계수를 갖는 스프링요소와 물림률을 이용하여 모델링하였다. 기어의 등가 치강성계수는 기어치에 대한 변형해석을 통해 계산하였으며, 동특성 분석을 위해 기어박스 입력단에 충격 토오크를 부과하였다. 수치실험을 통해 등가 치강성모델의 타당성을 검증하였으며, 양단 그리고 일단 고정축과의 상대 비교를 통해 유연핀 적용에 따른 유성기어축의 미스얼라인먼트 개선여부를 확인할 수 있었다. This study is concerned with the numerical investigation of dynamic characteristics of 2.5MW-class wind turbine gearbox in which the misalignment improvement of plenary gear shafts by the flexible pins and the dynamic impact response are analyzed by the finite element method. The tooth contact between gears is modelled using the line element having the equivalent tooth stiffness and the contact ratio to accurately and effectively reflect the load transmission in the internal complex gear system. The equivalent tooth stiffness is calculated by utilizing the tooth deformation analysis and the impulse torque is applied to the input shaft for the dynamics response characteristic analysis. Through the numerical experiments, the equivalent tooth stiffness model was validated and the misalignment improvement of planetary gear shafts was confirmed from the comparison with the cases of fixed shafts at one and both ends.

페트로프-갤러킨 자연요소법 : I. 개념

조진래,이홍우,Cho, Jin-Rae,Lee , Hong-Woo 한국전산구조공학회 2005 한국전산구조공학회논문집 Vol.18 No.2

본 논문에서는 수치적분 정도를 향상시킬 수 있는 새로운 무요소 기법을 제안한파 저자들에 의해 페트로프-갤러킨 자연요소법(PG-NEM)이라 명명된 이 새로운 기법은 보로노이 다이어그램과 델라우니 삼각화에 기반을 두고 있으며, 이는 BG-NEM이라 불리는 기존의 자연요소법과 개념적으로 동일하다. 하지만, 동일한 시험 형상함수와 시도 형상함수를 선택하는 BG-NEM과는 달리, PG-NEM에서는 지지영역이 적분을 위한 배경격자에 정확하게 일치하도록 시험 형상함수를 독립적으로 선택하는 페트로프-갤러킨 개념에 기반을 두고 있다. 따라서, 제안된 기법은 BG-NEM과 비교하여 수치적분 정도를 현저히 향상시킬 것으로 기대된다. In this paper, a new meshfree technique which improves the numerical integration accuracy is introduced. This new method called thc Petrov-Galerkin natural clement method(PG-NEM) by authors is based on the Voronoi diagram and the Delaunay triangulation which is based on the same concept used lot conventional natural clement method called the Bubnov-Galerkin natural element method(BG-NEM). But, unlike the BG-NEM, the test basis function is differently chosen, based on the concept of Petrov-Galerkin, such that its support coincides exactly with a regular integration region in background mesh. Therefore, it is expected that the proposed technique ensures the remarkably improved numerical integration accuracy in comparison with the BG-NEM.

Mobile harbor: structural dynamic response of RORI crane to wave-induced rolling excitation

조진래,Ki-Chul Han,Soon-Wook Hwang,Choon-Soo Cho,임오강 국제구조공학회 2012 Structural Engineering and Mechanics, An Int'l Jou Vol.43 No.5

A new concept sea-floating port called mobile harbor has been introduced, in order to resolve the limitation of current above-ground port facilities against the continuous growth of worldwide marine transportation. One of important subjects in the design of a mobile harbor is to secure the dynamic stability against wave-induced excitation, because a relatively large-scale heavy crane system installed at the top of mobile harbor should load/unload containers at sea under the sea state up to level 3. In this context, this paper addresses a two-step sequential analytical-numerical method for analyzing the structural dynamic response of the mobile harbor crane system to the wave-induced rolling excitation. The rigid ship motion of mobile harbor by wave is analytically solved, and the flexible dynamic response of the crane system by the rigid ship motion is analyzed by the finite element method. The hydrodynamic effect between sea water and mobile harbor is reflected by means of the added moment of inertia.

신경회로망을 활용한 타이어 크라운형상 최적설계

조진래,신성우,정현성,김남전,김기운,Cho, Jin-Rae,Shin, Sung-Woo,Jeong, Hyun-Sung,Kim, Nam-Jeon,Kim, Kee-Woon 대한기계학회 2002 大韓機械學會論文集A Vol.26 No.10

Contacting with ground in the post-card area size only, tire supports entire automobile weight. As well, it characterizes most of automobile running performance. Among the design parameters, the carcass contour becomes a key design factor. This paper deals with the time-effective optimal design of tire crown contour in order to improve the tire wear performance by employing a back-propagation neural network model.

탄소나노튜브가 보강된 기능경사 복합재: 자연요소법을 이용한 균열진전 수치해석

조진래(Jin-Rae Cho) 대한기계학회 2023 대한기계학회 춘추학술대회 Vol.2023 No.6

『나팔상사』와 성격묘사의 낙관성

조진래 ( Gene Lay Cho ) 근대영미소설학회 1995 근대 영미소설 Vol.2 No.1

Hardy`s primary interest is, as always, with his characters, and his sympathies are with them as people rather than with their time in history as the subject or setting of the novel. He argues that the writer`s problem is how to strike the balance between the uncommon and the ordinary so as on the one hand to give interest and on the other to give reality. In solving the problem, he thinks, human nature must never be made abnormal, the uncommonness should be in the events, not in the characters. This paper aims at examining the grammar of Hardy`s novel-writing in The Trumpet-Major, putting emphasis on analyzing its characters` states of mind and behaviors. The object to analyze those is to look Into how Hardy intends to avoid the tone and atmosphere of the proceding tragic novel, The Return of the Native. In Hardy criticism, one should be mindful of avoiding the categorization of him as a pessimistic and fatalistic novelist for the purpose of exploring his tragic aspects of novels. In spite of a little lack of inner conflict and many episodic narrations, the originality of The Trumpet-MaJor lies in the fact that it is basically optimistic in the view of its major and minor characters.

탄소나노튜브가 기능경사적으로 보강된 복합재 평판의 대변형 수치 해석

조진래(Jin-Rae Cho) 대한기계학회 2022 대한기계학회 춘추학술대회 Vol.2022 No.6

격막(baffle)을 갖는 액체 저장탱크의 과도응답 해석

조진래(Jin-Rae Cho),이상영(Sang-Young Lee) 한국항공우주학회 2001 韓國航空宇宙學會誌 Vol.29 No.4

밝고 명랑한 전원 공동체: 하디의 『푸른 숲 나무 아래』연구

조진래 ( Gene Lay Cho ) 근대영미소설학회 1999 근대 영미소설 Vol.6 No.2

Hardy`s Under the Greenwood Tree has often been called a prose pastoral and loved rather intensely if not the most highly-regarded of his novels. The protagonists, Dick and Fancy, in the environment of rural reality are not innocent of the facts of life. But it is the happiest of his works, it has no shade of tragedy and raises no serious issues. In most cases, the critical vlewpoints have regarded the centural theme of his idyllic novels as a clash between urban and rural values and modes of life; the latter is inevitably defeated Under the Greenwood Tree, however, does not belong to that category. This paper attempts to study its theme and characters as distinctive features, putting emphasis on the preservation of the rural community and its tradition. The Mellstock rustics, humorous, sympathetic, and tolerate, have the sentiment proper to the lovely peaceful life remote from the urbane huddle. Their composure and flexibility keep the Mellstock community from undergoing rapid and violent changes Rev. Maybold as the alien lover and Fancy as the returning native do not come into conflicts with Dick, the native lover. The old ways, though they will not prevail in the future, can be brought into harmony with the new through the marriage of Fancy and Dick. And the Mellstock community remains as it has been.