p-Version 비선형 유한요소모텔에 의한 2방향 철근 콘크리트 슬래브의 역학적 거동해석

조진구,박진환,Cho, Jin-Goo,Park, Jin-Hwan 한국농공학회 2005 한국농공학회논문집 Vol.47 No.4

This study is focused on modeling to predict the behavior of two-way RC slabs. A new finite element model will be presented to analyze the nonlinear behavior of RC slabs. The numerical approach is based on the p-version degenerate shell element including theory of anisotropic laminated composites, theory of materially and geometrically nonlinear plates. In the nonlinear formulation of this model, the total Lagrangian formulation is adopted with large deflections and moderate rotations being accounted for in the sense of von Karman hypothesis. The material model is based on the Kuper's yield criterion, hardening rule, and crushing condition. The validity of the proposed p-version nonlinear RC finite element model is demonstrated through the load-deflection curves and the ultimate loads. It is shown that the proposed model is able to adequately predict the deflection and ultimate load of two-way slabs with respect to steel arrangements and steel ratios.

地盤과 構造物사이의 相互作用을 考慮한 農業用 사이로의 解析에 관한 硏究(Ⅰ) - 第 1 報 模型 및 프로그램의 開發 -

조진구,조현영,Cho, Jin-Goo,Cho, Hyun-Young 한국농공학회 1985 한국농공학회논문집 Vol.27 No.2

The reinforced concrete farm silos on the elastic foundatin are widely used in agricultural engineering because of their superior structural performance, economy and attractive appearance. Various methods for the analysis and design of farm silo, such as the analytical method, the finite difference method, and the finite element methods, can be used. But the analytical procedure can not be applied for the intricate conditions in practice. Therefore lately the finite element method has been become in the structural mechanics. In this paper, a method of finite element analysis for the cylindrical farm silo on ffness matrix for the elastic foundation governed by winkler's assumption. A complete computer programs have been developed in this paper can be applicable not only to the shell structures on elastic foundation but also to the arbitrary three dimensional structures. Assuming the small deflection theory, the membrane and plate bending behaviours of flat plate element can be assumed mutually uncoupled. In this case, the element has 5 degrees of freedom per node when defined in the local coordinate system. However, when the element properties are transformed to the global coordinates for assembly, the 6th degree of freedom should be considered. A problem arises in this procedure the resultant stiffness in the 6th degree of freedom at this node will be zero. But this singularity of the stiffness matrix can be eliminated easily by merely replacing the zero diagonal by dummy stiffness.

p-Version 비선형 유한요소 모델에 의한 철근 콘크리트 경사 슬래브의 역학적 거동 해석

조진구,박진환,Cho, Jin-Goo,Park, Jin-Hwan 한국농공학회 2005 한국농공학회논문집 Vol.47 No.5

The objectives of this study are to determine the behavior of simply supported skew RC slabs subjected to a point load. The p-version nonlinear skew RC FE model has been used. Integrals of Legendre polynomials are used for shape functions with p-level varying from 1 to 10. In the nonlinear formulation of this model, the material model is based on the Kupfer's yield criterion, hardening rule, and crushing condition and layered model is used through the thickness. The cracking behavior is modeled by a smeared crack model and the fixed crack approach is adopted as the crack model. It is shown that the proposed model is able to adequately predict the deflection and ultimate load of nonlinear skew RC slabs with respect to steel arrangements and steel ratios.

부분분포하중이 평면 포물선아치의 동적응답에 마치는 영향

조진구,박근수,Cho, Jin-Goo,Park, Keun-Soo 한국농공학회 2004 한국농공학회논문집 Vol.46 No.6

This study aims to investigate the effects of partially distributed loads on the dynamic behaviour of steel parabolic arches by using the elasto-plastic finite element model based on the Von Mises yield criteria and the Prandtl-Reuss How rule. For this purpose, the vertical and the radial load conditions were considered as a distributed loading and the loading range is varied from 40% to 100% of arch span. Normal arch and arch with initial deflection were studied. The initial deflection of arch was assumed by the sinusoidal motile of ${\omega}_i\;=\;{\\omega}_O$ sin ($n{\pi}x/L$). Several numerical examples were tested considering symmetric initial deflection when the maximum initial deflection at the apex is fixed as L/1000. The analysis resluts showed that the maximum deflection at the apex of arch was occurred when 70% of arch span was loaded. The maximum deflection at the quarter point of arch span was occurred when 50% of arch span was loaded. It is known that the optimal rise to span ratio between 0.2 and 0.3 when the vertical or radial distributed load is applied. It is verified that the influence of initial deflection of radial load case is more serious than that of vertical load case.

탄소섬유보강 플라스틱시트로 외부보강된 RC 슬래브의 p-Version 비선형 유한요소 해석

조진구,박진환,Cho, Jin-Goo,Park, Jin-Hwan 한국농공학회 2006 한국농공학회논문집 Vol.48 No.1

The p-version nonlinear finite element model has been developed to analyze the nonlinear behavior of simply supported RC slabs strengthened with carbon fiber reinforced plastic sheets. The shape function is adopted with integral of Legendre polynomials. The compression model of concrete is based on the Kupfer's yield criterion, hardening rule, and crushing condition. The cracking behavior is modeled by a smeared crack model. In this study, the fixed crack approach is adopted as being geometrically fixed in direction once generated. Each steel layer has a uniaxial behavior resisting only the axial force in the bar direction. Identical behavior is assumed fur tension and compression of steel according to the elastic modulus. The carbon fiber reinforced plastic sheets are considered as reinforced layers of equivalent thickness with uniaxial strength and rigidity properties in the present model. It is shown that the proposed model is able to adequately predicte the displacement and ultimate load of nonlinear simply supported RC slabs by a patch with respect to reinforcement ratio, thickness and angles of CFRP sheets.

초기 처짐을 갖는 평면 포물선 아치의 동적 거동

조진구,박근수,Cho , Jin-Goo,Park, Keun-Soo 한국농공학회 2004 한국농공학회논문집 Vol.46 No.2

This study aims to investigate the dynamic behaviour of a parabolic arch with initial deflection by using the elasto-plastic finite element model where the von-Mises yield criteria have been adopted. The initial deflection of arch was assumed by the high order polynomial of ${\omega}_i$ = ${\omega}_o$${(1-{(2x/L)}^m)}^n$) and the sinusoidal profile of ${\omega}_i$ = ${\omega}_o$$\sin$(n$\pi$x/L). Several numerical examples were tested considering symmetric initial deflection modes when the maximum initial deflection of an arch is fixed as L/500, L/1000, L/2000 or L/5000. The effects of polynomials order on the dynamic behavior of arch were not conspicuous. The most unfavorite dynamic response occurs when the maximum initial deflection varies from L/1000 to L/4000 if the initial deflection mode is represented by high order polynomials.

Pre-stress를 도입(導入)한 Steel Beam에 관(關)한 실험적(實驗的) 연구(硏究)

조진구 ( Jin Goo Cho ),박병기 ( Byung Kee Park ) 한국농공학회 1975 韓國農工學會誌 : 전원과 자원 Vol.17 No.4

This research was carried out to investigate several mechanical characteristics of pre-stressed steel beams. The configuration of specimens used for this study were as follows; a cover plate having permissible fiber stress of 4,000 kg/㎠ was welded at bottom having the allowable bending stress 2500 kg/㎠ steel beam, the section ratios of pre-stressed steel beam and cover plate were 0.5 and 0.6. Adopted pre-stresses were 0%, 50%, and 100% of an allowable fiber stress of a steel beam. The results obtained from the study may be summarized as follows; 1. The elastic range of a beam was increased by the application of pre-stress to the beam, which leads to a lighter section. 2. The permissible moment capacity of a pre-stressed steel beam was greated than that of a steel beam without pre-stressing. 3. The equivalent allowable stress induced by adopting the different section ratio of pre-stressed beam to cover plate were figured out 4. The optimum value of section ratio of beam and cover plate was 0.3 to 0.4 in case of a 1.5m span composite beam, a combination of an allowable stress 2,500kg/㎠ steel beam and a permissible fiber stress 4,000 kg/㎠ steel cover plate, was used. 5. The magnitude of the pre-stress was desirable to be same as the allowable stress of a steel beam. 6. It was concluded that if the construction techniques in the field are developed and improved, the practicing of pre-stress to the steel structure has a promising future.

탄성비잔상에 놓인 철근콘크리트 축대칭 쉘의 정적 및 동적 해석(III) - 비선형 정적 거동을 중심으로 -

조진구 ( Cho Jin Goo ) 한국농공학회 1997 韓國農工學會誌 : 전원과 자원 Vol.39 No.3

In all inelastic deformations time rate effects are always present to some degree. Whether or not their exclusion has a significant influence on the prediction of the material behaviour depends upon several factors. In the study of structural components under static loading conditions at normal temperature it is accepted that time rate effects are generally not important. However metals, especially under high temperatures, exhibit simultaneously the phenomena of creep and viscoplasticity. In this study, elastoplastic and elasto-viscoplastic models include nonlinear geometrical effects were developed and several numerical examples are also included to verify the computer programming work developed here in this work. Comparisons of the calculated results, for the elasto-viscoplastic analysis of an internally pressurised thick cylinder under plane strain condition, have shown that the model yields excellent results. The results obtained from the numerical examples for an elasto-viscoplastic analysis of the Nuclear Reinforced Concrete Containment Structure(NRCCS) subjected to an incrementally applied internal pressure were summarized as follows: 1. The steady state hoop stress distribution along the shell layer of dome and domewall junction part of NRCCS were linearly behave and the stress in interior surfaces was larger than that in exterior. 2. However in the upper part of the wall of NRCCS the steady state hoop stress increased linearly from its inner to outer surfaces, being the exact reverse to the previous case of dome/dome-wall junction part. 3. At the lower part of wall of NRCCS, the linear change of steady state hoop stress along its wall layer began to disturb above a certain level of load increase.

등분포(等分布) 하중(荷重)을 받는 4변고정(邊固定)인 철근(鐵筋)콘크리트 사판(斜板)의 해석(解析)(II) -제(第)2보(報) 변장비(變長比)의 영향(影響)-

조진구 ( Cho Jin Goo ),이원준 ( Lee Won Joon ) 한국농공학회 1986 韓國農工學會誌 : 전원과 자원 Vol.28 No.1

In this paper, the characteristics of mechanical behaviour due to various edge-ratio of uniformly loaded clamped skew-plates has been described. In this study, the skew-plate was discretized using 8-noded isoparametric element and Mindlin's plate theory was adapted in finite element formulation. The edge-ratio 0.5, 0.8, 1.0, 1.2, 1.5, 2.0 and 2.5 were considered. Hence, five cond-itions of the skew-angle, the seven levels of edge ratio were tried. When the edge-ratio was 2.5 or the edge-ratio was 2.0 and the skew-angle was less than 45 degree, the behaviour of the uniformly loaded the skew-plate with all edges clamped was independent of the skew-angle.

전두환 대통령의 일본 공식 방문을 둘러싼 외교교섭

조진구(Jin-Goo Cho) 한일민족문제학회 2023 한일민족문제연구 Vol.45 No.-

This paper examines Korea-Japan relations around the time of President Chun Doo Hwan’s official visit to Japan, which was realized in September 1984, about 20 years after the two countries established diplomatic relations, based on Korean diplomatic documents. In the diplomatic negotiations between Korea and Japan over the agenda to be addressed at the summit or the joint statement to be announced as a result, the areas of interest and meaning given to both sides were different. On the economic front, Korea requested Japan to expand the Generalized System of Preferences(GSP), ease non-tariff barriers, dispatch an import promotion team to Korea, and transfer industrial technology to resolve the imbalance in trade with Japan, but Japan responded passively. There seemed to be little awareness that historical issues could have a negative impact on building a future-oriented relationship between the two countries. In particular, the legal status and treatment of the Korean residents in Japan, and the issues of confirming the legal status of third-generation Korean residents in Japan and younger and the abolition of fingerprinting for Koreans in Japan were only resolved in the early 1990s. President Chun Doo Hwan’s visit to Japan can be said to be the starting point for a new Korea-Japan relationship in that it improved the Japanese people’s image of South Korea and served as an opportunity to broaden the interest and exchanges between the two people of both countries toward each other. However, there were many challenges to overcome. この論文は、韓日両国が国交を樹立して約20年経った1984年9月に実 現した全斗煥大統領の日本公式訪問を前後した時期の韓日関係を韓国 外交文書を手がかりに考察したものである。首脳会談で取り上げるア ジェンダや結果として発表する共同声明をめぐる韓日間の外交交渉過 程を見ると両側の関心分野や意味付与が異なっていたことがわかる。 経済面で韓国側は対日貿易不均衡の解消のために一般特恵関税(GSP) の拡大と非関税障壁の緩和、対韓輸入促進団の派遣、産業技術の移転 などを日本に要請したが、日本は消極的な対応で一貫した。歴史問題 が未来志向の両国関係の構築に悪影響を及ぼす可能性があるという意 識も弱かったように思われる。特に、「特殊な歴史的背景」がある在日 韓国人の法的地位や処遇問題は日本の強い抵抗に遭い、在日韓国人3歳 以下の法的地位確定問題や在日韓国人の指紋押捺の撤廃問題の解決は 1990年代初頭まで待たなければならなかった。 全斗煥大統領の日本訪問は韓国に対する日本国民のイメージを改善 し、相手に対する両国国民の関心と交流の幅を広げるきっかけになっ たという点では新しい韓日関係の出発点であったかもしれない。しか し、乗り越えなければならない課題は山積していた。