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.

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.

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.

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.

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.

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.

국교정상화 40주년의 한일관계 : 신한일어업협정과 독도문제를 중심으로

조진구(Cho Jin Goo) 고려대학교 평화연구소 2006 평화연구 Vol.14 No.1

동아시아에서의 중일 간의 새로운 파워 게임

趙眞九(Cho, Jin-goo) 국방부 군사편찬연구소 2010 군사 Vol.- No.77

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.

국제국가 일본의 국제적 역할 모색 연구 : 1980년대와 1990년대를 중심으로

조진구(Cho, Jin-Goo) 한일민족문제학회 2020 한일민족문제연구 Vol.39 No.-

戦後の日本外交は新たな国際秩序の創出のための理念と構想が欠けてい たとの批判を受けてきた。この研究では、戦後最初の理念主導の外交と評され た1977年8月の福田ドクトリンの背景と内容を踏まえて、1980年代と1990年代を 研究対象にして日本が国際社会でいかなる役割を果たそうとしたのかを歴史的 文脈のなかで考察してみた。 1977年8月に発表された福田ドクトリン以降、日本は経済中心の東南アジア 外交から脱してアジア太平洋地域へと関心領域を広げていった。また、アジア で唯一にG7首脳会議に参加するようになるまで国際的地位が向上された日本 は経済問題のみならず安全保障問題まで積極的に取り組んでいった。日本外 交のグローバル化と冷戦の終結という国際環境の変化の中で日本は、PKO協 力法を制定して自衛隊を国連平和維持活動(PKO)に参加させるようになった。 これを機に日本外交安保の中核というべき日米同盟も変貌し、｢国際貢献｣とい う名の下で自衛隊の活動領域も拡大され、日本の防衛政策や防衛力にも大き な変化が見られるようになった。 これらの変化は、日本が単なる経済大国ではなくグローバルな行為者として 積極的なリーダーシップを発揮して経済以外に政治軍事的側面で国際社会か らの期待や日本自ら自覚した責任と役割とも関連がある。これは、1980年代と1990年代に欧米とともに3極を形成するほど経済的存在感が大きくなったのを背 景に推し進められた日本の｢大国志向｣外交がよく表れていた。そこには一定の 成果とともに限界があり、21世紀における日本外交の課題として残されていたと 言うこともできる。 Post-war Japanese diplomacy has been criticized for its lack of ideology and initiative to create a new international order. In this paper, I looked at the role of Japan in the international community in a historical context, during the 1980s and 1990s, based on the background and contents of the Fukuda Doctrine in August 1977, which was called the first post-war ideological-led diplomacy, After the Fukuda Doctrine in August 1977, Japan was moving away from economic-oriented Southeast Asian diplomacy and expanding its areas of interest to the Asia-Pacific region. Japan, an international country whose status has grown enough to participate in the G7/G8 Summit, is the only one in Asia, and it expanded the field of interest to security issues. The US-Japan alliance, which is the core of Japan’s diplomacy and security policy, was transformed by the enactment of the PKO Cooperation Act and the participation of the Self-Defense Forces in UN peacekeeping operations amid the globalization of Japanese diplomacy and the end of the Cold War. Under the name of the international contribution, the Self-Defense Forces’ field of action has also expanded, and Japan’s defense policy and defense capabilities have also undergone significant changes. These were related to the expectations of the international community and Japan’s self-aware responsibility and role in terms of political and military in addition to the economy, as Japan showed active leadership as a global actor rather than a simple economic power. This can be said to be a good example of Japan’s “big country-oriented” diplomacy unfolded against the backdrop of the growing economic presence that formed a triad with the United States and Europe in the 1980s and 1990s. There were limitations with certain achievements, and it was left as a task of Japanese diplomacy in the 21st century.