• 콘크리트학회논문집
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• 제15권2호
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• pp.297-304
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• 2003

본 연구에서는 철근콘크리트 기둥과 철골보로 구성된 혼합 골조구조의 접합부에 대한 구조적 특성을 평가하였다. 주요변수로는 본 연구에서 제안한 자주식(子株式) 횡보강근 상세와 기존의 RCS 공법에서 사용되고 있는 ㄱ-4조각 조합형 및 용접형 등의 횡보강근 상세를 대상으로 하였다. 실험체는 총 5개의 내부접합부를 대상으로 2/3 축소로 제작하여 접합부의 전단 및 내진성능을 평가하였다. 실험의 결과, 모든 실험체에서 최대내력 이후 강도 및 강성의 큰 저하없이 실험이 종료되었다. 따라서, 자주식(子株式) 횡보강근을 사용한 RCS 접합부의 구조성능은 4조각 조합형 및 용접형 등의 기존 공법과 동등 이상의 구조적 성능을 확보하는 것으로 나타나 외부 판넬의 전단기여도는 압축스트러트에 의해 평가하는 것이 보다 적절할 것으로 판단된다.

• Journal of Korean Neurosurgical Society
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• 제44권5호
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• pp.303-307
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• 2008

Objective: The authors reviewed clinical and radiological outcomes in patients with three column injury of the cervical spine who had undergone posterior cervical fixation using Nitinol shape memory alloy loop in the anterior-posterior combined approach. Materials: Nine patients were surgically treated with anterior cervical fusion using an iliac bone graft and dynamic plate-screw system, and the posterior cervical fixation using Nitinol shape memory loop ($Davydov^{TM}$) at the same time. A retrospective review was performed. Clinical outcomes were assessed using the Frankel grading method. We reviewed the radiological parameters such as bony fusion rate, height of iliac bone graft strut, graft subsidence, cervical lordotic angle, and instrument related complication. Results: Single-level fusion was performed in five patients, and two-level fusion in four. Solid bone fusion was presented in all cases after surgery. The mean height of graft strut was significantly decreased from $20.46{\pm}9.97mm$ at immediate postoperative state to $18.87{\pm}8.60mm$ at the final follow-up period (p<0.05). The mean cervical lordotic angle decreased from $13.83{\pm}11.84^{\circ}$ to $11.37{\pm}6.03^{\circ}$ at the immediate postoperative state but then, increased to $24.39{\pm}9.83^{\circ}$ at the final follow-up period (p<0.05). There were no instrument related complications. Conclusion: We suggest that the posterior cervical fixation using Nitinol shape memory alloy loop may be a simple and useful method, and be one of treatment options in anterior-posterior combined approach for the patients with the three column injury of the cervical spine.

• 한국세라믹학회지
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• 제36권9호
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• pp.954-964
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• 1999

The effect of fabrication variables and microstructures on the compressive strength of open cell alumina zirconia and silicon nitride ceramics fabricated by polymeric sponge method was investigated. Bulk density and compressive strength of open cell ceramics were mainly affected by coating characteristics of ceramic slurry on polymeric sponge that controlled a shape thickness and defect of the struts. Sintering temperature was optimized for enhancement of strut strength and compressive strength of open cell ceramics. Relative density and compressive strength behaviors were relatively well matched with the predicted values. Open cell ceramics of lower relative density below 0.1 prepared by first relatively well matched with the predicted values. Open cell ceramics of lower relative density below 0.1 prepared by first coating of ceramic slurry had thin triangular prismatic struts that were often broken or longitudinally cracked. With an application of second coating of slurry shape of struts was transformed into thickner cylindrical one and defects in struts were healed but the relative density increased over 0.2 Open cell zirconia had both the highest bulk density and compressive strength and alumina had the lowest compressive strength while silicon nitrides showed relatively high compressive strength and the lowest density. Based upon the analysis open cell silicon nitride was expected to be one of potential structural ceramics with light weight.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 춘계학술대회 논문집
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• pp.2224-2229
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• 2008

High-Speed train has been developed and it becomes faster and environmental friendly. As trains run faster, Noise of trains is generated mainly by aerodynamic disturbance. Pantograph, both ends of trains, and gaps of coaches which are thought to be aerodynamic noise's factors are primarily studied. Pantograph is a similarly shaped metal framework on the roof of an electric high speed train, transmitting current from an overhead electric catenary wire. Panhead which contacts electric wires directly looks like a bluff strut, goes through flows, is sensitive to external disturbances and is one of the most important factors which decide whole vehicles' driving ability. In this study, aerodynamically robust optimized pantograph panhead shape is designed and then evaluated through subsonic wind tunnel test. To compare these with existing panhead rectangular shapes or circular cylinder shapes, By visualizing strong vortex flow patterns which are main noise sources, characteristics are compared and analyzed

• 대한조선학회지
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• 제27권4호
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• pp.15-26
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• 1990

본 연구는 표면 양력관 이론을 이용하여 초월 공동이 발생한 2차원 날개의 유동해석을 위한 제반 경계 조건을 검증하고 공동 뒷부분의 모형을 비교 검토한다. 해석해가 존재하는 2차원 대칭 스트럿 주위의 초월 공동 현상을 수치적으로 해석하여 그 결과를 해석해와 비교함으로써 표면 양력판 이론에 의한 프로펠러 공동 문제 해석의 가능성을 입증하였다. 특히, 공동 뒷부분의 비 선형 닫힘 모형, 타원형 닫힘 모형, 그리고 선형 닫힘 조건을 서로 비교 분석함으로써 공동 문제 해결에서 가장 중요한 공동 닫힘 조건의 영향을 보였다.

• 한국공간구조학회논문집
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• 제17권4호
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• pp.69-76
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• 2017

For evaluating equations of bursting force in different codes, comparative study of the formulas was conducted. Because the equations does not consider variables such as shape of anchorages, angle of tendons, and eccentricity, a relation between the bursting forces and the variables has to be analyzed. In this paper, therefore, a comparative analysis of bursting forces computed by equations in the codes and finite element analysis was performed. As a result, it could be figured out that bursting force equations in the local zone were determined by coefficient k.

• 한국콘크리트학회:학술대회논문집
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• 한국콘크리트학회 2003년도 봄 학술발표회 논문집
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• pp.451-456
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• 2003

The behavior of concrete deep beams in shear is substantially influenced by beam size and shape, loading conditions, reinforcement details, and material properties. Therefore, it is not easy to predict the ultimate response of beams correctly and take into account all those factors in practical shear design. In this study, a grid softened strut-tie model approach for determining the shear strengths of various reinforced concrete deep beams is proposed. The validity of the approach is examined through the strength analysis of numerous reinforced concrete deep beams tested to failure. The approach can be further developed to improve the current deep beam design procedures by incorporating the actual shear resisting mechanisms of deep beams.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2008년도 추계학술대회A
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• pp.138-143
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• 2008

Recently, a new periodic cellular metal(PCM) named as Wire wove Bulk Kagome(WBK) was introduced. Based on the shape of tetrahedra composing a WBK, WBKs are classified into two types, namely, concave and convex type. They are easily differentiated by changing the assembling sequence. The effect of geometrical parameters such as the wire diameter, strut length and number of layers on the compressive behavior of concave type WBK has already been investigated. In this work, the similar works were performed with the convex type WBKs. It was shown that the compressive strength of the convex type WBK was quite similar to that of the concave type. The compressive strengths of convex type specimens also depend on the slenderness ratio, but a little different from those of concave type specimens in the detailed behavior. And densification occurs earlier than the concave type WBK.

• 한국농공학회논문집
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• 제51권3호
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• pp.45-52
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• 2009

Generally, structures are analyzed as continuum. However, sometimes it is more efficient to analyze structure as a discrete model rather than as a continuum model in case of the structure has complex shape or loading condition. This study, therefore, suggests an improved analysis discrete model, named Equivalent Truss Model (further as "ETM"), which can obtain similar results with analyzing continuums analysis. ETM adopts a lattice truss to compose the members of the model, and analyses the structures. As a consequence, the ETM produced the identical outcome with the continuums analysis in section force of different structures and loading conditions. Similar results have been shown in internal stress analysis as well. Make use of that ETM is discrete, fractural path of beam was analyzed by ETM and the result was reasonable.

• 한국자동차공학회논문집
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• 제5권1호
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• pp.38-48
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• 1997

A method for performing kinematic design sensitivity analysis of vehicle suspension systems is presented. For modeling of vehicle suspensions, the multibody dynamic formulation is adopted, where suspensions are assumed as combination of rigid bodies and ideal frictionless joints. In a relative joint coordinate setting, kinematic constraint equations are obtained by imposing cut-joints that transform closed-loop shape suspension systems into open-loop systems. By directly differentiating the constraint equations with respect to kinematic design variables, such as length of bodies, notion axis, etc., sensitivity equations are derived. By solving the sensitivity equations, sensitivity of static design factors that can be used for design improvement, can be obtained. The validity and usefulness of the method are demonstrated through an example where kinematic sensitivity analysis of a MacPherson strut suspension of performed.