• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2001년도 봄 학술발표회 논문집
• /
• pp.125-130
• /
• 2001

A existing design method of PSC girder bridges, according to total service loads, stress required tendon force at a time. Because this design method increases beam depth, design of long span is difficult. However, As UC girder stressing at difficult loading stages reduces sectional depth of PSC girder, both design and operation of long span bridges is possible. so, this study analyzes the effect of design parameter (Girder Strength, Girder Spacing, Span Length, Joint Strength) on the beam depth of IPC girder continuous bridges, and shows sectional depth of UC girder for design of long span bridges. According to analysis, when a continuous bridges of same length span is at strength of joint over strength of girder of 600kg/$cm^{2}$, a change of beam depth is observed and when a continuous bridges of different span length is at strength of joint below strength of girder of 600kg/$cm^{2}$, a change of beam depth is observed. In two case, a change of beam depth is mostly observed over strength of girder of 350kg/$cm^{2}$ according to analysis of deflection data, a continuous bridges of IPC girder is nearly satisfied.

• 한국건축시공학회:학술대회논문집
• /
• 한국건축시공학회 2016년도 추계 학술논문 발표대회
• /
• pp.128-129
• /
• 2016

This study is to categorize the loading of multiple persons on a vertical building elements into three types to test the size of crowd pressure under each loading patterns. The loading patterns is divided under the combination of loading method and loading persons. The loading method is categorized into the method of instantaneous loading of hand on a force plate and the method of continuous loading. The loading persons has been composed of 1~5 persons under the loading patterns. The loading patterns is also divided into lateral loading, longitudinal loading, and agglomeration loading. The subject group has been composed of 12 males in 20s. The load measurement device(size 1800×600×36mm, capacity 20kN, rigidity 28kN/cm) has been designed and manufactured directly. To eliminate the difference of individual, the size of crowd pressure has been converted into the strength to weight ratio (maximum load/weight) for computation. The strength to weight ratio in lateral loading was about 0.91 under instantaneous loading and about 0.47 under continuous loading. The strength to weight ratio in longitudinal loading was about 0.65 under instantaneous loading and about 0.36 under continuous loading. The strength to weight ratio in agglomeration loading was about 0.65 under instantaneous loading and about 0.36 under continuous loading.

• Computers and Concrete
• /
• 제14권2호
• /
• pp.145-161
• /
• 2014

The article presents the statistical method of grouping the results of the compressive strength of concrete in continuous production. It describes the method of dividing the series of compressive strength results into batches of statistically stable strength parameters at specific time intervals, based on the standardized concept of "concrete family". The article presents the examples of calculations made for two series of concrete strength results, from which sets of decreased strength parameters were separated. When assessing the quality of concrete elements and concrete road surfaces, the principal issue is the control of the compressive strength parameters of concrete. Large quantities of concrete mix manufactured in a continuous way should be subject to continuous control. Standardized approach to assessing the concrete strength proves to be insufficient because it does not allow for the detection of subsets of the decreased strength results, which in turn makes it impossible to make adjustments to the concrete manufacturing process and to identify particular product or area on site with decreased concrete strength. In this article two independent methods of grouping the test results of concrete with statistically stable strength parameters were proposed, involving verification of statistical hypothesis based on statistical tests: Student's t-test and Mann - Whitney - U test.

• Structural Engineering and Mechanics
• /
• 제49권3호
• /
• pp.373-393
• /
• 2014

A finite element model for predicting the entire nonlinear behavior of reinforced high-strength concrete continuous beams is described. The model is based on the moment-curvature relations pre-generated through section analysis, and is formulated utilizing the Timoshenko beam theory. The validity of the model is verified with experimental results of a series of continuous high-strength concrete beam specimens. Some important aspects of behavior of the beams having different tensile reinforcement ratios are evaluated. In addition, a parametric study is carried out on continuous high-strength concrete beams with practical dimensions to examine the effect of tensile reinforcement on the degree of moment redistribution. The analysis shows that the tensile reinforcement in continuous high-strength concrete beams affects significantly the member behavior, namely, the flexural cracking stiffness, flexural ductility, neutral axis depth and redistribution of moments. It is also found that the relation between the tensile reinforcement ratios at critical negative and positive moment regions has great influence on the moment redistribution, while the importance of this factor is neglected in various codes.

• 한국소음진동공학회:학술대회논문집
• /
• 한국소음진동공학회 2006년도 춘계학술대회논문집
• /
• pp.66-72
• /
• 2006

Marine diesel engine production and refinements sought a continuous increase on mean effective pressure and thermal efficiency. These results in increased maximum combustion pressure within the cylinder and vibratory torque in crankshaft. As such, crankshaft should be designed and compacted within its fatigue strength. In this paper, the 8H25/33P($3,155ps{\times}900rpm$) engine for ship propulsion was selected as a case study, and tile strength analysis of its crankshaft is carried out by. simplified method recommended by IACS M53 and a detailed method with the crankshaft assumed as a continuous beam and bearing supported in its flexibility. The results of these two methods are compared with each other.

• 선박안전
• /
• 통권21호
• /
• pp.4-14
• /
• 2006

Marine diesel engine production and refinements sought a continuous increase on mean effective pressure and thermal efficiency. These results in increased maximum combustion pressure within the cylinder and vibratory torque in crankshaft. As such, crankshaft should be designed and compacted within its fatigue strength. In this paper, the 8H25/33P(3,155ps 900rpm) engine for ship propulsion was selected as a case study, and the strength analysis of its crankshaft is carried out by: simplified method recommended by IACS M53 and a detailed method with the crankshaft assumed as a continuous beam and bearing supported in its flexibility. The results of these two methods are compared with each other.

• Steel and Composite Structures
• /
• 제12권1호
• /
• pp.73-92
• /
• 2012

The effect of element interaction and material nonlinearity on the ultimate capacity of stainless steel plated cross-sections is investigated in this paper. The focus of the research lies in cross-sections failing by local buckling; member instabilities, distortional buckling and interactions thereof with local buckling are not considered. The cross-sections investigated include rectangular hollow sections (RHS), I sections and parallel flange channels (PFC). Based on previous finite element investigations of structural stainless steel stub columns, parametric studies were conducted and the ultimate capacity of the aforementioned cross-sections with a range of element slendernesses and aspect ratios has been obtained. Various design methods, including the effective width approach, the direct strength method (DSM), the continuous strength method (CSM) and a design method based on regression analysis, which accounts for element interaction, were assessed on the basis of the numerical results, and the relative merits and weaknesses of each design approach have been highlighted. Element interaction has been shown to be significant for slender cross-sections, whilst the behaviour of stocky cross-sections is more strongly influenced by the material strain-hardening characteristics. A modification to the continuous strength method has been proposed to allow for the effect of element interaction, which leads to more reliable ultimate capacity predictions. Comparisons with available test data have also been made to demonstrate the enhanced accuracy of the proposed method and its suitability for the treatment of local buckling in stainless steel cross-sections.

• 열처리공학회지
• /
• 제25권6호
• /
• pp.292-298
• /
• 2012

In this study, Cu-2.5at.%Ni-1at.%Si alloys were fabricated by horizontal continuous casting system to improve the electrical conductivity and mechanical properties of Cu-Ni-Si alloy. Withdrawing speed was changed with 50, 100, 150 and 200 mm/min for the optimum manufacturing condition. Microstructure was observed using OM, FE-SEM and TEM. Electrical conductivity was measured by 4-point probe method and mechanical properties were tested. A horizontal continuous cast thin slab had sound macro and micro structures with partly crystallized structures. Electrical resistivity decreased with increasing annealing temperature from 250 to $850^{\circ}C$, with increasing annealing temperature The maximum hardness and tensile strength were Hv 130, 610 MPa at $550^{\circ}C$, respectively. With changing withdrawing speed from 50 to 150 mm/min, hardness, tensile strength, yield strength and elongation were Hv 60-65, 210-230 MPa, 65-75 MPa and 40-50%, respectively.

• 재활치료과학
• /
• 제3권2호
• /
• pp.71-81
• /
• 2014

목적: 본 연구의 목적은 CPM (Continuous Passive Motion)을 뇌졸중 환자의 손 기능 및 수부 근력 재활에 사용하고 그 영향을 살펴보는데 있다. 연구방법 : 본 연구의 대상자는 뇌졸중으로 인한 편마비 증상을 가진, Brunnstrom 4-6단계에 해당하는 치료후 18개월 이내의 급성기 환자 3명이다 연구방법은 3명의 대상자에 대하여 단일사례 (A-B) 실험설계를 사용하였으며 CPM의 영향을 검사하기 위해 젭슨수지기능, 퍼듀페그보드, 수부근력 세 가지를 측정하였다. CPM 적용기간은 3주였으며, 적용회수는 하루 2회, 매회 20분씩, 총 30회기였다. 연구결과: 수부근력 측정 중 손끝잡기에서 대상자 2명의 값이 변화가 없었다. 그 외의 젭슨수지기능, 퍼듀페그보드, 수부근력 검사에서는 CPM 적용 후의 검사 결과가 향상되었다. 결과의 유효성 검증을 위하여 비모수적 통계방법인 Wilcoxon signed ranks test를 실시한 결과 모든 항목에 대한 P-Value가 0. 05 보다 큰 값이 나와 처치 전 후 값의 차이가 통계적으로는 유의미하지 않다는 결과를 얻었다. 결론: 참여 대상자 수가 적고 프로그램 적용 기간이 짧은 제한점이 있으나, 수부 재활을 위해 실시한 CPM이 연구대상자 전원의 손 기능 및 근력 향상에 영향을 주었다는 것을 확인하였다. 이는 주로 하지 기능과 근력 향상을 위해 사용되는 CPM이 급성기 뇌졸중 환자의 수부 치료에도 유용하게 사용될 수 있음을 보여준다.

• 한국콘크리트학회:학술대회논문집
• /
• 한국콘크리트학회 2006년도 추계 학술발표회 논문집
• /
• pp.117-120
• /
• 2006

This study is for the strengthening method of continuous bridge through external tendon strengthening that is the most general and effective among concrete bridge's strengthening method. Recently, it is numerous that slab's parts between spans have continuity for improving trafficable ability. However, in this case, slab would have a crack; bridge's durability would be damaged, and also it is too difficult to manage and maintain bridge due to the tensile strength of negative moment. Therefore, the purpose of this study is to demonstrate load-carrying through experiments and develop new external pre-stressing strengthening method for reinforcing continuous bridge.