• Steel and Composite Structures
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• 제25권6호
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• pp.727-734
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• 2017

This paper describes a quasi-static finite element analysis, which uses the explicit integration method, of the apex joint of a cold-formed steel portal frame. Such cold-formed steel joints are semi-rigid as a result of bolt-hole elongation. Furthermore, the channel-sections that are being connected have a reduced moment capacity as a result of a bimoment. In the finite element model described, the bolt-holes and bolt shanks are all physically modelled, with contact defined between them. The force-displacement curves obtained from the quasi-static analysis are shown to be similar to those of the experimental test results, both in terms of stiffness as well as failure load. It is demonstrated that quasi-static finite element analysis can be used to predict the behavior of cold-formed steel portal frame joints and overcome convergence issues experienced in static finite element analysis.

• Geomechanics and Engineering
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• 제17권2호
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• pp.207-214
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• 2019

Dams have a great importance on energy and irrigation. Dams must be evaluated statically and dynamically even after construction. For this purpose, Torul dam built between years 2000 and 2007 Harsit River in Gümüşhane province, Turkey, is selected as an application. The Torul dam has 137 m height and 322 GWh annual energy production capacity. Torul dam is a kind of concrete face rock fill dam (CFRD). In this study, static and pseudo seismic stability of Torul dam was investigated using finite element method. Torul dam model is constituted by numerical stress analysis named Phase2 which is based on finite element method. The dam was examined under 11 different water filling levels. Thirteenth stage of the numerical model is corresponding full reservoir condition which water filled up under crest line. Besides, pseudo static coefficients for dynamic condition applied to the dam in fourteenth stage of the model. Stability assessment of the Torul dam has been discussed according to the displacement throughout the dam body. For static and pseudo seismic cases, the displacements in the dam body have been compared. The total displacements of the dam according to its the empty state increase dramatically at the height of the water level of about 70 m and above. Compared to the pseudo-seismic analysis, the displacement of dam at the full reservoir condition is approximately two times as high as static analysis.

• 한국해양공학회지
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• 제9권2호
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• pp.53-60
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• 1995

A multi-leg spread mooring system for floating offshore structures is important, but the multi-leg static analysis is complicated due to the nonlinear behavior of each line and the effect of current which affects each line differently. The pretensioned position of the multi-leg mooring system obtained from the static equilibrium condition changes into a different position due to external loads and current. In this paper, the new position and the static tension at each line are caculated. The relation between the initial static equilibrium position and the new position due to the external loads is expressed in terms of the Taylor's series expansion. The Runge-Kutta $4^{th}$ method is employed in analyzing the 3-dimensional static cable nonlinear equations.

• Structural Engineering and Mechanics
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• 제4권5호
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• pp.497-511
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• 1996

The equivalent static force procedure and the response spectrum analysis method are widely used for seismic analyses of multi-story buildings. The equivalent static force procedure is one of the most simple but less accurate method in predicting possible seismic response of a structure. The response spectrum analysis method provides more accurate results while it takes much longer computational time. In the response spectrum method, dynamic response of a multi-story building is obtained by combining modal responses through a proper procedure such as SRSS or CQC method. Since all of the analysis results are expressed in absolute values, structural engineers have difficulties to combine them with the results obtained from the static analysis. Design automation is interrupted at this stage because of the difficulty in the decision of the most critical design load. Pseudo-dynamic analysis method proposed in this study provides more accurate seismic analysis results than those of the equivalent static force procedure since the dynamic characteristics of a structure is considered. And the proposed method has an advantage in combination of the analysis results due to gravity loads and seismic loads since the direction of the forces can be considered.

• 한국화재소방학회논문지
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• 제31권4호
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• pp.86-94
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• 2017

본 연구에서는 소방시설의 내진설계기준에 의한 Cook Book 방식과 Static System Analysis 방식을 비교 해석하였다. Cook Book 방식은 배관을 동일 구간마다 나누어 해석한다. 이 방식은 배관, 물 그리고 관부속의 무게에 따라 버팀대를 설계하는 방식으로 해석하는 구간 외에는 응력해석이 불가능하다. 그러나 Static System Analysis는 배관 전체를 하나의 구조체로 보기 때문에 전체 배관에 대한 응력해석이 가능하다. 국소적으로 발생되는 치명적 응력 값에 대해서는 국부적으로 배관의 응력을 해소할 수 있는 장치의 설치를 통해 적극적으로 배관해석을 할 필요가 있다. 국내의 경우 소방시설의 내진설계기준이 Cook Book 방식만을 제시하고 있어 내진설계의 다양화에 많은 문제점을 가지고 있다. 그러므로 공학적으로 검증된 여러 종류의 Static System Analysis 방법을 통해 배관의 내진 설계를 방법을 적용할 필요가 있다.

• 대한전기학회논문지:전기기기및에너지변환시스템부문B
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• 제55권5호
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• pp.245-249
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• 2006

This study tries to test and analyze the static friction torque generated by an electromagnetic clutch. Then the torque is improved by optimizing the shape of armature. For the purpose of design change and optimization of the electromagnetic clutch, the static friction torque prediction is very important. We construct an axi symmetric FEM model for analyzing the static friction torque and used a torque tester for evaluating the real torque. For a test, predicted static friction torque is compared with the experimental one to discuss the rationality of torque analysis process. The analytical result agrees well with experimental data, explaining the validity of the mathematical process and FEM model. After confirming the torque analysis process, the optimization process is investigated. The optimization result shows that the static torque is improved by changing the armature shape.

• 한국공작기계학회:학술대회논문집
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• 한국공작기계학회 2003년도 춘계학술대회 논문집
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• pp.494-499
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• 2003

This paper concerns the static, dynamic and thermal characteristics analysis of a high-speed spindle system for horizontal machining centers with 45mm x50,000rpm. The spindle system is designed based on the angular contact ceramic ball bearings, built-in motor, oil-air lubrication method and oil jacket cooling method. The structural and thermal analysis models of spindle system are constructed by the finite element method. The static and dynamic characteristics are estimated based on the static deformation, modal parameter, mode shape and frequency response function, and the thermal characteristics are estimated based on the temperature rise, temperature distribution and thermal deformation. The analysis results illustrate that the designed spindle system has excellent structural and thermal stabilities

• International Journal of Aeronautical and Space Sciences
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• 제2권2호
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• pp.82-94
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• 2001

The purpose of this paper is to analyze the static and dynamic stability-of the unmanned airship under development ; the target airship's over-all length of hull is 50m and the maximum diameter is 12.5m. For the analysis, the dynamic model of an airship was defined and both the nonlinear and linear dynamic equations of motion were derived. Two different configuration models (KA002Y and KA003Y) of the airship were used for the target model of the static stability analysis and the dynamic stability analysis. From the result of analyses, though the airship is unstable in static stability, dynamic characteristics of the airship can provide the stable dynamic stability. All of the results, airship models and dynamic flight equations will be an important basement and basic information for the next step of developing the automatic flight control system(AFCS) and the stability augmentation system(SAS) for the unmanned airship as well as for the stratospheric airship in the future.

• International Journal of Control, Automation, and Systems
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• 제3권1호
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• pp.56-69
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• 2005

In this paper, it is clearly shown that the two well-known necessary and sufficient conditions mp n as generic static output feedback pole-assignment and mp + d(m+p) n+d as generic minimum d-th order dynamic output feedback pole-assignment on complex field, unbelievably, do not match up each other in strictly proper linear systems. For the analysis, a diagram analysis is newly created (which is defined by the analysis of 'convoluted rectangular/dot diagrams' constructed via node-branch conversion of the signal flow graphs of output feedback gain loops). Under this diagram analysis, it is proved that the minimum d-th order dynamic output feedback compensator for pole-assignment in m-input, p-output, n-th order systems is quantitatively decomposed into static output feedback compensator and its associated d number of arbitrary 1st order dynamic elements in augmented (m+d)-input, (p+d)-output, (n+d)-th order systems. Total configuration of the mismatched data is presented in a Table.

• 정보보호학회논문지
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• 제30권6호
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• pp.1131-1139
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• 2020

소스코드에 대한 정적 분석은 광범위한 소스코드에 대해서 잔존하는 보안약점을 찾는 것으로 정적 분석 도구를 활용하여 점검을 하고, 그 결과에 대해서 정적 분석 전문가가 정탐 및 오탐 분석을 한다. 이 과정에서 분석양이 많고 오탐의 비율이 높아 많은 시간과 노력이 들어가게 되어 효율적으로 분석하는 방안이 요구되고 있다. 또한 전문가들은 정·오탐 분석을 할 때 결함이 발생한 라인의 소스코드만 보고 분석을 하는 경우는 드물다. 결함의 유형에 따라서 주변의 소스코드를 같이 분석하고 최종 분석 결과를 내리게 된다. 이러한 정적 분석 도구를 사용하여 전문가가 정·오탐을 판별하는 어려움을 해결하기 위해서 본 논문에서는 정적 분석 도구가 찾은 보안약점이 정탐인지 아닌지를 전문가가 아닌 인공지능을 통해 판별하는 방법을 제안한다. 또한 이러한 기계학습에 사용되는 학습 데이터(결함주변 소스코드)의 크기가 성능에 어떤 영향을 미치는지 실험을 통해 최적의 크기를 확인하였다. 이 결과를 통해 정적 분석 후 정·오탐을 분류하는 정적 분석 전문가의 업무에 도움을 줄 것으로 기대한다.