• Steel and Composite Structures
• /
• 제21권5호
• /
• pp.1031-1043
• /
• 2016

Optimization of the construction scheme of the cable-strut tensile structure based on error sensitivity analysis is studied in this paper. First, the element length was extracted as a fundamental variable, and the relationship between element length change and element internal force was established. By setting all pre-stresses in active cables to zero, the equation between the pre-stress deviation in the passive cables and the element length error was obtained to analyze and evaluate the error effects under different construction schemes. Afterwards, based on the probability statistics theory, the mathematical model of element length error is set up. The statistical features of the pre-stress deviation were achieved. Finally, a cable-strut tensile structure model with a diameter of 5.0 m was fabricated. The element length errors are simulated by adjusting the element length, and each member in one symmetrical unit was elongated by 3 mm to explore the error sensitivity of each type of element. The numerical analysis of error sensitivity was also carried out by the FEA model in ANSYS software, where the element length change was simulated by implementing appropriate temperature changes. The theoretical analysis and experimental results both indicated that different elements had different error sensitivities. Likewise, different construction schemes had different construction precisions, and the optimal construction scheme should be chosen for the real construction projects to achieve lower error effects, lower cost and greater convenience.

• 조명전기설비학회논문지
• /
• 제22권2호
• /
• pp.162-168
• /
• 2008

본 논문에서는 RCF 해석법을 싸이리스터 제어 FACTS 설비인 TCSC를 포함하는 전력계통의 미소신호안정도 해석에 적용하였다. 이산시스템에서 RCF 해석법에 기초한 고유치 감도해석 알고리즘을 제시하고 TCSC를 포함하는 전력계통에 적용하였다. 사례연구를 통해서 RCF 해석법이 TCSC의 주기적 스위칭 동작에 의해 발생하는 진동모드의 변화와 새로이 발생되는 불안정 진동모드의 정확한 해석에 매우 유용한 해석방법임을 보였다. 또한 RCF 해석법에 기초한 고유치 감도해석 방법을 사용하여 이산시스템에서 주기적 스위칭 동작에 의해 발생되는 중요 진동모드에 대한 제어기 감도계수를 정확히 구할 수 있음을 보였다. 이러한 사례연구 결과는 기존의 연속시스템에서의 상태방정식에 의한 해석결과와 크게 다른 것이며, RCF 해석법이 TCSC와 같이 주기적 스위칭 동작을 하는 설비를 포함하는 이산전력계통의 해석에 매우 유용한 방법임을 보여준다.

• 센서학회지
• /
• 제23권2호
• /
• pp.114-121
• /
• 2014

We report a polysilicon active area membrane field effect transistor (PSAFET) pressure sensor for low stress deflection of membrane. The PSAFET was produced in conventional FET semiconductor fabrication and backside wet etching. The PSAFET located at the front side measured pressure change using 300 nm thin-nitride membrane when a membrane was slightly strained by the small deflection of membrane shape from backside with any physical force. The PSAFET showed high sensitivity around threshold voltage, because threshold voltage variation was composed of fractional function form in sensitivity equation of current variation. When gate voltage was biased close to threshold voltage, a fractional function form had infinite value at $V_{tn}$, which increased the current variation of sensitivity. Threshold voltage effect was dominant right after the PSAFET was turned on. Narrow transistor channel established by small current flow was choked because electron could barely cross drain-source electrodes. When gate voltage was far from threshold voltage, threshold voltage effect converged to zero in fractional form of threshold voltage variations and drain current change was mostly determined by mobility changes. As the PSAFET fabrication was compatible with a polysilicon FET in CMOS fabrication, it could be adapted in low pressure sensor and bio molecular sensor.

• Nuclear Engineering and Technology
• /
• 제18권2호
• /
• pp.78-84
• /
• 1986

일차섭동이론을 이용하여 물질밀도 감도 계수의 표현식을 유도하였다. Super-Phenix I 평형노심의 초기상태를 기준계로 택했으며 유효중배계수를 계의 응답함수로 정의했다. 볼츠만 연산자의 구성요 소인 물질밀도로 표현되는 핵연료의 농축도와 실효밀도를 입력변화로 선정했다. 위 계산을 수행하는데 전산코드시스템 (KAERI-26군 단면적 library/1DX/2DB/PERT-V)가 사용되었다. 핵연료 농축도의 유효증배계수에 대한 감도계수는 4.576로 계산되었으며, 핵연료 실효밀도의 감도 계수는 0.0756으로 계산되었다. 본 연구는 감도해석법이 대형전산코드를 이용한 직접반복계산법에 비해 계산시간의 단축과 아울러 많은 정보를 준다는 것을 보여준다.

• 한국전산구조공학회논문집
• /
• 제23권5호
• /
• pp.535-541
• /
• 2010

본 연구에서는 정상상태의 비선형 열탄성 문제에 대하여 탄성 계수 및 열전도 계수에 대해서 보조변수법을 이용한 연속체 기반의 설계민감도 방정식을 유도하였고, 온도와 변위장이 연성된 보조방정식을 정의하여 효율적으로 설계민감도 해석을 수행하여 위상 최적설계에 적용하였다. 수치 예제를 통하여 열탄성 문제에서 위상 최적설계가 갖는 요소망 의존성을 살펴보았다. 또한 열 하중이 지배적인 경우와 기계적 하중이 지배적인 경우를 비교하여 다중 물리 연성문제에서 위상 최적설계가 갖는 하중에 대한 의존성을 고찰하였다.

• Architectural research
• /
• 제14권3호
• /
• pp.93-98
• /
• 2012

The objective of the study is to analyze the relative performance of factors affecting indoor air quality in multi-residential buildings in Korea. A study of the factors affecting indoor air quality is essential for establishing indoor air quality management strategies effectively. To observe the indoor air quality response following a modification of a given parameter, a sensitivity analysis was performed. The factors examined for the analysis include; wall/ceiling paper, adhesive for wall/ceiling paper, floor material, adhesive for floor material, and ventilation rate. The Experimental Design which identifies main effects among the design parameters with a few experiments was used to decrease the number of experiments. The simulation for indoor air quality was undertaken using a validated equation. Then, ANOVA(Analysis of Variance) was performed to evaluate the relative importance of each parameter affecting the indoor air quality. The result of the study indicates that the indoor air quality may be influenced most by adhesive for wall/ceiling paper, followed by ventilation rate and adhesive for floor material.

• 한국환경과학회지
• /
• 제27권12호
• /
• pp.1195-1203
• /
• 2018

Many consumers intend to make environmentally purchase. However, this is not always what occurs. A gap exists between consumer intentions to purchase environmentally friendly products and their actual purchase behavior. In this study, we examined the effect of situational factors such as price sensitivity, product quality perception, and label trust on the relationship between purchase intention and purchase behavior for environmentally friendly products. First, we conducted a theoretical consideration through a review of literature on price sensitivity, product quality perception, label trust, purchase intention and purchase behavior. Based on the literature review, we designed a structural model and developed the hypotheses. Next, we collected data using a survey and processed them statistically in order to verify the hypotheses. A total of 213 samples were collected and the data were analyzed using a structural equation model (LISREL 8.70). The results suggest that the situational factor of label trust has a moderating effect on the relationship between purchase intention and purchase behavior for environmentally friendly products. However, price sensitivity and product quality perception have no moderating effect. This means that trust in labels is important when consumers want to buy environmentally friendly products. Although this study has some limitations, it is expected that it will positively trigger follow-up research.

• Structural Monitoring and Maintenance
• /
• 제9권1호
• /
• pp.59-80
• /
• 2022

In the present study, the objective is to detect the structural damages using the responses obtained from the sensors at the optimal location under uncertainty conditions. Reducing the error rate in damage detection process due to responses' noise is an important goal in this study. In the proposed algorithm for optimal sensor placement, the noise of responses recorded from the sensors is initially reduced using the principal component analysis. Afterward, the optimal sensor placement is obtained by the damage detection equation based sensitivity analysis. The sensors are placed on degrees of freedom corresponding to the minimum error rate in structural damage detection through this procedure. The efficiency of the proposed method is studied on a truss bridge, a space dome, a double-layer grid as well as a three-story experimental frame structure and the results are compared. Moreover, the performance of the suggested method is compared with three other algorithms of Average Driving Point Residue (ADPR), Effective Independence (EI) method, and a mass weighting version of EI. In the examples, young's modulus, density, and cross-sectional areas of the elements are considered as uncertainty parameters. Ultimately, the results have demonstrated that the presented algorithm under uncertainty conditions represents a high accuracy to obtain the optimal sensor placement in the structures.

• 산업기술연구
• /
• 제17권
• /
• pp.261-275
• /
• 1997

The objective of this paper is to develop two numerical model for predicting the wave height with set-up/down near the surfzone on a arbitrary beach profile. Two wave models, regular wave model and random wave model, are based on the energy flux equation with the energy dissipation effects. The developed numerical models are verified by comparison of numerical results with analytical solutions that are derived under the simple conditions. The characteristics of parameters included in each model are then investigated and decided to the range of behaviour by the sensitivity analysis. For sensitivity analysis, we carried out total 46 laboratory tests. Finally, the developed numerical models are applied to the field where the wave height near the surfzone has been measured. From the applications of numerical models, it is concluded that the developed numerical models may accurately predict the wave height with the set-up/down near the surfzone on a arbitrary beach profile.

• 대한기계학회논문집B
• /
• 제27권12호
• /
• pp.1758-1765
• /
• 2003

Monte Carlo simulation(MC) method was used as an uncertainty assessment tool for gas flow measurement in this paper. Uncertainty sources for gas flow measurement were analyzed, and probability distribution characteristics of each source were discussed. Detailed MC methodology was described including the effect of the number of simulation. The uncertainty result was compared with that of the conventional sensitivity coefficient method, and it was revealed that the results were different from each other for this particular gas flow measurement case of which the modelling equation was nonlinear. The MC was comparatively simple, convenient and accurate as an uncertainty assessment method, especially in cases of complex, nonlinear measurement modelling equations. It was noted that the uncertainty assessment method should be selected carefully according to the mathematical characteristics of the measurement.