• 대한조선학회논문집
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• 제53권5호
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• pp.362-370
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• 2016

The weight estimation and calculation of FPSO topsides is first performed at the bidding stage of projects. At this time, it is difficult to estimate and calculate accurately the weight because most of items of FPSO are not apparently defined. Especially, in the case of the pipe rack module, its portion of the total weight and the range of weight variation are large due to special features of piping and electric equipment in the module. Thus, it is very important to estimate and calculate accurately its weight in the task of the weight estimation and calculation of FPSO topsides. In this study, the past data for the weight of the pipe rack module were collected and analyzed, the WBS (Work Breakdown Structure) for the pipe rack module was constructed, and primary variables and secondary variables for developing a weight estimation and calculation model were selected. That is, after analyzing the past data, the volume was selected as the primary variable and the regression analysis was performed based on the variable. Then, several secondary variables were selected and incorporated into a weight estimation and calculation model. At this time, the weight per discipline was assumed from ratios of the total weight. Finally, the weight of the pipe rack module was estimated and calculated by using the developed model. As a result, the deviation from the model was better than that (-20 % ~ 60 %) of other studies about the weight estimation and calculation of FPSO topsides. Thus, the validity and applicability of the weight estimation and calculation of the pipe rack could be checked.

• ETRI Journal
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• 제35권5호
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• pp.931-934
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• 2013

The weight calculation in an iterative algorithm is the most computationally costly task in computed tomography image reconstruction. In this letter, a fast algorithm to speed up the weight calculation is proposed. The classic square pixel rotation approximate calculation method for computing the weights in the iterative algorithm is first analyzed and then improved by replacing the square pixel model with a circular pixel model and the square rotation approximation with a segmentation method of a circular area. Software simulation and hardware implementation results show that our proposed scheme can not only improve the definition of the reconstructed image but also accelerate the reconstruction.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2000년도 추계학술대회논문집A
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• pp.357-362
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• 2000

Allowable stress design(ASD) method has been widely used to design steel structures such as boiler and heat recovery steam generator(HRSG) of power plant. However, many researchers are recently intrested in road and resistance factor design(LRFD) method which may take the place of ASD. In this work, the weight calculation of steel structure was compared when ASD and LRFD were applied respectively. For the calculation of weight of steel structure, computer program was developed and applied to obtain beam weight. Using this program and GTSTRUDL, structural design program, weight of steel structure is calculated. As a result of weight calculation, maximum 5.4% of weight reduction is achieved among examples of this study by applying LRFD comparing with the result of ASD, and those results quite dependent on the applied load and member classification.

• 디지털융복합연구
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• 제11권12호
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• pp.201-211
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• 2013

본 연구는 다양한 가중치 산출방법을 적용하여 각 차원별 가중치 및 고객만족도지수를 비교하고 시사점을 밝혀보고자 한다. 이를 위해 가중치 산출방법을 주관적 방법과 통계적 방법으로 구분하고, 다시 주관적 방법은 고정총합법, 그리고 통계적 방법은 상관분석, 회귀분석, 주성분분석, 요인분석, 구조방정식으로 세분화하였다. 연구결과 주관적 방법과 통계적 방법에 의한 가중치는 서로 차이가 있는 것으로 나타났고, 분석방법에 따른 가중치의 순위는 유사한 패턴으로 구분되었다. 그리고 가중치 산출방법에 따른 각 차원별 가중치는 큰 편차를 보여 차원간의 변별력 및 안정성에 차이를 나타냈다. 마지막으로 다양한 가중치 산출방법에 따른 고객만족도지수는 구조방정식, 회귀분석, 상관분석, 산술평균, 주성분분석, 고정총합법, 요인분석의 순으로 높게 나타났고, 각 방법론에 따른 고객만족도지수는 통계적으로 유의한 차이가 있는 것으로 나타났다.

• 대한조선학회논문집
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• 제53권2호
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• pp.154-161
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• 2016

There are several existing studies for the weight estimation of offshore plants. However, most of them were applicable at the pre-FEED (Front End Engineering Design) stage. In this paper, a preliminary study on a method for the weight estimation and calculation of offshore EPC (Engineering Procurement Construction) projects is made for the use at the estimation stage after FEED. Based on literature surveys including ISO (International Organization for Standardization) 19901-5 about weight estimation, we proposes new weight factors and a weight curve. Weight factors defined in this study include MTO (Material Take-Off), estimated weight, FEED maturity factor, allowance factor, and contingency factor. The proposed method utilizes bottom-up approach for weight estimation and it can be used for the weight estimation and calculation of offshore EPC projects at the estimation stage.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2020년도 봄 학술논문 발표대회
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• pp.157-158
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• 2020

In order to calculate construction costs properly, it is necessary to add the weight that reflects different worksite conditions. The implementation of the weight, however, is difficult because it is impossible to determine whether wight should be added in basic work or whether weight values are overlapped. Special worksite conditions further complicate the matter. Furthermore, overlapping implementation of weight values result in overestimation of construction costs. The current study clearly analyzed the weight value items in the current construction cost calculation standards, and analyzed the weight value items included under the basic productivity category to propose an improvement of weight standards. Basically, the estimating standards provide 140 weight value items, with different levels of weight given to each item. Among 1,333 items in the estimating standards, 140 include weight values. Some items have two types of weight values.

• Structural Engineering and Mechanics
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• 제74권4호
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• pp.533-545
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• 2020

An optimal design method for a spoke double-layer cable-net structure (SDLC) is proposed in this study. Simplified calculation models of the SDLC are put forward to reveal the static responses under vertical loads and wind loads. Next, based on an energy principle, the relationship among the initial prestress level, cross-sectional areas of the components, rise height, sag height, overall displacement, and relative deformation is proposed. Moreover, a calculation model of the Foshan Center SDLC is built and optimized. Given the limited loading cases, material properties of the components, and variation ranges of the rise height and sag height, the self-weight and initial prestress level of the entire structure can be obtained. Because the self-weight of the cables decreases with increasing of the rise height and sag height, while the self-weight of the inner strut increases, the total weight of the entire structure successively exhibits a sharp reduction, a gradual decrease, a slow increase, and a sharp increase during the optimization process. For the simplified model, the optimal design corresponds to the combination of rise height and sag height that results in an appropriate prestress level of the entire structure with the minimum total weight.

• Bulletin of the Korean Chemical Society
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• 제19권8호
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• pp.868-874
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• 1998

An equivalent retention has been experimentally observed in thermal field-flow fractionation (ThFFF) for different polymer-solvent systems. It is shown that iso-retention between two sets of polymer-solvent systems can be obtained by adjusting the temperature difference (ΔT) according to the difference in the ratio of ordinary diffusion coefficient to thermal diffusion coefficient. This method uses a compensation of field strength (ΔT) in ThFFF at a fixed condition of cold wall temperature. It is applied for the calculation of molecular weight of polymers based on a calibration run of different standards obtained at an adjusted AT. The polymer standards used in this study are polystyrene (PS), polymethylmethacrylate (PMMA), and polytetrahydrofuran (PTHF). Three carrier solvents, tetrahydrofuran (THF), methylethylketone (MEK) and ethylacetate (ETAc) were employed. Though the accuracy in the calculation of molecular weight is dependent on the difference in the slope of log λ vs. log M which is related to Mark-Houwink constant a, it shows reasonable agreement within about 6% of relative error in molecular weight calculation for the polymer-solvent systems having similar a value.

• Nuclear Engineering and Technology
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• 제49권6호
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• pp.1172-1180
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• 2017

The application of Monte Carlo (MC) to large-scale fixed-source problems has recently become possible with new hybrid methods that automate generation of parameters for variance reduction techniques. Two common variance reduction techniques, weight windows and source biasing, have been automated and popularized by the consistent adjoint-driven importance sampling (CADIS) method. This method uses the adjoint solution from an inexpensive deterministic calculation to define a consistent set of weight windows and source particles for a subsequent MC calculation. One of the motivations for source consistency is to avoid the splitting or rouletting of particles at birth, which requires computational resources. However, it is not always possible or desirable to implement such consistency, which results in inconsistent source biasing. This paper develops an original framework that mathematically expresses the coupling of the weight window and source biasing techniques, allowing the authors to explore the impact of inconsistent source sampling on the variance of MC results. A numerical experiment supports this new framework and suggests that certain classes of problems may be relatively insensitive to inconsistent source sampling schemes with moderate levels of splitting and rouletting.

• Structural Engineering and Mechanics
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• 제57권2호
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• pp.281-294
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• 2016

The paper is devoted to study a mesh-free analysis method of structural elements of engineering structures based on B-spline Wavelet Basis Function. First, by employing the moving-least square method and the weighted residual method to solve the structural displacement field, the control equations and the stiffness equations are obtained. And then constructs the displacement field of the structure by using the m-order B-spline wavelet basis function as a weight function. In the end, the paper selects the plane beam structure and the structure with opening hole to carry out numerical analysis of deformation and stress. The Finite Element Method calculation results are compared with the results of the method proposed, and the calculation results of the relative error norm is compared with Gauss weight function as weight function. Therefore, the clarification verified the validity and accuracy of the proposed method.