• 한국정밀공학회지
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• 제28권3호
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• pp.265-274
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• 2011

This paper presents current state of the prediction simulator of structural characteristics of machinery equipment accuracy. Developed accuracy prediction simulator proceeds and estimates the structural analysis between the designer and simulator through the internet for convenience of designer. 3D CAD model which is input to the accuracy prediction simulator would simplified by the process of removing the small hole, fillet and chamfer. And the structural surface joints would be presented as the spring elements and damping elements for the structural analysis. The structural analysis of machinery equipment joints, containing rotary motion unit, linear motion unit, mounting device and bolted joint, are presented using Finite Element Method and their experiment. Finally, a general method is presented to tune the static stiffness at a rotation joint considering the whole machinery equipment system by interactive use of Finite Element Method and static load experiment.

• Ocean and Polar Research
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• 제34권2호
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• pp.185-195
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• 2012

This paper focused on forecasting a short-term production of oysters, which have been farmed in Korea, with distinct periodicity of production by year, and different production level by month. To forecast a short-term oyster production, this paper uses monthly data (260 observations) from January 1990 to August 2011, and also adopts several econometrics methods, such as Multiple Regression Analysis Model (MRAM), Seasonal Autoregressive Integrated Moving Average (SARIMA) Model, and Vector Error Correction Model (VECM). As a result, first, the amount of short-term oyster production forecasted by the multiple regression analysis model was 1,337 ton with prediction error of 246 ton. Secondly, the amount of oyster production of the SARIMA I and II models was forecasted as 12,423 ton and 12,442 ton with prediction error of 11,404 ton and 11,423 ton, respectively. Thirdly, the amount of oyster production based on the VECM was estimated as 10,425 ton with prediction errors of 9,406 ton. In conclusion, based on Theil inequality coefficient criterion, short-term prediction of oyster by the VECM exhibited a better fit than ones by the SARIMA I and II models and Multiple Regression Analysis Model.

• 대한조선학회논문집
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• 제41권2호
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• pp.106-113
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• 2004

The block assembly of ship consists of a certain type of heat processes such as cutting, bending, welding, residual stress relaxation and fairing. The residual deformation due to welding is inevitable at each assembly stage. The geometric inaccuracy caused by the welding deformation tends to preclude the introduction of automation and mechanization and needs the additional man-hours for the adjusting work at the following assembly stage. To overcome this problem, a distortion control method should be applied. For this purpose, it is necessary to develop an accurate prediction method which can explicitly account for the influence of various factors on the welding deformation. Systematic and quantitative theoretical works to clarify the effects of various factors on the welding deformation have rarely been found. Therefore, in this paper, the effects of various factors, such as welding process and gravity on the butt welding deformation have been investigated through a number of numerical analyses. In addition, this paper proposes a simplified analysis method to predict the butt welding deformation in actual plate structure. For this purpose, a simple prediction model for butt welding deformations has been derived based on numerical and experimental results through the regression analysis. Based on these results, the simplified analysis method has been applied to some examples to show its validity.

• Computers and Concrete
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• 제13권4호
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• pp.531-545
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• 2014

The purpose of this paper is to develop a prediction model for the compressive strength of waste LCD glass applied in concrete by analyzing a series of laboratory test results, which were obtained in our previous study. The hyperbolic function was used to perform the nonlinear-multivariate regression analysis of the compressive strength prediction model with the following parameters: water-binder ratio w/b, curing age t, and waste glass content G. According to the relative regression analysis, the compressive strength prediction model is developed. The calculated results are in accord with the laboratory measured data, which are the concrete compressive strengths of different mix proportions. In addition, a coefficient of determination $R^2$ value between 0.93 and 0.96 and a mean absolute percentage error MAPE between 5.4% and 8.4% were obtained by regression analysis using the predicted compressive analysis value, and the test results are also excellent. Therefore, the predicted results for compressive strength are highly accurate for waste LCD glass applied in concrete. Additionally, this predicted model exhibits a good predictive capacity when employed to calculate the compressive strength of washed glass sand concrete.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2004년도 추계학술대회
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• pp.7-12
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• 2004

A lifetime prediction of holddown spring screw in nuclear fuel assembly was performed using fracture mechanics approach. The spring screw was designed such that it was capable of sustaining the loads imposed by the initial tensile preload and operational loads. In order to investigate the cause of failure and to predict the stress corrosion cracking life of the screw, a stress analysis of the top nozzle spring assembly was done using finite element analysis. The elastic-plastic finite element analysis showed that the local stresses at the critical regions of head-shank fillet and thread root significantly exceeded than the yield strength of the screw material, resulting in local plastic deformation. Normalized stress intensity factors for PWSCC life prediction was proposed. Primary water stress corrosion cracking life of the Inconel 600 screw was predicted by using integration of the Scott model and resulted in 1.78 years, which was fairly close to the actual service life of the holddown spring screw.

• 유체기계공업학회:학술대회논문집
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• 유체기계공업학회 2006년 제4회 한국유체공학학술대회 논문집
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• pp.547-550
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• 2006

An analysis method is developed for the prediction of venting in multiple compartments which are connected in series or parallel through multiple ports. The existing method by the authors is modified to remove the limitation in number of ports and compartments, and the more general polytropic relation or solution of the additional energy equation replaces the previous isentropic relation allowing the prediction of pressure rise in addition to pressure drop. The accuracy of the method is verified by comparison with the results by NASA Flap code for the problem of pressure drop in a payload in the Space Shuttle cargo bay. It is expected that this method will be a useful tool in prediction of the pressure variation in a payload or payload capsule without mentioning the payload fairing itself.

• 대한기계학회논문집
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• 제14권2호
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• pp.276-287
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• 1990

In this paper research result of transient thermal stress analysis of power plant turbine rotors for life prediction under severs operating conditions is presented. Galerkin's recurrence scheme is used for numerical solution of discretized FEM equation of transient heat conduction equation. Boundary conditions for the equation and operating conditions are intensively investigated for accurate life prediction of turbine rotors in operation. A computer program for on-site application is developed and tested. Distribution of thermal stress in turbine rotors during various operating condition is analyzed with the program and it is found that the peak thermal stress appears during cold stage conditions at the first stage of high pressure rotors.

• 한국소음진동공학회:학술대회논문집
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• 한국소음진동공학회 2002년도 춘계학술대회논문집
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• pp.948-954
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• 2002

The structural vibration of a diesel generator set was investigated through analyses and tests. FE modeling and normal mode analysis were performed and compared with measured results for both structure components and generator set assembly. The results of component analyses were fairly well coincident with measured results but those of assembled generator set showed more or less discrepancies. Discussions were given about the uncertainties for vibration characteristics of component structures and assembled running structures especially concerning their nonlinearities and damping effects. Detailed excitation analysis fellowed by forced response analysis was done from the engine and pressure data to compare with the actual measured vibration. As results the vibration prediction for frame structures of reciprocating internal combustion engine was confirmed reliable to some extent.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 춘계 학술발표회
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• pp.146-153
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• 2009

One dimensional site response analysis is widely used in prediction of the ground motion that is induced by earthquake. Equivalent linear analysis is the most widely used method due to its simplicity and ease of use. However, the equivalent linear method has been known to be unreliable since it approximates the nonlinear soil behavior within the linear framework. To consider the nonlinearity of the ground at frequency domain, frequency dependent algorithms that can simulate shear strain - frequency dependency have been proposed. In this study, the results of the modified equivalent linear analysis are compared to evaluate the degree of improvement and the applicability of the modified algorithms. Results show the novel smoothed curve that is proposed by this study indicates the most stable prediction and can enhance the accuracy of the prediction.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 2009년도 세계 도시지반공학 심포지엄
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• pp.1202-1205
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• 2009

Embankment preloading, in conjunction with prefabricated vertical (PV) drains, was used to accelerate consolidation of marine clays in Pusan New Harbour project. UP to eightteen settlement plates were installed at the ground reclamated site under the embankment fill to monitor the preload performance. This analysis is carried out by five settlement prediction methods including the Asaoka, Hyperbolic, Hoshino, and back-analysis method based on optimization. The field settlement data can be analysed by settlement prediction methods to predict the ultimate settlement and the degree of consolidation of the reclaimed land under charge fill. The authors compared with the analyzed results of the methods.