• Proceedings of the Computational Structural Engineering Institute Conference
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• 2008.04a
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• pp.65-70
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• 2008

The capacity spectrum method (CSM) is a deterministic seismic analysis approach wherein the expected seismic response of a structure is established as the intersection of the demand and capacity curves. Recently, there are a few studies about a probabilistic CSM where uncertainties in design factors such as material properties, loads, and ground motion are being considered. However, researches show that soil-structure interaction also affects the seismic responses of structures. Thus, their uncertainties should also be taken into account. Therefore, this paper presents a probabilistic approach of using the CSM for seismic analysis considering uncertainties in soil properties. For application, a reinforced concrete bridge column structure is employed as a test model. Considering the randomness of the various design parameters, the structure's probability of failure is obtained. Monte Carlo importance sampling is used as the tool to assess the structure's reliability when subjected to earthquakes. In this study, probabilistic CSM with and without consideration of soil uncertainties are compared and analyzed. Results show that the analysis considering soil structure interaction yields to a greater probability of failure, and thus can lead to a more conservative structural design.

• Coupled systems mechanics
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• v.7 no.5
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• pp.509-524
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• 2018

A hierarchical multi-scale modeling strategy devoted to the study of a Bitumen-Bound Gravel (BBG) is presented in this paper. More precisely, the paper investigates the temperature-dependent linear viscoelastic of the material when submitted to low deformations levels and moderate number of cycles. In such a hierarchical approach, 3D digital Representative Elementary Volumes are built and the outcomes at a scale (here, the sub-mesoscale) are used as input data at the next higher scale (here, the mesoscale). The viscoelastic behavior of the bituminous phases at each scale is taken into account by means of a generalized Maxwell model: the bulk part of the behavior is separated from the deviatoric one and bulk and shear moduli are expanded into Prony series. Furthermore, the viscoelastic phases are considered to be thermorheologically simple: time and temperature are not independent. This behavior is reproduced by the Williams-Landel-Ferry law. By means of the FE simulations of stress relaxation tests, the parameters of the various features of this temperature-dependent viscoelastic behavior are identified.

• International Journal of Industrial Entomology and Biomaterials
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• v.8 no.1
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• pp.1-15
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• 2004

Due to recent scientific innovations in mulberry cultivation, leaf yield has been increased manifold. However, with successive leaf harvest, a quantum drop in leaf yield and quality has been noted. This inturn has affected the silkworm rearing and farmers suffered by the frequent crop failures. This is mainly due to nutrient deficiencies in mulberry leaf. Moreover, no complete information is available about hunger signs of nutritional disorders, analytical diagnosis and critical levels of nutrients required. The present paper, thus, may serve as an important nutrient guide for identification of hunger signs, leaf nutrients status under deficiency and critical levels of the elements namely N, P, K, Ca, Mg, S, B, Cu, Fe, Mn and Zn requirements for higher leaf yield and quality. The leaf nutrient status provided may help chemist for correcting the soil status. Besides, an integration of mulberry intercropping with legumes and applications of neem and castor oil cakes, VA-mycorrhizal inoculation, biofertilizer and vermicompost are suggested as integrated nutrient management for sustainable sericulture industry. Based on the information described in this paper, a model needs to be framed for maintaining continuous supply of nutrients to obtain desired quantity and quality of mulberry leaf for successful silkworm cocoon crop and increasing overall silk productivity.

• The Bulletin of The Korean Astronomical Society
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• v.38 no.2
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• pp.38.1-38.1
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• 2013

We present the Yonsei evolutionary population synthesis (YEPS) models based on the high-resolution empirical spectral energy distributions (SEDs). We have adopted the MILES library in the optical wavelength, and our new models based on the MILES library show good agreements with our previous models presented in the YEPS I. The effect of hot horizontal-branch (HB) stars on the integrated properties of simple stellar populations (SSPs) is again confirmed by our models based on empirical SEDs. In addition, we have extended our empirical models to the near-IR wavelength and predicted the strengths of the calcium II triplet (CaT) and the Paschen triplet (PaT) based on the INDO-US and the Cenarro library. We find that the effect of HB stars and the age of SSPs on the CaT is almost negligible. On the other hands, the PaT models are very sensitive to the existence of hot stars, e.g., HB stars and young turn-off stars, and show very similar results with Balmer lines. Interestingly, the CaT distribution of GCs in NGC 1407, which is at odds with the optical (B-I) color distribution, can be explained by the unique feature of the CaT-[Fe/H] relations that show almost the same equivalent widths in the metal-rich regime. We will also discuss the impact of the second-generation populations on the strength of the CaT.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.13 no.8
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• pp.598-604
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• 2003

In this paper a general solution method is presented to obtain the unbalance response orbit from the finite element based equations of motion of a gear-coupled two-shaft rotor-bearing system, whose shafts rotate at their different speeds from each other. Particularly, are proposed analytical solutions of the maximum and minimum radii of the orbit. The method has been applied to analyze the unbalance response of a 800 refrigeration-ton turbo-chiller rotor-bearing system having a bull-pinion speed increasing gear. Bumps in the unbalance response of the driven high speed compressor rotor system have been observed at the first torsional natural frequency due to the coupling effect of lateral and torsional dynamics. Further, the proposed analytical solutions have agreed well with those obtained by a full numerical approach. The proposed analytical solutions can be generally applied to obtain the maximum and minimum radii of the unbalance response orbits of dual-shaft rotor-bearing systems coupled by bearings as well.

• Transactions of Materials Processing
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• v.20 no.2
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• pp.132-139
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• 2011

Three dimensional simulations were performed for the deformation of a slab in a roller hearth type slab reheating furnace. The main objective of this study was to examine the deformation pattern of the slab due to the shadow effect, i.e., the temperature difference between the upper and lower slab surfaces, in particular, the variations of displacement and effective stress in the vertical direction. A commercially available FE code, ANSYS Workbench $12.1^{TM}$, was used in a fully coupled thermo-elasticity analysis. Several cases with different slab surface temperatures were selected for the simulations. For the sake of simplicity, the temperature environment inside the furnace was assumed to be homogeneous for the upper and lower faces of the slab. Two cases of with different slab width were selected as model geometry. The deformation patterns were computed and explained in terms of periodicity and symmetry. The results indicated that the shadow effect leads to a significant displacement in the vertical direction and, thereby, is one of the main reasons for the separation of the slab and its supports. These simulations also predicted that the deformation is more severe along the transverse direction than along the longitudinal direction.

• Mycobiology
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• v.48 no.3
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• pp.228-232
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• 2020

Cordyceps is a genus of ascomycete fungi and is well known as one of the important medical fungi in Chinese, Korea, and other Asian countries, because of its various beneficial effects on human health. The pharmacological activities of Cordyceps extract are mainly focused on anti-cancer, anti-metastatic, and immune modulating effects. In the present study, we investigated whether the antiplatelet effect of ethanol extract of cultured Cordyceps militaris (CMEE) with FeCl₃-induced arterial thrombosis model. We observed that CMEE exhibited a significant inhibitory effect against ADP and collagen-induced platelet aggregation. However, there were no significant differences in prothrombin time (PT) and activated partial thromboplastin time (aPTT). These results suggest that antithrombotic activity of CMEE is related to antiplatelet effect rather than anticoagulation effect, and CMEE may be a positive effect on improving blood circulation against vessel injury and occlusion.

• Proceedings of the KSRS Conference
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• 2005.10a
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• pp.378-380
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• 2005

Remote sensing of atmospheric aerosol using MODIS satellite data has been proven to be very useful in global/regional scale aerosol monitoring. Due to their large spatial resolution of $10km^2$ MODIS aerosol optical thickness (AOT) data have limitations for local/urban scale aerosol monitoring applications. Modified Bremen Aerosol Retrieval (BAER) algorithm developed by von Hoyningen-Huene et al. (2003) and Lee et al. (2005) has been applied in this study to retrieve AOT in fe resolutions of $500m^2$ over Korea. Look up tables (LUTs) were constructed from the aerosol properties based on sun-photometer observation and radiation transfer model calculations. It was found that relative error between the satellite products and the ground observations was within about $15\%$. Resulting AOT products were correlated with surface PMIO concentration data. There was good correlation between MODIS AOT and surface PM concentration under certain atmospheric conditions, which supports the feasibility of using the high-resolution MODIS AOT for local and urban scale air quality monitoring

• Journal of the Korean Society for Precision Engineering
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• v.20 no.1
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• pp.205-213
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• 2003

The fiber reinforced composite material is widely used in the multi-industrial field where the weight reduction of the infrastructure is demanded because of their high specific modulus and specific strength. It has two main merits which are to cut down energy by reducing weight and to prevent explosive damage preceding to the sudden bursting which is generated by the pressure leakage condition. Therefore, Pressure vessels using this composite material in comparison with conventional metal vessels can be applied in the field such as defense industry, aerospace industry and rocket motor case where lightweight and the high pressure are demanded. In this paper, for nonlinear finite element analysis of E-glass/epoxy filament winding composite pressure vessel receiving an internal pressure, the standard interpretation model is developed by using the ANSYS, general commercial software, which is verified as the accuracy and useful characteristic of the solution based on Auto LISP and ANSYS APDL. Both the preprocessor for doing exclusive analysis of filament winding composite pressure vessel and postprocessor that simplifies result of analysis have been developed to help the design engineers.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.66 no.9
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• pp.1334-1340
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• 2017

In this paper, a tie-plate shape is optimized by using the numerical technique to reduce the stray load loss of the tie-plate which is a mechanical structure for assembling and supporting of the transformer core. The eddy current loss of the structure is calculated by an electromagnetic field FEM program and the results are compared with 4 different shapes of tie-plates. Since the thickness of the tie-plate is very thin, and the skin depth is very small, the number of FE elements for 3-D transformer model is too big to solve. So, the surface impedance boundary condition (SIBC) is used to reduce the system matrix size and its computing time. To verify the method a 2.5 MVA 22,900/380V distribution transformer is simulated using one objective function and three design variables with some constraints. The final optimized tie-plate has three slots of 6 mm width and 23 mm gap, and the loss is reduced by 75 %. Consequently, the proposed algorithm seems to be considerably applicable to electric machinery as well as power transformer.