• International Journal of Industrial Entomology and Biomaterials
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• v.21 no.1
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• pp.139-143
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• 2010

The objective of our study was the formulation of a local strain of Mamestra brassicae nucleopolyhedrovirus-K1 (MabrNPV-K1) for the development of viral insecticide to control M. brassicae. To formulate MabrNPV-K1, feeding toxicities of various supplements and ultraviolet (UV)-protection were investigated. Optical brightener Tinopal UNPA-GX (Tinopal) as UV protectant and Bentonite had some toxicity themselves to increase the mortality. The protection of polyhedra from UV light radiation was observed only by Tinopal. The MabrNPV-K1 was formulated as a wettable powder form. The mortality of the formulation was higher and rapid than that of the un-formulated. This suggested the possibility of MabrNPV-K1 formulation as an effective biological control agent for M. brassicae.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2005.10a
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• pp.105-110
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• 2005

The penalty method has been widely applied to analyses of incompressible fluid flow. However, we have not yet found any prior studies that employed penalty method to analyze compressible fluid flow. In this study, with an eye on the apparent similarity between the slight compressible formulation and the penalty formulation, we have proposed a modified approximate approach that can analyze compressible packing process using the penalty parameter, which is an improvement on an earlier formulation (KSME, 2004B). Based on the assumption of the isothermal flow, a set of reference solutions was obtained to verify the validity of the proposed scheme. Furthermore, we have applied the proposed scheme to the analysis of the packing process of different cases.

• Structural Engineering and Mechanics
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• v.51 no.4
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• pp.601-625
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• 2014

Based on continuum mechanics and the principle of virtual displacements, incremental total Lagrangian formulation (T.L.) and incremental updated Lagrangian formulation (U.L.) were presented. Both T.L. and U.L. considered the large displacement stiffness matrix, which was modified to be symmetrical matrix. According to the incremental updated Lagrangian formulation, small strain, large displacement, finite rotation of three dimensional Timoshenko fiber beam element tangent stiffness matrix was developed. Considering large displacement and finite rotation, a new type of tangent stiffness matrix of the beam element was developed. According to the basic assumption of plane section, the displacement field of an arbitrary fiber was presented in terms of nodal displacement of centroid of cross-area. In addition, shear deformation effect was taken account. Furthermore, a nonlinear finite element method program has been developed and several examples were tested to demonstrate the accuracy and generality of the three dimensional beam element.

• Structural Engineering and Mechanics
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• v.68 no.2
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• pp.237-245
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• 2018

This study proposes an empirical formulation to predict the maximum deformation of offshore blast wall structure that is subjected to impact loading caused by hydrocarbon explosion. The blast wall model is assumed to be supported by a simply-supported boundary condition and corrugated panel is modelled. In total, 1,620 cases of LS-DYNA simulations were conducted to predict the maximum deformation of blast wall, and they were then used as input data for the development of the empirical formulation by regression analysis. Stainless steel was employed as materials and the strain rate effect was also taken into account. For the development of empirical formulation, a wide range of parametric studies were conducted by considering the main design parameters for corrugated panel, such as geometric properties (corrugation angle, breadth, height and thickness) and load profiles (peak pressure and time). In the case of the blast profile, idealised triangular shape is assumed. It is expected that the obtained empirical formulation will be useful for structural designers to predict maximum deformation of blast wall installed in offshore topside structures in the early design stage.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.29 no.6 s.237
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• pp.860-875
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• 2005

A new meshfree method for the analysis of elasto-plastic deformations is presented. The method is based on the proposed first-order least-squares formulation, to which the moving least-squares approximation is applied. The least-squares formulation for the classical elasto-plasticity and its extension to an incrementally objective formulation for finite deformations are proposed. In the formulation, the equilibrium equation and flow rule are enforced in least-squares sense, while the hardening law and loading/unloading condition are enforced exactly at each integration point. The closest point projection method for the integration of rate-form constitutive equation is inherently involved in the formulation, and thus the radial-return mapping algorithm is not performed explicitly. Also the penalty schemes for the enforcement of the boundary and frictional contact conditions are devised. The main benefit of the proposed method is that any structure of cells is not used during the whole process of analysis. Through some numerical examples of metal forming processes, the validity and effectiveness of the method are presented.

• Computational Structural Engineering
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• v.9 no.3
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• pp.179-186
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• 1996

A simple nonlinear programming(NLP) formulation for the optimal topology problem of structures is developed and examined. The NLP formulation is general, and can handle arbitrary objective functions and arbitrary stress, displacement constraints under multiple loading conditions. The formulation is based on simultaneous analysis and design approach to avoid stiffness matrix singularity resulting from zero sizing variables. By embedding the equilibrium equations as equality constraints in the nonlinear programming problem, we avoid constructing and factoring a system stiffness matrix, and hence avoid its singularity. The examples demonstrate that the formulation is effective for finding an optimal solution, and shown to be robust under a variety of constraints.

• Computational Structural Engineering
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• v.7 no.4
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• pp.69-83
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• 1994

An explicit finite element nonlinear formulation for very large deformations of plane frame structures is developed. The formulation is based on an updated material reference frame and hence a true stress-strain relationship can be directly applied to characterize the properties of material which is subjected to very large deformations. In the formulation, a co-rotational approach is applied to deal with the large rotations but small strain problems. Straight beam element is considered when the strain of an element is large. The element formulation is based on the small deflection beam theory but with the inclusion of the effect of axial force. The element equations are constructed in an element local coordinate system which rotates and translates with the element, and then transformed to the global coordinate system. Several numerical examples are analyzed to validate the presented formulation.

• Journal of Korean Society of Occupational and Environmental Hygiene
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• v.22 no.2
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• pp.91-99
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• 2012

Airborne chlorpyrifos concentrations in formulation workplaces have not been determined in Korea. The aim of the study was to evaluate chlorpyrifos concentrations of air in a formulation workplace and recognize the RBC cholinesterase activities for the formulation workers. 30 air samples (personal or area sampling) were collected and bood samples from 10 workers were collected for RBC chlorinesterase (RBC AChE) activity in a factory on May 2008. Air samples were collected by the National Institute for Occupational Safety and Health (NIOSH) method and were analyzed by GC-MS. Airborne chlorpyrifos concentrations ranged from 0.003 to $12.90mg/m^3$ and geometric mean (GM) was $0.15\;mg/m^3.$ Compared to Korean Occupational Exposure Limit (KOEL) of 0.1 (2011) or $0.2\;mg/m^3$ (2008), at 95% confidence, airborne concentrations exceeded the KOEL 69.7% or 56.1% of the time or less, indicating that this concentration level was unacceptable according to exposure assessment using a LogNorm2$^{(R)}$. Since the workers were continually at work on the organophosphate or carbamate pesticides formulation, individual baseline for RBC AChE activity was not determined. As the results of comparison with reference average value of RBC AChE activity, it was found that a worker was below 70% RBC AChE activity and five workers were abnormal.

• Integrative Medicine Research
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• v.3 no.1
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• pp.25-33
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• 2014

Background: Green tea contains numerous polyphenols, which have health-promoting effects. The purpose of this study was to evaluate the effect of tannase-converted green tea extract (TGE) formulation on the physical stability and activities of skin-related enzymes. Methods: Physical stability was evaluated by measuring the pH, precipitation, and colors at $25{\pm}2^{\circ}C$ /ambient humidity and at $40{\pm}2^{\circ}C$ \70%${\pm}$5% relative humidity for 4 months. Activities of collagenase, elastase, and tyrosinase as skin-related enzymes were assessed on TGE formulation. Results: The concentrations of epigallocatechin-3-gallate and epicatechin-3-gallate in green tea extract were greatly decreased to the extent of negligible level when treated with tannase. The formulation containing 5% tannase-converted green tea extract showed relatively stable pH, precipitation, and color features for 16 weeks. When TGE was added to the formulation, there was a significant increase in the inhibition of elastase and tyrosinase activities (p<0.05) compared with the formulation containing 5% normal green tea extract. Conclusion: The TGE could be used in cosmetics as skin antiwrinkling or depigmenting agent.

• Structural Engineering and Mechanics
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• v.69 no.2
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• pp.155-162
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• 2019

It is very common to find an empirical formulation in an earthquake design code to calculate fundamental vibration period of a structural system. Fundamental vibration period or frequency is a key parameter to provide adequate information pertinent to dynamic characteristics and performance assessment of a structure. This parameter enables to assess seismic demand of a structure. It is possible to find an empirical formulation related to reinforced concrete structures, masonry towers and slender masonry structures. Calculated natural vibration frequencies suggested by empirical formulation in the literatures has not suits in a high accuracy to the case of rest of the historical masonry bridges due to different construction techniques and wide variety of material properties. For the listed reasons, estimation of fundamental frequency gets harder. This paper aims to present an empirical formulation through Mean Square Error study to find ambient vibration frequency of historical masonry bridges by using a non-linear regression model. For this purpose, a series of data collected from literature especially focused on the finite element models of historical masonry bridges modelled in a full scale to get first global natural frequency, unit weight and elasticity modulus of used dominant material based on homogenization approach, length, height and width of the masonry bridge and main span length were considered to predict natural vibration frequency. An empirical formulation is proposed with 81% accuracy. Also, this study draw attention that this accuracy decreases to 35%, if the modulus of elasticity and unit weight are ignored.