• Smart Structures and Systems
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• v.15 no.5
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• pp.1373-1392
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• 2015

Placing sensors at appropriate locations is an important task in the design of an efficient structural health monitoring (SHM) system for a large-scale civil structure. In this paper, a hybrid optimization algorithm called virus monkey algorithm (VMA) based on the virus theory of evolution is proposed to seek the optimal placement of sensors. Firstly, the dual-structure coding method is adopted instead of binary coding method to code the solution. Then, the VMA is designed to incorporate two populations, a monkey population and a virus population, enabling the horizontal propagation between the monkey and virus individuals and the vertical inheritance of monkey's position information from the previous to following position. Correspondingly, the monkey population in this paper is divided into the superior and inferior monkey populations, and the virus population is divided into the serious and slight virus populations. The serious virus is used to infect the inferior monkey to make it escape from the local optima, while the slight virus is adopted to infect the superior monkey to let it find a better result in the nearby area. This kind of novel virus infection operator enables the coevolution of monkey and virus populations. Finally, the effectiveness of the proposed VMA is demonstrated by designing the sensor network of the Canton Tower, the tallest TV Tower in China. Results show that innovations in the VMA proposed in this paper can improve the convergence of algorithm compared with the original monkey algorithm (MA).

• Structural Engineering and Mechanics
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• v.35 no.6
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• pp.677-697
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• 2010

This paper focuses on geometrically non-linear static analysis of a simply supported beam made of hyperelastic material subjected to a non-follower transversal uniformly distributed load. As it is known, the line of action of follower forces is affected by the deformation of the elastic system on which they act and therefore such forces are non-conservative. The material of the beam is assumed as isotropic and hyperelastic. Two types of simply supported beams are considered which have the following boundary conditions: 1) There is a pin at left end and a roller at right end of the beam (pinned-rolled beam). 2) Both ends of the beam are supported by pins (pinned-pinned beam). In this study, finite element model of the beam is constructed by using total Lagrangian finite element model of two dimensional continuum for a twelve-node quadratic element. The considered highly non-linear problem is solved by using incremental displacement-based finite element method in conjunction with Newton-Raphson iteration method. In order to use the solution procedures of Newton-Raphson type, there is need to linearized equilibrium equations, which can be achieved through the linearization of the principle of virtual work in its continuum form. In the study, the effect of the large deflections and rotations on the displacements and the normal stress and the shear stress distributions through the thickness of the beam is investigated in detail. It is known that in the failure analysis, the most important quantities are the principal normal stresses and the maximum shear stress. Therefore these stresses are investigated in detail. The convergence studies are performed for various numbers of finite elements. The effects of the geometric non-linearity and pinned-pinned and pinned-rolled support conditions on the displacements and on the stresses are investigated. By using a twelve-node quadratic element, the free boundary conditions are satisfied and very good stress diagrams are obtained. Also, some of the results of the total Lagrangian finite element model of two dimensional continuum for a twelve-node quadratic element are compared with the results of SAP2000 packet program. Numerical results show that geometrical nonlinearity plays very important role in the static responses of the beam.

• Polymer(Korea)
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• v.25 no.2
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• pp.240-245
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• 2001

The effect of additives on the orientation of magnetic Sr-ferrite powders has been studied during powder injection molding under applied magnetic field for fabricating multi-pole anisotropic sintered Sr-ferrite magnets. The orientation of the Sr-ferrite powders depends sensitively on the fluidity of powder-binder mixture, related to the binder additives and the injection molding temperature, and the magnetic field intensity. The orientation of Sr-ferrite powders is good for the compacts with stearic acid added in the binder system of paraffin wax/carnauba wax/HDPE, but it is poor for the compacts with silane coupling agent added. The orientation of Sr-ferrites higher than 80% is achieved at the following useful conditions; apparent viscosity lower than 2500 poise in 1000 sec$^{-1}$ shear rate and applied magnetic field higher than 4 kOe.

• Polymer(Korea)
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• v.35 no.2
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• pp.136-140
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• 2011

The plasma resistances of nitrile curable perfluoro elastomer (NT PFE) and peroxide curable PFE (PO PFE) after exposing to $NF_3$ and $O_2$ remote plasmas were investigated by analyzing weight loss and morphology of O-ring made of PFE. The compounds were designed following the typical formulations of O-ring/seal which were applied in semiconductor and LCD production site. They were blended by an open roll mill, and then, O-ring was finally made by hot press molding and oven curing. The weight loss was calculated and morphology was observed for each atmosphere and temperature by a digital weighing machine and SEM. As results, it was confirmed the weight loss and related morphology were meaningfully different according to the cure type of PFE, filler system, and the species of remote plasma.

• Hwankyungkyoyuk
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• v.13 no.2
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• pp.51-62
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• 2000

This study examined the current status of school environmental education (EE) in Germany, and attempted to propose strategies to develop school EE in Korea. The study intended to accomplish the following goals: First, this study attempted to examine the developmental process of school EE in Germany. Second, exemplary cases of site-based experiential education in Germany are selected and analysed to develop pedagogical strategies in school EE in Korea. The strategies for development proposed in this study can be summarized as follows: First, the focus of EE should go beyond that of "solving or curing"environmental problems and pollutions, and need to be re-directed to pursue an "education for sustainable development", a new paradigm for future EE. Second, EE should increasingly integrate outdoor site-based, experiential programs into the currently classroom-based and knowledge-driven forms of education, not only to maximize its educational effect but also and knowledge-driven forms of education, not only to maximize its educational effect but also to coordinate the instruction of EE in the context of the educational reform agenda, currently undergoing since the late 1990s, in Korea. Third, teaching-learning materials for EE should be variously developed, and programs should be encouraged to serve local needs and circumstances for effective classroom practices, and criteria for standardization and professionalization should be sought in developing these programs. Fourth, it is recommended that the Ministry of Environment secure funds to facilitate the local school authorities at the municipal and provincial levels to operate a mobile environmental support system, equivalent to the function of the "Lumbricus"in Germany. Fifth, an external support network should be established among the support agencies for EE. Especially, a professional agency or institute to academically support school EE and a special planning committee for enhancing EE need to be established for resource and personal development. Parents′voluntary participation should also be encouraged to establish a tripartite network of "school-community-government" to support and facilitate school EE.

• Safety and Health at Work
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• v.6 no.1
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• pp.56-61
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• 2015

Frozen food processing workers work under a cold environment which can cause several adverse health effects.This study explored factors affecting workers' health in the frozen food industry in Thailand. Participants comprised 497 workers exposed to a cold working environment and 255 office workers who served as the controls. Data were collected by a survey on the work environment, and the interview of workers for abnormal symptoms. The exposed group had the following characteristics: 52.7% male, overall average age of 27 (SD 6.6) years old, attained elementary education (Grade 4 and Grade 6) (54.1%), married (48.9%), smokers (21.3%), alcohol consumption (31.0%), duration of work was between 1 and 5 years (65.2%), working 6 days a week (82.7%), 1-5 hours of overtime per week (33.8%), office workers (33.9%); work category: sizing (6.9%), peeling (28.3%) dissecting (22.2%), and in the warehouse (8.6%). The temperature in the work environment ranged from $17.2^{\circ}C$ to $19.2^{\circ}C$ in most sections, $-18.0^{\circ}C$ in the warehouse, and $25^{\circ}C$ in the office areas. Warehouse workers had more abnormal symptoms than controls including repeated pain in the musculoskeletal system (OR 11.9; 95% CI 6.12-23.45), disturbance throughout the body (OR 4.60; 95% CI 2.00-10.56), respiratory symptoms (OR 9.73; 95% CI 3.53-26.80), episodic finger symptoms (OR 13.51; 95% CI 5.17-35.33). The study results suggest that workers' health should be monitored especially with regard to back and muscle pain, respiratory symptoms, episodic finger symptoms, and cardiovascular symptoms. Health promotion campaigns such as antismoking and reduction of alcohol consumption should be established because smoking and alcohol consumption are contributing factors to the pathogenesis of Raynaud's phenomenon and peripheral vascular disorders such as hypertension and heart disease.

• Nuclear Engineering and Technology
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• v.51 no.8
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• pp.2005-2012
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• 2019

This work investigated the radiation attenuation characteristics of three series of tellurite glass systems with the following compositions: 30PbO-10ZnO-xTeO₂-(60-x)B₂O₃ where x = 10, 30, 40, 50 and 60 mol%, xBaO-xB₂O₃-(100-2x)TeO₂ with x = 15-40 mol% and 50ZnO-(50-x)P₂O₅-xTeO₂, where x = 0, 10, .40 mol%. The results revealed that the attenuation parameters in all the samples decrease with increase in the energy, which implied that all the samples have better interaction with gamma photons at low energies and thus higher photon attenuating efficiency. From the three systems, the samples coded as PbZnBTe60, BaBTe70 and ZnPTe40 have the lowest half value layer values and accordingly have superior photon attenuation efficacy. The maximum effective atomic number values were found for energy less than 0.1 MeV particularly near the K-edges absorption of the heavy atomic number elements such as Te, Ba and Pb. At the lowest energy, the Z_eff values are found in the range of 62.33-66.25, 49.43-50.81 and 24.99-35.83 for series 1-3 respectively. Also, we found that the density of the glass remarkably affects the photon attenuation ability of the selected glasses. The mean free path results showed that the PbO-ZnO-TeO₂-B₂O₃ glass system has better radiation shielding efficiency than the glass samples in series 2 and 3.

• Journal of Korean Society of Industrial and Systems Engineering
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• v.41 no.1
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• pp.70-83
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• 2018

Korea's five leading industries-chemical, automobile, shipbuilding, metal and electronics-have been the growth engines of the Korean economy for the last 30 years. However, with their performance weakening in the past few years, Korea's annual growth rate has dropped to less than 2%. Just as the Japanese economy struggled through the lost decades, Korea's leading industries have been facing signals of arriving at a Strategic Inflection Point ("SIP") since the mid-2000s. The objective of this study is to present an appropriate value strategy for Korean firms in leading industries to gain sustainable competitive advantages. This paper examines the following issues : First, it diagnoses the signs and timing of SIP for the five leading industries. Second, this study examines 78 Korean and Japanese firms in order to understand the adaptation strategies of the highest and lowest performing firms from a value strategy point of view. Third, it empirically analyzes the correlation between the indicators of value strategy and the accounting performances of the Korean and Japanese firms. The data set used in the cluster analysis were collected from KISLINE database of NICE Information Service and annual reports. The findings in the case analyses of high and low performing companies show that high value-added specialty chemical materials and electronic component manufacturers that had a strong focus on value creation were defined as high performing companies. And in the cosmetic and automobile industries, companies with a strong emphasis on value appropriation gained high performance. Furthermore, the study conducted a cluster analysis based on two indicators R&D and advertisement expense. The analysis shows that a significant gap exists in the operating incomes among three groups classified under the value strategy. The study recommends that Korean firms are requested to increase R&D expenditure, conduct M&A and collaborate with companies that own source technologies to narrow the technology gap and improve their segment portfolio from commodity to value-added products.

• Journal of Ginseng Research
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• v.30 no.3
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• pp.106-111
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• 2006

Adverse changes in individual's biochemistry under heavy metal stress are directly linked with its metabolic activity and health status. The present investigation highlights the differences in protecting role of Panax ginseng extract against mercuric chloride induced alterations in serum proteins. The assessment was based on dividing fifty albino rats into two sets, one for acute and the other for sub-acute study. All the sets had five groups with five albino rats in each i.e. control group, mercuric chloride treated group, Panax ginseng extract treated group, mercuric chloride followed by Panax ginseng extract treated group and Panax ginseng extract followed by mercuric chloride treated group. Mercuric chloride was given orally 0.926 mg/kg body weight for acute set and 0.044 mg/kg body weight for sub-acute set after LD50 (9.26 mg/kg body weight) determination by probitt analysis. 10 mg/kg body weight Panax ginseng extract was given in both acute and sub-acute sets after incorporating safety trials. The control group received tween-20 and distilled water only. The result exhibited significantly reduction (P<0.01) in serum protein, albumin and globulin following mercuric chloride intoxication whereas significant (P<0.01) enhancement in other groups with Panax ginseng extract as an ingredient confirming its protective role. All serum samples were also electrophoresed in 10% SDS with standard marker using discontinuous buffering system. Gradual disappearance of alpha-2 and beta-1 globulin bands from electrophoretic pattern was observed, while a single sharp band was observed between beta-2 and gamma globulin in serum protein pattern of acutely mercuric chloride treated rats. However, this band could not be visualized in sub-acute studies. Panax ginseng extract exhibits a better protection after acute intoxication.

• YAKHAK HOEJI
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• v.41 no.1
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• pp.48-59
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• 1997

Sustained release matrix tablets, pellets, and coated pellets for the delivery of sulindac were prepared using cellulose derivatives at various ratios, and evaluated for the dis solution pattern. The release of sulindac, from matrix tablets prepared with low viscosity HPMC was relatively fast, and especially the tablets made of Metolose SM released all of sulindac within 1 hr. The release of drug from tablets made of other HPMC derivatives were retarded in the order of the following: Pharmacoat 645>Pharmacoat 606>Pharrnacoat 606+HPC-L>HPC-L. The most sustained release pattern was observed with the preparation of high viscous polymer. Metolose 90 SH. While release of sulindac, from matrix type pellet containing 10mg/cap of Metolose 90 SH or 60 SH was completed within 1 hr, a prolonged release formulation (30% in 1 hr) was obtained by the inclusion of EC. Pellets coated with HPMC showed a fast release pattern (${\geq}$ 80% within 2 hrs), whereas pellets coated with HPMC and EC (molar ratio 1 : 1) showed a sustained release pattern (${\geq}$ 80% in 12 hrs), vath the release from EC pellets being the most sustained. Fast (naked) and slow release pellets coated with EC, Metolose 60SH 50cps and propylene glycol. and enteric pellets coated with HPMCP 55 and Myvacet$^{\circledR}$ were prepared, and combined at various ratios for the assessment of dissolution pattern. The result indicates the possibility that the development of 24 hr sustained release delivery systems containing sulindac for oral administration could be achieved by means of combining sustained and fast release pellets at a proper portion.