• Proceedings of the Korean Society for Technology of Plasticity Conference
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• 2007.05a
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• pp.279-280
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• 2007

In this study, it is investigated that the effect of material properties such as various temperature, forming speed and strain rates on formability and forming limits of Mg alloy sheet in square cup deep drawing. Since the sheet metal forming of Mg alloy is perform at elevated temperature, the effect of strain rates related with the forming temperature and forming speed is very important factor for formability and forming limits. Therefore, the investigation for process variables is necessary to improve formability and forming limits. Also, the effects of strain rate and thickness transformation were studied by the experimental and FE analysis using the square cup deep drawing. The temperature, forming speed, and strain rates were investigated. Forming of Mg alloy takes consider into temperature, proper forming speed and strain-rate the formed parts were good without defects fur forming limits.

• Korean Journal of Environmental Biology
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• v.23 no.4
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• pp.357-361
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• 2005

The exposed strain of C. riparius treated with di (ethyl- hexyl)-phthalate (DEHP) did not result in a consistent relationship between mortality or sex ratio and chemical concentrations. And after treating with DEHP, the emergent female from the exposed strain appeared to be fatty with a large body volume comparing with the non - exposed strain. The emergent period (EP) was especially different between the exposed fourth strain and the non-exposed strain; generally the exposed strain was $7\~10$ days, and non - exposed strain was $17\~24$ days. Regarding sustainable exposed effects, the EP, the first emergent day (FED), and the body volume (BV) could be suggested as suitable bio - markers for detecting of exposure to various EDCs.

• Transactions of Materials Processing
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• v.24 no.5
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• pp.348-353
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• 2015

The PEPS(Polar-coordinated Effective Plastic Strain) FLD(Forming Limit Diagram), a new type of FLD based on a polar representation of the EPS(Effective Plastic Strain), appears to be an effective solution to the problem of non-linear strain path effects. This method has the advantages of the familiar strain-based diagram for linear loading, but without the strain-hardening limitations of the stress-based diagram, or non-intuitive aspects of alternate Cartesian diagrams based on effective plastic strain. In the current study, the PEPS FLD was applied to the development process of an aluminum automobile-body panel, including the necking or crack prediction, die design, and die modification. As a result, the PEPS FLD provided improved formability of aluminum sheet as compared to deriving the potential formability with non-linearity.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2000.06a
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• pp.519-524
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• 2000

The types of responses which are generally measured in the modal testing are displacement, velocity or acceleration. In strain modal testing, however, strain responses subject to excitation forces are measured. In this paper, the characteristics of strain modal testing are investigated experimentally. Investigated are the effects of frequency range, excitation force level, and excitation signal on the quality of measured strain frequency response functions. It has been shown that a strain FRF at a point can be predicted from displacement FRFs and strain FRFs at other points.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.14 no.9 s.90
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• pp.819-826
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• 2004

A multi-step optimum strategy for the selection of the locations and directions of strain gauges is proposed in this paper to capture at best the modal response of blade in a series of modes on fan blades. It is consist of three steps including two pass reduction step, genetic algorithm and fine optimization to find the locations-directions of strain gauges. The optimization is based upon the maximum signal-to-noise ratio(SNR) of measured strain values with respect to the inherent system measurement noise, the mispositioning of the gauge in location and gauge failure. Optimal gauge positions for a fan blade is analyzed to prove the effectiveness of the multi-step optimum methodology and to investigate the effects of the considering parameters such as the mispositioning level, the probability of gauge failure, and the number of gauges on the optimal strain gauge position.

• Fashion & Textile Research Journal
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• v.18 no.6
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• pp.733-745
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• 2016

This paper provides a review of wearable textile strain sensors that can measure the deformation of the body surface according to the movements of the wearer. In previous studies, the requirements of textile strain sensors, materials and fabrication methods, as well as the principle of the strain sensing according to sensor structures were understood; furthermore, the factors that affect the sensing performance were critically reviewed and application studies were examined. Textile strain sensors should be able to show piezoresistive effects with consistent resistance-extension in response to the extensional deformations that are repeated when they are worn. Textile strain sensors with piezoresistivity are typically made using conductive yarn knit structures or carbon-based fillers or conducting polymer filler composite materials. For the accuracy and reliability of textile strain sensors, fabrication technologies that would minimize deformation hysteresis should be developed and processes to complement and analyze sensing results based on accurate understanding of the sensors' resistance-strain behavior are necessary. Since light-weighted, flexible, and highly elastic textile strain sensors can be worn by users without any inconvenience so that to enable the users to continuously collect data related to body movements, textile strain sensors are expected to become the core of human interface technologies with a wide range of applications in diverse areas.

• The Journal of Korean Academy of Prosthodontics
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• v.42 no.2
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• pp.154-166
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• 2004

Statement of problem: In distal extension removable partial denture, the preservation of health of abutment teeth are very important, but they are always subjected to unfavorable stress. Purpose: The purpose of this study was performed to investigate the effects of abutment splinting and design of direct retainer on the stress distribution of abutments in unilateral distal extension removable partial dentures. Material and method: Abutments were splinted by different method. In group 1, autment teeth were not splinted, in group 2, canine and 1st premolar were splinted, and in group 3, canine, 1st and 2nd premolars were all splinted. Three different types of direct retainer such as Akers clasp, RPI clasp, and wrought wire clasp were designed. Strain was measured with Switch & Balance Unit(SB-10, Measurement Group Instruments Division, Raleigh USA) and Strain Indicator(P-3500, Measurement Group Instruments Division, Raleigh, USA) 15kg of vertical and oblique loads was applied at central fossa of missing 2nd molar area. Results : The strain on lingual side of 2nd premolar was the greatest, and abutment splinting induced decrease of strain on buccolingual side of 2nd premolar. The strain of loaded area was decreased by abutment splinting and there was no statistical difference of strain between Group2 and Group 3, and strain on 2nd premolar in wrought wire clasp was the least. Conclusion: Within the limitations of this study, splinting of two distal abutment teeth is enough for stress distribution widely, and wrought wire clasp was more benefitable than others.

• Food Science and Biotechnology
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• v.16 no.6
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• pp.967-974
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• 2007

The present work is aimed to evaluate the protective effect of glutathione-enriched Saccharomyces cerevisiae FF-8 strain on carbon tetrachloride ($CCl_4$)-induced hepatotoxicity and oxidative stress in rats. The activities of liver markers (alanine aminotransferase, aspartate aminotransferase, alkaline phosphatase, lactate dehydrogenase), lipid peroxidative index (thiobarbituric acid-reactive substances), and the antioxidant status (reduced glutathione) were used to monitor those protective roles of FF-8 strain. The liver marker enzymes in plasma and the lipid peroxidation in the liver were increased when $CCl_4$ was treated but these were significantly decreased by FF-8 strain treatment. The hepatic concentration of glutathione in the current glutathione-enriched FF-8 strain fed animal was approximately twice as high as the normal, but this was slightly increased in response to $CCl_4$ plus glutathione-enriched FF-8 strain. The increased liver triglyceride concentration due to the $CCl_4$ treatment was significantly decreased by FF-8 strain and the reduced level reached to that of normal group. Administration of FF-8 strain in normal rat did not show any signs of harmful effects. Therefore, the current findings suggest that FF-8 strain could be an effective antioxidant with no or negligible side-effects and it might be useful for the purpose of protection treatment of hepatotoxicity and oxidative stress in $CCl_4$-treatment in rat.

• Transactions of Materials Processing
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• v.11 no.8
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• pp.682-690
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• 2002

The formation of adiabatic shearband in tungsten heavy alloys(WHA) was studied in this investigation. Five prismatic specimens were loaded by high velocity impacts and treated as plane strain problems. To find out the effect of particle's volume ratio, specimens containing 81%, 93% and 97% volume percents of tungsten particles were used. Also the effects of particle's geometry and size on the formation of shearband were studied for 81% volume percent alloys by small size particle model, large size particle model and undulated particle models, and the results were discussed.be used to diagnose the causes of necking and fracture in industrial practice and to investigate whether these defects were caused by material property variation, changes in lubrication, or incorrect press settings. In non-axisymmetric deep drawing, three modes of forming regimes are found: draw, stretch, plane strain. The stretch mode for non-axisymmetric deep drawing could be defined when the major and minor strains are positive. The draw mode could be defined when the major strain is positive and minor strain is negative, and plane strain mode could be defined when the major strain is positive and minor strain is zero. Through experiments the draw mode was shown on the wall and flange are one of a drawn cup, while the plane strain and the stretch mode were on the punch head and the punch corner area respectively, We observed that the punch load of elliptical deep drawing was decreased according to increase of die corner radius and the thickness deformation of minor side was more large than major side.

• Journal of the Korean Society of Combustion
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• v.13 no.4
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• pp.26-36
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• 2008

Experimental study is conducted to identify the existence of a shrinking flame disk and to clarify its flame characteristics through the inspection of critical mole fraction at flame extinction and edge flame oscillation at low strain rate flames. Experiments are made as varying global strain rate, velocity ratio, and burner distance. The transition from a shrinking flame disk to a flame hole is verified through gradient measurements of maximum flame temperature. The evidence of edge flame oscillation in flame disk is also provided through numerical simulation in microgravity. It is found at low strain rate flame disks in normal gravity that buoyancy effects are importantly contributing to lateral heat loss to burner rim, and is proven through critical mole fraction at flame extinction, edge flame oscillation, and measurements of flame temperature gradient along flame disk surface.