• Journal of the Korean Society for Heat Treatment
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• v.35 no.1
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• pp.20-26
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• 2022

This paper was designed to prevent intervertebral disc escape and treatment. we produced downsized lumbar traction bed at home and automated system depending on weight and muscle mass by using 3D print and Arduino to confirm the possibility of prototyping. Hence, we checked muscle mass 10 males in their 20s with different exercise conditions, and it shows that average muscle mass of group who exercised was 56.63kg, and non-exercise group was 50.8 kg. this is shows lumbar repetitive exercise can show the traction therapy effect can be seen traction therapy effect. In addition, we installed wooden doll substitute people with spring and test changing of length. Traction bed has the steps ranging from 1 to 4, in which the motor with torque and rpm, ranging from 4.7 to 5.5 kgf and from 4.5 to 5.3 rpm, respectively. The motor controlled with the voltage of Arduino was operated for the length of the spine to be stretched to 4-5 mm. As increasing the weight of the wooden doll by 10g, it was confirmed that the spring increased by 4-5 mm from the first step to the fourth step.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.1005-1011
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• 2007

The brake system of train must posses the large braking effort in order to stop the train safely within the limited traveling distance. But, the excessive braking effort has been deteriorated the ride comfort due to high level of deceleration and jerk, and sometimes occurred the skid, because the applied braking force exceeds the allowable adhesive force. This skid causes not only to increase the stopping distance but also to deteriorate the safety of train and damage the rail surface by wheel flat. In the present paper, the braking force for disc brake of Korea High Speed Train (HSR350x) was measured through on-line test and the adhesion force was estimated by using the analytic model in the skid condition. Also, we have discussed the relationship between the actual disc brake force and the adhesion force in real skid condition.

• Proceedings of the KSME Conference
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• 2001.06b
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• pp.630-634
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• 2001

Predicting brake squeal noise in design stage can be beneficial to reducing the expense of development. In this paper, the possibility of pre-estimating squeal phenomena of a disc brake system was investigated. To preestimate squeal phenomena, complex eigenvalue analysis was performed for brake system. The evaluation of noise dynamometer test verified the prediction and it corresponded with the result of complex eigenvalue analysis.

• Transactions of the Korean Society for Noise and Vibration Engineering
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• v.23 no.6
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• pp.485-494
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• 2013

This paper deals with experimental evaluation methods for high speed judder on the brake-caliper system. Firstly, two types of brake caliper systems due to the wheel vibration was evaluated. Secondly, the high-speed judder of the brake was also investigated using the subjective rating evaluation in the high-speed road test. These experimental evaluations were carried out by changing the materials of brake pad and the specifications of the brake-corner module. Based upon the test results, a new specification of the brake pad, $15{\times}5$ vertical chamfer, was proposed. The new brake pad showed 3 points, 60 %, improvement in the subjective-rating evaluation comparing with conventional one. Besides, we need to decide properly with judder characteristic of pad material and have to carefully take into consideration other design parameters; caliper, disc, and the braking performance, durability, squeal noise.

• Food Science of Animal Resources
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• v.31 no.2
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• pp.311-315
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• 2011

The objective of this study was to evaluate the antimicrobial effects of various natural flavonoids against growth of psychotropic Bacillus cereus strains, which cause dairy food outbreaks. Flavonoids were first screened for their ability to inhibit growth of B. cereus strains using the paper-disc diffusion test. Second, the growth inhibitory effect of selected flavonoids was evaluated in tryptic soy broth supplemented with 0.6% yeast extract, and the bactericidal effect of the flavonoids was measured in 0.8% (w/v) NaCl solution. Based on the paper-disc diffusion test, kaempferol was effectively active against B. cereus P14 and B. cereus KCCM 40935. Kaempferol had an antimicrobial effect at concentrations greater than 100 ${\mu}M$, and the numbers of B. cereus P14 and B. cereus KCCM 40935 decreased by 3.55 and 1.5 log cycles, respectively. The cell numbers of B. cereus P14 and B. cereus KCCM 40935 treated with 50 ${\mu}M$ kaempferol were reduced by 4.18 and 2.84 log cycles during a 24 h incubation to test the bactericidal effect of kaempferol (p<0.05). The results indicate that kaempferol had the greatest antimicrobial effect among the psychotropic B. cereus strains and the natural flavonoids tested.

• Journal of the Korea institute for structural maintenance and inspection
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• v.26 no.6
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• pp.54-63
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• 2022

This paper is a study on the friction damper, which is one of the seismic reinforcement devices for structures. This study developed a damper by replacing the internal friction material with ultra high molecular weight polyethylene (UHMWPE), a type of composite material. In addition, this study applied a multi-friction method in which the internal structure where frictional force is generated is laminated in several layers. To verify the performance of the developed multi-friction damper, this study performed a characteristic analysis test for the basic physical properties, wear characteristics, and disc springs of the material. As a result of the wear test, the mass reduction rate of UHMWPE was 0.003%, which showed the best performance among the friction materials based on composite materials. Regarding the disc spring, this study secured the design basic data from the finite element analysis and experimental test results. Moreover, to confirm the quality stability of the developed multi-friction damper, this study performed an seismic load test on the damping device and the friction force change according to the torque value. The quality performance test result showed a linear frictional force change according to the torque value adjustment. As a result of the seismic load test, the allowable error of the friction damper was less than 15%, which is the standard required by the design standards, so it satisfies the requirements for seismic reinforcement devices.

• Natural Product Sciences
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• v.4 no.1
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• pp.32-37
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• 1998

The water extracts of oriental herbal medicines which have been clinically used to treat bacterial infections in Korea were screened for in vitro antibacterial activity by the paper disc assay method. Two Gram positive bacteria, Staphylococcus aureus SG511, Bacillus subtilis ATCC 6633 and two Gram negative bacteria, Escherichia coli 055, Pseudomonas aeruginosa 9027 were used as test organisms. Among 83 of the extracts tested, 25 were active against Staphylococcus aureus SG511, 9 were active against Bacillus subtilis ATCC 6633, while none showed inhibitory activity against Eschelichia coli 055 and Pseudomonas aeruginosa 9027. Among them, Hwangyonhaedoktang plus hwangyon, Chongwisan, and Ssangbaksan showed remarkably potent antibacterial activity.

• Proceedings of the KSME Conference
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• 2008.11a
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• pp.1326-1330
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• 2008

The failure mode of steel road wheels in a vehicle is cracks from ventilation hole through to contact plane on steel wheel's disc plate. But a number of cracks of Cornering Fatigue Limit Test is on contact plane near to wheel nut mounting area, even though it's satisfied with specified cycles. So this paper searches out causes to improve durability and reliability of C.F.T by uni-axial bending moment test. The verified cause is a "fretting" on contact area of steel wheel. In result, this paper suggests a solution to prevent a fretting by inserting a damping shim, 0.7mm between steel wheel contact areas. Therefore this paper makes it possible to move crack position of C.F.T in steel wheel from contact plane to vehicle's failure mode.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.44 no.3
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• pp.250-256
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• 2008

Generally the side plate materials of FRP ship are composed of glass fiber and unsaturated polyester resin composites(GFRP composites). In this study, the effect of applied load and sliding speed on friction and wear characteristics of these materials were investigated at ambient temperature by pin-on-disc friction test. The cumulative wear volume, friction coefficient and wear rate of these materials for SiC abrasive paper were determined experimentally. The cumulative wear volume showed a tendency to increase nonlinearly with increase of sliding distance and was dependent on applied load and sliding speed for these composites. The friction coefficient of GFRP composites was increased as applied load increased at same sliding speed in wear test. It was verified by SEM photograph of worn surface that major failure mechanisms were microfracture, deformation of resin, cutting and cracking.

• Proceedings of the Korean Society of Tribologists and Lubrication Engineers Conference
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• 1999.11a
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• pp.19-24
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• 1999

Understanding of wear mode and prediction of wear rate of parts in sliding contact are very important in field of meterial design relating with wear resistant. This paper has been undertaken to analyze the possibility of elucidation of wear mode and prediction of wear rate for annealed steel in sliding contact using the X-ray diffraction. The sliding wear test with various velocities using pin-on-disc machine and the X-ray diffraction test on the worn surface have been carried out. The results have been shown that the magnitude of residual stress and half-value breadth on the worn surface have a good correlation with wear mode. The difference between before and after test of half-value breadth on worn surface has been shown to be exponential relation with wear rate in the same wear mode.