• The Korean Journal of Food And Nutrition
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• v.30 no.6
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• pp.1299-1309
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• 2017

The aim of this study was to investigate status of safety accidents of school foodservice cooks in Daegu and to analyze the factors affecting the occurrence of the accidents in order to seek effective ways for preventing safety accidents in school foodservice. The survey showed that the most frequent safety accidents were 'bruises', followed by 'burns', 'contact with harmful substances such as disinfectants', 'fall-off ' and 'sprains'. The mental fatigue perception of the respondents was generally lower than the physical fatigue perception. The means of the perception levels of work intensity, cooking environment of the foodservice place, and safety-related behaviors, and consciousness were 3.15, 2.99, and 4.06 out of 5 points, respectively. In addition, the annual average of the number of participating in the accident prevention training per person was 17.34 times, that is, the respondents received the training at least once a month on average. A multiple regression analysis was conducted to investigate the variables affecting the occurrence of safety accidents that happened to foodservice cooks. It revealed that the work intensity perception and the cooking environment perception influenced the frequency of safety accidents.

• Journal of the Korean Society for Aeronautical & Space Sciences
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• v.35 no.10
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• pp.905-911
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• 2007

In this paper, geometrically and materially non-linear finite element analyses were performed to study the crease behavior of thin membranes. The cross-section of the membrane was modeled with 2-dimensional plane strain elements. To simulate the creasing process, the membrane mesh was folded, compressed to prescribed crease gauge by activating two rigid contact surfaces, and then released to give the crease topology. Various crease gauges were considered to investigate the effect of crease intensity on the initial deployment angle. The crease geometry was also obtained by experiments and the results were compared.

• Journal of Astronomy and Space Sciences
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• v.15 no.2
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• pp.335-340
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• 1998

We obtained UV light curves of 44i Bootis, a W UMa type star from the IUE low dispersion spectra. In order to investigate variations of the emission lines from chromospheric activity and transition region, UV line intensity has been measured for CI, CII, ClV, SiIV, HeII lines. Through plotting the line intensity with the orbital phase, we found that emission lines showed maximum at $0^p.2;and;0^p.8$ of the light curves, indicating the chromospheric activity of contact binary, 44i Bootis. We found that the light curves of UV emission lines is strongly modulated by the variation of chromospheric activities of 44i Bootis.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.11
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• pp.1737-1742
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• 2001

The fractal-based method for describing rubbed surface texture has aroused great interest. The determination of rubbed surface topography is believed to be extremely important in the areas of contact mechanics, adhesion and friction. In order to describe topography of the rubbed surface, the wear test was carried out with annular surfaces of wear testing specimens in dry friction. furthermore, the relation between the fractal dimensions and the frictional conditions are also investigated and fractal descriptors was applied to rubbed surface with image processing. Fractal dimension can be determined by sum of intensity difference of image surface pixel. Fractal dimension increased according as the applied load and sliding distance increase. Topography of the rubbed surface can be effectively obtained by fractal dimensions.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.20 no.10
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• pp.3126-3134
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• 1996

In this paper, to examine the propagation of inclined surface crack due to frictional heating, analytic model is considered as the semi-infinite elastic body subjected to the thermo-mechanical loading of an asperity moving with a high speed. Considering the moving of frictional heat source and convection on a semi-infinite surface having inclined crack, theoretical analysis was carried out to estimate the propagation characteristics of thermo-mechanical crack. Numerical results showed that stress intensity factor $K_\prod/P_0\sqrt{c}$ is increasing with increasing velocity and frictional coefficient, inclined degree, decreasing crack length and the maximum value of it is positioned at the trailing edge. So it is shown that the propagation probability of surface crack is high at the trailing edge of contact area as increasing velocity and frictional coefficient, inclined degree, as decreasing crack length.

• Structural Engineering and Mechanics
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• v.78 no.3
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• pp.333-350
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• 2021

Motivated by the demand of seismic protection of museum collections and development of performance-based seismic design guidelines, this paper investigates the seismic fragility of sliding artifacts based on incremental dynamic analysis and three-dimensional finite element model of the artifact-showcase-museum system considering nonlinear behavior of the structure and contact interfaces. Different intensity measures (IMs) for seismic fragility assessment of sliding artifacts are compared. The fragility curves of the sliding artifacts in both freestanding and restrained showcases placed on different floors of a four-story reinforced concrete frame structure are developed. The seismic sliding fragility of the artifacts within a real-world museum subjected to bi-directional horizontal ground motions is also assessed using the proposed IM and engineering demand parameter. Results show that the peak floor acceleration including only values initiating sliding is an efficient IM. Moreover, the sliding fragility estimate for the artifact in the restrained showcase increases as the floor level goes higher, while it may not be true in the freestanding showcase. Furthermore, the artifact is more prone to sliding failure in the restrained showcase than the freestanding showcase. In addition, the artifact has slightly worse sliding performance subjected to bi-directional motions than major-component motions.

• Maxillofacial Plastic and Reconstructive Surgery
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• v.34 no.3
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• pp.163-172
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• 2012

Purpose: Diabetes mellitus (DM) has been shown to alter the properties of the bone and impair bone healing around a titanium implant. The aim of this study is to investigate whether the low-intensity pulsed ultrasound (LIPUS), which has been known to stimulate the bone healing, improve the osseointegration of the titanium implant in tibia of DM-induced rats. Methods: 16 rats were received streptozotocin (60 mg/kg) for inducing diabetes. A total number of 32 titanium implants were placed bilaterally into both tibiae of these rats. The right tibia of each rat received LIPUS application (10 min/day) during 7 days post-operation, while the left side received no treatment. The study was carried on for six weeks and the rats were sacrificed at 1, 2, 4, and 6 weaks postoperatively (4 rats for each week) for histomorphometric and histologic analysis. Bone-implant contact and bone area were measured. Comparisons between the groups were made using statistical analysis on histomorphometric analysis. Results: The histomorphometry parameters showed that the bone-implant contact and the bone area values have decreased in the late osseointegration periods (4, 6 weeks) compared to the early osseointegration periods (1, 2 weeks) in both two groups. The bone-implant contact values of the LIPUS group were somewhat higher than those of controls at 1, 2 weeks, but the difference was not statistically significant. The bone area values of the LIPUS group were also higher than those of controls at 1, 2 weeks, but the difference was not statistically significant as well. Conclusion: Results of this study indicate that LIPUS may have positive effects on early osseointegration but could not improve the long term stability of dental implants.

• Journal of the Korean Society for Railway
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• v.13 no.1
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• pp.37-43
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• 2010

Catenary (Overhead Contact Lines) and Pantograph are used to transmit electrical energy to electric railways. An Arc occurs by unstable contact between catenary and pantograph during electric railways operation, which causes malfunctioning or even an accident. Therefore, to prevent a arc or electric contact loss are required arc detection systems with catenary maintenance capability. This paper describes developing of catenary arc detection system using photo detector in order to detect arc incidence in a indirect way. This developed system can also achieve Video-recordings and environmental conditions such as wire voltage/current, pantograph height, speed, position of electric railways, and temperature/humidity. This system have been evaluated at the section that bounds for dongdaegu from seoul. From the experimental results, the occurrence of arc and intensity of arc are mainly effected by wire voltage/current, pantograph height and speed of electric railways.

• Journal of the Korean Society for Nondestructive Testing
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• v.36 no.6
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• pp.466-473
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• 2016

In a shipbuilding process, thermal damage to the ship structure at the rear end results from an excessive heat input and conduction during welding process. To prevent such damage, appropriate control of the heat input, based on welding temperature measurement, is required. For temperature measurement, contact and non-contact methods are available; the thermography system is a popular non-contact temperature measurement. When the intensity of radiation from a high-temperature object is excessive, however, detecting the sensors of ordinary thermography systems leads to an inability in measuring the temperature due to saturation. Hence, this study suggests use of a neutral density filter that prevents an excessive amount of radiation from being accumulated in a thermography system, and thus makes it possible to quantitatively measure an object's temperature as high as $3000^{\circ}C$.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.25 no.9
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• pp.1400-1409
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• 2001

This paper describes a fiber optic sensor suitable for non-contact detection of ultrasonic waves. This sensor is based on a fiber optic Sagnac interferometer. Quadrature phase bias between two interfering laser beams in Sagnac loop is introduced by a polarization controller. A stable quadrature phase bias can be confirmed by observing the interferometer output versus phase bias. This method eliminates a digital signal processing for detection of ultrasonic waves using Sagnac interferometer. Interference intensity is affected by the frequency of ultrasonic waves and the time delay of Sagnac loop. Collimator is attached to the end of the probing fiber to focus the light beam onto the specimen surface and to collect the reflected light back into the fiber probe. Ultrasonic waves produced by conventional ultrasonic transducers are detected. This fiber optic sensor based on Sagnac interferometer is very effective for detection of small displacement with high frequency such as ultrasonic waves used in conventional non-destructive testing.