• Proceedings of the Korean Institute of Electrical and Electronic Material Engineers Conference
• /
• 2006.06a
• /
• pp.265-266
• /
• 2006

Superconductor is developed for applications in high-power devices such as power-transmission cables, transformers, motor and generators. In such applications, HTS tapes are subjected to various kinds of stress or strain. In the fabrication of the devices, the critical current (Ic) of the high temperature superconductor degrades due to many reasons including the tension applied by bending, twist and thermal contraction. In particular manufactured HTS cable, we need pitch angle controls. This paper is analyzed that Ic characteristics is changed pitch angle of HTS tape. These results will amount the most important basis data in HTS cable.

• Proceedings of the PSK Conference
• /
• 2002.10a
• /
• pp.286.2-286.2
• /
• 2002

Oxidative stress and its consequent lipid peroxidation exert harmful effects, which have been currently involved in the generation of carbon tetrachloride(CC14)-induced fibrosis(cirrhosis). In this study, it was investigated whether dried extract of 田螺(Concha Cipangopaludinae: CC) is liver functional improvement, antioxidative and antifibrotic effect under the liver fibrotic(cirrhotic) condition by CC14 administration. The female Sprague-Dawley rats were divided into 3 groups(Normal, AC, AC-CC), and were observed for 3 weeks. (omitted)

• Journal of Life Science
• /
• v.19 no.7
• /
• pp.983-993
• /
• 2009

The effects of Monascus-fermented Korean red ginseng (MFRG) on the contents of serum lipids and tissues lipid peroxidation was investigated in alcohol feeding rats (AC group). Serum contents of total lipid and free fatty acid in alcohol feeding rats were significantly increased, but these increases tended to decrease in the AMFRG group. Serum triglyceride content was also significantly decreased in the AMFRG group compared to other groups. Serum content of total-cholesterol was significantly increased in AC group compared to normal control (NC) group, whereas there was no significant difference between the AC and AMFRG groups. Content of HDL-cholesterol in serum was slightly increased in the AC group compared to the NC group, but this increase in the AC group was more significantly increased in the AMFRG group. At the same time, atherogenic index (AI) was also significantly decreased in the AMFRG group compared to the AC group. Contents of thiobarbituric acid reactive substances (TBARS) in the liver, heart, spleen and testes were significantly increased in the AC group compared to the NC group, but these increases were significantly less in the AMFRG group. Contents of liver nonheme ion was increased in the AC group and was significantly decreased in the AMFRG group, which suggested that lipid peroxidation contents are inversely correlated with liver nonheme ion content. Hepatic glutathione concentration was significantly decreased in the AC group, but this content was significantly increased in the AMFRG group and it showed the antioxidant abilities of glutathione. These results suggested that Monascus-fermented Korea red ginseng has anti-atherogenic index (AI) effects as well as antioxidative activities through reduced tissue oxidative stress in alcohol feeding rats.

• Journal of Korean Academy of Nursing
• /
• v.23 no.2
• /
• pp.269-283
• /
• 1993

The purpose of this study was to develop a typology of stress in Nurses through the use of a Q methodology. The research was done between June, 1 and November 30,1992 Fifty nurse working in a hospital were interviewed to solicit statements on their opinions about concepts factors and coping methods related to stress. The statements which were collected were classified and categorized to a find list 48 statements. Each of the statements was written dr a separate card and 30 nurses were a shed to sort the co\ulcorner\ulcorner\ulcorner ac-cording the degree of agreement along with quasinormal distribution. The results of the sorting by each subject were coded and analyzed using the Quanal PC program. As a result of the analysis, four types were identified ; Type I was classified and named as ” neccessary for living Type II was named as ” stimulues to be avoided Type III was named as ” situation to be consumption. Type IV was named as ” self-limited problem which can be solve The correlation among each types was relatively high, but the characteristics of each type are unique and distinct. throughout this study, it was indentified that the type of Nurse’s stress would be formed.

• Speech Sciences
• /
• v.14 no.1
• /
• pp.21-35
• /
• 2007

This paper attempts to investigate phonetic substances of the stress patterns of English compounds and noun phrases, showing that the theoretically derived stress structures are not consistent with the accentual patterns in real utterances. Even though it has been long claimed that compounds have the stress pattern [1 3] and that noun phrases, [2 1] as in Chomsky & Halle (1968), their difference has not been yet explored empirically or phonetically. I present a phonetic experiment conducted to see if there is any difference along the tonal contours, mostly focusing on their pitch accent distribution. 36 different compounds and 36 different noun phrases included in carrier sentences were examined, and they were varied in position within a sentence. Results showed that various accentual patterns were produced, and among them, [H* X] predominantly occurs in all three positions in both compounds and noun phrases, whereas the patterns [X H*] and [X X] appear relatively more frequently in final position than in initial and medial position. Furthermore, the pattern [Ac + No], in which the preceding element is pitch-accented with no accent on the following one, is the major stress pattern in both compounds and noun phrases and in all three sentence positions. This suggests that there seems to be no difference in accentual patterns between compounds and noun phrases, which is not consistent with the hypothesis. The results are interpreted as saying that the preceding element alone tends to be prominent with no accent following it both in compounds and noun phrases, and that therefore, theoretically speculated phonological claims are not always phonetically supported.

• Journal of Korea Foundry Society
• /
• v.25 no.5
• /
• pp.209-215
• /
• 2005

The design of the Metal mold casting should consider several variables such as the material properties and shape of the mold. In particular, the thermal stress generated by the thermal expansion and contraction depending on the thermal gradient of the mold causes partial plastic deformation on the mold, which causes damage or fracture of the cast. Consequently, the thermal deformation along with thermal stress leads to thermal deformation of the cast itself. In this study, the temperature analysis of the cast and mold is simulated by FDM to control the thermal deformation and stress as a result of the thermal gradient of mold. Using the results from FDM simulation, the thermal deformation and stress are analyzed by FEM and, the optimal mold design with minimum thermal deformation of the cast is suggested.

• International Journal of Safety
• /
• v.1 no.1
• /
• pp.36-42
• /
• 2002

This paper is aimed at predicting the life of rubber insulating gloves under normal operating stresses from relatively rapid test performed at higher stresses. Specimens of rubber insulating gloves are subject to multiple stress conditions, i.e. combined electrical and thermal stresses. Two modes of electrical stress, step voltage stress and constant voltage stress are used in specimen aging. There are two types of test for electrical stress in this experiment: the one is Breakdown Voltage (BDV) test under step voltage stress and thermal stress and the other is lifetime test under constant voltage stress and temperature stress. The ac breakdown voltage defined as the break-down point of insulation that leakage current excesses a limit value, l0mA in this experiment, is determined. Because the very high variability of aging data requires the application of statistical model, Weibull distribution is used to represent the failure times as the straight line on Weibull probability paper. Weibull parameters are deter-mined by three statistical methods i.e. maximum likelihood method, graphical method and least squares method, which employ SAS package, Weibull probability paper and FORTRAN, respectively. Two chosen models for predicting the life under simultaneous electrical and thermal stresses are inverse power model and exponential model. And the constants of life equation for multistress aging are calculated using numerical method, such as Gauss Jordan method etc.. The completion of life equation enables to estimate the life at normal stress based on the data collected from accelerated aging test. Also the comparison of the calculated lifetimes between the inverse power model and the exponential model is carried out. And the lifetimes calculated by three statistical methods with lower voltage than test voltage are compared. The results obtained from the suggested experimental method are presented and discussed.

• International Journal of Highway Engineering
• /
• v.14 no.5
• /
• pp.31-45
• /
• 2012

PURPOSES: In Korea, rapid maintenance of distressed concrete pavement is required to prevent traffic jam of the highway. Asphalt concrete overlay has been used as a general maintenance method of construction for aged concrete pavement. AC overlay on existing concrete pavements experience various early distresses such as reflection crack, pothole and rutting, due to different physical characteristics between asphalt overlay and existing concrete pavement. Bonded concrete overlay(BCO) is a good alternative since it has advantages that can reduce various distresses during the service life since overlay material has similar properties with existing concrete pavements. Recently, BCO which uses the ultra rapid harding cement has been applied for maintenance of highway. BCO has advantage of structural performance since it does monolithic behave with existing pavement. Therefore, it is important to have a suitable bond strength criteria for securing performance of BCO. Bond strength criteria should be larger than normal tensile stress and horizontal shear stress occurred by traffic and environmental loading at bond interface. Normal tensile stress and horizontal shear stress need to estimated for the establishment of practical bond strength criteria. METHODS: This study aimed to estimate the bond stresses at the interface of BCO using the three dimensional finite element analysis. RESULTS: As a result of this study, major failure mode and maximum bond stress are evaluated through the analysis of normal tensile stress and horizontal shear stress for various traffic and environmental load conditions. CONCLUSIONS: It was known that normal tensile stresses are dominated by environmental loading, and, horizontal shear stresses are dominated by traffic loading. In addition, bond failure occurred by both of normal tensile stresses and horizontal shear stresses; however, normal tensile stresses are predominated over horizontal shear stresses.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
• /
• v.19 no.4
• /
• pp.71-78
• /
• 2005

This paper proposes a novel multi-level energy recovery sustaining driver for AC PDP(Plasma Display Panel), which solves the problems of the conventional multi-level sustaining driver. While the conventional circuit improves the voltage md current stress of the switching elements in Weber circuit not only there are parasitic resonant currents between resonant inductors and parasitic capacitance and hard switching, but also the changing period between 0 and sustain voltage is too long. Comparing the proposed circuit with the conventional circuit, the number of components are reduced and the parasitic resonant currents in resonant inductors are eliminated Moreover the hard switching problem is solved by using CIM(Current Injection Method) and the operating frequency will be high as much as possible by removing Vs/2 sustain period. And the circuit operations of the proposed circuit are analyzed for each mode and the validity is verified by the simulations using PSpice program.

• International Journal of Highway Engineering
• /
• v.6 no.2 s.20
• /
• pp.37-45
• /
• 2004

The asphalt concrete pavement takes various advantages of better riding quality, serviceability and easier maintenance. At the same time, it addresses a weak point of the premature failures due to rapid increasement of traffic volume, heavy vehicles and high temperature in summer. It increases the expenditure of maintenance and repair. In order to improve the performance of asphalt pavement avoiding this premature failure, the use reinforcements with geosynthetics have been considered. Geosynthetics are known as an effective reinforcement to restrain fatigue and reflective cracks in asphalt pavements. In this study, a comprehensive parametric study is conducted to capture the efficiency of geosynthetic-reinforcements using viscoelastic properties of the asphalt concrete(AC) layer. The investigated parameters were reinforcement location, AC layer thickness, temperature distribution across the AC layer and modulus of AC and base layer. As a result of observations, that reinforced asphalt concrete could be used effectively for improving resistance against fatigue cracks and permanent deformation. Especially, when a geogrid was placed at the interface between the asphaltic base and the subbase, tensile stress in the horizontal direction was significantly reduced.