• Proceedings of the KSME Conference
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• 2007.05a
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• pp.1684-1689
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• 2007

Fretting wear is one of the important degradation mechanisms of steam generator tubes in the nuclear power plants. Especially, impact fretting wear occurred between steam generator tubes and tube support plates or anti-vibration bar. Various tests have been carried out to investigate the wear mechanisms and to report the wear coefficients. Those are fruitful to get insight for the wear damage of steam generator tubes; however, most wear researches have concentrated on sliding wear of the steam generator tubes, which may not represent the wear loading modes in real plants. In the present work, impact fretting tests of steam generator tube were carried out. A wear progression model for impact-fretting wear has been investigated and proposed. The proposed wear progression model of impact-fretting wear is as follows; oxide film breaking step at the initial stage, and layer formation step, energy accumulation step and finally particle torn out step which is followed by layer formation in the stable impact-fretting progress. The wear coefficient according to the work-rate model has been also compared with one between tube and support.

• Ocean and Polar Research
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• v.36 no.4
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• pp.455-463
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• 2014

This paper presents data from performance tests carried out to assess a manganese nodule crusher. Manganese nodules should be crushed into smaller pieces in order to assure the slurry flow of the lifting system. Both artificial nodules and real manganese nodules are used to evaluate nodule breaking ability of the crusher. The crushing performance of the crusher depends on the flow rate and pressure of the power transmission device. The size of the crushed manganese nodules also depends on the shape of the crushing drum. In this paper, several comparative tests are carried out to evaluate and improve the crushing performance and find the optimal design point of the crusher.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.25 no.10
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• pp.59-66
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• 2011

In electric power system, the circuit breaker is not operated when the higher voltage then the rated TRV(transient Recovery Voltage) appeared in the circuit breaking, The TRV of a circuit breaker means the characteristics of reignition by the arc between two poles. and is decided by the value of connecting Impedance. In this paper we of carried out many kinds of experiments varying the types of bus, the types of installation, the length of installation between 22.9 [kV] level circuit breaker and MTR in general 154/22.9[kV] system, We also simulated the characteristics of TRV using EMTP-RV program. The suitability of TRV in assessed by Uc, RRRV(Rate of Rise of Recovery Voltage) which are defined by the international guide, IEC62271-100. The values of RRRV gained from the cable-made bus are 590[%] lesser than those from the NSPB-made bus respectively. So the triangled type is more rational in the aspect of TRV.

• The Transactions of the Korean Institute of Electrical Engineers C
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• v.54 no.4
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• pp.149-153
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• 2005

We have investigated thermal properties showed by changing the content of carbon black which is the component parts of semiconductive shield in underground power transmission cable. Specimens were made of sheet with the nine of those for measurement. Heat capacity (${\Delta}$H), glass transition temperature (Tg) and melting temperature (Tm) were measured by DSC (Differential Scanning Calorimetry). The ranges of measurement temperature were from -100($^{\circ}C$) to 100($^{\circ}C$), and heating rate was 4($^{\circ}C$/min). And then thermal diffusivity was measured by LFA 447. The dimension of measurement temperature was 25[$^{\circ}C$]. Glass transition temperature of specimens was showed near -25[$^{\circ}C$] and the heat capacity and the melting temperature from the DSC results were simultaneously decreased according to increasing the content of carbon black, while thermal diffusivity was increased according to increasing the content of carbon black. Because ionic impurities of carbon black having Fe, Co, Mn, Al and Zn are rapidly passed kinetic energy increasing the number of times breaking during the unit time with the near particles according to increasing vibration of particles by the applied heat energy.

• Proceedings of the KIEE Conference
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• 1993.11a
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• pp.32-34
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• 1993

In Korea, the low voltage secondary distribution method comprises lots of the maintainable and conservative problems. So, this paper deals with the plans to solve and decide the unification of the low voltage secondary. That is ; for the unification plan of the low voltage secondary must be previously solved the breaking of netural line in $3{\phi}4W$, $1{\phi}3W$ and enacted the flicker criteria in distribution power system. To decide the low voltage secondary should take into considersion by economics, security and future. The flicker fluctuation in the low voltage secondary 7.4% in responsibility limited place and under 10% in Arc welding. To prevent the netural line in $3{\phi}4W$, $1{\phi}3W$ must be thoroughly constructructed, joined the two sleeves.

• Journal of the Korean Society of Costume
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• v.52 no.2
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• pp.19-30
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• 2002

This is the research of Abject Art which was originated aesthetically in Abjection Theory of Julia Kristeva, a french psycho-analyst who argued liberational discussions about feminine identity against patricentric ideology which had fastened existing beautiful and elegant oedipal-feminine image and femininity as the secondary sex or the other's sex. and which became known by the planning display at whitney Museum of American in 1993. In Julia Kristeva's Abjection Theory which was written in her book(Power of Horror : An Assay on Abjection, 1992), she named pre-oedipal stage in which there is no sexual difference and has the same significance to both sexes instead of the oedipal stage which is becoming male-supreme reality as the semiotic and reinterpreted that an infant disregards feminine body--mother's body (Julia Kristeva, named it as Chora) as the love and the pain which carries her baby in herself and creates the baby which belonged to herself--which belongs to the semiotic to enter the symbolic smoothly. So the Abjection art is partly consist of some works which express the concertion of the boundary rebated with infant Identity which is not yet the other perfectly nor the subject perfectly, and of some works called Excretory Arts which express the excretion and vomiting which is the original experience of the abject. I expect that this research can be the chance of breaking from the fastened identity which was granted on female and feminine costume in this masculine-view centric society and creating the new position of costume and dress in the field of art by analyzing the costumes especially among these works.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.32 no.10
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• pp.817-822
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• 2008

Fretting wear is one of the important degradation mechanisms of steam generator tubes in the nuclear power plants. Especially, impact fretting wear occurred between steam generator tubes and tube support plates or anti-vibration bar. Various tests have been carried out to investigate the wear mechanisms and to report the wear coefficients. Those are fruitful to get insight for the wear damage of steam generator tubes; however, most wear researches have concentrated on sliding wear of the steam generator tubes, which may not represent the wear loading modes in real plants. In the present work, impact fretting tests of steam generator tube were carried out. A wear progress model for impact-fretting wear has been investigated and proposed. The proposed wear progress model of impact-fretting wear is as follows; oxide film breaking step at the initial stage, and layer formation step, energy accumulation step and finally particle torn out step which is followed by layer formation in the stable impact-fretting progress. The wear coefficient according to the work-rate model has been also compared with one between tube and support.

• Health Policy and Management
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• v.6 no.2
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• pp.131-148
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• 1996

This study was carried out by using questionnaires with 200 general doctors serving as the director of health subcenter in Kyongsangbuk-do Province as of January 1995. The results are summarized as follows. It was shown that the general characteristics consisted of 53 directors in the lst year(26.5%), 85 in the 2nd year(42.5%) and 62 in the 3rd year(31.0%). The percentage spent on their medical service showed that 73.0% of those directors spent more than 90% on their medical service. Based on their general service attitiude, 0% answered that the director of the health subcenter completes the given duties as the director, and 24.5% did that the director has the sense of responsibility and duty. Multiple answers concerning inconvenience and difficulties of the health subcenter director showed that less monthly salary accounted for 75.5%, no administrative power for 50.0%, insufficient medical instruments for 35.5%, insufficient budget for 30.0%, respect. In conclusion, in order for the health subcenter to meet the function as the primary medical clinic, it is required to arange the plans to inspire the public health doctors' service desire to that they can give the medical service as good as the private primary medical clinics, to convert existing concept of the public health doctors' placement in Myon administrative district into new concept in Gun by breaking from a uniform placement, and to consider an intensive placement according to the relevant projects so that preventive health activities can be planned and carried out.

• Proceedings of the Korean Vacuum Society Conference
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• 2011.02a
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• pp.257-257
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• 2011

The amorphous indium-gallium-zinc-oxide (a-IGZO) materials for use in high performance display research fields are strongly investigated due to its good performance, such as high mobility and better transparency. However, the stability of a-IGZO materials is increasingly becoming one of critical issues due to the sub-gap electron trap sites induced by rough interfaces during deposition processing. It is well-known that the threshold voltage shift is related to interface roughness and oxygen vacancy formed by breaking weak chemical bonds. Here, we report the better properties of transparent oxide transistors by reducing the threshold voltage shift with an external rf plasma supported magnetron sputtering system. Mainly, our sputtering method causes the surface of sample to be sleek, so that it prevents the formation of various defects, such as shallow electron trap sites in the interface. External rf power was applied from 0 to 50W during RF sputtering process to enhance the stability of our oxide transistor without having a large voltage shift. To observe the effects of external rf-plasma source on the properties of our devices, Scanning Electron Microscopy (SEM), Atomic Force Microscopy (AFM), Transmission Electron Microscopy (TEM) are carried out to observe surface roughness and morphology of sputtered thin film. In addition, typical electrical properties, such as I-V characteristics are analyzed.

• Proceedings of the KIEE Conference
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• 2001.11b
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• pp.340-343
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• 2001

In an electrical network, electrical power are transmitted by a various of protection, isolation and control electric circuit devices. This thesis deals with the protection function between circuit-breakers. The protective coordination concerns the behaviour of two devices placed in series in an electrical network, with a short-circuit downstream circuit-breaker. It has two basic principles: First, discrimination which is an increasing requirement of low voltage electrical distribution systems. Second, which is less well known: cascading, which consists of installing a device, whose breaking capacity is less than the three-phase short-circuit current at its terminals and helped by main circuit-breaker. The important advantage of cascading is to be able to install at a branch circuit-breaker of a lesser performance without endangering the safety of the installation for more economical usage. To determine and guarantee co-ordination between two circuit breakers, it is necessary to carry out a theoretical approach, first, and then confirm the results by means of standard tests. This is illustrated in appendix A of IEC 947-2.