• Journal of the Korea institute for structural maintenance and inspection
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• v.3 no.3
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• pp.261-268
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• 1999

The seismic performance of precast concrete panel structures tested previously has been evaluated in this paper. Hysteretic curves of test specimens are idealized to elasto-plastic curves to get reliable yielding and ultimate displacements. For the idealized curves, ductility and energy dissipation capacity of specimens have been evaluated using a few guide lines. In addition, the strength capacity of specimens is checked for the strength demand caused by the design earthquake load including overturning moment effects. The result shows while the strength of specimen with joint box for vertical continuity is little bit lower than that of specimen connected by welding, the ductility of the former is higher than that of the latter. The energy dissipation ratios of PC specimens are ranged from 83% to 96% of that of Re specimen and the average of those are shown 90%.

• The Transactions of the Korean Institute of Electrical Engineers
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• v.37 no.6
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• pp.339-349
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• 1988

The simplified simulation technique for the best generation mix is developed and the studied results are described. The best generation mix over study time from the economic point of view can be easily constructed by this technique. Generator maintenance, the operation of pumpgenerator and LNG thermal generator with limited energy are simulated variously, so a role of each generator is also easily evaluated. Through parametric analysis, useful planning guide points are obtained for the best generation mix transition, nuclear power plant construction cost, ruanium cost , oil cost, coal cost and midnight factor in the study case corresponding to real power system size model.

• Proceedings of the KSR Conference
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• 2005.11a
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• pp.748-753
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• 2005

The stray current(leakage current) in DC railway system like as Metro Subway and LRT system happens electrical corrosion on theses superstructure facilities and also underground facilities that causes the public property losses. we must study and establish on the theoretical concept and concrete phenomena for electrical corrosion, In the construction period we intend to review and find out a lot of solution to minimize theses losses. we must investigate, measure and analysis natural atmosphere of these facilities locations to present a maintenance management guide for the upcoming operation stage.

• Proceedings of the Korean Nuclear Society Conference
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• 2005.10a
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• pp.1041-1042
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• 2005

• Proceedings of the Korean Institute of Building Construction Conference
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• 2005.11a
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• pp.141-148
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• 2005

This study as a demand of reconstruction allows the longevity of the multi complex, analyze the problems and solutions for a long term maintenance planning scheme, and how to save contingency fund to utilize. The major role of the multi complex housing market reflects Positively on our valuable society, provides a better life of environment on top of longevity and for the superior living duality. For a achievement and improvement existing long term maintenance Plan and contingency fund system should be considered as follows. First, shall be expanded more units of house as smaller group. Second, advice from expert shall be reconsidered, eliminated, and protected reorganizing an informal reconstruction planning comparatively legal procedure must be renegotiated and pursued. Third, the fund which saved for the contingency has to clarified as tax free item by government. It's not only mistreated as a limitation of personal asset but also treated as national source Despite of rather compulsive and constructive method must be noticed by whoever owns for, more positive follows, promotion and directing must be able to guide its understanding and adherence of importance and inevitability.

• Smart Structures and Systems
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• v.5 no.4
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• pp.357-367
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• 2009

Structural Health Monitoring (SHM), particularly remote monitoring, is an emerging field with great potential to help infrastructure owners obtain more and up-to-date knowledge of their structures. The methodology could provide supplemental information to guide the frequency and extent of visual inspections, and the possible need for maintenance. The instrumentation for a SHM system needs to be developed with longevity and the objectives for the system in mind. Sensors need to be selected for reliability and durability, sited where they provide the maximum information for the objectives, and where they can be accessed and replaced should the need arise over the monitoring period. With the rapid changes now occurring with sensors and software, flexibility needs to be in place to allow the system to be upgraded over time. Damage detection needs to be considered in terms of the type of damage that needs to be detected, informing maintenance requirements, and how detection can be achieved. Current vibration analysis techniques appear not yet to have achieved the necessary sensitivity for that purpose. Societal factors will influence the design of a SHM system in terms of the sophistication of the instrumentation and methodology employed.

• Journal of Korean Medical classics
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• v.28 no.2
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• pp.61-66
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• 2015

Objectives : Through the analyze of formative factor of time sense and the vital movement temporal rhythm in Huang Di Nei Jing(黃帝內經). Methods : We find out the principle and methods of Chronomedicine and Health Preserving in Huang Di Nei Jing(黃帝內經), and this finding will direct the life nurturing for later generations. We find that time sense had been established in Huang Di Nei Jing(黃帝內經), which had yin-yang and five elements characteristic. Results : There have temporal rhythm of functions of zang-fu viscera, meridian and collateral, qi and blood. Based on the theory of correspondence between human body and natural environment, established principle of health maintenance about based on yin and yang, temporal rhythm of visceral qi. Conclusions : Established health maintenance methods based on time such as adjusting-spirit according to time, regular daily life, dietary regimen according to time, needling and moxibustion according to time. These methods will guide syndrome differentiation and therapeutic method and Medication which based on suitable time.

• Journal of Korean society of Dental Hygiene
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• v.15 no.2
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• pp.325-332
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• 2015

Objectives: The purpose of this study was to investigate tooth whitening maintenance efficacy of several dentifrices containing effective ingredients for tooth whitening. Methods: Hydroxyapatite specimens(HAPs) staining was done by using modified Stookey's methods. HAPs were treated with 2.9% hydrogen peroxide containing strip for whitening, and were shaken with several dentifrice slurry(dentifrice 1 : artificial saliva 2) for 30 minutes. The HAPs were finally dipped in staining solution for an hour. Shaking and dipping were repeated 4 times and lightness values were measured by colorimeter at each step. In clinical test, test 4 dentifrice and control dentifrice were evaluated by 21 subjects for 2 months after receiving institutional review board(IRB) approval. Organoleptic(vita shade guide) and instrumental(SHADEEYE-NCC) evaluation were performed for whiteness change of teeth. Statistical analysis was performed using repeated measures ANOVA, Tukey's post hoc test and ${\chi}^2$-test(p<0.05). Results: All dentifrices showed statistical significance in comparison with control dentifrice containing sodium fluoride and test 4 dentifrice containing sodium pyrophosphate, sodium metaphosphate, candelilla wax, and sodium fluoride showed statistical significance in comparison with other dentifrices by inhibiting staining in vitro(p<0.05). In clinical test, test 4 dentifrice showed better effects than control dentifrice in organoleptic and instrumental evaluation in tooth whitening maintenance efficacy(p<0.05). The awareness toward tooth whitening maintenance efficacy for 2 months use showed that test 4 dentifrice was much better than control dentifrice, but did not show statistically significant(p>0.05). Conclusions: Dentifrice containing sodium pyrophosphate, sodium metaphosphate, candelilla wax and sodium fluoride was more effective in keeping teeth white.

• Journal of Advanced Navigation Technology
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• v.24 no.3
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• pp.205-211
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• 2020

Wiring defect is a major concern for safe aircraft operations. However, troubleshooting process of a wiring defect is very difficult due to extensive and complex wiring system and installed location. Recently, time domain reflectometer (TDR) equipment that enables effective defected wiring troubleshooting has been introduced. Unfortunately, TDRs have not practically adopted by most of airlines' maintenance departments because the effectiveness and usefulness of TDRs have not been verified. This study was conducted to verify if TDRs can identify the location and type of defected aircraft wiring, and whether they can be applied for troubleshooting purposes. Experimental plan was established by using various wires and connections applied to actual aircraft and the observed results were compared with the TDR operation guide. The usability of the TDR in actual aircraft wiring defect detection may be acceptable as the experimental results showed similar results to the TDR operation guide.

• Transactions of the Korean Society of Mechanical Engineers A
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• v.37 no.6
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• pp.815-820
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• 2013

With the development of technology, there has been a considerable increase in the number of skyscrapers in the world. Accordingly, there are increasing requirements with regard to maintenance, such as cleaning, painting, and inspection. However, it is extremely dangerous to work on the walls of buildings, and falls from buildings have accounted for a large proportion of construction accidents. In particular, as the number of buildings with irregular shapes increases, the accident rate during maintenance work has increased each year, with most accidents leading to deaths. An alternative solution must be developed with the commercialization of automatic systems. In this study, fundamental research has been conducted for drafting and commercializing an automation tool with a built-in guide system that can perform cleaning.