• Restorative Dentistry and Endodontics
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• 제43권3호
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• pp.30.1-30.12
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• 2018

Objectives: To evaluate sealing ability of root canals obturated with bioceramic-impregnated gutta percha cone (BCC) or gutta percha (GP), with bioceramic sealer (BCS) or AH Plus (AH; Dentsply-Maillefer), in roundly-prepared canals using matched single-cone technique, based on bacterial leakage test, and to analyze obturation quality using micro-computed tomography (CT) analysis. Materials and Methods: Ninety-two distobuccal roots of maxillary molars were prepared using nickel-titanium files to apical size 40/0.06. The roots were divided into 4 groups (n = 20) that were obturated with a master cone and sealer: GP/AH, BCC/AH, GP/BCS, and BCC/BCS. Bacterial leakage model using Enterococcus faecalis was used to evaluate sealing ability for 60-day period. Obturated samples from each group (n = 4) were analyzed using micro-CT. Results: All groups showed bacterial leakage at 20%-45% of samples with mean leakage times of 42-52 days. There were no significant differences in bacterial leakage among the groups. Micro-CT showed minimal gaps and voids in all groups at less than 1%. Conclusions: In roundly-prepared canals, the single cone obturation with BCC/BCS was comparable to GP/AH for bacterial leakage at 60 days.

• 한국안전학회지
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• 제26권4호
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• pp.34-40
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• 2011

This paper is purposed to develop an leakage current detecting system(LCDS) which can prevent electrical fires on breaker capacity expansion as well as ruptures of XL(Extra long) pipelines and power failure by operation of ELB(Earth leakage breaker) at auto water machine in winter. In order to develop LCDS, this paper studied field state investigation, field state experiment, development of leakage alarm system and verification experiments. Field states investigation at livestock companies(10 companies) in cheong-won location to deduce the problems of auto water machine is analyzed. The field state experiment is conducted at B livestock company in cheong won location. The field state experiment method is measured with leakage current when ELB tripped by environment factor(fine, cloudy, and rainy day). The LCDS is developed as MCU(Micro Control Unit) part applied leakage current values at B livestock company. Verification experiments for the leakage current detecting system were conducted by two methods of current supply and field test. Results show that LCDS suggested in this paper are valuable and usable in auto water machine based on environment factor, which will prevent severe damage to human beings and properties and reduce the electrical fires in livestock.

• Tribology and Lubricants
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• 제18권4호
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• pp.273-278
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• 2002

Grease deterioration of mineral oil type grease was investigated using sealed deep groove ball bearings (6203) and bearing life test rig. The bearing test was performed under 3,000 rpm and 245 N radial load at 120。C. Grease taken ken tested bearings was checked in using certain evaluation methods, for example, oxidation induction time (OIT), FT-IR peak intensity, leakage .ate, bleeding .ate, total acid number. (TAN) and bearing noise increase. Within these test conditions, OIT, TAN, bleeding rate were changed gradually in accordance with bearing operating time and showed useful indices for deterioration of grease.

• 한국지하수토양환경학회:학술대회논문집
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• 한국지하수토양환경학회 2002년도 총회 및 춘계학술발표회
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• pp.221-224
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• 2002

To demonstrate prevention of the leachate leakage out of the landfill with creating inward hydraulic gradient, a tracer test and continuous waterlevel monitoring at the Inside and outside of the barrier wall of a costal landfill were peformed. When the tracers were injected into the well outside of the vertical wall system with high water level, then they were detected at the well inside of the system with low water level. Furthermore the lowered water level at the inside of the landfill than that at the outside prevented leachate leakage out of the landfill. This study reports results of the tracer test and waterlevel monitoring.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2003년도 춘계학술대회 논문집 유기절연재료 방전 플라즈마연구회
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• pp.6-10
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• 2003

In our country, the housing materials of polymeric outdoor insulators have mainly been used EPDM or silicone rubber. EPDM housing materials had been widely used in the field for the first time. The reason why silicone has the high cost of production. But recently, most of the manufacturers that newly developed polymeric insulators make its choice of silicone housing. EPDM showed a good resistance to tracking. We compared the various characteristics for EPDM and silicone insulators that have similar type and design. Silicone insulators have more performance in flashover voltage test and leakage current measurement because of a good water repellent than EPDM ones. Also, the property of EPDM compared with silicone insulators greatly decreased after aging test in combined acceleration ageing facilities for 1000 hours.

• 한국건축시공학회:학술대회논문집
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• 한국건축시공학회 2014년도 춘계 학술논문 발표대회
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• pp.234-235
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• 2014

Recently, waterproof construction used to self adhesive waterproofing sheet in the actual field in winter for reduce cost and term. However self adhesive waterproofing sheet's quality is declined in low temperature condition. So, this study was to confirm on the low temperature condition of concrete substrate effecting the adhesion of self adhesion waterproofing sheet using interface leakage test. As a result of this study, self adhesion waterproofing sheet must not be used at temperature below 5℃. Also, adhesion between waterproofing sheet and concrete is declined in low temperature.

• 대한기계학회논문집B
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• 제27권12호
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• pp.1655-1666
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• 2003

It is experimentally well-known that high anisotropies of the turbulent flow field are dominant inside the tip leakage vortex, which is attributable to a substantial proportion of the total loss and constitutes one of the dominant mechanisms of the noise generation. This anisotropic nature of turbulence invalidates the use of the conventional isotropic eddy viscosity turbulence models based on the Boussinesq assumption. In this study, to check whether an anisotropic turbulence model is superior to the isotropic ones or not, the results obtained from the steady-state Reynolds averaged Navier-Stokes simulations based on the RNG k-$\varepsilon$ model and the Reynolds stress model (RSM) are compared with experimental data for two test cases: a linear compressor cascade and a forward-swept axial-flow fan. Through this comparative study of turbulence models, it is clearly shown that the RSM, which can express the production term and body-force term induced by system rotation without introducing any modeling, should be used to predict quantitatively the complex tip leakage flow, especially in the rotating environment.

• 대한기계학회:학술대회논문집
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• 대한기계학회 2002년도 학술대회지
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• pp.619-622
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• 2002

It has been recognized that the flow in the blade passage of an axial turbomachinery rotor is very complex and is influenced by various flow phenomena, of which the tip leakage flow passing through the gap between rotor blade tip and casing plays a significant role. The losses produced due to the existence of the clearance have been known to be a large contributor of the rotor overall losses. Despite several experimental studies on non-rotating blade in the cascade configuration, and on actual rotating blades, the detailed nature of the complex flow phenomena associated with tip leakage, however, remains largely unresolved. Thus, a single-stage compressor test rig was built and measurements were taken at upstream and downstream of the rotor of this compressor at the aerodynamics laboratory of University of New South Wales. A five-hole probe and a hot-wire probe were used to measure mean and fluctuating flow parameters. The results show that tip leakage losses rise rapidly beyond tip gap of 0.01 Furthermore, the present project also identifies the regions in the wake behind the rotor of the axial compressor where such losses are concentrated. These results should be useful in the better design of rotors for improved performance of axial compressor.

• KIEAE Journal
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• 제13권3호
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• pp.79-89
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• 2013

The purpose of this study is to evaluate the airtightness performance of New Han-ok and to supply fundamental data for standards establishment. Air leakage testings were accomplished by means of blower door test in 26 bedrooms of 16 Han-oks located in Jeonnam happy villages. Followings are results. 1) Air change per hour at 50 Pa(ACH50) is located on 8.42~78.38. 2) No correlation between ACH50 and volumes, floor area, above grade surface area. 3) The more wood structural elements are exposed, attached spaces, wooden sliding and casement windows, the less airtightness performance. 4) An Airtightness with ACH50/20(NL, Normalized leakage) is located on 0.42~3.92 and building leakage class following F(4%), G(11%, sufficiently leaky, No need mechanical ventilation), H(4%, Need of cost-effective tightening), I(31%), J(50%) by a single-story house the normalized leakage of ASHRAE.

• Restorative Dentistry and Endodontics
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• 제23권1호
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• pp.288-295
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• 1998

The microleakage of direct-access Class 2 restorations was evaluated. Cavities were prepared at mesial and distal proximal enamel surfaces of 20 extracted human molars through buccal window. Prepared cavities were filled with Ketac-Fil, Ketac-Silver, and Fuji II LC, following manufacturer's instructions. 4 specimens of each restorations were made through sectioning 1/4 of bucco-lingual length mesio-distally after thermocycling between $5^{\circ}C$ and $60^{\circ}C$ and imerging 0.5% basic-fuchsin dye solution. Leakage at both occlusal and gingival margin of each specimen was scored 0 to 3 with stereomicroscope. The results were as follows: 1. At occlusal margin, leakage in Ketac-Fil group was more than Ketac-Silver and Fuji II LC group (ANOVA p<0.05) and there was no significant difference between Ketac-Silver and Fuji II LC group(p>0.05), and at gingival margin, there was no significant difference amang materials (p>0.05). 2. Occlusal margin leaked more than gingival margin in Ketac-Silver and Fuji II LC group (t-test p<0.05). 3. Leakage was different according to bucco-lingual location in Ketac-Fil and Fuji II LC group, and lingaul specimen exhibited more leakage(ANOVA p<0.05).