• Restorative Dentistry and Endodontics
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• v.21 no.1
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• pp.321-338
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• 1996

The purpose of this study was to evaluate the effect of moistening and air-drying of acid conditioned dentin and enamel on the marginal microleakage. In this study, Class V cavity were prepared on both buccal and lingual surface of sixty extracted human premolars with cementum margin. These specimens were randomly devided into three groups and three dentin adhesives(Scotchbond Multi-Purpose, All bond 2, Prisma Universal Bond 3) were applied to each group. The specimens in each group were subdevided into four groups (Wet/primed, Dry/primed, Wet/not primed, Dry/not primed) and the etched dentin and enamel surface were treated these four surface treatments prior to the placement of a bonding agent or adhesive. Wet/primed group was simply blot-dried with a damp facial tissue before primer placement ; Dry/primed group was air dried for 30 seconds before the placement of a primer ; Wet/not primed group and Dry/not primed group were not primed after blot dried and air dried for 30 seconds each group. The bonding agent and composite resin were applied for each group. All specimens were exposed to 500 cycle of thermal stress. Specimens were placed in a silver nitrate solution and then sectioned buccolingually through the center of the restoration. The dye penetrations of the specimens were observed with a stereo microscope. The statistical test were applied to the results using a one way analysis variance (ANOVA) and Duncan's multiple range test. The aspects of silver ion penetration into the resin/dentin interface were examined under scanning electron microscopy. The results were as follows. 1. In all groups, the enamel margin showed significantly lower leakage value than the cementum margin (p<0.05). 2. Regardless of various surface treatment and dentin adhesives, there was no significant difference at the enamel margins (p>0.05). 3. At the dentin margins, the leakage values of Dry/not primed group showed significantly higher than that of the other groups (p<0.05). The leakage values of Wet/primed group showed significantly lower than that of the other groups, but, there was no significant difference between Wet group and Dry group. 4. There was no significantly difference between the dentin adhesives regarding the surface treatments in all groups(p>0.05). 5. On the backscatterd scanning electron microscopy observation, the penetration of the silver ion occured at the bonding resin/dentin interface. In the Wet/primed group, resindentin hybrid zone and resin penetration into the dentin was observed. The resin tags were compactively formed to a thickness of $3\sim4{\mu}m$ at the upper part of dentinal tubules. In the Dry/primed group, the thickness of the hybrid zone and the diameter, depth of the resin tags diminished. In the Non-primed groups, the hybrid zone was not identified and few resin tag was observed. There was the gap formation in the resin/dentin interface.

• Economic and Environmental Geology
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• v.35 no.5
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• pp.407-420
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• 2002

The Buddhist Triad Cave in Gunwi (National treasure No. 109) consists of porphyritic biotite granite, and it has been deteriorated into microorganic smears, white films, brown rusts, granular decay, color changes, and joints by the same weathering factors as rain, moisture, temperature variation and microorganic living. Main origin is probably the rain that leaks into the cave along joints in Palgongsan granite, and then its moisture grows many microorganism and is frozen over during winter. The granites around the cave regularly develop two NEE and NWW joint sets that are conjugate to be a joint system. The NEE set extends far away with narrow joint spacings and affects the leakage of the rains, and is divided into 4 joint zones, among which J$_{m}$ and J$_{3}$ immediately affect the leaking water into the cave. An extensional Joint, in northern wall of the cave, was formed by toppling of the block between J$_{m}$and J$_{3}$joint zones from widening the Jm aperture by roots of a big pine tree, and passes through the J$_{m}$joint zone. This bypass allows no circulation of small rain, but a good circulation of heavy rain from influx to the cave for a long pathway. Many Joints and cracks, in the ceiling near the cave entrance, immediately get through the J$_3$ joint zone, and have a good circulation of small rain 10 mm. Both J$_{m}$and J$_{3}$ joint zones are, therefore, chief influxes that cause leakage of the rains.

• Korean Journal of Materials Research
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• v.14 no.1
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• pp.9-12
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• 2004

Metallic impurities, such as Fe, Cu, and Au, become generation and recombination centers for minority carriers when combined with oxide precipitates or silicon self-interstitial clusters. As these centers may cause leakage and discharge in silicon devices, their prevention through gettering of the metallic impurities is an important issue. In this article, key aspects of intrinsic gettering, such as oxygen control, wafer cleaning, device area denudation, and bulk oxygen precipitation are discussed, and a practical method of implementing intrinsic gettering is outlined.

• Fire Science and Engineering
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• v.34 no.4
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• pp.96-100
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• 2020

The leakage of hazardous materials due to the defect in storage tank foundations is likely to cause tremendous fire disasters in the industry cluster area. Thus, adequate design and construction of the tank foundation is required for preventing tank leakage. In this study, four types of typical tank foundations were classified and modeled for 3D FEM analysis to perform stability evaluation on tank foundations. Furthermore, numerical analysis indicated that stress concentration just below the tank shells is 40 times that at the tank center. The settlement influence zone is about the tank radius and tank diameter in the horizontal and vertical directions, respectively. Thus, the appropriate guidelines for the design and construction of tank foundations were suggested via a comparison assessment of the numerical analysis results on the stress distribution and displacement of the tank foundations.

• Journal of Advanced Marine Engineering and Technology
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• v.37 no.8
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• pp.877-885
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• 2013

A seawater pipe of the engine room in the ships is being surrounded with severely corrosive environments caused by fast flowing of the seawater, containing aggressive chloride ion and high conductivity etc.. Therefore, the leakage of the seawater from its pipe have been often occurred due to its local corrosion by aggressive chloride ions. Subsequently, its leakage area is usually welded by AC shielded metal arc welding with various electrodes. In this study, when the sea water pipe is welded with several types of electrodes such as E4301, E4311, E4313 and E4316, a difference of the corrosion resistance on the welding metal zones was investigated using an electrochemical method, observing microstructure, measuring polarization behaviors and hardness. The weld metal zone welded with E4313 electrode exhibited the lowest value of hardness compared to other weld metal zones. In addition, its zone indicated also the best corrosion resistance than those of other weld metal zones. Furthermore, all of the weld metal zones revealed a relatively better corrosion resistance than those of the base metal zones. and also showed higher hardness than the base metal zones.

• Journal of the Korean Institute of Gas
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• v.5 no.4 s.16
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• pp.85-91
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• 2001

This paper presents safety analysis of LNG leakage in a prestressed concrete outer tank, which is strongly related on the leak checking effects of the PC structure with and without a residual compression zone based on the BS 7777 codes. The full containment type outer tank which is constructed by a prestressed concrete may be destroyed by leaked cryogenic fluids. The FE calculated results show that the total leak checking time of the PC structure with $10\%$ residual compression zone is about 9 days for $-162^{\circ}C$ liquids. But, three primary pumps in an inner tank may operate to send cryogenic fluids for 6 days, which are stored in an inner tank of $140,000m^3$ capacity This means that the prestressed concrete outer tank may be safe for $-162^{\circ}C$ cryogenic fluids leaked from the demolished inner tank.

• Journal of Korean Society of Rural Planning
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• v.23 no.2
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• pp.87-96
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• 2017

This study is a basic research with the aim of developing the method of judging the leakage zone by grasping the habitat characteristic of agricultural reservoir slope in inhabiting characteristics appear differently according to natural inhabiting environment. To this end, this study is intending to investigate slope vegetation using a quadrat technique at Sinheung reservoir located at Gwangsi-myeon, Yesan-gun, Chungnam, and to perform the analysis of importance value using relative frequency and relative coverage, etc. Also, this study intended to present the necessity of having to consider the eco-system of the relevant region in time of a reservoir slope afforestation for the time to come by suggesting that the reservoir slope vegetation after a stable period becomes similar to the regional vegetation by comparing this study result with the existing research which carried out the analysis of importance value of forest vegetation for Yesan Region. The reservoir slope vegetation is similar to the indicator species which appear in the regional forest vegetation, so there was a need to select afforestation species in the light of this in time of slope afforestation. As a result of the analysis of the importance value, this study grasped that there was an emergence characteristic similar to the vegetation at a birthplace of a forest fires because growth and development of forest trees, and perennial plants were restricted by annually implemented brush-cutting work, etc.; however, indigo plant and bush clover, etc. were found to show the characteristic differing from this. Consequently, this study was able to confirm that there is the necessity of having to create the Importance Value Table suited for reservoir slopes by region through a lot more data construction in the near future.

• Journal of the Korea Safety Management & Science
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• v.12 no.4
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• pp.73-80
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• 2010

The purpose of this study was to investigate the actual conditions of radiation safety supervision in animal clinics using inspection standard of X-ray generator for diagnosis. The surveys for inspection standard system, equipment condition, and safety supervision were carried out in 18 animal clinics randomly. The inspection standard included reproducibility of dose exposure, kVp, mAs, collimator accuracy test, collimator luminance test, X-ray view box luminance test, grounding system equipment test and external leakage current test. The surveys of equipment condition and safety supervision used one-on-one interview with 5 points measurement. As a result, 44.44% of reproducibility of dose exposure was proper, 81.25% of kVp test was good, and 100% of mAs test was appropriate. Also, 66.66% of collimator accuracy test was proper, 61.11% of collimator luminance test was good, 53.13% of X-ray view box luminance test was suitable. In addition, only 5.55% of grounding system equipment and ground resistance was proper, 63.64% of external leakage current test was appropriate in grounding system equipment test. The 100mA electric capacity of X-ray generator for diagnosis was popular with 44.44%, and its 55.56% was purchased used equipment. Monthly average of less than 50 times (61.11%) was top frequency in use, and no animal clinic had a thermo-luminescence dosimeter(TLD). The 16 animal clinics with radiation safety zone and 2 without radiation safety zone were appeared.

• Journal of Radiation Protection and Research
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• v.28 no.2
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• pp.87-95
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• 2003

The fabrication process and the structure of PIN semiconductor detectors have been designed optimally by simulation for doping concentration and width of p+ layer, impurities re-contribution due to annealing and the current distribution due to guard ring at the sliced edges. The characteristics to radiation response has been also simulated in terms of Monte Carlo Method. The device has been fabricated on n type, $400\;{\Omega}cm$, orientation <100>, Floating-Zone silicon wafer using the simulation results. The leakage current density of $0.7nA/cm^2/100{\mu}m$ is achieved by this process. The good linearity of radiation response to Cs-137 was kept within the exposure ranges between 5 mR/h and 25 R/h. This proposed process could be applied for fabricating a PIN semiconductor detector for measuring individual dose.

• Corrosion Science and Technology
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• v.4 no.4
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• pp.140-146
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• 2005

Fossil fired power plant produces the electric energy by using a thermal energy by the combustion of fossil fuels as like oil, gas and coal. The exhausted flue gas by the combustion of oil etc. contains usually many contaminated species, and especially sulfur-content has been controlled strictly and then FGD (Flue Gas Desulfurization) facility should be installed in every fossil fired power plant. To minimize the content of contaminations in final exhaust gas, high corrosive environment including sulfuric acid (it was formed during the process which $SO_2$ gas combined with $Mg(OH)_2$ solution) can be formed in cooling zone of FGD facility and severe corrosion damage is reported in this zone. These conditions are formed when duct materials are immersed in fluid that flows on the duct floors or when exhausted gas is condensed into thin layered medium and contacts with materials of the duct walls and roofs. These environments make troublesome corrosion and air pollution problems that are occurred from the leakage of those ducts. The frequent shut down and repairing works of the FGD systems also demand costs and low efficiencies of those facilities. In general, high corrosion resistant materials have been used to solve this problem. However, corrosion problems have severely occurred in a cooling zone even though high corrosion resistant materials were used. In this work, a new technology has been proposed to solve the corrosion problem in the cooling zone of FGD facility. This electrochemical protection system contains cathodic protection method and protection by coating film, and remote monitoring-control system.