• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.26 no.8
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• pp.102-106
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• 2012

This paper was carried out to survey fire hazard and improvement at the drain pump in air-conditioners. Based on the results of analysis, the proposal of electrical accidents prevention and a construction improvement are as follows. A power connection of the drain pump has two types, an electrical outlet type and direct connection type at control board of air-conditioner. The electrical outlet types need a bulletin sign or education as malfunction of the drain pump include an additional accidents, current leakage and overflowing with water on the floor from breaker trip by exterior cause and breaker off by mistake of worker. On the other hand, the direct connection types prevent a power interruption as exterior cause, but it has some trouble, cut of ground cable and without protection device. Usually it doesn't work by electrician when air-conditioner and the drain pump power work. Therefore an education or countermeasures are recommended for not electrician. Generally malfunction of the drain pump causes accumulated materials into the tank. Even though the accumulated materials lead to an overheating and burning as failure of detector occur an idling, periodic inspection of the air-conditioner filter and the drain pump tank prevent the trouble.

• Restorative Dentistry and Endodontics
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• v.24 no.3
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• pp.453-464
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• 1999

The non-vital bleaching technique has been used widely as a very effective treatment method on discolored non-vital teeth. But periodontal tissue deterioration and cervical external root resorption have been reported because of the high toxicity of hydrogen peroxide in bleaching agents. So in previous studies, placement of base over the root canal obturation prior to bleaching has been suggested in order to prevent microleakage of bleaching agents, however, the effectiveness of base is still controversial. The purpose of this study was to evaluate the effects of base and root canal sealer on prevention of leakage of bleaching agents in non-vital bleaching. Fifty-two extracted sound teeth with single root were used. For root canal obturation, Tubuli seal$^{(R)}$(Kerr Co., USA) was used in 39 teeth and in others, AH-26$^{(R)}$(De Trey Dentsply, Inc., Switzerland) was used as a root canal sealer. 26 teeth among the teeth obturated with Tubuli seal$^{(R)}$ were divided into two groups, and Dentin cement$^{(R)}$(GC corp., Japan) and JRM$^{(R)}$(De Trey Dentsply, Inc. Germany) were used in each group as a intracanal base. In all teeth, non-vital bleaching using bleaching agent mixed with methylene blue dye was performed and all specimens were stored in $37^{\circ}C$ water bath for 72 hours. After sectioning longitudinally, the depth of dye leakage was measured with digital vernier calipers under the stereobinocular microscope using ${\times}40$ magnification. It can be concluded as follows: 1. The microleakage of bleaching agent was observed ill all groups regardless of type of the base and the sealer. 2. The microleakage in the groups using AH-26$^{(R)}$ as a sealer was significantly reduced (p<0.05). 3. In the groups with intracanal base, micro leakage was observed through almost the whole depth of the base and there was no significant difference between Dentin cement$^{(R)}$ and IRM$^{(R)}$ group(p>0.05). In conclusion, all the basing materials and the sealers in this study did not prevent the microleakage of bleaching agent. Therefore further studies and attempts to seal off the pulp chamber will be necessary.

• Geomechanics and Engineering
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• v.33 no.3
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• pp.291-299
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• 2023

Monitoring contaminants in waste landfills on a seabed is important because the leachate affects the marine ecosystem and facility stability. The objective of this study is to optimize a time-domain reflectometry (TDR) probe using different coating materials and several electrodes to estimate contaminants in saline soil. Copper concentrations ranging from 0 mg/L to 10 mg/L were mixed in 3% salinity water to simulate contaminants in the ocean environment. Epoxy, top-coat, and varnish were used as coating materials, and two to seven electrodes were prepared to vary the number and arrangement of the electrodes. Test results showed that the varnish stably captured the increase in copper concentration, while the other coating materials became insensitive or caused leakage current. In addition, a TDR probe with more electrodes exhibited stable and distinct electromagnetic signals. Thus, the TDR probe with seven electrodes coated with varnish was effectively used to estimate contaminants in saline soil.

• The Journal of Korean Academy of Prosthodontics
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• v.38 no.5
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• pp.618-630
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• 2000

As Fiber-reinforced composite restorations cannot be made without leaving a marginal gap, luting cements play a pivotal role in sealing the margins as a prevention against margnal leakage. A recently introduced adhesive resin cement system is claimed to adhere chemically, as well as mechanically, to tooth substances, dental alloys and porcelain. But when considering the clinical variation conventional cementation using Zinc Phosphate and Glass-Ionomer can be requested. A vitro study was undertaken to compare microleakage and marginal fitness of Fiber-reinforced composite crowns(Targis/Vectris) depending upon luting cements. Fifty non-carious human premolar teeth were randomly divided into five experimental groups of 10 teeth each and luted with five luting cements. ($Bistite\;II^(R),\;Super-bond^(R),\;Variolink\;II^(R)$), Zinc phosphate and Glass-Ionomer cement) After 24 hours of being luted, all specimens were thermocycled 300 times through water bath of $5^{\circ}C\;and\;55^{\circ}C$ in each bath, then the quality of the marginal fitness was measured by the Digital Microscope and marginal leakage was characterized using Dye Penetration technique and the Digital Microscope The results were as follows : 1. The mean values of marginal fit were Bistite II($46.78{\mu}m$), Variolink II($56.25{\mu}m$), Super-Bond($56.78{\mu}m$), Glass-Ionomer($99.21{\mu}m$), Zinc Phosphate($109.49{\mu}m$) indicated a statistically significant difference at p<0.001. 2. The mean microleakage values of tooth-cement interface, restoration-cement interface were increased in the order of Variolink II, Bistite II, Super-Bond, Glass-Ionomer, Zinc Phosphate 3. Crowns luted with resin cement (Bistite II, Super-Bond, Variolink II, etc) exhibited less marginal gap and marginal leakage than those luted with conventional Glass-Ionomer and Zinc Phosphate cement. 4. The results indicated that all five luting systems yielded comparable and acceptable marginal fit.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.20 no.4
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• pp.78-85
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• 2006

A person's body resistance in the waterpark, public bath and similar places is much lower than any other places due to effect of water. So low voltage may create a shock hazard for the human body in case of leakage or fault currents from lighting unit etc. We researched the related regulations which are internal standards, NEC, IEC and investigated the actual conditions for the prevention of electric shock due to lighting units in the waterpark, public bath and similar places. As a results internal standard is obscure as compared with NEC, IEC which is the limit of application and distinction of environment condition. And then internal standard's using voltage is higher than NEC, IEC in filed of water. Studies show that internal standard should be revision that raise the installation height of lighting unit, mark IP level surface of lighting unit and limit using voltage to line-to-line voltage

• The Journal of Engineering Geology
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• v.19 no.4
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• pp.433-439
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• 2009

The compressed packer device is designed to improve the underground contamination prevention facilities of ground water wells. As for the device, the installation is simple because of the safety lock device and the compression of the casing are simple the installation is simple. There is no leakage of ground water because the pressure resistance with $4.5\;kg/cm^2$ makes it equipped with the watertightness The single casing is installed and the reaming for grouting is possible with 300 mm excavation so that installation cost can be saved. Silicon rubber is used for the compressed packer so that the extension rate is 590%. In terms of environmental pollution, it is an environmental friendly product which does not contain harmful ingredients such as Pb, Cd, and phenol. below the standard or undetectable level Furthermore, the installation costs are 35 to 62% or lower than the conventional grouting construction method and are 87% or lower than the expansion packer construction method, the new environmental technology No.47 Also, the device is designed to meet the relevant regulations such as Rules on Preserving the Ground Water Quality, The Standard on Jeju Island Ground Water Development and Facility Installation and Management, and The Plan and Guideline on Operating and Managing the Small-Scale Tap Water Facilities of Ministry of Environment and Ministry of Food, Agriculture, Forestry and Fisheries.

• Journal of the Korea Institute of Building Construction
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• v.10 no.3
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• pp.129-136
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• 2010

This study is an evaluation of the water-tightness properties of rain-block systems in the sliding-roof joint of large-span membrane structures. In this study, we suggested a method of evaluating the water-tightness performance of the joint part of a sliding door in the roof of a large-span membrane structure (for a pilot project), in an environment of rain and wind. The shape of the rainwater blocking systems of the joint part in a sliding door verifies the defects and the effects of water leakage prevention when there is precipitation with wind conditions. To secure the water-tightness of large span membrane structures, it is necessary to have a guideline on the evaluation of the design for rain-block system of the joint part, and the quality of the membrane material, both of a retractable roof and a closed roof.

• Korean Journal of Remote Sensing
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• v.37 no.3
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• pp.591-601
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• 2021

As the domestic chemical industry continues to develop, handling and transportation of chemicals increases every year. Road freight in Korea accounts for more than 90%, and most of the chemical transportation is done through roads. These chemical vehicles can lead to major accidents if accidents occur. Transportation vehicles are likely to cause water pollution and soil pollution, which are factors of environmental damage, as well as traffic accidents that are the primary damage. In this work, we write a scenario for hydrogen chloride gas leakage by setting Banpo IC and Seocho IC sections as research areas, and use the ALOHA program to measure the predicted distance and analyze the time when hydrogen chloride gas reached according to the distance. In addition, risk assessment using population density was carried out for areas of damage caused by time using GIS. This suggests the need for prevention and countermeasures in areas of damage.

• Journal of the Korean Geosynthetics Society
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• v.6 no.2
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• pp.9-15
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• 2007

Bedding zone in CRFD (Concrete Faced Rockfill Dam) requires bearing capacity to support the concrete face slab uniformly. Also, shear strength which is a key factor in slope stability and impermeability which is to prevent a loss of soils in case of leakage of concrete slab face are needed. In this study, trial prototype construction for bedding zone in CRFD was performed to investigate the compaction characteristics of bedding zone according to the frequency of compaction, water contents and so on. As a results of series of field test, the compaction characteristics of bedding zone in CRFD was affected considerably by the depth of compaction layer and frequency of compaction.

• Journal of Korean Society of Disaster and Security
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• v.10 no.1
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• pp.43-46
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• 2017

Recently, the development of underground space is being actively carried out in the urban area by saturation, and the excavation works are mainly carried out by various excavation methods by the structures adjacent to the ground and underground excavation. During such excavation work, ground subsidence accidents are occurring due to inattention construction, lack of construction technology, and leakage of ground water. For the prevention of ground subsidence we studied the method of risk influence factors by soil investigation. Analysis of 75 sites soil investigation by U.S.C.S (Unified Soil Classification System), construction method, depth of excavation and we studied the risk influence factors with ground subsidence.