• Journal of the Korea Safety Management & Science
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• v.23 no.4
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• pp.55-60
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• 2021

This study is to check waterproof by number of twists of fire hose and measure the first waterproof time to analyze the relationship between twists of fire hose and first waterproof time and waterproof by position of twists so as to suggest the efficient plan to prevent twists of fire hose. Ordinary fire hose did not make waterproof in case that position of twists was near the nozzle with twists 5 times or more, while anti-twist fire hose had no problem for waterproof only with delayed time. Like ordinary fire hose, anti-twist fire hose also showed the tendency to increase the waterproof time in proportion to the number of twists. In case that the position of twists was near waterproof port even with 10 times of twists in anti-twist fire hose, the first waterproof time was increase by 0.63 seconds on average without any problem for waterproof, which was somewhat faster than that in ordinary fire hose. With respect to the position of twists, waterproof of anti-twist fire hose was affected more as the number of twists was increased more near the nozzle rather than near the waterproof port, like ordinary fire hose. In summary, anti-twist fire hose equipped with anti-twist tool at the middle connection port and the nozzle showed a good waterproof performance with delayed waterproof time regardless of number of twists, as a solution for the twist problem of ordinary fire hose.

• Proceedings of the Korea Concrete Institute Conference
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• 2006.05b
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• pp.65-68
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• 2006

In this study, comparison of setting time, compressive strength, watertightness and durability of between reference mortar with mortar using waterproof admixtures based on natural inorganic minerals. Test results shows that waterproof admixtures does not change setting time of mortar, but strongly improve compressive strength, permeability, absorption and durability of mortar. Especially early strength of mortar increased about 40% of reference.

• Journal of the Korean Geotechnical Society
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• v.18 no.6
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• pp.43-59
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• 2002

In this study, database systems which were used to select the waterproof method according to leakage patterns of underground structures were built by performing pilot tests, reviewing literatures, and analysing the gathered data statistically. The database was built by using check lists which consisted of 5 major items and 73 subdivided items, and 26 major parameters according to 4 classified grades were determined on the base of survey which considered various in-situ conditions. The database of waterproof methods was comprised of 10 methods which were applied in Korea. From the database of waterproof methods, application ranges and design conditions of waterproof methods were suggested. From the results of study, database system consists of parameters selection database, waterproof method database, and design condition database. From the results of pilot tests, when the database of waterproof methods was applied to design stage, saving time and reducing mistakes for selecting waterproof method were gained. In addition, when the database of waterproof methods was applied to construction stage, effects such as evaluation of applicability of waterproof method, improvement of constructability and post management were expected.

• Fire Science and Engineering
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• v.17 no.1
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• pp.21-25
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• 2003

This experimental study shows the thermal characteristics of the fire fighter's waterproof clothing exposed to the radiation heat. From the test results, the surface temperature of the fire fighter's waterproof clothing exposed to the radiation with the passage of time sharply increased as the exposed-distance became closer. Also as the radiant heat flux increased, the surface temperature is higher and the time reaching steady state is sharply shorter. As the exposed-distance become more distant, the surface temperature of the fire fighter's waterproof clothing decreased and the difference of temperature between the front side and the back side of the clothing decreased as well. Besides, the radiant heat flux increased, the safety exposed-distance increased. Therefore it is necessary that fire fighter have to work keeping a fixed safe distance from the radiant heat source.

• Magazine of the Korea Concrete Institute
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• v.8 no.1
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• pp.138-144
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• 1996

At present, waterproof is absolutely needed to minimize the carbonation of bridge decks in Kor ea. In this research indoor experiments for penetrative waterproof admixture out of available methods are carried out to evaluate the resisting characteristics against natural arid artificial car bona ting conditions. The test results show that the optimal time of waterproof is 14 days after the concrete construc. tion but reconsideration is necessary for the application to high strength concrete because of the reduction in penetration of waterproof admixture. The results also show that the penetrat ive waterproof admixture has srrong resistance to the acid rain. However the waterproof capability of the admixture is not permanent especially under the natural exposure. Therefore the slab of a bridge should be paved with asphalt concrete. Other noticeable effects are the increase of heat and abrasion resistances from the use of the waterproof agents.

• Proceedings of the Korean Institute of Building Construction Conference
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• 2008.05a
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• pp.35-41
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• 2008

Qualitative enhancement of dwelling life has changing the recognition for the environment friendly wood which is being highlighted for its usage as an interior materials. This trend may prove the excellent performance of wood whose inherent characteristics has its comfortable, mild feeling of material, sound resistance and stabilities and the market of interior woods including floor, moulding and wooden panel as finishing interior materials is growing sustainably. However, since this materials is vulnerable to humidity and flame, waterproofing and flame retarding stability, an essential condition for interior materials, together with maintenance, are the main topics to be resolved. From the above-mentioned results, as a result of waterdrop contact angle, wood absorption volume and water content percentage test and the performance test of the processed materials after flame retardant, though there was some submerging time changes among types of woods for ensuring waterproofing performance improvement but as time passes, similar tendency was noticed to be formulated. As the submerging time is increased, so does the absorption volume and accordingly optimal level of range is judged to be drawn in order to ensure excellent performance, taking optimal economy into consideration. Therefore, it is considered that above-mentioned woods could be utilized for waterproof and flame retardant processed interior materials using uniform microwave and in order to put this technology into practical application, a research by way of diversified performance proving is required to be carried out.

• Journal of the Korean Society of Safety
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• v.28 no.4
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• pp.43-47
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• 2013

The purpose of this paper is to evaluate the performance of a Plug-In MCCB developed for rapid power supply restoration when the MCCB is installed in a power system and to verify its reliability. Since the developed 3 ${\Phi}$ 3 W Plug-In MCCB can be installed on and removed from a bus bar by one touch using a plug housed at the rear, it can be replaced in a short period of time. Therefore, it can quickly respond to the normalization of a power system. When the Plug-In MCCBB is installed on a bus bar, the resistance between each phase and plug was measured to be 0.46 $m{\Omega}$ in average. When the Plug-In MCCB is installed, the tension in the vertical direction was measured to be 112.78 N in average, which is greater than the tension of 50 N specified in the related regulation. The withstanding voltage tests performed 5 times repeatedly by applying 6 kV to the developed Plug-In MCCB for 60 seconds shows good withstanding voltage characteristics. In addition, both the general waterproof test using a water injection method and the insulation resistance analysis using a Mega meter showed good waterproof and insulation characteristics.

• Journal of Bio-Environment Control
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• v.25 no.4
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• pp.288-293
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• 2016

The study was performed to evaluate thermal insulation covering materials (TICMs) to protect peach trunks against freezing temperatures in winter season by investigating thermo-physical properties and practical thermal insulation effect of the TICMs which was made of white non-woven fabrics, yellow paper sheets, and waterproof fabric pads. Among the three TICMs, Waterproof fabric pad (double layer) possessed the best performance about thermal insulation rate and thermal resistance among three kinds of TICMs. Day thermal insulation effects of waterproof fabric pad, which prevent from temperature rise on the bark tissues of trunks during the day time, were $14.09^{\circ}C$. Night thermal insulation effects of them, which prevent from temperature decline on the bark tissues of trunks at night time, were $7.23^{\circ}C$. Waterproof fabric pad showed the highest day and night thermal insulation effects. Thus our results suggest that development of TICMs using waterproof fabric pad might be helpful to protect the bark tissues of trunks from freezing injury.

• Tribology and Lubricants
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• v.37 no.5
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• pp.189-194
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• 2021

A straightforward, yet effective surface modification method of stainless steel mesh and its interesting anti-wetting characteristics are reported in this study. The stainless steel mesh is electrochemically etched, and the specimen has both micro and nano-scale structures on its surface. This process transforms the two types of mesh specimens known as the regular and dense specimens into hydrophobic specimens without applying any hydrophobic chemical coating process. The fundamental wettability of the modified mesh is analyzed through a dedicatedly designed experiment to investigate the waterproof characteristics, for instance, the penetration threshold. The waterproof characteristics are evaluated in a manner that the modified mesh resists as high as approximately 2.7 times the pressure compared with the bare mesh, i.e., the non-modified mesh. The results show that the penetration threshold depends primarily on the advancing contact angles, and the penetration stop behaviors are affected by the contact angle hysteresis on the surfaces. The findings further confirm that the inexpensive waterproof meshes created using the proposed straightforward electrochemical etching process are effective and can be adapted along with appropriate designs for various practical applications, such as underwater devices, passive valves, and transducers. In general, , additional chemical coatings are applied using hydrophobic materials on the surfaces for the applications that require water-repelling capabilities. Although these chemical coatings can often cause aging, the process proposed in this study is not only cost-effective, but also durable implying that it does not lose its waterproof properties over time.

• Proceedings of the KSR Conference
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• 2011.10a
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• pp.3172-3179
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• 2011

Several materials using polymer-portland-cement concrete have developed to have not only strength of attachment with body, but also waterproof function and strong anti-sodium chloride properties. Especially, in case of railway, unlike other public transportation, it is very difficult to doing the repair and reinforcement work of structure during service time. Therefore, the development and study of materials having characteristics of structural strength, unification behavior with body, and resistance of crack are very important. Accordingly, the characteristic of material of polymer based concrete is indicated compared with the experiment and analysis through this study, and suggested application to railway tunnel, bridge, and concrete track structure.