• KSCE Journal of Civil and Environmental Engineering Research
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• v.38 no.2
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• pp.311-317
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• 2018

The new asphalt surface reinforcement method (ASRM) is one of the preventive maintenance methods in asphalt concrete pavements. The adhesion performance of new ASRM satisfied the standard of non-slip pavement and bridge waterproofing materials. As a results of durability tests (as wheel load, rolling bottle and UV resistance test), the new ASRM showed sufficient resistance to traffic and environmental loads. The waterproof and chemical resistance tests of new ASRM were conducted to evaluate whether the pavement could be protected from water and chemicals and the performances of new ASRM were satisfactory. Furthermore, the new ASRM demonstrated some rejuvenation effects due to its toughness increases in recycled asphalt concrete mixture by 5% compared to the conventional hot mix asphalt mixture using reclaimed asphalt pavement. In conclusion, the new ASRM was evaluated to protect the asphalt concrete pavement and increase the lifetime.

• Journal of the Korean Geotechnical Society
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• v.33 no.12
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• pp.115-125
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• 2017

PHC-W earth retaining wall could be constructed continuously. Various retaining wall methods such as C.I.P. etc. method require separate waterproof method. However, the PHC-W retaining wall method prevents leakage of groundwater by inserting a waterproofing material at connection part between 2 PHC piles. In this study, the experimental study on 3 waterproofing method for PHC-W retaining wall was conducted at the model pressure chamber. In the method using textile with 1-liquid type and 2-liquid type urethane, rapid leak occurred at the pressure of 120 kPa and 140 kPa or more. In the method of textile with grouting, rapid leak occurred at the pressure of 120 kPa or more, however, in this method, the rapid leakage happened at the top part and the bottom part reinforced with urethane.

• Journal of the Korea Institute of Building Construction
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• v.16 no.2
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• pp.125-131
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• 2016

According to the increment of urban buildings, the demand of eco-environment space will be also increased. Therefore, the artificial ground green system on a roof will be supplied gradually. In this study, the concept of simplification, unification and prefabrication was widely applied to supply green system. Consequently, the box unit system with a continuous soil layer was developed, and adhesive property, wind resistance and insulation property of this system were evaluated for site application. As a results of adhesive property and wind resistance test, comparing with design wind pressure and wind velocity, this system was safe at the height of 100m building located in urban. In addition, results of temperature measurement for 120 days showed 17% higher insulation property at daytime and 45% higher insulation property at night than normal box unit system owing to continuous soil layer.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.1023-1037
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• 2018

The interest in the use of shield TBM (Tunnel Boring Machine) on the tunnel excavation has been increased rapidly in Korea. The shield TBM tunnel is generally designed as non-drainage tunnel. Consequently, if water leakage through the segment joints happens, big problems on the usage and stability of tunnel can be occurred. In this study, the variation of waterproof capacity of hydrophilic rubber waterstop and gasket, respectively by the construction error and excessive displacement of segment was studied. The test results show that hydrophilic rubber waterstop has favorable on the offset, however unfavorable on the gap. On the other hand, gasket has unfavorable on the offset, however favorable on the gap.

• Composites Research
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• v.21 no.3
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• pp.1-8
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• 2008

The main objective of this study is to investigate the effect of salt water on the mechanical properties of a carbon-epoxy composite material. Specimens were made of a carbon-epoxy composite USN125 and tested under inplane tension and shear after 0, 0.5, 1, 2, 3, 6, 9, and 12 months immersion in 3.5% salt water. Waterproof painting and acceleration technique were not applied. The tensile strengths and moduli in fiber and matrix directions did not show any remarkable degradation until 12 months immersion. In contrast to the tensile properties, shear strength and modulus started to degrade from the early stage of the immersion time and gradually decreased to 36% and 46% of dry values, respectively, after 12 months immersion.

• Journal of the Korean Society of Fisheries and Ocean Technology
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• v.58 no.2
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• pp.153-158
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• 2022

A telesounder is a device that can monitor the appearance of fish in the sea on land and store fish detection data. This study was conducted to monitor the appearance of fish resources in coastal or near seas by using LTE communication for data transmission of the telesounder. The purpose of this study was to develop a prototype telesounder that can monitor the appearance of fish groups in the waters about 50 km away from the coast and store fish detection data. In this study, the prototype telesounder including a fish finder, communication device and battery for stable operation at sea was developed. The stability of telesounder buoy, data transmission/reception and expected use time were investigated. The expected use time of the telesounder using LTE communication with a lithium battery (12 V, 120 Ah) was about 274 hours under the conditions of 10 minutes off and 10 minutes on, about 520 hours under the conditions of 30 minutes off and 10 minutes on, and about 142 hours under continuous conditions. As a result of the sea test, it was found that the telesounder can be used in the sea area moved about 34 km from the land and the telesounder buoy was evaluated to have secured basic stability (buoyancy balance, waterproof, antenna strength, etc.) for operation in a marine environment.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.42 no.2
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• pp.181-186
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• 2022

Dam slope RIM is a highly important contact interface where the main body and the base surface are connected. In general, when the grouting for the slope of the dam structure is designed, it is planned using limited data (drilling, geological map, etc.). This makes it very difficult to accurately consider the original ground characteristics of the slope RIM grouting target, In addition, when the grouting volume planned during the design is drilled and injected into the original ground where the waterstop is secured, there is a possibility that the original ground with the waterstop is disturbed and the effect of the waterstop is rather diminished. In order to overcome such problems, it is more suitable to first consider geological conditions and determine whether to perform optimal grouting on the original ground through on-site repair tests before performing RIM grouting. In this paper, to determine the grouting of the RIM unit, a pilot hole water pressure test was performed on the rock of the slope in the target section. The analysis shows grouting volume of 1 Lugeon or less, and the cement injection amount also shows the injection result of 1 kg/m or less. In this case, performing grouting is rather counterproductive. This result can be evaluated through a rock of which some degree of order of mass is secured, as it is a dam design standard of 1 Lugeon or less when analyzed, using the results of visual observation and geological map creation during slope cutting. Therefore, in conclusion, it is preferable to make the decision for using RIM grouting on the slope of the dam body structure, based on 1 Lugeon in a rock state, and the cement injection amount also at 1 kg/m.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.37 no.6
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• pp.1043-1051
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• 2017

Asphalt overlay on deteriorated concrete pavement has a problem of early damage due to reflective cracking. There is a need for a new method capable of reducing reflection cracking and ensuring the durability of pavement. The purpose of this study was to obtain durability of asphalt overlay with stress absorbing membrane interlayer (SAMI) using epoxy asphalt binder. The tensile performance, durability, water resistance and bonding performance of Epoxy-SAMI were evaluated by various tests. As a result of tests, Epoxy-SAMI meets the quality standard of the bridge waterproofing material. The repeated direct tensile test was carried out to investigate the effect of reflective cracking reduction. When the Epoxy-SAMI was applied, it had 1.2~1.56 times higher reflective cracking resistance than PSMA asphalt concrete with the thickness of 10cm even if the section thickness decreased. 4-point bending beam test results showed the number of fatigue failures increased 7.5 times when Epoxy-SAMI was applied. The Epoxy-SAMI was found to be effective in improving the durability of the asphalt pavement overlay because it serves to prevent reflective cracking, increase lifespan, and function as a waterproof layer.

• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.2
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• pp.283-299
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• 2017

The leakage of tunnel causes the long-term durability of the structures such as concrete lining to deteriorate. The cause of durability degradation can be various substances contained in groundwater such as chloride, sulphate, water, and gas. In this study, a series of test were carried out to determine the watertightness performance and the resistance to salt water of the spray-applied membrane used as non-structural rock support or as a waterproof material for tunnels. As a result, it was found that the penetration of water could occur in a specimen, and the reason was that the internal pores generated by the mixing of the liquid polymer and the powder material and the internal pores were connected by the water pressure. The tensile strength of the test specimens immersed in distilled water and saline water was found to be reduced to less than half of the tensile strength in normal condition. In addition, The elongation was measured to be higher in distilled water than in salt water. However, this result will require further investigation.

• Journal of Korean Ophthalmic Optics Society
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• v.11 no.3
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• pp.281-291
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• 2006

The aim of this study was performed the clinical test using Netspeg lens for good visual acuity on subjects with abnormal refraction status. The subjects of one hundreds adults (fifty males, fifty females, mean=21 years, range=19 to 24) were recorded. The subjects were researched the history including the systemic health, medication, genetics, allergy, systemic disease and ocular disease. The refraction test was recorded the monocular and binocular using objective method. Visual acuity was performed the binocular status using the Netspeg lens and CR-39. Stereopsis test was performed the titmus fly and TNO at near distance using Netspeg lens and CR-39. The P-VEP test was used the 16 pattern size(Bausch Lomb, production in USA) with three channels. Also Subjects viewed the p-vep stimulus with binocular vision through the corrected visual acuity using the Netspeg lens and CR-39. The contrast sensitivity test was performed the contrast sensitivity chart(pelli-Robertson, USA) at 1m distance using the Netspeg lens and CR-39. The ultrastructure of surface on the Netspeg lens and CR-39 was observed the SEM(JMS-5800, made in Japan). The results of this study was as follows: 1. In corrected visual acuity of abnormal refraction using the Netspeg lens and CR-39, the Netspeg lens wearer were acquired the good visual field and clear visual acuity comparative to CR-39 wearer in the subject vision test. however the comfort of visual acuity was similar results in the Netspeg lens and CR-39. Also the subjects of Netspeg lens wearer was good visual acuity more than CR-39 wearer and in the analysis of P-VEP, the amplitude of wave on Netspeg lens used appears to be better through the CR-39(p>0.5). Besides, on the contrast sensitivity, the Netspeg lens wearer was good results than CR-39. The value on stereopsis with TNO by Netspeg lens wearer was better than CR-39 in results. However, in the stereopsis test with Titmus, the Netspeg lens and CR-39 wearer was similar results. 2. The ultrastructure of Netspeg lens surface was the smooth and fine shape more than CR-39. Also, Netspeg lens have a fine line structure in ultrastructure. In conclusion, the results of this study conformed that the surface ultrastructure of Netspeg lens used is more specific pin hole design structure than CR-39. This study indicated that the vision of Netspeg lens used have a better than CR-39 in the corrected visual acuity for abnormal refraction eye. Therefore, In this paper, we suggested that the ultrastructure and line structure of Netspeg lens was related to good visual function. However the visual function of the aspheric Netspeg and ultra waterproof Netspeg lens was similar results.