• KSCE Journal of Civil and Environmental Engineering Research
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• v.40 no.1
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• pp.35-41
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• 2020

In this study, the stability of low crested structure armoured by rock has been investigated using two-dimensional hydraulic model tests. The effect of wave steepness and freeboard on the rock stability on crest, front, and the rear slope has been investigated. Rocks were mostly damaged near the upper part of the seaward slope and the crest of the seaward side. From the experimental data, the new empirical formula for the stability coefficients of the rocks was proposed.

• Journal of the Korean GEO-environmental Society
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• v.20 no.1
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• pp.57-65
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• 2019

In this study, to investigate the effect of cylindrical countermeasure on the flow characteristics of debris flow, a series of small-scale tests were conducted using a flume with cylindrical baffles. Various heights and row numbers of installed baffles were considered as a test condition. High speed cameras and laser level sensors were also installed at the top and side of the channel, respectively, to capture the debris flow dynamics before and after baffles. Based on test results, the energy dissipation of debris flow due to baffles was analyzed. Test results showed that baffles can significantly reduce the velocity and flow depth of debris flows. The energy dissipation effect of baffles also increase as the increase of height and row number of baffles.

• Proceedings of the KGS Conference
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• 2003.11a
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• pp.29-33
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• 2003

Sandy shoreface에서 외해로 가면서 퇴적물의 입경이 작아지는 퇴적물의 분급이 이루어지고 있다는 것은 잘 알려진 사실이다 (e.g., Inman 1953; Niedoroda et al.,1985; Bailard and Bowen 1981; Guillen and Hoekstra, 1996). 이러한 cross-shore의 퇴적물 입경 분급에 중요한 mechanism은 표층에서 상대적으로 큰 입자들이 bedload로 해안으로 이동하는 반면, 표층에서 높이 부유한 부유 퇴적물이 외해로 운반되는 양 방향 퇴적물 이동이라고 할 수 있다. (중략)

• Explosives and Blasting
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• v.29 no.2
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• pp.67-80
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• 2011

Recently, the number of structure demolitions has increased in both civil and architecture fields due to various reasons such as redevelopment of a city, utilization of sites and restoration of deteriorated structures. In the past, domestic shell structures had been constructed with brick masonry and they were not high. Therefore, their demolition had been executed with ease. Recently, however, taller reinforced concrete shell structures have become a target for the destruction. Under these circumstances, how to efficiently demolish a structure and how to minimize effects of the destruction on environment including vibration and noise have become a main issue. One of the possible solutions is the explosive demolition. In this study, a case of explosives demolition of the stack, which is located in Jeju Thermal Power Plant in Republic of Korea and is 70 m tall, is addressed. In order to fall down the structure against the desired direction, 13.5 kg dynamite and 100 electric detonators were used.

• Journal of Dental Rehabilitation and Applied Science
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• v.40 no.2
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• pp.64-71
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• 2024

Purpose: The purpose of this study is to evaluate Ti-base abutment's three different heights and three different cement types on the pull-off force of zirconia-based restorations. Materials and Methods: A total of 90 fixture lab analogs were embedded in auto polymerizing resin bloack. 90 Ti-base abutments heights of 3 mm, 5 mm, 7 mm were scanned and zirconia restoration were prepared from scanned files. Zirconia restoration were cemented with three different types of cements (temporary, semi-permanent, permanent) following manufacturer's instructions. All 90 specimens were placed and tested in a universal testing machine for pull-out testing. Retention was measured by recording the force at load drop. Statistical analysis was performed using Kruskal-Wallis test for detecting whether there are any statistical significance along cement types or abutment heights. After that, Mann-Whitney test was used for figuring out differences regarding abutment height and the comparison between 3 cements. Results: Temp bond showed significantly lower pull-off force compared to Fujicem regardless of any abutment height. However, there were significant differences between Cem-implant and Fujicem in abutment height of 3 mm and 7 mm, but there was no significant difference in 5 mm. Temp bond and Cem-implant had significant differences only in abutment height of 5 mm. Conclusion: Although Ti-base abutment height did not influenced zirconia restorations' retentiveness, cement types showed significant differences.

• Journal of the Korean Recycled Construction Resources Institute
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• v.4 no.2
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• pp.172-179
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• 2016

For an evaluation of service life in RC(Reinforced Concrete) structures, deterministic method and probabilistic method considering random variables of design parameters are usually adopted. In the work, surface chloride contents which vary with distance from sea shore and height are investigated from the previous research literature surveys, and they are considered for service life estimation. Through the analysis, the probabilistic method shows much lower results, which is due to variations of design parameters and very low intended durability failure. In the deterministic method, the structures within 250m and higher than 60m are evaluated to be free from chloride attack. In the probabilistic method, those higher than 60m in all the region and higher than 40m and 250m from sea shore are evaluated to satisfy the service life.

• Water for future
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• v.29 no.2
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• pp.71-76
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• 1996

• The Korean Publising Journal, Monthly
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• s.219
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• pp.8-8
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• 1997

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.22 no.4
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• pp.230-234
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• 2010

This study examined the effect of wall friction on deformation characteristics of the cellular bulkhead, in terms of artificial wall friction based on the results of model tests according to the existing penetration ratio and loading height. 1. The effect of wall friction on deformation characteristics of the cellular bulkhead turned out to be less as the loading height decreases and the penetration ratio increases. The yield load also becomes less as wall friction decreases. 2. The ratio of the rotational displacement to the horizontal displacement of the cellular bulkhead becomes less as the loading height decreases and the penetration ratio increases. Hence it is concluded that the effect of wall friction has close relationship with the rotational displacement.

• Journal of the Korea institute for structural maintenance and inspection
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• v.15 no.5
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• pp.199-208
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• 2011

The purpose of this study is to evaluate of the strength and deformation capacity of metallic dampers with the variable slit shape. For this purpose, 12 metallic damper specimens were prepared and shear testing was performed. According to the test results, the S shaped metallic damper with the strut height of 200mm and angle of $60^{\circ}$ shows better hysteretic performance than any other specimens. By making a comparison between the yield strength in test and the proposed strength formula, test results shows larger yield strength than calculation method.