• Geotechnical Engineering
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• v.14 no.6
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• pp.17-32
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• 1998

The Bakun hydroelectric project includes the construction of a hydroelectric power plant with an installed capacity of 2,520MW and a power transmission system connecting to the existing transmission networks in Sarawak and Western Malaysia, The power station will consist of a 210m height concrete faced rockfill dam. During the construction of the dam and the power facilities the Balui river has to be diverted by three diversion tunnels with a length of some 1,400m each. The inner diameter of the tunnels is 12m and the tunnel width is 16m at the portal area. This paper describes the stability analysis and design methods for the open cut rock slopes in the inlet and outlet area of the diversion tunnels. The geotechnical parameters employed in stability calculations were given as a function of four. defined Rock Mass Types (RMT) which were based on RMR system from Bieniawski. The stability calculations procedure of the rock slopes are divided into two stages. In the first stage, it is calculated for the stability of each 'global' slope without any rock support and shotcrete system. In the second stage, it is calculated for each 'local'slope stability with berms and supported with rock bolts and shotcrete. The monitoring instrumentation was performed continuously and some of the design modification was carried out in order to increase the safety of failed area based on the unforeseen geological risks during the open cut excavation.

• Journal of the Korean Association of Geographic Information Studies
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• v.20 no.2
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• pp.32-46
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• 2017

Recent rapid urban expansion and crowding of various industrial facilities has affected the features of a significant part of downtown area, resulting in areas having buildings with a wide range of height and the foothills. To compute a velocity pressure exposure coefficient, namely the design wind speed factor, this study defines ground surface roughness by utilizing concentration analysis for the height of each building. After obtaining spatial data by extracting a building layer from digital maps, the study area was partitioned for the concentration analysis and to allow investigation of the frequency distribution of building heights. Concentration analysis by building height was determined with the Variation-to-Means Ratio (VMR) and Poisson distribution analysis using a buildings distribution chart, with statistical significance determined using Chi-square verification. Applying geographic information systems (GIS) with the architectural information made it possible to estimate a velocity pressure exposure coefficient factor more quantitatively and objectively, by including geographic features, as compared to current methods. Thus, this method is expected to eliminate inaccuracies that arise when building designers calculate the velocity pressure exposure coefficient in subjective way, and to help increase the wind resistance of buildings in a more logical and cost-effective way.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.5
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• pp.485-500
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• 2020

Due to various advantages such as small facilities, ease of construction and so on, the grouting technology which is widely used in construction field has developed remarkably compared with the past. However, the efforts to improve the homogeneity of quality, long-term durability and environmental problems have been continued. In recent years, new grouting method has been developed in order to solve problems such as low strength, durability and leaching phenomenon of liquid glass (sodium silicate) grouting material in Korea. A newly developed method integrates the injection material with the ground by the self-healing material of crystallization growth type. For this reason, it is known that improvement of the durability and water quality of the ground, prevention of leaching, and environment friendliness can be expected. The present study applied a newly developed method to test sites and verified its effect such as injection range, improvement effect, waterproofing performance and so on. Standard penetration test, field permeability test, borehole shear test, pressuremeter test and pH test were conducted, and the results were compared between before and after developed method application. As results of tests, the field applicability and improvement effect of developed method were proved to be excellent.

• Journal of Korean Society of Disaster and Security
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• v.13 no.2
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• pp.39-51
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• 2020

Recently, flood damage has been increasing in Korea due to frequent local torrential rains caused by abnormal weather conditions. According to the calculation of the recurrence period of torrential rain that occurred in North Chungcheong Province on July 16, 2017, it was estimated that the rainfall frequency in the upper are of Goessan Dam was around 1,524 years, and the highest level of Goesan Dam rose to EL.137.60 meters, leaving only 5 cm of margin until the height of the dam floor (EL.137.65 meters). The Goesan Dam, which operated for 62 years since 1957, needs to be prepared to cope with the increase of floodgate volume in the basin, the development of a single purpose dam for power generation only, and there are no measurement facilities for flood control, so efficient operation methods are needed to secure the safety of residents in upper and lower regions. In this study, a method of dam operation was proposed by constructing a rain matrix for quick decision making in flood prediction, calculating the highest level of dam for each condition in advance, and preparing a survey table, and quickly finding the level corresponding to the conditions in case of a situation.

• Journal of the Korean GEO-environmental Society
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• v.14 no.10
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• pp.39-47
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• 2013

Recently, there have been various domestic construction activities related to the reclamation of the dredged soils to expand the land use. However, the reclaimed grounds made of the dredged soils cause various problems due to highly compressible and low shear strength nature. Particularly, this nature induces huge problems in case of the harbor facilities and road construction on the reclaimed sites. Furthermore, in the reclamation activities, the marine dredged soils are often used instead of the well sorted sand, which induces problems of compressibilities. Therefore, in this study, the mechanical characteristics of artificial soil mixture of kaolinite representing the marine dredged soils and the pond ash. A large consolidometer is designed and manufactured to produce the artificial soil mixture. To represent various mixing ratio between the fly ash and bottom ash in the pond ash, six samples with the same stress history are made with different mixing ratio among kaolinite, bottom ash and fly ash. Isotropically consolidated and undrained compression tests are performed to investigate the shear characteristics of soil mixtures. Based on the experimental results, as the components of mixed ash increase, the friction angle increase and the cohesion values decrease. Also, the porepressure parameters at failure, Af increase with the mixing components of the pond ash. The portion of bottom ash has more impact on the shear behavior than that of fly ash.

• Proceedings of the Korean Institute of Navigation and Port Research Conference
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• 2006.06b
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• pp.163-170
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• 2006

Together with the trend of enhancement in domestic industrial development and economic progress due to import and export, the demand for construction of the roads, bridges, especially port facilities, and several coastal protection and ocean structures is increasing rapidly. MOMAF of Korean Government is driving construction of 9 new ports and renovation of the existing fishery ports. Among these structures most of bridge base, wharves, dolphins, quays, and jetties are being newly built of steel or concrete pile. As the base, supporting bulkheads, and piles are underwater after construction, it is difficult to figure out the status of structures and not enough to get maintenance and strengthen the structures. Every year, moreover, these works suck the government budget due to higher incomplete maintenance expense for protection from corrosions of structures and increased underwater construction period. For the purpose of cutting down the expense of government budget, it is necessary to extend the life cycle of the existing structures. Therefore, we developed a new method for maintenance of submerged structures near the waterline by allowing dry work environment with the floating caisson. The method shows easy to move around the working area and handle. It also showed not only a significant reduction maintenance expenses and time for anti-corrosion work but also better protection. This will be a milestone to reduce the maintenance and construction expenses for the shore and water structures.

• Journal of Korea Water Resources Association
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• v.40 no.6 s.179
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• pp.485-494
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• 2007

This study was performed to evaluate the environmental qualities of the revetment construction methods and the river-facility materials using Life-Cycle-Assessment(LCA) for the nature-friendly design of close-to-nature river, The investigation results on the environmental qualities of energy and materials used to the close-to-nature river plan showed that the environmental impacts per unit weight increased in the order of gasoline > diesel > cement > wood. The environmental impacts per unit area of revetment construction method exhibited that the environmental loadings increased in the order of gabion > revetment > cribwork. In addition, it was observed that the environmental impact was reduced by improving the materials of zinc-galvanized wire. The model basin investigated in this study was the $0.3km^2$ area of river improvement works in Kyung stream, which is a tributary to the Seomjin river and the second regional stream. The research was conducted based on the 30years by life expectancy of artificial facilities. For the comparisons of revetment techniques with respect to the environmental qualities, the method resulted in the highest environmental loadings. The method using ready-mixed concrete ranked second in the environmental loadings of revetment techniques. The present results of this study are expected to play a beneficial role in the nature-friendly design of close-to-nature river by quantitatively identifying the environmental quality of total procedures (i.e., combination of techniques, selection of river-facility materials, maintenance of river-facility) applied to close-to-nature river plan.

• Journal of the Korea institute for structural maintenance and inspection
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• v.25 no.4
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• pp.12-19
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• 2021

Recently, with frequent earthquakes around the world, research on seismic design and seismic reinforcement of reinforced concrete facilities has been actively conducted from earthquakes. In particular, columns, which are compressed members of reinforced concrete structures, are vulnerable to lateral forces caused by earthquakes, so an appropriate seismic reinforcement method is required. Therefore, this study intended to develop Velcro seismic reinforcement method that is quick and easy to construct. For the development of Velcro seismic reinforcement, the adhesion and tensile strength of the existing industrial velcro was improved. A direct tensile test was also conducted to compare the tensile performance of the newly-developed velcro seismic reinforcement to industrial one. In addition, numerical analysis was performed to predict the seismic performance of RC columns reinforced by industrial and newly-developed velcro. Based on the analysis results, the strength and ductility of the non-seismic and velcro-reinforced RC column were reviewed. The analysis confirmed that both the strength and ductility of non-seismic RC columns reinforced by industrial and newly-developed velcro increased, but the seismic performance of the newly-developed Velcro reinforcement is better than that of industrial velcro.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.20 no.6
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• pp.142-149
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• 2019

In this study, the past erosion history and current status in the CHUNG-UI beach of Eulwang-dong, Jung-gu, Incheon-Si, South Korea were investigated and analyzed the wave with wave-induced current to investigate the causes of coastal erosion. As a result, the significant wave height ($H_{1/3}$) was in the range of 0.07~1.57 m and the mean value was 0.21 m. The maximum wave height ($H_{max}$) was in the range of 0.02-4.76m and the mean value was 0.27m. The vertical wave height and cycles were estimated through numerical model experiments of wave transformation. The 50-year frequency design wave height ranged from 0.82m to 3.75m. As a result of the experiment of wave-induced current, wave-induced current in the CHUNG-UI beach was decreased after the installation of the Detached breakwater and the Jetty. On the other hand, when the crest elevation was increased up to 5 m, there was no significant change, but when the crest elevation was increased to 8m, strong wave-induced current occurred around the submerged breakwaters due to lowered depth of water. In addition, the main erosion of the CHUNG-UI beach is due to the intensive invasion of the wave characteristics coming from the outer sea into the white sandy beach. The deformation of the wave centered on the front of the sandy beach caused additional longshore currents flowing parallel to the sandy beach and rip currents in the transverse direction, thus confirming that the longshore sediment was moved out of the front and out of the sea. The results of this study can be used as preliminary data for the recovery of the sand and the selection of efficient erosion prevention facilities.

• Journal of the Korean GEO-environmental Society
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• v.19 no.12
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• pp.25-32
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• 2018

This paper investigates the effect of rock discontinuities on a shear stress wave that is induced by earthquake or blasting and provides the result of numerical parametric studies. The numerical tests of different conditions of rock and discontinuity have been carried out after confirming that the numerical approach is valid throughout a verification analysis from which the test results were compared with a theoretical solution. In-situ stress condition was considered as a rock condition and internal friction angle and cohesive value, which are the shear strength parameters, were considered as discontinuities condition. The joint inclination angle was also taken into account as a parameter. With the various conditions of different parameters, the test results showed that a shear stress wave propagating through a mass is highly influenced by the shear strength of discontinuities and the condition of joint inclination angle as well as in-situ stress. The study results indicate that when earthquake or blasting-induced dynamic loading propagates through a jointed rock mass or a stratified soil ground the effect of in-situ stress and discontinuities including a stratum boundary should be taken into account when evaluating the dynamic effect on nearby facilities and structures.