• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.1307-1316
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• 2009

In this case, powerfulness quorum of destruction side which we have expected are supposed general limit value for rock floor when retaining of earth on the section of rock floor in the urban area. For digging in the urban area, there are a lot of dislocations to be disadvantage for safety of digging ants. The displacement of the pondside didn't converged with the phase of the excavation. Also, the speed of displacement got higher than the percentages of risk in the construction. So, we put into operation Face mapping for checking special quality of dislocations which appear on the digging ants. This results were used to decide a destruction in the case of the final excavation by analyzing with other results. It was possible to know the unstable distribution of a fault line in Face Mapping and to get powerful lens of a surface of discontinuity by tests indoors and outdoors. The results were also used to make a solution. Therefore, It's a successful example using the Partial TopDown for stable digging. And it is important that Face Mapping have to be practiced for solving the uncertainty of ground organization when digging design in the urban city.

• Explosives and Blasting
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• v.40 no.4
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• pp.47-56
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• 2022

It was designed as the mechanical excavation mass method on 176m because the safety thing is located around the site. But low-vibration blasting using an electronic detonator was proposed to improve constructability and economy. As a result of the suggestion blasting, both blasting noise and vibration were safe within the allowable limit, confirming the applicability of low-vibration blasting using an electronic detonator to the section. And compared with the mechanical mass excavation method, an economic evaluation was conducted about the section, and it was evaluated that there was an economic advantage as the construction period was reduced by 88 days.

• Journal of Korean Association for Spatial Structures
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• v.24 no.2
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• pp.53-63
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• 2024

The cultural heritage of fortresses is often exposed to external elements, leading to significant damage from stone weathering and natural disasters. However, due to the nature of cultural heritage, dismantling and restoration are often impractical. Therefore, the stability of fortress cultural heritage was evaluated through non-destructive testing. The durability of masonry cultural heritages is greatly influenced by the physical characteristics of the back-fille material. Dynamic characteristics were assessed, and endoscopy was used to inspect internal fillings. Additionally, a finite element analysis model was developed considering the surrounding ground through elastic wave exploration. The analysis showed that the loss of internal fillings in the target cultural heritage site could lead to further deformation in the future, emphasizing the need for careful observation.

• Journal of the Korean Geosynthetics Society
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• v.20 no.1
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• pp.35-44
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• 2021

This research studies the stabilization method for improved soil sloped through the on-site application of Paper Flyash ground stabilizers. The target strength required for improved soil is 500 kPa, and the compressive strength for the slope surface needs to be less than 1,000 kPa after the improvement in order to plant vegetation. To meet this condition, we mixed soil from the site and the ground stabilization material, which is the main material for surface improvement material, performed mixing design and conducted various tests including strength test, permeability test and plantation test. After analyzing the results of the compression test on improved soil slope, we proposed soil constants for the improved soil. In order to evaluate the applicability of the improved soil on the slope, the site construction was carried out on the collapsed slope and the reinforcement evaluation of the surface of the improvement soil was conducted. The stability was not secured before the reinforcement, but the test shows after the reinforcement with improved soil, the safety rate is secured up to 48 hours during the raining period. In addition, the compressive strength of the improved soil at the site was secured at more than 200 kPa adhesion as planned, and the soil hardness test result was also found to be within the specified value of 18-23 mm, which increased the resistance to rainfall and ability to grow plant on the surface for improved soil.

• Journal of Korea Foundry Society
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• v.41 no.6
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• pp.550-557
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• 2021

With the advent of the fourth industrial revolution, the interest in the internet of things (IoT) in manufacturing is growing, even at foundries. There are several types of process data that can be automatically collected at a foundry, but considerable amounts of process data are still managed based on handwriting for reasons such as the limited functions of outdated production facilities and process design based on operator know-how. In particular, despite recognizing the importance of converting process data into big data, many companies have difficulty adopting these steps willingly due to the burden of system construction costs. In this study, the field applicability of IoT-based devices was examined by manufacturing devices and applying them directly to the site of a centrifugal foundry. For the centrifugal casting process, the temperature and humidity of the working site, the molten metal temperature, and mold rotation speed were selected as process parameters to be collected. The sensors were selected in consideration of the detailed product specifications and cost required for each process parameter, and the circuit was configured using a NodeMCU board capable of wireless communication for IoT-based devices. After designing the circuit, PCB boards were prepared for each parameter, and each device was installed on site considering the working environment. After the on-site installation process, it was confirmed that the level of satisfaction with the safety of the workers and the efficiency of process management increased. Also, it is expected that it will be possible to link process data and quality data in the future, if process parameters are continuously collected. The IoT-based device designed in this study has adequate reliability at a low cast, meaning that the application of this technique can be considered as a cornerstone of data collecting at foundries.

• Journal of the Korea Institute of Building Construction
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• v.12 no.4
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• pp.415-425
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• 2012

Green Frame was developed to embody a Green structural system that can provide long life, resource reduction, and availability of remodeling in apartment buildings. Composite precast concrete column and beam, the major structural material of Green Frame, can be installed precisely and promptly through connection of steels and concrete. The connection of Green Frame can be divided into four types, based on the method and characteristics of connection. To select an appropriate type for the site, a comparative analysis of the four types is necessary. The objective of this study is to compare the duration, cost, quality, and safety of four types. The findings of this study can be applied during the selection that appropriate composite precast concrete column reflected project characteristics in design phase.

• Explosives and Blasting
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• v.25 no.2
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• pp.47-60
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• 2007

The blast demolition technology has been used to demolish various industrial facilities and tall buildings since 1950s in the advanced countries such as USA and U.K. It is now considered as one of safe demolition methods in the above countries. In Korea, several companies have tried to introduce blast demolition technology in the early days of the 1990s. However, this technology is still at the beginning stage and not fully adopted due to situation of avoiding technology transfer by overseas technical tie-up companies, lack of objects to be demolished and low level recognition on blast demolition. This technology shall be considered as a cutting edge technology to be applicable to demolition of skyscrapers, various industrial structures and factory buildings in the near future. Blast demolition of a pier structure was carried out under the site condition where there were already the constructed 2 pier structures of up and down line which had safety problems in an expressway construction project. The pier structures need to be demolished and reconstructed for a short period of time in consideration of the construction work process to be followed.

• Magazine of the Korean Society of Agricultural Engineers
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• v.18 no.4
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• pp.4218-4225
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• 1976

To insure the safety of the drainage sluice, topogrophical change due to erosion as well as capability of discharging the design flow in a very important factor. In consideration of the fact that the drainage sluice is built in the sea, its construction has many topographically restricted problems and naturally requires a completeness of research and experiment. This thesis is a comparative and analytic study of discharging flow acting on the erosion at the bottom of the structure on the basis of the measured velocity on the downstream channel of the drainage sluice. (1) The measured velocity shows a little higher values than the computed velocity, because the measured velocity was observed at the surface of the stream. There fore, it is reasonable that the compated velocity should be taken in this study. (2) The field observation was conducted to have the measurement of the flow velocity without surveying the area of flow. Therefore, the coefficient of discharge could not be computed. The survey of the area of flow is planned to be conducted along with the measurement of the flow velocity. (3) The apron of the drainage sluice is free discharging type and it was designed to be about 80m in length less than it should be. (4) The apron of free flow discharging type should have a solid foundation to protect the structure by preventing erosion damage to upstream and downstream channels against weathering of rock and strong torrent. Whether free flow discharging type or energy-dissipating type is best chosen depends on the topographical condition of the forage site, therefore, there would be a comparative study before the final decision was made about the protrection for the structure. (5) It is considered to be appropriate that the design and construction of the drainage sluice should have a complete study which is based on hydraulie model test before the type of protection is decided. (6) It is much requested that a variety of experiment equipments be installed and observed to study the protection for the drainage sluice.

• Journal of the Korean Geotechnical Society
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• v.29 no.12
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• pp.87-94
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• 2013

In recent years, tunnel construction is being increased in order to resolve traffic congestion around urban area, however there are a lot of difficulties due to restrictions such as interference with existing alignment, adjacent structures and cost increase of land acquisition as well as public complaints for negative environmental impacts near the expected tunnel construction site. Therefore, applications of close parallel tunnel have been increasing greatly. But close parallel tunnels cannot guarantee the stability compared with normal parallel tunnel which has enough distance between tunnels. So various methods to strengthen the pillar have been introduced recently, however there is few methods which consider the pillar behaviour in the state of compression. In this paper, the reinforcement methods which reflect the behavior of pillar were reviewed with comparision and analysis by numerical method.

• Advances in concrete construction
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• v.11 no.5
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• pp.375-386
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• 2021

In this paper, a study of stability and health of a newly-built railway tunnel is presented. The field test was implemented to monitor the secondary lining due to the significant cracking behaviors influenced the stability and health of the tunnel structure. Surface strain gauges were installed for monitoring the status of crack openings, and the monitoring outputs demonstrated that the cracks were still in the developing stage. Additionally, adjacent tunnel and poor condition of surrounding rock were identified as the causes of the lining cracking by systematically characterizing the crack spatial distribution, tunnel site and surrounding rock conditions. Reconstruction of partial lining and reconstruction of the whole secondary lining were designed as the maintenance projects for different cracking regions based on the construction feasibility. For assessing the health conditions of the reinforced lining, embedded strain gauges were set up to continuously measure the strain and the internal force of the reconstructed structures. For the partially reconstructed lining, the outputs show the maximum tensile elongation is 0.018 mm during 227 days, which means the structure has no obvious deformation after maintenance. The one-year monitoring of full-section was implemented in the other two completely reconstructed cross-sections by embedded strain gauge. The outputs show the reconstructed secondary lining has undertaken the pressure of surrounding rock with the time passing. According to the calculated compressive and tensile safety factors, the completely reconstructed lining has been in reliable and safe condition during the past year after reinforcement. It can conclude that the aforementioned maintenance projects can effectively ensure the stability and health of this tunnel.