• Journal of the Korea institute for structural maintenance and inspection
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• v.21 no.3
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• pp.93-101
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• 2017

The shortage of parking lots in aged apartment complexes built from the 1980s to the mid 1990s is serious. When we look at the case of parking lot expansion in the aged apartment complexes, the method of extending the underground parking lot vertically occupies the majority. It is very important to secure the structural safety of the foundations when the existing buildings are enlarged. In the case of underground vertical work, the work space should be narrow, so that a method with excellent safety, environmental and construction properties should be applied. Urban construction is also required to use construction methods and equipment with low noise and vibration. This study analyzed the factors influencing the selection of the foundation reinforcement method for the expansion of the underground parking lot and Weights of influence factors were calculated. The purpose of this study was to analyze the applicability of the foundation reinforcement method. Factors influencing the applicability of the foundation reinforcement method were derived through expert interviews and The AHP technique was used to calculate the weight of the influencing factors. It was evaluated by experts on the applicability of the foundation reinforcement method. It conducted a case study on two types of underground parking lot expansion type and compared the applicability of the foundation reinforcement method.

• Proceedings of the Korean Geotechical Society Conference
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• 1992.06a
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• pp.57-86
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• 1992

본 연구에서는 기존의 PC말뚝과 PHC말뚝의 시공성과 지지력에 대한 비교확인 시험의 결과를 근거로 하여 PHC말뚝의 시공상의 장점, 특성 및 경제성을 파악하였으며, SIP공법에 의하여 PHC말뚝을 사용시 기존 PC말뚝이나 강관말뚝보다 경제성이 우수함을 확인하였다. 또한 PHC말뚝은 압축강도와 지지혁이 기존 PC말뚝보다 높을 뿐만아니라 강관말뚝과 같이 용접이음이 가능하고 말뚝의 심도가 깊은 경우에도 강관말뚝과의 대체시공이 가능하여 PHC말뚝의 성능을 극대화할 수 있는 적절한 항타장비를 사용하는 경우에는 혁신적인 원가절감이 가능함을 확인할 수 있다.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2004.05a
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• pp.100-100
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• 2004

미국에서 발명된 초미세 발포기술은 기존의 발포공법과는 달리, 가스(CO2, N2)에 의해 재료에 생성된 기포(셀)의 크기가 loom이하인 작은 셀이 재료 내에 고르게 분포되도록 하여, 기존의 발포재료보다 나은 기계적 특성을 유지하도록 하였다. 그 결과, 제품의 재료비를 절감하기 위해 연구된 MCPs는 기존의 발포기술과는 달리 재료의 기계적 강도 저하를 극복하고 충격 강도와 인성의 향상을 가져왔다. 그리하여, 현재 국내의 자동차업체의 범 퍼 및 내장재로의 사용을_시작으로 산업의 다각적인 분야에 이용되고 있다.(중략)

• Korean Chemical Engineering Research
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• v.52 no.4
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• pp.503-515
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• 2014

A lot of existing wastewater treatment plants (WWTPs) are rebuilt or retrofitted for advanced wastewater treatment processes to cope with reinforced effluent criteria of nitrogen and phosphorous. Moreover, how to treat the wasted sludge from WWTPs has been also issued since the discharge of the wasted sludge into ocean is impossible from 2011 due to the London Convention 97 protocol. These trend changes of WWTPs get a motivation to assess environmental and economic impacts from the construction stage to the waste stage in WWTPs. Therefore, this study focuses on evaluation of environmental and economic impacts of the advanced wastewater treatment processes and waste sludge treatment process by using life cycle assessment. Four advanced wastewater treatment processes of Anaerobic/Anoxic/Oxic ($A_2O$), 5 stages-Bamard Denitrification Phosphate (Bardenpho), Virginia Initiative Plant (VIP), and Modified University of Cape Town (MUCT) are chosen to compare the conventional activated sludge (CAS) and three waste sludge treatment methods of land fill, incineration, and composting are used. To evaluate environmental and economic impacts of each advanced wastewater treatment processes, life cycle assessment (LCA) and life cycle cost (LCC) are conducted based on International organization for standardization (ISO) guidelines. The results clearly represent that the $A_2O$ process with composting shows 52% reduction in the environmental impact than the CAS process with landfill. On the other hand, the MUCT process with composting is able to save 62% of the life cycle cost comparing with the CAS process with landfill. This result suggested the qualitative and quantitative criteria for evaluating eco-environmental and economic technologies of advanced treatment processes and also sludge treatment method, where their main influence factors on environmental and economic impacts are analyzed, respectively. The proposed method could be useful for selecting the most efficient and eco-friendly wastewater treatment process and sludge treatment method when retrofitting the existing WWTPs to advanced treatments.

• Journal of the Korea Institute of Building Construction
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• v.17 no.4
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• pp.349-360
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• 2017

In concrete construction work, formwork is an important process that accounts for 10% of the total construction cost. Recent buildings are becoming bigger and higher. In order to maximize the efficiency and safety of this formwork, the system of formworking has been systematized. However, the human accidents and the noise complaints arise from dismantling processes frequently occur. In order to solve these problems, most of them are dependent on foreign technology, but they do not take into consideration the conditions of domestic construction site. In this study, we developed a table type multi-drop system form for a slab and beam which can improve the process, safety and reduction of disassembly noise, and evaluated the physical properties of the main members which are used in the system. The results of this study show that there is sufficient strength to be used as a slab and a laying material for both a yoke beam and a supporting post. The noise level is improved compared to existing method.

• Proceedings of the KSR Conference
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• 2010.06a
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• pp.880-894
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• 2010

The Grout injected precast pile is widely used in rapid-transit railway bridge recently. The existing portland cement of well used filling at injected precast method that with low strength and environmental pollution, unstable in which ground water contamination by cement flow out, ground relaxation by water down, decrease of horizontality resistance and durability and load transfer divide etc. In particular, as in rapid-transit railway bridge need to secure safety from different angle with vibration of high speed train, horizontal force when train stop and earthquake. Works of foundation construction consider to requirements of the times to coal yard green growth. Together, new green foundation method for possible economics and securing of reduce the term of works are material to developments. Therefore, we carried out study that it is using and development new concept environment - friendly filling include durability and earthquake resistance, for secure safety and minimize environment pollution. To achieve this, we carried out difference tests that new green fillings of underwater concrete, high liquidity, high viscosity, early stiffness as compared to existing portland cement fillings. As results, new green filling have outstanding application at precast pile method and micropile construction method with vertical bearing capacity, horizontal bearing capacity and many case. From now on we will be looking forward to development of new environment-friendly foundation method from various further studies.

• Geotechnical Engineering
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• v.14 no.5
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• pp.5-16
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• 1998

2-D numerical methods have been applied to analyze the stability of tunnels because of computation efficiency, though the ground around the tunnel under construction shows 3-D reformational behaviour due to the transverse and longitudinal arching effects. Load distribution factors are introduced to the 2-D analysis for the consideration of the effects of the tunnel advance in three dimensions. The load distribution factors influence significantly the ground deformation and the load of primary supports like shotcrete and rockbolts. According to the previous studies for 3-D numerical studies. it was shown that load distribution factors were heavily dependent on the ground deformational properties, tunnel size and the advance length of a tunnel. However, as the quantitative methods evaluating the factors have not been presented yet, constant values have been assigned to the factors for 2-D analysis even if the conditions for tunnel design are different. Accordingly, this paper presents the method to evaluate quantitatively the load distribution factors through the regression analysis of 3-D analysis data on 72 design cases. Also, new modification to the load distribution factors are suggested for the ring-cut excavation method because the conventional 2-D analysis is not able to consider the support effects of the core left on the tunnel face.

• Journal of Korean Association for Spatial Structures
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• v.4 no.3 s.13
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• pp.85-91
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• 2004

Rehabilitations of reinforced concrete(RC) structures using advanced fibre-reinfored plastic(FRP) composites has become very popular in last few years. Typical method of strengthening strategy using FRP composite is bonding the CFRP plate or sheet on the surface of existing concrete structures. Many researches, however, have shown that bonding FRP plate or sheet on the surface of concrete has tendancy to debond prematurely induced by stress concentrations at the end of the plate. In order for overcoming the premature failure, the filling-up method which places FRP-rod into the existing concrete sawing groove has been developed. Through filling-up test results, aims of this research is to investigate the efficiencies of the filling-up method and is to determine the availabilities of traditional flexural theories that has provided all over the world.

• Journal of Korean Society of societal Security
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• v.3 no.2
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• pp.57-64
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• 2010

In this study, the behavior and safety of an existing tunnel and its facilities are investigated when a new tunnel adjacent to the existing tunnel is blasted. The design of the new tunnel puts priority on stability of the tunnel itself over the safety of the facilities which are installed within the existing tunnel such as jet fans. And thus, a detailed consideration on securing the safety of the existing facilities has been insufficient. An analysis on the types of traffic accidents in the last ten years shows that most incidents were due to the driver's improper response in emergency situations and unexpected obstacles. In consideration of this analysis, the safety of the facilities in the existing tunnel was secured by minimizing the charging amount for each hangfire and changing the excavation method of evacuation communication shelters to the large center hole cut blasting method to reduce blasting vibration. For a more quantitative analysis, measurement devices were installed inside the existing tunnel, at houses adjacent to the new tunnel, near jet fans in the existing tunnel. This enabled real time measurement of displacements of the existing tunnel, adjacent houses, and jet fans without interrupting traffic flow. Therefore, the improvements of charging amount for each hangfire, the blasting method, and the measurement method are suggested in this paper to secure the safety of the facilities in the existing tunnel when a new tunnel, located on a large city and adjacent to an existing tunnel, is designed.

• Korean Journal of Construction Engineering and Management
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• v.9 no.2
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• pp.99-107
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• 2008

Rapidly increasing automobile supply rate according to improved economic level of life makes lack of parking space of apartments. Even though the initial design of parking space compiled with old regulations, it may not observe either new laws or requirement of inhabitants. Even if old apartments have no structural durability problem, outworn facilities and insufficient parking area may be a main reason for reconstruction. It causes waste of national resources and makes recycling issues. Additionally, irregularly parked cars make traffic obstruction to a fire engine and result in many fire accident victims. Parking problems of apartments are not only inconvenience but also serious safety issues. From these points of view, remodeling only for parking area expansion is necessary to avoid overall reconstruction of apartments. The purpose of this study is to suggest a retaining wall selection method for apartments underground parking lots expansion without evacuation of resident people. Effect factors to select retaining wall system are analyzed and weight values are calculated by applying AHP. One selection method of retaining wall is proposed by evaluating applicability and its sensitivity analysis is executed. This selection method is expected to help decision-making of retaining wall system selection.