• Geomechanics and Engineering
• /
• 제32권6호
• /
• pp.653-671
• /
• 2023

In practice, the interference influence caused by adjacent footings of structures on geo-reinforced loose soil has a considerable impact on their behavior. Thus, the goal of this study is to evaluate the behavior of two strip footings in close proximity on both geocell and geogrid reinforced soil with different reinforcement layers. Geocell was made from geogrid material used to compare the performance of cellular and planar reinforcement on the bearing pressure of twin footings. Extensive experimental tests have been performed to attain the optimum embedment depth and vertical distance between reinforcement layers. Particle image velocimetry (PIV) analysis has been conducted to monitor the deformation, tilting and movement of soil particles beneath and between twin footings. Results of tests and PIV technique were verified using finite element modeling (FEM) and the results of both PIV and FEM were used to utilize failure mechanisms and influenced shear strain around the loading region. The results show that the performance of twin footings on geocell-reinforced sand at allowable and ultimate settlement ranges are almost 4% and 25% greater than the same twin footings on the same geogrid-reinforced sand, respectively. By increasing the distance between twin footings, soil particle displacements become smaller than the settlement of the foundations.

• 한국산업융합학회 논문집
• /
• 제26권3호
• /
• pp.401-409
• /
• 2023

Oscillating water column (OWC) type wave power generator system is a power generation system that uses wave energy, a sustainable and renewable energy source. Irregular cycles and wave heights act as factors that make it difficult to secure generation efficiency of the wave power generator system. Recently, research for improving power generation efficiency is being conducted by applying digital twin technology to OWC type wave energy converter system. However, digital twin using sensor data can predict erroneous performance due to uncertainty in the sensor data. Therefore, this study proposes an uncertainty analysis method for sensor data which is used in digital twin to secure the reliability of digital twin prediction results. Uncertainty quantification considering sensor data characteristics and future uncertainty information according to uncertainty propagation were derived mathematically, and confidence interval estimation was performed based on the proposed method.

• Steel and Composite Structures
• /
• 제42권1호
• /
• pp.139-149
• /
• 2022

To simplify the design and reduce the construction cost of traditional multi-girder structural systems, twin I-girder structures are widely used in many countries in recent years. Due to the concern on post-fracture redundancy, however, twin girder bridges are currently classified as fracture critical structures in AASHTO specifications for highway bridges. To investigate the after-fracture behavior of such structures, a composite steel and concrete twin girder specimen was built and an artificial fracture through the web and the bottom flange was created on one main girder. The static loading test was performed to investigate its mechanical performance after a severe fracture occurred on the main girder. Applied load and vertical displacement curves, and the applied load versus strain relationships at key sections were measured. To investigate the load distribution and transfer capacities between two steel girders, the normal strain development on crossbeams was also measured during the loading test. In addition, both shear and normal strains of studs were also measured in the loading test to explore the behavior of shear connectors in such bridges. The functions and structural performance of structural members and possible load transfer paths after main girder fractures in such bridges were also discussed. The test results indicate in this study that a typical twin I-girder can resist a general fracture on one of its two main girders. The presented results can provide references for post-fracture performance and optimization for the design of twin I-girder bridges and similar structures.

• 한국산업융합학회 논문집
• /
• 제27권1호
• /
• pp.25-37
• /
• 2024

The objective of this study was to create intelligent rail robots that are optimized for facility management and implement digital twin systems for smart road tunnel management. An autonomous surveillance system is formed by combining the sensing platform consisting of railing robots, fixed cameras and environmental detection sensors with the digital twin data platform technology for tunnel monitoring and early fire suppression. In order to develop mobile rail robots for fire extinguishing, we also designed and manufactured robots for extinguishing & monitoring and fire extinguishing devices, and then we examined the optimization of all parts. Our next step was to build a digital twin for road tunnel management by developing continuous image display system and implementing 3D modeling. After constructing prototypes, we attempted simulations by configuring abnormal symptom scenarios, such as vehicles fires. This study's proposal proposes high-accuracy risk prediction services that will enable intelligent management of risks in the tunnel with early response at each stage, using the data collected from the intelligent rail robots and digital twin systems.

• 한국정보전자통신기술학회논문지
• /
• 제16권3호
• /
• pp.138-151
• /
• 2023

우리나라 항만 인프라는 공용연수가 30년이 넘은 노후 항만시설물은 2019년 약 23%에서 2029년에는 47%로 증가하여 노후화가 빠르게 진행되고 있다. 오래된 기존의 항만은 경쟁력을 상실하고 항만 인프라의 발전을 저하하며 시설물에 대한 인적자원 기반 유지보수에 따른 인명사고가 증가한다. 이러한 문제를 디지털 트윈 기반의 체계적인 관리 기술 구축으로 해결하고자 한다. 본 연구는 항만 인프라의 재해와 노후화 현황과 스마트 항만의 사례를 살펴본 뒤 스마트 항만 기술이 반영된 디지털 트윈 구현 단계를 구체적으로 제시하고자 한다. 항만 인프라 연계 시스템을 분석하고 디지털 트윈 구현에 필수적인 시나리오를 작성하여 맵핑을 한다. 재해와 노후화 관리를 위한 3D 모델링과 시뮬레이션 데이터를 수집하여 디지털 트윈을 구현하며 항만 인프라에서 획득한 센싱 데이터, 영상 데이터 등의 데이터를 실시간으로 연동하여 상황별 항만 디지털 트윈 시뮬레이션 구현한다. 항만 인프라 재해와 노후화 관리를 위한 디지털 트윈 항만을 구현하는 경우 실시간 통합관제로 예지적인 항만 인프라 관리로 할 수 있을 뿐 아니라 재해에 관한 안전을 확보할 수 있다.

• 한국분무공학회지
• /
• 제20권3호
• /
• pp.162-167
• /
• 2015

Recently, there has been rising interest in applying urea-SCR systems to large marine diesel engines because the International Maritime Organization (IMO) has decided to enforce NOx reduction regulations. Generally, in the case of urea-SCR of the marine diesel engine, a type of twin fluid atomizer has been using for injection of the urea solution. This study conducted to investigate an effect of the atomization of external-mixing twin fluid nozzle on the conversion efficiency of reductant. The lab-scaled experiment device was installed to mimic the urea-SCR system of the marine diesel engine for this study. In a low temperature inflow gas condition which is similar with the exhaust temperature of large marine diesel engine, this study found that the conversion efficiency of reductant of when relative big size urea solution droplets are injected into exhaust gas stream can be larger than that of when small size urea solution droplets are injected. According to results of this study, the reason was associated with decrease of reaction rate constant caused from temperature drop of inflow gas by assist air of twin fluid atomizer.

• 대한용접접합학회:학술대회논문집
• /
• 대한용접접합학회 2000년도 특별강연 및 추계학술발표대회 개요집
• /
• pp.50-53
• /
• 2000

• 집단에너지
• /
• 통권4호
• /
• pp.36-39
• /
• 2006

• 한국해양공학회지
• /
• 제12권1호
• /
• pp.128-134
• /
• 1998

This study is carried out the theoretical studies on wave transmission and motions in waves of twin hull type floating breakwaters with the vertical and horizontal plate. The method of calculation is based on the three dimensional singularity distribution method. The results show that wave transmission is affected by heave motion. Twin hull type is designed by the use of the theoretical method and good performance of the developed floating breakwater is confirmed for longer wave period.

• Wind and Structures
• /
• 제10권4호
• /
• pp.383-398
• /
• 2007

The paper describes a study of the effects of structural coupling on the wind-induced response of twin tall buildings connected by a skybridge. Development of a dual high-frequency force balance used in wind tunnel investigation and background information on the methodology employed in analysis are presented. Comparisons of the wind-induced building response (rooftop acceleration) of structurally coupled and uncoupled twin buildings are provided and the influence of structural coupling is assessed. It is found that the adverse aerodynamic interference effects caused by close proximity of the buildings can be significantly reduced by the coupling. Neglecting of such interactions may lead to excessively conservative estimates of the wind-induced response of the buildings. The presented findings suggest that structural coupling should be included in wind-resistant design of twin tall buildings.