• 산업기술연구
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• 제23권A호
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• pp.119-130
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• 2003

This thesis is results of experimental works on the behavior of the cut-and-cover tunnel. Centrifuge model tests were performed to simulate the behavior of the cut-and-cover tunnels having cross sections of national road and subway tunnels. Model experiments were carried out with changing the cut slope and the slope of filling ground surface. Displacements of tunnel lining resulted from artificially accelerated gravitational force up to 40g of covered material used in model tests, were measured during centrifuge model tests. In model tests, Jumunjin Standard Sand with the relative density of 80 % and the zinc plates were used for the covered material and the flexible tunnel lining, respectively. Basic soil property tests were performed to obtain it's the property of Jumumjin Standard Sand Shear strength parameters of Jumunjin Standard Sand were obtained by performing the triaxial compression tests. Direct shear tests were also carried out to find the mechanical properties of the interface between the lining and the covered material. Compared results model tests estimation with respect to displacements of the lining.

• Ocean Systems Engineering
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• 제5권2호
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• pp.109-123
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• 2015

In the present study, the coupled dynamic response of a Submerged Floating Tunnel (SFT) and mooring lines under regular waves is solved by using two independent numerical simulation methods, OrcaFlex and CHARM3D, in time domain. Variations of Buoyancy to Weight Ratio (BWR), wave steepness/period, and water/submergence depth are considered as design and environmental parameters in the study. Two different mooring-line configurations, vertical and inclined, are studied to find an optimum design in terms of limiting tunnel motions and minimizing mooring-line tension. The numerical results are successfully validated by direct comparison against published experimental data. The results show that tunnel motions and tether tensions grow with wave height and period and decrease with submergence depth. The inclined mooring system is more effective in restricting tunnel motions compared to the vertical mooring system. Overall, the present study demonstrates the feasibility of this type of structure as an alternative to traditional bridges or under-seabed tunnels.

• 한국화재소방학회:학술대회논문집
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• 한국화재소방학회 1997년도 International Symposium on Fire Science and Technology
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• pp.404-412
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• 1997

The pipes and cables buried below ground, which may have helped to improve city landscape, is becoming direct and indirect causes for various kinds of disaster in Korea. Every advantage from the use of utility tunnel can not be converted in a dollar since there is associated huge contribution to safe urban environment. The Korean government has a certain role to play in helping promote utility tunnels for the past years. Most recently, many utility tunnels have been being checked to find out safety level, especially fire safety level, and main problems and shortcomings are checked out as a result of this survey. Because the fire safety level of existing tunnel is low, possible approaches and solutions are presented according to the analysis of fire safety level. In order for these approaches to be effective, existing tunnel should be supplemented appropriately and extra equipment must be installed according to the solutions. Hopefully, by performing both improvement of existing utility tunnel that provide a fire/disaster proof and introducing new types of tunnel which influence utility management and maintenance, the recent disaster rate in Korea can be diminished up to a desirable rate in a near future.

• 한국BIM학회 논문집
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• 제12권4호
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• pp.41-51
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• 2022

BIM was introduced under the leadership of public institutions, and projects such as road, railway, and site creation, including BIM tasks, are currently being ordered. In addition, as the Ministry of Land, Infrastructure and Transport(MOLIT) is pushing for the full design of BIM, public institutions under its jurisdiction are also pushing for the full design of BIM. Full design of BIM means that all designs are done with BIM. Public institutions' BIM guidelines only require BIM deliverables, and there is a limited direction for the BIM design process to respond to traditional design approaches. Therefore, it is necessary to develop a BIM-based design process corresponding to the full design of BIM.

• 한국자동차공학회논문집
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• 제9권6호
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• pp.30-39
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• 2001

The direct injection into the cylinders has been regarded as a way of the reduction in fuel consumption and pollutant emissions. The spray produced by the high pressure injector is of paramount importance in DISI(Direct Injection Spark Ignition) engines in that the primary atomization process must meet the requirement of quick and complete evaporation, mixing with air and combustion especially to prohibit the excessive HC emissions. The interaction between air flow and fuel spray was investigated in a steady flow system embodied in a wind tunnel to simulate the variety of flow inside the cylinder of the DISI engine. The direct Mie scattered and shadowgraph images presented the macroscopic view of the liquid sprays and vapor fields. The velocity and particle size of fuel droplets were investigated by phase doppler anenometer(PDA) system. The processes of atomization and evaporation with a DISI injector were observed and consequently utilized to construct the data-base for the spray and fuel-air mixing mechanism as a function of the flow characteristics.

• 한국자동차공학회논문집
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• 제13권1호
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• pp.1-8
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• 2005

The spray prepared for direct fuel injection into cylinder is of great importance in a DISI(Direct Injection Spark Ignition) engine. The interaction between air flow and fuel spray was investigated in a steady flow system embodied in a wind tunnel to simulate the variety of in-cylinder flow conditions in the DISI engine. The Mie-scattering images presented the macroscopic view of the liquid spray fields interacting with cross-flow Particle sizes of fuel droplets were measured with phase Doppler anemometer(PDA) system. A faster cross-flow field made SMD larger and $D_10$ smaller. The atomization and evaporation processes with a DISI injector were observed and consequently utilized to construct the database on the spray and fuel-air mixing mechanism as a function of the flow characteristics.

• 한국분무공학회지
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• 제10권3호
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• pp.38-44
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• 2005

The direct injection into the cylinders has been regarded as a way of the reduction in fuel consumption and pollutant emissions. The spray produced from the injector of DIS(Direct Injection Spark Ignition) engine is of paramount importance in DISI engines. Fan-spray injector as well as swirl-spray injector was developed and utilized to the DISI engines. The interaction between air flow and fuel spray was investigated in a steady flow system embodied in a wind tunnel to simulate the variety of flow inside the cylinder of the DISI engineer. The direct Mie scattered images presented the macroscopic view of the liquid spray fields interacted with crossflow. Particle sizes of fuel droplets were measured with phase Doppler anemometer(PDA) system. A faster cross-flow field made SMD larger and $D_{10}$ smaller. The experiments show the interaction of air flow field and the fuel spray field of fan-spray. The results can be utilized to construct the data-base for the spray and fuel-air mixing mechanism as a function of the flow characteristics.

• Geomechanics and Engineering
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• 제30권1호
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• pp.27-44
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• 2022

Gravelly soil is a kind of special geotechnical material, which is widely used in the subgrade engineering of railway, highway and airport. Its mechanical properties are very complex, and will greatly influence the stability of subgrade engineering. To investigate the mechanical properties and failure mechanism of gravelly soils, this paper introduced and verified a new discrete element method (DEM) of gravelly soils in large scale direct shear test, which considers the actual shape and broken characteristics of gravels. Then, the stress and strain characteristics, particle interaction, particle contact force, crack development and energy conversion in gravelly soils during the shear process were analyzed using this method. Moreover, the effects of gravel content (GC) on the mechanical properties and failure characteristics were discussed. The results reveal that as GC increases, the shear stress becomes more fluctuating, the peak shear stress increases, the volumetric strain tends to dilate, the average particle contact force increases, the cumulative number of cracks increases, and the shear failure plane becomes coarser. Higher GC will change the friction angle with a trend of "stability", "increase", and "stability". Differently, it affects the cohesion with a law of "increase", "stability" and "increase".

• 지질공학
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• 제33권3호
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• pp.461-474
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• 2023

본 연구에서는 경상북도 청송군 현서면과 안덕면 일원에 설치되어 있는 영천댐 도수터널 구간과 도수터널 주변지역의 지하수위를 측정하여, 도수터널 시공 이전 대비 지하수위 회복여부를 조사하였다. 2017년 9월부터 2018년 8월까지 매월 1회 이상 총 12회에 걸쳐 지하수 관정 156공에 대한 지하수위를 측정하였으며 지하수위 관측조사 결과, 직접 영향구역에 분포하는 관정의 지하수위 값이 간접 영향구역의 값에 비하여 상대적으로 낮은 수치를 보이고 있다. 이러한 결과는 지형조건보다는 지질학적 불연속면으로 작용하는 도수터널에 의한 영향, 즉 지하수 흐름이 직간접적인 경로를 통하여 도수터널로 유출되는 것에 지배적으로 영향을 받는 것으로 추정되며, 향후 지하수 시설물의 유지관리 및 지하수 환경의 보전을 위하여 지속적인 모니터링 및 추가 조사가 필요하다.

• 한국전기전자재료학회:학술대회논문집
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• 한국전기전자재료학회 2009년도 하계학술대회 논문집
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• pp.129-130
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• 2009

The P/E characteristics of $HfO_2$ CTF memory capacitor with $SiO_2/HfO_2/Al_2O_3$(OHA) engineered tunnel barrier were investigated. After a growth of thermal oxide with a thickness of 2 nm, 1 nm $HfO_2$ and 3 $Al_2O_3$ layers were deposited by atomic layer deposition (ALD) system. The band offset was calculated by analysis of conduction mechanisms through Fowler-Nordheim (FN) plot and Direct Tunneling (DT) plot. Moreover the PIE characteristics of $HfO_2$ CTF memory capacitor with OHA tunnel barrier was presented.