• Geomechanics and Engineering
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• v.21 no.2
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• pp.111-122
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• 2020

In most cases in urban areas, construction of divergence tunnel should take into account proximity to existing tunnel in operation. This inevitably leads to deformation of adjacent structures and surrounding ground. Preceding researches mainly dealt with reinforcing of the diverging section for the stability including the pillar. This has limitations in investigating the interactive effects between existing structures and surrounding ground due to the excavation of the divergence tunnel. In this study, the complex interactive behavior of pile, the operating tunnel, and the surrounding ground according to horizontal offsets between the two adjacent tunnels was quantitatively analyzed based on conditions diverged from operating tunnel in urban areas. The effects on ground structures confirmed by analyzing the ground surface settlements, pile settlements, and the axial forces of the pile. The axial forces of lining in operating tunnel investigated to estimate their impact on existing tunnel. In addition, in order to identify the deformation of the surrounding ground, the close range photogrammetry applied to the laboratory model test for confirming the underground displacements. Two-dimensional finite element numerical analysis was also performed and compared with the results. It identified that the impact of excavating a divergence tunnel decreased as the horizontal offset increased. In particular, when the horizontal offset was larger than 1.0D (D is the diameter of operating tunnel), the impact on existing structures further reduced and the deformation of surrounding ground was concentrated at the top of the divergence tunnel.

• JSTS:Journal of Semiconductor Technology and Science
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• v.8 no.1
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• pp.32-39
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• 2008

Tunnel oxide of non-volatile memory (NVM) devices would be very difficult to downscale if ten-year data retention were still needed. This requirement limits further improvement of device performance in terms of programming speed and operating voltages. Consequently, for low-power applications with Fowler-Nordheim programming such as NAND, program and erase voltages are essentially sustained at unacceptably high levels. A promising solution for tunnel oxide scaling is tunnel barrier engineering (TBE), which uses multiple dielectric stacks to enhance field-sensitivity. This allows for shorter writing/erasing times and/or lower operating voltages than single $SiO_2$ tunnel oxide without altering the ten-year data retention constraint. In this paper, two approaches for tunnel barrier engineering are compared: the crested barrier and variable oxide thickness. Key results of TBE and its applications for NVM are also addressed.

• Proceedings of the Korean Society of Propulsion Engineers Conference
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• 2011.11a
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• pp.777-780
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• 2011

The supersonic wind tunnel is a common facility to studies the aerodynamic phenomenon around the high speed vehicle or weapon system whose operating speed is greater than sonic speed. In this study, a design procedure and selecting the components of a new supersonic wind tunnel whose nozzle exit is $125mm{\times}100mm$ is considered. An operating test of this wind tunnel is being conducted to compare the result with the design values, mach number, etc.

• Journal of the Society of Naval Architects of Korea
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• v.44 no.4
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• pp.408-416
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• 2007

This paper summarizes an experimental study on the marine propeller BPF noise. The main objective of this study is to show the worthiness of the noise measurement at the MOERI middle size cavitation tunnel and to acquire useful propeller noise data. Background noise of MOERI(Maritime and Ocean Engineering Research Institute) cavitation tunnel is experimentally analyzed. Experiment carried out in the MOERI cavitation tunnel with wake screen or dummy body, which is simulated the wake. Propeller BPF noise is measured under various operating conditions. In order to secure the reliance of measured propeller noise dada, background noise of each operating conditions are measured and analyzed. The noise characteristics are analyzed according to the operating condition.

• Proceedings of the KSR Conference
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• 2008.11b
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• pp.73-78
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• 2008

There has been need for safety monitoring systems for the social infrastructures. These infrastructures are subject to degradation over time, reduced functionality, and loss of functionality as a result of factors such as a wide variety of installation environments, natural disasters, and nearby work. Therefore, it is necessary to perform appropriate inspections, repairs, and renovations to ensure safe and efficient maintenance and operation. This paper introduces the example of the development of the safety monitoring system for operating railway tunnel. Tunnel profile measuring system using laser beam, crack gauges, accelerometer and a pluviometer were implemented to monitor the safety of a deteriorated tunnel. The measured data were transferred through wireless network and analyzed in real time. The safety criteria for tunnel stabilities and train operations are also discussed.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.2
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• pp.183-193
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• 2016

Estimation of the stability of an operating tunnel through a back analysis is a difficult concept to analyze. Specially, when a relatively thick lining is constructed as in case of a subsea tunnel, there will be a limit to the use of displacement-based tunnel back analysis because the corresponding displacement is too small. In this study, DEA is adopted for tunnel back analysis and the feasibility of DEA for back analysis is evaluated. It is implemented in the finite difference code FLAC3D using its built-in FISH language. In addition, the stability of a tunnel lining will be evaluated from the development of displacement-based algorithm and its expanded algorithm with conformity of several parameters such as stress measurements.

• Fire Science and Engineering
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• v.22 no.1
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• pp.61-67
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• 2008

This study is focused on the numerical predictions of heat and smoke exhaust characteristics in an underground subway station stopping a fire train. Various ventilation operating modes with the fan equipped the platform and tunnels are considered. Distributions of temperature, carbon monoxide and visibility at a height of 1.7 m(breath height) above the platform are analysed for different ventilation fan operation mode. The numerical results show that smoke and heat is rapidly removed through tunnel by operating the tunnels fans. We suggested that during evacuation of passengers is not completed, the ventilation system in the platform is activated. After completion of passenger evacuation tunnel fans are activated but the fans in the platform are stopped.

• 한국기계연구소 소보
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• s.10
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• pp.79-97
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• 1983

This report includes the general descriptions on the Cavitation Tunnel, newly installed at the Ship Research Station, KIMM, and also on the functions and operating procedures of the major measuring equipments. It also includes the results of the trial operation of the Tunnel and testing techniques in the Cavitation Tunnel.

• Proceedings of the KSR Conference
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• 2007.11a
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• pp.313-336
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• 2007

Unlike a conventional railway system, a high-speed rail system experiences various aerodynamic problems in tunnel sections. Trains running at a high speed in a small tunnel, when compared with the open field, face significant air pressure, resulting in reduced operating stability and fast change in pressure inside the tunnel. These phenomena further cause some unexpected problems such as the passengers onboard feeling an aural discomfort and an impulsive noise at the tunnel exit. To solve these problems, this paper introduces analysis of aerodynamic characteristics for determination of tunnel cross section. The optimum cross-section that satisfies the criteria of aural discomfort was reviewed through lots of numerical simulation analysis. Also, the pressure inside the passenger car of a train operating on Kyungbu HSR line was measured, and the pressure inside the tunnel and the micro-pressure waves at tunnel exit were measured at Hwashin 5 Tunnel. At the same time, a test of train operation model was performed and then the measurement results and test results were compared to verify that various parameters used as input conditions for the numerical simulations were appropriate.

• Proceedings of the Korean Geotechical Society Conference
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• 2005.03a
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• pp.1343-1350
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• 2005

In this study, the whole deformation conditions of domestic old tunnels and reinforcement methods for deformation tunnels were investigated and analysed, and the present conditions, occurrence cause and reinforcement methods of cavity behind the tunnel lining were investigated and analysed comprehensively. The deformation causes of domestic old tunnels could be classified in three kinds : change of earth pressure operating tunnel ground, material problem of concrete lining, mistake of design and construction. As a result of analysis, the tunnel deformation was occurred by not specific cause but various cause As a result of investigation for 455 domestic tunnel data, more than 70% of the tunnel deformation was related to leakage and the other deformation cause also accompanied leakage mostly. An applied reinforcement method was related to leakage and flood prevention measures, but application of reinforcement method for boundary area between tunnel and ground and tunnel periphery which influence on the tunnel stability was still defective. The cavity of domestic old tunnel occupied about 16% of the total tunnel length and about 68% of cavity was located in the crown of tunnel, and besides, the occurrence cause of cavity was analysed to design, construction and management cause. The filling method for cavity using filling material was comprehensively appling to cavity behind tunnel lining.