• Journal of Korean Tunnelling and Underground Space Association
• /
• v.17 no.6
• /
• pp.575-586
• /
• 2015

In NATM tunnel, the Ground-Lining Interaction model(GLI model) had been proposed a one of the numerical analysis as the ground load estimation method of the concrete lining. But this model was not applied with the interface mechanism between the ground and the support member or concrete lining. Therefor in this study, it is implemented as a model for closer than actual states that the interface element applied to the existing GLI model. And the modified GLI formula is proposed with the ground load estimation that is from the numerical results for each ground and rock cover conditions. Based on the numerical results, the ground load acting on concrete lining is reduced to ave. 88~106% in case of IV ground condition and ave. 47~57% in case of weathered soil condition comparing with the existing GLI model. It can be anticipated that the results obtained from this study can be applied to an estimation of the ground load on the concrete lining modeled like as real states, consistent and economical design.

• Geomechanics and Engineering
• /
• v.19 no.6
• /
• pp.485-498
• /
• 2019

Pre-tensioned rock bolts can be classified into fully anchored, lengthening anchored and point anchored bolts based on the bond length of the resin or cement mortar inside the borehole. Bolts in varying anchoring methods may significantly affect the supporting effect of surrounding rock around a tunnel. However, thus far, the theoretical basis of selecting a proper anchoring method has not been thoroughly investigated. Based on this problem, 16 schemes were designed while incorporating the effects of anchoring length, pretension, bolt length, and spacing, and a systematic numerical experiment was performed in this paper. The distribution characteristics of the stress field in the surrounding rock, which corresponded to various anchoring scenarios, were obtained. Furthermore, an analytical approach for computing the active and passive strengthening index of the anchored surrounding rock is presented. A new fully anchoring method with pretension and matching technology are also provided. Then, an isolated loading model of the anchored surrounding rock was constructed. The physical simulation test for the bearing capacity of the model was performed with three schemes. Finally, the strengthening mechanism of varying anchoring methods was validated. The research findings in this paper may provide theoretical guidelines for the design and construction of bolting support in tunnels.

• Journal of Korean Tunnelling and Underground Space Association
• /
• v.14 no.6
• /
• pp.595-606
• /
• 2012

Utilization of fiber reinforced polymer(FRP) material has been increased to solve construction material problems such as corrosion, etc. However, there are still many problems in using a linear-shaped FRP material for a tunnel structure with curved section. In this study, the loading tests were performed on the curved FRP-concrete composite material to evaluate its behavior as tunnel support. These tests were based on the result from preliminary numerical analysis on FRP-concrete composite material. Also, additional numerical analysis considering interface characteristics between FRP and cement-concrete was conducted to compare the result of loading test on FRP-concrete composite material. From the results of the loading test and numerical analysis, the analysis method suggested from this study is reasonable to evaluate the mechanical behavior of FRP-concrete composite material.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.35 no.11
• /
• pp.964-972
• /
• 2007

Wind turbine experiment was carried out for the horizontal axis wind turbine with the aerodynamically optimized blade. From the comparison of aerodynamic performance between upwind and downwind type wind turbine rotor, the measured torque fluctuation of the latter is larger than that of the former. This phenomenon is owing to the interaction of wake generated from support column and blades. The wind turbine model satisfies the design condition in that the measured result of the power coefficient at zero pitch angle shows maximum peak at the designed tip speed ratio, λ = 6. It also shows that the decrease in aerodynamic power due to negative pitch change is more sensitive than that of the same positive pitch change.

• The Journal of Engineering Geology
• /
• v.17 no.4
• /
• pp.555-566
• /
• 2007

In general, RMR classification system is used for the support design of a tunnel. Face mapping during excavation and RMR-based rock classifications are conducted in order to provide information for complementary changes to preliminary survey plans and for continuous geological estimations in direction of tunnel route. Although they are ever so important, there are not enough time for survey in general and sometimes even face mapping is not available. Linear regression analysis for the estimation of mediating RQD and condition of discontinuities, which require longer time and more detailed observation in RMR, was performed and optimum regression equations are suggest as the result. The geological data collected from tunnels were analyzed in accordance with three rock types as sedimentary rock, phyllite and granite to see geological effects, generally not been considered in previous researches. Parameters for the regression analysis were set another RMR factor.

• Journal of KIBIM
• /
• v.1 no.1
• /
• pp.6-12
• /
• 2011

BIM(Building Information Modeling) technologies are the most effective for the maintenance of infrastructures because they provide information sharing througout the life-cycle of structures and support close communication between different project stages. Systematic and well-organized data play a fundamental role for the effective maintenance of subway tunnel. In this paper, 3D information models for maintenance of BIM-based subway tunnel structures are developed. Standard classifications for the maintenance and construction information classification system were adopted. A classification system based on construction information classification system was built considering procedures of maintenance work. It provides optimization and standardization of the work flow for the maintenance of subway structures by applying information modeling processes instead of the current maintenance practices. It can effectively reduces the life cycle cost and time for the maintenance. The proposed system can be utilized for the maintenance history management to enhance current maintenance system.

• Journal of the Korean GEO-environmental Society
• /
• v.9 no.5
• /
• pp.29-36
• /
• 2008

The shotcrete is a NATM technique as a major tunnel support for ground stability after tunnel excavation. Instead of a general concrete lining method, it is a trend for curtail of construction periods and reduction of construction expenses that required to use of the permanent shotcrete lining. This high-strength shotcrete is required to use as a permanent shotcrete lining. This brought out the solution of environmental pollution and harmfulness to human. Accordingly, in this study specimens for strength measurement were made to develop shotcrete possible to develop materials in early with cement mineral accelerator as NATM method construction. It was compared with existing shotcrete material, unconfined compression test, flexural strength test, antiwashout underwater test were experimented. The fish poison test was experimented to evaluate an influence of environment. As a results of the test, unconfined compressive strength and flexural strength were equivalent with 28-curing day strength of existing material. An antiwashout of research subject material was revealed excellently in antiwashout Underwater test. As a results of the fish poison, an evaluation research subject material was founded more environmentally friendly than existing shotcrete.

• Journal of the Korean Society for Aeronautical & Space Sciences
• /
• v.33 no.9
• /
• pp.27-33
• /
• 2005

This research presents the influence of the base region modeling on the aerodynamic characteristics of a launch vehicle using CFD. The vicinity of a launch vehicle is divided into four zones, and four computational cases are made using these four zones. The aerodynamic coefficients are predicted for the angle-of-attack of 6 degrees and Mach numbers ranging from 0.4 to 2.86. It was found that modeling of the base region should not be neglected for the prediction of the aerodynamic characteristics of a launch vehicle in subsonic and transonic regions. It was also found that the modeling of the sting support used in the wind tunnel test is necessary to get a better agreement with the experiments.

• Korean Parent-Child Health Journal
• /
• v.18 no.2
• /
• pp.47-57
• /
• 2015

Purpose: The purpose of this study is to discover the nature from the life experience of a person with unilateral acquired blindness and his/her family after losing the eyesight and adapting in the environment and to find the meaning of life and how to solve the problem in psychosocial aspect. Methods: This study uses one of the qualitative research methods which explains how families with the unilateral acquired blind perceive blindness after experiencing it and observes how they signify it. starts with interest in lifestyles of individuals and their families and tries to understand the subjective existences of participants in accessible ways and draw the experiences after becoming one-side blind. It cyclically uses deductive verification process through inductive method and establishing hypothesis using materials. Results: According to the results of this study, unilateral acquired blindness studies, due to shattered life, they did not know what to do. Also, discomfort from struggling in a big tunnel and even will to live were found. trying to go out to the world, seeing the new world, and trying to encourage myself, strong attachment to life was shown to by saying, appeared. Each includes sub-topics such as feeling abandoned after confirmed the blindness, feeling disappointed to doctors, family, and friends, trying to live with hope, struggling in a tunnel with thinking how to live, closing the mind from the world, seeing outside the world in the midst of struggling, trying to forget the past with the will of life, having hope to live with care of family, and trying to keep the rest vision. Conclusion: Firstly, in nursing aspect for their adaptation, programs for disable people and nursing intervention focused on their families should be developed. Secondly, since it can be economic and psychological burden for their families and acquaintances, it is necessary to support the blind so that they can find fitted rehabilitation programs and come back to society. Thirdly, active participation of health care providers may influence social interest the improvement of national welfare policy for the unilateral acquired blind.

• The Journal of Korean Institute of Communications and Information Sciences
• /
• v.30 no.4B
• /
• pp.178-185
• /
• 2005

NEMO basic support is a solution that provides network mobility in the Internet topology. Yet, when multiple mobile networks are nested, this basic solution suffers ken pinball-routing and a severe routing overhead. Therefore, several solutions for route optimization in a nested mobile network have already been suggested by the IETF NEMO WG. However, the current paper proposes Regional Information-based Route Optimization (RIRO) in which mobile routers maintain a Nested Router List (NRL) to obtain next-hop information, and packets are transmitted with a new routing header called an RIRO Routing Header (RIRO-RH). We showed that RIRO had the minimum packet overhead that remained constant, irrespective of how deep the mobile network was nested, in comparison with two earlier proposed schemes - Reverse Routing Header (RRH) and Bi-directional tunnel between HA and Top-Level mobile router (BHT).