• Journal of Korean Society for Geospatial Information Science
• /
• v.17 no.1
• /
• pp.105-111
• /
• 2009

A construction can be more convenient and safer with adequate informations. Consequently, studies on collecting various informations using newest surveying technology and applying these informations to a construction have been making progress recently. Digital images are easy to obtain and contain various informations. Therefore, with the recent development of image processing technology, the application field of digital images is getting wider. In this study, we proposed to use a fisheye lens camera in underground construction sites, especially tunnels, to overcome inconvenience in photographing with general lens cameras. A program for mapping the surface of a tunnel and making a mosaic image is also developed. This mosaic image can be applied to observe and analyze abnormal phenomenons on tunnel surface like cracks, water leakage, exfoliates, and so on.

• Journal of the Korean Society of Safety
• /
• v.9 no.4
• /
• pp.92-102
• /
• 1994

NATM as method of tunneling has been applied to construction of domestic subway, roads, rail way, water way etc. Accordingly we have NATM's many drafts and constructional results, but many problems and accidents have occurred under construction of tunnel using NATM for shortage of technical data, poorness of constructional improvement, systemic inconsistency etc. Especially, everyone was shocked at Gupo's train wrecking accident lately. The purpose of this thesis is presentation of means for settling technical problems, by looking into Gupo's train wrecking accident and home records that applying NATM in tunneling failed, to minimize future safety accidents we find that the general problems of home fifteen sites haying occured accidents is badly geological survey, nonconfirmation of base rock's state, formal measuring management, shortage of specialists, systemical discrepancy and that disregarding NATM's rules makes general problems. The results of this study are summarised as follows ; 1. We advise repletion of design standards to practice crosshole test for confirming connected rock base on vertical section of tunnel. 2. We advise to practice pre-boring and pre-grouting for a weak layer difficult in applying NATM. 3. We advise systemic improvements that field servicer can construct tunnel of his own free will considering base rock's state at tunnel. 4. We advise that specialist, who can make a conduct and supervise above mentioned items as well as measuring managements, should be posted at field.

• Geomechanics and Engineering
• /
• v.21 no.2
• /
• pp.153-164
• /
• 2020

Tunnel excavation in shallow soft ground conditions of urban areas experiences inevitable surface settlements that threaten the stability of nearby infrastructures. Surface settlements during shield TBM tunneling are related to a number of factors including geotechnical conditions, tunnel geometry and excavation methods. In this paper, a database collected from a construction section of Hong Kong subway was used to analyze the correlation of settlement-inducing factors and surface settlements monitored at different locations of a transverse trough. The Pearson correlation analysis result revealed a correlation between the factors in consideration. Factors such as the face pressure, advance speed, thrust force, cutter torque, twin tunnel distance and ground water level presented a modest correlation with the surface settlement, while no significant trends between the other factors and the surface settlements were observed. It can be concluded that an integrated effect of the settlement-inducing factors should be related to the magnitude of surface settlements.

• Proceedings of the Korean Society for Rock Mechanics Conference
• /
• 1995.03a
• /
• pp.1-26
• /
• 1995

Key aspects of the Norwegian Method of Tunnelling (NMT) are reviewed. These include a predictive method of support design using the six-parameter Q-system of rock mass characterisation. The rock mass rating or Q-value is updated during tunnel driving. The designed tunnel support generally consists of wet process, steel fibre reinforced shotcrete combined with fully grouted, untensioned rock bolts, Even in poor rock conditions S(fr) + B usually acts as the final rock reinforcement and tunnel lining. Since it is a drained lining, it is very economic compared to cast concrete with membranes. Light, free-standing steel liners are used to prevent water affecting the runnel environment. Rock mass conditions, and hence lining design and cost estimation can be assessed by careful use of seismic surveys. Relationships between the P-wave velocity, the rock mass deformation modulus and the Q-value have recently been established, where tunnel depth, rock porosity and the uniaxial compression strength of the rock are important variables. The rock mass modulus estimate, and simple index testing of the joints, provide the key input which joints are discretely represented (either in two dimensions with the UDEC code or in three dimensions with the 3DEC code) is generally favoured compared to continuum analysis. The latter may give a misleading impression of uniformity and deformations tend to be understimated. Q-system NMT designs of S(fr) + B (fibre reinforced shotcrete and bolting) are numerically checked and adjustments made to bolt capacities and shotcrete thickness if overloading is evident around the modelled profile.

• Geomechanics and Engineering
• /
• v.25 no.1
• /
• pp.17-30
• /
• 2021

This paper develops a convenient approach for deterministic and probabilistic evaluations of tunnel face stability using support vector machine classifiers. The proposed method is comprised of two major steps, i.e., construction of the training dataset and determination of instance-based classifiers. In step one, the orthogonal design is utilized to produce representative samples after the ranges and levels of the factors that influence tunnel face stability are specified. The training dataset is then labeled by two-dimensional strength reduction analyses embedded within OptumG2. For any unknown instance, the second step applies the training dataset for classification, which is achieved by an ad hoc Python program. The classification of unknown samples starts with selection of instance-based training samples using the k-nearest neighbors algorithm, followed by the construction of an instance-based SVM-KNN classifier. It eventually provides labels of the unknown instances, avoiding calculate its corresponding performance function. Probabilistic evaluations are performed by Monte Carlo simulation based on the SVM-KNN classifier. The ratio of the number of unstable samples to the total number of simulated samples is computed and is taken as the failure probability, which is validated and compared with the response surface method.

• Journal of the Korean Institute of Telematics and Electronics
• /
• v.23 no.1
• /
• pp.65-73
• /
• 1986

Experiment have been conducted about thin oxide characteristics according to O2/N2 ratio needed for EEPROM cell fabrication. As a result, we think that there is no problem even if we grow oxide layer with large O2/N2 ratio and short exidation time and when the water is implated by As before oxidation, the oxide breakdown field is about IMV/cm lower than that is not implanted. Especially, the thin oxide characteristic seems to be affected largely by wafer cleaning and oxidation in air. On the basis of these, tunnel type EEPROM cell is fabricated by 3um CMOS process and its characteristic is studied. Tunnel oxide thickness(100\ulcorner is chosen to allow Fowler-Nordheim tunneling to charge the floating gate at the desired programming voltage and tunnel area(2x2um\ulcorneris chosen to increase capacitive coupling ratio. For program operation, high voltage (20-22V) is applied to the control gate, while both drain and source are gdrounded. The drain voltage for erase is 16V. It is shown that charge retention characteristics is not limited by leakage in the oxide and program/erase endurance is over 10E4 cycles of program erase operation.

• Journal of the Society of Naval Architects of Korea
• /
• v.37 no.1
• /
• pp.26-39
• /
• 2000

This paper presents the influence of Reynolds number on propeller open-water performance at the towing tank and the cavitation tunnel for series propellers(No. of blade=4, $0.3{\leq}A_E/A_O{\leq}0.75,\;0.5{\leq}P/D{\leq}1.1$). It is shown that the Reynolds number recommanded by 15th and 17th ITTC is not large enough to obtain reliable P.O.W. test results and then the suitable test conditions for the both facilities is suggested. The correlation of the propeller open-water characteristics at the cavitation tunnel and the towing tank is described and a correlation factor $\kappa$ is deduced from those test results. The viscous effect of the flow around the propeller shaft on the propeller characteristics is investigated from the velocity measurement by Laser Doppler Velocitimetry(L.D.V.). The measured velocity distribution shows that viscous flow effect is not negligible.

• Fire Science and Engineering
• /
• v.16 no.1
• /
• pp.66-76
• /
• 2002

This paper includes new nozzle design, basic design factors of water mist system that minimize a thermal damage of cable causing business interruption and applying underground utility tunnel. A underground concrete structure (2.5 m(H)$\times$2.5 m(W)$\times$25 m(D)) is constructed in order to test a nozzle performance. Under the designing fire scenario, critical thermal damage of cable sheath ($400^{\circ}c$) reached within a 2 minutes with unsuppressed fire, but type 1 nozzle (SMD 470 $\mu{m}$) and type 2 nozzle (SMD 650 $\mu{m}$) control cable temperature below $400^{\circ}c$. A system performance and fundamental design factors; K factor, flow rate, spray angle, size distribution, nozzle pressure, spray density are analyzed and proposed for system optimization.

• Solar Energy
• /
• v.15 no.3
• /
• pp.59-73
• /
• 1995

The thermal analysis is accomplished with the route for the underground power transmission system which adopts the water pipe cooling with trough in tunnel. As a result, in case of a cooling system based on a refrigerator, the optimum condition for the flow rate of cooling water and the air velocity are calculated as the $2{\sim}3{\ell}/s/pipe$ and $1{\sim}2m/s/fan$, respectively. On the other hand, in case of cooling tower the optimum condition for them are calculated as the $2{\sim}3{\ell}/s/pipe$ and 6 m/s/fan, respectively. But the cooling system based on a cooling tower has the problem of enlarging the size of cooling fan and suppressing the labor of operator in tunnel. Therefore, to meet all the cooling conditions for a given cooling section, the cooling system based on a refrigerator is more acceptable.

• Tunnel and Underground Space
• /
• v.13 no.3
• /
• pp.196-206
• /
• 2003

In order to investigate the workability of Raise Boring Machine(RBM) such as utilization, penetration rate and advance rate, a vertical shaft of 98 m in length and 3.05 m in diameter was constructed in the layer of conglomerate by using the RBM in this study. In addition, field data from tow different construction sites including water-pump power plant tunnel, roadway tunnel and mining tunnel by RBM were collected and analyzed. The results show that the average weekly bored length is 19.3 m and its average utilization is between 54.3 % and 75.1 % very higher than that of the TBM(Tunnel Boring Machine). It also turns out that the bit force increases linearly with respect to the increase of the RPM(revolution per minute) of RBM. However, the net penetration rate decreases with the increase of bit force, RPM of RBM and depth of shaft. The findings of this study can be used to provide the useful information for the design of shaft and the selection of RBM.