• Journal of Korean Tunnelling and Underground Space Association
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• v.5 no.2
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• pp.199-207
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• 2003

Tunnel modelling in the field of geotechnical engineering essentially requires models of tunnelling machines and the simulation of tunnelling processes to clarify the detailed behaviour of tunnel construction. Modern advanced mechatronics, including construction processes, machinining and control technologies, are making it possible to fabricate such models. These technologies, however, are essentially developed in a gravity field condition and are needed to examine in a 1g or cenrifuge field condition. This paper presents the simulation method for tunnelling processes and the design method for tunnelling machines with special reference to the problem of earth pressure acting on the lining of a shield tunnel. The paper then introduces and verifies the design method for tunnelling machines in the 1g field by means of checking the reproduceability of experiment data and their comparison with data in the field.

• Proceedings of the Korean Geotechical Society Conference
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• 2001.03a
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• pp.493-500
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• 2001

The construction of bored tunnels in soft ground inevitably causes ground movements. In the urban environment these may be of particular significance, because of their influence on buildings, other tunnels and services. The prediction of ground movements and the assessment of the potential effects on the structures is therefore an essential aspect of planning, design and construction of a tunnelling project in the urban environment. In this study, to minimize the effect of tunnelling-Induced ground movements on the adjacent structures, a system for tile settlement risk management was developed. The GIS based risk assessment system for adjacent structures developed in this study consists of several modules such as building information module, settlement evaluation module, potential risk assessment module for adjacent structures, and analysis module for monitoring data. This system focuses on controlling and managing construction processes that may lead to settlement In the surrounding buildings and can contribute to producing the optimum technical and economic design.

• Journal of Korean Tunnelling and Underground Space Association
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• v.3 no.2
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• pp.23-32
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• 2001

Rock masses are usually discontinuous in nature, as a result of various geological processes they have underdone and they contain rock joints and bridges. Crack propagation and coalescence processes mainly cause rock failures in tunnels. In this study, we focused on the crack initiation, propagation and coalescence process of rock materials containing two pre-existing open cracks arranged in different geometries. During uniaxial compression, wing crack initiation stress, wing crack propagation angle, and crack coalescence stress of Diastone gypsum and Yeosan Marble specimens were examined. And crack initiation, propagation, and coalescence processes were observed. Shear, tensile and mixed (shear+tensile) types of crack coalescence occurred. To compare the experimental results with Ashby & Hallam model, crack coalescence stress was normalized and it generally agreed with the experimental results.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.6
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• pp.667-681
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• 2012

In general, risk management consists of a series of processes or steps including risk identification, risk analysis, risk evaluation, risk mitigation measures, and risk re-evaluation. In this paper, potential risk factors that occur in shield TBM tunnels were investigated based on many previous case studies and questionaries to tunnel experts. The risk factors were classified as geological, design or construction management features. Fault Tree was set up by dividing all feasible risks into four groups that associated with: cutter; machine confinement; mucking (driving) and segments. From the Fault Tree Analysis (FTA), 12 risk items were identified and the probability of failure of each chosen risk item was obtained.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.5
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• pp.773-786
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• 2018

In this paper, viscosity features of sealant (bentonite-cement slurry), which is used for umbrella arch method in tunnel, were studied. The sealant must secure optimal strength and capacity for the waterproof and stabilization of borehole as well as to satisfy groutability. In this study, the variation of viscosity was measured with different mixing processes. With an increase of initial mixing period with water and bentonite mixture, the required time for the rapid increase of viscosity of the sealant is shorten. With increase of mixing period, the possibility of swelling of bentonite will increases and this can lead increase of the viscosity of the mixture. In addition, the behaviors of sealant vary with a drastic increase of the viscosity: thixotropy and rheopexy. Furthermore, the bentonite/water mixing period influences on the bleeding features of the sealant. Further study is required to introduce the guideline, which can be applicable in the field in the aspect of required capacity of the sealants and mixing processes of the ingredients.

• Journal of Korean Tunnelling and Underground Space Association
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• v.24 no.2
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• pp.183-192
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• 2022

Function and performance degradation in tunnel structure can cause road's function loss, proactive maintenance is needed to prevent the initial damage from progressing to intensified damage. Inspection and diagnosis are implemented in accordance with regulations, but it does not fully reflect maintenance processes such as inspection and diagnosis, planning rehabilitation and carrying out. It was carried out for 5,540 cases inspection and diagnosis result in 1,728 tunnels was analyzed to suggest rational maintenance plan in this study.

• Journal of Power System Engineering
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• v.5 no.1
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• pp.73-79
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• 2001

정전기력을 이용하는 마이크로가속도계 센서는 단결성 실리콘 SOI(Silicon On Insulator) 웨이퍼의 기판에 절전재료 적층과 등방성 및 이방성 부식공정으로 제작한다. 마이크로가속도 센서 개발에는 3차원 미소구조체의 제작공정에서 가열 및 냉각공정의 온도구배로 야기되는 포핑업과 같은 열변형 해석이 최적 형상설계에 중요한 요건이다. 본 연구에서는 양자역학적 현상인 턴널링전류 원리로 승용차 에어백의 검침부 역할을 하는 마이크로가속도 센서의 제조공정에서 소착현상을 방지하는 부가 비임과 턴널갭의 FIB 절단가공과 백금 적층공정의 열적 거동을 해석한다. 마이크로머시닝 공정에서 온도의존성을 고려하여 연성해석하고 유한요소법의 상용코드인 MARC K6.1로 분석한 결과를 단결정 실리콘 웨이퍼로 가공하는 마이크로가속도 센서의 최적공정 및 형상설계를 위한 기초자료로 활용될 수 있을 것으로 기대된다.

• Journal of Korean Tunnelling and Underground Space Association
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• v.14 no.1
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• pp.79-91
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• 2012

A curved fiber reinforced polymer (FRP) panel is produced with a certain width depending on allowances of manufacturing processes and facilities. An targeted arch-shaped structure could be built by sequential connection of series of the FRP panels. The connection manner between the FRP panels could be given by chemical treatment, mechanical treatment and hybrid method. Among those, the connection between the panels by chemical treatment is commonly adopted. Therefore, For an optimized design of the connected part between FRP pannels, a number of direct shear tests have been undertaken in terms of a number of parameters: surface treatment conditions, bonding materials, etc.. As results, surface grinding condition by sand paper or surface treatment by sand blasting appear properly acceptable methods, and epoxy and acryl resins are shown to be effective bonding materials for the purpose in this study.

• Journal of Korean Tunnelling and Underground Space Association
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• v.23 no.5
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• pp.315-323
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• 2021

Tunnel is the most energy-consuming structure in road due to the characteristic of using artificial lighting during day and night. Therefore, tunnel lights are being replaced by LED lamp that have advantages with respect to low power consumption. The best use of social overhead capital can be expected by considering the life cycle cost, because to tunnel structures are accompanied by a series of medium-to-long-term and continuous processes of replacing auxiliary facilities. In this study, the saving effect by LCC analysis was quantitatively analyzed by replacing tunnel light sources from high-pressure sodium lamps to LED lamps. The effect of reducing the replacement cycle by increasing the life of the lamps and the resulting maintenance cost is very significant, on replacing tunnel lighting light sources with LED lamp.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.6
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• pp.1161-1175
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• 2018

An unexpected event could be easily followed by a large secondary accident due to the limitation in sight of drivers in road tunnels. Therefore, a series of automated incident detection systems have been under operation, which, however, appear in very low detection rates due to very low image qualities on CCTVs in tunnels. In order to overcome that limit, deep learning based tunnel incident detection system was developed, which already showed high detection rates in November of 2017. However, since the object detection process could deal with only still images, moving direction and speed of moving vehicles could not be identified. Furthermore it was hard to detect stopping and reverse the status of moving vehicles. Therefore, apart from the object detection, an object tracking method has been introduced and combined with the detection algorithm to track the moving vehicles. Also, stopping-reverse discrimination algorithm was proposed, thereby implementing into the combined incident detection processes. Each performance on detection of stopping, reverse driving and fire incident state were evaluated with showing 100% detection rate. But the detection for 'person' object appears relatively low success rate to 78.5%. Nevertheless, it is believed that the enlarged richness of image big-data could dramatically enhance the detection capacity of the automatic incident detection system.