• Journal of Korean Tunnelling and Underground Space Association
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• v.25 no.5
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• pp.357-371
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• 2023

In cable tunnel construction using TBM, the vertical shaft is an essential structure for entrance and exit of TBM equipment and power lines. Since a shaft penetrates the ground vertically, it often encounters rock mass. Blasting or rock splitting methods, which are mainly used to the rock excavation, cause public complaints due to the noise, vibration and road occupation. Therefore, mechanical excavation using vertical shaft excavation machine are considered as an alternative to the conventional methods. However, at the current level of technology, the vertical excavation machine has limitation in its performance when applied for high strength rock with a compressive strength of more than 120 MPa. In this study, the potential utilization of waterjet technology as an excavation assistance method was investigated to improve mechanical excavation performance in the hard rock formations. Rock cutting experiments were conducted to verify the cutting performance of the abrasive waterjet. Based on the experimental result, it was found that ensuring excavation performance with respect to changing in ground conditions can be achieved by adjusting waterjet parameters such as standoff distance, traverse speed and water pressure. In addition, based on the relationship between excavation performance, uniaxial compressive strength and RQD, it was suggested that excavation performance could be improved by artificially creating joints using the abrasive waterjet. It is expected that these research results can be utilized as fundamental data for the introduction of vertical shaft excavation machines in the future.

• Proceedings of the Korean Society of Marine Engineers Conference
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• 2012.06a
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• pp.175-175
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• 2012

Proper shaft alignment is one of the most important actions during the design of the propulsion system. The stiffness of recently designed marine propulsion shafting has been increasing remarkably, whereas hull structures have become more likely to deform as a result of optimized design of the scantlings and the high tensile steel. Therefore, to obtain the optimum status in shafting alignment at the design stage, it is strongly recommended that the change of bearing reaction force depending on ballast/load condition, the bending moment force occurred by propeller thrust, elastic deformation of bearing occurred by vertical load of shaft mass and etc., should be considered. This paper dealing with introduction of shaft alignment concerning long shaft for high speed vessel and review its reliability evaluation theoretically.

• KIEAE Journal
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• v.13 no.1
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• pp.75-81
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• 2013

The balcony of our apartment building consists of unique construction similar to double skin. It is announced broadly that double skin is very effective system in improvement of natural ventilation and indoor thermal environment, and outdoor sound protection. So, for the improvement of indoor climate and energy saving, many peoples studied about environmental performance of our balcony construction. This study focus on shaft box facade, special form of box window construction. It consists of a system of box window with continuous vertical shafts that extend over a number of stories to create a stack effect. Proto-type was decided by analyzing various types of exiting apartments. Shaft box type balcony was created by setting up shaft space at a part of balcony. Air flow and contribution of air temperature were simulated, performance of shaft box type balcony was compared with existing balcony. Finally, we confirmed that shaft box type balcony has many possibility for improvement of indoor environment.

• Journal of Korean Tunnelling and Underground Space Association
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• v.15 no.6
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• pp.559-570
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• 2013

High speed railway can transport large quantity of people and commodities in a short time and has become one of the most desirable and environmentally friendly transportation. However, it is hard to have a complicated route for high speed railways, construction of tunnels is essential to pass through a mountain area. When a high speed train enters a tunnel, pressure wave is created in a tunnel and the wave causes micro pressure wave and discomfort to passengers. In order to alleviate pressure wave in a tunnel, constructing a vertical shaft is one of the most efficient ways. This study represents a numerical analysis module, which takes into account the effect of a vertical shaft in a tunnel. The module can be used in a numerical program (TTMA) specialized for aerodynamics in a tunnel, and it was validated by comparing numerical results with various measurements in Emmequerung tunnel and results from numerical analysis using Fluent.

• Journal of KSNVE
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• v.8 no.5
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• pp.922-928
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• 1998

This paper presents the automatic alignment measuring system for improving the accuracy and working time of alignment of large vertical hydraulic pump turbine. It is general practice that rotating shaft should run within acceptable vibration limit. In order to obtain better run-out data of multi-stage rotor, careful and accurate alignment approach must be established. Generally, present alignment procedure are required several iterative works and so many manpower. Therefore, the new system has been developed using a vector calculation algorithm, laser sensor and data acquisition devices. As a result of appling to actual machines, it is confirmed that manpower is saved up to an average 90%.

• Proceedings of the Korean Society of Precision Engineering Conference
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• 2002.10a
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• pp.841-844
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• 2002

The vertical impact crusher is the machine which could produce artifical sand similar to natural aggregates in the site of guarry and pits. FEM was used to analyse the stress and strength of the machine at high rotational speed. The test specimen was made from the same material as the shaft and tension tests were conducted. The shaft under extreme conditions was analysed to determine maximum stress level and its location from the results. The maximum level of stress and its location could be predicted.

• Transactions of the Society of Information Storage Systems
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• v.10 no.1
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• pp.23-26
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• 2014

In this paper, we present a novel approach for tuning the resonant frequency of torsionally driven vertical comb actuators. The tuning unit composed of thermal actuator, scissor mechanism and V-shape shaft enables continuous and reversible resonant frequency tuning. The proposed method is based on the stiffness alteration of the V-shape shaft. It is experimentally verified that the resonant frequency of the torsional microscanner is shifted up to 1.59 kHz from 1.51 kHz showing the maximum tuning ratio of 5.29%.

• Proceedings of the Safety Management and Science Conference
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• 2004.05a
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• pp.211-220
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• 2004

The vertical impact crusher is the machine which could produce artifical sand similar to natural aggregates in the site of guarry and pits. FEM was used to analyse the stress and strength of the machine at high rotational speed. The test specimen was made from the same material as the shaft and tension tests were conducted. The Shaft under extreme conditions was analysed to determine maximum stress level and its location from the results. The maximum level of stress and its location could be predicted.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.4
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• pp.717-729
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• 2018

Considering the stability of the ground in the process of excavation design is essential because there is a risk of basal heave due to the load of the surrounding ground during the vertical excavation. However, calculation of the factor of safety for basal heave should be performed with two-dimensional equation, and the equation cannot reflect three-dimensional shape of vertical excavation. In this study, an equation for factor of safety for the basal heave was proposed with considering the effect of three-dimensional shape. It is confirmed that the equation can more appropriately reflect the basal heave stability 3D circular vertical excavation than the existing equation. Using the equation proposed in this study, it is possible to derive an appropriate factor of safety according to the 3D excavation shape during the circular vertical shaft excavation.

• Journal of Korean Tunnelling and Underground Space Association
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• v.11 no.2
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• pp.117-129
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• 2009

Several researches have been done to estimate the earth pressure on a vertical circular shaft considering three dimensional arching effect and verified them by conducting model tests. However, any equation suggested so far is not applicable in case of multi-layered soils and/or C-${\phi}$ soils. In this study, new equation for estimating the earth pressure acting on the vertical shaft in c-${\phi}$ soils is proposed. A parametric study is performed to investigate the significance of the cohesion when estimating the coefficient of earth pressure in C-${\phi}$ soils and estimating earth pressures in vertical shafts. A method which can estimate the earth pressure on vertical shafts in layered soils is also proposed by assuming a failure surface in layered soils and using the modified equation. This paper is Part I of companion papers focusing on the theoretical aspect of model developments; the experimental verification will be made in Part II.