• Proceedings of the KSR Conference
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• 2005.05a
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• pp.722-725
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• 2005

Recently, ground-borne noise and vibration generated by underground transit system has been recognized as an important environmental problem. This study reviews several of the improved procedures that have been used to predict ground-borne vibration. At first, ground stiffness profile is examined by SASW test which is the most reasonable surface wave test. It is very important to acquire the exact ground stiffness profile at ground response analysis. At second, the train loading to act roadbed is calculated by using the real measured phase angle data. In finite element analysis, averaged acceleration method, infinite element, Rayleigh damping and 2-dimensional wave propagation analysis is performed.

• Proceedings of the Korean Society for Noise and Vibration Engineering Conference
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• 2011.10a
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• pp.602-606
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• 2011

In this study, operational vibration experiment and analysis have been conducted for the 4-blade small vertical-axis wind turbine (VAWT) including the effect of tower elastic behavior. Computational structural dynamics analysis method is applied to obtain Campbell diagram for the VAWT with elastic tower. An open type wind-tunnel is used to change and keep the wind velocity during the ground test. Equivalent reduced elastic tower is supported to the VAWT so that the elastic stiffness effect of the tower can be reflected to the present vibration experiment. Various excitation sources with aerodynamic forces are considered and the dominant operating vibration phenomena are physically investigated in detail.

• Tunnel and Underground Space
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• v.8 no.4
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• pp.342-350
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• 1998

In this study, fracture network in rock mass was interpreted using borehole wall images obtained by televiewer. The orientation and JRC value of major joint set were evaluated adopting image analysis techniques, of which process were written in macro-program code. As linking JRC to joint stiffness using Barton-Bandis model, fracture network map was produced for application to jointed rock modelling in numerical analysis of underground structure.

• Journal of the Korean Geotechnical Society
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• v.21 no.3
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• pp.87-98
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• 2005

When a tunnel is excavated below groundwater table, the groundwater flows into the excavated wall of tunnel and seepage forces are acting on the tunnel wall. The ground reaction curve is defined as the relationship between internal pressure and radial displacement of tunnel wall. Therefore, the ground reaction curve is significantly affected by seepage forces. In this study, the theoretical solutions of ground reaction curves were derived for both the dry condition and the seepage forces. The theoretical solutions derived were validated by numerical analysis. The ground reaction curves with the support characteristic curve were also analyzed in various conditions of groundwater table. Finally, the theoretical solutions of the ground reaction curve derived in this study can be utilized easily to determine the appropriate time of support systems, the stiffness of support system and so forth for the reasonable design.

• Journal of Korean Tunnelling and Underground Space Association
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• v.9 no.3
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• pp.299-307
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• 2007

In this study, a new concept for simulating a physical damage of tunnel shotcrete lining due to a long-term chemical deterioration has been proposed. It is known that the damage takes place mainly by internal cracks, reduction of stiffness and strength, which results mainly from volume expansion of the lining and corrosion of cement materials, respectively. This damage mechanism of shotcrete lining appears similar in most kinds of chemical reactions in tunnels. Therefore, the mechanical deterioration mechanism induced by a series of chemical reactions was generalized in this study and mathematically formulated in the framework of thermodynamics. The numerical model was implemented to a 3D finite element code, which can be used to simulate behaviour of tunnel structures undergoing external loads as well as chemical deterioration in time. A number of illustrative examples were given to show a feasibility of the model in tunnel designs.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.1
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• pp.99-118
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• 2018

Recently, the limit state design method in the design of the structure is in global trend, but it is limited to a few structures in Korea. Since the introduction of the limit state design method has recently been attempted for tunnels, which are the main underground structures, it is surely necessary to understand the latest limit state design method. Therefore, based on the recently published AASHTO LRFD Road Tunnel Design and Construction Guide Specification (2017), structural load factors and load combinations were reviewed, and various factors which should be applied for the review of structures have been analyzed. In this study, utility tunnel section and subway tunnel sections used in Korea were analyzed by the limit state design method, and we have analyzed the direction of application of limit state design method through studying the tendency of member force by various influential factors such as ground conditions, load modifier and joint stiffness.

• Journal of Acupuncture Research
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• v.19 no.6
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• pp.61-66
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• 2002

Objective : Carpal tunnel syndrome has gained increasing attention and acceptance as a significant cause of peripheral neuropathy, since it was first reported in 1836. The purpose of this study is to inspect the effect of oriental medical treatment on Carpal tunnel syndrome patients who is not come under surgical decompession. Methods : 20 patients who visited Won-Kwang University Hospital during the period from January 1998 to May 2000 were analysed for clinical manifestations. Results : 1. Among 20 patients, 3 were male and 17 were female. 2. The syndrome occurred on the right side in 5 patients, on the left side in 0 patients, and on both 15 patients 3. The most of causes were overwork. 4. Numbness was the most common symptom followed by night pain, paresthesis, morning stiffness, puffiness and resting pain 5. Among 20 patients, 12 were Tinel's sign positive, 16 were Phalen's test positive Conclusions : When the symptom is mild and duration is short, conservative treatment is effetive, but when neurological deficit is prominent and conservative treatment is not effective, surgical decompession is indicated. We treated 19 among 20 cases of the patients which Carpal Tunnel syndrome. We achieved effective results.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.1
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• pp.83-94
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• 2016

Utility tunnels have been employed in Korea since the 1970s and start to make trouble with structural safety and serviceability. Recently, tunnel enlargement has consequently been proposed due to the impending problems. However there are little study on box type utility tunnels except traffic tunnels. A 2D finite element analysis was conducted to evaluate ground behavior which depends on enlargement size and stiffness by one-side enlargement of the utility tunnel. Settlement scale increased with larger enlargement size and less stiff ground conditions. The observed settlement characteristics due to enlargement are similar to that suggested by Clough & Schmidt (1981). The settlement width is more affected by enlargement size than ground condition.

• Journal of the Korean Geotechnical Society
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• v.19 no.4
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• pp.167-178
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• 2003

Damage and overbreak of the remaining rock induced by blasting can not be avoided during tunnel construction which may result in either short-term or long-term tunnel instability. Therefore, in this paper, a methodology to take into account the effect of blast-induced damage in tunnel stability assessment is proposed. Dynamic numerical analysis was executed to evaluate damage and overbreak of the remaining rock for the most common blasting pattern in road tunnel. Rock damage was quantified by utilizing the damage variable factor which is adopted proposed in continuum damage mechanics. The damaged rock stiffness and the damaged failure criteria are used to consider the effect of rock damage in tunnel stability analysis. The damaged geological strength index of the damaged rock was newly proposed from the relationship between deformation modulus and geological strength index. Also the Hoek-Brown failure criteria of the damaged rock was obtained using the damaged geological strength index. Analysing the tunnel stability with the consideration of the blast-induced damage of remaining rock, it was found that the extend of plastic zone and deformation increased compared to the undamaged rock. Therefore the short-term or long-term tunnel stability will be threatened when the rock damage from blasting is ignored in the tunnel stability analysis.

• Tunnel and Underground Space
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• v.15 no.5 s.58
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• pp.330-337
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• 2005

Apart from the geometric features of the rock joints, the shear characteristics of rock mass subject to shear force are also significantly affected by the boundary conditions in the neighborhood of the rock mass. The boundary conditions of the rock mass can be classified into 4 categories according to the stress state of the rock joint, of which the constant normal load (CNL) is the most used for shear test and produces the lowest shear strength and different behavior. In this study, the shear behavior under constant normal stiffness condition was able to replicated by the graphic method normalized by the test results under constant normal stress condition.