• Land and Housing Review
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• v.3 no.1
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• pp.83-88
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• 2012

In this study, physical characteristics of cement and/or concrete materials that are typically used for energy-foundation (EF) structures have been studied. The thermal conductivity and structural integrity of the cement-based materials were examined, which are commonly encountered in backfilling a vertical ground heat exchangers, cast-in-place concrete piles and concrete lining in tunnel. For this purpose the thermal conductivity and unconfined compression strength of cement-based materials with various curing conditions were experimentally estimated and compared. Hydration heat generated from massive concrete in the cast-in-place concrete energy pile was observed for 4 weeks to estimate its dissipation time in the underground. The hydration heat may mask the in-situ thermal response test (TRT) result performed in the cast-in-place concrete energy pile. It is concluded that at least two weeks are needed to dissipate the hydration heat in this case. In addition, a series of numerical analysis was performed to compare the effect of thermal property of the concrete material on the cast-in-place pile.

• Smart Structures and Systems
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• v.24 no.6
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• pp.693-707
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• 2019

This paper proposes an integrated safety assessment method that can take multiple sources data into consideration based on a data fusion approach. Data cleaning using the Kalman filter method (KF) was conducted first for monitoring data from each sensor. The inclination data from the four tilt sensors of the same monitoring section have been associated to synchronize in time. Secondly, the finite element method (FEM) model was established to physically correlate the external forces with various structural responses of the shield tunnel, including the measured inclination. Response surface method (RSM) was adopted to express the relationship between external forces and the structural responses. Then, the external forces were updated based on the in situ monitoring data from tilt sensors using the extended Kalman filter method (EKF). Finally, mechanics parameters of the tunnel lining were estimated based on the updated data to make an integrated safety assessment. An application example of the proposed method was presented for an urban tunnel during a nearby deep excavation with multiple source monitoring plans. The change of tunnel convergence, bolt stress and segment internal forces can also be calculated based on the real time deformation monitoring of the shield tunnel. The proposed method was verified by predicting the data using the other three sensors in the same section. The correlation among different monitoring data has been discussed before the conclusion was drawn.

• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.3
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• pp.377-396
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• 2019

Explosion after penetration of a warhead in an underground structure generally causes considerable displacement, breakage and extensive damage to the target. Therefore, in order to reduce the damage effect, it is required to design an underground structure protection against penetration. In this study, major factors for improvement of penetration protection performance of reinforced concrete underground structures using applied element method are divided into strength (concrete UCS) and density (concrete thickness, reinforcement layers, reinforcement diameters, reinforcement spacings). Based on these major factors, this study performed numerical analysis of simulation of dynamic response by penetrators under various conditions and analyzed the results. The results of this study are expected to be used as basis materials to improve penetration protection performance of reinforced concrete underground structures.

• Journal of the Korea institute for structural maintenance and inspection
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• v.12 no.6
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• pp.193-204
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• 2008

This paper describes laboratory experiments modelling multiple tunnel construction in soft ground. A series of small-scale model tests have been conducted at approximately 1/50 scale in order to investigate the behaviours of existing tunnels in response to the construction of new tunnels in close proximity. The model tunnels were constructed in a consolidated Speswhite Kaolin clay using a tunnelling device involving an auger type cutter within a shield. Strain gauges and LVDTs were used for instrumenting the existing tunnels. The findings obtained from the analyses of these tests were compared to the field measurements involving the reconstruction of the Northern Line London Underground Ltd. tunnels at Old street, United Kingdom. The results were also compared to the ground movement measurements obtained from a separate set of tests undertaken using the same apparatus and experimental procedures.

• Journal of Acupuncture Research
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• v.17 no.2
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• pp.187-208
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• 2000

By the activation of ovary hormone, many morphological changes occur in the epithelial cell lines and muscle cells in rat uterus. These two cells in uterus are important to the implantation of embryo, maintaining pregnancy and starting parturition. One important change associated with the morphological change of these two cells in uterus is the change on prostaglandin(PG) metabolism. Its presence and synthesis in endometriurn and myometrium in uterus affects estrous cycle and the start of embryo implantation in uterus. It also performs as an important modulator in parturition. So the abnormally weak expression of PG causes difficulty during labor and over-expression causes pre-term labor. PG biosynthesis starts from either free or liberated arachidonic acids from membrane phospholipid by phospholipase. Such arachidonic acids are converted into PG catalyzed by Cyclooxygenase. Under normal physiological condition, Cyclooxygenase-1(COX-1) having 602 units of amino acids controls the synthesis of PG. It acts as a local hormone regulating vasomodulation of blood flow, flexible muscle movement, increasing the blood permeability and contributing the protective role in preserving integrity of the stomach lining and Cyclooxygenase-2 (COX-2) is induced by the inflammation, pregnancy and increased its expression until parturition. Lipid metabolite like PG is located in uterine and expression of COX-2 increased with pregnancy. Increased expression of COX proteins in epithelial cells and myometrial cells are told to increase the muscle contractility in uterus but decreased right after the labor in rat. It is a good sign indicating that COX proteins are deeply related to the start of labor. Currently, Several studies report the use of PG and COX-2 inhibitor as medication for controlled abortion or to prevent pre-term labor but they entail various side-effects. Our study proposed to suggest use of acupuncture as an another mediator to control abortion or pre-term labor without causing unnecessary side-effects by those medicines. Two acupuncture sites, LI-4 & SP-6 were selected due to their known efficacy. From the immunohistochemical staining of COX-2, normal expression of COX-2 protein in nonpregnant SD rat's uterus revealed that COX-2 protein was primarily detected in the lumina epithelial lining and in the epithelial cell lining contacting the stromal cells. High resolution optical microscopic scanning revealed distinguishable staining in the myometrial mucosa. LI-4 acupuncture administered nonpregnant rat's uterus showed strong expression for COX-2 in endometrium contacted with lumina epithelial lining of rat uterus and in myometrial mucosa. Stromal cells showed more staining than untreated nonpregnant rat's uterus and stronger staining in stromal cells contacting myometrial layer compared to untreated nonpregnant rat's uterus. SP-6 acupuncture administered nonpregnant rat's uterus showed weak expression for COX-2 in myometrial layers and stromal cells but no staining was visible in lumina epitheliai and glandular epithelial cells. Few stromal cells and myometrial mucosa were positively stained for COX-2. Pregnant SD rat's uterus was also immunostained for COX-2 expression after 18 days of pregnancy. Unlike to untreated nonpregnant rat's uterus, luminal epithelial cells were not positively stained for COX-2 but stronger staining for COX-2 was revealed in stromal cells. LI-4 acupunctured SD rat's uterus had very strong expression of COX-2 in luminal epithelial lining. Few stromal cells showed stronger positive COX-2 staining and myometrial layers also showed more expression than untreated pregnant rat. SP-6 acupuncture administered pregnant SD rat's uterus showed positive expression of COX-2 in epithelial cells of luminal mucosa layer but weaker than that of LI-4 acupuncture treatment's case. However, strong positive staining was revealed in stromal mucosa and myometrial layers. Virgin SD rat's uterus motility index during LI-4 acupuncture was 66.52 % (Prob〉T = 0.0197) compared to its motility before the acupuncture treatment but the motility index was slighdy elevated up to 79.58 % (Prob〉T = 0.1175) after the acupuncture. During the SP-6 acupuncture treatment for 30 minutes, uterus motility index was 90.52 % (Prob〉T = 0.1832) showing lesser decrement but consequently reached similar motility index decreasal to 79.95 % (Prob〉T = 0.0215) after the acupuncture treatment as LI-4 showed. LI-4 acupuncture tend to be a quick treatment to reducing the uterus motility in a virgin rat but eventually both two acupuncture administration created very similar reduction of uterus motility seeing the index after the both acupunctures. The uterus movement monitored during the LI-4 acupuncture administered for 30 minutes, Pregnant SD rat showed decreased motility down to 77.90 % (Prob〉 T = 0.0076) compared to uterus motility before the acupuncture and it continuously decreased down to 71.81 %(Prob〉T = 0.0214) after the removal of needle. The statistical analysis using paired t-test showed significance difference for both two motility indexs at =0.05. SP-6 acupuncture administered to pregnant SD rat also had similar pattern of decreasing uterus motility index down to 74.70 % (Prob〉T = 0.1730) during the initial 30 minutes acupuncture administration and it was continuously lowered to 71.52 % (Prob〉T = 0.0155) after the acupuncture. The paired t-test resuit for SP-6 suggest prompt response of uterus motility index to the SP-6 acupuncture treatment but consequently reached same level of inducing the motility reduction as LI-4 at =0.05 level.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.2
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• pp.361-374
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• 2018

The country has built and is operating IT-based integrated management system for efficient management of national highway tunnels used publicly these days. Since this system doesn't include the management function on earthquakes, it is impossible to promptly respond to earthquakes and to select the sections requiring seismic reinforcement. Tunnels designed and constructed after 1999 have been subjected to seismic design for an earthquake with a return period 1000 years. Therefore, it is necessary to evaluate the stability of structures in case of earthquakes more than this. Since it takes a lot of time to perform the stability evaluation on various earthquake magnitudes, a method that can easily evaluate earthquakes is needed. In this paper, the empirical simplification method that can easily evaluate the earthquake was proposed. For this, the study calculated ground displacement by conducting one-dimensional ground response analysis, and examined the safety of tunnels in the event of occurrence of an earthquake using two means of response displacement method (analytics and numerical analysis).

• Tunnel and Underground Space
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• v.10 no.1
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• pp.25-32
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• 2000

This paper presents two new extensions to the DDA method. The extensions consist of sequential loading or unloading and rock reinforcement by rockbolts, shotcrete or concrete lining. Examples of application of the DDA method with the new extensions are presented. Simulations of the underground excavation of the Unju Tunnel of Kyungbu High Speed Railway Project in Korea were carried out to evaluate the influence of excavation sequence and reinforcement on the tunnel stability. The results of the present study indicate that improper selection of excavation sequence could have a destabilizing effect on the tunnel stability. On the other hand, reinforcement by rockbolts and shotcrete can stabilize the tunnel. It is found that, in general, the DDA program with the three new extensions can now be used as d practical tool in the design of underground structures. In particular, phases of construction (excavation, reinforcement) can now be simulated more realistically.

• The Journal of Engineering Geology
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• v.14 no.3 s.40
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• pp.287-300
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• 2004

By using a simple conceptual model, a sensitivity analysis is performed to examine the effects of changing model parameters on the model outputs, the groundwater discharge and the radius of influence, induced by tunnel construction. The results indicate that the model outputs are most sensitive to the tunnel depth and the hydraulic conductivity, and their sensitivities vary with time. It is also revealed that the sensitivity of the specific yield in- creases constantly with time, and therefore it is as important as the hydraulic conductivity for constructing a wet-system tunnel. A transient model is suggested to simulate the stepwise tunnel excavation and the watertight lining. The model is used for a tunnel construction site to predict groundwater mow into the tunnel and the transient response of the surrounding aquifer system. The predicted results are highly sensitive to the hydraulic conductivites assigned by model calibration. Thus, a postaudit should be made to reduce the uncertainty of the predictive model.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.3
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• pp.257-267
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• 2008

Tunnels acting as drains involve groundwater-related problems such as deterioration of drainage systems or leakage through the linings. Generally initial and minor leakage problems can not be recognized by naked eyes. When the leakage over the linings is noticed, damages to structures and facilities have already occurred and could be considerable. Therefore it is vital to recognize initial leakage as early as possible and provide appropriate measures. Detection of leakage under operation requires installing piezometer. However, that may cause destruction of water proofing sheet which is generally not allowed. In this study electric resistivity method, one of the geophysical surveys, was adopted to detect possible leakage through tunnel linings. Physical lining models were made in the laboratory. The electric response was monitored for varying hydraulic conditions. It is shown that the method is very useful to detect initial leakage and monitor the malfunction of drainage system. Furthermore the method can also be used to check the quality of any repairing works of linings.

• Journal of Korean Tunnelling and Underground Space Association
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• v.3 no.4
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• pp.3-15
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• 2001

Generally, it has been noted that underground structures have a consistent record of suffering much less damage than surface facilities during earthquakes; but it is still necessary to illustrate the dynamic response of tunnel structures subject to earthquake loadings and to provide the appropriate method for the seismic analysis of underground tunnel structures since many types of underground structures have been and will be constructed in countries situated within seismic zones. In this study, first, seismic analyses for underground tunnel structures are performed by using quasistatic analysis method and dynamic analysis method. Second, seismic analyses in tunnel portals are performed by using above methods. The results of seismic analyses for the tunnel structure show that the tunnel structure conforms to ground deformation and that seismic design by using the quasi-static analysis method is more conservative than that by using the dynamic analysis. The results of the dynamic FEM analysis for the tunnel structure show that the simplified 2-D FEM analysis using a sine wave rather than the 3-D FEM analysis can be adopted for seismic analysis. Finally, the results of the dynamic FEM analysis in tunnel portals show that the force acting on the lining is largest near to the tunnel portal when an earthquake wave propagates parallel to tunnel axis.