• Tunnel and Underground Space
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• v.7 no.3
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• pp.208-220
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• 1997

To asses the stability of structure around shaft during the excavation of -300 ml hopper room at 2nd shaft in Jangsung mine, some measurements were made with blast monitoring, stressmeter, extensometer and inclinometers. Instrumentations proved to be reliable and data were montiored over six month period. Stressmeters were set at the points of wall and arch of inset gang(level). Induced stresses were measured with the magnitude of 2.81 kgf/$\textrm{cm}^2$(tensile stress) and -4.45kgf/$\textrm{cm}^2$(compressive stress) respectively. These values were converged after two months. The magnitude of axial force in rock bolt was measured with 1.98 ton between the points of M2(2.25m) and M3(1.5 m) but this value was assumed within allowable level. Maximum displacement was also measured with 2 mm at the dephs of 12m from surface. But this value belongs within guide level.

• Proceedings of the KIPE Conference
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• 2004.07b
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• pp.728-732
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• 2004

기존의 지하 공동구 감시 시스템은 광케이블, 누설 동축케이블(LCX), 각종 제어케이블을 사용하여 통신 선로를 구축하기 때문에 시설비가 대단히 고가이며, 여러 가지 통신선로의 이용에 따른 유지보수가 어렵고 시공기간이 길어 시설 확대에 어려움이 있었다. 따라서 통신케이블의 설치 없이 기존에 설치된 공동구의 전등용 저압 전력선을 통신선로로 그대로 이용할 수 있는 전력선 통신 기술을 적용하여 유지보수가 용이한 저비용의 지하 공동구 감시제어시스템을 개발하는 것이 바람직하다. 본 논문에서는 공동구에서의 전력선 통신의 특성을 조사, 시험시스템 설계${\cdot}$제작, 현장실증시험을 통한 성능시험 및 분석을 수행하여 전력선 통신을 적용한 안정적인 공동구 감시제어 시스템을 제안하고자 한다.

• Tunnel and Underground Space
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• v.6 no.4
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• pp.287-297
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• 1996

Input data play an important role in numerical analyses. However, it is difficult to obtain appropriate data for many reasons. In order to overcome those difficulties, an automatic MPBX(Multi-Position Borehole Extensometer) monitoring system is developed. This system can be applied to the analyses of measured data which include evaluation of the stabiliyt, efficiency of construction and the validity of numerical analyses. At first, the MPBX among field measurement tools is considered in this study. Also, 3-dimension finite element analyses are carried out to verify the influence of geological conditions and excavation sequence on the MPBX displacement. The effect of geological conditons on the displacement can be estimated qualitatively qualitavely from the measured data by plotting displacement vs. depth.

• Geomechanics and Engineering
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• v.15 no.3
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• pp.899-910
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• 2018

Terrace deposits are often encountered in portal areas and tunnels with low overburden. They are challenging to excavate considering their great mechanical and spatial heterogeneity and a very high stiffness contrast within the ground. Terrace deposits are difficult to characterize, considering that samples for laboratory testing are almost unfeasible to obtain, and laboratory tests may not be representative due to scale effects. This paper presents the approach taken for their characterization during the design stage and their posterior validation performed during construction. Lessons learned from several tunnels excavated on terrace deposits on the Bogota-Villavicencio road (central-east Colombia), suggest that based on numerical simulations, laboratory testing and tunnel system behaviour monitoring, an observational approach allows engineers to optimize the excavation and support methods for the encountered ground conditions, resulting in a more economic and safe construction.

• Tunnel and Underground Space
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• v.5 no.2
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• pp.89-94
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• 1995

Regression analysis and a comparative study were carried out for 52 blast vibration data which were monitored by changing the monitoring distance and charge per delay. The results are as follows: 1) The square and cube root scalings and general equation which have a confidence level at the point of 90% and 99% are V90=33300(SD)-2.026 , V90=23600(SD)-1.993, V90=26300W0.755 R-2.007 and V99=48400(SD)-2.026, V99=34000(SD)-1.993 , V99=38100W0.755R-2.007, respectively. 2) There is need to decide the allowable max. charge weight per delay considering the cross points comparatively of the nomogram constructed using several predictived equations. 3) It is necessary to derive the predictive equation on the basis of blast vibration level monitored in field and to decide safe vibration level and the confidence level.

• Proceedings of the Korean Geotechical Society Conference
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• 2009.09a
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• pp.700-709
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• 2009

FBG sensor system is applied to the concrete lining structure in Taegu subway. Near the structure, the power cable tunnel construction started. We wanted to measure the deformation of the structure due to the construction by the FBG sensor. The applied sensor has the gauge length of 1 meter to overcome the inhomogeneity of the concrete material with enough length. In order to fix tightly to the structure, the partially stripped parts of the sensor glued to the package and slip phenomenon between fiber and acrylate jacket was prevented. Prestrain of the sensor was imposed by controlling the two fixed points with bolts and nuts in order to measure compressive strain as well as tensile strain. The behavior of subway lining structure could be monitored very well.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2017.11a
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• pp.143-144
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• 2017

본 논문은 복선터널 라이닝의 최적 계측 측점수를 산정하기 위해 복선터널 라이닝에 작용하는 하중 조건을 대칭 분포하중이 작용하는 경우로 가정하여 터널해석 시 널리 사용되는 상용 프로그램에 하중 조건을 입력시켜 터널 라이닝의 단면 위치별 변위와 응력을 산출하였다. 산출된 변위를 계측 측점 3점, 5점, 7점으로 복선터널 라이닝 역해석 프로그램에 입력시켜서 구한 응력과 변위를 비교하여 복선터널 라이닝의 최적 계측 측점수를 산정한 결과 정확도는 측점 3점이 낮고, 측점 5점과 7점이 높으며, 현장 적용성은 측점 5점이 높은 것으로 해석되어 터널 계측 실무와 일치하는 것으로 나타났다.

• Journal of Powder Materials
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• v.26 no.1
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• pp.28-33
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• 2019

The gas sensor is essential to monitoring dangerous gases in our environment. Metal oxide (MO) gas sensors are primarily utilized for flammable, toxic and organic gases and $O_3$ because of their high sensitivity, high response and high stability. Tungsten oxides ($WO_3$) have versatile applications, particularly for gas sensor applications because of the wide bandgap and stability of $WO_3$. Nanosize $WO_3$ are synthesized using the hydrothermal method. As-prepared $WO_3$ nanopowders are in the form of nanorods and nanorulers. The crystal structure is hexagonal tungsten bronze ($MxWO_3$, x =< 0.33), characterized as a tunnel structure that accommodates alkali ions and the phase stabilizer. A gas detection test reveals that $WO_3$ can detect acetone, butanol, ethanol, and gasoline. This is the first study to report this capability of $WO_3$.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2023.11a
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• pp.247-248
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• 2023

본 논문은 단선터널 라이닝에 대칭 분포하중 작용 시 최적 계측 측점수를 산정하기 위해 단선터널 라이닝에 작용하는 하중조건을 대칭 분포하중이 작용하는 경우로 가정하여 터널해석 시 널리 사용되는 상용 프로그램에 하중조건을 입력시켜 터널 라이닝의 단면 위치별 변위와 응력을 산출하였다. 산출된 변위를 계측 측점 3점, 5점, 7점으로 단선터널 라이닝 역해석 프로그램에 입력시켜서 구한 응력과 변위를 비교하여 단선터널 라이닝의 최적 계측 측점수를 산정한 결과 정확도는 측점 3점이 낮고, 측점 5점과 7점이 높으며, 현장 적용성은 측점 5점이 높은 것으로 해석되어 터널 계측 실무와 일치하는 것으로 나타났다.

• Proceedings of the Korean Society of Disaster Information Conference
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• 2023.11a
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• pp.249-250
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• 2023

본 논문은 단선터널 라이닝에 비대칭 분포하중 작용 시 최적 계측 측점수를 산정하기 위해 단선터널 라이닝에 작용하는 하중조건을 비대칭 분포하중이 작용하는 경우로 가정하여 터널해석 시 널리 사용되는 상용 프로그램에 하중조건을 입력시켜 터널 라이닝의 단면 위치별 변위와 응력을 산출하였다. 산출된 변위를 계측 측점 3점, 5점, 7점으로 단선터널 라이닝 역해석 프로그램에 입력시켜서 구한 응력과 변위를 비교하여 단선터널 라이닝의 최적 계측 측점수를 산정한 결과 정확도는 측점 3점이 낮고, 측점 5점과 7점이 높으며, 현장 적용성은 측점 5점이 높은 것으로 해석되어 터널 계측 실무와 일치하는 것으로 나타났다.