• Journal of the Korean Geotechnical Society
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• v.19 no.6
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• pp.273-283
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• 2003

Fissured rock and soft ground always suggest, problems in the construction of the underground space. The stress release of the weak underground material by opening the underground space with a soft ground, fissures and joints can lead to the failure of the opening. Grouting of the weak rock and the soft ground, which is a process of injecting some bonding agents into the soft ground, is one of the measures to reinforce the soft ground and to prohibit the failure of the underground construction due to the stress release. The proper installation of the grouting is essential to ensuring the safety of the tunneling operation, so that the evaluation of the grouting performance is very significant. The general procedure of evaluating the grouting is coring the grouted section and measuring the compression strength of the core. However, sometimes when the grouted section is at the crown of the tunnel and the grouting is installed at a wide section, the coring is not good enough. This study is oriented to propose a new and a non-destructive procedure of evaluating the grouting performance. The proposed method is based on the wave propagation of elastic waves, and evaluates the shear stiffness of the ground and investigates the anomalies such as voids and cracks. The SASW ( Spectral-Analysis-of-Surface-Waves) method is one of the candidate s to make the inspection of the pouting performance, and is adopted in this study. The practical grouting activity was monitored by SASW method, and the proposed method was applied to the inspection of the grouting performance to check the verification of the proposed method.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.1
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• pp.41-52
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• 2016

When the queue length of congestion vehicles in tunnel fire is extended beyond tunnel length, the capacity of smoke control system needs to be increased in line with ventilation resistance. However, the vehicle queue length is not defined, so a rational equation is necessary in current fire prevention guideline. This study is intended to propose an equation to calculate the queue length considering the number of vehicles in queue in tunnel fire and evaluate the applicability by tunnel length as well. When it comes to normal tunnel, it is necessary to compare the vehicle queue length with tunnel length up to the length of 1,200 m in a bid to avoid applying the vehicle queue length excessively in case of fire. As a result of evaluation of applicability to model a tunnel, saving the number of jet fan for smoke control appeared to be effective. Besides, quantitative approach to explain the vehicle queue length through the relationship between the percentage of large vehicles and tunnel length was presented. Consequently, when the queue length of the congestion vehicles exceeds the tunnel length in determining the capacity of smoke control system in case of fire, the number of vehicles beyond the tunnel length needs to be excluded from estimating the ventilation resistance by vehicles.

• Journal of Korean Tunnelling and Underground Space Association
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• v.10 no.2
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• pp.185-191
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• 2008

Today, Large and bigger underground construction are increased. In this study, Blating used electronic detonation (OBM Method) and non-electric detonation are carried out. Through comparison with two method, reduction of vibration and noise and efficiency of construction are investigated. As a result of this study, using electronic detonation is shown that it can control lower vibration and noise level, and better HCF, mucfile, advance rate and fragmentation.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2016.10a
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• pp.827-829
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• 2016

장시간 컴퓨터나 스마트폰을 사용하는 사람들에게서 손목터널증후군(Carpal Tunnel Syndrome)의 발생 가능성이 높아지며, 이를 방지하기 위해서는 꾸준한 손목 스트레칭과 위험성의 모니터링을 통한 사용자 피드백이 중요하다. 본 연구에서는 사용자 스스로가 손목 터널 증후군의 위험성을 인지하고, 손목 스트레칭 할 수 있도록 손목 터널 증후군 예방 시스템(Carpal Tunnel Syndrome Prevention System, CTSPS)을 구현하였다. 전체 시스템은 하드웨어와 소프트웨어로 구성되며, 소프트웨어는 사용자가 설정한 사용 시간과 잠금 시간을 바탕으로 알림 및 잠금을 수행한다. 이때 사용자는 아두이노와 가속도 센서를 이용하여 손목 스트레칭 할 수 있으며, 사용 패턴을 분석하여 사용자에게 맞는 생활 가이드를 제공할 수 있다. 구현된 시스템을 평가하기 위해 피실험자 5명을 대상으로 3일간 스마트폰 사용 시간 및 터치 횟수를 측정하였고, 설문조사를 수행한 결과 스마트폰의 사용 빈도가 줄었으며, 통증 완화 등 긍정적인 효과를 확인할 수 있었다.

• Proceedings of the Korean Geotechical Society Conference
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• 2004.03b
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• pp.433-441
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• 2004

국내 발파 현장에서 사용되고 있는 폭약류에 강력한 폭굉력을 충분하게 발휘하기 위해서는 뇌관(Blasting cap, Detonator)의 역할이 중요하다. 그리고 이 뇌관의 정밀성에 따라 발파 효율의 차이가 있게된다. 초기의 도화선 및 공업뇌관에서 시작하여 현재 정밀성 면에서는 MS(Milli Second)뇌관의 경우 20ms또는 25ms의 정밀한 시차로 순차적으로 기폭함으로써 발파효과의 극대화와 소음 및 진동제어에 큰 효과를 이루었으나, 최근 개발된 진자뇌관의 경우 자체 IC회로를 내징하여 $1{\sim}2ms$의 초정밀시차(오차범위 $0.1{\sim}0.2ms$이내)의 구현이 가능해짐에 따라 이를 적절히 조합하여 설계함으로써 각종 제어발파, 파쇄도 향상, 암손상영역 저감 등의 효과에 대해 국외에서 연구가 진행되고 있는 것으로 알려지고 있다. 그러나 우리나라와 같이 도심지 발파 및 터널이나 노천 현장 근거리에 보안물건이 위치해 있어 진동제어가 절실히 필요한 상황에서 진동제어에 효과가 있는 것으로 알려진 전자뇌관에 대한 연구가 이루어지고 있지 않은 상황에서 본 연구는 앞으로 이루어질 전사뇌관에 대한 수많은 연구에 기초자료를 제공하고자 실시하였다. 본 연구에서는 이를 위해 국내에서 최초로 2003년 9월 23일 강원도 양구 지역읜 00터널에 전자뇌관을 이용한 시험발파를 실시하였고, 발파에 의한 진동 등을 조사하여 그 효율성을 검토하였다. 이를 위해 전자뇌관의 특성과 장점을 최대한 살리기 위하여 각공을 발파하는 방식, 즉 1지발에 1공을 발파하는 방식을 채택하고 비전기 뇌관과 전자뇌관으로 설계를 하여 각각의 발파효율을 비교하여 보았다. 그 결과 발파신동의 경우 비전기뇌관을 이용하여 1공씩을 1지발로 발파를 한 경우에는 18${\sim}$56%의 진동저감 효과가 있었고, 번 설계에 의해 진해오딘 발파에 비하여는 최대 70% 이상의 진동저감 효과가 있는 것으로 나타났다.

• Explosives and Blasting
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• v.42 no.1
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• pp.1-11
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• 2024

Through existing research and construction cases during tunnel blasting, the electronic blasting method is reported to be more effective in reducing blast vibration than the normal blasting method. However, due to the high price of electronic detonators, they are only used in some blasting sites where security objects are located nearby. Accordingly, this study performed tunnel blasting tests by adjusting the ratio of electronic and non-electronic detonators. And through the research results, the reduction effect of blasting vibration according to the detonator ratio was evaluated. The research results showed that the reduction effect of blast vibration was greatest when 100% electronic detonator was applied. In addition, when more than 52% of the electronic detonator was applied, it was found that the reduction effect was similar to the reduction effect when 100% of the detonator was used.

• The Journal of Engineering Geology
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• v.20 no.2
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• pp.147-153
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• 2010

Cut-off wall with a low permeability can be constructed to prevent groundwater seepage in spillway tunnel areas. Three spillway tunnels are constructed in Im-ha multipurpose dam region and three types of cut-off walls with a variety of directions and scales are designed. As a result of MODFLOW modeling to assess the effect of cut-off wall for three types, groundwater inflows to the tunnels range from 64.26 $m^3/day$ to 65.49 $m^3/day$ and also they through a cut-off wall section from a reservoir do from 44.08 $m^3/day$ to 45.31 $m^3/day$ and it does not show any significant difference among them. Therefore, a construction process and an environmental conservation rather than the effectiveness of cut-off wall need to be considered to select the best cut-off wall in this region.

• Journal of the Korean Institute of Gas
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• v.15 no.3
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• pp.31-38
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• 2011

In this study, we investigate simulation studies to confirm the removal of smoke through ventilation when the subway car is on fire and stopped in an underground subway tunnel, by using Fire Dynamics Simulator (FDS) which is being upgraded by NIST. The structure of subway tunnel and train for simulation modeling are based actual data from Seoul metropolitan subway. The main purpose of this study is to assure the removal efficiency of the ventilation when changing the ventilation capacity between 2.0 m/s and 3.0 m/s. The results of the study shows that carbon monoxide (CO) and carbon dioxide ($CO_2$) are reduced by about 35% as the ventilation capacity is increased by 0.5 m/s. This study also performs the grid sensitivity verification of FDS for improved accuracy of the results. To find the effective size of the grid, three cases are simulated and the results are compared.

• Journal of the Korean Geotechnical Society
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• v.33 no.8
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• pp.17-27
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• 2017

Gangwon province which is located in northeast of Korea is the coldest region where average daily temperature is below zero during winter while the other regions are above zero. However, there have been insufficient researches on the insulation design and the effect of the insulation on the freezing damages, even though freezing damages were reported consistently in the lining of road tunnel during winter. In this study, to investigate the effect of insulations on the reduction of freezing damages, numerical analysis was performed considering geotechnical and meteorological characteristics in Gangwon province during winter. As a result, it was found that thickness of concrete and shotcrete in lining had negligible effect on the freezing depth while the insulation had significant effect on it. In addition, because the freezing depth is greatly affected by the thermal conductivity of the ground behind the lining in the period of cold weather, these effects should be considered in the estimation of the insulation thickness.

• Journal of the Korean Society for Railway
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• v.18 no.6
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• pp.567-577
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• 2015

This paper presents an assessment method of the ground vibration level with a combination of measured data and an analytic method. The basic concept of the method is similar to that in FRA(Federal Railway Administration) manual for detailed vibration analyses. However, going into detail, the assessment method was modified for a feasible evaluation of the vibration reduction effects of diverse types of wave barriers. The force density was evaluated in a vehicle-track interaction analysis and the transfer mobility of vibration was analyzed through a 2-D ground vibration analysis. The calculated 2-D transfer mobility was corrected to incorporate transfer characteristics of actual ground vibration by comparing the previously measured data and analysis results. Nine types of vibration reduction effects of wave barriers were analyzed on a shallow tunnel section of an urban railway where numerous civil complaints had actually been filed.