• Tunnel and Underground Space
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• v.23 no.6
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• pp.521-537
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• 2013

While microseismicity induced by hydraulic stimulation carried out for EGS is useful means in estimating the range of permeability increase, it also affect surface structures and environments. In order to establish a mitigation plan for microseismicity triggered by hydraulic stimulation, we reviewed world-wide guidelines on the impact of ground vibration on the surface structure and human environment by blasting. Case studies from Europe and USA on the microseismicity by hydraulic stimulation are presented and suggestions are made for the guidelines on ground vibration by hydraulic stimulation for the ongoing Pohang EGS project.

• Tunnel and Underground Space
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• v.15 no.5 s.58
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• pp.369-377
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• 2005

The stability of underground openings is a major concern for the safety and productivity of mining operations. Rock mass classification methods provide the basis of many empirical design methods as well as a basis for numerical analysis. Of the many factors which influence the stability of openings, the span of the opening for a given rock mass condition provides an important parameter of design. In this paper, the critical span curves proposed by Lang, the Mathews stability graph method and the modified critical span curve suggested by the authors have been assessed. The modified critical span curve was proposed by using Mathews stability graph method. The modified critical span curve by the author have been used to assess the stability of underground openings in several limestone mines.

• Journal of the Korea institute for structural maintenance and inspection
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• v.18 no.3
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• pp.69-75
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• 2014

The priority of repair areas are chosen with the probability distribution of 0.3mm wide crack and carbonation induced corrosion. Data is analyzed and evaluated based on the 28 section of Precise Inspection for Safety and Diagnosis (PISD) in seoul. As the crack is distributed in log-normal, the carbonation and cover are in normal distribution. To have rational in repair sections among 503 sheets of underground structure, it is adopted the reliability index as well as the environment factors: strength, sonic speed, $CO_2$ concentration, corrosion, and content of chloride.

• Journal of the Korean Society for Railway
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• v.12 no.3
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• pp.329-334
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• 2009

Subway is used as a useful transportation method to solve the metropolitan traffic problem for its advantages of being not only accurate, safe and massive, but also of not producing any exhaustion gas in compare with the other ground transportation systems. However, noise inside the car due to concrete based rail track and tunnel structure has become a social problem. So, an analysis on the noise characteristics according to their routes and locations was made on the basis of the actually measured results from the trial run. To reduce the interior noise of subway train, the side part of rolling stock should have a noise blocking system fur low band frequency noise, the floor of it should have that for medium range frequency noise and the side part as well as lower part of it should have good noise reduction and absorption function.

• Journal of the Korean Society for Railway
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• v.14 no.1
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• pp.39-48
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• 2011

The paper describes four practical cases of railway structure concerning a three-dimensional numerical approach to analyse dynamic soil-structure interaction(SSI)of railway tracks on layered soil under transient load in the time domain. The SSI-Model has been implemented in TDAPIII accounting for nonlinear properties of the track and soil. The approach can be also be used to calculate vibration propagation in the soil and its effect on nearby buildings and structure. The Method is applied to analyse the dynamic response of railway tracks due to a moving wheel set. Finally some sample are given in order to reduce the vibration at the point of emission, at the transmission path and the structure itself.

• Journal of the Institute of Electronics Engineers of Korea TC
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• v.42 no.10 s.340
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• pp.31-38
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• 2005

Ipsec is a security protocol suite that provides encryption and authentication services for IP messages at the network layer of the internet. Internet Key Exchange (IKE) is a protocol that is used to negotiate and provide authenticated keying materials in a protected manner for Security Associations (SAs). In this paper, we propose a dynamic key lifetime change algorithm for performance enhancement of virtual private networks using IPSec. The proposed algorithm changes the key lifetime according to the number of secure tunnels. The proposed algorithm is implemented with Linux 2.4.18 and FreeS/WAN 1.99. The system employing our proposed algorithm performs better than the original version in terms of network performance and security.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.19 no.2
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• pp.183-188
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• 2001

Topographic map is important for the additional detailed construction planning followed by slope sliding. It is a base map that is used to compute the volume of soil, the cost of construction, and check the stability in the area of slope sliding. In this study, 3D topographic data were acquired appling softcopy photogrammetry to the dangerous slope, and the method which can transform these data to the same coordinates system as early TM coordinates was designed. There was a problem when the one meter contour line was made by analysing the image taken from the distance three hundred meters. By solving this problem, this could be used as important data for the planning of road expansion construction. It is expected to be useful for the measurement of various dangerous area in civil engineering works.

• Journal of the Society of Disaster Information
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• v.9 no.1
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• pp.105-112
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• 2013

Socially, citizens' safety needs get higher, therefore support system of emergency vehicles is desperate as it is one of national services. For emergency vehicles, rapid departure and prompt field arrival are necessary. However, delay of departure occurs frequently due to traffic jam within a city so it makes citizens suffer from inappropriate service. Thus this study researched overseas examples in order to adduce solution of obstacles we have when passing through bridges and tunnel. In order to help emergency vehicles to move smoothly, a proposal of design and method for rapid support system was made.

• The Journal of Korea Institute of Information, Electronics, and Communication Technology
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• v.1 no.2
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• pp.107-122
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• 2008

Communication is be classified into public network and private network. VPN is made by integrating the circuit cost reduction of public network and the reliable security support of public network. This paper analyzes the IPSec using three layer tunneling, MPLS(Multi Protocol Label Switching) integrating 2 layer switching and 3 layer routing techniques and dedicated line from the viewpoint of security. In conclusion, VPN is better than dedicated network line in cost and security. If IPSec VPN is compared with MPLS VPN, MPLS VPN is more excellent than IPSec VPN in safe data transmission, cost, QoS and management.

• Tunnel and Underground Space
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• v.30 no.1
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• pp.1-14
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• 2020

Microseismic monitoring is utilized for the performance verification and safety management of the structure by detecting fine levels of damage. In order to construct a highly reliable microseismic monitoring system, the role of signal conditioner is critical. The signal conditioner helps with accurate data collection and precision control of the device, and performs additional functions such as signal conversion, linearization, and amplification. In this technical report, noise reduction signal conditioner suitable for mining sites was developed and reviewed for the purpose of implementing more precise monitoring by supplementing the previously developed microseismic monitoring system.