• Tunnel and Underground Space
• /
• v.27 no.1
• /
• pp.12-25
• /
• 2017

In local underground mines heavily depending on the natural ventilation, ducted fan auxiliary ventilation system is strongly recommended instead of the total mine ventilation system requiring large capital and operating costs. Optimizing the installation of ducted fans in series in long large-opening mines is required to assure the economy and efficiency of the ventilation system. The two most critical design parameters for optimization are the wall separation distance and gap length between adjoining ducts. This study aims at deriving the optimal values for those two parameters concerning the economic and environmental aspects through the extensive CFD analysis, which minimizes pressure loss, leakage and entrainment of the contaminated air in the gap space. The ranges of the wall separation distance and gap length for study are selected by taking into consideration the existing recommendations and guidelines. The ultimate goal is to optimize the auxiliary ventilation system using ducted fans in series to provide a reliable and efficient solution to maintain clean and safe workplace environment in local long underground mines.

• Journal of Korean Society of Transportation
• /
• v.26 no.1
• /
• pp.155-164
• /
• 2008

Variable Message Signs (VMS) is one of the major components for Intelligent Transport Systems (ITS) services that provides real-time traffic and incident information to drivers. The objective of this research was to develop a method determining the optimal location of VMS considering safety and driving characteristics of various drivers. A driving simulator was utilized to evaluate how drivers can safely exit to off-ramp depending on various VMS locations while information relating route diversion was provided. The binary logistic regression and factor analysis were applied in developing a probability model that predicts the success of safe off-ramp exiting. Based on the developed probability model, a method to estimate the spacing between VMS and off-ramp is suggested. It is expected that the products of this study would be utilized as a tool in determining VMS locations for ITS planners and designers.

• Journal of Korean Society of Disaster and Security
• /
• v.11 no.2
• /
• pp.17-28
• /
• 2018

The purpose of this study is to investigate the effect of underground facilities around excavation zone on groundwater flow characteristics during excavation. The scenarios were constructed considering the size of the underground facility, the separation distance, and the hydraulic gradient. As a result, as the size of the underground facility increases, the difference of head and the hydraulic gradient become large. The shorter the separation distance of underground facility is, the more the difference of head and the hydraulic gradient occur. The effect of hydraulic gradient on model area was relatively small. As a result of analysis of groundwater flow rate for the scenario, groundwater flow rate tends to decrease as the size of underground facility increases or groundwater flow rate tends to decrease as the separation distance decreases. It is necessary to examine the effect of underground facilities on the groundwater flow analysis in the ground excavation.

• Explosives and Blasting
• /
• v.21 no.4
• /
• pp.11-21
• /
• 2003

An experimental study was carried out in order to reduce the period and cost of construction of Missiryung tunnel, which is a relatively long one 3.6 km long. An allowable vibration level for curing concrete was established based on the extensive case studies done over the world. and assessment was performed on the possibility of constructing concrete structures like lining during tunnel blasting. Attenuation relationships were obtained by processing more than 130 measurement data from a series of tunnel blasting in the site. A Guideline for safe construction work was suggested. To verification, low small concrete blocks with a constant standoff distance were installed in the floor of the tunnel After the blocks were exposed to blast vibrations for 28 days, compressive strength tests were performed on 20 specimens taken from the blocks. It was shown that the suggested guideline was appropriate for the safe construction work at the site.

• Journal of the Korean Geotechnical Society
• /
• v.19 no.5
• /
• pp.79-87
• /
• 2003

Underground flexible pipes for electric cables are subject to external loads and surrounding soil pressure. Particularly, strain of flexible pipes is of great concern in terms of safety and maintenance of electric cables. In this paper, stress and strain of flexible pipes with two types of installation gap, ie, l0cm and naught, were compared to investigate the structural integrity of pipes from actual field test. The effect of degree of compaction and burial depth were also investigated to simulate the variety of construction situation. The results of the field test show that the strain criteria were satisfied under the burial depths of 80cm, 100cm and 120cm regardless of installation gap.

• Journal of Navigation and Port Research
• /
• v.38 no.4
• /
• pp.327-333
• /
• 2014

The Convention on the international regulations for preventing collisions at sea, 1972(COLREGs) defines the collision avoidance principles and various navigation rules for the prevention of collision at sea. In particular, the initial responses to avoid risk of collision are mainly decided by navigation officer's experience and subjective judgement. However, collision accidents could be effectively prevented if the minimum criteria of quantitative initial response are suggested to the junior officers and the cadets who have insufficient sea experience and navigation competency. This study reviewed the COLREGs terms related to the initial response and the existing papers concerned with risk assessment model. A questionnaire survey is also carried out for safe passing distance, degrees of alternating course and initial response distance to avoid collision in accordance with various encounter situations. Base on these results, we propose the proper minimum safe passing distance between the vessels, the initial response distance and required turning angles for alternation in each encounter situations. The suggested criteria of initial response will contribute to the prevention of collision at sea as well as the improvement of gradual navigation technology.

• Proceedings of KOSOMES biannual meeting
• /
• 2018.06a
• /
• pp.53-53
• /
• 2018

• Proceedings of the Korean Institute of Navigation and Port Research Conference
• /
• 2011.11a
• /
• pp.21-22
• /
• 2011

In this study, an analytical algorithm for collision avoidance is proposed, which is applicable to designing collision avoidance maneuvers for two encountering ships. The minimum separation distance is defined and an appropriate maneuver sequence is computed for safe and effective collision avoidance. Two approaches: 1) collision avoidance through speed change and 2) collision avoidance through heading change, are considered, and the initiation point of the avoidance maneuver is computed analytically using the geometric configuration of the two encountering ships. To verify the feasibility of the proposed algorithm, numerical simulations are carried out using a set of ship-to-ship encountering scenarios.

• Proceedings of KOSOMES biannual meeting
• /
• 2017.11a
• /
• pp.173-173
• /
• 2017

• Explosives and Blasting
• /
• v.24 no.1
• /
• pp.39-48
• /
• 2006

The various alternatives to reduce the construction period and cost in the wide and long tunnel have been attempted recently. However, the concrete lining forming process after finishing tunnel excavation may delay construction period considering the specific conditions of the wide and long tunnel. The concrete lining is indispensible for the road tunnel. For this reason, the blasting-lining synchronizing study had been carried out to reduce construction period in the Gyea-Ryong Tunnel. Lining models were installed at four different distance conditions the floor of the tunnel. After model installation, hundreds of blasting vibration measurements and concrete material tests were performed to calculate the safe distance between blasting point and concrete lining form. The study also introduces a method which can obtain the better ability of construction by improving working environment with the ventilation and the relocation of tunnel equipments in the working places.