• Tunnel and Underground Space
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• v.10 no.1
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• pp.80-91
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• 2000

Open cut mining of limestone is generally considered to be more advantageous than underground mining in recovery, grade control, economics, and safety, but it causes substantial environmental pollutants such as ground vibration, noise, dust. It also changes ground surface and may destroy vegetation. The Halla limestone mine which lies adjacent to Baikdu mountains range is selected for a model study. To reduce environmental hazards, and to conserve original surface and woods, both open cut and underground mining methods must be adopted. In case of sub-level sloping. a unit block of 87m high, 70m wide, and 100∼l20m long is suggested with an estimated overall recovery of 42%. Some suggestions to reduce the environmental hazards are also included. The followings must be considered in determining the degree of fragmentation; the discontinuity conditions in the rock mass and the charge concentration both at the bottom and column of the hole. In addition to adopting a barrier wall for reducing environmental hazards, the probable production from underground mining is also discussed.

• Journal of Korean Society of Transportation
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• v.23 no.4 s.82
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• pp.47-55
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• 2005

In recent years, the rapid growth of vehicles have increased traffic crashes. Since they can cause the economic losses and have put the life qualify in danger, there should be numerous efforts to reduce traffic crashes. To reduce traffic crashes, this research seeks to improve the safety of intersections by analysing causations of injury severity with Ordered Probability Model. This research applied the Ordered Probit Model, which assumes that ${\epsilon}_i$(random error) is normally distributed, for model calibration and used $p^2$ (likelihood ratio) and $x^2$ (Chi-square) for model selection. The results show that minor road traffic, heavy vehicle rates, major and minor right-turn rates, presence of lightings, speed limits, instructive line for left-turn traffic are significant factors affecting crash severities at signalized intersections.

• Journal of Korean Society of Transportation
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• v.25 no.6
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• pp.33-42
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• 2007

This research proposes strategies about providing detour route information and traffic management for flood disasters. Suggested strategies are based on prevention and preparation concepts including prediction, optimization, and simulation in order to minimize damage. Specifically, this study shows the possibility that average travel speed is increased by proper signal progression during downpours or heavy snowfalls. In addition, in order to protect the drivers and vehicles from dangerous situations, this study proposes a route guidance strategy based on variational inequalities such as flooding. However, other roads can have traffic congestion by the suggested strategies. Thus, this study also shows the possibility to solve traffic congestion of other roads in networks with emergency signal modes.

• Journal of Korean Society of Transportation
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• v.34 no.6
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• pp.535-547
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• 2016

This study aims to identify factors that affect the degree of injury severity sustained in traffic crashes on work zone of Korean expressways. To this end, decision tree method was applied to identify influential factors on injury severity and compare characteristics of those factors between work zone and non-work zone. The results from the comparison show that the risk of severity was low when traffic volume and heavy vehicle ratio are high because the factors lower the overall section speed. On the other hand, when the traffic volume and the heavy vehicle ratio are low, the section speed increased and the tendency for high injury severity was confirmed. These findings are expected to help transportation planners and engineers understand which risk factors contribute more to severe injury in the work zones such that they can effectively prepare and implement safety countermeasures.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.16 no.5
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• pp.83-89
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• 2002

The purpose of this paper is to assess experimentally system stability of the 154［㎸］transmission system due to the current of the forthcoming AC High-Speed Railway (HSR) era. It introduces a simple method to evaluate the system stability. The proposed method also shows the relationship between stability and power losses, and the stability indices made by the numerical process proposed in this paper will be used to assess whether a system can be stabilized or not. This paper also presents the improvement of the stability via loss reduction using a shunt compensator. Reactive power compensation is often the most effective way to improve both power transfer capability and system stability. The suitable modeling of the traction power system should be applicable to the PSS/E. The proposed method is tested on a practical system which will be expected to accommodate the heavy HSR load.

• Journal of Navigation and Port Research
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• v.30 no.1 s.107
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• pp.29-34
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• 2006

This study aims to provide divers with improved sqfe diving practices by analyzing reports on scuba diving casualties that recently (from 1997-2003) occurred in Korea, Japan and USA The result of this study may contribute to reduce the diving accident. The data were collected through the diving accident reports of various sources, which include reports of the KUA (Korea Underwater Association) technical committee, the accident statistical data of Korea Coast Guard, articles of domestic and foreign scuba diving magazines, accident reports of various newspapers, annual reports on decompression illness and diving fatalities by DAN (Diver Alert Network), diving accident data reported to local and national seminars, and medical treatment data of diving accident. The analysis focused on the diving casualties and the result showed that the casualty rate in Korea was 2.8 and 2.2 times higher than those in Japan and USA, respectively.

• Journal of the Korean Institute of Gas
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• v.16 no.5
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• pp.21-27
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• 2012

The loss of life and property due to accidents in the research facilities or the laboratories of the university occurs steadily and the necessity of laboratory accident prevention is proposed. Above all, the main work to laboratory accident prevention is a systematic analysis of laboratories accidents. Analyzing reports or researches on industrial accidents in Korea had been carried out but these researches or reports did not based on laboratory accidents analysis. To the establishment of the accident prevention countermeasure in laboratory, a questionnaire sheet has been developed in this study. The questionnaires to survey the accident cases were gathered by electronic mail and visit survey from the laboratories and universities. The data of accident cases from the questionnaires was analyzed and discussed on accident distribution by season, the type of accident classification, the type of occurrence, the objects that caused the accident and laboratory accident by the damage incurred etc.. These results of this study can be used as basic data to the safety security and laboratory accident prevention of the laboratory worker.

• Proceedings of the Korean Geotechical Society Conference
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• 2006.10a
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• pp.56-65
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• 2006

As portions(28m) of the designed tunnel was crossing the abandoned tunnel, methods for safe construction were demanded. The level of the abandoned tunnel and the designed tunnel was almost same and each tunnel was crossing at an angle of about 40 degrees. Therefore the abandoned tunnel would adversely affect the stability of the designed tunnel. Some sections of the abandoned tunnel passes through the designed tunnel wall were fully filled with tunneling spoil and cement milk grouting to increase tunnelling stability. By checking physical properties of grouting cores drilled at the cross section of the designed tunnel and the abandoned tunnel, the quality of material filled in the abandoned tunnel was confirmed. Also the stability of the designed tunnel was checked by the monitoring during excavation of the tunnel.

• International Journal of Highway Engineering
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• v.6 no.2 s.20
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• pp.37-45
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• 2004

The asphalt concrete pavement takes various advantages of better riding quality, serviceability and easier maintenance. At the same time, it addresses a weak point of the premature failures due to rapid increasement of traffic volume, heavy vehicles and high temperature in summer. It increases the expenditure of maintenance and repair. In order to improve the performance of asphalt pavement avoiding this premature failure, the use reinforcements with geosynthetics have been considered. Geosynthetics are known as an effective reinforcement to restrain fatigue and reflective cracks in asphalt pavements. In this study, a comprehensive parametric study is conducted to capture the efficiency of geosynthetic-reinforcements using viscoelastic properties of the asphalt concrete(AC) layer. The investigated parameters were reinforcement location, AC layer thickness, temperature distribution across the AC layer and modulus of AC and base layer. As a result of observations, that reinforced asphalt concrete could be used effectively for improving resistance against fatigue cracks and permanent deformation. Especially, when a geogrid was placed at the interface between the asphaltic base and the subbase, tensile stress in the horizontal direction was significantly reduced.

• Tunnel and Underground Space
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• v.12 no.1
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• pp.31-36
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• 2002

This paper concerns smoke propagation in tunnel fires with various size of fire source. Experiments carried out in model tunnel and those results were compared with numerical results. The Froude scaling law was used to scale model tests for comparison with larger scale tests. In order to validate for numerical analysis, temperature distribution of predicted data was compared with measured data. Examining the temperature distribution, we found that smoke layer does not come down under 50% of tunnel heights for a short tunnel heights for a short tunnel firs without ventilation. Front velocity of smoke layer is proportional to the cube root of heat release rate. And it is in good agreement with existing empirical expression and numerical prediction. In a short tunnel fire, horizontal propagation of smoke layer is more important than vertical smoke movement for evacuation plan.