• Journal of Korean Tunnelling and Underground Space Association
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• v.21 no.6
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• pp.887-895
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• 2019

Recently, the number of underground road development projects has been increasing to solve traffic problems in the national capital region and metropolitan areas with intensified overcrowding, and there has been a tendency to plan underground roads by applying a double-deck tunnel technology that has advantages in constructability and economical efficiency. The double-deck tunnel has a structure where one excavation section is divided into two parts and used as up and down lines, and is mainly used as a road for small vehicles only due to its low floor height. In addition, due to the small cross-sectional area, it has characteristics different from those of general road tunnels in terms of ventilation and disaster prevention. In this regard, this study proposed an operational plan that applies an oversized exhaust system, which is one of semi-transverse ventilation systems, to small cross-sectional tunnels like double-deck tunnel with low floor height, and a comparative analysis between smoke exhaust characteristics according to the fire occurrence locations and oversized exhaust systems was conducted using the Fire Dynamics Simulator (FDS). The results showed that unlike uniform exhaust, intensive smoke exhaust using the oversized exhaust port maximized the delay effect of smoke diffusion and limited the smoke within 50 m above and below the fire point.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.1
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• pp.39-53
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• 2018

Generally, the total ventilation resistance coefficient in a tunnel consists of inlet/outlet loss coefficient, wall friction coefficient, and other loss coefficient caused by sudden expansion and contraction of cross-section, etc. For the tunnel before opening, when the running ventilation fan is stopped, the wind speed in the tunnel is reduced by the total ventilation resistance drag. The velocity decay method is comparatively stable and easy to estimate the wall friction coefficient in the pre-opening tunnel. However, the existing study reported that when the converging wind speed is a negative value after the ventilation fan stops, it is difficult to estimate the wall friction coefficient according to the velocity decay method. On the other hand, for the operating tunnel in which the piston effect acts, a more complex process is performed; however, a reasonable wall friction coefficient can be estimated. This paper aims at suggesting a method to minimize the measurement variables of the piston effect and reviewing a method that can be applied to the operating tunnel. Also, in this study, a new method has been developed, which enables to calculate an variation of the piston effect if the piston effect is constant with a sudden change of external natural wind occurring while the wind speed in the tunnel decreases after the ventilation fan stops, and a programming logic has been also developed, which enables dynamic simulation analysis in order to estimate the wall friction coefficient in a tunnel.

• Journal of Korean Tunnelling and Underground Space Association
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• v.20 no.1
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• pp.131-144
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• 2018

The urban center of a large city has a high concentration ratio of population, commerce, and traffic. Therefore, the expected effect is high from the introduction of the urban utility tunnel and it also has sufficient economic feasibility considering life cycle cost. Moreover, the construction cost can be greatly reduced if it is included in a large underground development such as a subway or a complex transfer center construction. However, it is not reflected in actual underground development plan. When planning a urban utility tunnel in Korea, it is expected to have difficulties such as the cost of relocation of the existing Life-Line, conflicts among the individual facility institutions, procurement of construction resources and sharing. Furthermore, it is possible to promote the project only if a consensus is drawn up by a collective council composed of all facilities and project developers. Therefore, an optimal alternative should be proposed using economic analysis and feasibility assessment system. In this study, the analytic hierarchy process (AHP) is performed considering the characteristics of urban areas and the importance of each indicator is quantified. As a result, we can support reasonable design capacity optimization using the feasibility assessment system.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.31 no.1D
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• pp.141-148
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• 2011

City of Incheon opened rapid transit(urban railroad line 1) in 1999 in order to relieve traffic congestion on major arterials. This research analyzed urban space changes of each station influenced area by examining the changes of residents, industrial employees, and floor area ratios before and after the open of Incheon urban railroad line 1. Analysis of variance was applied to change of station influence area. This research found out that the types of central business and agricultural station influence area had been changed significantly after the open of urban railroad. However, the residential, semi-residential, and suburban type of station influence area had not been changed after the open of urban railroad. Thus, it is necessary to provide diverse facilities for inducing residents and employees to the station influence area of residential and semi-residential. Furthermore, the suburban type of station influence area which is difficult to develop naturally by the law of Green Belt is needed to develop station influence area simultaneously with the construction of a station building.

• Journal of Korean Tunnelling and Underground Space Association
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• v.18 no.5
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• pp.419-429
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• 2016

In a bid to avoid the economic loss resulting from traffic jam in urban area, a deep underground road at 40 m depth has been considered and the first class disaster prevention facilities shall be applied according to domestic guideline. Automatic-monitoring fire extinguishing system designed to use for fire fighting has been widely applied at home and abroad. Recently development and commercialization through theoretical and experimental research to apply to road/railroad sector have been underway. Based on such performance of automatic fire extinguishing system, technical/economic analysis of existing water spray systems was conducted and as a result, it has demonstrated the superiority in terms of fire suppression as well as in cost efficiency. Then to commercialize this system, more diverse studies that will incorporate the characteristics of domestic tunnels are needed and should the system be promoted through institutional improvement, it's expected to become one of the advanced nations with own original technology in a life safety system industry throughout the world.

• Journal of Korean Tunnelling and Underground Space Association
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• v.22 no.4
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• pp.451-468
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• 2020

Aging tunnels with small cross-sections can cause chronic traffic jams. This problem can be solved by widening the tunnel. In general, when the tunnel is expanded, the outer portion of the existing tunnel is excavated through a mechanical or blasting method. Such excavation affects not only the surrounding ground but also the existing tunnel. The application of the pre-cutting method can be a solution to these problems effectively. Therefore, if the widening of tunnel is performed by applying pre-cutting method, analysis of the impact of this method must be performed. In this study, in order to analyze the effect of applying pre-cutting in tunnel widening, numerical analysis is performed at six ground grades, from grade I to weathered rock. The analysis is performed with the expanding lane and the excavation length of pre-cutting as variables. In addition, the analysis is focused on the displacement of crown of the existing tunnel and the enlarged tunnel. As a result, the crown displacement of the enlarged tunnel is confirmed to converge at the same value regardless of the excavation length of the pre-cutting when the tunnel widening is completed. In the case of existing tunnels, uplift of crown occurs within 5 m of the front of the tunnel surface, and the shorter the excavation length of pre-cutting is found to be effective in preventing the occurrence of uplift.

• The Journal of The Korea Institute of Intelligent Transport Systems
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• v.12 no.5
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• pp.13-21
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• 2013

Super high-rise buildings of combined use such as large shopping malls and multiplex etc. have larger parking facilities than general buildings and are characteristic of an increase in the number of the entrance and the exit connecting internal external space of the parking lot. These features cause a congestion of internal traffic by increasing car driving distance in the parking lot, and vehicle idling increases by drivers wander the parking lot in order to find parking space. In addition, they make drivers suffer from lots of difficulties due to parking including increasing their walking line after parking. Therefore, in this study, we developed individual parking information provision algorithm to specify the optimal parking place for drivers according to the purpose of visiting a building and the drivers' moving path, and selected new construction site for the second lotte world in order to evaluate the algorithm developed and performed evaluation. As a result of the evaluation, it was analyzed that in the case of applying the individual parking information provision algorithm compared to the existing parking information provision algorithm, moving distance in the parking lot decreases around 7.43~83.4%, and that in the case of $CO_2$ emission, it decreased about 47.7% on average, which indicates that the efficiency resulted from application of the individual parking information provision algorithm is very high as the application effects are tested.

• Journal of the Economic Geographical Society of Korea
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• v.18 no.4
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• pp.539-555
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• 2015

This study proposes the methodology for measuring the time-distance accessibility on the Seoul bus system based on the T-card transaction databases and analyzes the results. T-card transaction databases contain the time/space information of each passenger's locations and times of the departure, transfers, and destination. We introduce the bus network graph and develop the algorithms for time-distance accessibility measurement. We account the average speed based on each passenger's get-in and getoff information in the T-card data as well as the average transfer time from the trip chain transactions. Employing the modified Floyd APSP algorithm, the shortest time distance between each pair of bus stops has been accounted. The graph-theoretic nodal accessibility has been given by the sum of the inverse time distance to all other nodes on the network. The results and spatial patterns are analyzed. This study is the first attempt to measure the time-distance accessibility for such a large transport network as the Seoul bus system consists of 34,934 bus stops on the 600 bus routes, and each bus route can have different properties in terms of speed limit, number of lanes, and traffic signal systems, and thus has great significance in the accessibility measurement studies.

• The Korean Journal of Air & Space Law and Policy
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• v.1
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• pp.125-146
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• 1989

This paper is examine the problems of U.S.-Korea Air Service Agreement and recommend some directions for its improvement under the rapidly changing circumstance and growing importance of Korean penisula. Since the provisional agreement of 1949, U.S. -Korea Air Service Agreement has consistently been favorable to U.S. side. Fair and equal opportunity is the principle and basis of the bilateral air agreement. Notwithstanding such principle, it is only the U.S. carriers who can freely enter into any market, under the discretion of business strategy, while Korean carrier can serve only three points including Honolulu. In an effort to recitify such serious imbalance, Korea continuousely requested additional rights and has given utmost efforts to accommodate requests made by U.S. carries without much success. When we review aviation market between Korea and U.S. under the present agreement, Korea is fully open to U.S. carries as they can connect from any or all points in the U.S. via any or all points in Korea and all points beyond Korea. Increased number of U.S. carriers are enjoying greater utilization of the opportunity accorded them. Four(4) U.S. carries now operate to Korea using thirteen(13) gateway points and about one hundred fifty(150) on-line points in the U.S. such imbalance can be well understood when we review the exchange of traffic rights between the U.S. and the Pacific rim countries. During the yeras following the 1978 agreement with Korea, the U.S. proceeded to sign liberal agreements with Thailand, Taiwan, Singapore and the Phillipines. In exchange, the U.S. granted the four Pacific rim countries substantially greater rights than were granted to Korea, although Korea was the first Asian nation to sign a pro-competitive aviation agreement which granted U.S. carriers unrestricted market access and pricing flexibility. Moreover, Korea ranks the 2nd trading and tourist partner to the U.S. among the Pacific rim countries (Japan is the largest partner to the U.S. in terms of both trade and tourist market). In this paper such problems in the Korea-U.S. Air Services Agreement are analyzed in terms of historical perspective, U.S. Aviation policy, imbalance status in detail cases, discrimination to Korea comparing to other Asian countries, and theoretical application. And further it discusses current aviation issues between Korea and U.S. such as the ratification of 1980 MOU and various doing business issues of U.S. carriers in Korea. Finally, this paper concludes the analysis and suggests some directions to improve and rectify the problems and imbalance of U.S.-Korea Air Services Agreement in question.

• The Korean Journal of Air & Space Law and Policy
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• v.26 no.2
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• pp.101-124
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• 2011

Since 1961, Aviation Act has regulated all aspects related to air transport business, aviation safety and airport. However, we are to face the new challenges that have to support air transport business more efficiently and air transportation services to the people effectively in condition of the globally competitive air transport industry. In this sense, the government proposed to devide "Aviation Act" into 'Air Transport Business Act', 'Aviation Safety Act', 'Airport Facility Act' in a timely manner. At first I am to take a look about the laws of traffic-related legislation and national laws of Japanese aviation system, and to evaluate implications. In addition, the background, the organization and the main information of the Act (Draft) will be introduced. And I would like to discuss the issues raised and suggest an alternative. In particular, the name of the Act (Draft), the specifying of airport manager operater, accounting method of airport development projects belong to the nation, the delegation of the authority and other issues are discussed to provide a starting point. In conclusion, the division of current "Aviation Act" is considered absolutely necessary. To stimulate fair competition, safety regulations and efficiency, the legislation process would be desirable in the direction of the total development of the aviation industry as well as ensuring aviation safety.