• Journal of the Economic Geographical Society of Korea
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• v.21 no.4
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• pp.335-349
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• 2018

This study analyzes the effect of the changes in traffic environments such as transportation speeds on the time-distance accessibility for the public transportation passengers. To do this, we use passenger transaction databases of the Seoul metropolitan public transportation system: one week for each of the three years (2011, 2013, and 2015). These big data contain the information about time and space on the traffic trajectories of every passenger. In this study, the time-distances of links between subway stations and bus stops of the public transportation system at each time are calculated based on the actual travel time extracted from the traffic-card transaction database. The changes in the time-distance accessibility of the integrated transportation network from the experimental results can be summarized in two aspects. First, the accessibility tends to decline as the year goes by. This is because the transportation network becomes more complicated and then the average moving speed of the vehicles is lowered. Second, the accessibility tends to increase on the weekend in the analysis of accessibility changes by day. This tendency is because the bus speeds on bus routes on the weekend are faster than other days. In order to analyze the accessibility changes, we illustrate graphs of the vehicle speeds and the numbers of passengers by year and day.

• Progress in Superconductivity and Cryogenics
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• v.5 no.1
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• pp.103-106
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• 2003

The short circuit current problem is one of the operational problems that need to be solved by power system engineers in Korea. It is an important issue in the Seoul metropolitan area especially because of highly meshed configuration. Currently, it is regulated by changing 154 kV system configuration from loop connection to radial system, by splitting of the bus where load balance can be achieved, and by upgrading circuit breaker rating. A development project for 154 kV/2 KA SFCL application to 154 kV transmission system after 2010 is proceeding. In this paper, a feasibility study of superconducting fault current limiter (SFCL) is carried out in Seoul metropolitan area to find out the effects of its application and feasibility. This study shows that it can reduce fault current considerably, and as it can minimize the upgrading of circuit breaker rating, the economic potential of SFCL is evaluated positively.

• The Transactions of The Korean Institute of Electrical Engineers
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• v.59 no.12
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• pp.2131-2134
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• 2010

In this paper, the on-line system schemes for coordinated control system of multiple FACTS were presented to enhance the voltage stability around the metropolitan areas. In order to coordinated control system of FACTS devices, MFC on-line system calculates the optimal set point(Vref, Qrev) of FACTS devices using the coordinated control algorithm with real time network data which is transferred from SCADA/EMS system. If the system is unstable after contingencies, the new operation set-point of FACTS would be determined using bus sensitivity from tangent vector at voltage instability point. Otherwise, we would determine the new operation set-point of FACTS for considering economical operation, like as active power loss minimization using Optimal Power Flow algorithm. As the test, MFC(Multiple FACTS Coordinated control) on-line system will be installed in Korea power system.

• Journal of the Korean Society of Industry Convergence
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• v.11 no.3
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• pp.113-120
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• 2008

Rapid urbanization occurred a variety of transportation problems. Parking problem is one of the most problems of transportation problem then transportation engineers would get involved in trying to solve parking problem. A way to overcome a variety of parking problems needs preliminary data for conditions of parking but it lacks the preliminary data to do so. Thus this study analyzed a characteristic of a parking through a field survey for parking in Daegu Metropolitan City and Ulsan Metropolitan City. This study analyzed parking turnover, parking use ratio and parking basic unit for characteristic of a parking of each use districts and each cities. This study result reveals difference between the use districts' parking characteristic and cities' parking characteristic. Thus a close examination for use districts' parking characteristic and cities' parking characteristic is a prerequisite for a rational parking policy.

• Proceedings of the KSR Conference
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• 2004.06a
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• pp.842-846
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• 2004

Both traffic congestion and air pollution in the metropolitan area can be greatly relieved by promoting the use of public transportation with zero emission system. Bus and subway are very convenient means for the people moving in the route areas. But they are not enough to satisfy handicapped or old people to have access to them and also do not solve environmental problems completely. New vehicle system, fuel cell track rapid transit, will be introduced as a countermeasure for such problems in the present paper.

• Electronics and Telecommunications Trends
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• v.5 no.3
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• pp.32-42
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• 1990

정보화 요구의 확산에 따라 최근에 와서 MAN(Metropolitan Area Network)의 관심도가 고조되고 있다. 본 고에서는 IEEE 802.6에서 표준화를 추진하고 있는 DQDB(Distributed Queue Dual Bus) MAN프로토콜의 구조에 대하여 간략히 서술하였고, 현재 표준화의 진척상황 및 어떠한 문제점들이 논의되고 있는지 알아보았으며, 또한 MAN이 충분한 서비스를 제공하기 위하여 앞으로 어떠한 사항들이 해결되어야 할 것인가에 대하여 언급하였다.

• Journal of the Korean Professional Engineers Association
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• v.40 no.6
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• pp.59-64
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• 2007

LRT(LAght Rail Transit) system is a new transportation system with new technique of an electric railway. Transportation ability of LRT is mid-scale of a bus and a subway, transporting 5,000-30,000 people per hour and direction. LRT automatically operates in the existing metropolitan railway and large-scale development areas or satellite cities with a fixed route and has a short interval that guarantees scheduled-time, safety and environment-friendly.

• Journal of the Korean Geographical Society
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• v.44 no.2
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• pp.176-186
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• 2009

Transportation policy to facilitate the public mode use is of the foremost importance to the local governments of Metropolitan Seoul, regarding the economic and environmental consequences of the increasing use of car. Understanding the travel behaviour is essential to the establishment of proper policy to guide more people to the use of public modes instead of private. The paper reports a result of sequential analysis of individual travel behaviour in Metropolitan Seoul, using a multi-dimensional motif search technique applied to Smart Card data that integrates individuals' different public mode uses. Groups of travel patterns with similar sequential information identified distinctive travel behaviour between Seoul north and south and between metro and bus uses. Travel patterns are more bounded within north Seoul and south Seoul respectively than crossing Han River between north and south. Within north and south, travel patterns visiting northern CBD and southern CBD, respectively, as well as their local neighbour in north and south, often use metro and metro-local bus combination, while travel patterns visiting only the north and south locals without CBDs more use only the local bus line and even only the areal bus line.

• Proceedings of the KIPE Conference
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• 2001.10a
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• pp.518-522
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• 2001

In recent years, natural energy has attracted growing interest because of environmental concerns. Many studies have been focused on photovoltaic power generation systems because of the ease of use in urban areas. On the conventional system, many photovoltaic modules (PV modules) are connected in series in order to obtain the sufficient DC-bus voltage for generating AC output voltage at the inverter circuit. However, the total generation power on the PV modules sometimes decreases remarkably because of the shadows that partially cover the PV modules. In order to overcome this drawback, an AC module strategy is proposed. On this system, a small power DC-AC utility interactive inverter is mounted on each PV module individually and the inverter operates so as to generate the maximum power from the corresponding PV module. This paper presents a novel flyback-type utility interactive inverter circuit suitable for AC module systems. The feature of the proposed system are, (1) small in volume and light in weight, (2) stable AC current injection, (3) enabling a small DC capacitor. The effectiveness of the proposed system is clarified through the simulation and the experiments.

• Nuclear Engineering and Technology
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• v.54 no.9
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• pp.3347-3352
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• 2022

In 2013, the International Atomic Energy Agency (IAEA) changed the recommended maximum range of the Emergency Planning Zone (EPZ) to 30 km, and the Kori Nuclear Power Plant in Republic of Korea has also expanded the EPZ to 30 km, following the recommendation. As a result, metropolitan cities with a high population density are contained within the EPZ, and evacuating millions of people should be considered if the 30 km range of evacuation is to take place. This study proposes an evacuation plan using buses (public transportation) to transport people outside of the EPZ, quickly and efficiently. To verify the appropriate mode share ratio of buses that can guarantee the right of vulnerable road users and reduce traffic congestion, a model was built simulating the Kori Nuclear Power Plant in Ulsan Metropolitan City. The scenarios were established by changing the mode share ratio of buses and passenger cars by 10%. Considering a large-scale network analysis at the city level, a cell transmission model was applied to calculate the evacuation time in each scenario. The result shows that the optimal mode share ratio of buses is 40%, with a total evacuation time of 132 min, considering feasible bus fleets in Ulsan Metropolitan City.