• Journal of Korean Society of Transportation
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• v.25 no.5
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• pp.195-207
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• 2007

The urban railways connecting between the inner city and suburb of Seoul metropolitan area, has lost the competitiveness against cars because too many stops deteriorated operating speed and passenger's level of service. This paper suggests that an express train should be introduced into the urban railway system in order to sort out such a complication. There are two considerations in the present study. Firstly, train schedule problem should be taken into account. In this regard, a new model for urban railway system was developed by revising the existing models dealing with single line freight railway. Approximate branch and bound algorithm based on conflict group rather than a single conflict was adopted. Consequently, it was found that the time saving in calculating the optimal schedule is the most meaningful contribution of the algorithm. The second consideration is associated with the application of the model. A case study was carried out using the actual operation data from Ansan line. In conclusion, the operation speed of the line can increase considerably with minimal number of new sidings.

• Journal of the Korean Society for Railway
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• v.13 no.3
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• pp.349-355
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• 2010

The purpose of this paper is to provide basic information on how to make better policies that improves efficiencies and to derive policy directions using DEA (data envelopment analysis) model. Through this paper, we can identify whether or not the railroad service has an excellent performance, if there are any structural problems, in which sector it is experiencing a degree of inefficiency, and, therefore, how to set up a realistic target to improve efficiency of railroad transportation. According to the result, we need to introduce a better resource efficient economic strategy to reduce the rail line extension and the number of passenger cars for better efficiency from a public interest perspective, while to widen headways and/or reduce the rail line extension from an economic point of view.

• Smart Structures and Systems
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• v.12 no.3_4
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• pp.415-426
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• 2013

Condition assessment and monitoring of bridges is critical for safe passenger travel, public transportation, and efficient freight. In monitoring, displacement measurement capability is important to keep track of performance of bridge, in part or as whole. One of the most important parts of a bridge is the expansion joint, which accommodates continuous cyclic thermal expansion of the whole bridge. Though expansion joint is critical for bridge performance, its inspection and monitoring has not been considered significantly because the monitoring requires long-term data using cost intensive equipment. Recently, a wireless smart sensor network (WSSN) has drawn significant attention for transportation infrastructure monitoring because of its merits in low cost, easy installation, and versatile on-board computation capability. In this paper, a rapid wireless displacement monitoring system, wireless hybrid sensor (WHS), has been developed to monitor displacement of expansion joints of bridges. The WHS has been calibrated for both static and dynamic displacement measurement in laboratory environment, and deployed on an in-service highway bridge to demonstrate rapid expansion joint monitoring. The test-bed is a continuous steel girder bridge, the Founders Bridge, in East Hartford, Connecticut. Using the WHS system, the static and dynamic displacement of the expansion joint has been measured. The short-term displacement trend in terms of temperature is calculated. With the WHS system, approximately 6% of the time has been spent for installation, and 94% of time for the measurement showing strong potential of the developed system for rapid displacement monitoring.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.16 no.5
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• pp.3455-3461
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• 2015

LTE and Wi-Fi networks provide wireless communication services to passengers in subway where the number of network access fluctuates according to passenger movement. While the number of network access increase, LTE can provide stable communication service but Wi-Fi suffers temporal access delay to network. This paper analyzes the increase in access delay of Wi-Fi network according to increasing user in subway section by making mathematical modeling of Wi-Fi network and simulation study. The access delay characteristics of Wi-Fi network is measured along an subway line and the results are compared to the theoretical study. These results can be applied to the connection method to build an efficient network structure between LTE and Wi-Fi interworking network and the future introduction of LTE-R.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.11 no.7
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• pp.2534-2540
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• 2010

In this paper we propose contents and results on installation and commissioning test for ATP on-board unit, which has propelled as one of the research projects, so called, "Reliability assessment and operation technology development for Korean-type tilting trains" in order to ensure the safety and operation efficiency of tilting trains. In KRRI, we have developed tilting trains for the speed-up of existing lines and for the passenger service improvement where the KTX is not available. And we also make progress the operation trial test at the speed of 10km with the use of ATS units, used in existing lines, for the purpose of the reliability assessment of the developed tilting trains. In MLTM, they have decided to accelerate the speed at more than 200km/h for the 7 existing lines including Jungang-line and Chungbuk-line where KTX has not operated. According to this decision, Train control system is to be changed from ATS to ATP. We should install an ATP on-board unit in tilting trains and verify the operational suitability. Therefore, we have installed and tested the same ATP on-board unit on tilting trains that used in the ATP construction project on Gyeongbu-line and Honam-line.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2014.10a
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• pp.917-920
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• 2014

In Korea mobile phone subscribers exceeded 1 million people in 1995, and ten million people in 1998. Prevalence of the mobile phone increased dramatically over 110% compared to the population. And all family members including children and students use one or two mobile terminal. Mobile phone is obviously necessary good more than washer, vacuum cleaner, passenger car. Our daily life with mobile communication are conveniently positioned, but communication related costs including the price of the device has become a big burden on the household. But the government does not seem to do the right role at the right time to prevent the failure of the market to further maximize consumer welfare and social welfare through fair competition. This principal-agent problems exist especially in perspective of joint use of the mobile communication network, number portability, separation of phone distribution and phone service and network neutrality among in mobile communication policies since the early 1990s up to now.

• Journal of Advanced Navigation Technology
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• v.23 no.2
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• pp.104-113
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• 2019

There are keen competitions among the air operators to recruit competent pilots, which could be adversely affect the safe operation of aircraft. This study is aimed to identify the correlation between the flight experience of the pilot of the air transport operator and competency on visual approach operation. About 2,400 sets of flight training data of several pilots of an air transport operator was analysed for this study. The analysis showed that most captains were able to make stabilized visual approach regardless of his/her flight experience of any type of aircraft, while the first officers were able to make a stabilized visual approach with more than 1,500 hours of flight experience for each rated type of aircraft. This should be considered during making policies for the supply and demand of pilots for the safe operation of air transport.

• The Korean Journal of Emergency Medical Services
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• v.23 no.1
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• pp.61-69
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• 2019

Purpose: The study aims to provide basic data to enhance the health of paramedics responsible for patient transport and treatment by analyzing the exposure level of paramedics to electromagnetic waves generated by electric devices used in ambulances. Methods: The study measured electromagnetic waves in ambulances in N region from July to December 2018. ME3030B produced by German Gigahertz Solutions was used to measure these waves and the maximum value was selected by moving it slowly in various directions. Each measurement part was selected and the mean value was calculated by repeatedly measuring at 10-minute intervals three times in total: $1^{st}$, $2^{nd}$, and $3^{rd}$ phase. Results: Among the electrical devices installed in the patient room of the ambulance measured at distances of 1 cm or 30 cm, results showed a high level of electric waves at the inverter ($26.25{\pm}39V/m$) and high level of electromagnetic waves ($564.00{\pm}31.75nT$) at the ozone sterilizer. According to measurements toward the front near the driver's seat, results indicated high levels of electric waves ($3.67{\pm}1.15V/m$) and electromagnetic waves ($450.00{\pm}19.52nT$) at the black box hard drive. Conclusion: Electromagnetic waves within the ambulance were stable and not beyond the range that might impact human health. However, in the case of the black box hard drive ($3.67{\pm}1.15V/m$, $450.00{\pm}19.52nT$) located under the passenger seat, it may have a direct effect on the human body and, thus it is necessary to move it to a storage area further away from the paramedics to minimized the impact.

• Convergence Security Journal
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• v.20 no.4
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• pp.217-225
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• 2020

In recent years, the "social distance" has drastically reduced overseas travelers. On the other hand, for personal safety and security, it is expected that interest and demand for CCTV, electric alarm and signaling devices, electric diagnostics and medical devices will increase significantly. The purpose of this paper is to find out the effect of airport transfer passengers and exports of CCTV, electrical diagnostics and medical devices, electrical alarms and signaling devices on exports to Korea, and the synchronism of each variable. To this end, this study used a total of 231 monthly data from January 2000 to April 2020 in the National Statistics Service. As a result of empirical analysis, CCTV and electrical diagnostics and medical devices showed relatively high synchronization with respect to exports to Korea. Electric alarms & signaling devices and transit passengers also showed a certain level of synchronization with exports, but were relatively weak.

• Journal of Advanced Navigation Technology
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• v.27 no.3
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• pp.255-261
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• 2023

A main purpose of this research was to analyze environmental factors to influence helicopter accidents contrary to the fact that the almost 80% of helicopter accidents happened due to pilots' human errors. There have been about 14 helicopter accidents in civil aviation sector last decade. It is noteworthy that nine of 14 accidents happened during the external sling load operation. Moreover, there is no law or regulation which could cover the helicopter external sling load operation or human external cargo in Korea. In this paper, it was analyzed the training and education regulations regarding helicopter external sling load operation or human external cargo in regulations of FAA and EASA, Based on analyzing and comparing the FAR part 133 and domestic aviation law (aviation safety act and flight safety regulations), it was found out the implication how to apply helicopter type rating for external sling load operation and human external cargo operation. To sum up, this paper expect central government should cooperate and amend aviation law which apply external sling load operation and external cargo to establish sound safety culture in Korea.