• The Journal of the Korea Contents Association
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• v.22 no.10
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• pp.526-534
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• 2022

In August 2014, the Ministry of Land, Infrastructure, and Transport (MOLIT) devised an innovative ITS measure in which private and public sectors share roles to maximize investment efficiency and effectiveness in collecting and offering traffic information that had been separately implemented by the state and private sector. The main details of the innovative measure include the following: For communication information, the information collected by the private sector is used, and the state concentrates on safety-related information collection, such as unexpected situations, including construction, accidents, and deteriorating weather conditions. Consequently, safety-related information is offered in real-time through smartphones and navigation, in addition to electric road signs that have limitations in providing unexpected real-time situations due to installation at specific spots. This study presented a connected traffic information priority coordination plan to improve the accuracy of traffic information offering by analyzing problems of related traffic information, including a general national highway case study to enhance the efficiency of national highway ITS implementation, according to actual public-private traffic information sharing. In addition, this study reviewed whether to operate or demolish the information collection equipment by analyzing traffic volume level and availability of related traffic information in the existing ITS operation sections and presented ITS collection equipment installation judgment standards based on the cases concerned.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2004.11a
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• pp.237-240
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• 2004

For the paralleled operation of DC/DC converters, the current sharing between each modules is the most important for the reliability of the power system. Interleaving method is commonly used with many paralleling schemes for the reduction of the ripple in the output voltage of paralleled converters and there are many commercial IC for interleaving application appliable. But for all of them, it is impossible to detect the number of module in operating and then change the phase of them automatically. In this paper, a novel paralleling method is proposed for the converter parallel operation, which detects the number of modules in active and sets the phases of PWM signals applied to each modules autonomously. This can greatly improve the output voltage ripple and reliability of the system. The expandibility of modular number can be done very easily by just adding several parts.

• Proceedings of the Korean Institute of IIIuminating and Electrical Installation Engineers Conference
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• 2007.05a
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• pp.235-240
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• 2007

A large power fuel cell generation system needs a parallel operation of de-de boost converter. Therefore, this paper proposed parallel operation algorithms of de-de boost converters for the large scale fuel cell generation system of 250[kW] and the operating principle along with the control method in detail. This paper uses a maximum current sharing method as a parallel operation method and also the phase shift full bridge de-de converter as a de-de boost converter. Simulation and experimental results on two prototype converter modules of 500W show that the parallel operation method can be applied to the 250[kW] power converter.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.23 no.11
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• pp.44-51
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• 2009

A variety of Urban Rail Transit (URT) systems have been operating and they have different technology bases, causing a lot of difficulties in taking measures against trouble, training, upgrading, interoperability and so on. As such, a standardization project has been carried out to solve the problems by setting up the national standards for URT systems. A common database was built to provide the integrated engineering environment to the community of URT project. This paper discusses the design of the database and how it can be utilized in the successful promotion of the project. The products of the projects are stored into the database with traceability management to be referred to by other new URT projects for reusing and sharing the acquired knowledge through cross organizations.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.28 no.5
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• pp.68-75
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• 2014

Cascaded applications of surge protective devices(SPDs) are required in order to reduce the stress on the electrical and electronics equipment being protected, and the energy coordination between the cascaded SPDs is very important. This paper deals with the experimental results obtained from the installation conditions of full-scale SPDs. The energy coordination between the upstream Class I SPD and the downstream Class II SPD was measured using a $10/350{\mu}s$ impulse current due to direct lightning flashes. The distances between the cascaded SPDs were 3, 10, and 50m, and the maximum test current was 12.5kA. As a result, the energy sharing between cascaded SPDs was dependent on the voltage protection level of each SPD and the distance between two SPDs. An overview of how to select SPD ratings in applications of cascaded SPDs system was discussed based on the energy coordination between the two SPDs. The proposed test results for the energy coordination between two-stage cascaded SPDs can be used in effective applications of SPDs.

• Advances in Energy Research
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• v.8 no.4
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• pp.243-252
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• 2022

The hybrid wind-solar energy concept has a big influence on the spread of wind and solar power projects in India since it combines the benefits of both industries while also providing extra benefits such as resource sharing such as land, infrastructure, and power evacuation systems. Furthermore, while the hybrid policy may reduce certain barriers to the installation of wind and solar energy in India, there are still some issues that must be resolved rapidly in order to ensure a sustainable installation. According to the study's findings, the installation of wind and solar power plants is significantly influenced by energy policy. The wind-solar hybrid energy strategy will also be crucial in the near future for growing the usage of renewable energy sources. Aside from that, the establishment of Green Energy Open Access (GEOA) and the restart of the trading of Renewable Energy Certificates (REC) would promote the quick deployment of standalone and hybrid renewable power projects throughout the nation, enabling it to reach 500 GW of installed non-fossil energy capacity by 2030.

• Journal of the Korean Institute of Illuminating and Electrical Installation Engineers
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• v.29 no.6
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• pp.70-77
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• 2015

This paper describes the experimental results obtained from various installation conditions of cascaded metal oxide varistor(MOV)-based SPDs with the objectives to analyze the coordination of the cascaded surge protective devices(SPDs) and to propose the proper selection and installation methods of the cascaded SPDs. The residual voltage, discharge current and energy sharing between the upstream and downstream SPDs in the $10/350{\mu}s$ direct lightning current wave were measured and discussed. The coordination of cascaded MOV-based SPDs is closely related to the varistor voltage and installation methods of SPDs. In cascaded SPDs without dedicated decoupling elements, the natural impedance of leads connecting two SPDs can act as a decoupler for the coordination of MOV-based SPDs. Even if the varistor voltage of the upstream SPD is higher than that of the downstream SPD at long distances between two SPDs, the energy coordination of cascaded SPDs could effectively be fulfilled in the conditions of large surge currents and the optimum voltage protection level can be achieved. Consequently, if the distance between voltage limiting type SPDs is long, the coordination of the cascaded SPDs should be determined by taking into account the decoupling effects due to the intrinsic inductance of leads connecting the upstream and downstream SPDs.

• KSCE Journal of Civil and Environmental Engineering Research
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• v.34 no.5
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• pp.1517-1524
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• 2014

In recent years, the interest of environmental-friendly transportation modes has been growing. This is because of social and environmental problems such as increasing gas price and climate change. In Europe, bike-sharing service, one of the environmental-friendly transportation modes, has been already operated. Bike-sharing service named "Tashu" has been operated in Daejeon city since 2009. This study is a fundamental research to increase utilization efficiency of bike-sharing service and to decide optimal locations of bike stations. In addition this study examines characteristics of bike usage and analyzes factors affecting to demands using multiple regression model. Based on the result of examining of characteristics of bike usage, the rate of bike usage is higher compared with installation rate of public bike stations near parks in Daejeon. In addition demands of bike usage in weekend is higher than in weekday. It reveals that the main purpose of bike usage could be recreational activities. The return rate at the same location with rental station is comparatively high. Moreover, bike usage pattern is biased in specific areas (Dunsan and Yuseong) because bike-sharing stations are not equally located. As a result of multiple regression model, the factors affecting to demands are number of passengers in buses, length of bike lanes, parks, distance to waterfront, and rate of young people. A statistical significance of factors (r-square) is 0.748, which has strong relationship.

• Geomechanics and Engineering
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• v.18 no.4
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• pp.363-371
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• 2019

In this study, the load carrying behavior of piled rafts installed in inclined bearing rock layer was investigated for rock-mounted and -socketed conditions. It was found that settlements induced for an inclined bearing rock layer are larger than for a horizontal layer condition. The load capacity of piled rafts for the rock-mounted condition decreased as rock-layer inclination angle (${\theta}$) increased, while vice versa for the rock-socketed condition. The load capacities of raft and piles both decreased with increasing ${\theta}$ for the rock-mounted condition. When bearing rock layer was inclined, loads carried by uphill-side piles were greater than those by downhill-side piles. The values of differential settlements of rock-mounted and -socketed conditions were not significantly different whereas slightly higher for the rock-socketed condition. The values of load sharing ratio (${\alpha}_p$) and its variation with settlement were not markedly changed by the inclination of bedrock. It was shown that ${\alpha}_p$ for piled rafts installed in rock layer was not affected by ${\theta}$ whereas actual loads carried by raft and piles may vary depending on the pile installation and rock-layer inclination conditions.

• IE interfaces
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• v.13 no.3
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• pp.444-454
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• 2000

Due to the improvement of modern information technologies, sharing stock information among the supply chain members is a common practice nowadays. Many companies are planning to adopt the information systems to possess the real-time shared stock information. Thus, it is needed to quantify the value of shared stock information. The purpose of this paper is to evaluate the value of the shared stock information for two-echelon distribution systems. Existing reorder policies can be classified into installation stock policies and echelon stock policies. Since installation stock policies do not utilize the shared stock information, and both classes of policies may show poor performances for distribution systems, we cannot evaluate the value of the shared stock information with the existing policies. Thus, we provide a new type of reorder policy, named order risk policy. We define the order risk using marginal analysis, and prove the optimality. Through computational experiment that compares the order risk policy with the existing policies, it is shown that a significant cost reduction is achieved with the effective utilization of the shared stock information. We also show the effect of the system characteristics on the value of the shared stock information.