• Nuclear Engineering and Technology
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• 제49권1호
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• pp.134-140
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• 2017

A well-performed core power control to track load changes is crucial in pressurized water reactor (PWR) nuclear power stations. It is challenging to keep the core power stable at the desired value within acceptable error bands for the safety demands of the PWR due to the sensitivity of nuclear reactors. In this paper, a state-space model predictive control (MPC) method was applied to the control of the core power. The model for core power control was based on mathematical models of the reactor core, the MPC model, and quadratic programming (QP). The mathematical models of the reactor core were based on neutron dynamic models, thermal hydraulic models, and reactivity models. The MPC model was presented in state-space model form, and QP was introduced for optimization solution under system constraints. Simulations of the proposed state-space MPC control system in PWR were designed for control performance analysis, and the simulation results manifest the effectiveness and the good performance of the proposed control method for core power control.

• Ocean and Polar Research
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• 제24권4호
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• pp.419-427
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• 2002

Meiobenthic community structure near Dokdo was investigated during two survey periods of June, 1999 and October 2000. Meiobenthos were separated from the sediment core samples collected from eight stations. A total of 19 meiobenthic animal groups were identified from those core samples. The most abundant meiobenthic animals belonged to Phylum Nematoda in both seasons and all stations. Sarcomastigophorans, nauplius of crustaceans, and benthic harpactiocoids were the next abundant meiobenthos. Vertical distribution of meiobenthic animals showed the highest individual numbers in the surface sediment layers of 0-1cm depth with a steep decreasing trend with depth for the three sampling stations (A0, A9', A19) located in the continental slope. Horizontal distribution of meiobenthic animals for the study area near Dokdo showed lower density at the sampling stations near Dokdo and the lowest density of meiobenthos in A19 (depth-2261 m). For size distribution, analysis showed that animals which fit onto the mesh size of 0.125mm were abundant. This study suggested that the continental shelf near Dokdo have a more unstable environment fo meiobenthos than the continental slope.

• 철도저널
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• 제19권6호
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• pp.29-36
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• 2016

• 한국수소및신에너지학회논문집
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• 제27권3호
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• pp.256-263
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• 2016

As the hydrogen era comes near future, hydrogen fuel cell vehicles are core of hydrogen economy. Until now, Korea has 17 hydrogen refueling stations but 9 hydrogen refueling stations have been retired already and 8 hydrogen refueling stations are still running. With a limited number of hydrogen refueling stations, it is very difficult to get scientific data for the economy of hydrogen refueling stations in Korea. Thus, based on NREL(National Renewable Energy Laboratory) study, we analyzed most recent data for the construction of hydrogen refueling stations in one specific site in Korea. The cost comparison data between Korea and USA shows 14% difference, saying higher costs of Korea. Korea looks 5 years delay compared to USA. This data will be an important tool for the investment from every industrial parties.

• KSII Transactions on Internet and Information Systems (TIIS)
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• 제14권8호
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• pp.3366-3383
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• 2020

The Poisson point process (PPP) is widely used in wireless network modeling and performance analysis because it can provide tractable results for heterogeneous cellular networks (HetNets) analysis. However, it cannot accurately reflect the spatial distribution characteristics of the actual base stations (BSs). Considering the fact that the distribution of macro base stations (MBSs) is exclusive, the deployment of MBSs is modeled by the Matérn hard-core point process (MHCPP), and the deployment of pico base stations (PBSs) is modeled by PPP. This paper studies the performance of multiantenna HetNets and improves the energy efficiency (EE) of HetNets by optimizing the transmit power of PBSs. We use a simple approximate method to study the signal-to-interference ratio (SIR) distribution in two-tier MHCPP-PPP HetNets and derive the coverage probability, average data rate and EE of HetNets. Then, an optimization algorithm is proposed to improve the EE of HetNets. Finally, three transmission technologies are simulated and analyzed. The results show that multiantenna transmission has better system performance than single antenna transmission and that selecting the appropriate transmit power for a PBS can effectively improve the EE of the system. In addition, two-tier MHCPP-PPP HetNets have higher EE than two-tier PPP-PPP HetNets.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2008년도 추계학술대회 논문집
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• pp.698-705
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• 2008

Under the rapid change in environment of our society and culture, it is also called for a reform in railway management that has traditionally focused on transportation service. Thus developing a business model to use station buildings as a new source of profit has become a promising core business of railway companies. This study aims to find a way to maximize profits by strategically utilizing station buildings and thereby increasing accessibility to customers and consolidating facilities as a key service point. The subjects of this study include eight station buildings that can represent three types of railway stations including departure stations, junction stations, and metro stations. The researcher conducted an analysis on moving lines for examining user distribution and facility utilization within the selected buildings, a survey for collecting basic information on usage and measuring customer satisfaction of facility in the buildings, and a sight analysis to examine accessibility to the station buildings. On the basis of these analyses, the researcher examined the correlations between convenience, visibility, recognizability and functionality with regard to commerce, amenities, couches, direction boards, etc. within station waiting rooms. On the basis of the above analyses, the researcher provides a scheme to increase profitability in railway operation business and customer benefits of using station buildings by drawing up a plan to improve usage of station buildings and maximize profit-making potential for each category of station buildings.

• 국제초고층학회논문집
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• 제12권1호
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• pp.63-74
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• 2023

Large-capacity public transportation systems, represented by urban metro lines, are the key to alleviating the significant increase in urbanization and motorization in China. But to improve the agglomeration effect of metro stations in a more accurate and targeted way requires scientific evaluation and classification of the surrounding areas of metro stations. As spatial and functional design are the core factors for urban renewal design, this study took Beijing as an example, using multi-source data to evaluate the morphology and functional composition surrounding areas of metro stations, and the Boston Consulting Group (BCG) matrix was used to classify and characterize each type of surrounding areas from morphological-functional dimensions. It shows a negative correlation of the mix-use index with the floor area ratio, and only about 20% of the areas achieve the ideal situation of high construction intensity with high mix-use diversity. Hoping to provide a reference for city managers and designers in dealing with the surrounding metro stations with different construction intensities in a more precise way.

• 한국철도학회논문집
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• 제9권3호
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• pp.282-290
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• 2006

In the current train operation system, large scaled stations like Cheongnyangni and Yongsan are not remote controlled from the central operator but manually by local operator. It is because there are so many entering and exit of trains between depot and mainline which are operating through the large scaled stations and it is very effective to traffic flow on the mainline. Therefore, Kyong Bong Technology Co., Ltd. (KBTech) and Korea Railway Research Institute (KRRI) are continuing the research and development to import 'Autonomous Decentralized System (ADS)'as part of a new train operation control system which is a national policy project of MOCT (Ministry Of Construction & Transportation). The concept of the 'Autonomous Decentralized System (ADS)' has born in 1970's in Japan by the influences of molecular biology. The special features of ADS are being a system that able to do the online expansion, online maintenance and fault tolerance. This thesis introduces the concept of technology of ADS and also describes the system designing & development to apply with large scaled stations.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2010년도 춘계학술대회 논문집
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• pp.703-721
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• 2010

친환경 녹색성장 대표 교통수단인 철도는 자동차와는 달리 연계환승 체계가 꼭 필요한 교통수단이다. 이에 주요 철도거점역을 중심으로 하는 연계체계의 필요성은 국가적인 핵심 사업으로 필요하게 될것이다, 따라서 이용고객의 환승체계의 시스템이 이루어지지 않으면 녹색성장 및 대중교통 활성화 서비스는 멀게만 느껴질것이다. 아울러, 본 연구에서는 경남지역 철도거점역(창원, 북창원, 마산) 과 타 교통수단간 연계 환승 구축 및 활성화 방안을 소개하고자 한다. 이 방안은 지역거점역의 연계환승체계 구축 모델이 될 수 있을것으로 판단되며, 철도 대중교통 이용고객 편의를 위한 방안으로 적용이 가능할 것으로 판단된다.

• 산업공학
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• 제14권3호
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• pp.318-325
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• 2001

In this paper, we estimate the investment cost for the IMT-2000 services in Korea. The network elements for the IMT-2000 system are drawn out and the required number of base stations(Node-B) is predicted by using the coverage of the base station. With the assumption of the 2-generation mobile communications network configuration, the number of radio network controllers(RNC's) and core network facilities is estimated. We also setup different scenarios by considering the utilization of the transmission facilities between base stations, RNC's and switching systems, and then evaluate the investment cost for each scenario.