• Journal of Energy Engineering
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• v.21 no.2
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• pp.144-151
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• 2012

A district heating system produces thermal energy and supplies it to a large region. District heating systems can provide higher efficiencies and better pollution control than localized boilers. The heat generated by a district heating system is distributed to the customer via a network of insulated pipes. For the optimal operation of a district heating system, it is important to predict the distributions of pressure, flow rate and temperature of heating fluid within the network of pipes at various operating conditions. In this work, a mathematical modeling was performed to predict the dynamic hydraulic-thermal behaviors of heating fluid in the network of pipes for a district heating system. The mathematical model accounts for the conservations of mass, momentum and energy. In order to verify the validity of modeling, the modeling results were compared with the monitoring data of Gang-nam Branch of District Heating.

• KIEAE Journal
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• v.13 no.5
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• pp.17-22
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• 2013

This study aims at proposing a sound and sustainable development direction of an urban commercial district by identifying space syntactic properties, from the perspective of human ecology, of the street network in Enuengjeongi culture street as the representative commercial district of Daejeon City in Korea. The results are obtained through Angular Segment Analysis (ASA) on the street network in subject area for this study. It was found that most of the socially integrated nodes are arranged along the axis of main street in the district. However, in some of those nodes, it was investigated that the social integrative function have weakened, because open spaces as public space for the general public are occupied illegally by commercial purposes of shops and car parking. It was found that the socially isolated nodes are located at the district boundary connected to a relative narrow street, with a relatively low density of the commercial facilities. Besides, it was identified that a street width in the commercial district may be a factor affecting the social integration of a space on the basis of the openness of the space.

• Journal of Energy Engineering
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• v.26 no.3
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• pp.123-130
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• 2017

The district heating system has been successfully implemented with higher efficiency levels of energy production and reduction of carbon emissions during heat generation. Traditionally the system consisted of small number of production and demand sites, but, recently it has evolved into a network with large number of sites interconnected each other. By connecting multiple sites into a network, heat from low-cost production sites can be supplied to distant demand sites so as to lower the total operation cost. In this study, we simulate and analyze distict heating networks focused on critical links. a critical link is defined as a link in which capacity is fully utilized. If a newtork has critical links, then those cricial links become bottlenecks and it is difficult to improve the overall network efficiency.

• Journal of Information Processing Systems
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• v.19 no.1
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• pp.130-138
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• 2023

The traffic flow in an urban area is affected by the date, weather, and regional traffic flow. The existing methods are weak to model the dynamic road network features, which results in inadequate long-term prediction performance. To solve the problems regarding insufficient capacity for dynamic modeling of road network structures and insufficient mining of dynamic spatio-temporal features. In this study, we propose a novel traffic flow prediction framework called shared spatio-temporal attention convolution optimization network (SSTACON). The shared spatio-temporal attention convolution layer shares a spatio-temporal attention structure, that is designed to extract dynamic spatio-temporal features from historical traffic conditions. Subsequently, the graph optimization module is used to model the dynamic road network structure. The experimental evaluation conducted on two datasets shows that the proposed method outperforms state-of-the-art methods at all time intervals.

• Proceedings of the Korea Water Resources Association Conference
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• 2021.06a
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• pp.147-147
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• 2021

A partition of water distribution network (WDN) into district metered areas (DMAs) brings the efficiency and efficacy for water network operation and management (O&M), especially in monitoring pressure and leakage. Traditionally, the DMA configurations (i.e., number, shape, and size of DMAs) are permanent and cannot be changed occasionally. This leads to changes in water quality and reduced network redundancy lowering network resilience against abnormal conditions such as water demand variability and mechanical failures. This study proposes a framework to automatically divide a WDN into dynamic DMA configurations, in which the DMA layouts can self-adapt in response to abnormal scenarios. To that aim, a complex graph theory is adopted to sectorize a WDN into multiscale DMA layouts. Then, different failure-based scenarios are investigated on the existing DMA layouts. Here, an optimization-based model is proposed to convert existing DMA layouts into dynamic layouts by considering existing valves and possibly placing new valves. The objective is to minimize the alteration of flow paths (i.e., flow direction and velocity in the pipes) while preserving the hydraulic performance of the network. The proposed method is tested on a real complex WDN for demonstration and validation of the approach.

• KIEAE Journal
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• v.13 no.2
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• pp.151-156
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• 2013

This study examines the properties of spaces where historical and cultural resources have been preserved in the street system of Daegu Yakryeong market district, by using Space Syntax methodology. The results were obtained through ASA(Angular Segment Analysis) on each node (spatial unit) in the street network. An overall characteristic of spatial configuration in street system of the surveyed district is that nodes in the street network tend to form socially integrated spatial structure to allow easy access to each space in the system. There are a small number of socially isolated spaces in the street system, which are located at nodes in narrow streets adjacent to the roadway outside the district, or in narrow alleys between early modern Korean buildings. More than half of the surveyed spaces have high levels of social integration, which contain buildings playing a central role of the community, a traditional street market, symbolic landmarks. In conclusion, it is expected that the achievements of this study will contribute in leading to rational land use planning for sound and sustainable development of historical and cultural resources in an urban district.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.12 no.4
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• pp.1-10
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• 2009

This study has intended to build ecological networks in consideration of life-zones inside Cheongju city through biotope grade, GIS network analysis etc. This study consisted of following three steps. First, we selected core districts and core spot districts using land use patten and biotope grade. The core district included the first grade of biotope and forest land. The core district consisted of two sectors : east axis core, Uam mountain; west axis core, Bumo mountain. The core spot district included the first grade of biotope. The core spot districts consisted of two sectors : north axis base core, Myongshim park; south axis base core, Guryong park. Second, the base district included the second grade of biotope and park and school. We used buffering analysis within 500m of the base district and selected the new base district. Third, we connected core districts and base core districts using least cost analysis of GIS. Thus we built comprehensive ecological networks in consideration of life-zones through GIS.

• Proceedings of the SAREK Conference
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• 2004.11a
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• pp.59-59
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• 2004

• Proceedings of the SAREK Conference
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• 2005.06a
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• pp.119-119
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• 2005

• Knowledge Management Research
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• v.11 no.1
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• pp.51-64
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• 2010

The exhibition and convention industries, which are recognized as industrial hub linked with many relational industries. It is important to prevent a excessive competition for convention centers among districts and to gain some benefit fairly. Each convention center needs a lot of convention to held in it's district. In order to obtain many conventions to held in Korea for many convention center, convention bureau has to manage the processes to attract convention with many collaborators using the convention hub-network system. We should, therefore, pay attention to construction of the convention Hub-Network system to activate the convention industries in the district. We lay out the critical design for three functions of the convention Hub-Network system using UML. Finally we show the demonstrative web pages that explain critical three functions.