• Journal of Korean Tunnelling and Underground Space Association
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• v.19 no.1
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• pp.11-27
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• 2017

The road network system of major domestic urban areas such as city of Seoul was rapidly developed and regionally expanded. In addition, many kinds of life-lines such as electrical cables, telephone cables, water&sewerage lines, heat&cold conduits and gas lines were needed in order for urban residents to live comfortably. Therefore, most of the life-lines were individually buried in underground and individually managed. The utility tunnel is defined as the urban planning facilities for commonly installing life-lines in the National Land Planning Act. Expectation effectiveness of urban utility tunnels is reducing repeated excavation of roads, improvement of urban landscape; road pavement durability; driving performance and traffic flow. It can also be expected that ensuring disaster safety for earthquakes and sinkholes, smart-grind and electric vehicle supply, rapid response to changes in future living environment and etc. Therefore, necessity of urban utility tunnels has recently increased. However, all of the constructed utility tunnels are cut-and-cover tunnels domestically, which is included in development of new-town areas. Since urban areas can not accommodate all buried life-lines, it is necessary to study the feasibility assessment system for utility tunnel by urban patterns and capacity optimization for urban utility tunnels. In this study, we break away from the new-town utility tunnels and suggest a quantitative assessment model based on the evaluation index for urban areas. In addition, we also develop a program that can implement a quantitative evaluation system by subdividing the feasibility assessment system of urban patterns. Ultimately, this study can contribute to be activated the urban utility tunnel.

• Journal of the Korean Association of Geographic Information Studies
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• v.20 no.3
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• pp.52-66
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• 2017

This study aims at designing standard metadata that can be incorporated for advanced utilization of damage prediction maps, and thereby constructing the standard meta-information management prototype system on the basis of the proposed design. Based on the ISO/TC 211 19115 international standard, which is considered as the most widely used standard (as per the results of a domestic and foreign metadata standard survey), the designing process for the standard metadata was established and the metadata was categorized into nine classes. Additionally, based on the output of the standard metadata design process, a standard meta-information management prototype system, capable of checking and downloading meta-property information, was constructed using the JAVASCRIPT language. By incorporating the obtained results, it is possible to maintain the quality of the constructed damage prediction map by establishing a standardized damage prediction map database. Furthermore, disaster response can be actuated through the provision and management of data for effective operation of the proposed damage prediction system.

• KOREAN JOURNAL OF CROP SCIENCE
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• v.27 no.4
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• pp.296-313
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• 1982

At a time when world population and food supply are in a delicate balance, it is essential that we look at factors to improve this balance. We can alter the environment to better fit the plant's needs, or we can alter the plant to better fit the environment. Improved technology has allowed us to increase the yield level. For moderately detrimental weather events technology has generally decreased the yield variation, yet for major weather disasters the variation has increased. We have raised the upper level, but zero is still the bottom level. As we concentrate the production of particular crops into limited areas where the environment is closest to optimum, we may be increasing the risk of a major weather related disaster. We need to evaluate the degree of variability of different crops, and how weather and technology can interact to affect it. The natural limits of crop production are imposed by important ecological factors. Production is a function of the climate, the soil, and the crop and all activities related to them. In looking at the environment of a crop we must recognize these are individuals, populations and ecosystems. Under intensive agriculture we try to limit the competition to one desired species. The environment is made up of a complex of factors; radiation, moisture, temperature and wind, among others. Plant response to the environment is due to the interaction of all of these factors, yet in attempting to understand them we often examine each factor individually. Variation in crop yields is primarily a function of limiting environmental parameters. Various weather parameters will be discussed, with emphasis placed on how they impact on crop production. Although solar radiation is a driving force in crop production, it often shows little relationship to yield variation. Water may enter into crop production as both a limiting and excessive factor. The effects of moisture deficiency have received much more attention than moisture excess. In many areas of the world, a very significant portion of yield variation is due to variation in the moisture factor. Temperature imposes limits on where crops can be grown, and the type of crop that can be grown in an area. High temperature effects are often combined with deficient moisture effects. Cool temperatures determine the limits in which crops can be grown. Growing degree units, or heat accumulations, have often been used as a means of explaining many temperature effects. Methods for explaining chilling effects are more limited.

• Journal of Korean Society of societal Security
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• v.3 no.2
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• pp.57-64
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• 2010

In this study, the behavior and safety of an existing tunnel and its facilities are investigated when a new tunnel adjacent to the existing tunnel is blasted. The design of the new tunnel puts priority on stability of the tunnel itself over the safety of the facilities which are installed within the existing tunnel such as jet fans. And thus, a detailed consideration on securing the safety of the existing facilities has been insufficient. An analysis on the types of traffic accidents in the last ten years shows that most incidents were due to the driver's improper response in emergency situations and unexpected obstacles. In consideration of this analysis, the safety of the facilities in the existing tunnel was secured by minimizing the charging amount for each hangfire and changing the excavation method of evacuation communication shelters to the large center hole cut blasting method to reduce blasting vibration. For a more quantitative analysis, measurement devices were installed inside the existing tunnel, at houses adjacent to the new tunnel, near jet fans in the existing tunnel. This enabled real time measurement of displacements of the existing tunnel, adjacent houses, and jet fans without interrupting traffic flow. Therefore, the improvements of charging amount for each hangfire, the blasting method, and the measurement method are suggested in this paper to secure the safety of the facilities in the existing tunnel when a new tunnel, located on a large city and adjacent to an existing tunnel, is designed.

• Journal of the Korea Concrete Institute
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• v.28 no.5
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• pp.535-544
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• 2016

This paper aims at examining the effects of sustained load and elevated temperature on the time-dependent deformation of a carbon fiber reinforced polymer (CFRP) sheets bonded to concrete as well as the pull-off strength of single-lap shear specimens after the sustained loading period using digital images. Elevated temperature during the sustained loading period resulted in increased slip of the CFRP composites, whereas increased curing time of the polymer resin prior to the sustained loading period resulted in reduced slip. Pull-off tests conducted after sustained loading period showed that the presence of sustained load resulted in increased pull-off strength and interfacial fracture energy. This beneficial effect decreased with increased creep duration. Based on analysis of digital images, results on strain distributions and fracture surfaces indicated that stress relaxation of the epoxy occurred in the 30 mm closest to the loaded end of the CFRP composites during sustained loading, which increased the pull-off strength provided the failure locus remained mostly in the concrete. For longer sustained loading duration, the failure mode of concrete-CFRP bond region can change from a cohesive failure in the concrete to an interfacial failure along the concrete/epoxy interface, which diminished part of the strength increase due to the stress relaxation of the adhesive.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.11
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• pp.728-739
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• 2020

Using webometric big data, this study examines the diversity of online information sources about the novel coronavirus causing the COVID-19 pandemic. Specifically, it focuses on some 28 countries where confirmed coronavirus cases occurred in February 2020. In the results, the online visibility of Australia, Canada, and Italy was the highest, based on their producing the most relevant information. There was a statistically significant correlation between the hit counts per country and the frequency of visiting the domains that act as information channels. Interestingly, Japan, China, and Singapore, which had a large number of confirmed cases at that time, were providing web data related to the novel coronavirus. Online sources were classified using an N-tuple helix model. The results showed that government agencies were the largest supplier of coronavirus information in cyberspace. Furthermore, the two-mode network technique revealed that media companies, university hospitals, and public healthcare centers had taken a positive attitude towards online circulation of coronavirus research and epidemic prevention information. However, semantic network analysis showed that health, school, home, and public had high centrality values. This means that people were concerned not only about personal prevention rules caused by the coronavirus outbreak, but also about response plans caused by life inconveniences and operational obstacles.

• Journal of the Korean Society of Radiology
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• v.3 no.4
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• pp.35-38
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• 2009

Flat-panel x-ray detectors using a phosphor and photoconductor material have been used for application in various medical modalities. In this study, the monte carlo simulation, optical and x-ray response characteristics were investigated in the conversion structure obtained by a columnar CsI:Na scintillation layer with a photosensitive amorphous selenium layer. Firstly, from the measurement of luminescent spectrum of CsI:Na and absorption spectrum of a-Se layer, the signal conversion characteristics are analysed. And also, the x-ray sensitivity is measured and compared with conventional a-Se($500{\mu}m$) as a function of electrical field. From the experimental result, the x-ray sensitivities of the CsI:Na($180{\mu}m$)/a-Se($30{\mu}m$) detector and the a-Se($500{\mu}m$) detector were $7.31nC/mR-cm^{2}$ and $3.95nC/mR-cm^{2}$at an electric field of $10V/{\mu}m$, respectively.

• Journal of Korean Society of Environmental Engineers
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• v.32 no.5
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• pp.487-498
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• 2010

This article presents an effect of deicer such as $CaCl_2$(calcium chloride) and EFD(Eco-Friendly Deicer) composed by organic acids on the survival and growth of plant. Pine and bush clover which are main natural species on the road side, and young radish and kidney bean which are cultivation species used in this test that responses of survival and growth were analyzed as grade concentration of deicers. Bush clover showed the most sensitive survival response among 4 species to the deicer. Pine growth didn't have statistical significance as the kind of deicers and concentration variation, but growths of bush clover and kidney bean showed growth inhibition in concentration more than 3% of $CaCl_2$ and EFD1. The results of survival and growth for $CaCl_2$(calcium chloride) demonstrated that young radish and pine are tolerant species and bush clover and kidney bean are sensitive species. Although EFD1 manufactured by chemical showed the negative effect on the survival and growth of plants, EFD2 made with waste compost was confirmed that it has the positive influence to the survival and growth of the both sensitive and tolerant plant species for chloride.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.21 no.8
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• pp.407-416
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• 2020

North Korea's demand for infrastructure construction and maintenance is growing rapidly. On the other hand, the number of skilled workers is insufficient. Therefore, through a survey of North Korean defectors, this study analyzed the status of construction technology and the difficulties of construction workers. In addition, an attempt was made to derive an appropriate education and training program process and operation plan. As a result of the survey, the reason for the low technical level of construction workers was the lack of skills, lack of motivation to work, and the lack of training and management systems. The appropriate education and training period was 56% of the total response within one year and 36% within six months. Based on the results of this survey, the period of education and training for the rapid training of construction technical personnel in North Korea was adopted as one year. Moreover, compared to the NCS standard in South Korea, appropriate training hours were suggested, excluding training courses, such as planning and design, construction management that require specialized knowledge. Finally, the curriculum corresponding to the education and training courses and the standards for facility names and required areas for facility operation were suggested.

• Journal of the Korea Academia-Industrial cooperation Society
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• v.18 no.5
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• pp.716-722
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• 2017

The present study numerically investigates the effect of obstacles located in the trajectory of fire plume flow on heat flow characteristics by using Fire Dynamics Simulation (FDS) software in an underground combined cycle power plant (CCPP). Fire size is taken as 10 MW and two different locations of fire source are selected depending on the presence of an obstacle. As the results, when the obstacle is in the trajectory of fire plume, hot plume arrives at the ceiling about 5 times slower in the upper of the fire in comparison to the results without obstacle. In addition, the average propagation time of ceiling jet increases by about 70 % with the distance from the ceiling in the upper of the fire, and it increases mainly about 4 times at the distance of 10 m. Consequently, it is noted that the analysis of heat flow characteristics in the underground CCPP considering fire scenarios is essential to develop the fire detection system for initial response on evacuation and disaster management.