• Journal of the Korea Academia-Industrial cooperation Society
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• v.14 no.11
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• pp.5879-5884
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• 2013

With the rapid industrialization and economical development, the electricity demands of the industrial facilities and densely populated large cities are continuing to increase in Korea. The increase in the power consumption requires the extension of power facilities, but it is difficult to secure spaces for equipment installation in the limited space of urban areas. In addition, the 154 kV or 345 kV transmission systems in Korea has a short transmission distance, and are connected to one another in network structures that ensure the high reliability and stability of power supply. This structure reduces the impedance during the fault in power system, and increases the magnitude of in the short circuit fault current. The superconducting fault current limiter (SFCL) was devised to effectively address these existing problems. The SFCL is a new-concept eco-friendly protective device that ensures fast operation and recovery time for the fault current and does not need additional fault detection devices. Therefore, many studies are being conducted around the world. In this paper, based on the wiring method the initial fault current characteristics, current limiting characteristics, according to the incident angle and the change in inductance current limiting characteristics were analyzed in a multifaceted methods.

• International Journal of Highway Engineering
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• v.14 no.2
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• pp.131-143
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• 2012

The past researches on roadway segment safety estimation focused on intersections, which are the primary traffic accident regions. The past researches on roadway segments, However, analyzed the effects of certain factors on the traffic accident occurrence rate by organizing the individual geometric structures of the roads, and there is still a dearth of researches on the development of a traffic accident estimation model for rural roadway segments. Therefore, this research focused on rural two-lane and multilane roadway segments and developed traffic accident estimation models through the application of statistical techniques. This is required to explain such high frequency of zero counts in the traffic accident data. In this research, it was found that the Hurdle model is more suitable than the Poisson or negative binomial-regression model for explaining the excess zeros case. In addition, main variables were chosen to estimate their effects on traffic accident occurrence at rural roadway segments, and the safety at such rural roadway segments was estimated. In this research, it was assumed that there are different factors that affect the safety at two-way lane and multilane roadway segments, and a traffic accident estimation model was developed by dividing the two-way lane and multilane roadway segments.

• Land and Housing Review
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• v.2 no.2
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• pp.195-204
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• 2011

During mechanical demolition of RC structures, weights of dismantling equipment and demolition waste of building are applied to unexpected load which did not be considered during the design of structural member. Nevertheless, the loading of dismantling equipment and dismantling process are mainly dependent on field managers' field workers' or experiences without considering safety of structural member by a structural engineer. It is urgently required that reflecting actual circumstance of mechanical demolition, safety evaluation method to evaluate the safety and the guideline for appropriate capacity of structural member to support dismantling equipment weight, be provided. Through site investigation and questionnaire on field workers, this paper proposed demolition waste load, load factor, strength reduction factor, and so on. These are essential to safe evaluation of a building, ready to demolition. Considering actual circumstance of mechanical demolition, safety evaluation method of building and design method of slab and beam was suggested to a dilapidated building. An capability to loading of dismantling equipment was proposed, applied to RC slab and RC beam. Therefore, the suggested safety evaluation method and the guideline for an capability to loading of dismantling equipment weight can reasonably evaluate the capacity of structural member in demolition and use effectively as increasing efficiency and improving safety of demolition through proper management of dismantling equipments.

• Journal of the Korean Society of Surveying, Geodesy, Photogrammetry and Cartography
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• v.36 no.2
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• pp.105-112
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• 2018

To determine the position of receiver, the GPS (Global Positioning System) uses position information of satellites and pseudo ranges based on signals. These are reflected by surrounding structures and multipath errors occur. This paper proposes a method for multipath error reduction using digital images to enhance the accuracy. The goal of the study is to calculate the shielding environment of receiver using image processing and apply it to GPS positioning. The proposed method, firstly, performs a preprocessing to reduce the effect of noise on images. Next, it uses hough transform to detect the outline of building roofs and determines mask angles and permissible azimuth range. Then, it classifies the satellites according to the condition using the image processing results. Finally, base on point positioning, it computes the receiver position by applying a weight model that assigns different weights to the classified satellites. We confirmed that the RMSE (Root Mean Square Error) was reduced by 2.29m in the horizontal direction and by 15.62m in the vertical direction. This paper showed the potential for the hybrid of GPS positioning and image processing technology.

• Economic and Environmental Geology
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• v.42 no.4
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• pp.343-356
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• 2009

SCS method was applied to make the assessments of direct runoff according to land use changes in Jeju island. Land uses were obtained from 5 year-period remote sensing time series data from 1975 to 2000 which are provided by Water Management Information System (WAMIS). Hydrologic soil groups were categorized based on soil series of National Academy of Agricultural Sciences (NAAS), and permeable geologic structures such as Sumgol, Gotzawal and so on. The land uses of Jeju island are obviously characterized by urban-agricultural areas increases, and forest areas decrease. According to land use changes, curve number (CN) for Jeju island was consistently increased from 65.3 in 1975 to 69.6 in 2000. From 1975 to 2000, the amount of direct runoff and ratios increased due to CN changes. When the rainfall data in 1995 was applied to each year, the direct runoff amounts were $299.0{\sim}351.6\;mm$, and runoff ratios were $15.1{\sim}17.7%$. In the case of the application of the rainfall data in 2000, the direct runoff amounts were $136.9{\sim}161.5\;mm$, and runoff ratios were $9.7{\sim}11.5%$. Since direct runoff can be closely related to groundwater recharge and sustainable groundwater yield, the groundwater influence caused by land use changes or district exploitations should be considered for the reasonable water management and development in Jeju island.

• Ecology and Resilient Infrastructure
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• v.6 no.4
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• pp.191-199
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• 2019

Road development is considered an important factor in invasion and dispersion of ailen plants by damaging the natural ecosystems and connecting the detached landscapes into long tubular structures. In this study, vegetation survey was carried out according to the topographical characteristics of cut slope, fill slope, and flat land at the construction site in order to understand the effect of road developemt on the change of the floristic composition of ailen plants. Road developement projects caused a lot of changes in annual and biennial alien plants because of continuous disturbances. Changes in species composition of alien plants decreased in the cut slope. On the other hand, the ailen palnts of the fill slope increased. The increase or decrease alien plants on flat land were identified depending on where it occurred, and no major trend was found. The cause of these change was driven by unintentionally introduced alien plants. In particular, the cut slope with a high occurence of unintentional ailen plants should not be used as a source of high-risk alien plants such as ecosystem disturbances. Since the transplanted species were intentionally planted by the landscape plan, it was possible to identify colonies from early stages and spread to the nearby flat land. Therefore, in order to minimize the impact of road slope vegetation on the surrounding ecosystem during and after road construction, it is suggested to plant high viability plants in the landscape design during the environmental impact assessment consultation.

• Korean Journal of Fisheries and Aquatic Sciences
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• v.16 no.3
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• pp.273-290
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• 1983

A bionomic study of the coralligenous concretionary hard bottom in the northwestern Mediterranean was carried out at four stations : three stations(Arnette, Laurons, Auguette) under the influence of intense multisource pollution(gradient decreasing from north to south) in the Gulf of Fos, west of Marseille, France, and one control station(Moyade islet) in an unpolluted area near Riou island, east of Marseille. Along the increasing pollution gradient from the outer to the inner part of the Gulf of Fos, there is a qualitative and quantitative impoverishment of the fauna. On the whole, the species richness, the numerical abundance. and the species diversity index are all on the decrease. Accordingly, the innermost station in the Gulf of Fos(Auguette) is most heavily affected by the industrial, and to a lesser extent by the domestic wastes, from the nearby industrial complex and urban areas. The impact on the benthic coralligenous community of this serious alteration has been analysed in view of community composition, functional aspect, and ecological stocks. The faunal affinity between stations has been studied by means of the two coefficients : fourfold point correlation coefficient and Jaccard's community coefficient. The upper layer and inferior face communities of the coralligenous concretionary structures are also compared.

• Journal of the Korean Geographical Society
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• v.44 no.4
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• pp.481-496
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• 2009

Every coastal area exhibits its own unique landscape owing to the combination of the natural and cultural processes. Coastal barrier islands well show the cultural aspects of American coastal landscapes. Some 47% of barrier island area was occupied by urban and built-up area in New Jersey, while some 5% in Georgia. Tourism-related development is back to in the mid 19C. in N.J. due to the closeness to heavily populated areas such as New York and Philadelphia. Developments without proper understanding the nature of coastal processes caused New Jerseyization, the destruction of the beauty or naturalness. It was mainly due to the lack of growth-control policies and the foresight for the future coast in the processes of legislation. North Carolina's islands experienced an increase of 269% in urbanized acreage between 1956 and 1976. However, N.C. exercised her wisdom to recover the naturalness of the coastal environs: all engineering structures are banned on the beaches. Nine out of 13 barrier islands in Georgia exist in the wilderness condition owing to her unique history. The remaining islands still experienced the least development. After the Civil War most of Georgian islands were owned by rich families and maintained as wilderness. In the 1970s most of the uninhabited islands were sold or donated to research institutes or governmental agencies.

• Journal of the Korean Geotechnical Society
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• v.20 no.2
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• pp.87-96
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• 2004

Application of the soil nailing method is continuously extending in maintaining stable excavations and slopes. However, ground anchor support system occasionally may not be used because of space limitations in urban excavation sites nearby the existing structures. In this case, soil nailing system with relatively short length of nails could be efficiently adopted as an alternative method. The general soil nailing support system, however, may result in excessive deformations particularly in an excavation zone of the existing weak subsoils. Pretensioning the soil nails then could play important roles to reduce deformations mainly in an upper part of the nailed-soil excavation system as well as to improve local stability. In this study, a newly modified soil nailing technology named as the PSN (Pretension Soil Nailing) is developed to reduce both facing displacements and ground surface settlements in top-down excavation process as well as to increase the global stability. Up to now, the PSN system has been investigated mainly focusing on an establishment of the design procedure. In the present study, laboratory model tests are carried out to investigate the failure mechanism and behavior characteristics of the PSN system. Various results of model tests are also analyzed to provide a fundamental basis for the efficient design.

• Land and Housing Review
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• v.3 no.3
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• pp.299-305
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• 2012

Various types of bio wood chip for fermentation-extinction of food waste was investigated by comparing their different pore structure with the performance of weight loss rate and microbial activity. The fermentation-extinction of food waste with bio wood chip was examined by adding 700~1,500g of food waste every day during 15 days to the fermentation-extinction reactor with condition of $30{\sim}50^{\circ}C$ temperature and 30~70% humidity, where 1,500g of bio wood chips were existed. The bio wood chips used in this experiment were categorized into 4 different types; microbial-mixing type(A biochip), macro pore type(B biochip) under $2{\mu}m$ of pore size, micro pore type of wood-chips(C biochip) under $0.1{\mu}m$ of pore size, viscous & sticky type(D biochip). As a result, A, B, C, D bio wood chip exhibited 85%, 63%, 92%, 73% weight loss of food waste with fermentation-extinction. The maximum weight loss of food waste was obtained at the fermentation-extinction experiments by using C bio wood chip. On the other hands, the maximum ratio of ATP to COD and TN was obtained from $3.00{\times}10^{-10}$ and $2.31{\times}10^{-11}$ in the case of C bio wood chip, comparing with other types of bio wood chip. Consequently, the performance of weight loss rate was affected with the micro pore structure of bio wood chip which have an advantage of extensive microbial activity space in the fermentation-extinction of food waste.