• Journal of the Korea Institute of Information and Communication Engineering
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• v.17 no.3
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• pp.556-560
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• 2013

Recently, solutions to accommodate explosively growing mobile data traffic have attracted intensive attentions since the emergence of high-performance smartphones. Spectrum which can be exploited for mobile communications is very limited. Thus, femto cell is considered as an alternative because it can efficiently offload mobile data traffic from macro cells without using additional spectrum. In this paper, we mathematically analyzed the coverage of femto cell when it is deployed in an area where there exists signals from existing macro base stations. Our numerical results indicate that the coverage of femto cell increases as the total power of femto cell increases or the ratio of power allocated to pilot channel increases. However, it is also shown that the coverage of femto cell is very limited despite its high power when interference signals from macro base stations are strong.

• Korean Journal of Environment and Ecology
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• v.26 no.5
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• pp.801-811
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• 2012

The purpose of this study is to find out how land cover and planting of an urban park influence temperature. Field research on the land cover and planting status was conducted for Bundang Central Park in Sungnam-si. 30 study plots in the site were selected to closely analyze land cover type and planting structure. The temperature was measured 10 times for each plot. Land coverage type, planting type, planting layer structure and green space area (the ratio of green coverage, GVZ) were chosen as factors impacting temperature and statistics were analyzed for the actual temperature measured. Analysis on how the land coverage type influences temperature showed that planting site had a low temperature and that grassland and paved land had a high temperature. When it comes to planting type, the temperature at the land planted with conifers and broad-leaved trees was low, while the temperature at grassland and paved land was high. With regard to planting layer structure, canopy and canopy-underplanting type showed low temperature, while grassland and paved land showed high temperature. An analysis on the relation between green space area and temperature found out that both ratio of green coverage and GVZ had a high level of negative correlation with the temperature measured. According to regression model of green space area and the temperature measured, for every 1% increase in the ratio of green coverage, temperature is expected to lower by $0.002^{\circ}C$. Also, for every $1m^3/m^2$ increase in GVZ, temperature is expected to go down by $0.122^{\circ}C$.

• Nuclear Engineering and Technology
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• v.55 no.11
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• pp.3940-3955
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• 2023

A new method of numerical simulating prediction and decontamination effect evaluation for abrasive jet decontamination to radioactively contaminated metal is proposed. Based on the Computational Fluid Dynamics and Discrete Element Model (CFD-DEM) coupled simulation model, the motion patterns and distribution of abrasives can be predicted, and the decontamination effect can be evaluated by image processing and recognition technology. The impact of three key parameters (impact distance, inlet pressure, abrasive mass flow rate) on the decontamination effect is revealed. Moreover, here are experiments of reliability verification to decontamination effect and numerical simulation methods that has been conducted. The results show that: ⁶⁰Co and other homogeneous solid solution radioactive pollutants can be removed by abrasive jet, and the average removal rate of Co exceeds 80%. It is reliable for the proposed numerical simulation and evaluation method because of the well goodness of fit between predicted value and actual values: The predicted values and actual values of the abrasive distribution diameter are Ф57 and Ф55; the total coverage rate is 26.42% and 23.50%; the average impact velocity is 81.73 m/s and 78.00 m/s. Further analysis shows that the impact distance has a significant impact on the distribution of abrasive particles on the target surface, the coverage rate of the core area increases at first, and then decreases with the increase of the impact distance of the nozzle, which reach a maximum of 14.44% at 300 mm. It is recommended to set the impact distance around 300 mm, because at this time the core area coverage of the abrasive is the largest and the impact velocity is stable at the highest speed of 81.94 m/s. The impact of the nozzle inlet pressure on the decontamination effect mainly affects the impact kinetic energy of the abrasive and has little impact on the distribution. The greater the inlet pressure, the greater the impact kinetic energy, and the stronger the decontamination ability of the abrasive. But in return, the energy consumption is higher, too. For the decontamination of radioactively contaminated metals, it is recommended to set the inlet pressure of the nozzle at around 0.6 MPa. Because most of the Co elements can be removed under this pressure. Increasing the mass and flow of abrasives appropriately can enhance the decontamination effectiveness. The total mass of abrasives per unit decontamination area is suggested to be 50 g because the core area coverage rate of the abrasive is relatively large under this condition; and the nozzle wear extent is acceptable.

• Korean Journal of Environment and Ecology
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• v.25 no.2
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• pp.132-144
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• 2011

We studied the forest environment and characteristics of bird community between April and September of 2010 on the Hyangjeokbong area(A), Baekryunsa area(B) and Anseong area(C), all in the Deogyusan National Park. Hyangjeokbong area of the high latitude ridge was characterized by the Taxus cuspidata and Abies koreana etc., and deciduous broadleaf forest species, such as the Quercus mongolica, with abundance of subalpine zone coniferous trees, the Hemerocallis fulva and the Rhododendron schlippenbachii, while the areas Baekryunsa and Anseong were primarily characterized by deciduous broadleaf forests, with the valleys showing Fraxinus mandshurica colonies. In terms of the DBH(diameter at breast height) of trees, between 11 and 20cm showed the highest frequencies, while over 30cm was the highest in Baekryunsa area and the lowest in Hyangjeokbong area. Furthermore, in terms of coverage in relation to layers, in Hyangjeokbong area, the coverage volume of the lower layer was very high, in Baekryunsa area, the coverage volume of the middle layer between 8 and 12m was the highest, and in Anseong area, the coverage volume of the upper layer over 18m was the highest. A total of 53 bird species were observed during the study period at the Deogyusan National Park. The numbers of species and density of areas were 25 species and 45.20 Ind./km for Hyangjeokbong area, 50 species and 58.63 Ind./km for Baekryunsa area and 35 species and 66.89 Ind./km for Anseong area, with Baekryunsa area showing the highest number of species and Anseong area showing the highest level of density. In terms of dominant species, in Hyangjeokbong area, Cettia diphone, along with species which inhabit in grassland and shrubs, were the dominant species, and species which live in the canopy layer, including the Aegithalos caudatus, were found to be dominant in Baekryunsa and Anseong areas. For guild structure, bush nesting guild and bush foraging guild species were the highest in all areas, and the hole nesting guild and the air foraging guild species showed the lowest proportion. This seems to be the result of the low number of trees with diameter at breast height of over 30cm, which results in the lack of nesting grounds for hole nesting guild species.

• The Korean Journal of Ecology
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• v.17 no.2
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• pp.120-130
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• 1994

Stages of vegetation development on talus area were studied to examine temporal changes in species composition and vegetation structure, and to elucidate the mechanism of early patch formation. While ground coverage of lichens, which may form substrate for moss colonization and mitigate the heat-stress on rocks, decreased gradully, coverage of mosses increased slightly during primary succession. Ecological role of mossess related with water retention in community may be very important not only at pioneer stage but also at later stages because of little soil development on this talus area. Species diversity and species richness increased during the early stages of succession. Parthenocis년 tricuspidata and Sorbaria sorbifolia var. stellipa dominated in liana stage, Ulmus davidiana for. suberosa and Lindera obtusiloba in shrub stage, and Fraxinus rhynchophylla and Actinidia arguta in subtree stage, however, was composed of mixed forest of several tree species. U. davidiana for. suberosa, L. obtusiloba, Securinega suffruticosa and Rhus chinensis were relatively important woody species in early patch forming process. The results, however, suggested that early establishment on talus area might be strongly associated with chance for safe-site because both pioneer species and later species could take part in early patch forming process.

• Asian Journal of Turfgrass Science
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• v.16 no.1
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• pp.41-47
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• 2002

For this study grasp quantitative humidity variation with planting stratification to various green space of calculation method, observed humidity distribution in the green space. with this data, coverage condition and humidity distribution, planting calculation method and humidity, planting stratification calculation method and humidity, analyzed by revolution analysis. In this result, as well as coverage condition, planting stratification effect humidity variation. increasing planting ratio (area) and planting volume (capacity) effect higher humidity. especially, if we compared between planting stratification calculation method and higher humidity, effect by a revolution coefficient and a correlation coefficient, effect relatively planting volume (capacity) higher than stratification ratio (area). today, in the index of higher humidity, planting calculation propose application of capacity method.

• Archives of Reconstructive Microsurgery
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• v.25 no.1
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• pp.15-18
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• 2016

Any types of burn injury that involve more than deep dermis often require reconstructive treatment. In gluteal region, V-Y fasciocutaneous advancement flap is frequently used to cover the defect. However, in case of large burn wounds, this kind of flap cannot provide adequate coverage because of the lack of normal surrounding tissues. We suggest V-Y adipofascial flap using the surrounding superficially damaged tissue. We present the case of a patient who was referred for full-thickness burn on gluteal region. We performed serial debridement and applied vacuum-assisted closure device to defective area as wound preparation for coverage. When healthy granulation tissue grew adequately, we covered the defect with surrounding V-Y adipofascial flap and the raw surface of the flap was then covered with split-thickness skin graft. We think the use of subcutaneous fat as an adipofascial flap to cover the deeper defect adjacent to the flap is an excellent alternative especially in huge defect with uneven depth varying from subcutaneous fat to bone exposure in terms of minimal donor site morbidity and reliability of the flap. Even if the flap was not intact, it was reuse of the adjacent tissue of the injured area, so it is relatively safe and applicable.

• The Journal of the Korean dental association
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• v.58 no.1
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• pp.8-18
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• 2019

This case report presents results for gingival recession coverage following gingival grafting and for gingival biotype enhancements by visualizing soft tissue volume changes using intraoral three-dimensional scanning. A 28 year old female patient with multiple gingival recessions and a 19 year old female patient with a single gingival recession on mandibular anterior area were treated. Root coverage was performed in both cases using autogenous subepithelial connective tissue harvested from palate. Intraoral 3D scan data were obatained presurgery and at 3 months, 1 year, and 2 years postsurgery. The recession areas were recovered successfully by subepithelial connective tissue graft combined with pedicle flap repositioning, and the patients showed neither further recurrence nor post-operative complication. Soft tissue biotype changes were identified by superimposing and analyzing scan data, revealing that gingival biotype was enhanced in both cases. These cases suggest that SCTG could be advantageous in terms of the gingival biotype enhancement, as well as gingival recession coverage, and intraoral 3D scanning might be suitable for assessing post-surgical gingival biotype change.

• Proceedings of the Korean Institute of Information and Commucation Sciences Conference
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• 2017.05a
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• pp.738-740
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• 2017

Visible light communication is a communication method using light, and it has advantage of ensuring security in a single space as compared with RF communication. However, in the area outside the visible line of the light, communication disconnection occurs. Therefore, this paper proposes a relay module to overcome the coverage extension and communication disconnection phenomenon of visible light communication. The proposed relay module transmits and receives data of visible light communication by sequentially transmitting data packets including target ID through adjacent visible light module. Through experimentation of data transmission, we confirmed the extension of the transmission range and the data reception in the area outside the line of sight.

• The Journal of Korean Institute of Communications and Information Sciences
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• v.30 no.4B
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• pp.170-177
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• 2005

Due to the redundant rebroadcast packets, network-wide broadcasting is a costly operation in wireless mobile ad hoc networks. To reduce this redundancy, most of previous approaches implicitly or explicitly require periodic refreshing of neighborhood information which continuously imposes additional broadcast overheads. In this paper, we propose a practical broadcast pruning scheme based on the local prediction of a remained coverage area. As the proposed scheme uses only information available in the on-going broadcast process, it can minimize the overheads prevalent in previous approaches.