• Archives of Craniofacial Surgery
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• v.17 no.3
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• pp.135-139
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• 2016

Background: The ultimate goal of craniofacial reconstructive surgery is to achieve the most complete restoration of facial functions. A bioabsorbable fixation system which does not need secondary operation for implant removal has been developed in the last decade. The purpose of this study is to share the experience of authors and to demonstrate the efficacy of bioabsorbable mesh in a variety of craniofacial trauma operations. Methods: Between October 2008 and February 2015, bioabsorbable meshes were used to reconstruct various types of craniofacial bone fractures in 611 patients. Any displaced bone fragments were detached from the fracture site and fixed to the mesh. The resulting bone-mesh complex was designed and molded into an appropriate shape by the immersion in warm saline. The mesh was molded once again under simultaneous warm saline irrigation and suction. Results: In all patients, contour deformities were restored completely, and bone segments were fixed properly. The authors found that the bioabsorbable mesh provided rigid fixation without any evidence of integrity loss on postoperative computed tomography scans. Conclusion: Because bioabsorbable meshes are more flexible than bioabsorbable plates, they can be molded and could easily reconstruct the facial bone in three dimensions. Additionally, it is easy to attach bone fragments to the mesh. Bioabsorbable mesh and screws is effective and can be easily applied for fixation in various craniofacial trauma reconstructive scenarios.

• Journal of Korean Foot and Ankle Society
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• v.15 no.2
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• pp.51-57
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• 2011

Pilon fractures involving distal tibia remain one of the most difficult therapeutic challenges that confront the orthopedic surgeons because of associated soft tissue injury is common. To introduce and describe the diagnosis, current treatment, results and complications of the pilon fractures. In initial assessment, the correct evaluation of the fracture type through radiographic checkup and examination of the soft tissue envelope is needed to decide appropriate treatment planning of pilon fractures. Even though Ruedi and Allgower reported 74% good and excellent results with primary open reduction and internal fixation, recently the second staged treatment of pilon fractures is preferred to orthopedic traumatologist because of the soft tissue problem is common after primary open reduction and internal fixation. The components of the first stage are focused primarily on stabilization of the soft tissue envelope. If fibula is fractured, fibular open reduction and internal fixation is integral part of initial management for reducing the majority of tibial deformities. Ankle-spanning temporary external fixator is used to restore limb alignment and displaced intraarticular fragments through ligamentotaxis and distraction. And the second stage, definitive open reduction and internal fixation of the tibial component, is undertaken when the soft tissue injury has resolved and no infection sign is seen on pin site of external fixator. The goals of definitive internal fixation should include absolute stability and interfragmentary compression of reduced articular segments, stable fixation of the articular segment to the tibial diaphysis, and restoration of coronal, transverse, and sagittal plane alignments. The location, rigidity, and kinds of the implants are based on each individual fractures. The conventional plate fixation has more advantages in anatomical reduction of intraarticular fractures than locking compression plate. But it has more complications as infection, delayed union and nonunion. The locking compression plate fixation provides greater stability and lesser wound problem than conventional implants. But the locking compression plate remains poorly defined for intraarticular fractures of the distal tibia. Active, active assisted, passive range of motion of the ankle is recommended when postoperative rehabilitation is started. Splinting with the foot in neutral is continued until suture is removed at the 2~3 weeks and weight bearing is delayed for approximately 12 weeks. The recognition of the soft tissue injury has evolved as a critical component of the management of pilon fractures. At this point, the second staged treatment of pilon fractures is good treatment option because of it is designed to promote recovery of the soft tissue envelope in first stage operation and get a good result in definitive reduction and stabilization of the articular surface and axial alignment in second stage operation.

• Journal of Korea Water Resources Association
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• v.49 no.8
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• pp.693-705
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• 2016

In this study, the effects of sediment supply on the downstream of a large dam are investigated using a numerical model. The model simulation shows a good agreement with laboratory experiment results of sediment transport and diffusion from sediment pulses. The water surface changes from the various sediment bed elevations are also simulated using the model. The site which has a relatively stiff bed slope and meandering of a channel is selected as an appropriate location for sediment supply because of its shear stress enough to supply the sediment downstream. The model simulation shows the decrease of channel bed elevation through the simulation period with time. The well-deposition of sediment supplied from the downstream of dam is found in the location where the flow rate is relatively low. A bed relief index is increased with time and it is relatively greater in downstream compared to upstream. The channel bed variability increases as flow rate increases with a greater bed relief index. The results of this study demonstrate the importance of increasing water discharge of a large dam to increase the dynamic of channel bed and thus to enhance the efficiency of channel bed restoration by sediment supply.

• Ecology and Resilient Infrastructure
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• v.2 no.1
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• pp.22-32
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• 2015

This study investigated the difference in fish community structures in a main channel and an isolated former channel, considering the environmental factors in the Mangyeong River, Korea. Principal component analysis (PCA) with environmental factors showed that former channels were composed of a fine substrate covered by in-stream vegetation, whereas the main channel was covered by a wide range of substrates with a higher dissolved oxygen and conductivity. The result of the hierarchical cluster analysis with species abundance delineated to the four main groups; three abandoned channel groups and one main channel group. Non-metric multidimensional scaling (NMDS) showed that fish community structures of each study site differed from environmental factors: former channel fish communities were positively related to in-stream vegetation cover, whereas main channel fish communities were positively associated with dissolved oxygen and conductivity. The results indicated that channelization, where there was a separation between the former channel and the main channel, had detrimental effects on fish community structures of both the main channel and the abandoned channel in the Mangyeong River. In conclusion, this study suggested that the connectivity between the main channel and abandoned channel were required to enhance both habitat structural diversity and species diversity of the Mangyeong River.

• Ecology and Resilient Infrastructure
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• v.1 no.1
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• pp.39-48
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• 2014

In order to establish fundamental data for stream restoration and environmental flow, we investigated optimal ecological flowrate (OEF) and riverine health condition in the Chogang Stream, a tributary to Geum River, Korea. The number of fish individuals sampled in this period were 4,669 in 36 species of 9 families. The most abundant species was Korean chub (Zacco koreanus, 34.0%) followed by pale chub (Z. platypus, 22.6%) and Korean shinner (Coreoleuciscus splendidus, 13.3%). Index of biological integrity (IBI) and qualitative habitat evaluation index (QHEI) values decreased from upstream to downstream along the stream. The estimated IBI value ranged from 27.9 to 38.6 with average 32.2 out of 50, rendering the site ecologically fair to good health conditions. OEF was estimated by the physical habitat simulation system (PHABSIM) using the habitat suitability indexes (HSI) of three fish species Z. koreanus, C. splendidus and Pseudopungtungia nigra selected as indicator species. In Z. koreanus, HSI for flow velocity and water depth were estimated at 0.1 to 0.4 m/s and 0.2 to 0.4 m, respectively. In P. nigra, HSI for flow velocity, water depth and substrate size were estimated at 0.2 to 0.5 m/s and 0.4 to 0.6 m and fine gravel to cobbles, respectively. OEF values increasing from up to downstream was found to increase, weighted usable area (WUA) values increased accordingly.

• Korean Journal of Ecology and Environment
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• v.46 no.1
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• pp.18-24
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• 2013

The objective of study was to protect seabird breeding site and vegetation restoration of Chilbal and Sokugul island in Shinan county Jeonnam province, April and December 2011. We analyzed the soil properties according to the dominant communities and environmental gradient. As a result, It was highly analyzed to moisture content, organic matter, salinity, total nitrogen in Commelina communis community and low analyzed in Achyranthes japonica community. Carex boottiana community which mainly used as a seabird habitat has a wide range and Achyranthes japonica and Artemisia princeps community was narrowed to soil properties. Soil pH of Carex boottiana community in Sogugul island was the lowest on 3.14 and Peucedanum japonicum community was the highest. Soil moisture content and organic matter was analyzed by the high value in Peucedanum japonicum community. In contrast, Achyranthes japonica was the low value and Carex boottiana community was analyzed the highest on the salinity and total nitrogen. On the soil environmental characteristics according to the environmental gradient, The higher altitude, moisture content, organic matter, salinity and total nitrogen was the lower in Chilbal island. In the case of Sokugul island, the altitude difference did not show the characteristics of soil environmental factors for small area and low altitude. But moisture content is similar to soil property of Chilbal island. Soil property was strongly acid soil because of seabird dropping. This results will be helpful to manage the invasive plants.

• Journal of the Korea institute for structural maintenance and inspection
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• v.22 no.1
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• pp.6-12
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• 2018

Recently, The use of the curtain wall method is increasing in construction. The curtain wall construction is widely applied to the exterior wall of the building for shortening construction period and economical efficiency. However, the replacement of deterioration of the weather resistance and structural behavior of the sealing material connecting the curtain wall method and the glass frame is necessary for introduction of the stable curtain wall method and quality improvement in accordance with KS F 4910 standard. In this study, the elastic restoring force test was performed in the external environment. In this study, the deterioration of the sealant was evaluated for structural sealants. In Korea, studies on the variable displacement behavior of structural sealants are lacked. In this study, the reproduced results in laboratory conditions are compared with the deteriorating conditions exposed to the external environment, and they are reflected in the design of sealing materials in the future. According to the results of the study, it was confirmed that the existing structure sealant meets the quality standard of KS F 4910, but in the conditions performed in this study, adhesion failure of the specimen and cracking of the surface occurred. Especially, in the weather resistance test, it is necessary to evaluate the long-term durability performance of the structural sealant used in the curtain wall method by checking the insoluble state of all the test pieces. Therefore, in order to apply a conventional structural sealant to the site, it is necessary to introduce another durability performance evaluation.

• Korean Journal of Environmental Biology
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• v.17 no.3
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• pp.337-344
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• 1999

This study was carried out to investigate the influence of spa sewage on water quality and chemical contents in the paddy soil along stream from 1997 to 1998. Concentration of $PO_4, SO_4, Cl, NH_{4}, Ca, Na$ and COD in the spa sewage were lower than standard for agricultural usage, and were lowered as the sewage flew to the into stream. The concentration of $SO_4$in spa sewage was over the criteria for agricultural usage in the inlet, but was lower than criteria for agricultural usage by inlet of non polluted stream water. Concentration of pollutants in the sediment of water channel were the highest in the inlet site. There were no pollutants accumulation in the paddy soil where spa sewage was irrigated. It may be resulted from nutrients uptake of rice plant and self purification of paddy soil. On the while, considering electric conductivity and nitrate in spa sewage, this results suggest that long-term irrigation of the spa sewage may be required general management with some decreasing fertilization.

• Korean Journal of Environment and Ecology
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• v.22 no.1
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• pp.35-42
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• 2008

This study was conducted to provide basic information that can be used to restore habitats of Nannophya pygmaea. Nannophya pygmaea is an endangered species of wildlife fauna in Korea and its habitats are distributed very scarcely in Korea. Ten wetland sites throughout Korea, where N. pygmaea inhabited (2 sites in Incheon Muui-do, 1 site in Gokseong Singi-ri, 4 sites in Gokseong Wolbong-ri, and 3 sites in Mungyeong Yulsu-ri) were investigated from June 2006 to August 2007. Investigation was made on landscape properties, habitat sizes, vegetation types, water environments, and water sources. N. pygmaea was generally found in the abandoned paddy fields surrounded by mountains. The habitats ranged from $113.4m^2$ to $1,153.1m^2$ in area, and were mostly dominated by Juncus effusus and Persicaria thunbergii. The water level was $2.6\sim7.3cm$, and the water temperature ranged from $16^{\circ}C$ to $27.8^{\circ}C$. The elevation of the habitats ranged from 139 to 243 m above sea level, which was mostly lower than that of other high mountain wetland habitats. In conclusion, the habitats of N. pygmaea can be restored at wetlands, which have similar condition with field habitat such as abandoned paddy fields in the beginning stage of oligotrophy. Because N. pygmaea is sensitive to microtopography and other surrounding environments, the approach to restore the habitats for N. pygmaea should consider those microhabitat conditions shown in this study.

• Journal of the Korean Geotechnical Society
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• v.21 no.5
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• pp.93-101
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• 2005

The formation of slopes is unavoidable under the special circumstance of Korea where $7%$ of the whole area are composed of mountains and civil engineering projects such as road and site developments are increasing with industrial development and horizontal expansions of urban area. Stability of slopes is one of quite important issues under special meteorological characteristics that over two-thirds of annual average rainfall is concentrated in summer season and the localized torrential downpour is getting more frequent recently. As a result of these circumstances, partial slope failures by debris flow of the high water content soils occur frequently in cut soil slopes. In this case of debris flow slope failure, slope declination method is selected fur the stable recovery because it is impossible to recover entirely by existing recovery methods. Seeding or special grass planting methods are followed separately without exception. The method by which entire recover with bigger stability ratio would be possible and grass planting work would be done simultaneously is developed. For debris flow failure slopes, this study secured the safety of slopes by preventing the inflow of rainwater and scour using geosynthetics-reinforced embankment, and created nature-friendly slopes by planting trees on the slopes.