• Proceedings of the Korea Concrete Institute Conference
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• 2000.10a
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• pp.705-710
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• 2000

Recently, use of sea-sand as fine aggregates in reinforced concrete structures is increasing because of lacking of supply due to destructive of environment caused by obtaining and exhausting of resource. It rise up issue, some field reconstruction, interrupted construction works occurring to the trouble on the site because sometimes engineer does not agree to use of corroded bar, even slighly corroded. This study investigates the properties of bond strength and the structural behavior of corroded bars before and after placement. The purpose of the study is to present the database estimating degree of damaged bond strength according to corrosion level and deciding on whether using corroded bars or not.

• Proceedings of the Korean Association of Geographic Inforamtion Studies Conference
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• 2010.06a
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• pp.277-278
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• 2010

본 연구는 황해 아산만 중앙천퇴(Surface Sediment)에서 최근 대규모 방조제 건설과 연안 준설로 인해 야기된 해저지형변화에 대한 연구이다. 이러한 해저지형변화는 해도상의 수심정보를 왜곡시킴으로써 국제항을 출입하는 대형선박의 안전항해에 위험요소로 작용할 수 있어, 안전한 항해수로 확보 및 해양사고 저감 대책 마련이 시급하다. 이러한 맥락에서 근본적인 중앙천퇴 지형변화의 원인, 해저지형변화의 양상을 파악하는 것이 이 연구의 일차적인 목적이다. 더 나아가 장 단기 해저지형변화 예측을 통해, 궁극적으로 항해 위험요소 저감 대책 및 정책 마련 시 과학적인 핵심기반기술을 제공하는 것이다. 결국 GIS 기반의 해저지형 공간 분석을 토대로 기존의 미시적인 데이터에 의거한 퇴적환경 연구결과를 객관화하고 정량적인 근거를 제시하는 도구로 활용할 것이다.

• Proceedings of the Korea Water Resources Association Conference
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• 2004.05b
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• pp.992-996
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• 2004

천해역(shallow sea area)에서의 조류 형태(tidal flow regime)는 주로 만(bay)이나 해안선(shoreline)의 형태, 해저 지형(bottom topography), 수로(channel), 천퇴(sand bar)나 간석지(tidal flat) 등의 지형적인 요인에 의해 결정된다. 본 연구는 복잡한 지형적 변화 및 천해특성에 기인된 조석(tide)의 현상이 뚜렷이 나타나는 금강하구(Keum River Estuary)를 하구둑(Estuary Dike) 건설 전${\cdot}$후(Before and After Constructed)의 수심(depth)변화 및 유속(current)변화를 수치실험(numerical experiments)으로 고찰했다.

• Proceedings of the Korea Concrete Institute Conference
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• 1996.10a
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• pp.127-132
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• 1996

Recently in the country a corrosion of steel is accelerated due to using of sea sand including salts, and critical problem on the durability of concrete structure is occured. Thus a control of steel corrosion is very important in the stability of structure. Coated steel is in use with a method of steps of steel corrosion in U.S,A. Japan etc, and as well in domestic case the manufactured coating steel of three types is on the market. Those are Epoxy coated steel, Zinc-strength, concrete specimen size, bar diameter, which can affect bond characteristics between steel and concrete in order to know their relative bond characteristics.

• KIEAE Journal
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• v.10 no.5
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• pp.123-129
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• 2010

This study aimed at analyzing the trend of carbon dioxide emission for direct and indirect areas by using inter industry relations table between 2000, 2003 and 2005 in the key building materials and components. Results of this study are as follows; First, the material and components for this study was selected in 20 industries of products such as sand, gravel, cement, concrete articles, rebar, and steel bar. Second, among the 20 selected key building materials, the group with the highest carbon-dioxide emission was shown in ready-mixed concrete, concrete articles, and primary aluminum goods. Third, as a result of analyzing the changes to the units of carbon dioxide emission according to passage of time, the number of items which is changed in such as sustained increase or decrease over time was insignificant in carbon-emission change trend.

• Proceedings of the Korea Committee for Ocean Resources and Engineering Conference
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• 2003.05a
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• pp.157-162
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• 2003

Nakdong estuary is located at south-eastern coast of the Korea. A lot of sediment from upper river were deposited at this area. It has cause many problem such as changes in topography and tidal current. Changes of characteristic of deposition were cause by topographic change of nakdong estuary. Analyzing and evaluating data, we could predict the direction of movement of the sand bar and the growth toward south-eastern of Nakdong estuary. It was caused by decreasing river discharge after construction of Nakdong-kang barrage.

• Ecology and Resilient Infrastructure
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• v.4 no.1
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• pp.44-53
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• 2017

In order to investigate the response in fauna and biological communities of terrestrial insects to the vegetation encroachment on the sandbar, species composition, species diversity, functional species traits and community structure of land-dwelling insects sampled by a pit-fall trap were compared at the bare and vegetated sandbar of a typical sand-bed stream, the Naeseong Stream, Korea. Species diversity of the insects was increased but their density was decreased as the riparian vegetation encroached at the sandbar. In particular, indicator species of bare sandbar such as Cicindela laetescripta and Dianemobius csikii, were found at the bar sandbar. The insect communities were clearly classified at the bare and vegetated sandbar according to coverages of riparian plants. The food web of the bare sandbar was composed of detritus - detritivore and scavenger - predator consisted mainly of Coleoptera. On the other hand, the food web of the vegetated sandbar was composed of plants - sucking and chewing herbivore - parasitoid and predator. These results showed that biodiversity of terrestrial insects was increased, food web was changed from grazing to detritus food chain, and insect fauna specific bare sandbar disappeared as the riparian vegetation invaded on the sandbar of a sand-bed stream.

• Journal of the Korean Society of Environmental Restoration Technology
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• v.6 no.4
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• pp.62-73
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• 2003

The study was to apply a mat style reed planting method at confluence to improve plants growth conditions by relaxing disturbed topographical base due to water flow and was intended to review the effect to build up a vegetation strip by monitoring process after the construction. First off, We've attempted to construct reed mats on selected sites as confluences of Tan and Gaehwa stream and then examined and analyzed characteristics of soil and vegetation community. As the results of the examination, the soil texture was proven to be a mix of sand and loamy sand and be 6.3 ~ 7.0 soil pH. In addition, it contained 1.0 ~ 4.6% of organic matter, 0.04 ~ 0.22% of T-N and 27.8 ~ 41.2% of water content. For its vegetation structure, the Tan stream confluence was first actually a point bar without plants prior to the construction but 8 kinds of hygrophytes including Persicaria hydropiper and 9 kinds of terrestrial plants such as Potentilla supina, Artemisia annua, and Alopecurus aequalis var. amurensis. On the other hand, the Gaehwa stream confluence contained 6 kinds of hygrophytes such as Bidens frondosa and other 11 kinds of terrestrial plants prior to the construction while it produced 7 kinds of hygrophytes including Ranunculus ternatus as well as Phragmites australis and 9 kinds of terrestrial plants such as Potentilla supina after the construction. For the Phragmites australis, almost of them was weathered away in early days just after planting because of development period passed, but on May, six months later from planting, it was investigated that its length was approximated as 65 ~ 85cm with 75% coverage and that the number of it was 437 ~ 633/$m^2$. The study was shown that reed mats can improve environmental conditions of disturbed topographical base, enabling natural growth of various riparian vegetation including the introduced plant, reed. In the meantime, it was supposedly judged that to recover or build up a vegetarian strip, supplementary materials should be prepared to help produce and grow plants because it is not probable to expect river drift by water flow at confluence and that corrosion, burying or inundation owing to changes of water lever should be considered.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.17 no.2
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• pp.61-69
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• 2005

The coastal erosion and the look of a heap which are mainly occurred in the district along the coast are found for various forms such as the estuary closing, the estuary sand bar the development of the coast sand bar, and the modification of coastline. Recently, due to the coastal development, these transformations have been intensified. The change of coast, which has been made slow progress is required long-term study on a searching examination of the root cause and a suggestion of a counter measure. In this research, ortho aerial photos were produced to analyze volumes of topographical alternations that have been progressed fer the long run, by 10s cycle from 1940s through 1990s, to compute accurate volumes of coastline variation, through a datum point and G.C.P (Ground Control Point). Also in this study, without respect to water level, the coastline variation was analyzed by using comparatively analyzed a Idlest land map, a cadastral map. And to analyze topographical variation volumes, the tidal station's materials was used under consideration f3r tide. Finally, topographical variation volumes are comparatively analyzed through surveying and sounding and a point of fine of aviation photographing was calculated and revised. After this research, by using ortho aerial photos, We can understand efficiency of these in computing volumes of variations of coastline by analyzing quantitatively erosion and look of a heap. Besides, in the future, these will be used for information gathering of the coastline integration control system.

• Ecology and Resilient Infrastructure
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• v.3 no.4
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• pp.322-326
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• 2016

The distribution of floodplain vegetation is mainly affected by hydrological and hydraulic processes. In this study, we investigated changes in the vegetation distribution due to flood discharge alteration, and the relationship between the vegetation types and the flood frequency during the last ten-year period in the Cheongmi-cheon Stream. Flood discharge of the Cheongmi-cheon Stream tended to decrease from 2006 to 2016. It has greatly decreased to less than $160m^3/s$ since 2013. This resulted in the settlement of Phragmites japonica to the wide sand bar at the Cheongmi-cheon Stream, even though it had sparse vegetation before 2013. The sand bar was fully covered with P. japonica in 2016. Vegetation communities in the floodplain were classified by dominant species, i.e. the annual-hygrophytic, the perennial hygrophytic and the mesophytic communities. Analysis of the relationship between the vegetation communities and the flood frequency shows the annual hygrophytes, perennial hygrophytes and the mesophytes communities distributed in the range of under 1 year, 1-10 year and over 7 year flood inundation area, respectively. In conclusion, distribution of the floodplain vegetation is closely related with the flood discharge and frequency in the Cheongmi-cheon Stream.