• Journal of the Korean Society for Marine Environment & Energy
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• v.6 no.2
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• pp.38-45
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• 2003

This paper intends to analyze the movement characteristics of the suspended solid(SS) generated in a riprap work which is the most widespread process in harbor construction. The generation and movement behaviors of SS are investigated when 1) basic ripraps (0.001~0.03㎥) are cast for breakwater construction, 2) ripraps are loaded on carrier for riprap casting in the sea-wall construction of dredged material pocket, and 3) ripraps for inner filling are cast. The result of the present study shows that the SS generation is considerable when basic ripraps are cast for breakwater construction and the SS diffusion reaches up to 500m in high tide period. When ripraps are loaded on carrier, the SS is generated by the ripraps running down into sea from carrier, thereby showing a high concentration of SS in the vicinity of carrier. In the surface layer, SS distribution is confined in the vicinity of the carrier due to the prompt sinking of the SS. However the SS in the bottom layer is diffused approximately up to loom and then the SS concentration reaches to the background one. In the riprap (less than 0.03㎥) casting for inner filling using pork crane, SS is diffused approximately up to 300m in the surface layer and more than 300m in the bottom layer. It is quite interesting that the movement of the SS generated in harbor construction is mainly controlled by wind drift in the surface layer and tidal current in the bottom layer, and also the diffusion range of SS in the bottom layer is much larger than that in the surface layer.

• Journal of Wetlands Research
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• v.14 no.2
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• pp.277-288
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• 2012

Estuary is unique habitat ground under substantial changes of water quality, river side, bed material, and micro topography. Construction of SinGok underwater weir with excessive dredging for downstream of weir has changed hydraulic conditions of Han River. This study investigates spatial changes of estuary and expansion process of vegetation on sandbar for JangHang estuary in Han River through analysis of physical and ecological characteristics. As a result of investigation, we found that area of sandbar in JangHang estuary is expanded six times compared between 1985 and 2006, and area of Phragmites australis is gradually decreased while area of Salix subfragilis Anderson. is increased. Also the analysis result of soil layer shows that the Jang-Hang wetlands are created by effect from river, and woody plants are settled from middle part of wetlands, then spread to upper and lower part of wetlands.

• Journal of the Korean Geotechnical Society
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• v.24 no.12
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• pp.85-92
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• 2008

It is necessary to develop a rational design method for surface reinforcement of very soft ground because most current design works rely on merely crude empirical correlations. In this paper, the mechanical behavior of very soft ground that is surficially reinforced was investigated with the aid of a series of numerical analyses. Several material properties of each dredged soft ground, reinforcement and backfill sand mat have been exercised in the numerical analysis. The result of numerical analysis was compared with those of the laboratory model test. Through the matching process between the numerical and experimental result, it is possible to determine representative material properties of the dredged soft ground, reinforcements and backfill sand mat. These verified material properties permit to evaluate the effect of the stiffness of reinforcement and the thickness of sand mat on the overall deformation of the reinforced soft ground.

• Environmental Analysis Health and Toxicology
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• v.20 no.1
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• pp.39-45
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• 2005

Renin-angiotensin system (RAS)은 혈압 조절에 중요한 역할을 수행하는 생리적 조절계로써, 이 system 을 구성하는 유전자들의 이상은 본태성 고혈압의 발병과 유의하게 관련된 것으로 알려졌다. RAS의 주요한 구성 성분인 angiotensin II는 2종류의 수용체인 angiotensin II type I receptor(AT₁R)와 angiotensin II type I receptor(AT₂R)에 의해 그 효과가 매개되기 때문에, 이 수용체를 암호하는 유전자는 본태성 고혈압의 유력한 후보 유전자라고 볼 수 있다. 현재가지의 연구에 의하면, AT₁R 유전자에 존재하는 유전적 변이와 본태성 고혈압과의 관련성에 관해서는 많은 보고들이 있었지만, AT₂R 유전자에 존재하는 유전적 변이 가 본태성 고혈압에 유의한 효과를 나타내는 지에 관해서는 이렇다할 연구 성과가 별로 없는 실정이다. 이에 본 연구에서는 한국인 집단을 대상으로 하여, AT₂R 유전자에 존재하는 C3123A 다형성이 한국인 집단에서 본태성 고혈압과 유의한 관련성이 있는 지를 분석하였다. 이 유전자는 인간의 X 염색체에 존재하기 때문에, 여성인 경우에는 CC, CA및 AA로 이루어진 3유전자형이 존재하지만, 남성인 경우에는 C와 A로 이루어진 2종류의 대립 유전자로 구성되어 있기 때문에, 본 연구에서는 남성과 여성을 개별적으로 나누어서 분석하였다. 연구 결과, AT₂R 유전자에 존재하는 C3123A 다형성은 남녀 모두에서 본태성 고혈압과 유의한 관련성을 나타내지 않았다(P>0.05). 그렇지만, 이 다형성에 대한 대립 유전자 빈도를 서양인 집단과 비교했을 경우에는, 한국인을 대상으로 한 본 연구에서 A 대립 유전자 빈도가 0.33인 반면에 서양인 집단은 그 빈도가 0.43～0.48로 한국인 집단보다 높은 값을 나타내었다. 따라서, AT₂R 유전자에 존재하는 C3123A 다형성과 본태성 고혈압과의 관련성에 대해서는 한국인과 유전적 배경이 다른 서양인 집단을 대상으로 한 추시가 필요할 것으로 사료된다.

• Journal of the Korean Geotechnical Society
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• v.22 no.8
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• pp.55-62
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• 2006

The design of sand mat should be reviewed by the behaviour of excess pore pressure which is obtained by combining characteristics of soft ground with the permeability of sand mat. In this paper, in order to investigate the distribution of hydraulic gradient of sand mat, a banking model test was performed using dredged sand as materials of sand mat, and these results were compared by the numerical analysis results utilizing Terzaghi's consolidation equation. The results show that the pore pressure was influenced by the settlement increasing in the central area of sand mat as the height of embankment increases, and uprising speed of excess pore pressure due to residing water pressure is delayed compared with the results of numerical analysis. Finally, the construction of sand mat should be spreaded to reduce the increased hydraulic gradient at the central area of embankment.

• Proceedings of the Korea Water Resources Association Conference
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• 2020.06a
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• pp.31-31
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• 2020

가뭄 발생 시 국내 농어촌 지자체 대부분은 추가 수원공 확보를 위한 긴급 대책으로 신규 관정을 개발하거나, 저수지와 하천을 준설하여 가뭄 수요에 대응하는 편이다. 이러한 방법은 즉시 대응에는 효과가 있지만, 고가의 비용이 소요되고, 무엇보다도 국지적으로 가뭄이 빈번하게 발생하는 지역에는 적용에 한계가 있다. 이러한 한계를 극복하기 위하여, 최근 기설 관정을 연계 이용하여 지하수 공급 극대화를 도모하는 기술이 제안되었다. 그런데 기설 관정 연계 이용 시 가장 중요한 사항은 모든 관정에서 최대 양수량을 유지하며 지하수를 공급할 수 있도록 관리해야 하는 점이며, 특히 암반관정의 과잉양수로 인한 간섭현상으로 충적관정이 고갈되어 공급가능한 지하수 수량이 오히려 감소되는 것을 사전에 방지하여야 한다. 이 연구에서는 가뭄 발생 시 암반관정(양수정)에서 최대로 양수했을 때에도 주변 충적관정의 양수능이 유지되는 최소 지하수위를 「지하수위 저하 한계치」로 지정하여 관정 연계 이용의 최적화를 도모하였다. 지하수위 저하 한계치 산정을 위하여, Theis의 자유면 대수층 정상류 우물수리 방정식과 지하수영향반겅 설정에 관한 경험식(Schultz, Weber, Kozeny 및 Jacob 경험식)을 이용하였다. 그런데 지정된 지하수위 저하 한계치는 충적관정의 지하수위이므로, 암반관측공만 소재하는 지역에 대해서는 충적층 지하수위 변동과 암반층 지하수위 변동 간의 상관분석을 통해 암반 관측공의 지하수위 저하 한계치를 추정하였다. 이후, 양수시험 자료(양수정과 주변 관측공의 수위변동 자료)를 이용하여 지하수 대수층의 이방성을 확인하였고, 이를 통해 암반관정의 양수에 따른 간섭을 크게 받는 충적관정과 그렇치 않은 충적관정을 구분하여 이방성에 따른 지하수위 저하 한계치를 수정하고, 상습가뭄 발생지역의 암반관정과 충적관정의 최적 지하수 양수를 도모하였다.

• Journal of the Korean Society of Marine Environment & Safety
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• v.24 no.4
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• pp.438-444
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• 2018

Korea has recently selected twenty-two ports for reinforcement breakwater installation of protection facilities, due to rise sea level caused by global warming and increase in the number of typhoon and tsunami. In addition, due to consistent enlargement of ship size, dredging for depth of water for large vessel's berthing and enlargement of berth is under construction. However, no definite construction plan for the reinforcement and lengthening of crown height, which has close relationship with the safe mooring of ships. In this study, domestic and foreign design criteria of crown height were analyzed, and the crown height evaluation index and evaluation method were developed by dividing it into environment and ship elements. In particular, in the case of ship evaluation index, each step was set up in 4 steps according to domestic and foreign regulations, weighted by each step, and the safety level of crown height was evaluated. As a result of the mooring safety simulation of the 100,000 ton cruise ship, the appropriate minimum crown height standard was derived to be 3 m above A.H.H.W. The results of this study are expected to be used as basic data to propose the crown height standard reflecting ship characteristics.

• Journal of the Korean Society of Marine Environment & Safety
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• v.25 no.6
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• pp.687-697
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• 2019

By monitoring sediment grain size and level variation of tidal flat surface for 6 years (2005-2011), and also by mooring TISDOS (tidal-flat sediment dynamics observation system) on the low intertidal flat in 2008, we investigated the sedimentary environment of tidal flat in the dammed Yeongsan River Estuary. The tidal flat of the Yeongsan River Estuary lost 82 % of its area because of coastal development projects, and a narrow tidal flat below mean sea level now remains. Most of the tidal flat sediments are composed of silt up to 70-94 %, and show the characteristics of clay deficiency and silt dominance. This is closely related with the coastal development, which led to the destruction of high tidal flats where most mud settled, and the modification of tidal current patterns. Moreover, the estuarine tidal-flat sediments reveal seasonal variation. They are coarse with abundant silt during windy autumn to spring, fine with abundant clay during the less-windy and high-discharge summer. This phenomenon indicates that the behavior of sediment particles on the low intertidal flats of the Yeongsan River Estuary is influenced by wind waves for silt and fresh water discharge and the tidal process for clay. Monitoring results of the altitude of tidal flat surface showed that the study area had eroded at an average rate of -2.6 cm/y during the period of 2005-2011, and also that an unusual deposition with a rate of 4 cm/y occurred in 2010. The erosion can be explained by an increased tidal amplitude and a strengthened ebb-dominant tidal asymmetry after the construction of an estuary dike and the Yeongam Kumho Seawall. The deposition in 2010 seems to have been closely related to the mass production of suspended materials from dredging of the estuary.

• Journal of the Korean Society of Marine Environment & Safety
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• v.26 no.1
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• pp.31-38
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• 2020

The characteristics of ship traffic routes and the long term fluctuation in marine traf ic volume of the incoming and outgoing routes of the Yeosu Gwangyang Port were analyzed using vessel traffic data from the past 22 years and a real-time vessel traffic volume survey performed for 72 hours per year, for three years, between 2015 and 2017. As of 2017, the number of vessels passing through Yeosu Gwangyang Port was about 66,000 and the total tonnage of these ships was about 804,564 thousand tons, which is a 400 % increase from the 189,906 thousand tons shipped in 1996. Specifically, the dangerous cargo volume was 140,000 thousand tons, which is a 250 % increase compared to 1996. According to the real-time vessel traffic volume survey, the average daily number of vessels was 357, and traf ic route utilization rates were 28.1 % in the Nakpo sea area, 43.8 % in the specified sea area, and the coastal area traf ic route, Dolsan coastal area, and Kumhodo sea area showed the same rate of 6.8 %. Many routes meet in the Nakpo sea area and, parallel and cross passing were frequent. Many small work vessels entered the specific sea area from the neighboring coastal area traffic route and frequently intersected the path of larger vessels. The anchorage waiting rate for cargo ships was about 24 %, and the nightly passing rate for dangerous cargo ships such as chemical vessels and tankers was about 20 %. Although the vessel traffic volume of Yeosu Gwangyang Port increases every year, the vessel traffic routes remain the same. Therefore, the risk of accidents is constantly increasing. The route conditions must be improved by dredging and expanding the available routes to reduce the high risk of ship accidents due to overlapping routes, by removing reefs, and by reinforcing navigational aids. In addition, the entry and exit time for dangerous cargo ships at high-risk ports must be strictly regulated. Advancements in the VTS system can help to actively manage the traffic of small vessels using the coastal area traffic route.

• The Journal of Engineering Geology
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• v.9 no.2
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• pp.161-176
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• 1999

The objectives of this study are to analyze the changes of geo-surface topography in the Siwha embankment and the Ahsan city area by the image processing of Landsat Thematic Mapper data, and to estimate the reclaimed amount of the exposed tidal flat in the Siwha area using the GIS. False color composite, Tasseled cap, NVDI(normalized difference vegetation index), and supervised classification techniques were used to analyze the distribution of sediments and the aspect of topographical variations caused by artificial human actions. The total amount of the exposed tidal flat was estimated on the basis of the database snch as aerial photography, hydrographic chart, geological map, and scheme drawing in the Siwha area. The possible excavation regions for a seawall were predicted analyzing the supervised classification image of Landsat TM data. Tasseled cap images were used to observe the distribution of sediments. The difference of the NDVI images between spring and summer seasons indicates that deciduous and coniferous forests were distributed over the whole areas. The total fill-volume of the exposed Siwha tidal flat and the fill-volume of the construction planning seawall were calculated as $581,485,354\textrm{m}^3{\;}and{\;}3,387,360\textrm{m}^3$, respectively, from the digital terrain analysis. Daebu Island, Sunkam Island, and the part of Songsan-myeon were chosen as the cut area to make the seawall, and their cut-volumes were estimated as $5,229,576\textrm{m}^3,{\;}79,227,072\textrm{m}^3,{\;}and{\;}47,026,008\textrm{m}^3$, respectively. Therefore, the cut-volume of Daebu Island alone among three areas was sufficient to make the seawall.