• KCID journal
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• v.6 no.1
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• pp.39-47
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• 1999

One of the important features of a beach face is the dynamic response to the ever-changing waves and tides imposed from the body of water. Furthermore, human activities at or near the beach can enforce the characteristic changes on tidal motions and wave

• Proceedings of KOSOMES biannual meeting
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• 2018.06a
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• pp.206-206
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• 2018

• Proceedings of the KSEEG Conference
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• 2007.04a
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• pp.208-211
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• 2007

• Proceedings of the KSEEG Conference
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• 2007.04a
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• pp.481-483
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• 2007

• The Korean Journal of Quaternary Research
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• v.14 no.1
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• pp.1-5
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• 2000

During the last three years (1997∼2000), a research project of beach dynamic environmental process and dynamic nature of the Nobong Beach, East Sea of Korea has been carried out for a better understanding of beach cycle (winter and summer). In fact, however, this paper deals with a particular feature of beach dynamics, that is, overwash process of overwash water and its sediments. The overwash mark sediments (OMS) are analyzed to understand various textural characters.

• Journal of Korean Society of Environmental Engineers
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• v.39 no.5
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• pp.288-302
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• 2017

Accurate measurement of benthic nutrient fluxes (BNF) is a prerequisite for evaluating the effect of sediments on nutrient cycle in the surface water. The intact sediment cores were collected in July 2015 at the midstream of Nakdong River. We identified pre-incubation time (6, 12, 24 hr), dissolved oxygen concentration (90, 70, 50% saturation), diffusive boundary layer thickness (0, 0.6-0.8, 1.2-1.4 mm), and incubation temperature (10, 17, 20, $25^{\circ}C$) as the most important control factors, and measured the BNF fluctuation with the variation of these factors using the laboratory sediment core incubation method. Since the chemical composition, redox condition, hydrodynamic regimes and microbial activities at the sediment-water interface were changed as a result of the alteration of control factors, sediment core incubation should be conducted under as close to the natural conditions of study site as possible, in order to produce the results similar to actual values. Relative percentage differences between two replicates were below 20% in most control factors, which showed satisfactory precision for strict compliance with the experimental conditions and procedures. In the further studies, we will compare the results of core incubation with those of in situ measurements to confirm the accuracy of the sediment core incubation method.

• Journal of Korean Society of Coastal and Ocean Engineers
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• v.16 no.4
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• pp.224-232
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• 2004

Sedimentation changes related with bottom shear stress attenuation at JangHang channel in the Keum River Estuary, where several huge coastal constructions including an estuarine dam have been conducted for last 2 decades, were evaluated for 7 cases to figure out passage hindrance through the channel by a hydrodynamic model using hind-casting technique from 1988 to 2000 at every 2 years interval. Due to the construction of Keum River Estuary Dam, the maximum bottom shear stress rapidly lessened to $0.2-0.6N/m^2$ compared to$1-2N/m^2$ in natural status. Especially it marks below the critical shear stress of $0.4N/m^2$ resulting in severe siltation in the channel just after the closing of dam gates in 1994. It is concluded that the dam may block the tidal energy propagation to upstream and directly results in sedimentation environment in front of dam site. It is also revealed that at least 20% of passage hindrance of small fishing boats through the channel could be counted due to sedimentation by analysis of predicted mean spring tides.

• Journal of Korean Society of Environmental Engineers
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• v.28 no.5
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• pp.472-479
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• 2006

In this research, speciation of phosphorus in sediment and overlying water dependent upon pH and ORP(Oxidation Reduction Potential) was studied. Three possible conditions were simulated: open system with circulation, closed system with stratification and closed system with sand capping on the sediment. Phosphorus release rate from sediment was increased for both open system and closed system if pH was less than 6.0. Phosphorus concentration for closed system was increased from 0.9 mg/L to 0.51 mg/L, and stabilized at 0.34 mg/L if anaerobic conditions were maintained in the overlying water. When sand capping was implemented, phosphorus concentrations of overlying water were maintained less than those of closed system.

• Proceedings of the Korea Water Resources Association Conference
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• 2015.05a
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• pp.305-305
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• 2015

도심지에서의 우수관거시스템의 경우 적정 설계빈도 기준에 따라 유입량에 따른 적정 통수능을 확보할 수 있도록 설계되고 있다. 유입량에 동반되는 토사량의 경우 관내 퇴적 방지를 위한 적정 설계유속 조건 반영을 통해 관내 퇴적이 이루어지지 않도록 고려하고 있다. 그러나 2011년 7월 우면산 토사피해, 2014년 8월 금정산 토사피해와 같이 실제 발생한 주요 침수피해들의 경우 다양한 피해발생 원인들 중 관로 내 토사퇴적에 따른 우수관로의 통수능력의 저하되는 문제점이 지적되었다. 설계 시 적절히 고려하지 못한 토사의 유입은 관내 토사 퇴적으로 이어지고 결과적으로 통수단면 저하에 따른 월류발생 및 도심지 내 침수피해가 발생으로 이어지게 된다. 따라서 이러한 문제를 해결하고 기존 관거의 통수능력을 적절히 확보하기 위해서는 관거 내의 퇴사량에 대한 분석과 이를 고려한 관로 설계가 필수적이다. 도시유역에서 일반적인 우수관거로 유입되는 토사의 경우 산지유역과 달리 비교적 작은 입경을 가진 토사들로 구성된다. 즉, 유입되는 토사량에 있어 입경의 적정 크기 및 분포에 따라서 관거내 토사 퇴적량이 달라지게 되며 이를 해소할 수 있는 유속 범위에 대한 분석이 필요하다. 본 연구에서는 토사 입경별 관내 유속에 따른 퇴적양상을 검토하기 위하여 특정 제원의 관거 및 우수관거로 유입되는 토사의 입경들을 기준으로 관내 수심의 변동에 따른 우수관거를 지나는 각입자별 부유 퇴적의 기준이 되는 한계유속 조건을 산정하였으며, 이를 고려한 관거의 경사도 조정을 통해 설계유량에 따른 관거 내 토사퇴적량 변화를 살펴보았다. 이때, 관로내에 일정량의 토사가 지속적으로 유입되는 것으로 가정하였으며, 유입되는 토사의 입경을 0.1mm~30.0mm까지 세분화하여, 유입되는 토사 전량에 대한 입경을 하나의 입경으로 고정시킨 조건으로 관내 유속에 따른 퇴적 양상의 변화를 검토하였다. 향후 해당 조건을 반영한 설계방안의 경우 설계강우에 대한 고려를 통하여 신뢰도 측면에서 관거내 토사의 퇴적과 유속 관계에 대한 분석을 바탕으로 이루어져야 하며, 이를 통하여 일반적인 관거의 설계 기준이 수립될 필요가 있다고 판단된다.

• Journal of the Korean earth science society
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• v.25 no.7
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• pp.615-628
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• 2004

In order to elucidate seasonal sedimentary characteristics and depositional environment after construction of seawall on macrotidal flat, a seasonal observations of surface sediments (total 450) and sedimentation rates on 4 transects have been investigated for 2 years. The eastern area of Iwon tidal flat, has been changed from semi-closed coast to open coast by construction of seawall, shows general seasonal changes similar to characteristics of open coast type, which represented both fining and bad sorted distribution due to deposition of fine sediments under low energy condition in the summer, and relatively coarser and better sorted distribution because of erosion of fine sediments in the winter. In considering angles of transects, distribution patterns of surface sediments, the northern and southern parts of eastern tidal flat are dominantly influenced by wave and tidal effects, respectively. As time goes by, the eastern tidal flat shows coarsening-trend of surface sediments caused by direct effect of tidal current, were and typhoon. Meanwhile the western area of seawall, which has been re-formed by construction seawall, is sheltered from northwesterly seasonal wind. The seasonal change pattern of western area of seawall is slightly different from that of eastern tidal flat. Mean grain size and sorting of surface sediments during spring is finer and worse than those during summer. This seasonal change pattern maybe influenced by topographic effects caused from the construction of seawall. In consideration of all result, the transport of fine sediments in the study area, which is supplied to limited sediments, shows clockwise circulation pattern that fine sediments are transported from the eastern tidal flat to the western area of seawall because of blocking of seawall in the winter and are transported reversed direction the summer. As a result, many changes have been observed in the study area after construction of seawall; however, this change is still in progress and is expected to need continuous monitoring.