• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.1727-1734
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• 2008

After the final closure of sea dyke, seepage behaviour of embankment is highly changed by variation of water head different between tide wave and controlled water level at fresh lake. Especially, the seepage behaviour of bottom protection layer of final closure section is more important factor for structural and functional stability of sea dyke, because of the bottom protection layer of final closure section is penetrated sea side to fresh lake. Even though bottom protection layer was filled with dredged fine sand, it has a high permeability. In this paper, mainly described about the seepage velocity and borehole image of bottom protection layer filled with dredged sand after final closure. Various in-situ tests such as BIPS (Borehole Image Processing System) and ABI (Acoustic Borehole Imager) survey, wave velocity measuring, and color tracer survey were conducted to evaluate the seepage behavior of bottom protection layer. Based on the in-situ tests, the bottom protection layer of final closure section was almost filled with dredged sand which is slightly coarse grain sand and there have sea water flow by water head different between tide wave and controlled water level at fresh lake. Also, comply with tracer survey results, the sea water flow path was not exist or generated in the bottom protection layer. However, because of this result not only short term survey but also just one test borehole survey results, additional long term and other borehole tests are needed.

• Proceedings of the Korean Geotechical Society Conference
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• 2008.10a
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• pp.806-813
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• 2008

In this research, mainly research about the structural and functional stability of sea dyke with variation of seepage condition after final closure. The piezometric head (water head in embankment) monitoring system was installed at two representative final closure section. The dredged fine sand filling condition was evaluated by in-situ test results. Also, the numerical analysis was performed to determine the permeability of bottom protection layer filled with dredged fine sand by monitoring results. According to numerical back analysis results, the coefficient of permeability of bottom protection section of is $7.6{\times}10^{-6}$ m/sec. These results are noted that the bottom protection layer of sea dyke was strong and intensively filled with dredged sand. Also, based on the seepage analysis, the seepage flux of this sea dyke was calculated about $2.42m^3$/day/m which is 29% decreased value compare with adjacent sea dyke.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2012.04a
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• pp.460-463
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• 2012

인류의 문제점 중 하나는 환경 및 자원고갈의 문제에 직면해 있는 상황이다. 자원 고갈과 환경 문제를 조금이나마 해소하는 방법으로 폐자원을 이용하는 방법이 있으며 그 중 재활용 방안으로 화력발전소에서 사용 후 폐기물로 분류되는 석탄회를 이용하는 것이다. 국내 석탄회의 발생량은 2004년 현재 500만 톤으로, 2011년 약 700만 톤 이상일 것으로 추정되며, 이중 보일러 저부에서 채취되는 Bottom Ash가 약 20%로 100만 톤 이상 발생되는 것으로 보고되고 있다. 본 연구에서는 자원고갈과 환경오염문제를 해결하기위해 석탄회를 재활용하여 불연성능을 가진 기능성 바닥재 개발을 연구하고자 한다.

• Proceedings of the Korean Geotechical Society Conference
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• 2010.09a
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• pp.29-39
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• 2010

By understanding the construction process of sea dikes and the current state of the thickness and speed of fluid in the bottom layer protection work of final closure gaps, a construction method applicable for the blocking of bottom layer work will be selected. The three construction methods selected will be tested in site through various methods, and the reinforcement of bottom layer protection and impervious effect will be verified. The verification results are as follows: 1) The overall riprap layer were 0.5~1.0m thicker than planned so that the grouting depth and grout input amount increased 2) The applied construction methods permeability of riprap layers were improved from $\alpha{\times}10^{-2}cm/s$ before the construction to $\alpha{\times}10^{-4}cm/s$ after construction. 3) The results of core extraction in order to grossly verify the hardening time and durability allowed the identification of grout injection effect. The amount of filling of the injection was difficult to judge because the slime in many areas made the reading of borehole photography difficult.

• Journal of the Korean Institute of Gas
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• v.8 no.2 s.23
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• pp.54-60
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• 2004

In this paper, the maximum von Mises stress and maximum displacement of the corner protection and secondary bottom structures have been analyzed using a finite element analysis technique. The design criterion of the comer protection is 1,500Pa for a normal nitrogen gas purging process at the beginning stage of start-up procedure. This pressure is very safe for the structure safety of the comer protection and secondary bottom plates. The corner protection and secondary bottom plates fabricated by $9\%$ nickel steel sheet may plastically be distorted and fractured for the increased gas pressure of 8,475Pa, which produces the maximum von Mises stress of 833MPa and maximum displacement of 1.9m at the center of secondary bottom plate.

• Proceedings of the Korea Institute of Fire Science and Engineering Conference
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• 2010.04a
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• pp.377-382
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• 2010

건물의 대형화 고층화로 고강도 콘크리트의 사용이 증대되면서 고강도 콘크리트의 화재 시 폭열 대책이 필요하다. 본 연구는 전국 화력발전소에서 매립되는 Bottom Ash와 EPS를 재활용하여 건축소재의 내화기준에 만족하고 자원순환 소재의 새로운 개발방향을 제시하고자 난연성이 가미된 경량콘크리트 패널을 개발하여 그 난연 성능 및 벽체로서의 성능을 실험하였다. 실험은 Bottom Ash를 활용한 코팅 경량골재를 2개 Type으로 개발하여 단위중량, Flow, 압축강도, 열전도율, 부착강도, 건조수축, 흡수율, 난연 성능을 평가하였다. 그 결과 대부분의 데이터가 KS기준에 맞게 나왔으며, 난연 성능 또한 1급으로 나왔다. 이로서 폐자재인 Bottom Ash와 EPS를 재활용하여 화재 시 난연성능이 확보됨은 물론 국가성장핵심 사업인 녹색성장에 걸맞은 새로운 경량콘크리트 패널을 개발할 수 있게 되었다.

• Journal of the Korean Geosynthetics Society
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• v.5 no.1
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• pp.25-32
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• 2006

Sea dyke construction is simply defined as a cutting procedure of sea water flow. Sea dyke construction is more difficult than in-land construction because it is placed on deep seabed and exposed sea wave attack. Especially, the final closure of sea dyke is most dangerous due to the fast velocity of tidal flow. The final closure is consisted with vast rubble and heavy stone gabion, therefore the discharge velocity at land side of final close section is irregularly and sometime occur the fast discharge velocity. In this paper, the seepage model test performed to evaluate seepage behavior of final closure and continuous sea dyke section such as discharge velocity, hydraulic gradient, and phreatic line with installation of bottom protection filter mat. Based on the seepage model test results, the maximum discharge velocity of final closure section is 1.7m/sec and the discharge velocity is decreased maximum 23.7% with installation of bottom protection filter mat.

• Journal of Ocean Engineering and Technology
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• v.1 no.1
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• pp.84-93
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• 1987

A beach nourishment method can be used as one of the beach erosion protection methods which may keep coastal environments whithout constructing coastal structures on the HAE UN DAE beach. The beach nourishmens is affected by a natural condition and artificial condition;a natural condition includes conditions of bottom slope, diameter of bottom materials and waves, and artificial conditions include deposit position, method, diameter and quantity of the nourishing sand. It has accomplished to obtain the deposit position and the best diameter of the nourishing sand from a two-dimensional hydraulic model test, which simulates the erosional HAE UN DAE beach. In this study, the protection of the beach erosion can be maximized when the nourishing sand of 3.3mm in diameter, which is about 5.5.times of the bottom materials in diameter, is deposited layerly in front of the breaker zone which has a water depth of 4.6m.

• Journal of the Korean Geosynthetics Society
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• v.18 no.4
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• pp.97-106
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• 2019

This study was conducted to propose a reasonable requirement regulation of barrier system of rubble mound revetment offshore landfill for preventing contaminant leakage. The barrier is composed with bottom layer and side barrier. The bottom layer was assumed as impermeable clay layer and side barrier was composed with HDPE sheet (primary element) and mid-protection layer (supplementary element). Seepage-advection-dispersion numerical analysis has been conducted using SEEP/W and CTRAN/W programs under steady flow. As the results, the minimum required barrier regulations for hydraulic conductivity and thickness of the bottom layer were suggested. For side barrier, the extended length of HDPE sheet and the hydraulic conductivity of mid-protection layer were also suggested.

• Proceedings of the KIPE Conference
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• 2018.07a
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• pp.108-110
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• 2018

This paper proposes shortcircuit fault protection method in a synchronous buck converter using the PCB pattern Rogowski coil. The PCB pattern Rogowski coils are embedded in the gate driver to measure the device currents of the top and bottom side. When shortcircuit occurs in the system, the gate signal is blocked by the proposed fault protection method using the device current. The simulation and experimental results show that the proposed fault protection method is verified in the shortcircuit system.