• International Journal of Naval Architecture and Ocean Engineering
• /
• v.5 no.4
• /
• pp.598-613
• /
• 2013

This paper deals with the dynamic effect of pipeline installation and embedment for the on-bottom stability design of offshore pipelines on soft clay. On-bottom stability analysis of offshore pipelines on soft clay by DNV-RP-F109 (DNV, 2010) results in very unreasonable pipe embedment and concrete coating thickness. Thus, a new procedure of the on-bottom stability analysis was established considering dynamic effects of pipeline installation and pipe-soil interaction at touchdown point (TDP). This analysis procedure is composed of three steps: global pipeline installation analysis, local analysis at TDP, modified on-bottom stability analysis using DNV-RP-F109. Data obtained from the dynamic pipeline installation analysis were utilized for the finite element analysis (FEA) of the pipeline embedment using the non-linear soil property. From the analysis results of the proposed procedure, an optimum design of on-bottom stability of offshore pipeline on soft clay can be achieved. This procedure and result will be useful to assess the on-bottom stability analysis of offshore pipelines on soft clay. The analysis results were justified by an offshore field inspection.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2010.03a
• /
• pp.595-598
• /
• 2010

Many economical and efficient methods such as sand drain method(SD), plastic board drain(PBD), sand compaction pile, vacuum consolidation method, etc., have been used for soft grounds. The case of sand compaction pile has an effect on accelerating consolidation and increasing bearing capacity by penetration at regular intervals under soft grounds for reducing the drainage path. But, this method has caused not only the nature damage by extracting the sands indiscreetly but also the economical problem for importing the sands because it needs so much sand to make the sand compaction pile. Thus, this study choosed the bottom ash which has similar engineering characteristics with sand. It was performed that clogging test and large direct shear test changing the bottom ash replacement ratio in soft ground for studying strength characteristics of soft ground using bottom ash compaction pile. As a result of the test, the internal friction angle was largely increased and the cohesion was decreased as the replacement ratio increased.

• Elastomers and Composites
• /
• v.57 no.4
• /
• pp.205-214
• /
• 2022

Research on reducing the thickness of polyethylene terephthalate (PET) bottles is necessary to reduce the amount of plastic used. However, as decreasing a PET bottle's thickness weakens it, a robust bottle design is required. Therefore, in this study, we numerically analyzed various bottom designs of a carbonated soft drink PET bottle with 245 and 500 ml capacities and complicated petaloid shapes. Deformation, equivalent stress, maximum principal stress, and its direction according to each design were analyzed to study the strength of the bottle. The results serve as a reference to design robust petaloid PET bottle bottoms with a reduced thickness for carbonated soft drinks.

• KSCE Journal of Civil and Environmental Engineering Research
• /
• v.32 no.4C
• /
• pp.139-147
• /
• 2012

In this study, various laboratory tests using bottom ash, which has similar engineering properties with sand, were conducted in order to solve the problem of clogging in granular compaction pile and to address sand supply and demand. In particular, testing was performed to help reduce clogging and minimize voids in a crushed stone compaction pile constructed in soft ground. Based on compaction tests and large diameter direct shear tests, an optimum mixing ratio was determined to be 80:20 (crushed stone to bottom ash) because an 80:20 mixing ratio showed the highest shear strength. Test results showed that as the bottom ash content increased above 20%, internal friction angle decreased. Another test method showed freezing and thawing had little effect when the replacement ratio was over 40%. Therefore, bottom ash mixed compaction piles in soft ground are most economical at a 40% replacement ratio.

• Proceedings of the Korean Geotechical Society Conference
• /
• 2005.03a
• /
• pp.537-544
• /
• 2005

We find out many soft ground deep excavation cases where results of careless overexcavation accelerate the advance of loosening zone of adjacent ground, bucklings of struts and bottom heaves happen due to delayed supporting time. This article introduces a soft ground deep excavation case where steel pipe sheet piles were used with struts as an earth retaining system. There were 2 times of buckling in the supporting system and heaving of bottom ground due to overexcavation and insufficient penetration depth of the steel pipe sheet piles. The effort of this article aims to improve and develop the technique of design and construction in the coming projects having similar ground condition and supporting method.

• International Journal of Highway Engineering
• /
• v.20 no.4
• /
• pp.21-26
• /
• 2018

PURPOSES : The objective of this study is to evaluate the application of soil stabilization method for soft shoulder construction in the iRoad Project of Sri Lanka. METHODS : Firstly, the quantitative analysis of soil strength improvement due to soil stabilization was done for soil samples collected from iRoad construction sites. Two types of soils were selected from iRoad Project sites and prepared for soil stabilization testing by the Road Development Authority. Secondly, the appropriate stabilizer was selected at given soil type based on test results. Two different stabilizers, ST-1 and ST-2, produced in Korea were used for estimating soil strength improvements. Finally, the optimum stabilizer content was determined for improving shoulder performance. The uniaxial compressive strength (UCS) test was conducted to evaluate the strength of stabilized soil samples in accordance with ASTM D 1633. The use of bottom ash as a stabilizer produced from power plant in Sri Lanka was also reviewed in this task. RESULTS : It is found from the UCS testing that a 3% use of soil stabilizer can improve the strength up to 2~5 times in stabilized soft shoulder soils with respect to unstabilized soils. It is also observed from UCS testing that the ST-1 shows high strength improvement in 3% of stabilizer content but the strength improvement rate with increase of stabilizer content is relatively low compared with ST-2. The ST-2 shows a low UCS value at 3% of content but the UCS values increase significantly with increase of stabilizer content. When using the ST-2 as stabilizing agent, the 5% is recommended as minimum content based on UCS testing results. Based on the testing results for bottom ash replacement, the stabilized sample with bottom ash shows the low strength value. CONCLUSIONS : This paper is intended to check the feasibility for use the soil stabilization technique for shoulder construction in Sri Lanka. The use of soil stabilizer enables to improve the durability and strength in soft shoulder materials. When applying the bottom ash as a soil stabilizer, various testings should be conducted to satisfy the specification criteria.

• ALGAE
• /
• v.20 no.4
• /
• pp.369-377
• /
• 2005

Seashore joining with land and sea, which is typical habitat for marine macroalgae, is classified two types of shore as soft- and hard-bottom shore according to topographical (geological) and ecological features. We compared two of Ulva pertusa Kjellman from two contrasting habitats, sandy (soft-bottom, Haenam) and rocky shore (hard-bottom, Hadong) in terms of chlorophyll-a fluorescence and its parameters, and various photosynthetic pigment and nutrient content in the tissue of those. Both of habitats were different in the light environment such as light attenuation coefficient and even in nutrient concentration of ambient seawater. Electron transport rate (ETR) of Ulva from sandy shore was higher than from rocky shore. The range of photosynthetic pigment content in the tissue of U. pertusa was significantly much more in from sandy shore, and also nitrogen and phosphorus content were significantly higher except for carbon content. However, there were no significant differences in the ratio of among photosynthetic pigments, and N:P ratio was similar between each other, even though significantly different. Our result implied on the reason of why most of green tides in the worldwide concentrated and frequently occurred at sites with sandy, muddy and silty bottoms, being classified as soft-bottom shore.

• Proceedings of the Korean Information Science Society Conference
• /
• 2002.10c
• /
• pp.433-435
• /
• 2002

최근 real-time 시스템들이 많이 개발되어 상용화되고 있고, 여러 산업분야에 적용되고 있다. 한편 리눅스 운영체제의 사용이 증가하고 안정화됨에 따라, 이 시스템에 real-time 기능을 추가하기 위한 노력으로 여러 프로젝트가 진행 중에 있다. 이 가운데 시스템간에 네트웍 패킷을 송수신하고 이를 처리하는 과정에 대해 본 논문은 soft real-time을 적응하고자 한다. 기존 방식은 TOP HALF와 BOTTOM HALF로 인터럽트 처리과정을 나누어 BOTTOM HALF의 크기와 시스템 콜의 사용 빈도에 비례하여 종료시간을 예측할 수 없다. 이에 본 논문에서는 real-time 네트웍 패킷을 좀더 신속히 처리할 수 있도록 네트웍 인터럽트 처리 방안을 소개하고자 한다.

• Proceedings of the Korean Society for Technology of Plasticity Conference
• /
• 2001.10a
• /
• pp.154-157
• /
• 2001

Through this study we investigated the causes of bottom crack. We then redesigned petaloid bottom to prevent bottom crack. We examined the material property variations according to the stretch ratio of PET and analyzed stretches of bottom in blowing processes. We also performed crack test to observe a crack phenomena. The effective stress and maximum principal stress were examined by computer simulation. We concluded that the bottom crack occurs because of not only insufficient strength of material due to the insufficient stretch of PET but also coarse design of petaloid shape. The highest maximum principal stress occurred at valley in petaloid bottom of bottle and this strongly affected the crack in bottom. We redesigned petaloid shape to minimize maximum principal stress, and this result in increasing the crack resistance.

• Journal of the Korea institute for structural maintenance and inspection
• /
• v.15 no.6
• /
• pp.85-91
• /
• 2011

This study aims at evaluating feasibility of Bottom ash-mixed Foam Cement Banking(BFCB) Method on the enhancement of soft soil, which is developed to reduce self-weight of banking by applying bottom ash and foam. to cement slurry. In order to measure the behavior of soil when BFCB layer was covered to soft ground, a testing equipment for mock-up test was fabricated and phased loads were applied up to measurement of yielding and ultimate strengths as well as movement of ground particles. In addition, these measured values such as settlement and heaving were compared with ones of surface-hardening method prevailing on soil improvement. As the result through mock-up test, BFCB showed lower values of ground deformation, while wider range of deformation was observed in compare to the other method. And settlement and heaving were measured lower, which implies the method developed is very effective to applicability of soft ground.