• Geomechanics and Engineering
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• 제15권4호
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• pp.957-964
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• 2018

In this study, a method of electrochemical consolidation is applied. This method utilizes electro-osmosis, which is an effective ground improvement technique for soft clays, and soil treatment using lime, which is the oldest traditional soil stabilizer. The mechanism of lime treatment for soil involves cation exchange, which leads to the flocculation and agglomeration. Five representative laboratory tests-an electro-osmotic test and four electrochemical tests with various proportions of lime-were performed on dredged marine clay. The objectives of this study are to investigate the effect of electrochemical treatment and to determine the optimum dose for optimal consolidation performance of dredged marine clay. The results show that a better consolidation effect was achieved in terms of current, temperature, and vane shear strength by using electrochemical treatment. The best results were observed for the electrochemical test using 4% lime content.

• 한국지반환경공학회 논문집
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• 제22권12호
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• pp.25-32
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• 2021

Geotextile tube technology has been perceived as an economical solution for liquid sludge treatment, and analyzing its consolidation behavior is necessary to be able to evaluate the dewatering capabilities of large geotextile tubes filled with contaminated soil, tailings, sewage sludge, and so on. The objectives of this study are to present a method that can adequately convey the consolidation behavior of geotextile tubes filled with sewage sludge, and to investigate the effects of various geotextile tube consolidation parameters. In this study, variable coefficients of consolidation are utilized to analyze the consolidation process of geotextile tubes filled with sewage sludge. The consolidation solution was verified by comparing the measured and predicted data from a hanging bag test conducted in the literature. After verifying the proposed solution, the consolidation parameters of a geotextile tube composed of a woven polypropylene outer layer and a non-woven polypropylene layer filled sewage sludge were obtained. Using the obtained parameters, the consolidation behavior of a large-scale composite geotextiles tube was predicted.

• Geomechanics and Engineering
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• 제19권5호
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• pp.447-462
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• 2019

The vacuum preloading method has been used in many countries for ground improvement and land reclamation works. A sand cushion is required as a horizontal drainage channel for conventional vacuum preloading. In terms of the dredged-fill foundation soil, the treatment effect of the conventional vacuum preloading method is poor, particularly in Tianjin, China, where a shortage of sand exists. To solve this problem, straight-line vacuum preloading without sand is widely adopted in engineering practice to improve the foundation soil. Based on the engineering properties of dredged fill in Lingang City, Tianjin, this paper presents field instrumentation in five sections and analyzes the effect of a prefabricated vertical drain (PVD) layout and a vacuum pumping method on the soft soil ground treatment. Through the arrangement of pore water pressure gauges, settlement marks and vane shear tests, the settlement, pore water pressure and subsoil bearing capacity are analyzed to evaluate the effect of the ground treatment. This study demonstrates that straight-line vacuum preloading without sand can be suitable for areas with a high water content. Furthermore, the consolidation settlement and consolidation degree system is developed based on the grey model to predict the consolidation settlement and consolidation degree under vacuum preloading; the validity of the system is also verified.

• 한국농공학회:학술대회논문집
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• 한국농공학회 1999년도 Proceedings of the 1999 Annual Conference The Korean Society of Agricutural Engineers
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• pp.569-574
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• 1999

In Soft ground of south-western coast of our country necessity of marine indutrial complex and container facility has been remarkable. Site construction for habor facility is one of the most urgent problems. Consolidation of dredged fill has become important task. In addition, volume change of dredged fill should be examined carefully. This study dealt with consolidation of dredged fill by PCDDF and in order to secure trafficability of heavy equipment for surface treatment should be studied.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제27권6호
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• pp.498-510
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• 2001

Distraction osteogenesis refers to the biological process responsible for new bone formation between bone segments by gradual distraction after osteotomy. For the past several years, various inconveniences including a protracted consolidation period that requires patients to wear a distractor frame longer, as well as higher medical costs, have not been remedied by improvements in osteotomy, distraction rate and monitoring system. Furthermore, side effects such as pin tract infections and soft tissue swelling may arise due to the long treatment period. These drawbacks form the rationale of this study which purports to seek a method by which the consolidation period can be reduced. This paper examines how platelet-rich plasma(PRP), known to facilitate osteogenesis, influences bone formation when applied in distracted area. Ten mongrel dogs, which were made to wear external distractor frames after osteotomy in both sides of the mandible, were used as subjects. After a 7day period of latency, distraction was carried out at a rate of 1mm/day for 14 consecutive days. After the onset of distraction, 2ml of PRP and a mixture of calcium gluconate and thrombine were injected into the center of the distracted callus on the left side of the mandible. The left was injected with PRP while the right side was set as the control site without PRP treatment. Execution at the onset of distraction and in 2 weeks, 4 weeks and 8 weeks after the consolidation period, clinical and radiographic tests, bone mineral density examination, histological examination and histomorphometric analysis were conducted to compare both sides. The results are summarized as follows: 1. Based on the clinical examination at two weeks, more remarkable cortical bone formation was found on the buccal and lingual side of the distracted area in the PRP treatment site than in the control site. No visual difference was found between the PRP treatment site and the control site at four eight weeks. 2. Based on the radiological examination, a distinct increase in the radiopaque appearance of the PRP treatment site was revealed at two weeks, but this increase appeared to slow down at four and eight weeks. 3. Examination of bone mineral density revealed a significant difference at two weeks with the PRP treatment site yielding density two times higher than the control site. This difference lessened after four weeks, and disappeared at eight weeks. 4. The histomorphometric examination revealed that about 20% more bony trabeculae area(20%, higher) was formed in the PRP treatment site than in the control site. In conclusion, it can be said that PRPs effect on stimulating bone formation in the PRP treatment site manifest as early as two weeks. Trabeculae formation likewise increased throughout the whole period. If this result can be applied to humans, the consolidation period can be reduced by injecting PRP into the distracted area.

• 한국컴퓨터정보학회논문지
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• 제6권1호
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• pp.119-129
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• 2001

본 연구는 시군 통합시의 공무원의 처우개선에 대한 통합전후의 의견을 통하여 인식도 조사를 하였다. 이를 위한 지표로 근무평가공정성. 근무지배속 보수 및 수당, 승진, 신분보장, 업무의욕, 역할갈등, 응집도, 의사결정참여 등을 이용하였다. 조사결과, 조사지역인 통합여수시 가 아직 통합한지 2년 밖에 되지 않아 커다란 효과는 기대할 수 없었으나 약간은 개선되는 움임도 나타나고 있었다. 향후 계속적인 처우개선 노력이 필요하다고 본다.

• Geomechanics and Engineering
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• 제24권2호
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• pp.129-141
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• 2021

The vacuum preloading method has been used in many countries for soil improvement and land reclamation. However, the treatment time is long and the improvement effect is poor for the straight-line vacuum preloading method. To alleviate such problems, a novel combined air booster and straight-line vacuum preloading method for shallow ground treatment is proposed in this study. Two types of traditional vacuum preloading and combined air booster and straight-line vacuum preloading tests were conducted and monitored in the field. In both tests, the depth of prefabricated vertical drains (PVDs) is 4.5m, the distance between PVDs is 0.8m, and the vacuum preloading time is 60 days. The prominent difference between the two methods is when the preloading time is 45 days, the injection pressure of 250 kPa is adopted for combined air booster and straight-line vacuum preloading test to inject air into the ground. Based on the monitoring data, this paper systematically studied the mechanical parameters, hydraulic conductivity, pore water pressure, settlement and subsoil bearing capacity, as determined by the vane shear strength, to demonstrate that the air-pressurizing system can improve the consolidation. The consolidation time decreased by 15 days, the pore water pressure decreased to 60.49%, and the settlement and vane shear strengths increased by 45.31% and 6.29%, respectively, at the surface. These results demonstrate the validity of the combined air booster and straight-line vacuum preloading method. Compared with the traditional vacuum preloading, the combined air booster and straight-line vacuum preloading method has better reinforcement effect. In addition, an estimation method for evaluating the average degree of consolidation and an empirical formula for evaluating the subsoil bearing capacity are proposed to assist in engineering decision making.

• 한국지반공학회논문집
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• 제20권2호
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• pp.67-73
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• 2004

준설매립 및 연약지반 처리에 있어 압밀촉진 공법들에 대한 연구가 활발하다. 본 연구에서는 초음파를 사용하여 압밀촉진을 유발하고자 하였고 그 영향 정도를 실내실험을 통하여 조사하였다. 실내시험은 특별히 제작된 압밀시험기를 사용하였으며 압밀시험 중 초음파를 시료에 직접 가할수 있도록 고안되었다. 압밀시험 재료로는 원심력 시험기를 사용하여 원하는 조건에 맞는 동질의 시료를 제작하여 사용하였으며 초음파 강도, 처리 시간을 달리하여 시험을 실시하였다. 시험결과 초음파가 압밀에 미치는 영향은 큰 것으로 나타났으며 초음파 처리의 영향에 미치는 정도가 시험조건에 따라 다르게 나타났다. 본 연구의 결과를 이용하여 초음파에 의해 압밀촉진을 위한 공법개발의 가능성을 파악하였다.

• 보존과학회지
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• 제18권
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• pp.89-96
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• 2006

염을 함유하고 있는 석조문화재들의 표면층은 대부분 매우 약한 상태이기 때문에 강화처리가 필요하다. 이제까지의 연구들은 강화제의 침투깊이와 강화제가 손상된 조직의 역학적 안정성에 끼치는 영향에 대해 주로 다루었다. 그러나 염을 함유한 석조문화재에 에틸실리케이트를 기반으로 한 강화제를 처리했을 때 성공적이지 못한 결과가 보이고 있다. 본 연구에서는 염이$(CaSO_4\;2H_2O,\;NaNO_3)$ 손상된 석조문화재의(Nationalgalerie, Berlin, Germany) 강화효과에 미치는 영향을 살펴보기 위해서 사암시료를 염용액에 담구어 함염처리를 시킨 후에 에틸실리 케이트를 기반으로 하는 강화제를 함침시켰다. 연구결과, 석조문화재가 함유하고 있는 염들은 암석 내의 공극을 채움으로 해서 강화제가 내부로 충분히 들어가지 못하는 차단작용을 하는 것으로 밝혀졌다. 네브라 사암으로 구성된 Nationalgalerie 건물의 강화처리에 에틸실리케이트 계열의 강화제를 사용하고자 한다면 우선 표면오염층에 함유되어 있는 높은 함량의 염을 줄이거나 없애는 작업을 강화처리 전에 선행하여야만 효율적인 강화효과를 거둘 수 있을 것이다. 염을 함유하고 있는 석조문화재를 손상을 악화시키지 않고 강화시키기 위해서는 우선 정확한 염을 파악하여 그 위해성 여부를 고려하고, 암석, 염과 강화제의 상관관계를 시험한 후 적절한 강화제와 사전처리법을 찾는 일련의 선행연구가 필수적이다.

• 대한토목학회논문집
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• 제14권4호
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• pp.953-963
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• 1994

연약 점토 지반의 처리 기술은 고도의 토목공학적인 기술을 요한다. 특히 준설매립토는 액성한계가 크고 자연함수비가 매우 높아 매립재료는 부적합하지만 기술의 발달로 재료의 거동을 예측하여 안정한 재료로 활용할 수있는 단계에 있다. 본 연구에서는 초연약 준설 점토의 침강거동 및 자중 압밀거동의 특성을 알아보고 현장의 상황을 재현한 모형실험으로 얻어진 결과를 현장에서 활용할 수 있는 방안을 모색하고자 하였다. 이를 위해 압밀시험기는 대형으로 제작하였으며 높이와 직경의 변화에 따른 압밀거동의 특성을 고찰해 보고 수치모델로 자중압밀의 거동을 예측하였다.