• Geomechanics and Engineering
• /
• 제28권2호
• /
• pp.157-169
• /
• 2022

Preloading of soft clays is a common ground stabilization method for improvement of compressibility and the undrained shear strength. The waiting period under preload is a primary design criterion controlling the degree of improvement obtained. Upon unloading the overconsolidation attained with respect to actual loads defines the long term performance. This paper presents a laboratory study for investigation of creep behavior of Famagusta Bay alluvial soft soil preloaded under various effective stresses for analysis of long term performance based on the degree of overconsolidation. Traditional one-dimensional consolidation tests as well as modified creep tests are performed on reconstituted soft specimens. Compressibility parameters are precisely backcalculated using one dimensional consolidation theory and the coefficient of creep is determined using the traditional Cassagrande method as well as two modified methods based on log cycles of time and the inflection of the creep curve. The test results indicated that the long term creep can be successfully predicted considering the proposed method. The creep coefficients derived as part of this method can also be related to the recompression index (recompression index, swelling index) considering the results of the testing method adopted in this study.

• Geomechanics and Engineering
• /
• 제8권1호
• /
• pp.113-132
• /
• 2015

In this study, lime (L), silica fume (SF), and lime-silica fume (L-SF) mix have been used for stabilizing and considering their effects on the soft clay soil. The improvement technique adopted in this study includes improving the behaviour, of a square footing over soft clay through grouting the clay with a slurry of lime-silica fume before and after installation of the footing. A grey-colored densified silica fume is used. Three percentages are used for lime (2%, 4% and 6%) and three percentages are used for silica fume (2.5%, 5%, 10%) and the optimum percentage of silica fume is mixed with the percentages of lime. Several tests are made to investigate the soil behaviour after adding the limeand silica fume. For grouting the soft clay underneath and around the footing, a 60 ml needle was used as a liquid tank of the lime-silica fume mix. Slurried silica fume typically contains 40 to 60% silica fume by mass. Four categories were studied to stabilize soft clay before and after footing construction and for each category, the effectiveness of grouting was investigated; the effect of injection hole spacing and depth of grout was investigated too. It was found that when the soft clay underneath or around a footing is injected by a slurry of lime-silica fume, an increase in the bearing capacity in the range of (6.58-88)% is obtained. The footing bearing capacity increases with increase of depth of grouting holes around the footing area due to increase in L-SF grout. The grouting near the footing to a distance of 0.5 B is more effective than grouting at a distance of 1.0 B due to shape of shear failure of soft clay around the footing.

• Journal of Korean Dental Science
• /
• 제17권2호
• /
• pp.84-91
• /
• 2024

Achieving both esthetic and functional implant rehabilitation is crucial for the successful treatment of the anterior maxilla. Adequate peri-implant alveolar bone and soft tissue are essential for optimal rehabilitation of the esthetic area, and there is a direct association between the implant position and prosthetic outcomes. Immediate provisionalization may also be advantageous when combined with augmentation. This case report described the implant placement in a 25-year-old female patient who had lost her right maxillary lateral incisor (#12) due to trauma-induced avulsion. The treatment involved simultaneous grafting and collagenated, deproteinized bovine bone mineral, along with subepithelial connective tissue taken from the right maxillary tuberosity. A polyetheretherketone abutment and non-functional immediate provisionalization were performed by removing both the proximal and occlusal contacts on the composite resin crown. Clinical and radiographic evaluations revealed maintenance of stable ridge contour aspects for six months following surgical treatment. In summary, implant rehabilitation in the esthetic zone can be successful using simultaneous soft and hard tissue grafts. Moreover, soft tissue stabilization post-subepithelial connective tissue grafting can be achieved through early or immediate visualization, along with immediate implant placement.

• 한국안전학회지
• /
• 제23권4호
• /
• pp.42-46
• /
• 2008

Ionizers are essential in various areas of manufacturing industries to protect electrostatic hazards and to reduce inferior products. For ion sources used in the charge neutralizers, there are corona discharge, soft X-ray, ultraviolet and glow discharge. Glow discharge has lots of attractive properties, such as lower discharge sustaining voltage, no generation of ozone, and so on. In this paper, we did an experimental study to trace the mechanism and stabilization of atmospheric pressure glow discharge using the several size and shape of electrodes. As an experimental result, to sustain conditions of atmospheric pressure glow discharge is that discharge voltage is 360V, discharge current is 12mA, apply frequency is 1kHz between electrodes when positive electrode is molybdenum(Mo) and negative electrode is copper(Cu). We confirmed that the mechanism and stabilization of atmospheric glow discharge is deeply concerned with the shape and material of electrode for discharge. Especially, glow discharge in atmospheric pressure was well generated and sustained according with the physical properties used electrode materials, example melting point, thermal conductivity, and etc.

• 한국정보통신학회:학술대회논문집
• /
• 한국해양정보통신학회 2001년도 춘계종합학술대회
• /
• pp.423-426
• /
• 2001

본 논문에서는 전압 안정화 특성을 갖는 전자식 강압형 변압기가 제안된다. 제안된 전자식 변압기는 다음과 같은 특징을 갖는다. 1) 무게가 1kW 기준 일반 변압기의 40% 수준이다. 2) PWM 제어에 의하여 입력전압의 변동에 무관한 출력전압을 유지하는 전압 안정화 기능을 갖는다. 3) 전원 또는 부하단의 Emergency에 대하여 회로 차단기의 기능도 갖는다 4) 부하에 최기 전원 공급시, 낮은 전압으로부터 점진적으로 증가시켜가면서 전원을 인가하여, 전원 투입시 발생한 수 있는 돌입전류나 과도 충격을 제거할 수 있다. 그 밖에 무부하시 전원차단 기능과, 왜곡된 입력전압에 대한 보상기능을 추가 할 수 있다. 본 논문에서는 제안된 강압형 전자식 변압기의 회로 구성과 특징을 설명하고, 이를 PSPICE 시뮬레이션을 통하여 동작특성을 보인다.

• Journal of Yeungnam Medical Science
• /
• 제20권1호
• /
• pp.13-27
• /
• 2003

In the past, the report of shoulder instability undergoing open shoulder stabilization had satisfactory outcomes of greater than 90%. However, the functional loss of open procedure is severe in abduction and external rotation especially. Current arthroscopic techniques for shoulder instability result in success rate equal to open surgical procedure when the labrum is properly fixed to the glenoid rim using suture anchors, the capsule is tightened, and associated bony and soft tissue pathology is addressed. The arthroscopic surgery facilitates the view within shoulder joint for more accurate diagnosis, reduces operating time, minimises postoperative pain, reduces operative morbidity, improves shoulder function, and provides the possibility to perform other procedure simultaneously. However, to accomplish a successful arthroscopic stabilization procedure and to prevent complications, numerous advanced arthroscopic skill must be mastered. Although the arthroscope provides means to visualize new lesions, the pathomechanism and biomechanical explanation is not clear yet. Further studies are necessary to develop for shoulder reconstruction.

• 한국안광학회지
• /
• 제16권1호
• /
• pp.21-30
• /
• 2011

목적: 소프트렌즈를 얼라인먼트(alignment) 피팅 또는 스팁(steep) 피팅하였을 때 각막에서의 렌즈의 회전 움직임, 순목에 의한 이동거리 및 중심위치가 정상안과 건성안에서 어떠한 차이를 보이는지 알아보고자 하였다. 방법: 20~30대 남녀 40안을 정상안군과 건성안군으로 분류한 후 polymacon 재질의 소프트렌즈를 얼라인먼트 피팅 혹은 스팁피팅상태로 착용시키고 렌즈 착용 직후 및 눈물층이 안정화 되었을 때의 회전 움직임, 순목에 의한 이동거리, 중심위치를 비교하였다. 결과: 렌즈의 회전 움직임은 스팁하게 피팅하였을 경우 정상안 군은 얼라인먼트 피팅시와 큰 차이를 보이지 않았으나, 건성안 군에서는 눈물층이 안정화되는 시점에서의 평균 회전 움직임이 정상안 군보다 통계적으로 유의하게 컸다. 정상안 군에서는 피팅에 따른 렌즈 이동거리의 차이가 없었으나 건성안 군에서는 스팁하게 피팅된 경우 렌즈의 이동 거리가 증가하였다. 각막에서의 렌즈 중심 위치는 얼라인먼트 피팅된 렌즈를 착용한 정상안 군의 경우 수직 방향으로의 분포가 더 컸으나 건성안의 경우는 수평 방향으로의 분포가 더 컸다. 또한 건성안에 렌즈를 스팁하게 피팅하였을 때에는 렌즈를 착용한 직후 렌즈의 중심 위치가 수직방향으로도 다소 넓게 분포하였으며 눈물층이 안정화된 후에는 오히려 수평 방향의 분포가 좁아져 눈물층의 안정화에 따라 렌즈의 중심 위치가 변함을 알 수 있었다. 결론: 본 연구를 통하여 건성안에서의 소프트렌즈의 움직임과 중심 위치가 정상안의 경우와 상이하며 특히 스팁 피팅시에는 그 차이가 더 두드러짐을 알 수 있었다. 따라서 건성안에 소프트렌즈를 피팅할 시에는 본 연구를 통하여 확인할 수 있었던 정상안과의 차이를 고려해야 할 것으로 생각된다.

• 한국지반공학회:학술대회논문집
• /
• 한국지반공학회 2008년도 추계 학술발표회
• /
• pp.721-728
• /
• 2008

Top-Base Method is a stabilization method for light weight structures particularly in the soft ground. It is widely used for the increment of bearing capacity and the effect of restraining settlement when the bearing capacity of the ground is not enough. Top-shaped cone concrete foundations are installed in graveled laid over soft ground. The principle of the basic method is to maximize effect of dispersing the overburden pressure by increasing the contact area of the top-shaped cone. Therefore, the bearing capacity is increased and the settlement is decreased by the embedded resistance of pile part in the ground. In this paper, the plate bearing test was conducted to evaluate the feasibility of Top-Base foundation. Based on the test results, the coefficient of subgrade reaction, elastic modulus, and settlement of foundation on reclaimed land was derived.

• 한국항해항만학회:학술대회논문집
• /
• 한국항해항만학회 2021년도 추계학술대회
• /
• pp.17-18
• /
• 2021

컨테이너 터미널에서 운영 생산성 향상은 지속해서 요구되는 사항으로 첨단 ICT를 활용하는 관련 연구는 지속해서 이뤄지고 있다. 터미널 운영을 위한 핵심 정보시스템인 터미널운영시스템에서 AI, Big Data 등 관련 기술 활용에 따른 SW 프로그램 개발, 시험 및 안정화에 소요되는 노력을 줄일 목적으로 외부 전문가시스템 연계 방법에 대한 연구이다.

• Geomechanics and Engineering
• /
• 제36권4호
• /
• pp.329-341
• /
• 2024

Retaining structures are one of the most important elements in the stabilization of excavations and slopes in various engineering projects. Mechanically stabilized earth (MSE) walls are widely used as retaining structures due to their flexibility, easy and economical construction. These benefits are especially prominent for projects built on soft and weak foundation soils, which have relatively low resistance and high compressibility. For high retaining walls on weak foundations, conventional design methods are not cost-effective. Therefore, two alternative solutions for different foundation weakness are proposed in this research: optimized multi-tiered MSE walls and single tier wall with foundation improvement. The cost optimization considers both the construction components and the land price. The results show that the optimal solution depends on several factors, including the foundation strength and more importantly, the land price. For low land price, the optimized multi-tiered wall is more economical, while for high land price (urban areas), the foundation improvement is preferable. As the foundation strength decreases, the foundation improvement becomes inevitable.