• 대한치과보철학회지
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• 제40권5호
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• pp.507-524
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• 2002

Load transfer of implant overdenture varies depending on anchorage systems that are the design of the superstructure and substructure and the choice of attachment. Overload by using improper anchorage system not only will cause fracture of the framework or screw but also may cause failure of osseointegration. Choosing anchorage system in making prosthesis, therefore, can be considered to be one of the most important factors that affect long-term success of implant treatment. In this study, in order to determine the effect of anchorage systems on load transfer in mandibular implant overdenture in which 4 implants were placed in the interforaminal region, patterns of stress distribution in implant supporting bone in case of unilateral vertical loading on mandibular left first molar were compared each other according to various types of anchorage system using three-dimensional photoelastic stress analysis. The five photoelastic overdenture models utilizing Hader bar without cantilever using clips(type 1), cantilevered Hader bar using clips(type 2), cantilevered Hader bar with milled surface using clips(type 3), cantilevered milled-bar using swivel-latchs and frictional pins(type 4), and Hader bar using clip and ERA attachments(type 5), and one cantilevered fixed-detachable prosthesis(type 6) model as control were fabricated. The following conclusions were drawn within the limitations of this study, 1. In all experimental models. the highest stress was concentrated on the most distal implant supporting bone on loaded side. 2. Maximum fringe orders on ipsilateral distal implant supporting bone in a ascending order is as follows: type 5, type 1, type 4, type 2 and type 3, and type 6. 3. Regardless of anchorage systems. more or less stresses were generated on the residual ridge under distal extension base of all overdenture models. To summarize the above mentioned results, in case of the patients with unfavorable biomechanical conditions such as not sufficient number of supporting implants, short length of the implant and unfavorable antero-posterior spread. selecting resilient type attachment or minimizing distal cantilever bar is considered to be appropriate methods to prevent overloading on implants by reducing cantilever effect and gaining more support from the distal residual ridge.

• 한국항해항만학회지
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• 제39권3호
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• pp.233-239
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• 2015

최근 각종 해양사고 발생으로 인하여 해양 관련한 안전사고에 대한 문제들이 대두되고 있다. 이러한 사고 중 우리나라 연안에 위치한 31개소 무역항의 지정된 정박지 중 특히 외해개방형 정박지 경우 기상악화로 인하여 유효한 선박 파주력을 확보하지 못함으로서 주묘가 발생하여 사고 위험이 많아지고 있으나 정박선박의 안전성 확보나 정박지의 효율적인 운영을 위한 체계적인 정박지 안전관리 기준안은 미흡한 실정이다. 또한, 항만의 지리적인 위치 및 지형적인 특성으로 인하여 특정 조건의 외력에 취약한 외해 개방형 정박지 경우에는 태풍은 물론 강한 돌풍 등에 의해 선박은 주묘 가능성이 높아지고 이로 인한 2차 사고 발생이 우려된다. 본 논문에서는 외해개방형 정박지의 사례로 포항항의 경우 최근 주묘로 인한 해양사고 사례를 검토하여 입출항 선박의 크기별 한계외력을 계산하고 정박지 안전성을 확보할 수 있는 한계 외력을 선박 크기별 한계외력의 기준을 정하는 연구로 기존 개별 선박의 정박안전성 평가에 관한 연구들과 달리 정박선박의 안전성 확보 및 효율적인 정박지 운영을 위해 필요한 정박지 관리에 관한 기초적인 기준으로 활용할 수 있을 것으로 판단된다.

• Journal of the Korean Association of Oral and Maxillofacial Surgeons
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• 제29권4호
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• pp.245-248
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• 2003

The retraction of anterior teeth could be performed more easier by inducing of skeletal anchorage system rather than by conventional method on orthodontic treatment. But, we wonder how effective the system draws well without anchorage loss and draws anterior teeth aside posteriorly, and if the system can reduce the time, in comparison with the anchorage of posterior teeth. For that reason we have studied on the subject of patients, who were required the maximum anchorage on orthodontic treatment and the cases without crowding. The subjects of the experimental group are 35 areas of 20 people who were inserted miniscrews after Mx or Mn 1st premolar extracted. Also, the subjects of the control group are 81 areas of 45 people who were not inserted miniscrews. Compared the anchorage loss of experimental group with control one, we could get the result that the anchorage loss of experimental group is $1.034{\pm}0.891mm$ and control group is $2.790{\pm}1.882mm$(P<0.01). Compared the space closing time of experimental group with control one, we could get the result that the space closing time of experimental group is $369.40{\pm}110.81$days and control group is $406.56{\pm}231.63$days. But the result of comparing space closing time has no significance in statistics. We recognized that the experimental group is more faster than the control group in the canine retraction velocity from the result ; the speed of a experimental group has as much as $0.60{\pm}0.23mm/30days$ while the speed of a control group has $0.44{\pm}0.35mm/30days$(P<0.05). So, we could convince that orthodontic miniscrew is used effectively in the cases required the maximum anchorage.

• 한국구조물진단유지관리공학회 논문집
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• 제14권3호
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• pp.91-99
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• 2010

RC 구조물의 보강에는 여러 가지 보강공법이 사용되고 있으며 특히 외부강선 보강공법은 손상된 구조물을 보강하는 대표적인 공법이며 효율성, 용이성, 경제성의 면에서도 우수하다. 본 연구에서는 PSC 및 RC 거더에서 추가 손상 없이 충분한 보강효과를 얻을 수 있는 보강공법으로써 개선된 인양홀을 이용한 정착장치를 제안하였다. 2가지 유형의 새롭게 제안된 정착장치를 6개의 실험체의 적용하였고 기존의 정착장치를 3개의 실험체에 적용하였다. 한 개의 실험체는 보강효율을 판단하기 위하여 보강공법을 적용하지 않았다. 이들 정착장치의 거동을 분석하기 위하여 정적 재하 시험을 수행하였고 실험변수들은 정착장치의 형상, 강봉의 긴장정도와 강선의 설치형태이다. 각 실험체의 보강 효과를 조사하기 위해 처짐, 변형률 그리고 파괴양상을 기록하였으며 균열하중, 항복하중, 극한하중, 연성지수 그리고 강선의 응력을 분석하였다. 그 결과 제안된 인양홀을 이용한 정착장치는 기존의 정착장치보다 높은 보강효율을 보였으며, 에너지 개념을 이용한 연성도 평가에 따르면 충분한 연성을 확보하고 있음을 알 수 있었다.

• 해양환경안전학회지
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• 제20권6호
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• pp.663-670
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• 2014

평택항은 항만 물동량의 증가로 선박 입항척수가 꾸준히 증가하여 향후 대기 정박지의 부족이 예상되고 있다. 정박지와 같은 하나의 수역시설을 변경 및 확장 등 개선하고자 할 경우에는 부근 해역의 타 수역시설에 미치는 영향을 종합적으로 고려하여야 한다. 또한 해당 해역에 대한 향후 선박교통량을 정확하게 예측하여 변경하고자 하는 수역시설의 규모를 산정하여야 한다. 본 연구에서는 증가될 항만 물동량을 단위선박 당 처리량으로 계산하여 장래 평택항 선박 입항척수를 예측하였다. 예측한 결과 정박지의 정박 능력을 2030년에 초과하는 것으로 나타났다. 이는 현 각 정박지 동시 투묘가능척수인 12.6척과 1.6척을 상회하는 규모로 현 정박지의 확장 필요성이 제기되었다. 이에 각 정박지별 해상교통환경 분석으로 최적의 확장 방안을 검토하여, 입파도 정박지의 경우 정박예상 척수를 19.7척 그리고 장안서 정박지의 경우 정박예상 척수를 12.6척을 수용할 수 있는 규모의 개선안을 제시하였다.

• 한국구조물진단유지관리공학회 논문집
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• 제20권6호
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• pp.73-83
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• 2016

포스트텐션 공법을 적용한 콘크리트 부재의 정착구역에서 정착판 근처의 지압응력은 일반적으로 높은 프리스트레스 하중에 의해 발생한다. 따라서 단면의 효율적인 활용과 콘크리트 부재의 파괴로 이어질 수 있는 균열제어를 위해 적절한 정착판의 크기가 제시되어야 한다. 본 연구에서는 도로교설계기준 및 PTI 등에 의해 사각형 정착판과 원형 정착판의 유효면적에 대한 관계식을 제안하였다. 또한 정착판의 형상에 따라 형상계수를 제안하였으며, 유한요소해석을 통해 적절성을 분석하였다.

• Computers and Concrete
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• 제21권2호
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• pp.127-137
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• 2018

In this study, the behavior of the number of anchorage bolts on the glass-fiber reinforced polymer (GFRP) plates adhered to the surfaces of reinforcing concrete (RC) T-beams was investigated analytically. The analytical results were compared to the test results in term of shear strength, and midpoint displacement of the beam. The modelling of the beams was conducted in ABAQUS/CAE finite element software. The Concrete Damaged Plasticity (CDP) model was used for concrete material modeling, and Classical Metal Plasticity (CMP) model was used for reinforcement material modelling. Model-1 was the reference specimen with enough sufficient shear reinforcement, and Model-2 was the reference specimen having low shear reinforcement. Model-3, Model-4 and Model-5 were the specimens with lower shear reinforcement. These models consist of a single variable which was the number of anchorage bolts implemented to the GFRP plates. The anchorage bolts of 2, 3, and 4 were mutually mounted on each GFRP plates through the beam surfaces for Model-3, Model-4, and Model-5, respectively. It was found that Model-1, Model-3, Model-4 and Model-5 provided results approximately equal to the test results. The results show that the shear strength of the beams increased with increasing of anchorage numbers. While close results were obtained for Model-1, Model-3, Model-4 and Model-5, in Model-2, the rate of increase of displacement was higher than the increase of load rate. It was seen, finite element based ABAQUS program is inadequate in the modeling of the reinforced concrete specimens under shear force.

• 한국안전학회지
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• 제29권5호
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• pp.67-73
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• 2014

Construction equipment such as tower crane should be installed in a field without appropriate anchorage to cause a collapse of crane. The anchorage capacity can be varied with Anchor length, concrete strength, anchor diameter, hooked or non hooked these variables will be made and tested in the study. It is shown what anchorage capacity will be more effective case by case. Hooked and non-hooked rebar anchor concrete weight with dia 22mm rebar are shown with initial displacement at 170~220KN of hooked case and 200~210KN of non-hooked one which are linearly increased, without any ductility behavior with almost brittleness. Three(3) same test pieces are almost similarly behaviored without relation to hooked or non-hooked cases. It is found out that the bigger diameter of rebar becomes, the more resistant capacity could be made, but conversely ductility against sudden collapse similar to brittleness becomes the more insufficient. It is also found out that dia 16mm rebar could be more effectively applied to heavy support weight at construction sites.

• 수산해양교육연구
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• 제21권2호
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• pp.291-305
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• 2009

As you known well, Ulsan port is very famous for handling chemical products which occupies about 80% of quantities of all Korean ports. Many ship's operators prefer to handle liquid cargo es at proper anchorages instead of the berth for saving port expenses. Ulsan M-10 anchorage was assigned for handling liquid cargoes, however this anchorage's space is restricted by the oil pipeline which lays under seabed about 400m off from the center of M-10 anchorage, for which we have to consider of the external force and counter force for keeping the safety of anchoring. Where, external force is induced by wind, tidal currents and wave while counter force is induced by holding power of anchor/chain. In this study, author evaluated a method to analyze theoretically the limit of external force condition up to which an anchoring ship can keep her position without dragging, and for which applied to many kinds of combined Ships as mother ship of 50,000 DWT Tanker and 4 sizes of Tanker as alongsided ship.

• 한국공간구조학회논문집
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• 제20권1호
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• pp.41-48
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• 2020

In this study, the design of anchorage zone for unbonded post-tensioned concrete beam with single tendons of ultimate strength 2400MPa was evaluated to verify that the KDS 14 20 60(2016) and KHBDC 2010 codes are applicable. The experimental results showed that the bursting force equation of current design codes underestimated bursting stress measured by test, because the KDS 14 20 60(2016) and KHBDC 2010 propose the location of the maximum bursting force 0.5h which is the half of the height of member regardless of stress contribution. Although the allowable bearing force calculated by current design codes was not satisfied the prestressing force, the cracks and failure in anchorage zone was not observed due to the strengthening effect of anchorage zone reinforcement.