• 지질공학
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• 제17권2호
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• pp.299-307
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• 2007

한반도 남동부 지역 총 84개의 시추공에서 수행된 수압파쇄시험과 오버코어링시험 자료를 수집하여 현생 응력의 방향과 크기를 분석하였다. 한반도 남동부에 작용하는 평균 최대수평주응력 방향은 $N66^{\circ}{\pm}31^{\circ}E$로 나타났다. 주응력간의 상대적인 크기는 대부분의 지역에서 최대, 최소 수평주응력(${\sigma}_H,\;{\sigma}_h$)에 비해 연직응력(${\sigma}_v$)이 가장 작은 thrust fault stress regime을 보였다. 측압계수(K, 수평응력/연직응력) 연구지역의 북동부(삼척과 울진 포함)와 남서부(양산과 거제 포함)에서 상대적으로 높은 값(2.2

• 대한치과보철학회지
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• 제31권4호
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• pp.661-678
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• 1993

The purpose of this study was to analyze the stress distribution at supporting bone according to the types of endosseous implants. This investigation evaluated the stress patterns in rectangular photoelastic models produced by four different types of dental implants such as $Br\ddot{a}nemark$, screw type of Steri-Oss, blade type of Steri-Oss, IMZ with IMC and resin tooth using the techniques of quasi-three dimensional photoelasticity. All prostheses were casted in the same nonprecious alloy and were cemented or screwed on their respective implants and abutments. 20 kg of vertical load was applied on the central fossa of casted crown and 16 kg of inclined had was applied on the top third of distal surface of casted crown respectively. The results were as follows : 1. Under the vertical load, screw implants of Steri-Oss and $Br\ddot{a}nemark$ showed increasing stress condition between and around the screw threads along the implant lateral surface and cylindrical implant of IMZ showed the less stress condition along the lateral surface with concentration of stress mostly near the root apex. 2. Under the vertical load, the stress of Steri-Oss blade was distributed uniformly at the alveolar bone under the broad blade. 3. Under the inclined load, the stress concentration of Steri-Oss screw and $Br\ddot{a}nemark$ was developed highly around the mesiocervical bone area on the contralateral side to force application. The stress of $Br\ddot{a}nemark$ with flexible gold glod was more concentrated in the cervical bone area than that of Steri-Oss with stiff screw. 4. Under the inclined load, the stress of Steri-Oss blade broadly was distributed around the mesioceivical bone area and the lower and mesial bone area of the blade. 5. Under the Inclined load, IMZ implant showed the gap between c개wn and fixture due ta deformation of the IMC and IMZ was lower in stress concentration developed around the mesiocervical bone area than $Br\ddot{a}nemark$ and Steri-Oss screw. 6. Under the inclined load, the stress magnitude induced in the mesiocervical bone area of implants was in order of $Br\ddot{a}nemark$, Steri-Oss strew, IMZ and Stsri-Oss blade. 7. Tilting forces as compared to axial forces exerted greater magnitude of stress in the cervical bone area of the implant. 8. In respect of stress distribution, Steri-Oss blade was superior than any other implants and in respect of the stability by horizontal lone, IMB and $Br\ddot{a}nemark$ was inferior than any other implants.

• 구강회복응용과학지
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• 제21권1호
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• pp.1-14
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• 2005

The purpose of this study was to assess the loading distributing characteristics of implant prosthesis of internal connection system(ITI system) according to position and direction of load, under vertical and inclined loading using finite element analysis (FEA). The finite element model of a synOcta implant and a solid abutment with $8^{\circ}$ internal conical joint used by the ITI implant was constructed. The gold crown for mandibular first molar was made on solid abutment. Each three-dimensional finite element model was created with the physical properties of the implant and surrounding bone. This study simulated loads of 200N at the central fossa in a vertical direction (loading condition A), 200N at the outside point of the central fossa with resin filling into screw hole in a vertical direction (loading condition B), 200N at the centric cusp in a $15^{\circ}$ inward oblique direction (loading condition C), 200N at the in a $30^{\circ}$ inward oblique direction (loading condition D) or 200N at the centric cusp in a $30^{\circ}$ outward oblique direction (loading condition E) individually. Von Mises stresses were recorded and compared in the supporting bone, fixture, and abutment. The following results have been made based on this study: 1. Stresses were concentrated mainly at the ridge crest around implant under both vertical and oblique loading but stresses in the cancellous bone were low under both vertical and oblique loading. 2. Bending moments resulting from non-axial loading of dental implants caused stress concentrations on cortical bone. The magnitude of the stress was greater with the oblique loading than with the vertical loading. 3. An offset of the vertical occlusal force in the buccolingual direction relative to the implant axis gave rise to increased bending of the implant. So, the relative positions of the resultant line of force from occlusal contact and the center of rotation seems to be more important. 4. In this internal conical joint, vertical and oblique loads were resisted mainly by the implant-abutment joint at the screw level and by the implant collar. Conclusively, It seems to be more important that how long the distance is from center of rotation of the implant itself to the resultant line of force from occlusal contact (leverage). In a morse taper implant, vertical and oblique loads are resisted mainly by the implant-abutment joint at the screw level and by the implant collar. This type of implant-abutment connection can also distribute forces deeper within the implant and shield the retention screw from excessive loading. Lateral forces are transmitted directly to the walls of the implant and the implant abutment mating bevels, providing greater resistance to interface opening.

• Nuclear Engineering and Technology
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• 제54권1호
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• pp.357-373
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• 2022

The high-temperature gas-cooled reactor pebble-bed module project is the first commercial Generation-IV NPP(Nuclear Power Plant) in China. A new joint is used for the vertical support of RPV(Reactor Pressure Vessel). The steel corbel is integrally embedded into the reactor-cabin wall through eight asymmetrically arranged pre-stressed high-strength bolts, achieving the different path transmission of shear force and moment. The vertical monotonic loading test of two specimens is conducted. The results show that the failure mode of the joint is bolt fracture. There is no prominent yield stage in the whole loading process. The stress of bolts is linearly distributed along the height of corbel at initial loading. As the load increases, the height of neutral axis of bolts gradually decreases. The upper and lower edges of the wall opening contact the corbel plate to restrict the rotation of the corbel. During the loading, the pre-stress of some bolts decreases. The increase of the pre-stress strength ratio of bolts has no noticeable effect on the structure stiffness, but it reduces the ultimate bearing capacity of the joint. A simplified calculation model for the elastic stage of the joint is established, and the estimation results are in good agreement with the experimental results.

• 대한치과보철학회지
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• 제44권5호
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• pp.584-593
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• 2006

Statement of problem : Dental implant which has been developed gradually through many experiments and clinical applications is presently used to various dental prosthetic treatments. To conduct a successful function of implant prosthesis in oral cavity for a long time, it is important that not only structure materials must have the biocompatibility, but also the prosthesis must be designed for the stress, which is occurred in occlusion, to scatter adequately of load support. Therefore, it is essential to give the consideration about the stress analysis of supporting tissues for higher successful rates. Purpose : Recently, many implant manufacturing company produce various taper design of root form implant, the fixture is often selected. However, the stress analysis of taper form fixture still requires more studies. Material and method : This study we make the element models that five implant fixture; Branemark system(Nobel Biocare, Gothenberg, Sweden), Camlog system(Altatec, Germany), Astra system(Astra Tech, Sweden), 3i system(Implant Innovations Inc, USA), Avana system(Osstem, Korea) were placed in the area of mandibular first premolar and prosthesis fabricated, which we compared with stress distribution using the three-dimension finite element analysis under two loading condition. Results : This study compares the aspect of stress distribution of each system with the standard of Von mises stress, among many resulted from finite element analysis so that this research gets the following results. 1. In all implant system, oblique loading of maximum Von mises stress of implant, alveolar bone and crown is higher than vertical loading of those. 2. Regardless of loading conditions and type of system, cortical bone which contacts with implant fixture top area has high stress, and cancellous bone has a little stress. under the vertical loading, maximum Von mises stress is more higher in order of Branemark, Camlog, Astra, 3i, Avana. under the horizontal loading, maximum Von mises is more higher in order of Camlog, Branemark, Astra, 3i, Avana.

• 콘크리트학회논문집
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• 제13권2호
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• pp.93-98
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• 2001

CFT 기둥은 탁월한 구조적 성능을 발휘하는데, 이는 강관과 콘크리트의 복합거동에 기인하는 것이다. 이러한 CFT 기둥의 거동을 예측하기 위해서는 강관과 콘크리트 사이의 부착거동을 파악해야 한다. 그러나 이형철근을 대상으로 한 대부분의 기존 모델식은 CFT 기둥에 적용할 수 없으므로, 새로운 모델식의 개발이 필요하다. 본 논문의 목적은 구속압이 발현된 상태의 CFT 기둥에서 콘크리트와 강관의 부착응력과 수직응력의 관계, 기둥단면에서의 응력 분포도를 고려한 부착거동에 관한 모델식의 개발이다. 평형조건으로부터 콘크리트와 강관의 부착응력과 수직응력의 관계를 유도하였으며, 이차원 문제의 Airy 응력함수(stress function)로부터 CFT 기둥 단면에서의 횡방향 응렬 관계를 파악하였다. 그리고 5개의 CFT 기둥 실험체에 대해 콘크리트에만 하중을 가하는 실험을 실시하였고, 측정된 변형률로부터 회귀분석의 방법을 통해 부착강도와 횡방향 구속압의 관계를 파악하였다. 이로부터 새로운 부착강도 모델식을 제안하였으며, CFT 기둥에서 콘크리트만 가압한 경우의 각 방향 응력관계를 파악하였다.

• 한국철도학회:학술대회논문집
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• 한국철도학회 2007년도 춘계학술대회 논문집
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• pp.395-403
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• 2007

Railroad track consists of relatively simple structures such as rail, sleeper, ballast. Roadbed shares vertical pressure by train load which passed through rail to ballast as base that supports the track. For evaluating stress and displacement of roadbed due to the railroad load is an important role on the track as a basic data for estimation of the durability and design of the roadbed thickness. GEOTRACK program applied multi-layered theory was developed for analyzing railroad track structure. GEOTRACK program is a sort of numerical analysis program which has advantage that can analysis component of track by simple method. In this study, this program was used to preform the numerical analysis by changing track conditions and roadbed conditions such as tie, reinforced roadbed, dynamic wheel load, Resilient modulus and so on. Further detail will be presented on the paper.

• 한국안전학회지
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• 제15권1호
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• pp.132-139
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• 2000

In this study, the fatigue life assessments of steel railway bridge in Japan National Railway were carried out. This railway bridge has been under in service from 1957, and fatigue damages were occurred at bead toe of upper part of vertical stiffeners of stringers, bead toes of scallop in lower part of vertical stiffeners in stringers and crossings of cross beams and stringers. From this study, a series of field tests were carried out by stress history measurement about above mentioned points. And as a results of stress histogram analysis, cummulative fatigue damage rate and fatigue life of these members should be calculate quantitatively. And from this estimation technique, cummulative fatigue damage rate and fatigue life of this railway bridge were strongly affected in passing tonage every year and the histories of live load.

• 한국공간구조학회논문집
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• 제3권1호
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• pp.57-68
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• 2003

This paper have performed to investigate the influence of certain parameters, including the boundary condition types, load ratios of the steel beams, and span/depth ratios of the beams itself on the structural behaviour of the steel beams at elevated temperatures. This paper is analysed the stress and vertical deflection at mid-span of the steel beams at elevated temperatures and also predicted 'failure' temperatures of the steel beams at elevated temperatures. Fire analysis used here is analysed by software VULCAN. Design examples are given to describe the structural behaviour of the steel beams at elevated temperatures.

• 한국지반공학회:학술대회논문집
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• 한국지반공학회 1999년도 연약지반처리위원회 학술세미나
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• pp.62-70
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• 1999

Artesian pressure exists in Yangsan site, the maximum value of which has been measured as high as 5 t/m$^2$. This paper deals with the prediction of consolidation settlement for the site with artesian pressure. The consolidation settlement at the site has been accelerated using vertical band drains. Since the artesian pressure gives lower effective stress than a static condition, its effect should be considered in the settlement prediction. This case study shows that the prediction of settlement and pore pressure dissipation agrees well with the measurements, when considering the artesian effect.